Climate Change Myths and Realities

Climate Change Myths & Realities

? Dr. S. Jeevananda Reddy

Climate Change: Myths & Realities

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Dr. S Jeevananda Reddy


Dr. S. Jeevananda Reddy

Hyderabad 4th November, 2008


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Table of Contents Preface Chapter 1: Earth’s Atmosphere Chapter 2: Ozone Depletion Chapter 3: Solar Radiation Chapter 4: Weather & Climate Chapter 5: Climate Change Chapter 6: Systematic Variations Chapter 7: Ecological Change Chapter 8: Global Warming Chapter 9: Extreme Weather & Climate Events Summary References

Annexure I.

Major Air Pollutants

List of Tables 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Sky colours vs wavelengths Most polluted cities by PM in 2004 Regression parameters vs Calendar months Variation of “a” and “b” with seasons Monthly Cyclonic disturbances in Arabian Sea & Bay of Bengal during 1891-1990 Estimated amplitudes and phase angles of four cycles in Fortaleza rainfall data series Estimated amplitudes and phase angles of Durban & Catuane rainfall data series Estimated number of Vehicles vs Population Temporal variation of the irrigated area in the three sub-divisions of AP Number of years under different groups of Typhoon days vs all- India Summer Monsoon Rainfall during 1959-1991 [26-years] Average rainfall amounts & C.V.s in the three meteorological sub-divisions of AP during 1871-1994 Extreme events of rainfall & dates of onset in AP during 1871-1994 Percent average rainfall in the three sub-divisions of AP during 1987-1990 Monthly and daily highest rainfall of Cochin


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List of Figures 1a. Atmosphere layers 1b. Atmospheric layers vs Temperature pattern 1c. Latitudinal distribution of Tropopause level 2a. 2b. 2c. 2d. 2e. 2f. 2g. 2h.

Solar Radiation Spectrum Sources of stratospheric chlorine Time series of the lowest values in ozone hole as measured by TOMS Image of the largest Antarctic ozone hole (September 2006) Annual march of Antarctic total ozone in Summer & Spring Annual March of Arctic total ozone in Summer & Winter Seasonal variation of Antarctic ozone Annual march of total ozone variations with latitudes

3a. Variation of Solar radiation with latitude & seasons on the top of the atmosphere 3b. Generalized Earth’s radiation budget 3c. Variation ϕij with Calendar months (j = January to December in Northern Hemisphere, respectively refer to July to June of Southern Hemisphere & i = 1 to 3 respectively for inland, coastal & hill stations] 3d. Rt distribution over India for four representative months 3e. Rn distribution over India for four representative months 3f. Rt distribution over northeast Brazil for the twelve months 4a. 4b. 4c. 4d. 4e. 4f. 4g. 4h.

Climates of the World — Koppen’s classification Primary storm tracks Climates of India — Koppen’s classification Monsoon onset pattern in India Rainfall regimes in India Temperature regimes in India Drought Prone areas in India Planting hazard zones in India

5a. Average annual change in climate in response to doubled carbon dioxide (expected by 2030 to 2050) 5b. Sensitivity of land suitable for cereal production to climate change 6a. 400 Years of Sunspot Observations 6b. Smoothed mean excess Annual Rainfall in the three Northern Hemisphere Zones compared with the corresponding Normalized Annual Sunspot Numbers


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6c. Difference between the actual and normal annual rainfalls at two Latitudes in Australia in Southern Hemisphere 6d. Smoothed Annual Rainfall Totals at Fortaleza in Southern Hemisphere and Annual Sunspot Numbers 6e. Smoothed Annual Rainfall Totals at three places in South Africa in Southern Hemisphere and Annual Sunspot Numbers 6f. Ten-Year smoothed means of the Annual Rainfall quartile for Adelaide in Australia and Normalized Sunspot Numbers 6g. Smoothed means of the July central-England temperatures compared with the conventional double Sunspot Cycle 6h. Five-year means of the Annual lighting incidence Index compared with Sunspot Numbers 6i. Smoothed variations in Magnetic Intensity at Eskdalemuir and Stonyhurst in Great Britain with central-England winter Temperatures and Annual Rainfall for England and Wales 6j. Magnetic Intensity and information about the Temperature obtained from a single deep-sea core 6k. Reconstructed Past Temperature Time Series 6l. Standardized time series of rainfall anomalies for the twentieth century (top) and a century period of the GFDL model simulation containing the most prominent dry episodes (bottom) 6m. Annual march of dates of onset of Southwest Monsoon over Kerala Coast in India along with 10-year moving average 6n. Observed and predicted seasonal trend in annual rainfall data of Fortaleza in Brazil 6o. Observed and predicted seasonal trend in annual rainfall data of Mahalapye in Botswana, Southern Africa 6p. Annual march of observed & predicted annual rainfall of Catuane in Mozambique, southern Africa 6q. Seasonal pattern of annual rainfall at few selected locations in Ethiopia, northern Africa: (a) Gore, (b) Jijiga, (c) Asmara, and (d) Mayole 6r. Observed and predicted seasonal trend in annual rainfall of Durban/Louis Botha in South Africa 6s. Annual march of observed and predicted Southwest Monsoon season rainfall of India 6t. Annual march of observed and predicted Southwest & Northeast Monsoon rainfall of three meteorological sub-divisions of Andhra Pradesh in India 7a. Urban land use change for Chicago-Milwaukee during 1955-1995 7b. Urban change in the Williamette Valley region over 115 years (1880-1995)


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7c. Urban growth in and around Washington, D.C. over 200 years (1880 – 1990) with a projection for 2025 7d. Changes in urban, agriculture, and forested lands in the Patuxent River Watershed over 140 years (1850 – 1992) 7e. A City makes its own Weather – Vertical section 7f. Summer, in the city – downtown Sacramento 7g. Hot time in Sacramento in 1998 7h. Islands of urban warmth – urban to rural section 7i. Rate of heat island growth in 11 cities in USA 7j. Impact of orography changes on Rainfall of Santacruz in Mumbai 7k. Impact of cool-island on rainfall in the three meteorological Sub-divisions of AP during SWM & NEM 8a. 8b. 8c. 8d. 8e. 8f. 8g.

Projections of Global Warming under different model forms Atmospheric Carbon Dioxide increase in the past 200 years Monthly mean carbon dioxide concentrations Total global level fossil fuel consumption Number of stations measuring GHGs elements Global & Hemispherical Average Temperature Patterns during 1850-2006 Global Average Temperature series as measured by Satellites & upper air Balloons

9a. Hydrological Cycle 9b. Five-year Running mean of Atlantic Basin Hurricanes during 1851- 2006 9c. Cyclones per year during 1945-2000 (May to November) in Bay of Bengal Region as presented by Joint Typhoon Warning Centre 9d. Global Five-year and Annual Average Temperature Patterns


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Preface The “Science of Climate Change” has turned into a political satire of “Global Warming & Carbon Credits”. In tune with this the “Science of Climate Change” moved from a scientific body, the World Meteorological Organization (WMO), into an elected political body, the Intergovernmental Panel on Climate Change (IPCC) and as a result the scientific community and the media along with political communities started thinking locally and acting globally. In this process the major casualty is the health of life forms on the Earth, more particularly in developing countries, most of which are located in “warm” tropics. The literature is flooded with statements such as: Eleven of the world’s most respected national science academies, including the U.S. National Academy of Sciences, issued a joint statement in anticipation of the 2005 G8 Summit: “Climate Change is real. There will always be uncertainty in understanding a system as complex as the world’s climate. However, there is now strong evidence that significant Global Warming is occurring”. The statement called on world leaders to acknowledge, “The threat of Climate Change is clear and increasing”, and urged all nations “to take prompt action to reduce the causes of Climate Change”. The new study Commissioned by the UN Office for the Coordination of Humanitarian Affairs and the non-governmental organization CARE International identified India, Pakistan, Afghanistan and Indonesia as being among Global Warming “hotspots” or countries particularly vulnerable to increases in extreme drought, flooding and cyclones anticipated in coming 20 to 30 years. (Humanitarian Implications of Climate Change, August 2008). Al Gore has been actively campaigning to stir action at various levels to combat the impending climate crisis. An Inconvenient Truth, a movie on climate change produced by him presents what he thought, “the scientific evidence on the human driven climate change”, which fetched him the Noble Prize with huge world-wide Public Relation (PR) campaign, that includes a large contingent from India too. The unscientific nature of all these statements is seen from IPCC observation, the fact that “These basic conclusions have been endorsed by at least thirty Scientific Societies and Academies of Science. While the individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with IPCC on the main conclusion”. In this, the basic question to be answered from such pronouncements is: “Should the science be based on what many accepted/endorsed or should it be based on what is scientifically valid? Or should it be based on PR campaign” and yet IPCC received the Noble Prize. This has become the deathbed to the “Science of Climate Change”. The fact is that both the ozone “creation & destruction” and “cooling & warming” of global temperatures are in built in nature. There is an absolute one-toone relation in ozone depletion theory and thus, though in the initial stages there was a stiff opposition from industry, it became easy to replace ozone depleting


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substances by non-ozone depleting substances. The reversing trend in ozone depletion is already evident. Unfortunately, there is no such one-to-one relation in global warming theory, as there are several process involved. The issue is not moving in the right direction, as political interests are inter-woven in the issue of global warming, that is leading no where. Therefore, there is an urgent need to take a re-look into the “Science of Climate Change” and scientists at individual level and organization level must go back to the studies made in the field of climate change prior to 1980s. It is more important in the developing countries wherein a majority of people depends on agriculture in which climate is the backbone of agriculture. The present book looks in this angle of climate change perspective. Though this may need both physical & mental action unlike in the modeling activity, it is a worthwhile exercise. It is not the objective of the book to say “control of greenhouse gases is not an important issue in relation to global temperature rise which has political ramifications” but on the contrary it’s objective is to “highlight the importance of controlling the greenhouse gases/pollution in relation to their direct impacts on the life forms which have human ramifications at local level” – think globally but act locally. Therefore, the main objective of this book is to bring to the notice of rulers of the day, the importance of systematic changes in climate that are beyond human control & other changes in climate due to human interference that have significant effect on agriculture and life forms on the Earth. One of the main components of human interference is ecological change such as land use/land cover changes. Ecological changes not only influence the radiation balance but also the greenhouse gases balance in the atmosphere. These will automatically contribute to global control processes, either directly or indirectly. It is difficult to change the western-mind set of people, unless they come out from that web and try to understand the others point of view that really benefit the developing nations like India. Hypocrisy thy name!!! They are more interested in public relation propaganda to fetch awards-rewards to western vested masters, who are the agents of multinational companies. These PR propaganda groups talk against thermal power industry & Hydroelectricity through big dams but failed to talk of industries that are involved in green revolution technology; & biotechnology, which are in the hands of multinational companies, or industries that manufacture the drugs to treat the new diseases created by the green revolution technology, which in turn create more new diseases; as well the biotechnology that causes the destruction of plant species in developing countries. The author used some of the text & figures from Internet & other sources of several scientists. I herewith acknowledge all those scientists with great respect.

Hyderabad 4th November 2008

Dr. S. Jeevananda Reddy


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Chapter 1

Earth’s Atmosphere 1.1

Natural Composition of Atmosphere

The Earth’s Atmosphere is a layer of gases and retained by gravity. It contains around 78.0842% of nitrogen, 20.9463% of oxygen, 0.9342% of organ, 0.0381% of carbon dioxide, 0.002% of other gases and around 1 to 4% of water vapour. This mixture of gases is commonly known as air. This regulates the Sun’s energy reaching the Earth’s surface. There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere’s mass is within around 11 km from the Earth’s surface. However, the composition of the atmosphere varies, depending up on the location, the weather, and many other factors. There may be more water in the air after a rainstorm, or near the Ocean. Volcanoes can put large amounts of dust particles high into the atmosphere. Pollution can add different gases or dust and soot. 1.2

Atmospheric Layers

The temperature presents a peculiar behaviour as we go up from the Earth’s surface into space. Based on the system of variations in temperature with altitude, the Earth’s Atmosphere is divided into five layers [Figure 1a]. It is thickest near the surface and thins out with the height until it eventually merges with the space. 1.2.1 Troposphere Troposphere is the lowest layer of the atmosphere. It begins at the Earth’s surface and extends to around 17 km at the poles and 21 km at the equator — if one goes through the internet literature, different articles & figures present different heights —, with some variations due to weather factors. The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses, which makes them less dense so they rise. When an air mass raises, the pressure upon it decreases so it expands, doing work against the opposing pressure of the surrounding air. To do work is to expend energy, so the temperature of the air mass decreases (Figure 1b]. As the temperature decreases, water vapor in the air mass may condense or solidify, releasing latent heat that further uplifts the air mass. This process determines the maximum rate of decline of temperature with height, called the adiabatic lapse rate. Troposphere contains roughly 80% of the total mass of the atmosphere. Weather occurs only in this layer because it is this layer that contains most of the water vapour. Weather is the way water changes in the air, and so without water there would be no clouds, rain, snow or other weather features. The troposphere is an unstable layer where the air is constantly moving. As a result, aircraft flying through the troposphere may have a very bumpy ride – what we know as turbulence. Because of this turbulence, most jet airlines fly above troposphere, where the air is more still and clear as they can fly above the Clouds.


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Tropopause: It is a boundary in the atmosphere between the troposphere and the next layer, known as stratosphere [Figure 1c]. Here the air ceases to cool at around –50 °C (-58 °F), and the air becomes almost completely dry. It is at its highest level over the equator and the lowest over the geographical North Pole and South Pole. On account of this, the coolest layer in the atmosphere lies at about 21 km over the equator and around 17 km at poles. Due to the variation in starting height, the tropopause extremes are referred to as the equatorial tropopause and the polar tropopause. Measuring the lapse rate through the troposphere and the stratosphere identifies the location of the tropopause. In the troposphere, the lapse rate is, on an average 6.5 °C per km. That is to say, for every km in height, the temperature decreases by 6.5 °C. The region of the atmosphere where the lapse rate changes from positive (in the troposphere) to negative (in the stratosphere), i.e., where the temperature no longer decreases with altitude but rather increases, is defined as the tropopause. This occurs at the equilibrium level, a value important in atmospheric thermodynamics. The literature presents several ways of defining tropopause. They are for example: •

The definition used by the World Meteorological Organization (WMO) is: the lowest level at which the lapse rate decreases to 2 °C/km or less, provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 °C/km.

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A dynamic definition of the tropopause is used with potential vorticity instead of vertical temperature gradient as the defining variable. There is no universally used threshold: the most common ones are: the tropopause lies at the 2 PVU or 1.5 PVU surface. PVU stands for potential vorticity unit. This threshold will be taken as a positive or negative value (e.g. 2 and -2 PVU), giving surfaces located in the Northern and Southern Hemisphere respectively. To define a global tropopause in this way, the two surfaces arising from the positive and negative thresholds need to be joined near the equator using another type of surface such as a constant potential temperature surface.

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It is also possible to define the tropopause in terms of chemical composition. For example, the lower stratosphere has much higher ozone concentrations than the upper troposphere, but much lower water vapour concentrations; so appropriate cutoffs can be used.

The tropopause is not a “hard” boundary. Vigorous thunderstorms, for example, particularly those of tropical origin, will overshoot into the lower stratosphere and undergo a brief (hour-order) low-frequency vertical oscillation. Such oscillation sets up a low-frequency atmospheric gravity wave capable of affecting both the Atmospheric and the Oceanic currents in the region. Most commercial aircraft are flown in the tropopause.


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Thermal Inversions: In meteorology, in the normal situation, the temperature decreases as you go up in altitude in the troposphere. An inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to a temperature inversion, known as thermal inversion, i.e., an increase in temperature with height, or to the layer within which such an increase occurs. There are several reasons why an inversion might develop. One situation in which a low level, or surface inversion, might take place is on a clear night, when the earth’s surface radiates heat away rapidly. If the air is clear, the ground, and the air directly above it, can be cooler than the air at higher altitudes. This type of situation may occur on winter nights in California, and can be a problem for citrus growers, because if enough heat radiates away, the temperature at the ground surface can drop below the freezing level. Another type of inversion, called an advectional inversion, involves a horizontal inflow of cold air. This might be air blowing in from cold water to a coastal area. Along the California coast, winds frequently blow onshore, passing over the cold ocean waters before reaching land. When this occurs, the air at ground level may be colder than the air above it, and the air is stable. A third type of surface inversion takes place at night in valleys, when cold, dense air flows down slope under the influence of gravity, draining off the slopes and uplands, and into the valleys. The air in the valley bottoms is colder than the air above. Other types of inversions may also develop under various conditions. In California, upper air inversions develop because much of California is on the eastern edge of the subtropical high-pressure cell in the Pacific Ocean. This high-pressure cell develops in response to global patterns of atmospheric pressure and circulation, rather than local conditions. The presence of high pressure means that the air in the region is subsiding from high altitudes in the atmosphere. The increasing pressure of the surrounding air compresses the subsiding air as it descends, so the air warms up as it subsides. So not only is there cool air at ground level (from onshore flow of cool air), there is also a general subsidence of warm air aloft. The inversion layer acts as a lid to prevent air at ground level from rising and dispersing. If there are mountains inland, the mountains can also help trap the air. This means that any pollutants emitted accumulate in the trapped air. The bottom line is that conditions in California frequently favor the development of temperature inversions. The pollutants will continue to become more concentrated until a change in the weather leads to the breakup of the inversion layer. The normal decrease in temperature with altitude has lots of implications for weather. In the context of air pollution, it means that the decrease in temperature helps to mix the air, and disperse pollutants. If a parcel of air is warmer than the surrounding air, it is less dense, more buoyant, and it has a tendency to rise up until it finds air that is about the same temperature and density as it is. This helps disperse pollutants at the surface. On the other hand, air, which is cold and dense, is likely to be stable, and stay put. A very stable situation would occur when cold air is near the ground, and there is a layer of warmer air above it. This cold air is denser than the warm air above it. It resists rising, and is described as stable


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air. Above the inversion layer, the air will again cool off with increasing altitude. In urban areas, in winter, the inversions occur more frequently than in its’ neighbouring rural areas. Here heat is released by vehicles and buildings. An inversion can lead to pollution such as smog being trapped close to the ground, with possible adverse effects on health. An inversion can also suppress convection by acting as a “cap”. If this cap is broken for any of several reasons, convection of any moisture present can then erupt into violent thunderstorm. Photochemical smog is brown smog, the gray-brown haze that fills the air in many cities. It is especially a problem in warm, sunny regions where there are lots of cars burning gasoline. Researchers in the 1940’s and 1950’s in Los Angeles noticed that the kinds of pollutants in the air varied over the course of the day. Some pollutants increased in the morning, as people started driving their cars. Other pollutants, including the visible, brown smoggy haze, were most common in the middle of the day. The mix of pollutants changed again in the late afternoon and evening. It became apparent that the chemical reactions among the various pollutants were related to sunlight. Smog is worse in Los Angeles—and everywhere— in the summer, because the light energy from the Sun moves some of the reactions along. To form photochemical smog, three main ingredients are needed: nitrogen oxides (NOx), hydrocarbons, and energy from the Sun in the form of ultraviolet light (UV). The first thing that starts the chain of events is that people start driving in the morning. As gasoline is burned, nitrogen (N2) in the atmosphere is also burned, or oxidized, forming nitric oxide (NO): N2 + O2 = 2NO. Hydrocarbons and carbon monoxide (CO) will also be emitted by cars. Hydrocarbons are volatile organic compounds that may include acetaldehyde, formaldehyde, ethylene, and many other compounds. In the air, nitric oxide combines with molecular oxygen to form nitrogen dioxide within a few hours as: 2NO + O2 --->2NO 2. Nitrogen dioxide absorbs light energy and splits to form nitric oxide and atomic oxygen: NO2--->NO + O. Then, in sunlight, the atomic oxygen combines with oxygen gas to form ozone (O3): O+ O2--->O3. If no other factors are involved, ozone and nitric oxide then react to form nitrogen dioxide and oxygen gas as: O3 + NO<------>NO2 + O2. This last reaction can go in either direction, depending on temperature and the amount of sunlight. If there is a lot of sunlight, the equation moves to the left, and more ozone is produced. If nothing else gets in the way, equilibrium is reached, and the ozone level stabilizes. However, there is something else involved. Remember that the cars are also emitting hydrocarbons as well as oxides of nitrogen. Hydrocarbons are the other main ingredient in photochemical smog. When hydrocarbons are present, nitric oxide reacts with them instead of the ozone. This reaction produces a variety of toxic products, such as a volatile compound known as PAN (peroxyacetyl nitrate): NO + hydrocarbons ----->PAN and various other compounds.

Also,

NO2 +hydrocarbons ----->PAN and various other compounds So, there are two results (at least) from the reaction of nitrogen oxides with hydrocarbons. One is that a lot of volatile, reactive organic compounds are generated


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directly. The other is that when the nitric oxide (NO) is busy reacting with hydrocarbons, it is not reacting with ozone to break it back down to molecular oxygen. So the amount of ozone in the air increases. With nitric oxide reacting with hydrocarbons, ozone may accumulate to damaging levels. (Ozone may also be released into the air naturally by forest fires. But in a natural situation, ozone would react with nitric oxide and be broken down to oxygen, as noted above). The result, then, is an accumulation of ozone and volatile organic compounds such as PAN. These are referred to as secondary pollutants, because they are formed by the reaction of primary pollutants, nitrogen oxides and hydrocarbons, emitted by burning fossil fuels. The energy from the sun moves the reactions along. This forms photochemical smog, the brown gunk we see in the sky, especially on hot sunny days. Photochemical smog can cause eye irritation and poor visibility. Strong oxidants such as ozone can damage the lungs. The oxidants irritate the linings of lungs. Damage to the lungs may stress the heart. Health damage is worse for people with existing lung and heart conditions. Other health implications may include loss of immune system function, increased susceptibility to infections, and fatigue. The damage can be caused by exposure to large amounts of the pollutant over a short time span, and also by chronic exposure to small amounts over long periods of time. Oxidants can kill plant cells, causing leaves to develop brown spots or drop off the plant, reduce plant growth, and make plants more susceptible to damage from other causes. Oxidants such as ozone can also corrode and destroy many materials such as rubber, nylon, fabric, and paint. This is a simplified discussion of photochemical smog formation. There are more reactions involved, and a number of loops and sub-loops in the sequence of reactions. 1.2.2 Stratosphere The stratosphere is the second layer of air above the Earth’s surface and extends to a height of 50 km from the tropopause (Figure 1c). The temperature increases with the height (Figure 1b). The stratosphere contains the ozone layer, which contains relatively high concentrations of ozone. It is mainly located in the lower stratosphere, though the thickness varies seasonally and latitudinally. The ozone layer absorbs much of the Sun’s harmful radiation that would otherwise be dangerous to plant and animal life. It is a stable layer and because of this jet aircrafts generally fly in the stratosphere. 1.2.3 Mesosphere Beyond the stratosphere the air is very thin and cold. This area is known as the mesosphere, and is found between 50 km and 80-85 km above the Earth’s surface, wherein the temperature decreases with the height (Figure 1b). This is the layer in which meteors burn up when entering the atmosphere. 1.2.4 Thermosphere The thermosphere is the last layer in the atmosphere. It is located above 8085 km wherein the temperature increases with height (Figure 1b). Space shuttles fly in this area and it is also where the aurora lights are found. Auroras are wispy


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curtains of light caused when the Sun strikes gases in the atmosphere above the Poles. Thermosphere consists of Ionosphere and exosphere [Figure 1a]. Ionosphere is a part of the atmosphere that is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. Exosphere is the upper limit of our atmosphere. It starts from a height of about 500 km and extends around 1000 km. The atmosphere merges into space in the extremely thin exosphere. Satellites are stationed in this area. 1.3

Atmospheric pressure

Atmospheric pressure is a direct result of the total weight of the air above the point at which the pressure is measured. This means that air pressure varies with the location and the time, because the amount (and weight) of air above the Earth varies with the location and the time. The average atmospheric pressure at sea level is about 1013.2 mb and the total atmospheric mass is 5.1361 x 1018 kg. Atmospheric pressure decreases with height, dropping by 50% at around an altitude of about 5.6 km (18,000 ft). Equivalently, about 50% of the total atmospheric mass is within the lowest 5.6 km. This pressure drop is approximately exponential, so that pressure decreases by approximately half every 5.6 km. The temperature changes throughout the atmospheric column as well as the force of gravity begin to decrease at great altitudes. 50% of the atmosphere by mass is below around an altitude of 5.6 km; 90% of the atmosphere by mass is below around an altitude of 16 km; 99.99997% of the atmosphere by mass is below around 100 km. Therefore, most of the atmosphere (99.9997%) is below 100 km, although in the rarefied region above this there are auroras and other atmospheric effects. 1.4

The Sky Looks Blue!!!

Visible light is the part of the electromagnetic spectrum that our eyes can see. Light from the Sun or a light bulb may look white, but it is actually a combination of many colors. We can see the different colors of the spectrum by splitting the light with a prism. The spectrum is also visible when you see a rainbow in the sky. The colors blend continuously into one another. At one end of the spectrum are the reds and oranges. These gradually shade into yellow, green, blue, indigo and violet. The colors have different wavelengths, frequencies, and energies.


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Table 1: Sky Colours vs wavelengths Colour Interval

Wavelength wavelength (mm)

Typical (mm)

Violet

0.390-0.455

0.430

Dark blue

0.455-0.485

0.470

Light blue

0.485-0.505

0.495

Green

0.505-0.550

0.530

Yellow-green

0.550-0.575

0.560

Yellow

0.575-0.585

0.580

Orange

0.585-0.620

0.600

Red

0.620-0.760

0.640

Violet has the shortest wavelength in the visible spectrum. That means it has the highest frequency and energy. Red has the longest wavelength, and lowest frequency and energy. Light travels through space in a straight line as long as nothing disturbs it. As light moves through the atmosphere, it continues to go straight until it bumps into a bit of dust or a gas molecule. Then what happens to the light depends on its wavelength and the size of the thing it hits. Dust particles and water droplets are much larger than the wavelength of visible light. When light hits these large particles, it gets reflected, or bounced off, in different directions. The different colors of light are all reflected by the particle in the same way. The reflected light appears white because it still contains all of the same colors. Gas molecules are smaller than the wavelength of visible light. If light bumps into them, it acts differently. When light hits a gas molecule, some of it may get absorbed. After awhile, the molecule radiates (releases, or gives off) the light in a different direction. The color that is radiated is the same color that was absorbed. The different colors of light are affected differently. All of the colors can be absorbed. But the higher frequencies (blues) are absorbed more often than the lower frequencies (reds). This process is called Raleigh scattering — It is named after Lord John Raleigh, an English physicist, who first described it in the 1870’s. The blue color of the sky is due to Raleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. The air affects little of the red, orange and yellow light. However, the gas molecules absorb much of the shorter wavelength light. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue. As you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white. On the Earth, the Sun appears yellow. If you were out in space, or on the


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Moon, the Sun would look white. In space, there is no atmosphere to scatter the Sun’s light. On the Earth, some of the shorter wavelength light (the blues and violets) is removed from the direct rays of the Sun by scattering. The remaining colors together appear yellow. Also, out in space, the sky looks dark and black, instead of blue. This is because there is no atmosphere. There is no scattered light to reach your eyes. As the Sun begins to set, the light must travel farther through the atmosphere before it gets to you. More of the light is reflected and scattered. As less reaches you directly, the Sun appears less bright. The color of the Sun itself appears to change, first to orange and then to red. This is because even more of the short wavelength blues and greens are now scattered. Only the longer wavelengths are left in the direct beam that reaches your eyes. The sky around the setting the Sun may take on many colors. The most spectacular shows occur when the air contains many small particles of dust or water. These particles reflect light in all directions. Then, as some of the light heads towards you, different amounts of the shorter wavelength colors are scattered out. You see the longer wavelengths, and the sky appears red, pink or orange. 1.5

Effect of Human Interference!!!

1.5.1 Air Pollution Atmospheric pollution, also commonly called air pollution, is derived chiefly from the spewing of gasses and solid particulates into the atmosphere. Many pollutants such as dust, pollen, and soil particles occur naturally, but most air pollution, as the term is most commonly used and understood, is caused by human activity. Although there are countless sources of air pollution, the most common are emissions from the burning of hydrocarbons or fossil fuels e.g., coal and oil products. Most of the world’s industrialized countries rely on the burning of fossil fuels; power plants, heat homes and provide electricity, automobiles burn gas, and factories burn materials to create products. Air pollution is a serious global problem, and is especially problematic in large urban areas all over the world. Many people suffer from serious illnesses caused by smog and air pollution in these areas. Plants, buildings, and animals are also victims of a particular type of air pollution called acid rain. Acid rain is caused by airborne sulfur from burning coal in power plants and can be transported in rain droplets for thousands of miles. Poisons are then deposited in streams, lakes, and soils, causing damage to wildlife. In addition, acid rain eats into concrete and other solid structures, causing buildings to slowly deteriorate. Scientists study air pollution by breaking the particulates into two different categories of gasses: permanent and variable. The most common of the stable gasses are nitrogen at 78%, and oxygen at 21% of the total atmosphere. Other highly variable gasses are water vapor, carbon dioxide, methane, carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, ammonia, and hydrogen sulfide.


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Output of variable gasses increases with the growth of industrialization and population & their life style. The benefits of progress cost people billions of dollars each year in repairing and preventing air pollution damage. This includes health care and the increased maintenance of structures that are crumbling, in part due to air pollution. The effects of air pollution have to be carefully measured because the buildup of particulates depends on atmospheric conditions and a specific area’s emission level. Once pollutants are released into the atmosphere, wind patterns make it impossible to contain them to any particular region. On the other hand, terrestrial formations such as mountain ridges can act as natural barriers. The terrain and climate of a particular area can also help promote or deflect air pollution. Specifically, weather conditions called thermal inversions can trap the impurities and cause them to build up until they have reached dangerous levels. A thermal inversion is created when a layer of warm air settles over a layer of cool area closer to the ground. It can stay until rain or wind dissipates the layer of stationary warm air. In addition to atmospheric pollution, indoor air pollution also poses special hazards. Some man-made sources of indoor air pollutants include asbestos particulates and formaldehyde vapors — once common building materials now thought to cause cancer. Lead paint is also a problem in older buildings, but its use has been phased out. Other sources of man-made indoor air pollution include improperly vented stoves and heaters, tobacco smoke, and emissions or spillage from pesticides, aerosol sprays, solvents, and disinfectants. 1.5.2 Types & Sources Air Pollution is the human introduction into the atmosphere of chemicals, particulates, or biological materials that cause harm or discomfort to humans or other living organisms, or damage the environment. Air pollution causes deaths and respiratory diseases Air pollution is often identified with major stationary sources. The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on the planet Earth. Stratosphere ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth’s ecosystems. There are many substances in the air, which may impair the health of plants and animals including humans, or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as pollutants. Pollutants can be classified as either primary or secondary. Primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption or the carbon monoxide gas from a motor vehicle exhaust. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone one of the many secondary pollutants that make up photochemical smog. Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.


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Major primary pollutants produced by human activity include: (i) Sulfur oxides (SOx) especially sulfur dioxide are emitted from burning of coal and oil; (ii) Nitrogen oxides (NO x) especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities; (iii) Carbon monoxide is colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide; (iv) Carbon dioxide (CO2), a greenhouse gas emitted from combustion; (v) Volatile organic compounds (VOC), such as hydrocarbons, fuel vapors and solvents; (vi) Particulate matter (PM), measured as smoke and dust. PM10 is the fraction of suspended particles 10 micrometers in diameter and smaller that will enter the nasal cavity. PM2.5 has a maximum particle size of 2.5 μm and will enter the bronchitis and lungs; (vii) Toxic metals, such as lead, cadmium and copper; (viii) Chloral-fluorocarbons (CFCs), harmful to the ozone layer emitted from products currently banned from use; (ix) Ammonia (NH3) emitted from agricultural processes; (x) Odors, such as from garbage, sewage, and industrial processes; (xi) Radioactive pollutants produced by nuclear explosions and was explosives, and natural processes such as radon. Secondary pollutants include: (i) Particulate matter formed from gaseous primary pollutants and compounds in photochemical smog, such as nitrogen dioxide; (ii) Ground level ozone (O 3) formed from NOx and VOCs; (iii) Peroxyacetyl nitrate (PAN) similarly formed from NOx and VOCs. Minor air pollutants: A large number of minor hazardous air pollutants are also released into atmosphere. Some of these are regulated in USA under the Clean Air Act and in Europe under the Air Framework Directive. A variety of persistent organic pollutants can be attached to particulate matter. Sources of air pollution refer to the various locations, activities or factors, which are responsible for the releasing of pollutants in the atmosphere [Annexure I]. These sources can be classified into two major categories, which are: (a) Anthropogenic sources (human activity) mostly related to (i) burning different kinds of fuel; (ii) “Stationary Sources” as smoke stacks of power plants, manufacturing facilities, municipal waste incinerators; (iii) “Mobile Sources” as motor vehicles, aircraft etc.; (iv) Marine vessels, such as container ships or cruise ships, and related port air pollution; (v) Burning wood, fireplaces, stoves, furnaces and incinerators; (vi) Oil refining, and industrial activity in general; (vii) Chemicals, dust and controlled burn practices in agriculture and forestry management; (viii) Fumes from paint, hair spray, varnish, aerosol sprays and other solvents; (ix) Waste deposition in landfills, which generate methane; (x) Military, such as nuclear weapons, toxic gases, germ warfare and rocketry. (b) Natural sources: Dust from natural sources, usually large areas of land with little or no vegetation. Methane, emitted by the digestion of food by animals, for example cattle; Radon gas from radioactive decay within the Earth’s crust; Smoke and carbon monoxide from wildfires; Volcanic activity, which produce sulfur, chlorine, and ash particulates, etc.


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Most Polluted Cities: Air pollution is usually concentrated in densely populated metropolitan areas, especially in developing countries where environmental regulations are generally relatively lax. However, even populated areas in developed countries attain unhealthy levels of pollution. Table 2 presents most polluted cities by particulate matter in 2004. Table 2: Most Polluted Cities by PM in 2004 City

Particulate Matter (mg/m3)

Cairo, Egypt

169

Delhi, India

150

Kolkata, India

128

Tianjin, China

125

Chongqing, China

123

Kanpur, India

109

Lucknow, India

109

Jakarta, Indonesia

104

Shenyang, China

101

Annexure I: Major Air Pollutants Pollutant

Sources

Effects

Ozone. A gas that can be found in two places. Near the ground (the troposphere), it is a major part of smog. The harmful ozone in the lower atmosphere should not be confused with the protective layer of ozone in the upper atmosphere (stratosphere), which screens out harmful ultraviolet rays.

Ozone is not created directly, but is formed when nitrogen oxides and volatile organic compounds mix in sunlight. That is why ozone is mostly found in the summer. Nitrogen oxides come from burning gasoline, coal, or other fossil fuels. There are many types of volatile organic compounds, and they come from sources ranging from factories to trees.

Ozone near the ground can cause a number of health problems. Ozone can lead to more frequent asthma attacks in people who have asthma and can cause sore throats, coughs, and breathing difficulty. It may even lead to premature death. Ozone can also hurt plants and crops.

Carbon monoxide. A gas that comes from the burning of fossil fuels, mostly in cars. It cannot be seen or smelled.

Carbon monoxide is released when engines burn fossil fuels. Emissions are higher when engines are not tuned properly, and when fuel is not completely burned. Cars emit a lot of the carbon monoxide found outdoors. Furnaces and heaters in the home can emit high concentrations of carbon monoxide, too, if they are not properly maintained.

Carbon monoxide makes it hard for body parts to get the oxygen they need to run correctly. Exposure to carbon monoxide makes people feel dizzy and tired and gives them headaches. In high concentrations it is fatal. Elderly people with heart disease are hospitalized more often when they are exposed to higher amounts of carbon monoxide.

Nitrogen dioxide. A reddishbrown gas that comes from the

Nitrogen dioxide mostly comes from power plants and cars.

High levels of nitrogen dioxide exposure can give people coughs


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burning of fossil fuels. It has a strong smell at high levels.

Nitrogen dioxide is formed in two ways—when nitrogen in the fuel is burned, or when nitrogen in the air reacts with oxygen at very high temperatures. Nitrogen dioxide can also react in the atmosphere to form ozone, acid rain, and particles.

and can make them feel short of breath. People who are exposed to nitrogen dioxide for a long time have a higher chance of getting respiratory infections. Nitrogen dioxide reacts in the atmosphere to form acid rain, which can harm plants and animals.

Particulate matter. Solid or liquid matter that is suspended in the air. To remain in the air, particles usually must be less than 0.1-mm wide and can be as small as 0.00005 mm.

Particulate matter can be divided into two types—coarse particles and fine particles. Coarse particles are formed from sources like road dust, sea spray, and construction. Fine particles are formed when fuel is burned in automobiles and power plants.

Particulate matter that is small enough can enter the lungs and cause health problems. Some of these problems include more frequent asthma attacks, respiratory problems, and premature death.

Sulfur dioxide. A corrosive gas that cannot be seen or smelled at low levels but can have a “rotten egg” smell at high levels.

Sulfur dioxide mostly comes from the burning of coal or oil in power plants. It also comes from factories that make chemicals, paper, or fuel. Like nitrogen dioxide, sulfur dioxide reacts in the atmosphere to form acid rain and particles.

Sulfur dioxide exposure can affect people who have asthma or emphysema by making it more difficult for them to breathe. It can also irritate people’s eyes, noses, and throats. Sulfur dioxide can harm trees and crops, damage buildings, and make it harder for people to see long distances.

Lead. A blue-gray metal that is very toxic and is found in a number of forms and locations.

Outside, lead comes from cars in areas where unleaded gasoline is not used. Lead can also come from power plants and other industrial sources. Inside, lead paint is an important source of lead, especially in houses where paint is peeling. Lead in old pipes can also be a source of lead in drinking water.

High amounts of lead can be dangerous for small children and can lead to lower IQs and kidney problems. For adults, exposure to lead can increase the chance of having heart attacks or strokes.

Toxic air pollutants. A large number of chemicals that are known or suspected to cause cancer. Some important pollutants in this category include arsenic, asbestos, benzene, and dioxin.

Each toxic air pollutant comes from a slightly different source, but many are created in chemical plants or are emitted when fossil fuels are burned. Some toxic air pollutants, like asbestos and formaldehyde, can be found in building materials and can lead to indoor air problems. Many toxic air pollutants can also enter the food and water supplies.

Toxic air pollutants can cause cancer. Some toxic air pollutants can also cause birth defects. Other effects depend on the pollutant, but can include skin and eye irritation and breathing problems.

Stratospheric ozone depleters. Chemicals that can destroy the ozone in the stratosphere. These

CFCs are used in air conditioners and refrigerators, since they work well as coolants. They can also

If the ozone in the stratosphere is destroyed, people are exposed to more radiation from the sun


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chemicals include chlorofluorocarbons (CFCs), halons, and other compounds that include chlorine or bromine.

be found in aerosol cans and fire extinguishers. Other stratospheric ozone depleters are used as solvents in industry.

(ultraviolet radiation). This can lead to skin cancer and eye problems. Higher ultraviolet radiation can also harm plants and animals.

Greenhouse gases. Gases that stay in the air for a long time and warm up the planet by trapping sunlight. This is called the “greenhouse effect” because the gases act like the glass in a greenhouse. Some of the important greenhouse gases are carbon dioxide, methane, and nitrous oxide.

Carbon dioxide is the most important greenhouse gas. It comes from the burning of fossil fuels in cars, power plants, houses, and industry. Methane is released during the processing of fossil fuels, and also comes from natural sources like cows and rice paddies. Nitrous oxide comes from industrial sources and decaying plants.

The greenhouse effect can lead to changes in the climate of the planet. Some of these changes might include more temperature extremes, higher sea levels; changes in forest composition, and damage to land near the coast. Human health might be affected by diseases that are related to temperature or by damage to land and water.

Source: Jonathan Levy, Harvard School of Public Health. Based on information provided by the Environmental Protection Agency.


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Chapter 2

Ozone Depletion 2.1

What is Ozone?

Ozone is a form of oxygen. Oxygen occurs in three different forms in the atmosphere, namely as atoms (O), as molecules (O2) and as ozone (O3). Ozone’s unique physical properties allow the ozone layer to act as our planet’s sunscreen, providing an invisible filter to help protect all life forms from the Sun’s damaging UV (ultraviolet) rays. Most incoming UV radiation is absorbed by ozone and prevented from reaching the Earth’s surface. Without the protective effect of ozone, life on the Earth would not have evolved the way it has. The Sun emits a range of energy known as the electromagnetic spectrum [Figure 2a]. The various forms of energy, or radiation, are classified according to wavelength (measured in nanometers where one nm is a millionth of a millimeter). The shorter the wavelength, the more energetic is the radiation. In order of decreasing energy, the principal forms of radiation are gamma rays, x-rays, UV (ultraviolet radiation), visible light, infrared radiation, microwaves, and radio waves. Ultraviolet, which is invisible, is so named because it occurs next to violet in the visible light spectrum. UV radiation is divided into three categories as: UV-A between 320 and 400 nm; UV-B between 280 and 320 nm; UV-C between 200 and 280 nm. Of these UV-B and C being highly energetic and are dangerous to life on the Earth. UV-A being less energetic is not dangerous. Fortunately, UV-C is absorbed strongly by oxygen and also by ozone in the upper atmosphere. UV-B is also absorbed by ozone layer in the Stratosphere and only 2-3% of it reaches the Earth’s surface. The ozone Layer, therefore, is highly beneficial to plant and animal life on the Earth in filtering out the dangerous part of the Sun’s radiation and allowing only the beneficial part to reach the Earth. Any disturbance or depletion of this layer would result in an increase UV-B and UV-C radiation reaching the Earth’s surface leading to dangerous consequences. 2.2

History of Ozone Research

Sydney Chapman discovered the basic physical and chemical processes that lead to the formation of an ozone layer in the Earth’s stratosphere in 1930. These are discussed in the article Ozone-oxygen cycle — briefly, short-wavelength UV radiation splits an oxygen (O2) molecule into two oxygen (O) atoms, which then combine with other oxygen molecules to form ozone. Ozone is removed when an oxygen atom and an ozone molecule “recombine” to form two oxygen molecules, i.e. O + O3 = 2O2. In the 1950s, David Bates and Marcel Nicolet presented evidence that various free radicals, in particular hydroxyl (OH) and nitric oxide (NO), could catalyze this recombination reaction, reducing the overall amount of ozone. These free radicals were known to be present in the stratosphere, and so were regarded as part of the


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18



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natural balance – it was estimated that in their absence, the ozone layer would be about twice as thick as it currently is. In 1970 Prof. Paul Crutzen pointed out that emissions of nitrous oxide (N2O), a stable, long-lived gas produced by soil bacteria, from the Earth’s surface could affect the amount of nitric oxide (NO) in the stratosphere. Crutzen showed that nitrous oxide lives long enough to reach the stratosphere, where it is converted into NO. Crutzen then noted that increasing use of fertilizers might have led to an increase in nitrous oxide emissions over the natural background, which would in turn result in an increase in the amount of NO in the stratosphere. Thus human activity could have an impact on the stratospheric ozone layer. In the following year, Crutzen and (independently) Harold Johnston suggested that NO emissions from supersonic aircraft, which fly in the lower stratosphere, could also deplete the ozone layer. In 1974 Frank Sherwood Rowland, Chemistry Professor at the University of California at Irvine, and his postdoctoral associate Mario J. Molina suggested that long-lived organic halogen compounds, such as CFCs, might behave in a similar fashion as Crutzen had proposed for nitrous oxide. James Lovelock (most popularly known as the creator of the Gaia hypothesis] had discovered, during a cruise in the South Atlantic in 1971, that almost all of the CFC compounds manufactured since their invention in 1930 were still present in the atmosphere. Molina and Rowland concluded that, like N2O, the CFCs would reach the stratosphere where they would be dissociated by UV light, releasing Cl atoms. A year earlier, Richard Stolarski and Ralph Cicerone at the University of Michigan had shown that Cl is even more efficient than NO at catalyzing the destruction of ozone. Michael McElroy and Steven Wofsy at Harvard University reached similar conclusions. Neither group, however, had realized that CFC’s were a potentially large source of stratospheric chlorine — instead, they had been investigating the possible effects of HCl emissions from the Space Shuttle, which are very much smaller. The Rowland-Molina hypothesis was strongly disputed by representatives of the aerosol and halocarbon industries. The Chair of the Board of DuPont was quoted as saying that ozone depletion theory is “a science fiction tale...a load of rubbish...utter nonsense”. Robert Abplanalp, the President of Precision Valve Corporation (and inventor of the first practical aerosol spray can valve), wrote to the Chancellor of UC Irvine to complain about Rowland’s public statements. Nevertheless, within three years most of the basic assumptions made by Rowland and Molina were confirmed by laboratory measure-ments and by direct observation in the stratosphere. The concentrations of the source gases (CFC’s and related compounds) and the chlorine reservoir species (HCl and ClONO2) were measured throughout the strato-sphere, and demonstrated that CFCs were indeed the major source of stratospheric chlorine, and that nearly all of the CFCs emitted would eventually reach the stratosphere. Even more convincing was the measurement, by James G. Anderson and collaborators, of chlorine monoxide (ClO) in the stratosphere. ClO is


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produced by the reaction of Cl with ozone — its observation thus demonstrated that Cl radicals not only were present in the stratosphere but also were actually involved in destroying ozone. McElroy and Wofsy extended the work of Rowland and Molina by showing that Bromine atoms were even more effective catalysts for ozone loss than chlorine atoms and argued that the brominated organic compounds known as halons, widely used in fire extinguishers, were a potentially large source of stratospheric bromine. In 1976 the U.S. National Academy of Sciences released a report, which concluded that the ozone depletion hypothesis was strongly supported by the scientific evidence. Scientists calculated that if CFC production continued to increase at the going rate of 10% per year until 1990 and then remain steady, CFCs would cause a global ozone loss of 5 to 7% by 1995, and a 30 to 50% loss by 2050. In response the United States, Canada, Sweden and Norway banned the use of CFCs in aerosol spray cans in 1978. However, subsequent research, summarized by the National Academy in reports issued between 1979 and 1984, appeared to show that the earlier estimates of global ozone loss had been too large. 2.3

Ozone Depletion

Ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is tipped in favour of destruction. Although natural phenomenon can cause temporary ozone loss, chlorine and bromine released from synthetic compounds is now accepted as the main cause of a net loss of stratospheric ozone in many parts of the world since 1980. Ozone is formed in the stratosphere when oxygen molecules photo-dissociate after absorbing an ultraviolet photon whose wavelength is shorter than 240 nm. This produces two oxygen atoms. The atomic oxygen then combines with O2 to create O3. Ozone molecules absorb UV light between 310 and 200 nm, following which ozone splits into a molecule of O2 and an oxygen atom. The oxygen atom then joins up with an oxygen molecule to regenerate ozone. This is a continuing process which terminates when an oxygen atom “recombines” with an ozone molecule to make two O2 molecules: O + O3 −−> 2 O2. A balance between photochemical production and recombination process determines the overall amount of ozone present in the stratosphere. Ozone can be destroyed by a number of free radical catalysts, the most important of which are the hydroxyl radical (OH), the nitric-oxide radical (NO) and atomic chlorine (Cl) and bromine (Br). All of these have both natural and anthropogenic (manmade) sources [Figure 2 b]; at the present time, most of the OH and NO in the stratosphere is of natural origin, but human activity has dramatically increased the high in oxygen chlorine and bromine. These elements are found in certain stable organic compounds, especially chlorofluorocarbons (CFCs), which may find their way to the stratosphere without being destroyed in the troposphere due to their low reactivity. Once in the stratosphere, the Cl and Br atoms are liberated from the parent compounds by the action of ultraviolet light. The Cl and Br atoms can then destroy ozone molecules through a variety of catalytic


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cycles. In the simplest example of such a cycle, a chlorine atom reacts with an ozone molecule, taking an oxygen atom with it (forming ClO) and leaving a normal oxygen molecule. A free oxygen atom then takes away the oxygen from the ClO, and the final result is an oxygen molecule and a chlorine atom, which then reinitiates the cycle. The overall effect is to increase the rate of recombination, leading to an overall decrease in the amount of ozone. For this particular mechanism to operate there must be a source of O atoms, which is primarily the photo dissociation of O3; thus this mechanism is only important in the upper stratosphere where such atoms are abundant. More complicated mechanisms have been discovered that lead to ozone destruction in the lower stratosphere as well (discussed in previous chapter). A single chlorine atom would keep on destroying ozone for up to two years (the time scale for transport back down to the troposphere) were it not for reactions that remove them from this cycle by forming reservoir species such as hydrogen chloride (HCl) and chlorine nitrate (ClONO2). On a per atom basis, bromine is even more efficient than chlorine at destroying ozone, but there is much less bromine in the atmosphere at present. As a result, both chlorine and bromine contribute significantly to the overall ozone depletion. Laboratory studies have shown that fluorine and iodine atoms participate in analogous catalytic cycles. However, in the Earth’s stratosphere, fluorine atoms react rapidly with water and methane to form strongly bound hydrofluoric acid, while organic molecules which contain iodine react so rapidly in the lower atmosphere that they do not reach the stratosphere in significant quantities. Furthermore, a single chlorine atom is able to react with 100,000 ozone molecules. This fact plus the amount of chlorine released into the atmosphere by chlorofluorocarbons (CFCs) yearly demonstrates how dangerous CFCs are to the environment. 2.4

The Ozone Hole

History: The discovery of the Antarctic “ozone hole” by British Atlantic Survey scientists Farman, Gardiner and Shanklin (announced in a paper in Nature in May 1985) came as a shock to the scientific community, because the observed decline in polar ozone was far larger than anyone had anticipated. Satellite measurements showing massive depletion of ozone around the South Pole were becoming available at the same time. However, these were initially rejected as unreasonable by data quality control algorithms (they were filtered out as errors since the values were unexpectedly low); the ozone hole was detected only in satellite data when the raw data was reprocessed following evidence of ozone depletion in in situ observations. When the software was rerun without the flags, the ozone hole was seen as far back as 1976. Susan Solomon, an atmospheric chemist at the National Oceanic and Atmospheric Administration (NOAA), proposed that chemical reactions on Polar Stratospheric Clouds (PSCs) in the cold Antarctic stratosphere caused a massive, though localized and seasonal, increase in the amount of chlorine present in active, ozone-destroying forms. The PSCs in Antarctica are only formed when there are


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very low temperatures, as low as -80 oC, and early spring conditions. In such conditions the ice crystals of the cloud provide a suitable surface for conversion of non-reactive chlorine compounds into reactive chlorine compounds, which can deplete ozone easily. Moreover the polar vortex formed over Antarctica is very tight and the reaction, which occurs on the surface of the cloud crystals, is far different from when it occurs in atmosphere. These conditions have led to ozone hole formation in Antarctica. This hypothesis was decisively confirmed, first by laboratory measurements and subsequently by direct measurements, from the ground and from high-altitude airplanes, of very high concentrations of chlorine monoxide (ClO) in the Antarctic stratosphere. Alternative hypotheses, which had attributed the ozone hole to variations in solar UV radiation or to changes in atmospheric circulation patterns, were also tested and shown to be untenable. However, the vortex formation and consequent reduction in temperature is the part of atmospheric circulation only. This is the region for the differences in ozone depletion at south and north pole. Meanwhile, analysis of ozone measurements from the worldwide network of ground-based Dobson spectrophotometers led an international panel to conclude that the ozone layer was in fact being depleted, at all latitudes outside of the tropics. These trends were confirmed by satellite measurements. As a consequence, the major halocarbon producing nations agreed to phase out production of CFCs, halons, and related compounds, a process that was completed in 1996. Crutzen, Molina, and Rowland were awarded the 1995 Nobel Prize in Chemistry for their work on stratospheric ozone. When the “ozone hole” forms, essentially all of the ozone in the lower stratosphere is destroyed. The upper stratosphere is much less affected, however, so that the overall amount of ozone over the continent declines by 50 percent or more. The ozone hole does not go all the way through the layer; on the other hand, it is not a uniform ‘thinning’ of the layer either. It’s a “hole” in the sense of “a hole in the ground”, a depression, not in the sense of “a hole in the windshield”. G.M.B. Dobson (Exploring the Atmosphere, 2nd Edition, Oxford, 1968) mentioned that when springtime ozone levels over Halley Bay were first measured, he was surprised to find that they were ~320 DU, about 150 DU below spring levels, ~450 DU, in the Arctic. These, however, were the pre-ozone-hole normal climatological values. What Dobson describes is essentially the baseline from which the ozone hole is measured: actual ozone hole values are in the 150–100 DU range. The discrepancy between the Arctic and Antarctic noted by Dobson was primarily a matter of timing: during the Arctic spring ozone levels rose smoothly, peaking in April, whereas in the Antarctic they stayed approximately constant during early spring, rising abruptly in November when the polar vortex broke down. The behavior seen in the Antarctic ozone hole is completely different. Instead of staying constant, early springtime ozone levels suddenly drop from their already low winter values, by as much as 50%, and normal values are not reached again until December. If the theory were correct, the ozone hole should be above the


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sources of CFCs. The CFCs are well mixed in the troposphere and the stratosphere. The reason the ozone hole occurs above Antarctica is not because there are more CFCs there but because the low temperatures allow polar stratospheric clouds to form. There have been anomalous discoveries of significant, serious, localized “holes” above other parts of the globe. It is sometimes stated that since CFC molecules are much heavier than nitrogen or oxygen, they cannot reach the stratosphere in significant quantities. But atmospheric gases are not sorted by weight; the forces of wind (turbulence) are strong enough to fully intermix gases in the atmosphere. CFCs are heavier than air, but just like argon, krypton and other heavy gases with a long lifetime, they are uniformly distributed throughout the turbosphere and reach the upper atmosphere.Since 1981 the UNEP has sponsored a series of reports on scientific assessment of ozone depletion. The most recent is from 2007 where satellite measurements have shown the hole in the ozone layer is recovering and is now the smallest it has been for about a decade. Ozone Hole Process: The Antarctic ozone hole is an area of the Antarctic stratosphere in which the recent ozone levels have dropped to as low as 33% of their pre-1975 values. The ozone hole occurs during the Antarctic spring, from September to early December, as strong westerly winds start to circulate around the continent and create an atmospheric container. Within this polar vortex, over 50% of the lower stratospheric ozone is destroyed during the Antarctic spring. As explained above, the overall cause of ozone depletion is the presence of chlorine containing source gases (primarily CFCs and related halocarbons). In the presence of UV light, these gases dissociate, releasing chlorine atoms, which then go on to catalyze ozone destruction. The Cl catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds (PSCs). These polar stratospheric clouds form during winter, in the extreme cold. Polar winters are dark, consisting of 3 months without solar radiation (sunlight). Not only lack of sunlight contributes to a decrease in temperature but also the polar vortex traps and chills air. Temperatures hover around or below -80 °C. These low temperatures form cloud particles and are composed of either nitric acid (Type I PSC) or ice (Type II PSC). Both types provide surfaces for chemical reactions that lead to ozone destruction. The photochemical processes involved are complex but well understood. The key observation is that, ordinarily, most of the chlorine in the stratosphere resides in stable “reservoir” compounds, primarily hydrogen chloride (HCl) and chlorine nitrate (ClONO2). During the Antarctic winter and spring, however, reactions on the surface of the polar stratospheric cloud particles convert these “reservoir” compounds into reactive free radicals (Cl and ClO). The clouds can also remove NO2 from the atmosphere by converting it to nitric acid, which prevents the newly formed ClO from being converted back into ClONO2. The role of sunlight in ozone depletion is the reason why the Antarctic ozone depletion is greatest during spring. During winter, even though PSCs are at their


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most abundant, there is no light over the pole to drive the chemical reactions. During the spring, however, the sun comes out, providing energy to drive photochemical reactions, and melt the polar stratospheric clouds, releasing the trapped compounds. Most of the ozone that is destroyed is in the lower stratosphere, in contrast to the much smaller ozone depletion through homogeneous gas phase reactions, which occurs primarily in the upper stratosphere. Warming temperatures near the end of spring break up the vortex around mid-December. As warm, ozone-rich air flows in from lower latitudes, the PSCs are destroyed, the ozone depletion process shuts down, and the ozone hole heals. While the effect of the Antarctic ozone hole in decreasing the global ozone is relatively small, estimated at about 4% per decade, the hole has generated a great deal of interest because the decrease in the ozone layer was predicted in the early 1980s to be roughly 7% over a sixty-year period. The sudden recognition in 1985 that there was a substantial “hole” was widely reported in the press. The


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especially rapid ozone depletion in Antarctica had previously been dismissed as a measurement error. Many were worried that ozone holes might start to appear over other areas of the globe but to date the only other large-scale depletion is a smaller ozone “dimple” observed during the Arctic spring over the North Pole. Ozone at middle latitudes has declined, but by a much smaller extent (about 4–5% decrease). If the conditions became more severe (cooler stratospheric temperatures, more stratospheric clouds, more active chlorine), then global ozone may decrease at a much greater pace. Standard global warming theory predicts that the stratosphere will cool. When the Antarctic ozone hole breaks up, the ozone-depleted air drifts out into nearby areas. Decreases in the ozone level of up to 10% have been reported in New Zealand in the month following the breakup of the Antarctic ozone hole. Ozone Hole: The terms “ozone hole” refers to a large and rapid decrease in the abundance of ozone molecules, not the complete absence of them. The Antarctic “ozone hole” occurs during the southern spring between September and November. The British Antarctic Survey Team first reported it in May 1985. The Team found that for the period between September and mid November, ozone concentrations over Halley Bay, Antarctica, had declined 40% from levels during the 1960s. Severe depletion had been occurring since the late 1970s. Lowest value of ozone measured


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by TOMS each year in the ozone hole is given in Figure 2c. Figure 2d presents the September 2006 image of the largest Antarctic ozone hole ever recorded. Figure 2e presents the annual March of Spring (September to December) and Summer (January to March) Antarctic total ozone based on four locations observations,

namely Argentina Island, Syowa, Halley Bay and the South Pole (WMO, Fact Sheet). Figure 2f presents the annual march of Winter (December to March) and Summer (May to August) Arctic total ozone from the combined long-term mean of 12 stations North of 59 oN. Figure 2g presents the seasonal change of Antarctic ozone at Argentina Island, Syowa and Halley Bay. The figures represent the change during 1979-86 as % of the 1957-78. Figure 2h presents the annual march of total ozone as deviation from the long-term average for four latitudinal zones of the Northern Hemisphere (from top to bottom — 80-60, 64-53, 52-40 & 3930 oN) for Winter-Spring (December to March) and for Summer (May to August) – on the right side of each chart, the numbers indicate the long-term mean value for each zone in Dobson units. Reductions of up to 70% in the ozone column


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observed in the austral (Southern Hemispheric) spring over Antarctica and first reported in 1985 are continuing. Through the 1990s, total column ozone in September and October have continued to be 40–50% lower than pre-ozone-hole values. In the Arctic the amount lost is more variable year-to-year than in the Antarctic. The greatest declines, up to 30%, are in the Winter and Spring, when the stratosphere is colder. In middle latitudes it is preferable to speak of ozone depletion rather than holes. Declines are about 3% below pre-1980 values for 35– 60°N and about 6% for 35–60°S. In the tropics, there are no significant trends. Predictions of ozone levels remain difficult. The WMO/UN Global Ozone Research and Monitoring Project – Report No. 44 comes out strongly in favor for the Montreal Protocol, but notes that a UNEP 1994 Assessment overestimated ozone loss for the 1994–1997 period. Is UVB increasing at surface?: Since the ozone layer absorbs UVB ultraviolet light from the Sun, ozone layer depletion is expected to increase surface UVB levels,


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which could lead to damage, including increases in skin cancer. This was the reason for the Montreal Protocol. Although decreases in stratospheric ozone are well-tied to CFCs and there are good theoretical reasons to believe that decreases in ozone will lead to increases in surface UVB, there is no direct observational evidence linking ozone depletion to higher incidence of skin cancer in human beings. This is partly due to the fact that UVA, which has also been implicated in some forms of skin cancer, is not absorbed by ozone, and it is nearly impossible to control statistics for lifestyle changes in the populace. 2.5

Ozone and Policy

That ozone depletion takes place is not seriously disputed in the scientific community. There is a consensus among atmospheric physicists and chemists that the scientific understanding has now reached a level where counter-measures to control CFC emissions are justified, although the decision is ultimately one for policy-makers. Despite this consensus, the science behind ozone depletion remains complex, and some who oppose the enforcement of countermeasures point to some of the uncertainties. For example, although increased UVB has been shown to constitute a melanoma risk, it has been difficult for statistical studies to establish a direct link between ozone depletion and increased rates of melanoma. Although melanomas did increase significantly during the period 1970–1990, it is difficult to separate reliably the effect of ozone depletion from the effect of changes in lifestyle factors (e.g., increasing rates of air travel. The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine. The main source of these halogen atoms in the stratosphere is photo-dissociation of chlorofluorocarbons (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased. Thomas Midgley invented Chlorofluorocarbons (CFCs) in the 1930s. They were used in Air Conditioning/cooling units, as aerosol spray propellants prior to the 1980s, and in the cleaning processes of delicate electronic equipment. They also occur as by-products of some chemical processes. No significant natural sources have ever been identified for these compounds — their presence in the atmosphere is due almost entirely to human manufacture. When such ozonedepleting chemicals reach the stratosphere, they are dissociated by ultraviolet light to release chlorine atoms. The chlorine atoms act as a catalyst, and each can break down tens of thousands of ozone molecules before being removed from the stratosphere. Given the longevity of CFC molecules, recovery times are measured in decades. It is calculated that a CFC molecule takes an average of 15 years to go from the ground level up to the upper atmosphere, and it can stay there for about a century, destroying up to one hundred thousand ozone molecules during that time.


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CFCs and other contributory substances are commonly referred to as ozonedepleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through the Earth’s atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol banning the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increase in skin cancer, damage to plants, and reduction of plankton populations in the ocean’s photic zone may result from the increased UV exposure due to ozone depletion. 2.6

International Action

The first international action to focus attention on the dangers of ozone depletion in the stratosphere and its dangerous consequences in the long run on life on earth was focused in 1977 when in a meeting of 32 countries in Washington D.C. a World plan on action on Ozone layer with UNEP as the coordinator was adopted. As experts began their investigation, data piled up and in 1985 in an article published in the science journal, “Nature” by Dr. Farman pointed out that although there is overall depletion of the ozone layer all over the world, the most severe depletion had taken place over the Antarctica. This is what is famously called as “the Antarctica Ozone hole”. His findings were confirmed by Satellite observations and offered the first proof of severe ozone depletion and stirred the scientific community to take urgent remedial actions in an international convention held in Vienna on March 22, 1985. This resulted in an international agreement in 1987 on specific measures to be taken in the form of an international treaty known as the “Montreal Protocol” on Substances That Deplete the Ozone Layer. Under this Protocol the first concrete step to save the Ozone layer was taken by immediately agreeing to completely phase out chlorofluoro-carbons (CFC), Halons, Carbon tetrachloride (CTC) and Methyl chloroform (MCF) as per a schedule. 2.6.1 Alternative Substances In 1985 around 20 nations, including most of the major CFC producers, signed the Vienna Convention, which established a framework for negotiating international regulations on ozone-depleting substances. That same year, the discovery of the Antarctic ozone hole was announced, causing a revival in public attention to the issue. In 1987, representatives from 43 nations signed the Montreal Protocol. Meanwhile, the halocarbon industry shifted its position and started supporting a protocol to limit CFC production. The reasons for this were in part explained by “Dr. Mostafa Tolba, former head of the UN Environment Programme, who was quoted in the June 30, 1990 edition of The New Scientist, ‘...the chemical industry supported the Montreal Protocol in 1987 because it set up a worldwide schedule for phasing out CFCs, which [were] no longer protected by patents. This provided companies with an equal opportunity to market new, more profitable compounds”.


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At Montreal, the participants agreed to freeze production of CFCs at 1986 levels and to reduce production by 50% by 1999. After a series of scientific expeditions to the Antarctic produced convincing evidence that the ozone hole was indeed caused by chlorine and bromine from manmade organohalogens, the Montreal Protocol was strengthened at a 1990 meeting in London. The participants agreed to phase out CFCs and halons entirely (aside from a very small amount marked for certain “essential” uses, such as asthma inhalers) by 2000. At a 1992 meeting in Copenhagen, the phase out date was moved up to 1996. To some extent, CFCs have been replaced by the less damaging hydrochlorofluorocarbons (HCFCs), although concerns remain regarding HCFCs also. In some applications, hydro-fluorocarbons (HFCs) have been used to replace CFCs. HFCs, which contain no chlorine or bromine, do not contribute at all to ozone depletion although they are potent greenhouse gases. The best known of these compounds is probably HFC-134a (R-134a), which in the United States has largely replaced CFC-12 (R-12) in automobile air conditioners. In laboratory analytics (a former “essential” use) the ozone depleting substances can be replaced with various other solvents. Ozone Diplomacy, by Richard Benedick (Harvard University Press, 1991) gives a detailed account of the negotiation process that led to the Montreal Protocol. Pielke and Betsill provide an extensive review of early US government responses to the emerging science of ozone depletion by CFCs. 2.6.2 Ozone-depleting gas trends Since the adoption and strengthening of the Montreal Protocol has led to reductions in the emissions of CFCs, atmospheric concentrations of the most significant compounds have been declining. These substances are being gradually removed from the atmosphere. By 2015, the Antarctic ozone hole would have reduced by only 1 million km² out of 25 (Newman et al., 2004); complete recovery of the Antarctic ozone layer will not occur until the year 2050 or later. Work has suggested that a detectable (and statistically significant) recovery will not occur until around 2024, with ozone levels recovering to 1980 levels by around 2068. There is a slight caveat to this, however “Global warming from CO2 is expected to cool the stratosphere. This, in turn, would lead to a relative increase in ozone depletion and the frequency of ozone holes. The effect may not be linear; ozone holes form because of polar stratospheric clouds; the formation of polar stratospheric clouds has a temperature threshold above which they will not form; cooling of the Arctic stratosphere might lead to Antarctic-ozone-hole-like conditions. But at the moment this is not clear”. Even though the stratosphere as a whole is cooling, high-latitude areas may become increasingly predisposed to springtime stratospheric warming events as weather patterns change in response to higher greenhouse gas loading. This would cause PSCs to disappear earlier in the season, and may explain why Antarctic ozone hole seasons have tended to end somewhat earlier since 2000 as compared with the most prolonged ozone holes of the 1990s. The decrease in ozone-depleting


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chemicals has also been significantly affected by a decrease in bromine-containing chemicals. The data suggest that substantial natural sources exist for atmospheric methyl bromine (CH3Br). The 2004 ozone hole ended in November 2004, daily minimum stratospheric temperatures in the Antarctic lower stratosphere increased to levels that are too warm for the formation of polar stratospheric clouds (PSCs) about 2 to 3 weeks earlier than in most recent years. The Arctic winter of 2005 was extremely cold in the stratosphere; PSCs were abundant over many high-latitude areas until dissipated by a big warming event, which started in the upper stratosphere during February and spread throughout the Arctic stratosphere in March. The size of the Arctic area of anomalously low total ozone in 2004-2005 was larger than in any year since 1997. The predominance of anomalously low total ozone values in the Arctic region in the winter of 2004-2005 is attributed to the very low stratospheric temperatures and meteorological conditions favorable for ozone destruction along with the continued presence of ozone destroying chemicals in the stratosphere. A 2005 IPCC summary of ozone issues observed that observations and model calculations suggest that the global average amount of ozone depletion has now approximately stabilized. Although considerable variability in ozone is expected from year to year, including in polar regions where depletion is largest, the ozone layer is expected to begin to recover in coming decades due to declining ozonedepleting substance concentrations, assuming full compliance with the Montreal Protocol. Temperatures during the Arctic winter of 2006 stayed fairly close to the long-term average until late January, with minimum readings frequently cold enough to produce PSCs. During the last week of January, however, a major warming event sent temperatures well above normal — much too warm to support PSCs. By the time temperatures dropped back to near normal in March, the seasonal norm was well above the PSC threshold. Preliminary satellite instrument-generated ozone maps show seasonal ozone buildup slightly below the long-term means for the Northern Hemisphere as a whole, although some high ozone events have occurred. During March 2006, the Arctic stratosphere pole-ward of 60 degrees North Latitude was free of anomalously low ozone areas except during the three-day period from March 17 to 19 when the total ozone cover fell below 300 DU over part of the North Atlantic region from Greenland to Scandinavia. The area where total column ozone is less than 220 DU (the accepted definition of the boundary of the ozone hole) was relatively small until around 20 August 2006. Since then the ozone hole area increased rapidly, peaking at 29 million km² September 24. In October 2006, NASA reported that the year’s ozone hole set a new area record with a daily average of 26 million km² between 7 September and 13 October 2006; total ozone thickness fell as low as 85 DU on October 8. The two factors combined, 2006 sees the worst level of depletion in recorded ozone history. The depletion is attributed to the temperatures above the Antarctic reaching the lowest recording since comprehensive records began in 1979.


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The Antarctic ozone hole is expected to continue for decades. Ozone concentrations in the lower stratosphere over Antarctica will increase by 5%–10% by 2020 and return to pre-1980 levels by about 2060–2075, 10–25 years later than predicted in earlier assessments. This is because of revised estimates of atmospheric concentrations of Ozone Depleting Substances — and a larger predicted future usage in developing countries. Another factor, which may aggravate ozone depletion, is the drawdown of nitrogen oxides from above the stratosphere due to changing wind patterns. 2.6.3 Man-made chlorine vs natural source Another objection occasionally voiced is that “It is generally agreed that natural sources of tropospheric chlorine (volcanoes, ocean spray, etc.) are four to five orders of magnitude larger than man-made sources”. While strictly true, tropospheric chlorine is irrelevant; it is stratospheric chlorine that matters to ozone depletion. Chlorine from ocean spray is soluble and thus is washed out by rainfall before it reaches the stratosphere. CFCs, in contrast, are insoluble and long-lived, which allows them to reach the stratosphere. Even in the lower atmosphere there is more chlorine present in the form of CFCs and related haloalkanes than there is in HCl from salt spray, and in the stratosphere the halocarbons dominate overwhelmingly. Only one of these halocarbons, methyl chloride, has a predominantly natural source, and it is responsible for about 20 percent of the chlorine in the stratosphere; the remaining 80% comes from manmade compounds. Very large volcanic eruptions can inject HCl directly into the stratosphere, but direct measurements have shown that their contribution is small compared to that of chlorine from CFCs. A similar erroneous assertion is that soluble halogen compounds from the volcanic plume of Mount Erebus on Ross Island, Antarctica are a major contributor to the Antarctic ozone hole. 2.6.4 World Ozone Day In 1994, the United Nations General Assembly voted to designate September 16 as “World Ozone Day”, to commemorate the signing of the Montreal Protocol on that date in 1987. On the ozone depletion theory, though initially there was some opposition, more particularly from the industry lobby, latter it was accepted. This has leads in finding alternate substances to arrest this trend. However, the long life of the ozone depleting substances in the atmosphere, it may take time to stabilize the ozone process to pre-ozone depleting substances level. This is success story of science. 2.7

Impact on Environment

2.7.1 Effects on life forms on the Earth A recent assessment made by a panel of UNEP experts gives a detailed account of the impacts of ozone depletion on human health, animals, plants, microorganisms, materials and air quality.


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Effects on Human & Animal Health: Increased penetration of solar UV-B radiation is likely to have profound impact on human health with potential risks of eye diseases, skin cancer and infectious diseases. UV radiation is known to damage the cornea and lens of the eye. Chronic exposure to UV-B could lead to cataract of the cortical and posterior subcapsular forms. UV-B radiation can adversely affect the immune system causing a number of infectious diseases. In light skinned human populations, it is likely to develop nonmelanoma skin cancer (NMSC). Experiments on animals show that UV exposure decreases the immune response to skin cancers, infectious agents and other antigens Effects on Terrestrial Plants: It is a known fact that the physiological and developmental processes of plants are affected by UV-B radiation. Scientists believe that an increase in UV-B levels would necessitate using more UV-B tolerant cultivar and breeding new tolerant ones in agriculture. In forests and grasslands increased UV-B radiation is likely to result in changes in species composition (mutation) thus altering the bio-diversity in different ecosystems. UV-B could also affect the plant community indirectly resulting in changes in plant form, secondary metabolism, etc. These changes can have important implications for plant competitive balance, plant pathogens and bio-geochemical cycles. Effects on Aquatic Ecosystems: While more than 30 percent of the world’s animal protein for human consumption comes from the sea alone, it is feared that increased levels of UV exposure can have adverse impacts on the productivity of aquatic systems. High levels of exposure in tropics and subtropics may affect the distribution of phytoplanktons which form the foundation of aquatic food webs. Reportedly a recent study has indicated 6-12 percent reduction in phytoplankton production in the marginal ice zone due to increases in UV-B. UV-B can also cause damage to early development stages of fish, shrimp, crab, amphibians and other animals, the most severe effects being decreased reproductive capacity and impaired larval development. Effects on Bio-geo-chemical Cycles: Increased solar UV radiation could affect terrestrial and aquatic bio-geo-chemical cycles thus altering both sources and sinks of greenhouse and important trace gases, e.g. carbon dioxide (CO 2), carbon monoxide (CO), carbonyl sulphide (COS), etc. These changes would contribute to biosphere-atmosphere feedbacks responsible for the atmosphere build-up of these gases. Other effects of increased UV-B radiation include: changes in the production and decomposition of plant matter; reduction of primary production changes in the uptake and release of important atmospheric gases; reduction of bacterioplankton growth in the upper ocean; increased degradation of aquatic dissolved organic matter (DOM), etc. Aquatic nitrogen cycling can be affected by enhanced UV-B through inhibition of nitrifying bacteria and photo-decomposition of simple inorganic species such as nitrate. The marine sulphur cycle may also be affected resulting in possible changes in the sea-to-air emissions of COS and


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dimethylsulfied (DMS), two gases that are degraded to sulphate aerosols in the stratosphere and troposphere, respectively. Effects on Air Quality: Reduction of stratospheric ozone and increased penetration of UV-B radiation result in higher photo-dissociation rates of key trace gases that control the chemical reactivity of the troposphere. This can increase both production and destruction of ozone and related oxidants such as hydrogen peroxide, which are known to have adverse effects on human health, terrestrial plants and outdoor materials. Changes in the atmospheric concentrations of the hydroxyl radical (OH) may change the atmospheric lifetimes of important gases such as methane and substitutes of chlorofluorocarbons (CFCs). Increased tropospheric reactivity could also lead to increased production of particulates such as cloud condensation nuclei from the oxidation and subsequent nucleation of sulphur of both anthropogenic and natural origin (e.g. COS and DMS). Effects on Materials: Increased levels of solar UV radiation is known to have adverse effects on synthetic polymers, naturally occurring biopolymers and some other materials of commercial interest. UV-B radiation accelerates the photodegradation rates of these materials thus limiting their lifetimes. Typical damages range from discoloration to loss of mechanical integrity. Such a situation would eventually demand substitution of the affected materials by more photostable plastics and other materials in future. 2.7.2 Effects on Global Warming One of the strongest predictions of the greenhouse effect theory proponents is that the stratosphere will cool. The same CO2 radiative forcing that produces near-surface global warming is expected to cool the stratosphere. This cooling, in turn, is expected to produce a relative increase in ozone (O3) depletion and the frequency of ozone holes. Conversely, ozone depletion represents a “radiative forcing” of the climate system. There are two opposing effects: Reduced ozone causes the stratosphere to absorb less solar radiation, thus cooling the stratosphere while warming the troposphere; the resulting colder stratosphere emits less longwave radiation downward, thus cooling the troposphere. Overall, the cooling dominates; the IPCC concludes that “observed stratospheric O3 losses over the past two decades have caused a negative forcing of the surface-troposphere system” of about -0.15 ± 0.10 watts per square meter (W/m²)”. It is also said that although this cooling has been observed, it is not trivial to separate the effects of changes in the concentration of GHGs and ozone depletion since both will lead to cooling. Results from the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory show that above 20 km (12.4 miles), the GHGs dominate the cooling. Ozone depleting chemicals are also GHGs. The increases in concentrations of these chemicals have produced 0.34 ± 0.03 W/m² of radiative forcing, corresponding to about 14% of the total radiative forcing from increases in the concentrations of well-mixed greenhouse gases. The long-term modeling of the process, its measurement, study, design of theories and testing take decades to both document, gain wide acceptance, and


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ultimately become the dominant paradigm. Several theories about the destruction of ozone were hypothesized in the 1980s, published in the late 1990s, and are currently being proven. Dr Drew Schindell, and Dr Paul Newman, NASA Goddard, proposed a theory in the late 1990s, using a SGI Origin 2000 supercomputer, that modeled ozone destruction, accounted for 78% of the ozone destroyed. Further refinement of that model accounted for 89% of the ozone destroyed, but pushed back the estimated recovery of the ozone hole from 75 years to 150 years. An important part of that model is the lack of staratospheric flight due to depletion of fossil fuels. Ozone, while a minority constituent in the Earth’s atmosphere, is responsible for most of the absorption of UVB radiation. The amount of UVB radiation that penetrates through the ozone layer decreases exponentially with the slant-path thickness/density of the layer. Correspondingly, a decrease in atmospheric ozone is expected to give rise to significantly increased levels of UVB near the surface. Increases in surface UVB due to the ozone hole can be partially inferred by radiative transfer model calculations, but cannot be calculated from direct measurements because of the lack of reliable historical (pre-ozone-hole) surface UV data, although more recent surface UV observation measurement programmes exist. Because it is this same UV radiation that creates ozone in the ozone layer from O2 (regular oxygen) in the first place, a reduction in stratospheric ozone would actually tend to increase photochemical production of ozone at lower levels (in the troposphere), although the overall observed trends in total column ozone still show a decrease, largely because ozone produced lower down has a naturally shorter photochemical lifetime, so it is destroyed before the concentrations could reach a level which would compensate for the ozone reduction higher up. At this time, ozone at ground level is produced mainly by the action of UV radiation on combustion gases from vehicle exhausts, discussed in previous chapter. More often ozone depletion and global warming are interlinked in the mass media but in reality the connection between global warming and ozone depletion is not strong. The major component for stratospheric cooling the formation of circum-polar vortex more frequent at South Pole and less frequent at North Pole, which is corroborated with the observed ozone depletion patterns with latitude and season as well with South & North Poles as discussed above. Also, the downward long wave radiation from the stratospheric layer is insignificant in general. With all these arguments, yet it is pertinent to see that with the non-ozone depleting alternate substances introduction, the issue of stratospheric ozone is of not much significance but yet the alternate substances are still come under GHGs along with tropospheric ozone formation.


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Chapter 3

Solar Radiation 3.1

What is Solar Radiation?

Solar radiation is a general term for the electromagnetic radiation emitted by the Sun. It is radiant energy emitted by the Sun as a result of its nuclear fusion reactions. We can capture and convert solar radiation into useful forms of energy, such as heat and electricity, using a variety of technologies. The technical feasibility and economical operation of these technologies at a specific location depends on the available solar radiation. The spectrum of the Sun’s solar radiation (Figure 2a) is close to that of a black body with a temperature of about 5,800 0K [degrees absolute] » 6000 0K. The Sun emits radiation (energy) in different wavelengths/ bands, starting from X-rays (lower bandwidth side), g-rays, ultra-violet, visible, infrared (higher bandwidth side). The wavelength in which maximum energy is emitted depends upon the temperature of the emitting surface (the Sun, the Earth, or any other object). According to Plank’s Law the wavelength at which the maximum energy is emitted (λm) is given as: λm = a/T where ‘a’ is the constant given by 2830 and T is the emitting body’s surface temperature, given in degrees absolute (at zero degrees Celsius it is 273 degrees Absolute or Kelvin). The Sun’s surface temperature is around 6000 0C and the Earth’s surface temperature is around 10 0C. Thus the wavelength at which the maximum energy is located is given as: The Sun: (λm) = 2830/(6000 + 273) = 0.45 microns (mm) – short wave radiation; The Earth: (λm) = 2830/(10 + 273)

= 10.0 microns (mm) – long wave radiation;

Thus, the Sun emits maximum energy around 0.5μm wavelengths and the Earth emits at around 10μm wavelength. The former is known as short-wave radiation or visible radiation and later is known as long-wave radiation or infrared radiation. Solar Constant: The Solar constant is the amount of the Sun’s incoming electromagnetic radiation (Solar Radiation) per unit area, measured on the outer surface of the Earth’s Atmosphere – at the top of the atmosphere — in an aircraft perpendicular to the rays. The Solar constant includes all types of the solar radiation, not just the visible light. It is measured by satellite to be roughly 1,366 watts per square meter (W/m²), though this fluctuates by about 6.9% during a year (from 1,412 W/m² in early January to 1,321 W/m² in early July) due to the Earth’s varying distance from the Sun, and by a few parts per thousand from day to day. Thus, for the whole Earth (which has a cross section of 127,400,000 km2), the power is 1.740 x 1017 W, plus or minus 3.5%. Thus, the solar radiation reaching on an average on the top of the atmosphere is constant averaging about 1.96 ly/


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min [calories per minute per square centimeter, or Langley’s per minute]; this is equivalent to 1,366 W/m². Solar Radiation: The Earth receives a total amount of radiation determined by its cross section, but as it rotates this energy is distributed across the entire surface

area. Hence the average incoming Solar radiation (sometimes called the Solar irradiance), taking in to account the angle at which the rays strike and that at any one moment half the planet does not receive any solar radiation, is one-fourth the solar constant (approximately 342 W/m²). The amount of solar radiation actually reaching the atmosphere at any given place on the top of the atmosphere varies over the solar constant with the latitude and declination of the Sun and seasons. Thus, the amount of radiation received at


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the top of the free atmosphere at a given point (Ra, in ly/day) is given as (Fitz, 1949): Ra = 2.0 x (sin φ x sin δ + cos φ x cos δ x cosh) Where φ is the latitude of the place in degrees; δ is the declination of the Sun that varies with the seasons between 230 27’ N to 230 27’ S latitude (on March 23rd and September 22nd it is zero as the Sun is on equator and while on June 22nd and December 23rd at the two extremes]; and h is the hour angle of the Sun in degrees. Figure 3a presents the distribution of solar radiation received on the top of the free atmosphere (Ra) over different latitudes and seasons both in the Northern & Southern Hemispheres (estimated using the above equation). The values of January to December in Northern Hemisphere respectively refer to July to June values of Southern Hemisphere. 3.2

Types of Radiation

A typical Earth’s radiation budget is shown in Figure 3b. The incoming solar energy (Ra) is reflected by atmosphere around 6%, by clouds around 20%, by the Earth’s surface by around 4%; absorbed by atmosphere around 16%, by clouds by around 3%, by land and oceans by around 51%; radiated back to space by clouds and atmosphere is around 64%, radiation absorbed by atmosphere by around 15%, radiated directly to space from the Earth by around 6%; conduction and rising air by around 7%; carried to clouds and atmosphere by latent heat in water vapour by around 23%. However, all these vary with place and time and year. This gives only how the radiation budget is distributed in the Earth – Atmosphere system. This is divided into net short wave radiation and net long wave radiation. 3.2.1 Global Solar Radiation The amount of solar radiation actually reaching the Earth’s surface passing the atmosphere at any given place and time is quite different from the values seen in Figure 3a. Every location on the Earth receives sunlight at least part of the year. The amount of solar radiation that reaches any one “spot” on the Earth’s surface varies according to the Geographic location, Time of the day, Season, Local landscape, Local weather. Because the Earth is round, the Sun strikes the surface at different angles ranging from 0º (just above the horizon) to 90º (directly overhead). The day light hours at any given point on the Earth on a given day (N) is given as: N = (2/15) x cos-1 (- tan φ x tan δ) At the equator N is 12 hours in all the months (that is, day & night are equal) and from 660 27’ to poles it is 6 months day and 6 months night – in the Southern Hemisphere if it is night for 6 months, then the Northern Hemisphere presents 6 months day and vice-versa. In between these two conditions, N varies between 0 to 24 based on the season and location. The January to December in Northern Hemisphere respectively refer to July to June in the Southern Hemisphere.


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When the Sun’s rays are vertical, the Earth’s surface gets all the energy possible. The more slanted the Sun’s rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. Because the Earth is round, the frigid polar-regions never get a high sun, and because of the tilted axis of rotation, these areas receive no sun at all during part of the year. The Earth revolves around the Sun in an elliptical orbit and is closer to the Sun during part of the year. When the Sun is nearer the Earth, the Earth’s surface receives a little more solar energy. The Earth is nearer the Sun when it’s summer in the Southern Hemisphere and winter in the Northern Hemisphere. However the presence of vast oceans moderates the hotter summers and colder winters one would expect to see in the Southern Hemisphere as a result of these differences. 0

The 23.5 tilts in the Earth’s axis of rotation is a more significant factor in determining the amount of sunlight striking the Earth at a particular location. Thus, tilting results in longer days in the Northern Hemisphere from the spring (vernal) equinox to the fall (autumnal) equinox and longer days in the Southern Hemisphere during the other six months. The rotation of the Earth is responsible for hourly variations in sunlight. In the early morning and late afternoon, the Sun is low in the sky. Its rays travel further through the atmosphere than at noon when the Sun is at its highest point. On a clear day, the greatest amount of solar energy reaches a solar collector around solar noon. Thus, at any given moment, the amount of the solar radiation received at a location on the Earth’s surface depends on the state of the atmosphere/weather and the location’s latitude and season. In addition, the solar energy while passing through the atmosphere, some of it is partially depleted and attenuated as it traverses the atmospheric layers from the top of the atmosphere, preventing substantial portion of it from reaching the Earth’s surface. This phenomenon is due to absorption, scattering, and reflection in the atmosphere (Figure 3b). The solar radiation is reflected and scattered primarily by clouds (moisture & ice particles), particulate matter (dust, smoke, haze and smog), and various other gases. After modification some of this again reaches the Earth’s surface. This part is known as diffuse radiation. However, major part of the energy directly reaches the Earth’s surface. The direct plus the diffuse radiation that reaches the Earth’s surface is known as global solar radiation or total solar radiation or short wave radiation. Atmospheric condition reduces direct beam radiation by 10% on clear, dry days and by 100% during thick, cloudy days. 3.2.2 Net Radiation Balance The global solar radiation reaching the surface partly reflected back to the atmosphere and the ground absorbs the remaining part. The reflected part of radiation depends upon the albedo (ratio of reflected to incident radiation). The albedo varies with reflecting surface. That is the reflection depends on the nature of the surface and its cover and is approximately 5 to 7% for water and around 15 to 25% for most crops. This fraction varies with the degree of crop cover and wetness of the exposed soil surface. White bodies like snow reflects maximum and black bodies reflects minimum. That which remains is “net short wave radiation”. The Earth emits part of the absorbed radiation in long wave band known as infrared


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band. This also follows the same as albedo. That is white bodies emit less and black bodies emit more. That is, black bodies are efficient absorbers and as well efficient emitters. Some of the radiation leaving the Earth’s surface in long wave will be reached back through reflection and absorption/emission process. The difference between the out-going and in-coming long wave radiation is called “net long wave radiation”. The net balance of net short wave and net long wave is known as net radiation balance. If the net long wave radiation is more than the net short wave radiation then the net radiation is negative and vice versa case the net radiation is positive. This is recorded using net radiation balance meters. However, because of high costs, both global solar radiation and net radiation balance measuring instruments are located at few locations when compared to the measurements of other meteorological parameters. In view of this, these parameters are derived indirectly using other meteorological parameters (Reddy, 1987). The atmosphere absorbs long wave radiation more effectively than it does the short wave radiation emitted by the Sun. The absorption of this long wave radiation warms the atmosphere, transfer of sensible and latent heat also warms the atmosphere from the surface. The proponents of global warming, greenhouse gases [GHG] like water vapour, Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O) and Chlorofluorocarbons (CFCs) play an important role in the warming. It is argued that GHGs also emit long wave radiation both upward to space and downward to the surface. It is also argued that the downward part of this longwave radiation emitted by the atmosphere is the “greenhouse effect.” In fact the term “Greenhouse effect” is a misnomer, as this process is not the mechanism that warms greenhouses. The warming also depends upon the emitting surface and its’ surrounding conditions. The warming relates to the net long wave radiation. That is the balance between the out going and incoming long wave radiation at the Earth’s surface. Reports present absorption characteristics of major GHGs. The same reports also state that it is not possible to state that a certain gas causes a certain percentage of the greenhouse effect. That is, these are speculative values vary with atmospheric composition at any given point of time over a given place. That means this depends up on the state of atmosphere and relative interaction capacity. 3.3

Radiation

Climatology

Let us see the models to estimate global solar radiation & net radiation balance, to understand the localized influences on global solar radiation that is reaching Earth’s surface and net radiation balance at the Earth surface. Models: As the global solar radiation (Rt) and net radiation balance (Rn) measured at few selected locations, these are derived indirectly using other meteorological parameters using empirical formulae as they are part of major input in to several studies, more particularly in the estimation of evaporation & evapotranspiration. Reddy (1971a & b, 1981) & Reddy & Rao (1973) presented models to estimate Rt & Rn. They are given as follows:


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Rt = K [(1+0.8s) x (1-0.2t)/(0.1 x √h’) Rn= K (0.6+0.02Ts-0.04√h’)-h’ (4.3-√-T) K is the radiation constant at the surface of the observations in ly/day (cal/cm2/ day) K = (N/12) x (lN+ ϕij cos φ) x 102 l = 0.2/(1+0.1φ) – latitude factor; ϕij = seasonal factor (i = 1, 2, 3 in which 1, 2 and 3 stand for inland, coastal & hill stations, respectively, and j = 1, 2, — 12, in which 1 to 12 stand for January to December in the Northern Hemisphere and respectively refer to July to June in the Southern Hemisphere. These are given in Figure 3c. In the case of hill stations height correction factor is added as: K = K + 0.005H (12-N) in which H is the height of the place above mean sea level in meters; s = n/N where n is the mean hours of bright sunshine per day during a month & N is the mean length of the day in a given month. n is measured using Sunshine recorder or in the absence of measured data, this can be estimated using √ the model (Reddy, 1974) as follows: s = 1 – φ1 – f2; where φ1 = a x e-0.25 a and a = (Cl + Cm +Ch)/8 in which Cl, Cm & Ch respectively are the amounts of low, medium & high clouds, mean of 0830 & 1730 hours IST observations, in octas, varies between 0 and 1 as sky condition change from clear (zero octas) to overcast (8 octas) and e is the exponential function; and f2 = 0.02 + 0.08 cos 4φ upto 450 latitude and = –0.06 for latitudes beyond 450 latitude; t = r/M where r is the number of rainy days during the month and M is the number of days in the month; h’ is the mean relative humidity per day in the month. If h’ ≤ 36% then h’ = 35% only; T is the mean daily screen temperature during the month in oC. √-T is taken as -√T. Alternative Model-1: Where the abovepresented data sets are not available, alternate approach using the rainfall data, that is recoded at widely, is presented by Reddy, et al. (1984) for northeast Brazil. This is given as follows: Rt = a + b (φ) + c (P1/3); where φ is the latitude in degrees and P is the precipitation in mm & a, b & c are constants


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derived for northeast Brazil [in the Southern Hemisphere] are given below (Table 3): Table 3: Regression parameters vs Calendar months Months

a

b

c

N.H.

S.H.

January February March April May June July August September October November

July August September October November December January February March April May

444 501 523 517 543 510 532 608 685 551 477

- 2.00 - 1.00 0.70 4.70 10.66 10.59 15.17 8.50 3.70 0.50 - 1.50

-12.07 -13.20 -15.00 -20.20 -35.79 -30.07 -40.80 -44.44 -44.80 -23.70 -16.91

December

June

442

- 2.00

-14.00

N.H. = Northern Hemisphere; S.H. = Southern Hemisphere Alternative Model 2: To derive Rt and Rn for longer series to carryout power spectrum analysis Reddy, et al. (1977) presented: Rt = a x L x √ es & Rn = b x L x Tw and L = (1013.2/p)B x (N/12.5) and B = 1.5 x log φ; where a and b are constants (varying with seasons) given below (Table 4), es is the saturation vapour pressure in mb of mean surface temperature in absolute scale, Tw is the wet bulb temperature in 0C, L is the latitude and height correction factor, p is the station level pressure in mb. Table 4: Variation of “a” & “b” and “c” with seasons Month

a

b

c

January

90.0

8.50

11.4

February

97.0

9.50

11.8

March

93.0

9.75

12.8

April

85.0

10.63

13.0

May

77.0

9.75

12.2

June

65.0

8.50

11.5

July

60.0

8.75

10.0

August

63.0

9.37

10.0

September

70.0

9.37

10.6

October

74.0

9.00

11.4

November

80.8

8.13

11.4

December

85.0

7.50

11.4

Reddy (1976a) found a good relationship between the wet bulb temperatures (Tw, 0C ) and precipitable water (W, gm/cm2) by an equation W = c [Tw]2 in


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which c is given in Table 4. The total moisture content of the atmosphere is expressed as precipitable water vapour in the atmosphere. This is defined as the depth of liquid water that result by condensing all the vapour in a vertical column of the atmosphere over one square centimeter cross section. That mean Rn formula takes into account the moisture content in the vertical column of the atmosphere. Spatial Distribution: Reddy & Rao (1976) presented spatial distribution of Rt & Rn over India as estimated using models of Reddy (1971 a & b; 1981) & Reddy & Rao (1973). Figures 3d & e present spatial distribution of Rt & Rn over India, respectively for four representative months. Reddy (1976b) presented the spatial distribution of W over India that matches well with Rn data presented in Figure 3e. Reddy, et al., (1984) presented Rt distribution over northeast Brazil using their model (presented above). Figure 3f presents the spatial distribution of Rt for four representative months. The differences between theoretical and observed solar radiation at the top of the atmosphere and that actually reaching the ground by passing through the intervening atmosphere (Figure 3b) can be seen from Figure 3a and Figures3 d & f in space and time scales. They are quite different over different parts of the globe over different seasons. The above-presented equations clearly demonstrate that the moisture in the atmosphere plays the major role in both the short & long wave radiation balance at the Earth’s surface. However, the interactive effect varies with latitude & seasons on the one hand and land-sea-hill on the other.


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Chapter 4

Weather & Climate 4.1

What is Weather & Climate?

Weather: Weather is the mix of events that happen each day in our atmosphere including temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure. There are really a lot of other components to weather, namely sunshine, rain, cloud cover, winds, hail, snow, sleet, freezing rain, flooding, blizzards, ice storms, thunderstorms, steady rains from a cold front or warm front, excessive heat, heat waves, excessive cold, cold waves and more. Weather is basically the way the atmosphere is behaving, mainly with respect to its effects upon life and human activities. Weather is not the same everywhere. Perhaps it is hot, dry and sunny today where you live, but in other parts of the world it is cloudy, raining or even snowing. Everyday, weather events are recorded and predicted by meteorologists worldwide. In order to help people be prepared to face all of these, National Weather Services (NWS), in India we have “Indian Meteorological Department” (IMD), are the lead forecasting outlet for the nation’s weather. They also provide Special Weather Statements and Short and Long Term Forecasts. NWS also issues a lot of notices concerning marine weather for boaters and others who dwell or are staying near shorelines. Climate: Climate is the average weather pattern at a place. In most places, weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate, however, is the average of weather over time and space. An easy way to remember the difference is that climate is what you expect, like a very hot summer, and weather is what you get, like a hot day with pop-up thunderstorms. Meteorologists record the weather every day. The constant recording of weather information helps to determine the climate of an area. Climate is useful for weather forecasting. It also helps determine when the best time would be for farmers to plant their crops. It could even be helpful for you and your family to plan a vacation. In short, climate is the description of the long-term pattern of weather in a particular area. Some scientists define climate as the average weather for a particular region and time period, usually taken over 30-years. It’s really an average pattern of weather for a particular region. However, this gives wrong signal in areas with systematic variations in a given meteorological parameter. It is also true in areas where the ecological changes influencing the weather. The averages of weather taking into account these factors provide meaningful climate of the place. When scientists talk about climate, they’re looking at averages of precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hail storms, and other measures of the weather that occur over a long period in a particular place. For example, after looking at rain gauge data, lake and reservoir


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levels, and satellite data, scientists can tell if during a summer, an area was drier than average. If it continues to be drier than normal over the course of many summers, than it would likely indicate a change in the climate. The reason for studying climate and a changing climate is important in many ways as it will affect people around the world: The changing local & regional climates could alter forests, crop yields, and water supplies; & it could also affect human health, animals, and many types of ecosystems. Deserts may expand into existing rangelands, and features of some of our National Parks and National Forests may be permanently altered. Our weather is always changing and now scientists are discovering that our climate does not stay the same either. Climate, the average weather over a period of many years, differs in regions of the world that receive different amounts of sunlight and have different geographic factors, such as proximity to oceans, altitude, etc. 4.2

World Climates

Climate is the characteristic condition of the atmosphere near the Earth’s surface at a certain place on the Earth. It is the long-term weather of that area (at least 30 years). This includes the region’s general pattern of weather conditions, seasons and weather extremes like hurricanes, Typhoons, cyclones, droughts, floods, or rainy periods. Two of the most important factors determining an area’s climate are air temperature and precipitation. World biomes are controlled by climate. The climate of a region will determine what plants will grow there, and what animals will inhabit it. All three components, climate, plants and animals are interwoven to create the fabric of a biome. 4.2.1 Some Facts About Climate Geographical effect: The sun’s rays hit the equator at a direct angle between 23° 27’N and 23° 27’S latitude. Radiation that reaches the atmosphere here is at its most intense. In all other cases, the rays arrive at an angle to the surface and are less intense. The closer a place is to the poles, the smaller the angle and therefore the less intense the radiation. Our climate system is based on the location of these hot and cold air-mass regions and the atmospheric circulation created by trade winds and westerlies. Trade winds North of the equator blow from the Northeast. South of the equator, they blow from the Southeast. The trade winds of the two hemispheres meet near the equator, causing the air to rise. As the rising air-cools, clouds and rain develop. The resulting bands of cloudy and rainy weather near the equator create tropical conditions. Westerlies blow from the Southwest on the Northern Hemisphere and from the Northwest in the Southern Hemisphere. Westerlies steer storms from West to East across middle latitudes. Both westerlies and trade winds blow away from the 30° latitude belt. Over large areas centered at 30° latitude, surface winds are light. Air slowly descends to replace the air that blows away. Any moisture the air contains evaporates in the intense heat. The tropical deserts, such as the Sahara of Africa, Thar in India and the Sonoran of Mexico, exist under these regions.


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Seasons: The Earth rotates about its axis, which is tilted at 23.5 degrees. This tilt and the Sun’s radiation result in the Earth’s seasons. The Sun emits rays that hit the Earth’s surface at different angles. These rays transmit the highest level of energy when they strike the Earth at a right angle (90 °). Temperatures in these areas tend to be the hottest places on the Earth. Other locations, where the Sun’s rays hit at lesser angles, tend to be cooler. As the Earth rotates on it’s tilted axis around the Sun, different parts of the Earth receive higher and lower levels of radiant energy . This creates the seasons. 4.2.2 Types of Climates Classification of Climates: The purpose of climatic classification is to identify those aspects of climate, which distinguish a region from nearby regions and to draw inferences on the influence of climatic factors on human, animal and plant life. In an environmental context this may allow areas to be characterized and boundaries to be drawn around contiguous areas that can be regarded as homogeneous in certain respects. Under given climatic conditions there are similarities in natural vegetation, soils, crop probabilities, etc. Broad areas exit with climatic homogeneity, which allows a simple classification to be an aid to study and understand the Earth’s land and people. Reddy (1983a & b) presented reviews of climatic classification procedures. For the present purpose selected the Koppen’s classification procedure (Koppen, 1936) as it is the most widely used “generalized climatic classification system of the world”. Köppen Climate Classification System: In the Koppen classification system the Earth’s surface is divided into climatic regions that generally coincided with world patterns of vegetation and soils [Figure 4a]. The system recognizes five major climate types based on the annual and monthly averages of temperature and precipitation. Each type is designated by a capital letter. A - Moist Tropical Climates are known for their high temperatures year round and for their large amount of year round rain; B - little rain and a huge daily temperature range characterize Dry Climates. Two subgroups, S - semiarid or steppe, and W - arid or desert, are used with the B climates; C - In Humid Middle Latitude Climates land/water differences play a large part. These climates have warm, dry summers and cool, wet winters; D - Continental Climates can be found in the interior regions of large landmasses. Total precipitation is not very high and seasonal temperatures vary widely; E - Cold Climates are part of areas where permanent ice and tundra are always present. Only about four months of the year have above freezing temperatures; A second, lower case letter designates further subgroups that distinguish specific seasonal characteristics of temperature and precipitation; f - Moist with adequate precipitation in all months and no dry season. This letter usually accompanies the A, C, and D climates;


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m - Rainforest climate in spite of short, dry season in monsoon type cycle. This letter only applies to A climates; s - Dry season in the summer of the respective hemisphere (high-sun season); w - Dry season in the winter of the respective hemisphere (low-sun season); To further denote variations in climate, a third letter was added to the code. a - Hot summers where the warmest month is over 22°C (72°F). These can be found in C and D climates; b - Warm summer with the warmest month below 22°C (72°F). These can also be found in C and D climates; c - Cool, short summers with less than four months over 10°C (50°F) in the C and D climates; d - Very cold winters with the coldest month below -38°C (-36°F) in the D climate only; h - Dry-hot with a mean annual temperature over 18°C (64°F) in B climates only; k - Dry-cold with a mean annual temperature under 18°C (64°F) in B climates only. Three basic climate groups: Three major climate groups show the dominance of special combinations of air-mass source regions. Group1: Low Latitude Climates These climates are controlled by equatorial tropical air masses. Tropical Moist Climates (Af) — Rainforests: Rainfall is heavy in all months. The total annual rainfall is often more than 250 cm (100 in). There are seasonal differences in monthly rainfall but temperatures of 27°C (80°F) mostly stay the same. Humidity is between 77 and 88%. High surface heat and humidity cause cumulus clouds to form early in the afternoons almost every day. The climates on the eastern sides of continents are influenced by maritime tropical air masses. These air masses flow out from the moist western sides of oceanic high-pressure cells, and bring lots of summer rainfall. The summers are warm and very humid. It also rains a lot in the winter: Average temperature: 18 °C (°F); Annual Precipitation: 262 cm (103 in); Latitude Range: 10° S to 25 ° N; Global Position: Amazon Basin, Congo Basin of equatorial Africa, East Indies, from Sumatra to New Guinea. Wet-Dry Tropical Climates (Aw) — Savanna: A seasonal change occurs between wet tropical air masses and dry tropical air masses. As a result, there is a very wet season and a very dry season. Trade winds dominate during the dry season. It gets a little cooler during this dry season but will become very hot just before the wet season: Temperature Range: 16 °C; annual Precipitation: 0.25 cm (0.1 in). All months less than 0.25 cm (0.1 in); Latitude Range: 15 ° to 25 ° N and S; Global Range: India, Indochina, West Africa, southern Africa, South America and the north coast of Australia


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Dry Tropical Climate (BW) — Desert biome: These desert climates are found in low-latitude deserts approximately between 18° to 28° in both hemispheres. These latitude belts are centered on the tropics of Cancer and Capricorn, which lie just north and south of the equator. They coincide with the edge of the equatorial subtropical high-pressure belt and trade winds. Winds are light, which allows for the evaporation of moisture in the intense heat. They generally flow downward so the area is seldom penetrated by air masses that produce rain. This makes for a very dry heat. The dry arid desert is a true desert climate, and covers 12 % of the Earth’s land surface: Temperature Range: 16° C; Annual Precipitation: 0.25 cm (0.1 in) with all months less than 0.25 cm (0.1 in); Latitude Range: 15° - 25° N and S; Global Range: southwestern United States and northern Mexico, Argentina, north Africa, south Africa, central part of Australia. Group 2: Mid Latitude Climates Climates in this zone are affected by two different air masses. The tropical air masses are moving towards the poles and the polar air masses are moving towards the equator. These two air masses are in constant conflict. Either air mass may dominate the area, but neither has exclusive control. Dry Mid-latitude Climates (BS) — Steppe: Characterized by grasslands, this is a semiarid climate. It can be found between the desert climate (BW) and more humid climates of the A, C, and D groups. If it received less rain, the steppe would be classified as an arid desert. With more rain, it would be classified as a tall grass prairie. This dry climate exists in the interior regions of the North American and Eurasian continents. Moist ocean air masses are blocked by mountain ranges to the west and south. These mountain ranges also trap polar air in winter, making winters very cold. Summers are warm to hot: Temperature Range: 24° C (43° F); Annual Precipitation: less than 10 cm (4 in) in the driest regions to 50 cm (20 in) in the moister steppes; Latitude Range: 35° - 55° N; Global Range: Western North America (Great Basin, Columbia Plateau, Great Plains), Eurasian interior, from steppes of eastern Europe to the Gobi Desert and North China. Mediterranean Climate (Cs) — Chaparral biome: This is a wet-winter, dry-summer climate. Extremely dry summers are caused by the sinking air of the subtropical highs and may last for up to five months. Plants have adapted to the extreme difference in rainfall and temperature between the Winter and the Summer seasons. Clerophyll plants range in formations from forests, to woodland, and scrub. Eucalyptus forests cover most of the chaparral biome in Australia. Fires occur frequently in Mediterranean climate zones: Temperature Range: 7 °C (12 °F); Annual Precipitation: 42 cm (17 in); Latitude Range: 30° - 50° N and S; Global Position: central and southern California, coastal zones bordering the Mediterranean Sea, coastal Western Australia and South Australia, Chilean coast, Cape Town region of South Africa.


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Dry Mid-latitude Climates (Bs) — Grasslands biome: These dry climates are limited to the interiors of North America and Eurasia. Ocean air masses are blocked by mountain ranges to the west and south. This allows polar air masses to dominate in winter months. In the summer, a local continental air mass is dominant. A small amount of rain falls during this season. Annual temperatures range widely. Summers are warm to hot, but winters are cold Temperature Range: 31 °C (56°F); Annual Precipitation: 81 cm (32 in); Latitude Range: 30° - 55° N and S; Global Position: western North America (Great Basin, Columbia Plateau, Great Plains), Eurasian interior. Moist Continental Climate (Cf) — Deciduous Forest biome: This climate is in the polar front zone - the battleground of polar and tropical air masses. Seasonal changes between summer and winter are very large. Daily temperatures also change often. Abundant precipitation falls throughout the year. It is increased in the summer season by invading tropical air masses. Cold winters are caused by polar and arctic masses moving south: Temperature Range: 31 °C (56 ° F); Average Annual Precipitation: 81 cm (32 in); Latitude Range: 30° - 55° N and S (Europe: 45° - 60° N); Global Position: eastern parts of the United States and southern Canada, northern China, Korea, Japan, central and Eastern Europe. Group 3: High Latitude Climates Polar and arctic air masses dominate these regions. Canada and Siberia are two air-mass sources, which fall into this group. A southern hemisphere counterpart to these continental centers does not exist. Air masses of arctic origin meet polar continental air masses along the 60th and 70th parallels. Boreal forest Climate (Dfc) — Taiga biome: This is a continental climate with long, very cold winters, and short, cool summers. This climate is found in the polar air mass region. Very cold air masses from the arctic often move in. The temperature range is larger than any other climate. Precipitation increases during summer months, although annual precipitation is still small. Much of the boreal forest climate is considered humid. However, large areas in western Canada and Siberia receive very little precipitation and fall into the sub-humid or semi-arid climate type. Temperature Range: 41 °C (74 °F), lows; -25 °C (-14 °F), highs; 16 °C (60 °F); Average Annual Precipitation: 31 cm (12 in); Latitude Range: 50° - 70° N and S; Global Position: central and western Alaska, Canada, from the Yukon Territory to Labrador, Eurasia, from northern Europe across all of Siberia to the Pacific Ocean. Tundra Climate (E) — Tundra biome: The tundra climate is found along arctic coastal areas. Polar and arctic air masses dominate the tundra climate. The winter season is long and severe. A short, mild season exists, but not a true summer season. Moderating ocean winds keep the temperatures from being as severe as interior regions: Temperature Range: -22 °C to 6 °C (-10 °F to 41 °F); Average Annual Precipitation: 20 cm (8 in); Latitude Range: 60° - 75° N; Global Position: arctic zone of North America, Hudson Bay region, Greenland coast; northern Siberia bordering the Arctic Ocean.


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Highland Climate (H) — Alpine biome: Highland climates are cool to cold, found in mountains and high plateaus. Climates change rapidly on mountains, becoming colder the higher the altitude gets. The climate of a highland area is closely related to the climate of the surrounding biome. The highlands have the same seasons and wet and dry periods as the biome they are in. Mountain climates are very important to mid-latitude biomes. They work as water storage areas. Snow is kept back until spring and summer when it is released slowly as water through melting. Temperature Range: -18 °C to 10 °C (-2 °F to 50°F); Average Annual Precipitation: 23 cm (9 in); Latitude Range: found all over the world; Global Position: Rocky Mountain Range in North America, the Andean mountain range in South America, the Alps in Europe, Mt. Kilimanjaro in Africa, the Himalayans in India, Mt. Fuji in Japan. 4.2.3 Cyclone Disturbances The terms “hurricane” and “typhoon” are regionally specific names for a strong “tropical cyclone”. A tropical cyclone is the generic term for a non-frontal synoptic scale low-pressure system over tropical or sub-tropical waters with organized convection (i.e. thunderstorm activity) and definite cyclonic surface wind circulation. Figure 4b presents the primary storm tracks. Tropical cyclones with maximum sustained surface winds of less than 17 m/s (34 kt, 39 mph) are called “Tropical Depressions”. Once the tropical cyclone reaches winds of at least 17 m/s (34 kt, 39 mph) they are typically called a “tropical storm” and assigned a name. If winds reach 33 m/s (64 kt, 74 mph)), then they are called “hurricane” (the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E) or “typhoon” (the Northwest Pacific Ocean west of the dateline) or “severe tropical cyclone” (the Southwest Pacific Ocean west of 160 0E or Southeast Indian Ocean east of 90 0E) or “severe cyclonic storm” (the North Indian Ocean) or “tropical cyclone” (the Southwest Indian Ocean). “Super-typhoon” is a term utilized by the U.S. Joint Typhoon Warning Center for typhoons that reach maximum sustained 1-minute surface winds of at least 65 m/s (130 kt, 150 mph). This is the equivalent of a strong category 4 or 5 hurricane in the Atlantic basin or a category severe tropical cyclone in the Australian basin. “Major hurricane” is a term utilized by the U.S. National Hurricane Center for hurricanes that reach maximum sustained 1-minute surface winds of at least 50 m/s (96 kt, 111 mph). This is the equivalent of category 3, 4 & 5. “Intense hurricane” is an unofficial term, but is often used in the scientific literature. It is the same as “major hurricane”. It has been recognized since at least the 1930s that lower tropospheric (from the Ocean surface to about 5 km [3 mi] with a maximum at 3 km [2 mi]) westward traveling disturbances often serve as the “seedling” circulations for a large proportion of tropical cyclones over the North Atlantic Ocean. These disturbances, now known as African easterly waves, had their origins over North Africa. The jet arises as a result of the reversed lower-tropospheric temperature gradient over western and central North Africa due to extremely warm temperatures


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over the Saharan Desert in contrast with substantially cooler temperatures along the Gulf of Guinea coast. The waves move generally toward the west in the lower tropospheric trade wind flow across the Atlantic Ocean. They are first seen usually in April or May and continue until October or November. The waves have a period of about 3 or 4 days and a wavelength of 2000 to 2500 km [1200 to 1500 mi], typically. One should keep in mind that the “waves” can be more correctly thought of as the convectively active troughs along an extended wave train. On average, about 60 waves are generated over North Africa each year, but it appears that the number that is formed has no relationship to how much tropical cyclone activity there is over the Atlantic each year. While only about 60% of the Atlantic tropical storms and minor hurricanes category 1 & 2 originate from easterly waves, nearly 85% of the intense (or major) hurricanes have their origins as easterly waves. It is suggested, though, that nearly all of the tropical cyclones that occur in the Eastern Pacific Ocean can also be traced back to Africa. A tropical cyclone is a discrete tropical weather system of apparently organized convection - generally 200 to 600 km (100 to 300 nmi) in diameter originating in the tropics or subtropics, having a non-frontal migratory character, and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field. Disturbances associated with perturbations in the wind field and progressing through the tropics from east to west are also known as easterly waves. Tropical Depression: A tropical cyclone in which the maximum sustained wind speed is 33 kt (38 mph, 17 m/s). Depressions have a closed circulation. Tropical Storm: A tropical cyclone in which the maximum sustained wind speed ranges from 34 kt (39 mph, 17.5 m/s) to 63 kt (73 mph, 32.5 m/s). The convection in tropical storms is usually more concentrated near the center with outer rainfall organizing into distinct bands. Hurricane: When winds in a tropical cyclone equal or exceed 64 kt (74 mph, 33 m/ s) it is called a hurricane (in the Atlantic and eastern and central Pacific Oceans). Hurricanes are further designated by categories. Hurricanes in categories 3, 4, 5 are known as Major Hurricanes or Intense Hurricanes. The wind speed mentioned here are for those measured or estimated as the top speed sustained for one minute at 10 meters above the surface. Peak gusts would be on the order of 1025% higher. A sub-tropical cyclone: A sub-tropical cyclone is a low-pressure system existing in the tropical or subtropical latitudes (anywhere from the equator to about 50°N) that has characteristics of both tropical cyclones and mid-latitude (or extra-tropical) cyclones. Therefore, many of these cyclones exist in a weak to moderate horizontal temperature gradient region (like mid-latitude cyclones), but also receive much of their energy from convective clouds (like tropical cyclones). Often, these storms have a radius of maximum winds, which is farther out (on the order of 100-200 km


57


[60-125 miles] from the center) than what is observed for purely “tropical” systems. Additionally, the maximum sustained wind for sub-tropical cyclones have not been observed to be stronger than about 33 m/s (64 kts, 74 mph)). Many times these subtropical storms transform into true tropical cyclones. A recent example is the Atlantic basin’s Hurricane Florence in November 1994, which began as a subtropical cyclone before becoming fully tropical. Note there has been at least one occurrence of tropical cyclones transforming into a subtropical storm (e.g. Atlantic basin storm 8 in 1973). Subtropical cyclones in the Atlantic basin are classified by the maximum sustained surface winds: less than 18 m/s (34 kts, 39 mph) - “subtropical depression”, greater than or equal to 18 m/s (34 kts, 39 mph) - “subtropical storm”. Prior to 2002 subtropical storms were not given names, but issued forecasts and warnings similar to those for tropical cyclones. Now they are given names from the tropical cyclone list. Extra-tropical Cyclones: An extra-tropical cyclone is a storm system that primarily gets its energy from the horizontal temperature contrasts that exist in the atmosphere. Extra-tropical cyclones (also known as mid-latitude or baroclinic storms) are low-pressure systems with associated cold fronts, warm fronts, and occluded fronts. Tropical cyclones, in contrast, typically have little to no temperature differences across the storm at the surface and their winds are derived from the release of energy due to cloud/rain formation from the warm moist air of the tropics. Structurally, tropical cyclones have their strongest winds near the Earth’s surface, while extra-tropical cyclones have their strongest winds near the tropopause. These differences are due to the tropical cyclone being “warm-core” in the troposphere (below the tropopause) and the extra-tropical cyclone being “warmcore” in the stratosphere (above the tropopause) and “cold-core” in the troposphere. “Warm-core” refers to being relatively warmer than the environment at the same pressure surface (“pressure surfaces” are simply another way to measure height or altitude). Often, a tropical cyclone will transform into an extra-tropical cyclone as it re-curves pole ward and to the East. Occasionally, an extra-tropical cyclone will lose its frontal features, develop convection near the center of the storm and transform into a full-fledged tropical cyclone. Such a process is most common in the North Atlantic and Northwest Pacific basins. The transformation of tropical cyclone into an extra-tropical cyclone (and vice versa) is currently one of the most challenging forecast problems. The rule used to be that if the tropical storm or hurricane moved into a different basin, then it was renamed to whatever name was next on the list for the area. The last time that this occurred was in July 1996 when Atlantic basin Tropical Storm Cesar moved across Central America and was renamed Northeast Pacific basin Tropical Storm Douglas. The last time that a Northeast Pacific system moved into the Atlantic basin was in June 1989 when Cosme became Allison. However, these rules have now changed at the National Hurricane Center and if the system remains a tropical cyclone as it moves across Central America, then it will keep the


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original name. Only if the tropical cyclone dissipates with just a tropical disturbance remaining, will give the system a new name assuming it becomes a tropical cyclone once again in its new basin. The reason is that the Earth’s rotation sets up an apparent force (called the Coriolis force) that pulls the winds to the right in the Northern Hemisphere (and to the left in the Southern Hemisphere). So when a low pressure starts to form North of the equator, the surface winds will flow inward trying to fill in the low and will be deflected to the right and a counter-clockwise rotation will be initiated. The opposite (a deflection to the left and a clockwise rotation) will occur South of the equator. The Atlantic hurricane season is officially from 1 June to 30 November. There is nothing magical in these dates, and hurricanes have occurred outside of these six months, but these dates were selected to encompass over 97% of tropical activity. June 1st has been the traditional start of the Atlantic hurricane season for decades. However, the end date has been slowly shifted outward, from October 31st to November 15th until its current date of November 30th. The Atlantic basin shows a very peaked season from August through October, with 78% of the tropical storm days, 87% of the minor (Saffir-Simpson Scale categories 1 and 2 hurricane days, and 96% of the major (Saffir-Simpson Scale categories 3, 4 and 5) hurricane days occurring then). Maximum activity is in early to mid September. Once in a few years there may be a tropical cyclone occurring “out of season” primarily in May or December. The Northeast Pacific basin has a broader peak with activity beginning in late May or early June and going until late October or early November with a peak in storminess in late August/early September. NHC’s official dates for this basin are from May 15th to November 30th. The Northwest Pacific basin has tropical cyclones occurring all year round regularly. There is no official definition of typhoon season for this reason. There is a distinct minimum in February and the first half of March, and the main season goes from July to November with a peak in late August/early September. The North Indian basin has a double peak of activity in May and November though tropical cyclones are seen from April to December. The severe cyclonic storms (>33 m/s winds [76 mph]) occur almost exclusively from April to June and late September to early December. The Southwest Indian and Australian/Southeast Indian basins have very similar annual cycles with tropical cyclones beginning in late October/early November, reaching a double peak in activity - one in mid-January and one in mid-February to early March, and then ending in May. The Australian/Southeast Indian basin February lull in activity is a bit more pronounced than the Southwest Indian basin’s lull. The Australian/Southwest Pacific basin begin with tropical cyclone activity in late October/early November, reaches a single peak in late February/early March, and then fades out in early May. Globally, September is the most active month and


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May is the least active month. El Niño/Southern Oscillation (ENSO) - During El Niño events (ENSO warm phase), tropospheric vertical shear is increased inhibiting tropical cyclone genesis and intensification, primarily by causing the 200 mb (12 km or 8 mi) westerly winds to be stronger. La Nina events (ENSO cold phase) enhance activity. The changes to the moist static stability can also contribute toward hurricane changes due to ENSO, with a drier, more stable environment present during El Nino events. The Australian/Southwest Pacific shows a pronounced shift back and forth of tropical cyclone activity with fewer tropical cyclones between 145° and 165°E and more from 165°E eastward across the South Pacific during El Niño (warm ENSO) events. There is also a smaller tendency to have the tropical cyclones originate a bit closer to the equator. The opposite would be true in La Niña (cold ENSO) events. The western portion of the Northeast Pacific basin (140°W to the dateline) has been suggested to experience more tropical cyclone genesis during the El Niño year and more tropical cyclones tracking into the sub-region in the year following an El Niño, but this has not been completely documented yet. The Northwest Pacific basin, similar to the Australian/Southwest Pacific basin, experiences a change in location of tropical cyclones without a total change in frequency. West of 160°E observed reduced numbers of tropical cyclone genesis with increased formations from 160E to the dateline during El Niño events. The opposite occurred during La Niña events. Again there is also the tendency for the tropical cyclones to also form closer to the equator during El Niño events than average. The eastern portion of the Northeast Pacific, the Southwest Indian, the Southeast Indian/Australian, and the North Indian basins have either shown little or a conflicting ENSO relationship and/or have not been looked at yet in sufficient detail. Tornadoes: While both tropical cyclones and tornadoes are atmospheric vortices, they have little in common. Tornadoes have diameters on the scale of 100s of meters and are produced from a single convective storm (i.e. a thunderstorm or cumulonimbus). A tropical cyclone, however, has a diameter on the scale of 100s of kilometers and is comprised of several to dozens of convective storms. Additionally, while tornadoes require substantial vertical shear of the horizontal winds (i.e. change of wind speed and/or direction with height) to provide ideal conditions for tornado genesis, tropical cyclones require very low values (less than 10 m/s [20 kt, 23 mph]) of tropospheric vertical shear in order to form and grow. These vertical shear values are indicative of the horizontal temperature fields for each phenomenon: tornadoes are produced in regions of large temperature gradient, while tropical cyclones are generated in regions of near zero horizontal temperature gradient. Tornadoes are primarily over-land phenomena as solar heating of the land surface usually contributes toward the development of the thunderstorm that spawns the vortex (though over-water tornadoes have occurred). In contrast, tropical cyclones


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are purely oceanic phenomena - they die out over-land due to a loss of a moisture source. Lastly, tropical cyclones have a lifetime that is measured in days, while tornadoes typically last on the scale of minutes. An interesting side note is that tropical cyclones at landfall often provide the conditions necessary for tornado formation. As the tropical cyclone makes landfall and begins decaying, the winds at the surface die off quicker than the winds at, say, 850 mb. This sets up a fairly strong vertical wind shear that allows for the development of tornadoes, especially on the tropical cyclone’s right side (with respect to the forward motion of the tropical cyclone). For the southern hemisphere, this would be a concern on the tropical cyclone’s left side - due to the reverse spin of southern hemisphere storms. 4.2.4 Monsoons Indian Monsoons: Book of Das (1968) presents the monsoons in India. At the Equator, the area near India is unique in that dominant or frequent westerly winds occur at the surface almost constantly throughout the year; the surface easterlies reach only to 20º N in February, and even then they have a very strong northerly component. They soon retreat northward, and drastic changes take place in the upper-air circulation. This is a time of transition between the end of one monsoon and the beginning of the next. Late in March the high-sun season reaches the Equator and moves farther north. With it go atmospheric instability, convectional (rising, turbulent) clouds, and rain. The westerly subtropical jet stream still controls the flow of air across northern India and the surface winds are north-easterlies. As the high-sun season moves northward during April, India becomes particularly prone to rapid heating because the highlands to the north protect it from any incursions of cold air. In May the southwesterly monsoon is well established over Sri Lanka. There are three distinct regions of relative upper tropospheric warmth— namely (1) above the southern Bay of Bengal, (2) above the highlands of Tibet, and (3) across the still, dry trunks of the peninsulas. The relatively warm area above the southern Bay of Bengal occurs mostly at the 500-100 mb level. It does not appear at a lower level and is probably caused by the release of condensation heat (associated with the change from water vapour to liquid water) at the top of towering cumulonimbus clouds along the advancing inter-tropical convergence. In May the dry surface of Tibet (above 4,000 m) absorbs and radiates heat that is readily transmitted to the air immediately above. At about 6,000 m an anticyclonic cell arises, causing a strong easterly flow in the upper troposphere above northern India. The subtropical jet stream suddenly changes its course to the North of the anti-cyclonic ridge and the highlands, though it may occasionally reappear southward of them for very brief periods. This change of the upper tropospheric circulation above northern India from westerly jet to easterly flow coincides with a reversal of the vertical temperature and pressure gradients between 600 and 300 mb. On many occasions the easterly aloft assumes jet force. It anticipates by a few days the “burst,” or onset, of the surface southwesterly monsoon some 1,500 km farther south, with a definite sequential relationship,


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although the exact cause is not known. Because of India’s inverted triangular shape, the land is heated progressively as the Sun moves northward. This accelerated spread of heating, combined with the general direction of heat being transported by winds, results in a greater initial monsoon activity over the Arabian Sea (at late spring time), where a real frontal situation often occurs, than over the Bay of Bengal. The relative humidity of coastal districts in the Indian region rises above 70% and some rain occurs. Above the heated land the air below 1,500 m becomes unstable, but it is held down by the overriding easterly flow. This does not prevent frequent thunderstorms in late May. During June the easterly jet becomes firmly established at 150 to 100 mb. It reaches its greatest speed at its normal position to the South of the anti-cyclonic ridge, at about 15º N from China through India. In Arabia, it decelerates and descends to the middle troposphere (3,000 m). A stratospheric belt of very cold air, analogous to the one normally found above the ITCZ near the Equator, occurs above the anti-cyclonic ridge, across southern Asia at 30º-40º N and above the 6,000-m (500 mb) level. These upper air features that arise so far away from the Equator are associated with the surface monsoon and are absent when there is no monsoon flow. The position of the easterly jet controls the location of monsoon rains, which occur ahead and to the left of the strongest winds and behind them to the right. The surface flow, however, is a strong, southwesterly, humid, and unstable wind that brings humidities of more than 80% and heavy, squally showers that are the “burst” of the monsoon. The overall pattern of the advance follows a frontal alignment, but local episodes may differ considerably. The amount of rain is variable from year to year and place to place. Most spectacular clouds and rain occur against the Western Ghats, where the early monsoon air-stream piles up against the steep slopes, then recedes, and piles up again to a greater height. Each time it pushes thicker clouds upward until wind and clouds roll over the barrier and, after a few brief spells of absorption by the dry inland air, cascade toward the interior. The windward slopes receive from 2,000 to 5,000 mm of rain in the monsoon season. Various factors, and especially topography, combine to make up a complex regional pattern. Oceanic air flowing toward India below 6,000 m is deflected in accordance with the Coriolis effect. The converging, moist oncoming stream becomes unstable over the hot land and is subject to convectional turmoil. Towering cumulonimbus clouds rise thousands of m, producing violent thunderstorms and releasing latent heat in the surrounding air. As a result, the upper tropospheric warm belt migrates northwestward from the ocean to the land. The main body of air above 9,000 m maintains a strong easterly flow. Later, in June and July, the monsoon is strong and well established to a height of 6,000 m (less in the far North); with occasional thickening to 9,000 m. Weather conditions are cloudy, warm, and moist all over India. Rainfall varies between 400 and 500 mm, but topography introduces some extraordinary differences. On the southern slopes of the Khasi Hills at only 1,300 m, where the moist airstreams are lifted and overturned, Cherrapunji has an average rainfall of 2,730 mm in July,


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with record totals of 897 mm in 24 hours in July 1915, more than 9,000 mm in July 1861, and 16,305 mm in the monsoon season of 1899. Over the Ganges Valley the monsoon, deflected by the Himalayan barrier, becomes a southeasterly air-flow. By then the upper tropospheric belt of warmth from condensation has moved above northern India, with an oblique bias. The lowest pressures prevail at the surface. It is mainly in July and August that waves of low pressure appear in the body of monsoon air. Fully developed depressions appear once or twice a month. They travel from east to west more or less concurrently with high-level easterly waves and bursts of speed in the easterly jet, causing local strengthening of the low-level monsoon flow. The rainfall consequently increases and is much more evenly distributed than it was in June. Some of the deeper depressions become tropical cyclones before they reach the land, and these bring torrential rains and disastrous floods. A totally different development arises when the easterly jet moves farther north than usual because the monsoon wind rising over the southern slopes of the Himalayas brings heavy rains and local floods. The weather over the central and southern districts, however, becomes suddenly drier and remains so for as long as the abnormal shift lasts. The opposite shift is also possible, with mid-latitude upper air flowing along the south face of the Himalayas and bringing drought to the northern districts. Such dry spells are known as “breaks” of the monsoon. Those affecting the south are similar to those experienced on the Guinea coast during extreme northward shifts of the wind belts (as later discussed), whereas those affecting the north are due to an interaction of the middle and lower latitudes. The southwest monsoon over the lower Indus Plain is only 500 m thick and does not hold enough moisture to bring rain. On the other hand, the upper tropospheric easterlies become stronger and constitute a true easterly jet stream. Western Pakistan, Iran, and Arabia remain dry (probably because of divergence in this jet) and thus become the new source of surface heat. By August the intensity and duration of sunshine have decreased, temperatures begin to fall, and the surge of southwesterly air diminishes spasmodically almost to a standstill in the northwest. Cherrapunji still receives over 2,000 mm of rainfall at this time, however. In September dry, cool, northerly air begins to circle the west side of the highlands and spread over northwestern India. The easterly jet weakens and the upper tropospheric easterlies move much farther south. Because the moist south-westerlies at lower levels are much weaker and variable, they are soon pushed back. The rainfall becomes extremely variable over most of the region, but showers are still frequent in the southeastern areas and over the Bay of Bengal. By early October variable winds are very frequent everywhere. At the end of the month the entire Indian region is covered by northerly air and the winter monsoon takes shape. The surface flow is deflected by the Coriolis force and becomes a northeasterly flow. This causes an October-December rainy season for


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the extreme southeast of the Deccan (including the Tamil Nadu coast) and eastern Sri Lanka, which cannot be explained by topography alone because it extends well out over the sea. Tropical depressions and cyclones are important contributing factors. Most of India thus begins a sunny, dry, and dusty season. The driest period comes in November in the Punjab; December in Central India, Bengal, and Assam; January in the northern Deccan; and February in the southern Deccan. Conversely, the western slopes of the Karakoram and Himalayas are then reached by the midlatitude frontal depressions that come from the Atlantic and the Mediterranean. The winter rains they receive, moderate as they are, place them clearly outside the monsoon realm. Because crops and water supplies depend entirely on monsoon rains, it became imperative that quantitative, long-range weather forecasts be available. For a forecast to be released at the beginning of June, it is necessary to use, in April, South American pressure data and Indian upper-wind conditions (positive correlation) and, in May, rainfall in Zimbabwe and Java and easterly winds above Calcutta (negative correlation). The Malaysian-Australian Monsoon: Southeast Asia and northern Australia are combined in one monsoon system that differs from others because of the peculiar and somewhat symmetrical distribution of landmasses on both sides of the Equator. In this respect, the northwest monsoon of Australia is unique. The substantial masses of water between Asia and Australia have a moderating effect on tropospheric temperatures, weakening the summer monsoon. The many islands (e.g., Philippines and Indonesia) provide an infinite variety of topographic effects. Typhoons that develop within the monsoon air bring additional complications. It would be possible to exclude North China, Korea, and Japan from the monsoon domain because their seasonal rhythm follows the normal mid-latitude pattern—a predominant outflow of cold continental air in winter, and frontal depressions and rain alternating with fine, dry anti-cyclonic weather in the warm season. On the other hand, the seasonal reversal of wind direction in this area is almost as persistent as that in India. The winter winds are much stronger because of the relative proximity of the Siberian anticyclone. The tropical ridge of high pressure is the natural boundary between these non-monsoonal areas and the monsoon lands farther south. The northern limit of the typical monsoon may be set at about latitude 25º N. Farther North, the summer monsoon is not strong enough to overcome the effect of the traveling anticyclones normally typical of the subtropics. As a result, monsoon rains occur in June and also in late August and September, separated by a mild anti-cyclonic drought in July. In South China and the Philippines the trade winds prevail in the October-April (winter) period, strengthened by the regional, often gusty, outflow of air from the stationary Siberian anticyclone. Their disappearance and replacement by opposite (southwesterly) winds in the MaySeptember (summer) period is the essence of the monsoon. In any case, these


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monsoon streams are quite shallow, about 1,500 m in winter and 2,000 m in summer. They bring rain only when subject to considerable cooling, as happens to the windward anywhere on the steep slopes of the Philippines and Taiwan. On the larger islands there are contrasting effects, the slopes facing west receiving most of the rain from May to October and a drought from December to April, whereas the slopes facing east receive orographic rains (those produced when moist air is forced to rise by topography) from September to April and mainly convectional rains from May to October. In Vietnam and Thailand the summer monsoon is more strongly developed because of the wider expanses of overheated land. The southwesterly stream flows from May to October, reaching a thickness of four to five km; it brings plentiful but not extraordinary rainfall. November to February is the cool, dry season, and March to April the hot, dry one; in the far south the coolness is but relative. Along the east coast and on the eastward slopes more rain is brought by the winter monsoon. In the summer, somewhere between Thailand and Kampuchea in the interior, there may be a faint line of convergence between the southwesterly IndianBurmese monsoon and the southeasterly Malaysian Monsoon: Winds are weak over Indonesia because of the expanses of water and the low latitude, but their seasonal reversal is definite. From April to October the Australian southeasterly air flows, whereas north of the Equator it becomes a southwesterly. It generally maintains its dryness over the islands closer to Australia, but farther north it carries increasing amounts of moisture. The northeasterly flow from Asia, which becomes northwesterly south of the Equator, is laden with moisture when it reaches Indonesia, bringing cloudy and rainy weather between November and May. The wettest months are December in most of Sumatra and January elsewhere, but rainfall patterns are highly localized. In Java, for instance, at sea level alone there are two major regions, an “equatorial” west with no dry season and a “monsoon” east with extreme drought in August and September. Because of its relatively small size and compact shape, Australia shows relatively simple monsoon patterns. The north shore is subject to a clear-cut wind reversal between summer (November-April, north-westerly) and winter (MaySeptember, southeasterly), but with two definite limitations: first, the northwesterly, rain-bearing monsoon wind is often held offshore and is most likely to override the land to any depth during January and February; and second, even in summer there often are prolonged spells of southeasterly trade winds issuing from traveling anticyclones, separating the brief monsoon incursions. The Australian summer monsoon is thus typical in direction and weather type but quite imperfect in frequency and persistence. Its thickness is usually less than 1,500 m over the sea and 2,000-2,500 m over the land. Much less typical are the marginal monsoon manifestations. On the northwest coast there frequently is a northwesterly airflow in the summer (December-March), as opposed to the winter south-easterlies, but this stream is very shallow and does not bring any rain—i.e. its weather is not monsoon even though its direction is so.


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On the northeast coast the onshore air is humid and brings rain, but its direction is only partly modified in summer. It comes in mostly as a northeasterly, while at other times it is mostly southeasterly. 4.3

Indian Climate

It is clear from the above presentations, the climate of India comprises a wide range of weather conditions across a large geographic scale and varied topography, making generalizations difficult. Analyzed according to the Koppen System of classification, India hosts six major climatic subtypes [Figure 4c], ranging from desert in the west, to alpine tundra and glaciers in the north, to humid tropical regions supporting rainforests in the southwest and the island territories. Many regions have starkly different microclimates. The nation has four seasons: winter (January and February), summer (March to May), a monsoon (rainy) season (June to September), and a post-monsoon period (October to December). India’s unique geography and geology strongly influence its climate; this is particularly true of the “Himalayas” in the North and the “Thar Desert” in the Northwest. The Himalayas act as a barrier to the frigid katabatic winds flowing down from Central Asia. Thus, North India is kept warm or only mildly cold during winter; in summer, the same phenomenon makes India relatively hot. Although the Tropic of Cancer — the boundary between the tropics and subtropics—passes through the middle of India, the whole country is considered to be tropical. As in much of the tropics, monsoon and other weather conditions in India are unstable: major droughts, floods, cyclones and other natural disasters are sporadic, but have killed or displaced millions. Climatic diversity in India makes the analysis of these issues complex. However, the Indian climate is modified by topographical patterns prevailing over different parts of India. 4.3.1 Types of Climates India is home to an extraordinary variety of climatic regions, ranging from tropical in the south to temperate and alpine in the Himalayan North, where elevated regions receive sustained winter snowfall. The nation’s climate is strongly influenced by the Himalayas and the Thar Desert. The Himalayas, along with the Hindu Kush mountains in Pakistan, prevent cold Central Asian katabatic winds from blowing in, keeping the bulk of the Indian subcontinent warmer than most locations at similar latitudes. Simultaneously, the Thar Desert plays a role in attracting moisture-laden Southwest Summer Monsoon winds that, between June and October, provide the majority of India’s rainfall. Four major climatic groupings predominate, into which fall seven climatic zones that are defined on the basis of such traits as temperature and precipitation. Groupings are assigned codes according to the Köppen climate classification system [Figure 4c]. Tropical Wet: A tropical rainy climate covers regions experiencing persistent warm or high temperatures, which normally do not fall below 18 oC (64 oF). India hosts two climatic subtypes that fall under this group. The most humid is the tropical wet monsoon climate that covers a strip of southwestern lowlands abutting the


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Malabar Coast, the Western Ghats, and southern Assam. India’s two island territories, Lakshadweep and the Andaman and Nicobar Islands, are also subject to this climate. Characterized by moderate to high year-round temperatures, even in the foothills, its rainfall is seasonal but heavy—typically above 2,000 mm (79 in) per year. Most rainfall occurs between May and November; this is adequate for the maintenance of lush forests and other vegetation throughout the remainder of the year. December to March is the driest months, when days with precipitation are rare. The heavy monsoon rains are responsible for the extremely biodiverse tropical wet forests of these regions. In India, a tropical wet and dry climate is more common. Significantly drier than tropical wet zones, it prevails over most of inland peninsular India except for a semi-arid rain shadow east of the Western Ghats. Winter and early summer are long, dry periods with temperatures averaging above 18 °C (64 °F). Summer is exceptionally hot; temperatures in low-lying areas may exceed 50 °C (122 °F) during May, leading to heat waves that can each kill hundreds of Indians. The rainy season lasts from June to September; annual rainfall averages between 750–1500 mm (30–59 in) across the region. Once the dry northeast monsoon begins in September, most precipitation in India falls on Tamil Nadu, leaving other states comparatively dry. Tropical Dry: A tropical arid and semi-arid climate dominates regions where the rate of moisture loss through evapotranspiration exceeds that from precipitation; it is subdivided into three climatic subtypes. The first, a tropical semi-arid steppe climate, predominates over a long stretch of land south of Tropic of Cancer and east of the Western Ghats and the Cardamom Hills. The region, which includes Karnataka, inland Tamil Nadu, western Andhra Pradesh, and central Maharashtra, gets between 400–750 mm (16–30 in) annually. It is drought-prone, as it tends to have less reliable rainfall due to sporadic lateness or failure of the southwest monsoon. North of the Krishna River, the summer monsoon is responsible for most rainfall; to the south, significant post-monsoon rainfall also occurs in October and November. In December, the coldest month, temperatures still average around 20– 24 °C (68–75 °F). The months between March to May are hot and dry; mean monthly temperatures hover around 32 °C, with 320 mm (13 in) precipitation. Hence, without artificial irrigation, this region is not suitable for permanent agriculture. The Ran of Kutch, a vast salt marsh south of the Thar Desert in Gujarat. During the monsoon season, the region fills with standing waters. Most of western Rajasthan experiences an arid climatic regime. Cloudburst is responsible for virtually all of the region’s annual precipitation, which totals less than 300 mm (12 in). Such bursts happen when monsoon winds sweep into the region during July, August, and September. Such rainfall is highly erratic; regions experiencing rainfall one year may not see precipitation for the next couple of years or so. Atmospheric moisture is largely prevented from precipitating due to continuous downdrafts and other factors. The summer months of May and June are exceptionally hot; mean monthly temperatures in the region hover around 35 °C (95 °F), with daily maxima occasionally topping 50 °C (122 °F). During winters, temperatures in some areas can drop below freezing due to waves of cold


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air from Central Asia. There is a large diurnal range of about 14 °C (57 °F) during summer; this widens by several degrees during winter. East of the Thar Desert, the region running from Punjab and Haryana to Kathiawar experiences a tropical and sub-tropical steppe climate. The zone, a transitional climatic region separating tropical desert from humid sub-tropical savanna and forests, experiences temperatures that are less extreme than those of the desert. Average annual rainfall is 30–65 cm (12-26 in), but is very unreliable; as in much of the rest of India, the southwest monsoon accounts for most precipitation. Daily summer temperature maxima rise to around 40 °C (104 °F). The resulting natural vegetation typically comprises short, coarse grasses. Subtropical Humid: Most of Northeast India and much of North India are subject to a humid sub-tropical climate. Though they experience hot summers, temperatures during the coldest months may fall as low as 0 °C (32 °F). Due to ample monsoon rains, India has only one subtype of this climate, Cfa (under the Köppen system). In most of this region, there is very little precipitation during the winter, owing to powerful anticyclonic and katabatic (downward-flowing) winds from Central Asia. Due to the region’s proximity to the Himalayas, it experiences elevated prevailing wind speeds, again from the influence of Central Asian katabatic movements. Humid subtropical regions are subject to pronounced dry winters. Winter rainfall— and occasionally snowfall—is associated with large storm systems such as “Nor’westers” and “Western Disturbances”; the latter are steered by westerlies towards the Himalayas. Most summer rainfall occurs during powerful thunderstorms associated with the southwest summer monsoon; occasional tropical cyclones also contribute. Annual rainfall ranges from less than 1,000 mm (39 in) in the west to over 2,500 mm (98 in) in parts of the northeast. As most of this region is far from the ocean, the wide temperature swings more characteristic of a continental climate predominate; the swings are wider than in those in tropical wet regions, ranging from 24 °C (75 °F) in north-central India to 27 °C (81 °F) in the east. Montane: Pangone Lake in Ladakh, an arid montane region lying deep within the Himalayas. India’s northernmost fringes are subject to a montane, or alpine, climate. In the Himalayas, the rate at which an air mass’s temperature falls per km (3,281 ft) of altitude gained (the adiabatic lapse rate) is 5.1 °C/km. In terms of environmental lapse rate, ambient temperatures fall by 0.6 °C (1.1 °F) for every 100 m (328 ft) rise in altitude. Thus, climates ranging from nearly tropical in the foothills to tundra above the snow line can coexist within several dozen miles of each other. Sharp temperature contrasts between sunny and shady slopes, high diurnal temperature variability, temperature inversions, and altitude-dependent variability in rainfall are also common. The northern side of the western Himalayas, also known as the trans-Himalayan belt, is a region of barren, arid, frigid, and windblown wastelands. Most precipitation occurs as snowfall during the late winter and spring months. Areas south of the Himalayas are largely protected from cold winter winds coming in from the Asian interior. The leeward side (northern face) of the mountains receives less rain while the southern slopes, well exposed to the monsoon, get heavy rainfall. Areas situated at elevations of 1,070–2,290 m (3,510–


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7,510 ft) receive the heaviest rainfall, which decreases rapidly at elevations above 2,290 m (7,513 ft). The Himalayas experience their heaviest snowfall between December and February and at elevations above 1,500 m (4,921 ft). Snowfall increases with elevation by up to several dozen mm per 100 m (~2 in; 330 ft) increase. Elevations above 5,000 m (16,404 ft) never experience rain; all precipitation falls as snow. 4.3.2 Seasons The India Meteorological Department (IMD) designates four official seasons: Winter season, occurring between January and March. The year’s coldest months are December and January, when temperatures average around 10–15 °C (50– 59 °F) in the northwest; temperatures rise as one proceeds towards the equator, peaking around 20–25 °C (68–77 °F) in mainland India’s southeast. Summer or pre-monsoon season, lasting from March to June (April to July in northwestern India). In western and southern regions, the hottest month is April; for northern regions, May is the hottest month. Temperatures average around 32–40 °C (90– 104 °F) in most of the interior. June to September is the Monsoon or rainy season, which is dominated by the humid southwest summer monsoon that slowly sweeps across the country beginning in late May or early June. Monsoon rains begin [Figure 4d] to recede from North India at the beginning of October. October to December is the Post-monsoon season, during which period the South India typically receives more precipitation. Monsoon rains begin to recede from North India at the beginning of October. In northwestern India, October and November are usually cloudless. Parts of the country experience the dry northeast monsoon. The Himalayan states, being more temperate, experience an additional two seasons: autumn and spring. Traditionally, Indians note six seasons, each about two months long. These are the spring, summer, and monsoon season, early autumn, late autumn, and winter. Winter: Once the monsoons subside, average temperatures gradually fall across India. As the Sun’s vertical rays move south of the equator, most of the country experiences moderately cool weather; temperatures change by about 0.6 °C (1.35 °F) per degree of latitude. December and January are the coldest months, with mean temperatures of 10–15 °C (50–59 °F) in Indian Himalayas. Mean temperatures are higher in the east and south, where they reach 20–25 °C (68– 77 °F). In northwestern India, virtually cloudless conditions prevail in October and November, resulting in wide diurnal temperature swings; as in much of the Deccan Plateau, they range between 16–20 °C (61–68 °F). However, from March to May, “western disturbances” bring heavy bursts of rain and snow. These extra-tropical low-pressure systems originate in the eastern Mediterranean Sea. They are carried towards India by the subtropical westerlies, which are the prevailing winds blowing at North India’s range of latitude. Once their passage is hindered by the Himalayas, they are unable to proceed further, and they release significant precipitation over the southern Himalayas. The three Himalayan states (Jammu and Kashmir in the extreme north, Himachal Pradesh,


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and Uttarkhand) experience heavy snowfall; in Jammu and Kashmir, blizzards occur regularly, disrupting travel and other activities. The rest of North India, including the Indo-Gangetic Plain, almost never receives snow. However, in the plains, temperatures occasionally fall below freezing, though never for more one or two days. Winter highs in Delhi range from 16 °C (61 °F) to 21 °C (70 °F). Nighttime temperatures average 2–8 °C (36–46 °F). In the Punjab plains, lows can fall below freezing, dropping to around -6 °C (21 °F) in Amritsar. Frost sometimes occurs, but the hallmark of the season is the notorious fog, which frequently disrupts daily life; fog grows thick enough to hinder visibility and disrupt air travel 15–20 days annually. Eastern India’s climate is much milder, experiencing moderately warm days and cool nights. Highs range from 23 °C (73 °F) in Patna to 26 °C (79 °F) in Kolkata (Calcutta); lows average from 8 °C (46 °F) in Patna to 14 °C (57 °F) in Kolkata. Frigid winds from the Himalayas can depress temperatures near the Brahmaputra River. The two Himalayan states in the east, Sikkim and Arunachal Pradesh, receive substantial snowfall. The extreme north of West Bengal, centered on Darjeeling, also experiences snowfall, but only rarely. In South India, particularly the hinterland of Maharashtra, Madhya Pradesh, parts of Karnataka, and Andhra Pradesh, somewhat cooler weather prevails. Minimum temperatures in western Maharashtra, Madhya Pradesh and Chattisgarh hover around 10 °C (50 °F); in the southern Deccan Plateau, they reach 16 °C (61 °F). Coastal areas, especially those near the Coromandal Coast, and low-elevation interior tracts are warm, with daily high temperatures of 30 °C (86 °F) and lows of around 21 °C (70 °F). The Western Ghats, including the Nilgiri Range, are exceptional; there, lows can fall below freezing. This compares with a range of 12–14 °C (54– 57 °F) on the Malabar Coast; there, as is the case for other coastal areas, the Indian Ocean exerts a strong moderating influence on weather. Summer: Summer in northwestern India lasts from April to July, and in the rest of the country from March to June. The temperatures in the north rise as the vertical rays of the Sun reach the Tropic of Cancer. The hottest month for the western and southern regions of the country is April; for most of North India, it is May. Temperatures of 50 °C (122 °F) and higher have been recorded in parts of India during this season In cooler regions of North India, immense pre-monsoon squallline thunderstorms, known locally as “Nor’westers”, commonly drop large hailstones. Near the coast the temperature hovers around 36 °C (97 °F), and the proximity of the sea increases the level of humidity. In southern India, the temperatures are higher on the east coast by a few degrees compared to the west coast. By May, most of the Indian interior experiences mean temperatures over 32 °C (90 °F), while maximum temperatures often exceed 40 °C (104 °F). In the hot months of April and May, western disturbances, with their cooling influence, may still arrive, but rapidly diminish in frequency as summer progresses. Notably, a higher frequency of such disturbances in April correlates with a delayed monsoon onset (thus extending summer) in northwest India. In eastern India, monsoon onset dates have been steadily advancing over the past several decades, resulting in shorter summers there.


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Altitude affects the temperature to a large extent, with higher parts of the Deccan Plateau and other areas being relatively cooler. Hill Stations, such as Ootacamund (“Ooty”) in the Western Ghats and Kalimpong in the eastern Himalayas, with average maximum temperatures of around 25 °C (77 °F), offer some respite from the heat. At lower elevations, in parts of northern and western India, a strong, hot, and dry wind known as the Loo blows in from the west during the daytime; with very high temperatures, in some cases up to around 45 °C (113 °F); it can cause fatal cases of sunstroke Tornadoes may also occur, concentrated in a corridor stretching from northeastern India towards Pakistan. They are rare, however; only several dozen have been reported since 1835. Monsoon: The southwest summer monsoon, a four-month period when massive convective thunderstorms dominate India’s weather, is Earth’s most valuable wet season. It results from the southeast trade winds originating from a high-pressure mass centered over the southern Indian Ocean; attracted by a low-pressure region centered over South Asia, it gives rise to surface winds that ferry humid air into India from the southwest. These inflows ultimately result from a northward shift of the local jet stream, which itself results from rising summer temperatures over Tibet and the Indian subcontinent. The void left by the jet stream, which switches from a route just south of the Himalayas to one tracking north of Tibet, then attracts warm, humid air. The main factor behind this shift is the high summer temperature difference between Central Asia and the Indian Ocean. This is accompanied by a seasonal excursion of the normally equatorial ITCZ, a low-pressure belt of highly unstable weather, northward towards India. This system intensified to its present strength as a result of the Tibetan Plateau’s uplift, which accompanied the Eocene-Oligocene transition event, a major episode of global cooling and aridification, which occurred 34–49 mya. The southwest monsoon arrives in two branches: the Bay of Bengal branch and the Arabian sea branch. The latter extends toward a low-pressure area over the Thar Desert and is roughly three times stronger than the Bay of Bengal branch. The monsoon usually breaks over Indian territory by around 25 May, when it lashes the Andaman and Nicobar Islands in the Bay of Bengal. It strikes the Indian mainland around 1 June supplies over 80% of India’s annual rainfall. First appearing near the Malabar Coast of Kerala [Figure 4d]. By 10 June, it reaches Mumbai; it appears over Delhi by 2 July. The Bay of Bengal branch, which hugs the Coromandal Coast between Cape Comorin and Orissa, swerves to the northwest. The Arabian Sea branch moves northeast towards the Himalayas. By the first week of July, the entire country experiences monsoon rain; on average, South India receives more rainfall than North India. However, Northeast India receives the most precipitation. Monsoon clouds begin retreating from North India by the end of August; it withdraws from Mumbai by 5 October. As India further cools during September, the southwest monsoon weakens. By the end of November, it has left the country. Monsoon rains impact the health of the Indian economy; as Indian agriculture employs 600 million people and composes 20% of the national GDP good monsoons correlate with a booming economy. Weak or failed monsoons (droughts) result in


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widespread agricultural losses and substantially hinder overall economic growth. The rains reduce temperatures and replenish groundwater tables, rivers, and lakes. Post-monsoon: During the post-monsoon months of October to December, a different monsoon cycle, the northeast (or “retreating”) monsoon, brings dry, cool, and dense Central Asian air masses to large parts of India. Winds spill across the Himalayas and flow to the southwest across the country, resulting in clear, sunny skies. Though the IMD and other sources refer to this period as a fourth (“postmonsoon”) season, other sources designate only three seasons. Depending on location, this period lasts from October to November, after the southwest monsoon has peaked. Less and less precipitation falls, and vegetation begins to dry out. In most parts of India, this period marks the transition from wet to dry seasonal conditions. Average daily maximum temperatures range between 28 °C and 34 °C (82–93 °F). Reddy (1978) presented weather associated with western disturbances, which are of importance in winter both in terms of temperature and rainfall.. The northeast monsoon, which begins in September, lasts through the postmonsoon seasons, and only ends in March, carries winds that have already lost their moisture while crossing central Asia and the vast rain shadow region lying north of the Himalayas. They cross India diagonally from northeast to southwest. However, the large indentation made by the Bay of Bengal into India’s eastern coast means that the flows are humidified before reaching Cape Comorin and rest of Tamil Nadu, meaning that the state, and also some parts of Kerala, experience significant precipitation in the post-monsoon and winter periods. However, parts of West Bengal, Orissa, Andhra Pradesh, Karnataka and Northeast India also receive minor precipitation from the northeast monsoon. Figures 4 e & 4 f presents the rainfall and temperature patterns in India. 4.3.3 Disasters Climate-related natural disasters cause massive losses of Indian life and property. Droughts, flash floods, cyclones, avalanches, landslides brought on by torrential rains, and snowstorms pose the greatest threats. Other dangers include frequent summer dust storms, which usually track from north to south; they cause extensive property damage in North India and deposit large amounts of dust from arid regions. Hail is also common in parts of India, causing severe damage to standing crops such as rice and wheat. Floods and Landslides: In the Lower Himalaya, landslides are common. The young age of the region’s hills result in labile rock formations, which are susceptible to slippages. Rising population and development pressures, particularly from logging and tourism, cause deforestation. The result, denuded hillsides, exacerbates the severity of landslides, since tree cover impedes the downhill flow of water. Parts of the Western Ghats also suffer from low-intensity landslides. Avalanches occur in Kashmir, Himachal Pradesh, and Sikkim. Floods are the most common natural disaster in India. The heavy southwest monsoon rains cause the Brahmaputra and other rivers to distend their banks,


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often flooding surrounding areas. Though they provide rice paddy farmers with a largely dependable source of natural irrigation and fertilisation, the floods can kill thousands and displace millions. Excess, erratic, or untimely monsoon rainfall may also wash away or otherwise ruin crops. Almost all of India is flood-prone, and extreme precipitation events, such as flash floods and torrential rains, have become increasingly common in central India over the past several decades, coinciding with rising temperatures. Mean annual precipitation totals have remained steady due to the declining frequency of weather systems that generate moderate amount of rain. Cyclones: Tropical cyclones, which are severe storms spun off from the ITCZ, may affect thousands of Indians living in coastal regions. Tropical cyclogenesis is particularly common in the northern reaches of the Indian Ocean in and around the Bay of Bengal. Cyclones bring with them heavy rains, Storm surges, and winds that often cut affected areas off from relief and supplies. In the North Indian Ocean Basin, the cyclone season runs from April to December, with peak activity between May and November [Table 5]. Each year, an average of eight storms with sustained wind speeds greater than 63 km/h (39 mph) form; of these, two strengthen into true tropical cyclones, which have sustained gusts greater than 117 km/h (73 mph). On average, a major Category 3 or higher) cyclone develops every other year. During summer, the Bay of Bengal is subject to intense heating, giving rise to humid and unstable air masses that produce cyclones. Many powerful cyclones, including the 1737 Calcutta cyclone, the 1970 Bhola cyclone, and the 1991 Bangladesh cyclone, have led to widespread devastation along parts of the eastern coast of India and neighboring Bangladesh. Widespread death and property destruction are reported every year in exposed coastal states such as Andhra Pradesh, Orissa, Tamil Nadu, and West Bengal. India’s western coast, bordering the more placid Arabian Sea, experiences cyclones only rarely; these mainly strike Gujarat and, less frequently, Kerala. Table 5: Monthly cyclonic disturbances in Arabian sea and Bay of Bengal during 1891-1990 Number of disturbances recorded Bay OF Bengal

Arabian sea

Month

D

CS

SCS

T

D

CS

SCS

T

January

13

4

2

19

4

2

0

6

February

3

0

1

4

0

0

0

0

March

1

2

2

5

1

0

0

1

April

8

11

10

29

2

2

4

8

May

32

15

35

82

11

5

15

31

June

84

33

5

122

27

6

12

45

July

118

34

7

159

15

3

0

18

August

161

27

3

191

5

2

0

7

Climate Change: Myths & Realities September

151

October

73 25

14

Dr. S Jeevananda Reddy 190

10

4

3

17

104

44

34

182

28

13

12

53

November

55

42

53

150

32

6

20

58

December

37

23

19

79

8

4

2

14

767

260

185

1212

143

47

68

258

Total

Note:

D = depression, CS = cyclonic storm, SCS = severe cyclonic storm & T = total


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In terms of damage and loss of life, a super-cyclone that struck Orissa on 29 October 1999, was the worst in more than a quarter-century. With peak winds of 160 miles per hour (257 km/h), it was the equivalent of a Category 5 Hurricane Almost two million people were left homeless; another 20 million people lives were disrupted by the cyclone. Officially, 9,803 people died from the storm; unofficial estimates place the death toll at over 10,000. Droughts: Indian agriculture is heavily dependent on the monsoon as a source of water. In some parts of India, the failure of the monsoons result in water shortages, resulting in below-average crop yields [Figures 4g & 4h]. This is particularly true of major drought-prone regions such as southern and eastern Maharashtra, northern Karnataka, Andhra Pradesh, Orissa, Gujarat, and Rajasthan. In the past, droughts have periodically led to major Indian famines. These include the Bangla famine of 1770, in which up to one third of the population in affected areas died; the 1876– 1877 famine, in which over five million people died; the 1899 famine, in which over 4.5 million died; and the Bengal famine of 1943, in which over five million died from starvation and famine-related illnesses. All such episodes of severe drought correlate with El Nino- Souhern Oscillation (ENSO) events. El Niño-related droughts have also been implicated in periodic declines in Indian agricultural output. Nevertheless, ENSO events that have coincided with abnormally high sea surfaces temperatures in the Indian Ocean—in one instance during 1997 and 1998 by up to 3 °C (5 °F)—have resulted in increased


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Oceanic evaporation, resulting in unusually wet weather across India. Such anomalies have occurred during a sustained warm spell that began in the 1990s. A contrasting phenomenon is that, instead of the usual high pressure air mass over the southern Indian Ocean, an ENSO-related oceanic low pressure convergence center forms; it then continually pulls dry air from Central Asia, desiccating India during what should have been the humid summer monsoon season. This reversed airflow causes India’s droughts. The extent that an ENSO event raises sea surfaces in the central Pacific Ocean influences the degree of drought. However, it is not well proved theory. Extremes: The average annual precipitation of 11,871 mm (467 in) in the village of Mawsynram, in the hilly northeastern state of Meghalaya, is the highest recorded in Asia, and possibly on the Earth. The village, which sits at an elevation of 1,401 m (4,596 ft), benefits from its proximity to both the Himalayas and the Bay of Bengal. However, since the town of Cherrapunji, 5 km (3 mi) to the east, is the nearest town to host a meteorological office (none has ever existed in Mawsynram), it is officially credited as being the world’s wettest place. In recent years, the Cherrapunji-Mawsynram region has averaged 9,296 mm (366 in) of rain annually, though Cherrapunji has had at least one period of daily rainfall that lasted almost two years. India’s highest recorded one-day rainfall total occurred on 26 July 2005, when Mumbai received more than 650 mm (26 in); the massive flooding that resulted killed over 900 people. In terms of snowfall, regions of Jammur and Kashmir, such as Baramulla in the east and the Pir Panjal Range in the southeast, experience exceptionally heavy snowfall. Kashmir’s highest recorded monthly snowfall occurred in February of 1967, when 8.4 m (331 in) fell in Gulmarg, though the IMD has recorded snowdrifts up to 12 m (39 ft) in several Kashmiri districts. In February of 2005, more than 200 people died when, in four days, a western disturbance brought up to 2 m (7 ft) of snowfall to parts of the state.


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Chapter 5

Climate Change 5.1

Introduction

One issue that received wide media coverage relates to recent spurt in natural disasters felt globally such as Earthquakes/Tsunamis, cyclones/Typhoons/Hurricanes, floods & droughts, heat & cold waves, etc. These were attributed to man-induced changes to climate, more particularly to the so-called global warming. The politicians, bureaucrats, environmentalists, NGOs are giving so much importance to a phenomena that is not well understood by themselves but at the same time they are not giving the same and equal importance to direct affects of pollution on air, water, soil and food and their consequent effects on human, animal and plant life, that is on life forms. It is just because the climate change aspects of pollution, known as indirect effects, have billions of dollars to share but the same is not the case in the area of direct consequences of pollution by which common man suffers, more particularly in developing countries. Extreme natural events become disasters when they affect settlements, economic and social activities. Whether a given phenomenon is equated to a disaster does not depend so much on its intensity as on its impact on society. The public measure the intensity of the system based on deaths and destruction of property. The damage is far less before 1960s when compared to damages after 60s in terms of numerical numbers but when we consider the percent figures of that time they are not different. Therefore, in all these cases the place of occurrence plays an important role in terms of damage. Scientific point of view the intensity/severity of natural disaster is different from the public point of view. The public experience present a short span of years while scientists experience relates to a long period of historical scale of years. Media is more interested in the view point of public rather than scientists view point, because the former group represent numerically far more in number than the later group and at the same time gives big hype. This is exactly what is happening with Intergovernmental Panel on Climate Change (IPCC) perspective of climate change. With this every thing has become unusual and try to attribute to some thing they don’t have the comprehensive knowledge like a blind man using a light pole. In floods and droughts in recent years political floods and droughts play important role over the scientific floods and droughts – that is motivated floods and droughts gets more publicity. Most unfortunately, man on the street to Editor of scientific magazines talk of climate change at the same wavelength, and thus science became a scapegoat!!! The same can be said with modern climate change research. The group that is using the modern model based global warming and their impact get big hype compared to people engaged in understanding the nature in its’ true


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perspective like natural rhythm that help agriculture in true sense. In the modern world of Western based science, awards/rewards go to modelers, promotions go to modelers!!! People talks of science are considered as outcastes. Therefore, it is the responsibility of scientific groups to clear this ambiguity, so that it is easy to understand the impact of such events on environment and thereby on human, animal and plant life under different time and space scales. The same is evident in modern politics. When a famous person from a particular field with mass connection, when he says some thing people blindly believe him with out knowing his real background. So, it is easy to cheat gullible public. A known enemy is better than an unknown enemy. Here media plays the spoilsport. Let us see how, the media without understanding the basics create controversies!!! A recent report says, “In the debate on global warming, the data on the climate of Antarctica has been distorted, at different times, by both sides. As a polar researcher caught in the middle, I would like to set the record straight. In January 2002, a research paper about Antarctic temperatures, of which I was the lead author, appeared in the journal Nature. At the time, the Antarctic Peninsula was warming, and many people assumed that meant the climate on the entire continent was heating up, as the Arctic was. But the Antarctic Peninsula represents only about 15 percent of the continents landmass, so it could not tell the whole story of Antarctic climate. Our paper made the continental picture clearer. My research colleagues and I found that from 1986 to 2000, one small, ice-free area of the Antarctic mainland had actually cooled. Our report also analyzed temperatures for the mainland in such a way as to remove the influence of the peninsula warming and found that, from 1986 to 2000, more of the continent had cooled than had warmed. Our summary statement pointed out how the cooling trend posed challenges to models of Antarctic climate and ecosystem change. Newspaper and television reports focused on this part of the paper. And many news and opinion writers linked our study with another bit of polar research published that month, in Science, showing that part of Antarctica’s ice sheet had been thickening and erroneously concluded that the Earth was not warming at all. Scientific findings run counter to theory of global warming, said a headline on an editorial in The San Diego Union-Tribune. One conservative commentator wrote, It is ironic that two studies suggesting that a new Ice Age may be under way may end the global warming debate. In a rebuttal in The Providence Journal, in Rhode Island, the lead author of the Science paper and I explained that our studies offered no evidence that the earth was cooling. But the misinterpretation had already become legend, and in the four and half years since, it has only grown. Our results have been misused as evidence against global warming by Michael Crichton in his novel State of Fear and by Ann Coulter in her latest book, Godless: The Church of Liberalism. Search my name on the Web, and you will find pages of links to everything from climate discussion groups to Senate policy committee documents all citing my 2002 study as reason to doubt that the Earth is warming. One recent Web column even put words in my mouth. I have never said that the unexpected colder climate in Antarctica may possibly be signaling a lessening of the current global warming cycle. I have never thought such a thing either.


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Our study did find that 58 percent of Antarctica cooled from 1986 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the ozone hole over that continent. These models, conspicuously missing from the warming-skeptic literature, suggest that as the ozone hole heals thanks to worldwide bans on ozone-destroying chemicals all of Antarctica is likely to warm with the rest of the planet. Also missing from the skeptics’ arguments is the debate over our conclusions. Another group of researchers who took a different approach found no clear cooling trend in Antarctica. We still stand by our results for the period we analyzed, but unbiased reporting would acknowledge differences of scientific opinion. The disappointing thing is that we are even debating the direction of climate change on this globally important continent. And it may not end until we have more weather stations on Antarctica and longer-term data that demonstrate a clear trend. In the meantime, I would like to remove my name from the list of scientists who dispute global warming. I know my coauthors would as well”. 5.2

What is Climate Change?

“Climate Change” is a change in the “average weather”. Climate refers to the weather over very long periods, while the weather is what we experience daily. In the past climate change refers to the “Systematic Natural Rhythm”, expressed in the form of cycles with different time scales. In recent years, it invariably refers to one component of man-induced changes, expressed in the form of global warming “trend”. The major culprit in this sordid episode is the Intergovernmental Panel on Climate Change [IPCC). As long as it was in the hands of scientific organization, namely World Meteorological Organization [WMO] it was in the hands of scientific groups. Once it was put in the hands of a political organization such as IPCC it went into the hands of non-scientific-vested groups. In this, public relation campaign by vested groups played major role over the science. It is the greatest tragedy in the annals of history of science. It is clear from the way IPCC gave weight to majority individual/organizations opinion without valid scientific base and tried to manipulate science to prove its’ point. In the same line, Indian scientists are enthusiastic in “thinking locally and acting globally” instead “thinking globally and acting locally”. Basically because of this attitude the scientists invariably give weight to Westerners unproved-semi-empirical models. These are far from ground realities. By this way the responsible scientific community leading the planners in wrong way. The Public Relation Campaign in this direction by vested groups “fetched” Noble Prize to IPCC & Al Gore former Vice-President of USA. This has given a big hype to the unproven arguments. Even when authors of the theory are skeptical about the issue, yet the public relation campaign groups became more aggressive in their campaign, causing irrevocable damage to science of climate change. It turned into another political vote catching type campaign in developing countries. Man within his understanding of the subject/nature formulates models with several unknown factors missing; while ground truth is the result of integrated


79


effect of known and unknown factors. This exactly what is happening in the global warming and its’ so called impact. While making sweeping conclusions based on such imperfect mathematical models one must be cautious and careful. At the same time while presenting results, one must not present/discuss in isolation but present/discuss in an integrated manner. That is exactly what is needed for planning. In fact weather plays major role in Indian economic context, as it is an agriculture nation in which agriculture is driven by weather. For example, Reddy (1995a) presented 3 points of difference of series of articles by top scientific groups of the world on the importance of radiation term in crop growth, where one author says yes/correct and the other author says no/ not correct, from the series of discussion papers published in 1994 in Agric. For. Meteorol., 68:213-242. After integrating these studies in holistic manner, Reddy come up with more pragmatic and practical approach to be useful in real conditions, by explaining the limitations of individual approaches by taking components in isolation. Reddy (1995b) reviewed the result of McKenny & Rosenberg (1993) results estimated using GISS & GFDL general circulation models for doubled


80


atmospheric CO 2 , on the expected climate change induced effects on meteorological parameters (Figure 5a) that are inputs into crop models – Down To Earth presented sensitivity of land suitable for cereal production to climate change (Figure 5b). Reddy observed changes observed in parameters are far less than those expected from the model-induced error ranges. That is, first the model’s applicability in holistic condition must be proven beyond doubt, which the authors have not attempted. Like in the climate change & genetically modified crops of MNCs, there are large vested interest groups that present public relation campaign in artificial rain making (cloud seeding) by simply highlighting the isolated results. Reddy (2004)


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presented a review of the literature on cloud seeding in a holistic context and observed “The experiments so far conducted suggested that, with few exceptions, conclusive cloud seeding is not producing the desired results. The Indian experience is not much different from this conclusion. It is important to note that a successful experiment in one region does not guarantee that seeding in another region will be successful unless environmental conditions are replicated as well as the methodology of seeding. Such a situation is hypothetical”. To counter this, the seeding agencies invariably seed a severe-active synoptic system and present the results as the outcome of cloud seeding operations and without showing how much rainfall was reduced by seeding a strong-active system that give copious rainfall in the down wind direction in normal circumstances. Here also isolated things are attributed to holistic situation by falsifying the facts before ignorant politicians. It has become a common reporting saying “global warming is the increase in the average temperature of the Earth’s near-surface air and Oceans in recent decades and its projected continuation. The IPCC concludes most of the observed increase in globally average temperature since the mid-twentieth Century is very likely due to the observed increase in anthropogenic greenhouse gases concentrations via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a smaller warming effect and pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least thirty Scientific Societies and Academies of Science. While the individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with IPCC main conclusion”. The basic question to be answered from such pronouncements is: scientific studies should be based on what many accepted or endorsed; or based on what is scientifically correct? But unfortunately, the public Relation activists put emphasis in the number game!!! In this connection, let me give three examples from my experience (Reddy, 1983; Reddy, 1983-84; Reddy, 1993; Reddy, 1995a; Reddy, 2002b): Firstly, while I was a Ph.D. student in Australia, it became a big issue why I am not using a particular model, which is being in wide use in Australia including a student from my department completed his Ph.D. thesis using that model. They asked my explanation on this. I presented to them stating that this is a static model. Discarding his thesis, then the Ph.D. student took up another topic and completed his Ph.D. We both received our Ph.D.s in 1985. This is science!!! Secondly, FAO Headquarters asked my explanation in writing, why I am using a different model in my work instead of FAO-Agro-ecological zones concept as an FAO Expert. I gave my scientific report stating that this is a static model. After hearing my explanation, they asked me to modify the model. I did not do it as it has some inherent weaknesses. In fact when I presented a talk on the agroclimatic classification developed by me in 1981, the scientist who was involved in the development of the FAO model was also present at my talk. He left the organization; he adopted over simplified version of mine and used monthly data


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instead weekly data, which was used in my concept. With this the model became static. This is science!!! Thirdly, to present the solar radiation impact on crop, three different groups started publishing articles with contradicting observations. This was clarified by presenting the results in an integrated manner saying that all are correct (Reddy, 1995). This is science but not “numerical number” as adopted by IPCC to bulldoze the science!!! Dr. James E. Hansen, Director of Space Studies at the National Aeronautics and Space Administration was a principal author of one of the first papers spelling out the links between rising atmospheric levels of Carbon Dioxide (CO2) and rising global temperatures as back as 1981. In 2000, he along with his colleagues reported in the proceedings of the National Academy of Sciences, USA that the global warming seen in recent decades was not caused by CO2 but mainly by other heat trapping emissions Methane [CH4], CFCs, black particles of diesel & coal soot, and other compounds that create the ozone in smog. Thus, Dr. James E. Hansen introduced politics of CO2 & CH 4 as a function of developed vs developing countries like India. And yet, it would be appropriate here to mention that the eminent NASA scientist James Hansen, the man who could be called the father of global warming theory, admits that it was impossible to come up with reliable climate models because there is too much about the climate that scientists don’t understand. Thus, the entire global warming theory rests on the validity of trapping theory and so far no valid “one to one theory” was presented!!! . 5.3

Data Types

Historical documents contain a wealth of information about past climates. Observations of weather and climatic conditions can be found in ship and farmers’ logs, travelers’ diaries, newspaper accounts, and other written records. When properly evaluated, historical data can yield both qualitative and quantitative information about past climate. There are, also, several other ways that Scientists study how the Earth’s climate is changing: satellites, instrumental records, historical records and proxy data. Some scientists look to satellites to study the Earth’s changing climate. However, the satellite record is too short (around. 20 years) to provide much perspective on changing climate and yet they throw some light to interpret in right direction the ground based observations. Instrumental weather records: The record of instrumental weather measurements, extending back into the 19th century, provides data from thermometers, rain gauges, historical documents and other instruments. However, this record is too short to study many climatic processes. Also, because we have few instrumented observations from before the major industrial releases of carbon dioxide began, it is difficult to separate human and natural influences on climate. However, these records throw light on the short term natural rhythm in built in the nature, like cycles in precipitation that play an important role in agriculture and water resources availability. One must be careful while interpreting meteorological data as the change of units of measurements like inches to millimeters in rainfall; degrees Fahrenheit to degrees


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Celsius in temperature may lead to abrupt changes as the former are bigger units while later are smaller units. One inch is 2.5 cm or 25 mm. Palioclimatological weather records: Paleoclimatologists gather proxy data from natural recorders of climate variability such as tree rings, ice cores, fossil pollen, ocean sediments, corals and historical data. By analyzing records taken from these and other proxy sources, scientists can extend our understanding of climate far beyond the 100+ year instrumental record. Thus, Paleoclimatology is the study of climate prior to the widespread availability of records of temperature, precipitation and other instrumental meteorological data that can help to establish the range of natural climatic variability in a period prior to global scale human influence. If there is one thing that the paleoclimatic record shows, it is that the Earth’s climate is always changing. Climatic variability, including changes in the frequency of extreme events (like droughts, floods and storms), has always had a large impact on humans. For this reason, scientists study past climatic variability on various time scales to gain clues that will help society plan for future climate change. The study of paleoclimates have been particularly helpful in showing that the Earth’s climate system can shift between dramatically different climate states in a matter of years and/or decades. Understanding “climate surprises” of the past is critical if we are to avoid being surprised by abrupt climatic change. The study of past climate change also helps us understand how humans influence the Earth’s climate system. The paleoclimatic record also allows us to examine the causes of past climate change, and to help unravel how much of the present observed changes may be explained by natural causes, such as solar variability, and how much may be explained by human influences. Lastly, most state of the art climate prediction is accomplished using large sophisticated computer models of the climate system. A great deal of research has been focused on ensuring that these models can simulate most aspects of the modern, present-day, climate. It is also important to know how these same models simulate climate change. This can be accomplished by comparing simulations of past climate change with observations from paleoclimatic records. Thus, paleoclimatology helps us improve the ability of computer models to simulate future climate. Some of these are given as follows: Corals — Corals build their hard skeletons from calcium carbonate, a mineral extracted from seawater. The carbonate contains isotopes of oxygen, as well as trace metals, that can be used to determine the temperature of the water in which the coral grew. These temperature recordings can then be used to reconstruct climate when the coral lived. Fossil Pollen — All flowering plants produce pollen grains. Their distinctive shapes can be used to identify the type of plant from which they came. Since pollen grains are well preserved in the sediment layers in the bottom of a pond, lake or ocean, an analysis of the pollen grains in each layer tell us what kinds of plants were growing at the time the sediment was deposited. Inferences can then be made about the climate based on the types of plants found in each layer.


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Tree Rings — Since tree growth is influenced by climatic conditions, patterns in tree-ring widths, density, and isotopic composition reflect variations in climate.? In temperate regions where there is a distinct growing season, trees generally produce one ring a year, and thus record the climatic conditions of each year. Trees can grow to be hundreds to thousands of years old and can contain annually resolved records of climate for centuries to millennia. Ice Cores — Located high in mountains and in polar ice caps, ice has accumulated from snowfall over many millennia. Scientists drill through the deep ice to collect ice cores. These cores contain dust, air bubbles, or isotopes of oxygen that can be used to interpret the past climate of that area. Ocean & Lake Sediments — Billions of tons of sediment accumulate in the Ocean and the Lake basins each year. To interpret part climates, scientist drill cores of sediment from the basin floors of the Ocean and the Lake that include tiny fossils and chemicals. 5.4

Climate Change

Good weather records extend back less than 150 years in most places. In that time, the Earth’s global average temperature has increased by approximately 0.5 0C or 0.9 0F. Scientists are trying to determine how much of this warming is a natural fluctuation and how much is a result of human induced greenhouse warming. However, this tends to be confined to one parameter of weather, namely temperature as it plays vital role in the developed nations as they being located in extra-tropical zone. Since the end of the last ice age occurred over 10,000 years ago, the planet has continued to undergo changes in climate. Warming during medieval times and cooling during the “Little Ice Age” a few centuries ago dominate the last millennia. From paleoclimate records, we know that the climate of the past million years has been dominated by the glacial cycle, a pattern of ice ages and glacial retreats lasting thousands of years. The changes in ice cover over the Northern Hemisphere. Eighteen-thousand years ago, at the peak of the last ice age, scientists estimate that nearly 32% of the Earth’s land area was covered with ice, including much of Canada, Scandinavia, and the British Isles. These glaciers developed because the Earth was in the midst of an ice age. Today ice coverage about 10% of the Earth’s land surface. However, the literature review present that the “climate change” has two components, namely systematic variations that are in built in nature and the trend that is created by man’s action on nature. The systematic variations, known as cyclic variations, are ground-realities that are the outcome of interaction with known & unknown factors that are beyond the control of man. The trend is caused by several factors that are associated with man’s action on nature; and modern scientists are contemplating this to solely to global warming or rise in temperature. The recent unusual events are also attributed to global warming phenomena. As Indian economy is weather driven, it is essential that while making


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any inferences on weather & climate, this must be looked into in an integrated manner rather than in isolation. Up to around 1980s the studies on “climate change” were principally related to natural variations in climate and the impact of ecological changes on climate at local & regional level. The natural variations in the climate were studied using historical climate data, sediments, tree rings, etc along with solar phenomena like sunspot, solar flares, etc. Ecological changes primarily related to land-use changes and land cover such as de-forestation, changes in orography/topography, changes in human habitations & urbanization, agriculture, etc [Reddy & Jayanthi, 1974; Reddy & Rao, 1977; Reddy, 1984; Reddy, 1993; Reddy, 2000a; Reddy, 2007]. These were integrated with the dry-land agricultural planning in developing countries [Reddy, 1983-84, 1993, 2002a]. Now these are more or less masqued by the global warming concept primarily estimated using unsound mathematical models. Yet scientists started flooding the magazines with mind-boggling predictions on what happens to agriculture, health, sea level, etc [Raj Chengappa, 2002; Paul R. Epstein, 2000; McKenney & Rosenberg, 1993]. To provide a clear picture on climate change, the study of climate change is divided into two parts, namely natural variations that are in built in the nature that are beyond man’s control and the other, changes induced by man’s actions represented by trend, which are the creation by man. The natural variation part of climate change has irregular and systematic variations. Day-to-day, month-tomonth, year-to-year variations form part of irregular variations. The systematic variations part is dealt in Chapter 6. The man-induced variations also have two distinctive parts, namely ecological changes dealt in Chapter 7 and global warming, dealt in Chapter 8. The issues of unusual events vs global warming are dealt in Chapter 9.


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Chapter 6

Systematic Variations 6.1

Ancient Lore

The science of astrology started with the understanding of seasons and weather in relation to movement of extraterrestrial bodies known as planets; this understanding of ancient lore later became the science of astronomy, as a guide to fight wars, develop medicine to cure diseases, and practice agriculture, all of which were more seasonal. All, or most, cultures have developed a form of astrology such as Indian Astrology, Western Astrology, Chinese Astrology, Mexican Astrology, Celtic Astrology, etc. (Reddy, 2000b). The Western System is solar-based, the Chinese system is lunar-based, and the Indian system is luni-solar based. By the use of certain fixed stars, calendars were evolved to mark the movements of the Sun, the Moon, and the planets with reference to a point on the Earth. There was a category of priests trained to understand the lore of the divinatory calendars, which was one of the foundations of higher learning. One of the most fascinating and enchanting features about the practice of astrology is the fact that Indian astrologers, and the technique they use, often differ dramatically from town to town in India. However, there are no differences in the basic concept. They are the highly respected group in the society. It is a family tradition of astrological education. A lot of this ancient lore lost its glory with industrialization, as the family tradition in astrology lost its shine. In addition, the basic point around which astrological calculations are made also became erroneous. The principal activity was the time reckoning and the calendar computations in terms of the motion of the Sun, the Moon, and the planets along the zodiacal path with which were also associated 27 nakshtras. According to the ruling planet of a year, overall rainfall of that particular year should be anticipated as follows: Sun – moderate; Moon – very heavy; Mars – scanty; Mercury – good; Jupiter – very good; Venus – good; and Saturn – very low, etc. On every New Year day the respected gentlemen present what is in store in terms of weather, agriculture, expected political turmoils, disasters, etc. This ancient science of predicting rainfall talks about the wind direction. In northwest India the wind direction on Holi, the full-moon day of the last Hindu month Phalguna (approximately March) and wind direction on Akshayatrutiya, the third day of the month Vaisakha (approximately May) were used to predict whether the monsoon would be early or late (Reddy, 2005). Reddy (1977) observed a clear relationship between the onset of the monsoon over the Kerala Coast and the zonal component of wind at 50 mb level over Singapore (which presents a systematic variation with time), an equatorial station in the month of May. If the winds are westerly then the monsoon is early; if the winds are easterlies, the monsoon is late. The Chinese system of astrology has a 60-year cycle. This is based on a combination of five elements and twelve animal signs. In Indian astrology, the


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calendar system is the same as or similar to what is called the 60-year cycle [Prabhava (1987-88), Vibhava, — Krodhana, Akshaya (2046-47)] – the cycle of the Sun (6 years) and the Moon (10-years), i.e., 6 of 10 years; or the cycle of Jupiter – a cycle of five 12 years, similar to the Chinese 60-year cycle. The Indus Valley Civilization, which was before the Vedic period used the 60-year cycle. The Indian cycle is later by 3 years than the Chinese cycle. In both Indian and Chinese astrology, the 60-year cycle is more in relation to the Moon/nakshatras. Similar to this, the All-India Southwest Monsoon rainfall also presents a 60-year cycle. This rainfall cycle lags by 3 years to Indian astrological cycle. The present 60-year cycle in Chinese astrological cycle started in 1984-85 will continue upto 2043-44; in Indian astrological cycle started in 1987-88 will continue upto 2046-47 and in the All-India Southwest Monsoon rainfall started in 1990-91 will continue upto 204950. The Aztecs noted that 5 Venus years equal to 8 Sun years. These cycles only repeated after 65 Sun and 104 Venus years, i.e., once in 520 years. The number 104 is the longest period in Mexican time keeping, and was called one “old age”. The Mexican “Century” was 52 years. Similar to this, the rainfall data of Fortaleza in Brazil in Southern Hemisphere presents a 52-year cycle as well the onset of monsoon over Kerala Coast in India in the Northern Hemisphere around the same latitude belt. 6.2

Sun-Weather Relationship

King (1975) presented an important review of the scientific articles on the Sun-Weather relationship appeared in the literature up to that time. He states “As they profoundly influence civilization, and have not been well explored, Sun-Weather relationships should become a major field of research in the decades being ushered in by GARP and IMS”. He also further states, “Many people have suggested in the past that the weather is influenced by the 11- and 22-year (double sunspot cycle) sunspot cycles” — Figure 6a presents 400 years of sunspot observations (bottom) and solar cycle variations during 1975 to 2005 (top). He further says that “I believe that the accumulated evidence is so compelling that is no longer possible to deny the existence of strong connections between the weather and radiation changes (electromagnetic and/or corpuscular) associated with a whole range of solar phenomena. Even the most skeptical scientist who investigates the literature thoroughly will be forced to concede that important aspects of lower-atmospheric behavior are associated with solar phenomena ranging from short-lived events such as solar flares, through 27-day solar rotations to the 11-year, 22-year, and even longer solar cycles”. Sunspot Cycles: King (1975) presents that Xanthakis in 1973 observed (Figure 6b) at higher latitudes in Northern Hemisphere (70-80 degrees) the 11-year solar cycle was positively correlated with 10-cm oscillation in the annual rainfall analysis total; between 60-70 degrees they are negatively correlated and at lower latitudes (50-60 degrees) a negative correlation existed before about 1915 and a positive correlation after that. The three zones respectively based on 12, 22 & 36 stations


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data. Brown in 1974 observed opposite pattern at 17 degrees and 43 degrees in Southern Hemisphere in the rainfall oscillations associated with the 11-year sunspot cycle (Figure 6c). The curves were obtained by applying an 8-15 year filter to the annual differences. King in 1973 also observed opposite ways at 55 and 35 degrees in the Northern Hemisphere. Scientists noticed that the 11-year sunspot cycle is not fixed but vary between 9 to 13 years. The solar-cycle-induced rainfall oscillations referred to range from about 3 to some 50% of the normal annual total. Obviously, a reduction of rainfall by 25% in each of several years around one of the extremes of the sunspot cycle is of considerable importance. Analyses combining data from zones exhibiting opposite solar cycle effects will invariably lead to the erroneous conclusion that no solar cycle effect exists, as well as an analysis of rainfall data from regions situated between zones in which the sunspot cycle effect is opposite. Such variations with latitude are quite obvious as the climate systems differ. The annual rainfall totals at Fortaleza, Brazil by Markham in 1974 (Figure 6 d) and at three sites in South Africa by Tyson in 1974 (Figure 6e) were positively correlated with the “double” sunspot cycle for considerable periods of time. Both these are from Southern Hemisphere. The modulation associated with the double


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cycle amounted to about 35% of the average annual total at Fortaleza and at about 25% of the average rainfall at the South African stations. The data from Fortaleza are available from 1865 onwards. After the first 60 years the relationship between the rainfall and the double cycle at Fortaleza changed phase. The 50 years of data available from South Africa show a consistent positive correlation with the double cycle. According to Tyson & his co-authors in 1974 the African rainfall data for latitudes south of those where the double sunspot cycle influence is observed exhibit a pronounced oscillation having a period of about 10 years in anti-phase with the sunspot cycle as noted by King & his co-authors in 1974. Cornish in 1936 & 1954 and Whippe in 1936 in Adelaide, Australia observed impressive evidence of an association between rainfall and double sunspot cycle (Figure 6f). Cornish in 1954 concluded that this oscillation must be due to secular changes in the latitudinal paths of anticyclones with their attendant cyclones across southern Australia. Bodurtha in 1952 reported that the sunspot cycle


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strongly influences both the frequency and the intensity of anticyclogenesis, so it may be concluded that the number and intensity of anticyclones and the latitudes at which they occur all vary during the solar cycle. King & his co-authors presented another striking illustration of the influence of the double sunspot cycle on the weather in 1974 (Figure 6g). The July temperature in central England during the period 1750-1880 exhibited an oscillation of nearly 1 oC in phase with double sunspot cycle. The temperature curve is somewhat anomalous during the years 1840-1855 when the temperature extremes occurred around sunspot minima instead of near sunspot maximum. Brooks in 1951 presents that it appears to be firmly established is that over the world as a whole, and especially in the tropical regions, the mean air temperature at the Earth’s surface varies in opposition to the sunspot cycle, being the lowest at sunspot minima. The double sunspot cycle appears to influence the climate of the United States in several ways. Thomson in 1973 and Roberts in 1974 have shown that droughts in various parts of the country occur around every second sunspot minima. Newman in 1965 has shown that winter temperatures in Boston exhibit a 22-year periodicity. Thompson in 1973 reported a remarkable correlation between the July/August temperature in the corn belt of United States and the double sunspot cycle. Mather in 1974 presented striking evidence between double sunspot cycle and temperature in the US. Willett in 1961 discussed the possible relationship between the weather and the 80-year sunspot cycle. A sunspot cycle induced meteorological variation may suddenly reverse phase (Figure 6b). King presented two such examples. Brooks in 1951 observed in his reviews of the relationships between solar and meteorological phenomena that over the world as a whole and especially in the tropical regions, the mean air temperature at the Earth’s surface varies in opposition to the sunspot cycle, being lowest at sunspot maxima and highest at sunspot minima. This was suspected by Hershel as early as 1801 but was first clearly demonstrated by Koppen in 1873 and has since been confirmed by Mieke in 1913, Hildebrandson in 1914, Walker in 1915 & 1923, Mecking in 1918, Clayton in 1923, Droste in 1924 and others. In their Handbook of Statistical Methods in Meteorology, Brooks & Carruthers in 1953 examined the significance of some of the negative correlations between tropical temperatures and sunspot numbers and concluded that they were undoubtedly significant. Although the tropical temperatures examined by the early workers referred to by Brooks correlated negatively with sunspot number, Troup in 1962 pointed out a relatively recent reversal of this “Over the tropics as a whole, the correlations between sunspot number and tropical temperatures which were negative prior to 1920 have become zero or even positive subsequently. Of recent years there has apparently been a reversal in the phase of the temperature cycle”. The level of the water in Lake Victoria, positively correlated with sunspot number before about 1930, has been negatively correlated since about 1950;


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during the interim period little correlation existed between sunspot number and the water level. Stringfellow in 1974 observed a good relationship between Fiveyear means of the Annual Lightning events index in Great Britain and sunspot cycle (Figure 6h). Brooks in 1934 first showed that a significant relationship exists between the occurrence of thunderstorms and the annual sunspot numbers: correlation coefficients up to 0.91 were obtained from long series of data, the largest correlation coefficients relating to high latitudes. In 1953 Brooks and Carruthers made this observation: ”There is a correlation coefficient of +0.88 between the number of thunderstorms recorded in Siberia and mean annual sunspot relative number. Since it is inconceivable that thunderstorms in Siberia cause sunspots, it is reasonable to assume that sunspots or some other solar phenomenon associated with sunspots cause thunderstorms”. They also established statistically that the observed variation of the frequency of thunderstorms in the West Indies during the sunspot cycle was definitely significant, the probability of obtaining the correlation by chance being less than 0.1% “We have established”, they said, “a high probability that thunderstorm frequency in the West Indies is related in some way to the sunspot maximum”. Schostakowitsch made one of the most comprehensive investigations of the influence of the solar cycle on the weather. He prepared detailed global maps (reproduced by Clayton in 1933) showing how the temperature, pressure and rainfall over the Earth vary between sunspot minimum and maximum. Reddy & Lahori (1977) subjected to power spectrum & harmonic analysis the monthly mean data


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of dynamic height of constant pressure surface, temperature and eastward & northward velocities of wind at 100, 50 & 30 mb levels from eleven equatorial stations in the latitude belt of 13.5 degrees north latitude to 12.0 degrees south latitudes. It was noted the quasi-biennial Oscillation (QBO) the 5th harmonic of sunspot 11-year cycle is acting in unison with the multiple mode of annual cycle, where higher modes are prominent at low sunspot activity and lower modes at higher sunspot activity. That is near the maximum sunspot activity the QBO is 1024 months and near the minimum sunspot activity the period of QBO is 30-36 months. This type of variation may be attributed to the modulating effect of annual cycle, where the amplitude of annual cycle is maximal. Reddy et al. (1977) subjected the monthly mean data for 44 to 67 years at 20 stations of total solar radiation and net radiation intensities estimated using simple models (see Chapter 3) to power spectrum analysis. The results presented significant influence of sunspot cycle on total solar radiation and net radiation intensities. Solar flares: Several analyses have indicated that short-lived solar phenomena, such as solar flares, magnetic field, etc, may trigger a response in the lower atmosphere. Schuurmans in 1965 studied the tropospheric response to solar flares using the change in height of the 500-mb level over much of the Northern Hemisphere during the first 24 hour after each of 53 flares. He concluded that the pattern of height changes “shows a remarkable regularity with a symmetry with respect to the geomagnetic rather than to the geographic pole”. Results such as these show that the circulation of the lower atmosphere is significantly modified after solar flares. Reddy & Rao (1977) studied the effect of solar flares on lower tropospheric (i.e. ground surface, 850, 700 and 500 mb levels) temperature and pressure (i.e. dynamic height of constant pressure surface) using 81 flares for the period 195759 at few selected locations in India. The analysis showed that the effect of solar flare occurs within 24-hr period, while the influence starts receding after 48-hr. The change in magnitude of the flare influence is observed to decrease with decreasing of altitude. The effect on pressure is more pronounced compared to that on temperature. As the change in the magnitude of the solar flare influence is seen to depend on the intensity of the flare but not on the time of occurrence of the flare. The same type of seasonal variation (i.e. winter maximum and summer minimum) was not seen at all the stations, but this variation shows a considerable relation to the general circulation pattern prevailing at that time over the region – low & high pressure belts. That is, the authors noted significant influence of solar flares on lower tropospheric weather in association with prevailing synoptic weather conditions. Solar phenomena tend to recur with periods of the order of 27 days, the synodic period of revolution of the Sun. Panofsky in 1967 has shown that this period is close to the period of the maximum fluctuations of mean west winds at upper-middle latitudes. Similar behaviour is not observed at lower latitudes. After an investigation of the 500-mb circulation along the auroral belt, Riehl in 1956 concluded that circulation increases and decreases take place with a period which


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can be related to the mean solar rotation in the equatorial zone. Rosenberg and Coleman in 1974 studied the southern California rainfall power spectrum and concluded that there is a significant peak at almost exactly 27 days. Baerkes in 1955 has reported the existence of a 27-day periodicity in wind speed and Egyed in 1961 noted a 27-day periodicity in soil temperature. Rao & Reddy (1972 a & b) and Reddy (1974a) studies on surface winds & rainfall at few Indian stations present significant solar and lunar influence. We are well aware the sea/ocean tides vary with phases of the Moon. Magnetic field: Many authors including Sazonov in 1965, Mustel in 1966, Baynon and Winstanley in 1969, Roberts and Olson in 1973, Stolov and Shapiro in 1974, and Sidorenkov in 1974 have reported that Earth’s magnetic field may play a role in bringing some sun-weather relationships (Figures 6i presented by Wollin and co-authors in 1973 & Wales-Smith in 1973). Figure 6j presented by Wollin and co-authors in 1974, for example, shows oxygen-isotope data, which provide a measure of temperature and magnetic intensity values obtained from a single deep-sea core formed during a 500,000-year period. Cold epochs occurred when the magnetic intensity was relatively high and vice versa. King and Willis in 1974 have suggested that the “Little Ice Age” which occurred in Europe between 1550

and 1850 (Figure 6k) was associated with the unusually high values of magnetic inclination that existed at that time. Milankovitch Cycles in Paleoclimate: Milankovich cycles are cycles in the Earth’s orbit that influence the amount of solar radiation striking different parts of the Earth at different times of year. They are named after a Serbian mathematician, Milutin Milankovitch, who explained how these orbital cycles cause the advance


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and retreat of the polar ice caps. Although they are named after Milankovitch, he was not the first to link orbital cycles to climate. Adhemar in 1842 and Croll in1875 were two of the earliest. Ozone: The total ozone content of the atmosphere also varies during the sunspot cycle and possibly during the short-lived solar events. Various authors, including Willet and Prohaska in 1965, Christie in 1973 and Paetzold in 1973 have described variations of ozone content that occurred during the sunspot cycle while Dobson and his co-authors in 1929 said “there is a small but definite tendency for days with much ozone to be associated with magnetically disturbed conditions”. Weeks and co-authors in 1972 concluded that the ozone content is reduced during strong solar proton events. Prior to 1980 the Sun-Weather relationship was an important topic for research and achieved significant results by scientists from the globe. Once after the papers linking global temperature increases to greenhouse gases, the entire focus of research changed and as a result the research priorities completely changed and sun-weather-climate change aspects have gone in to oblivion. There is an urgent need to re-look into these aspects and separate and thus the integrated effect of the Sun on the short & long-term variations in weather-climate system. 6.3

Systematic Variations in Observed Data

In this section the Sun-Weather component was not linked but presented studies on the possible patterns in observed historical precipitation data over different parts of the globe, known as systematic variations / climatic cycles / climatic fluctuations. Climatic fluctuations have profound effects on water resources. In


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arid and semi-arid zones, climatic fluctuations affect many hydrological characteristics of watersheds including quantity of base flow, the occurrence of large floods. The importance of climatic fluctuations in agriculture was dealt by Reddy (1993) with reference to several countries around the globe. The literature is rich with studies on climatic fluctuations. The author presented in brief the results of the climatic fluctuations from his studies. Climates in the savanna of northern Africa have changed substantially over the past few millennia (Jackson, 1957). Climatic changes over the shorter periods have been identified in other parts of the world (Lamb, 1972). Trends of both increasing and decreasing rainfall have been found in some places in the tropics. Fluctuations that are repeated in time have been detected for some places in the tropics (Dyer, 1977; Parthasarathy & Mooley, 1978). Dyer (1977) predicted that the next period of drought in South Africa should occur in the middle of 1980. In such situations the average climate discussed in Chapter 4 give misleading signal to planners. The climate presented in Chapter 4 when discussed by taking into account the trends & fluctuations provide the realistic conditions for better planning. Lockwood (2001) presented a review of papers on climatic changes and oscillations. Webb, et al. (2005) presented time series plot of the annual flow volume for the Colorado River at Lee’s Ferry along with linear trend line. However, without looking at abrupt change, fitting the data to linear curve give a misleading conclusions and thus loose faith on such trend. For example, the fluctuations from 1890 – 1930 showed a sudden drop and from around 1930 to 2000 presented different fluctuations. There is a need to correct this sudden drop and that make the results meaningful. This is an important issue while studying the observed data series that may give spurious results. Also, it is important to take into account the changes in units of measurements or place of observation, etc. In recent years, in majority of developing countries the meteorological observatories are in dilapidated condition. Models: World Meteorological Organization (WMO) issued a Technical Note (No. 79) as back as 1966 on the subject “climate change”. One of the components of this report is the assessment of climatic fluctuations in the observed meteorological data series, known as systematic variations, principally in the precipitation data. The time series contain not only systematic variations of different periods and trend and irregular variations. Using the methods presented in the technical report it is possible to separate these factors and their significance. However, the accuracy primarily depends upon the length of the data series. The data series must be for a period at least double to the systematic variation expected to be present in the data. That is, if we expect a 60-year cycle, we need minimum of 120 years data series. Such data series are available only at few selected locations. For India, Parthasarathy, et al. (1995) presented precipitation data series at monthly, seasonal and annual for the period 1871 to 1994 for All-India, five homogeneous regions and 29 meteorological sub-divisions on the basis of a fixed and well-distributed network of 306 rain-gauge stations by proper area-weightage. Similarly, all over the world such data series were presented by respective meteorological services /


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researchers. Figure 6l presents standardized time series of rainfall anomalies for the twentieth century (top) and a century period of the GFDL model simulation containing the most prominent dry episode (bottom). Climate change traditionally refers to those present in the climate itself, known as natural changes, known as Natural Rhythm. The natural changes are beyond man’s control. The natural variations have two components, namely irregular variations and systematic variations. Irregular variations vary with time – day-today, season-to-season, year-to-year, etc. The systematic variations are also known as “climatic cycles” or natural rhythm or fluctuations. This part of the climate is generally referred to as “climate change”. Climatic cycles in annual or seasonal rainfall means, it shows above the average pattern for some continuous years followed by about the same number of years of below the average rainfall pattern and this repeats itself with the time as was the case with astrological cycles and sunspot cycle. In temperature we call such cycles of longer duration as ice ages, etc. Where such cycles are present the “normals” have no meaning. However, the series are affected by localized disturbances like wars or man induced ecological changes that are known as trend.


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WMO (1966) presented details on the method of estimating the systematic variations or cycles (amplitude & angle) in precipitation data. Blackman & Tukey (1958) power spectrum analysis, Moving average technique, Iterative auto-regression technique, Sine curves matching technique, etc. For power spectrum analysis, the primary data needed for the study are the continuous long series annual or seasonal data at least twice the length of the expected long cycle. This technique was widely used in the estimation of cycles in precipitation data. Some of these procedures could also be used in the case of temperature to deduce the shorter cycles. In the case of temperature, the concept of ice ages is deduced through the paleoclimatological tools. Results: Using the moving average technique, Reddy (1977) observed 52-year cycle in the dates of onset of Southwest Monsoon observed data over Kerala Coast in India. This is given in Figure 6m. The average date is 1st June. The top figure presents the association of lower stratospheric 50 mb winds over Singapore in relation to onset on monsoon in India. When the winds were easterlies at 50 mb in the month of May, the onset will be late in that year and when the winds are westerlies the onset will be early in that year. The winds at 50 mb level over Singapore are very systematic. In the case of westerly regime, it is always – 12


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months and 24 months and the easterly regime, it is always 12 months and 6 months. This pattern makes it easy to predict the onset date over Kerala Coast in advance. This was presented in the figure by dotted lines and found to be correct. In fact, Reddy made the study using the data of 100, 50 & mb levels wind at Singapore, Bogota, Malakal and Lima but found that the onset dates are following the 50 mb winds over Singapore only and the wind at other locations including 100 mb winds at Singapore haven’t presented any relation with the dates of onset. Kane (1995) used different data sets (a) derived data sets of onset dates of Southwest Monsoon over Kerala Coast and (b) average 50 mb winds of Balboa, Singapore and Gam and did not found relationship as was observed by the author with the data other than Singapore. That is, it is important to follow trial & error approach to get a better match. Using the power spectrum analysis Reddy (1984) tried to homogenize the climate of northeast Brazil. In this study used 70-years annual precipitation data series of 105 stations. Based on the results the study zone is divided into three groups, namely zones less than 4 degrees south latitude, between 4 to 8 degrees and more than 8 degrees. In all the three zones harmonics 0, 1 and 2 are significant at many locations. Harmonics 4 & 5, 9-12 and 13-15 are significant at many stations in the first two zones. The harmonic 16-25 (QBO) is mainly significant in the last zone. The auto-regression analysis of 133-year data series (1849-1981) of Fortaleza in the first zone revealed four significant cycles, namely 52-year cycle along with sub-multiples, namely 26, 13 and 6.5 years. The first three cycles are closer to harmonics 1, 2 and 4, while the 4th cycle is not significantly seen in the spectrum analysis, which is slightly different from harmonic 9-12. Through the iterative regression analysis the amplitudes and phase angles for the four cycles were derived (Table 6). Table 6: Estimated amplitudes and phase angles of four cycles in Fortaleza rainfall data series Cycle (years)

Amplitude

Angle (degrees)

52.0

0.1875

6.923

26.0

0.3125

318.462

13.0

0.3125

110.769

6.5

0.1875

0.000

Note: Normalized amplitude presents the deviations from the average as a ratio of average; the phase angle corresponds to 1911 at Fortaleza. It is seen from the table that the amplitudes of cycles 26 & 13 years are higher than those of 52 and 6.5 years cycles. Strang in 1979 reported a 13-year cycle; Girardi in 1983 reported 26-year cycle; Carlos and co-authors in 1982 found cycles 26 and 13 years as significant. However, they stated that these two cycles explained only 24% of variance in the data series. The 52 year cycle found in onset dates over a low latitude Kerala Coast in India on the Northern Hemisphere lags behind the 52 year cycle observed in Fortaleza rainfall data series at lower latitude in Southern Hemisphere.


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The integrated pattern along with observed data series of Fortaleza is presented in Figure 6n(bottom curve), in which the observed and predicted patterns present a perfect match. This pattern is also seen in the first two zones. The matching is poor in the last zone. Few locations present good agreement between


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observed and predicted curves prior to 1920’s and later 1955’s. There is discrepancy during 1920-1955. Similar to Fortaleza pattern is also evident in the precipitation average of 12 locations in Rio Grande do Norte [top curve — right) while top curve — left depicts the rainfall pattern of two groups of locations in Piaui region in which during 1920-1955 the two groups presented opposite behavior. Using similar analysis (Reddy & Singh, 1981) of the annual rainfall data of Mahalapye in Botswana observed 60-year cycle with sub-multiples of 30, 20 & 10 years. The integrated estimate along with the observed time series is presented in Figure 6o. Reddy (1986) studied the precipitation data series of 16 stations in Mozambique in Southern Hemisphere. In this analysis also included one station each from Malawi (Chileka) & Zimbabwe (Salisbury) and Lilongwe. The analysis was carried out using iterative regression approach. The annual rainfall time series of Catuane (southern most point in Mozambique) presented a 54-year cycle along with a sub-multiple of 18-year cycle. The integrated pattern along with the observed time series is presented in Figure 6p. Table 7 presents estimated amplitude and phase angles. Similar pattern is observed in majority of the stations. However they present coast to inland & latitude change in the starting year of the integrated


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cycle. At the same latitude the starting year is early in coastal stations compared to inland stations and early in lower latitudes. Nampula, Mutuali, Ulongoe & Chileka, Lylongwe around the same latitude zone present 40-year cycle with the starting year respectively showing sharp delay. That is at Nampula it started in 1973 and at Lylongwe it started in 2004. This is longitudinal variation. Table 7: Estimated amplitudes and phase angles of Durban & Catuane rainfall data series Catuane Cycle (years)

Durban Amplitude (mm)

Phase angle

Cycle (years)

Amplitude (mm)

(degrees)

Phase angle (degrees)

54

200

86.7

66

250

185.5

18

200

100.0

22

350

180.0

Reddy & Mersha (1990) analyzed the annual precipitation data of Ethiopia in Northern Hemisphere. Annual rainfall data was available at 18 locations for more than 25 years in Ethiopia. Only at three stations the series are for more than 50 years. The 18 stations data series were subjected to iterative regression approach – sine curve fitting. The results are grouped under 8 types. The longest cycle of 54 years was noted in Koka data series located at a latitude of 8025’ North and the shortest of 22 years was noted at Asmara at a latitude 150 17’ North while at Addis Ababa and Massawa with longest series presented irregular pattern. It was noted that in general the low-lying areas have a shorter periodicity compared to


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elevated areas. Mayole at 30 31’ North latitude presented 40-year cycle, similar to that seen in Mozambique data in the Southern Hemisphere. At seven stations in between 7.5 to 11.0 degrees North present 36 year cycle. However, there are differences in the starting years of above average pattern. Four locations presented 28-year cycle. Figure 6q presents these patterns for four locations, namely In the case of Gore & Jijiga the prominent cycles are 36 & 28-years; for Mayole & Asmara [now it is in Eritria] they are 40 & 22-years. Tyson (1978) studied the Durban in South Africa annual rainfall data and noted 66 and 22-year cycles. Table 7 presents the amplitude and phase angles of the cycles noted in Durban along with Catuane rainfall series. Reddy (2000a) studied the All-India Southwest Monsoon Rainfall series and the rainfall series for three meteorological sub-divisions in Andhra Pradesh using the data series presented by Parthasarathy, et al. (1995) for the period 1871 to 1994. The All-India Southwest Monsoon Rainfall series presented a 60-year cycle (Figure 6s) — The bottom diagram refers to annual march of rainfall and the top diagram refers to the march of 10-year rainfall totals. In the above the average 30year part of the cycle present deficit rainfall (i.e., less than 90% of average) in 2 to 3 years while the same during the below the average 30-year part of the cycle are 6 to 10 years. The current ongoing above the average cycle commenced during 1991 is predicted to continue upto 2020. So far the rainfall was normal or above normal. The agroclimatic variable (G = available effective rainy period, weeks; S = starting week number of planting rains – starting time of G] time series of Kurnool in Andhra Pradesh presented a 54-year cycle. Using this pattern the rainfall data series of the three meteorological sub-divisions in Andhra Pradesh were analyzed and found they follow this pattern in the case of Southwest Monsoon (SWM) rainfall data series and a reverse pattern in the case of Northeast Monsoon (NEM) rainfall data series [Figure 6t]. The bottom diagram refers to the SWM & NEM cyclic pattern in which given the % number of years the rainfall of the individual years are less than the average in each 28-year period. The top diagram presents the pattern of agroclimatic variables (G & S) pattern of Kurnool. The 54 and its’ sub-multiple like 28 years cycle are also present in the Mozambique & Ethiopia precipitation data series. These results clearly demonstrate one thing that the precipitation data follow rhythmic patterns in terms of cycles & their sub-multiples. It appears in certain conditions all these are clearly seen but under certain other conditions either cycle or its’ sub-multiple is clearly seen. These fluctuations are observed in both the Southern & the Northern Hemisphere precipitation data series. 66-years cycle is the longest cycle observed at higher latitude zone and 22-years cycle is the shortest cycle observed at lower latitude zone. In between, the important cycles observed are 60, 56,54, 52, 40, 36, 28-years cycles. By using the data accumulated in the last three decades, these results could be updated and could be integrated in terms of latitude-longitude; land-sea; sun-weather. We must look this in terms of global weather patterns – summer rains, winter rains, summer & winter rains (bi-


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model rainfall) — but not in isolation and then only we can achieve reasonably good conclusions that help planning in any country or region.


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Chapter 7

Ecological Change 7.1

What is Ecological Change?

In addition to changes in the atmosphere’s composition, changes in the land surface & cover, known as ecological changes, can have important effects on climate. For example, a change in land use and cover can affect temperature by changing how much solar radiation the land reflects and absorbs. Processes such as deforestation, reforestation, desertification, changes in topography/orography, urbanization, agriculture – dry-land to wet-land & vice versa or grazing lands, water resources – construction of dams, etc contribute to changes in temperature, wind, precipitation, etc in places they occur. Changes in land cover and land use can also affect the amount of carbon dioxide and other greenhouse gases taken up or released by the land surface and can have significant effects on radiative forcings and thus the climate at the local & regional level by changing the reflectivity of land surface known as albedo factor, formation of thermal inversions, etc. To understand global land-cover change as an element of global environmental change, it will be necessary to specify the links between human systems generating changes both in land use and in the physical systems that are affected by the resulting changes in land covers. The environmental consequences of uses of land cover (changes in the state of cover) affect the original driving forces through the environmental impacts feedback loop. Likewise these land-cover changes can be repeated elsewhere such that they reach a global magnitude that trigger climate change, which in turn feeds back on the local physical system, affecting land cover and ultimately the driving forces through the environmental impact loop. Regardless of the stimuli - local or global environmental impacts or the interactions of driving forces in their social context - changes in driving forces at any given time may trigger a new land use, with new consequences for the land-use/cover system. This perspective indicates that understanding of global environmental change must consider the conditions and changes in land cover engendered by changes in land use; the rates of change in the conversion-modification-maintenance processes of use; and the human forces and societal conditions that influence the kinds and rates of the processes. Land use is obviously constrained by environmental factors such as soil characteristics, climate, topography, and vegetation. But it also reflects the importance of land as a key and finite resource for most human activities including agriculture, industry, roads including railways, forestry, energy production, settlement, recreation, and water catchment and storage. Land is a fundamental factor of production, and through much of the course of human history, it has been tightly coupled to economic growth. As a result, control over land and its use is often an object of intense human interactions.


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Human activities that make use of, and hence change or maintain, attribute of land cover are considered to be the proximate sources of change. They range from the initial conversion of natural forest into cropland to on-going grassland management (e.g., determining the intensity of grazing and fire frequency). Such actions arise as a consequence of a very wide range of social objectives, including the need for food, fibre, living space, and recreation; they therefore cannot be understood independent of the underlying driving forces that motivate and constrain production and consumption. Some of these, such as property rights and the structures of power from the local to the international level, influence access to or control over land resources. Others, such as population density and the level of economic and social development, affect the demands that will be placed on the land, while technology influences the intensity of exploitation that is possible. Still others, such as agricultural pricing policies, shape land-use decisions by creating the incentives that motivate individual decision makers. Interpretations of how these factors interact to produce different uses of the land in different environmental, historical, and social contexts are controversial in both policymaking and scholarly settings. Furthermore, there are many theories regarding which factors are the most important determinants. Particular controversy arises in assessing the relative importance of the different forces underlying land-use decisions in specific cases. For example, apparent dryland degradation could be the result of: overgrazing by increasingly numerous groups of nomadic cattle herders; an unintended consequence of a “development” intervention such as the drilling of bore holes which increases stress on land close to the wells; or the political clout of groups that, through governmental connections, are able to over-exploit land belonging to the state or local communities. Identifying a particular cause may have implications for the rights of competing user groups or the formulation of policy responses. There are several possible forces driving land-use and land-cover changes. In other words it relates to population & their lifestyle. Population density found to be related to agricultural expansion and intensification everywhere, but only in some regions to deforestation. The interactions of population, affluence, and technology as causes of environmental change have been explored extensively, but research on the direct association of affluence or technology with land use change is not as common. This is because of the paucity of globally comparative data for statistical assessments and because of the common assumption that level of affluence or technology do not by themselves govern human-environment relationships but must be considered within a larger set of contextual variables. Nonetheless, some historical assessments associate high levels of affluence and industrial development (and thus the ability to draw resources from elsewhere) with the return of forest cover. Global comparisons indicate that afforestation is largely a phenomenon of advanced industrial societies, which are both affluent and have high technological capacity. Wealth, however, also increases per capita consumption, bringing about environmental change through higher resource demands, although these higher


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demands can be reduced by advanced technologies available to wealthy societies. Poverty is often associated with environmental degradation, although recent research shows that this relationship is strongly influenced by other factors as well. These mixed conclusions indicate the importance of further studies of the relationship between level of affluence and environmental change. It is obvious that technological development alters the usefulness and demand for different natural resources. The extension of basic transport infrastructure such as roads, railways, and airports, can open up previously inaccessible resources and lead to their exploitation and degradation. To these added further (i) political economy, which includes the systems of exchange, ownership, and control; (ii) political structure, involving the institutions and organization of governance; and (iii) attitudes and values of individuals and groups. Changes in attitudes and values may add a dimension to environmental change that cannot be explained otherwise, such as impact on land use of the “green” movement. Improved transport facilities are expected to exacerbate land degradation if the region in question is small, but its impact on larger regions will vary by circumstance. Additional comparative studies are needed to address the interactions of different driving forces with their environmental context. However, the specific role of any of the proposed driving forces is extremely difficult to demonstrate at this global scale of analysis, however, because of their complex interrelationships, and interactions with other factors such as social organization, attitudes, and values, which have also undergone profound changes. As a result, research is driven by subjective interpretations and assumptions rather than by attempts to test different hypotheses at global level. Most of the components have direct and indirect impacts on climate related changes. In some cases the indirect effects more dangerous over the direct impacts. Though the individual components impact is felt globally, the impact at local, regional and national level they are large. Certain components may be significantly felt in some countries and few others in other countries. Because of this, the impact of ecological changes on climate made complex. 7.2

Population & Lifestyle related Changes

Let us look at changes in population & lifestyle with an example of US [from a publication of Population Reference Bureau, 2006 – Lifestyle choices affect US, impact on the Environment, by Sandra Yin —]. Between 1950 and 2005, US population nearly doubled and in many cases, the consumption of resources is more than doubled. For example, (a) overall energy consumption nearly tripled. Petroleum consumption within the transportation sector rose more than 300% between 1950 and 2005; (b) Wood consumption was up by 171% between 1950 and 2002; (c) Coal consumption increased by 128% from 1950 to 2005; and (d) Water use was up by 127% between 1950 and 2000. The US population reaching 300 million might not be seen relevant at a global level. After all, the US represents just 5% of the world population. But it consumes disproportionately larger amounts than any other nation in the world – at least one-quarter of practically every natural resource, because of its’ lifestyle choice. The high consumption tends to occur in households in the highest income quintiles. For example, households in


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the top-income bracket own on an average 2.8 vehicles and this number progressively drops in lower household-income groups. That is, how we live spatially affects other consumption patterns. In recent decades, “sprawl” has become the most common-land use pattern that refers to low-density residential-subdivisions, commercial strips, large retail complexes surrounded by acres of parking and office parks far from home and shops, and a growing network of roads to link them. This is probably the most consumptive housing pattern. Sprawl translates into longer drive to connect home with work, school, and recreation. Not surprisingly, US’s annual number of vehicle miles traveled in 2004 was nearly 6.5 times the number in 1950. As dependency on cars grows, fuel consumption rises exponentially and more stop-and-go driving results in less fuel efficiency and more pollution. The share of workers who drove top work alone rose from 64% to 76% between 1980 and 2000. During that same period, the share that carpool fell from 20% to 12%. The US has fewer people than India & China, but motor vehicles per 1000 are more common in US (Table 8). Table 8: Estimated number of vehicles vs population Country

P

N

Estimated No. of motor vehicles

India

1.122

9

10,098,000

China

1.311

12

15,732,000

US

0.300

779

233,700,000

Note: P = Population in 2006 in billions; N = No. of motor vehicles per 1000 people. Even as US passes the 300-million mark, American’s use 75% more water per capita than the average person in the world’s developed nations [US with 1682 cubic meters of water per person; 956 for developed countries & 545 for developing countries). This tendency is clearly evident in developing countries too in addition to developed countries. 7.3

Forest Related Land Use Changes

Forests cover about 30% of the global total land area; this amounts to just under 40 million km2, but it is unevenly distributed. Deforestation, mainly conversion of forests to agricultural land, is continuing at an alarmingly high rate. Forest area decreased worldwide by 0.22% per year in the period 1990-2000 and 0.18% per year between 2000 and 2005. However, the net loss of forest is slowing down as a result of the planting of new forests and of natural expansion of forests. Primary forests account for over a third of global forest area, but 60 000 km2 (an area roughly the size of Ireland) continue to be lost or modified by logging or other human interventions each year. Forest plantations are increasing but make up less than 5% of overall forest area. The remainder are mainly modified natural forests, but also semi-natural forests.


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The world’s natural forests are experiencing land use change due to both direct and indirect causes. Direct causes include immediate human land use activities that change forest cover in a local area. Key drivers include agricultural expansion, infrastructure development, wood extraction, climate change, fire and alien invasive species. Underlying causes result from social and institutional processes that may indirectly impact forest cover from a local, national, or international level. Prominent underlying causes include market failure and perverse incentives, corruption, inappropriate state policies and institutional failure, population pressure and poverty. The most significant human-related, direct causes affecting forest cover are discussed below. Agricultural expansion: Over the years, researchers have identified agricultural expansion as a major factor in almost all studies on deforestation. In the 1990s, according to the United Nations Environment Programme (UNEP), 70% of total deforested areas were converted to permanent agriculture systems. Despite the compelling figure, regional differences should be noted. For example, in Latin America conversion to agriculture has been large scale and permanent whereas in Africa small-scale agricultural enterprises have predominated. In Asia, the changes have been more equally distributed between permanent agriculture and areas under shifting cultivation. Historically, increases in food production have been at the expense of millions of hectares of forest. Humans have always cleared land for agriculture either for subsistence or for larger scale settling and planting. The FAO claims that former is less a threat to forests than the latter. Infrastructure development: The conversion of forestland to infrastructure development can take several forms, including road-building, hydroelectric dam construction, etc. Road construction reduces forest cover both directly by occupying land, and indirectly, by fragmenting the landscape and opening it up for exploitation. A study showed that 86% of Amazonian forests lost between 1991 and 1996 were within 25 km of major roads. A similar process has occurred in Indonesia and Central Africa. Dam construction is an infrastructure development mostly affecting forests in Southeast and East Asia. Dams flood large populated areas, forcing migration or resettlement to more environmentally sensitive areas. This is turn lead to deforestation, degradation of forests and increased erosion. However, unlike roads dams have a compensating affect by increasing water spread area and greenery for a long time period over large tracts. Wood extraction: Another direct cause of forest land-use change is wood extraction from natural forests. Despite the growing importance of plantations as a source of wood supply, wood extraction in the form of commercial timber, poles, fuel wood, and charcoal continues to degrade mature natural forests in many parts of the world. In the case of commercial logging, tree removal methods are frequently destructive and unsustainable. This is often the case on steep slopes and in sensitive ecosystems such as mangroves. Also, though many tropical countries in Africa, Asia and Latin America rely on logging timber for export earnings. However, under this reforestation is common.


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Harvesting forests for timber: Harvesting is an important factor in the global loss of forest cover but it often causes degradation rather than deforestation, as old growth is replaced with younger ecosystems or fewer species, or as areas are only partially logged. The extent of forest cover is most threatened when farmers, ranchers and fuel wood collectors move in to clear the land for other economic uses after harvesting is complete. According to the FAO (FRA 2000), timber harvesting takes place on some 110,000 km2 of tropical forests each year. Harvesting forests for pulp and paper production: Paper manufacture accounts for some 14% of the total world wood harvest. Most of the fibre used for pulp comes from managed temperate forests (only 2% from natural hardwood or tropical forests). The IIED in their study on “The Sustainable Paper Cycle” found that the sources of wood fibre mainly originate from managed natural regeneration forests (37%), plantations (29%) and thirdly from unmanaged natural regeneration forests (17%). Original conifer forest account for 15% while tropical rainforests and hardwood forests account for only 2% of the global wood pulp. Europe, North America and Japan are increasingly using recycled paper as a source of fibre. Acid rain and atmospheric pollutants: The most common form of atmospheric pollution believed to affect forests is ‘acid rain,’ defined as precipitation containing high levels of sulfuric or nitric acid. Acid rain and air pollution degrade forest vegetation. Damage varies with tree species and soil composition. Research in Eastern Europe, where in the past severe atmospheric pollution took place, is clarifying the links between this pollution and forest vegetation. Forests seem to recover well from mild pollution damage but more slowly with severe damage. Research on forest recovery is under way in an area of the Czech republic where 50% of the forest died in 1989 due to atmospheric pollution. On the other hand, there is evidence that carbon dioxide in the atmosphere increases the growth rate of forests. Radiation is another form of pollution. According to the University of Voronezh in Russia, 70,000 km2 of forest in Russia, Belarus and Ukraine were degraded by the nuclear accident in Chernobyl. Loss of forests to fire: Fires are a key driver of forest land-use change. A United Nations Environment Programme (UNEP) study estimates that annually fires burn up to 500 million hectares of woodland, open forests, tropical and sub-tropical savannas, 10-15 million hectares of boreal and temperate forest and 20-40 million hectares of tropical forests. Yet, fire is a paradox as while it can cause extensive ecological, economic, and social damage it can also be extremely beneficial through nutrient recycling and regeneration. For example in boreal forests, fire is a natural part of the forest cycle with some tree species, notably Lodge pole Pine and Jack Pine being able to germinate only after they have been exposed to fire. In addition, burning quickly decomposes organic matter into mineral components that cause a spurt of plant growth, and can also reduce disease in the forest. Nevertheless, forest fires in contrast have caused considerable environmental, health, economic and social damages in recent years and have been recognized as major cause of forest loss and degradation in some parts of the world. Furthermore, emissions from forest fires have also exacerbated global climate change.


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Human activities can start fires deliberately or accidentally. These accidents can be caused by careless use of fire for the clearing of land or other purposes. They can burn out of control for long periods of time. Burned areas can recover but they are vulnerable because fires open up large areas of forest and the ash increases the fertility of the soil, thereby giving an incentive to agricultural use. Areas of concern include the Mediterranean forests, tropical forests and boreal forests in northern China and Siberia. A prominent example of deforestation by fire is the case in1997-1998 in Sumatra and Borneo (Indonesia). Although there was wide disagreement at first, the final consensus is that 20,000 km2 of land had burned, only some of it being forest. Conversion of forests for expansion of cash crops production in developing countries: Many developing countries have large debts requiring foreign ‘hard’ currency to pay the interest. The incentive is then to convert forests to expand the production of export crops such as palm oil, rubber or coffee. Sometimes economic policies, such as Structural Adjustment Policies (SAPs) that are meant to address economic crises, may encourage faster exploitation of resources such as forests and fisheries. In many cases, economic policies are followed but clauses calling for the protection of natural resources are ignored. Destruction of forests in the course of warfare: Warfare can lead to long-lasting deforestation. Forest fires can be set off in a battle, deliberately or not. The Vietnam War can be cited, but also conflicts in Myanmar (Burma) and Sri Lanka. Alien invasive species: As the global movement of people and products spreads, so does the movement of plant and animal species from one part of the world to another. When a species is introduced into a new habitat – for example, oil palm from Africa into Indonesia, Eucalyptus species from Australia into California, and rubber from Brazil into Malaysia – the alien species typically requires human intervention to survive and reproduce. Often these alien species are economically important and enhance the production of forest commodities in many parts of the world. However, in some cases species introduced intentionally become established in the wild and spread at the expense of native species, affecting entire ecosystems. Perhaps even worse are invasive alien species that are introduced unintentionally, such as disease organisms that can devastate an entire tree species (e.g. Dutch elm disease and chestnut blight in North America) or pests that can have a major effect on native forests or plantations (e.g. gypsy moths and long-horned beetles). As global trade grows, so does the threat from devastating invasive species of insect and pathogen. These could fundamentally alter natural forests and wipe out tree plantations, the latter being especially vulnerable because of their lower species diversity. Absence of Good Governance and Rule of Law: Government policies, and how those policies are enforced, both within and outside the forest sector, also ultimately impact on forestland use change. Forestland is still all too often seen as a nationally owned asset, irrespective of the stewardship that local communities have exercised over the same resource for many years. Inequities in titling and use rights can


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result in forests becoming a major source of conflict and/or illegal activity. While illegal logging and corruption may, and often does, exist because of pure criminality it can, in some situations, be driven by inappropriate governance structures that turn legitimate concerns or entitlements into illegal activities. For example, in one Central American country in the early 1990s one of the main causes for bribery associated with log transport permits was not that loggers want to move illegally harvested trees but rather that they wanted to avoid long bureaucratic delays in attaining permission that would leave legally harvested trees deteriorating in forest loading yards. 7.4

Agriculture related Land Use Changes

Agriculture refers to the production of goods through the growing of plants, animals and other life forms. The history of agriculture is a central element of human history, as agricultural progress has been a crucial factor in worldwide socio-economic changes. Weather-building and militaristic specializations rarely seen in hunter-gatherer cultures are commonplace in agricultural and agro-industrial societies—when farmers became capable of producing food beyond the needs of their own families. It is argued that the development of civilization required agriculture. As of 2006, an estimated 45 percent of the world’s workers are employed in agriculture (from 42% in 1996). This has got both direct and indirect affects. The indirect effects have more environmental consequences. As of late 2007, several factors have pushed up the price of grain used to feed poultry and dairy cows and other cattle, causing higher prices of wheat (up 58%), soybean (up 32%), and maize (up 11%) over the year. Approximately 40% of the world’s agricultural land is seriously degraded. In Africa, if current trends of soil degradation continue, the continent might be able to feed just 25% of its population by 2025, according to UNU’s Ghana-based Institute for Natural Resources in Africa. According to the United Nations, the livestock sector (primarily cows, chickens, and pigs) emerges as one of the top two or three most significant contributors to our most serious environmental problems, at every scale from local to global. Livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the planet. It is one of the largest sources of greenhouse gases—responsible for 18% of the world’s greenhouse gas emissions as measured in CO2 equivalents. By comparison, all transportation emits 13.5% of the CO2. It produces 65% of human-related nitrous oxide (which has 296 times the global warming potential of CO2) and 37% of all human-induced methane (which is 23 times as warming as CO2). It also generates 64% of the ammonia, which contributes to acid rain and acidification of ecosystems. But studies have shown that a cow is climate neutral since it eats grass, corn. These plants take the CO2 out of the air. To meet the food needs of ever increasing population around 60’s green revolution technology was introduced in the system. The production is primarily related to water availability and chemical inputs. The water availability was related to tanks built by rulers of the day. Then open wells, then bore wells and small &


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big dams. According to a report of the World Commission on Dams, there are around 50,000 dams around the world of which 45% are in China, 14% are in USA, 9% are in India, 6% in Japan, 3% in Spain, the rest in 23%. After this accounting, China built the largest dam (Three Gorges). With this system changed the crops & cropping pattern; multiple cropping to sole crop; dry land to wet land agriculture. With dams, forests are submerged and water spread has increased. Thus, land use changed in multifold. To produce chemical inputs, industries were established that introduced greenhouse gases into the atmosphere. They introduced mining for raw material used in these industries. Thus, land use changed. For lift irrigation, power is used; and in the power production again contributing greenhouse gases. These industries induced severe health hazards on life forms. The food produced under the green revolution technology is polluted and as a result health hazards. This introduced industries to produce medicine that are causing severe pollution to air, water & soil; causing soil degradation. The vicious circle became a never- ending phenomenon. In affect the agriculture changed the land-use & land cover in terms of crops/cropping pattern and water reservoirs on the one hand; and at the same time introduced greenhouse gases and health hazards to life forms on the Earth and they in turn introduced green house gases. The land use changes here contribute changes in net radiation as well atmospheric water vapour balance and advection of energy. However, not much work has been done in this direction. Thus only qualitative statements and no quantitative estimates are available at global level. 7.5

Urbanization related Land Use Changes

Metropolitan areas around the globe irrespective of developed or developing nations are growing at unprecedented rates, creating extensive urban landscapes. Many of the farmlands, wetlands, forests, and deserts have been transformed during the past 100 years into human settlements, known as “concrete jungle”. Almost every one has seen these changes to their local environment but without a clear understanding of their impacts on environment and life forms. It is not until we study these landscapes from a spatial and temporal perspective that we can measure the changes that have occurred and predict the impact of changes to come. Most major metropolitan areas face the growing problems of urban sprawl, loss of natural vegetation and open spaces as well water bodies and converting these into concrete structures in both horizontal-vertical spectrum with roads. The public identifies with these problems when they see residential and commercial development replacing undeveloped land around them. Urban growth rates show no signs of slowing, especially when viewed at the global scale, since these problems can be generally attributed to increasing population. Cities have changed from small, isolated population centers to large, interconnected economic, physical, and environmental features. Urban growth and the concentration of people in urban areas are creating societal problems worldwide. One hundred years ago, approximately 15 percent of


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the world’s population was living in urban areas. Today, the percentage is nearly 50. In the last 200 years, world population has increased six times, stressing ecological and societal systems. Over the same time period, the urban population has increased 100 times; concentrating more people on less land even as the total land devoted to urbanization expands. Yet the temporal and spatial dimensions of the land use changes that shape urbanization are little know, even in the United States. A temporal database can be visualized as a sequence of maps, such as those presented in Figures 7a, b, c & d — examples of urban growth in Willamette Valley, Chicago-Milwaukee, Washington, D.C. & River watershed —. Sequential maps show urbanization as a static pattern that changes with each time period that is mapped: Figures 7a presents an example of urban change for Chicago-Milwaukee in 1955, 1975 & 1995. Each time period is represented by a different color. Black shows the extent of urban growth in 1955, red represents 1975, and yellow represents 1995. Figures 7b presents the time series documents of urban change in the Willamette Valley region over 115 years. The red areas represent urban extent for each time period. The Pacific Ocean and the Columbia River are shown in blue. Figures 7c presents the series of maps shows more than 200 years of urban growth in and around the Washington, D.C. area. The red areas represent urban extent for each time period and the blue is Chesapeake Bay. This figure also includes a projection for 2025 period given in yellow & green colours. Figures 7d presents series of maps compares changes in urban, agricultural, and forested lands in the Patuxent River watershed over the past 140 years. Red colour shows the extent of urbanization, gold shows extent of agriculture & green shows the extent of forestland. The existence and accessibility of transportation routes have often dictated patterns of urban growth. Urban areas that were established in the 18th and early 19th Centuries were usually located along waterways, reflecting dependence on shipping for the transportation of goods and people. By the middle of the 19th Century, railroads began to connect existing towns and spurred the growth of new urban areas. The post-World War II era saw not only an increase in the population of most metropolitan areas, but also the emergence of a society dependent on the automobile. The proliferation of the private automobile led to expansive development at the edges of many urban areas. The development of the Interstate Highway system in the 1950’s spurred the widespread construction of roads. As road networks expanded and became more complex, urban development followed. As in the past, most recent urban growth has occurred along transportation corridors. These introduced changes in the net radiation balance as well atmospheric water vapour balance along with greenhouse gases composition. These are assessed qualitatively but there is no quantitative data at global level. 7.6

Mining related Land Use Changes

Mining related land use change has direct and indirect impacts on environment. This is a phenomenon encompassing the whole world. However,


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the degree and intensity vary with country-to-country, location-to-location depending up on the prevailing natural geology, vegetative & orography conditions. Gold, copper, diamonds, and other precious metals and gemstones are important resources that are found in rainforests around the world. Extracting these natural resources is frequently a destructive activity that damages the rainforest ecosystem and causes problems for people living nearby and downstream from mining operations. In the Amazon rainforest most mining today revolves around alluvial gold deposits. Due to the meandering nature of Amazon Rivers, gold is found both in river channels and on the floodplains where rivers once ran. Large-scale operators and informal small-scale miners actively mine these deposits. Both operators rely heavily on hydraulic mining techniques, blasting away at riverbanks, clearing floodplain forests, and using heavy machinery to expose potential goldyielding gravel deposits. Large-scale mining operations, especially those using open-pit mining techniques, can result in significant deforestation through forest clearing and the construction of roads which open remote forest areas to transient settlers, land speculators, and small-scale miners. There are several other types of mines, namely coal, granite, raw material for cement, iron ore, other metals, etc. Some times, forest areas may not be cleared but this not only causes changes in land use-land cover but introduce pollutants into the atmosphere. Few general issues relating to mining are given below: • The mining dumps appalling amounts of waste into local streams, rendering downstream waterways and wetlands “unsuitable for aquatic life”; • Mines disturb large tracts of pristine forests and release harmful toxics, such as mercury, arsenic, cadmium, chromium and lead into soil and groundwater; • The toxic runoffs from mines not only disturb local freshwater fish and wildlife but can also have a damaging effect on humans; • Long-term exposure to arsenic is linked to skin cancer and other organ tumors, while cadmium exposure can cause kidney disease. Lead can stunt normal growth and development in children and some forms of mercury can cause damage to the nervous system; • Mining incursions in road less areas are also dependent on constructing a large network of access roads; • Road building damages the terrain and after all the resources are extracted, abandoned mines require more roads and cleanup teams to prevent toxic waste from damaging the ecosystem; • Forests are biologically rich with species of amphibians, birds, mammals and reptiles, and species of vascular plants. Mining affect the balance of these; • The mining process generates other toxic compounds including oil and fuel waste and fine suspended particles that affect river navigation and fish populations by reducing the availability of oxygen;


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• Mining further exposes previously buried metal sulfides to atmospheric oxygen causing their conversion to strong sulfuric acid and metal oxides, which run off into local waterways. Oxides tend to more soluble in water and contaminate local rivers with heavy metals; • Clandestine miners further damage the riparian environment by tearing up biologically sensitive areas including alluvial zones and small creek beds, key habitats for aquatic life. In the forest, they clear under story vegetation, while leaving some canopy trees to prevent patrol helicopters from landing; • These sites are difficult to locate with plane or helicopter, suggesting that mining damage may be underestimated; • Under story clearing can dry the forest, affecting species distribution and putting it at greater risk to forest fires; • In abandoned mining areas, cleared forest can take more than 100 years to re-grow; • In the meantime, the vegetation shift changes the entire ecology of the ecosystem, transitioning from closed tropical rainforest to a weedy, less bio-diverse landscape; • Beyond the environmental effects, mining has also been linked to the spread of malaria. The influx of prostitutes into mining camps has increased the incidence of AIDS and other sexually-transmitted diseases as well. Miners themselves are at risk. 7.7

Impact on Climate

When humans transform land from forests to seasonal crops or from natural to urban environments, the regional climate system is altered. For example, clearcut hillsides are significantly warmer than forests. Urban environments are also islands of heat produced by industry, homes, automobiles, and by asphalt’s absorption of solar energy. Changing uses of the land are also associated with changes in the usage and availability of water, as well as the production of GHGs. Deforestation can significantly increase the amount of atmospheric CO2. All these land use changes on a contiguous plot-form are likely to have a large, direct effect on global average temperature as well local & regional weather & climate in a complex way. Land use and land cover affect the global climate system through biogeophysical, bio-geochemical, and energy exchange processes. Variations in these processes due to land-use and land-cover change in turn affect local, regional, and global climate patterns. Key processes include uptake and release of GHGs by the terrestrial bio-sphere through photosynthesis, respiration, and evapotranspiration; the release of aerosols and particulates from surface land-cover perturbations; variations in the exchange of sensible heat between the surface and atmosphere due to land-cover changes; variations in absorption and reflectance of radiation as land-cover changes affect surface reflectance; and surface roughness effects on


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atmospheric momentum that are land-cover dependent. Human activity can and does alter many of these processes and attributes, but weather and climate, as well as geological and other natural processes, are also important. For example, land-cover changes such as deforestation and forest fires alter ecosystems cause short-term release of carbon dioxide, methane, carbon monoxide, and aerosols to the atmosphere and as well as cause long-term change in the reflectivity of the land surface, which in turn determines how much of the Sun’s energy is absorbed and thus available as heat, while vegetation transpiration and surface hydrology determine how this energy is partitioned into latent and sensible heat fluxes. At the same time, vegetation and urban structure determine surface roughness and thus air momentum and heat transport. Understanding the significance of land-cover changes for climate, biogeochemistry, or ecological complexity is not possible, however, without additional information on land use. This is because most land-cover change is now driven by human use and because land-use practices themselves also have major direct effects on environmental processes and systems. Evaluating the causes and the consequences of changes in land use and land cover is becoming an urgent need for more than the academic research community. At the 1992 UN Conference on Environment and Development, a framework convention on climate change and a convention on biodiversity were signed, as was a declaration of principles on forests; while no formal action was taken on desertification, a broad agreement was reached to work toward a conference and a convention in the near future. Changes in land use and land cover are significant components of all the problems addressed by these agreements, yet we do not have enough knowledge about such phenomena to decide how these conventions should best be structured and which of their proposed elements are likely to be effective. At present, we are unable to answer even the most basic questions. Recognizing the importance of studies of changes in land use and land cover in developing our understanding of global environmental change, the International Geosphere-Biosphere Programme (IGBP) and the Human Dimensions of Global Environmental Change Programme (HDP) formed an ad hoc working group in early 1991 to investigate the possibilities of a joint effort by natural and social scientists to study the issue. The group met in New York City with the assistance of the Social Science Research Council in May 1991 and in Dalaro, Sweden in October 1991, with support from the Swedish Council for Planning and Coordination of Research (FRN). Carolyn Malmstrom represented the IGBP Seaetariat at the New York meeting. Several additional individuals took part in the working group’s second meeting. The working group recommended that a joint IGBP-HDP Core Project Planning Committee be established to develop an interdisciplinary research programme involving social and natural scientists to project future states of land cover. This recommendation was based on the following conclusions of the working group: “Understanding the past and future impacts of changes in land cover is central to the study of global environmental change and its human driving forces and impacts, including hydrology, the climate system,


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biogeochemical cycling, ecological complexity, and land degradation and its impacts for agriculture and human settlement”. Additional basic research is required to understand how these factors interact to drive land cover change or how projections about them could be used to project future patterns of land use, future rates of land-cover change, and future states of land-cover. In light of the recommendation of the working group and the importance of the subject, the Scientific Committee of the IGBP and the Standing Committee of the HDP decided to establish a joint Core Project Planning Committee (CPPC), under the joint chairmanship of B L Turner and D L Skole, with responsibility to develop a detailed scientific plan for an IGBP-HDP project on changes in land use and land cover. It was further decided to hold an open scientific meeting to review the scientific plan that will be proposed by the CPPC. Assuming the subsequent establishment of the project, a Joint Scientific Steering Committee would then be formed to coordinate its implementation. 7.7.1 Heat Island Effect Kenneth Chang presented a report in New York Times, which was reproduced by San Jose Mercury Nes on August 22, 2000 “Urbanites feel the heat when cities replace trees and greenery with buildings and blacktop”. — Atlanta is so big and hot that it makes its own weather, and scientists have the pictures to prove it. While analyzing weather data that had been collected during the 1996 Summer Olympics, Dr. Robert Bornstein, a professor of meteorology at San Jose State University, saw a pattern in the winds. The heat absorbing roofs and pavement were warming the air, and the hot air was rising, sucking air from all directions into the city (Figure 7e). Bornstein surmised what was happening next: As the warm air rose, it cooled, condensing into clouds and rain. Satellite images backed him up, revealing several instances in which thunderstorms erupted over Atlanta, seemingly out of nowhere, and dumped rain on the city, usually at its southeast and northeast edges. The idea that cities generate their own heat, and alter their climates as a result, is not new. Bornstein observed thunderstorms appearing over New York City more than two decades ago, but in recent years, scientists using high-tech sensors have produced a more detailed picture of how human activities change the weather. Over the past four years, researchers from the NASA Marshall Space Flight Centre in Huntsville, Al., have flown jets equipped with infrared cameras over Salt Lake City, Sacramento, Baton Range, La., and Atlanta, producing block-by-block temperature maps. Figure 7f reveals surface temperatures on a summer day in 1998 in down town Sacramento – blue areas are vegetated and relatively cool, 77 to 86 degrees; red areas are 120 degrees and above. Figure 7g presents the surface temperatures in downtown Sacramento at 11 a.m. June 30, 1998. Air temperatures differ, depending on meteorological conditions. The other important issue in warming of urban areas is the destruction of water bodies. This is an important issue all over the world. Parks were cool – plants are full of cooling water, and trees also provide shade – while asphalting lots were hot. . The hottest


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buildings often were the newest. In Salt Lake City, the Scott M. Matheson Courthouse, a dark-roofed building that opened a couple of years ago, is a whitehot splotch in the infrared photograph, suggesting a roof temperature of about 170 degrees Fahrenheit. Across the street to the east, the century-old castle-like City and County Building is a relative cool reddish color. Figure 7h presents an example of horizontal section of heat island. The heat-island effect is growing with the outward push of suburbia. Atlanta’s urban heat island now covers at least 17 square miles. Luke Howard, an amateur meteorologist in England, first recorded the heat-island effect almost 200 years ago. Beginning in 1807, he started comparing temperatures from several sites within London with those measured a few miles beyond the city’s edge, and through the years, he noticed that the city was consistently warmer. “Thus,” Howard wrote in his book, “The Climate of London” in 1818, “under the varying circumstances of different sites, different instruments, and different positions of the latter, we find London always warmer than the country, the average excess of its temperature being 1.579 degrees”. Today, the effect is more noticeable. In the largest cities, average temperatures can range 5 to 10 degrees Fahrenheit hotter than surrounding areas. Figure 7i presents rate of heat island growth in degrees Fahrenheit per decade over different cities in USA. Similar studies were carried out all over the world including in India. Fact Sheet (Down To Earth, March 15, 2008) presents “City centers are physically hotter. Known as the heat island effect, urban and suburban temperatures are 1 to 6 0C


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hotter than nearby rural areas, says the US Environmental Protection Agency”. Globally the meteorological stations, primarily, are located in the “heat island” zones. Thus, the surface observations, on which global warming theories are built, is contaminated by the urban heat island effect. 7.7.2 Impact of Changes in Topography Topography plays the major role on Indian rainfall. For example, Western Ghats helps in producing wet areas on windward direction (western parts of Ghats) and dry areas on leeward direction (eastern parts of Ghats) during the Southwest


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Monsoon season. The opposite pattern is produced during the Northeast Monsoon season and as well due to cyclonic activity in Bay of Bengal. The box effect of northeastern zone provides the zone of the highest rainfall in the world. Thus, the destruction of topography changes the weather around that zone. Very few studies attempted to quantify these changes. Colaba and Santacruz within Mumbai show an increasing trend in rainfall during 1961-1990 with Santacruz rainfall higher than Colaba rainfall by around 300 mm but at Santacruz the increasing trend in rainfall was countered due to cutting of hillocks in the windward direction of Southwest Monsoon on the eastern and northeastern side of Santacruz meteorological observatory on the runway (Figure 7j). The mean annual rainfall at Colaba (1969, mm) and Santacruz (2288, mm) shows a difference of 318.8 mm. The same during a wet year it is –127 mm and a dry year it is 396 mm. That is, the change in topography in the windward area reduced the rainfall by around 150 mm.


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7.7.3 Cold Island Effect To meet the food and other needs of the unabated growth in population, in agriculture large-scale changes in land-use have taken place and this is a continuous process. In this process there are important changes are noticed, namely changes in crops & cropping pattern & the duration; and spread of reservoirs – rural ecological changes. These changes create changed weather system. Figure 7k presents the trend in 28-year period averages in the three meteorological sub-divisions in Andhra Pradesh in the two rainy seasons, namely the Southwest Monsoon (SWM) – left side and the Northeast Monsoon (NEM) – right side. The numbers on the curves present the % number of years the rainfall less than the average rainfall during the respective monsoon seasons (SWM/NEM) in each of the three meteorological subdivisions of Andhra Pradesh. It is clear from the figure that the trend is significant and early in Coastal Andhra sub-division in which the changes in agriculture took place earlier with the two dams, one on Krishna at Vijayawada and the other on Godavari at Rajahmundry. Rayalaseema sub-division presents a weak-trend as the land use change is limited to smaller areas only. Table 9 presents the temporal variation in the area under irrigation in the three meteorological sub-divisions of AP. However, in Andhra Pradesh, the state government initiated cloud seeding operations since 2004 along with several other changes in land use and changes in land cover, which may change the rainfall over different parts of the state in near future. The state receives rainfall predominantly in association with cyclonic systems. The cloud seeding operators are seeding invariably such cyclonic systems that severely affect the rainfall in downwind direction. At present it is not easy to separate this from the trend in rainfall but the preliminary analysis of the result clearly indicate a decrease in rainfall in down wind direction (Reddy, 2004). Table 9: Temporal variation of the irrigated area in the three sub-divisions of AP Region

Area under irrigation (lakh hectares) 1955-56

1999-00

17.23

22.01

Telangana

6.43

15.71

Rayalaseema

3.81

6.12

27.47

43.84

Coastal Andhra

AP

7.7.4 Deforestation Effect Tropical Deforestation Affects US Climate (Mike Bettwy, Goddard Space Flight Center release September 20, 2005) results are summarized as: Today, scientists estimate that between one-third and one-half of our planet’s land surfaces have been transformed by human development. Now, a new study is offering insight into the long-term impacts of these changes, particularly the effects of large-scale deforestation in tropical regions on the global climate. Researchers from Duke


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University, Durham, N.C., analyzed multiple years of data using the NASA Goddard Institute for Space Studies General Circulation Computer Model (GCM) and Global Precipitation Climatology Project (GPCP) to produce several climate simulations. Their research found that deforestation in different areas of the globe affects rainfall patterns over a considerable region. Deforestation would result in a reduction in precipitation and increase in temperature in the Amazon basin — This pattern was also revealed in studies carried out in early 1970s by India Meteorological Department on the impact of deforestation on Simla rainfall. “Our study carried somewhat surprising results, showing that although the major impact of deforestation on precipitation is found in and near the deforested regions, it also has a strong influence on rainfall in the mid and even high latitudes,” said Roni Avissar, lead author of the study, published in the April 2005 issue of the Journal of Hydrometeorology. Specifically, deforestation of Amazonia was found to severely reduce rainfall in the Gulf of Mexico, Texas, and northern Mexico during the spring and summer seasons when water is crucial for agricultural productivity. Deforestation of Central Africa has a similar effect, causing a significant precipitation decrease in the lower U.S Midwest during the spring and summer and in the upper U.S. Midwest in winter and spring. Deforestation in Southeast Asia alters rainfall in China and the Balkan Peninsula most significantly. Elimination of any of these tropical forests, Amazonia, Central Africa or Southeast Asia, considerably enhances rainfall in the southern tip of the Arabian Peninsula. However, the combined effect of deforestation in all three regions shifts the greatest precipitation decline in the U.S. to California during the winter season and further increases rainfall in the southern tip of the Arabian Peninsula. Improved understanding of tropical forested regions is valuable to scientists because of their strong influence on the global climate. The tropics receive twothirds of the world’s rainfall, and when it rains, water changes from liquid to vapor and back again, storing and releasing heat energy in the process. With so much rainfall, an incredible amount of heat is released into the atmosphere - making the tropics the Earth’s primary source of heat redistribution. Avissar says, “Deforestation does not appear to modify the global average of precipitation, but it changes precipitation patterns and distributions by affecting the amount of both sensible heat and that released into the atmosphere when water vapor condenses, called latent heat. Associated changes in air pressure distribution shift the typical global circulation patterns, sending storm systems off their typical paths”. The accelerating destruction of the rainforests that form a precious cooling band around the Earth’s equator, is now being recognized as one of the main causes of climate change. Carbon emissions from deforestation far outstrip damage caused by planes and automobiles and factories. The rampant slashing and burning of tropical forests is second only to the energy sector as a source of greenhouse gases according to report published by the Oxford-based Global Canopy Programme, an alliance of leading rainforest scientists. “Tropical forests are the elephant in the living room of climate change,” said Andrew Mitchell, the head of the GCP. Scientists


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say one days’ deforestation is equivalent to the carbon footprint of eight million people flying to New York. Reducing those catastrophic emissions can be achieved most quickly and most cheaply by halting the destruction in Brazil, Indonesia, the Congo and elsewhere. The rainforests of the Amazon, the Congo basin and Indonesia are thought of as the lungs of the planet. But the destruction of those forests will in the next four years alone, in the words of Sir Nicholas Stern, pump more CO2 into the atmosphere than every flight in the history of aviation to at least 2025. Indonesia became the third-largest emitter of greenhouse gases in the world last week. Following close behind is Brazil. Neither nations have heavy industry on a comparable scale with the EU, India or Russia nor yet they comfortably outstrip all other countries, except the United States and China. Standing forest was not included in the original Kyoto protocols and stands outside the carbon markets that the report from the IPCC pointed to this month as the best hope for halting catastrophic warming. The landmark Stern Report last year, and the influential McKinsey Report in January agreed that forests offer the “single largest opportunity for cost-effective and immediate reductions of carbon emissions”. The standing forests generate the bulk of rainfall worldwide and act as a thermostat for the Earth. Forests are also home to 1.6 billion of the world’s poorest people who rely on them for subsistence. However, forest experts say governments continue to pursue science fiction solutions to the coming climate catastrophe, preferring bio-fuel subsidies, carbon capture schemes and next-generation power stations. Putting a price on the carbon these vital forests contain is the only way to slow their destruction. Hylton Philipson, a trustee of Rainforest Concern, explained: “In a world where we are witnessing a mounting clash between food security, energy security and environmental security - while there’s money to be made from food and energy and no income to be derived from the standing forest, it’s obvious that the forest will take the hit.” Slash-and-burn agriculture elsewhere (in particular in Indonesia, Southeast Asia and tropical Africa in dry years) may also have a profound effect on climate (McGuffie, K. and A. Henderson-Sellers in 1997). It can be argued that because the smoke CCN are short-lived, and because the CO2 emissions involved are relatively small, the direct effect of the burning on climate is mostly transient and therefore deforestation is of little importance to climate. However the long-term change in land surface conditions may have a lasting effect on climate through changes in surface heat fluxes, rainfall, and greenhouse gas production (e.g. methane). All these, clearly reflects that ecological changes have both direct and indirect effects on weather in addition to direct impact on environment & life forms on the Earth. Unfortunately, the researchers’ haven’t given that much importance as that given to hypothetical global warming theories as these needs only sophisticated computers without scientifically validated data sets. There is an urgent need to change the mind set in this direction to solve the climate change problem as a


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long-term solution. From the above discussions it is also clear that ecological changes not only influence the radiation balance in the atmosphere but also the greenhouse gases, principally CO2 balance in the atmosphere. This creates a permanent change in the greenhouse gases balance in the atmosphere. The principal contributors of anthropogenic greenhouse gases are fossil fuels such as coal, oil & gas. It was estimated in 2005 that the total world-wise energy consumption was 138,900 Twh with around 85%± 10% (oil 37%, coal 25% & gas 23%) of primary energy production in the world come from burning fossil fuels are non-renewable. World recoverable coal reserve is estimated as 4,416,000 million barrels equivalent. At the present rate (29 million barrels equivalent per day) of use, it will lost up to 417 years. Oil reserves are 1,317,000 million barrels will lost (84 million barrels per day) for 43 years and gas 1,161,000 million barrels equivalent lost (19 million barrels equivalent per day) for 167 years. It is proposed to use renewable energy sources that are naturally replenishble, such as sunlight, wind, rain, tides and geothermal heat in place of fossil fuels to reduce the greenhouse gases emissions into the atmosphere. Renewable technologies include solar power, wind power, hydroelectric power, biomass, etc. In 2006, about 18% of global final energy consumption come from renewables, with 13% coming from traditional biomass such as wood burning. Hydropower was the next largest with 3%. We need spectacular breakthroughs in technologies to stop or reduce the use of fossil fuels in energy production. However, in light of the ecological changes changing the greenhouse gases balance in the atmosphere, there is a need to re-look into the greenhouse gases vs global warming theories proposed based on numerical models.


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Chapter 8

Global Warming 8.1

What is Global Warming (GW)?

Global warming is the increase in the average temperature of the Earth’s near-surface air and Oceans since the mid-twentieth century, and its projected continuation. The average global air temperature near the Earth’s surface increased by 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the hundred years ending in 2005. The basic question is whether the observed increase in globally averaged temperatures since the mid-twentieth century is due to the observed increase in anthropogenic (man-made) greenhouse gases (GHGs) concentrations via the greenhouse effect or due to a combination of natural and man made effects like urban contamination. A report says, “There is a related question of whether warming is due to human activities or the end of a little ice age. The main external climate forcings experienced over the last 2,000 years are volcanic eruptions, changes in solar radiation reaching the Earth, and increases in atmospheric greenhouse gases and aerosols due to human activities. Proxy records are available for reconstructing climate forcings over the last 2,000 years, but these climate forcings reconstructions are associated with as much uncertainty as surface temperature reconstructions”. The report also says, “Greenhouse gases and tropospheric aerosols varied little from A.D. 1 to around 1850. Volcanic eruptions and solar fluctuations were likely the most strongly varying external forcings during this period, but it is currently estimated that the temperature variations caused by these forcings were much less pronounced than the warming due to greenhouse gas forcing since the mid 19th century. Climate model simulations indicate that solar and volcanic forcings together could have produced periods of relative warmth and cold during the preindustrial portion of the last 1,000 years. However, anthropogenic greenhouse gas increases are needed to simulate late 20th century warmth”. Report from the National Academy of Sciences - National Research Council (NAS/NRC) entitled CLIMATE CHANGE SCIENCE, AN ANALYSIS OF SOME KEY QUESTIONS marks the first time a study commissioned by the federal government has publicly concluded that global warming exists. The study says that global warming “is real and particularly strong within the past 20 years”. A total of 14 specific questions were addressed by the study, ranging from “Is climate change occurring? If so, how?” to “What are the specific areas of science that need to be studied further, in order of priority, to advance our understanding of climate change?” The report further states “greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact, rising”. The report notes that “changes observed over the last several decades are likely mostly due to human activities,” but the NAS/NRC says, could not rule out the possibility that a significant part of the climate changes could be the result of natural variability.


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Regardless of the reason for the climate change, global warming is expected to continue through the 21st century. While in some areas, the rising temperatures will cause a rise in sea level. Computer model simulations also project “an increased tendency towards drought over semi-arid regions, such as the U.S. Great Plains”. The NAS/NRC also looked for substantive differences between the Intergovernmental Panel on Climate Change (IPCC) Report and its published summary. According to the NAS/NRC, the IPCC summary “largely represents the consensus scientific views and judgments of the committee members, based on the accumulated knowledge that these individuals have gained – both through their own scholarly efforts and through formal and informal interactions with the world’s climate change science community.” One of the specific questions asked of the NAS/NRC was “By how much will temperatures change over the next 100 years and where?” The highest estimate of the atmospheric temperature increase is 10.4oF. While this may not seem to be a particularly large change when looking on the short term, the long-term impact of such a change is significant. According to their report, “Higher evaporation rates would accelerate the drying of soils following rain events, resulting in lower relative humidities and higher daytime temperatures, especially during the warm season”. There is evidence to suggest that droughts as severe as the “dust bowl” of the 1930’s were much more common during the 10th and 14th centuries than they have been in recent record. Another major question the study addressed was, “What will be the consequences (e.g., extreme weather, health effects) of increases [in temperature] of various magnitude?” The study concludes “Hydrologic impacts could be significant over the western United States, where much of the water supply is dependent on the amount of snow pack and the timing of the spring runoff.” This is a small example, how global warming theory is running on “ifs and buts” that needs clear-cut solutions!!! National Research Council of USA in its’ 2006 report presented smoothed reconstructions of large scale (Northern Hemisphere and global mean) surface temperature using different paleoclimatological proxy data sets. The data sets present large differences among different reconstructed temperature pattern with time. The basic question is how realistic is to compare present trend with past obtained from such proxy data series? 8.2

Global Climate Models

With the advent of modern fast and sophisticate computers, use of models in solving problems has increased multifold in all areas of science. However, models have significant limitations basically because they carryout as per the creation by the human brain that may not take into account all physical process involved in the nature. But, computers can handle huge quantity of data that human brain can’t handle. Thus people started meddling with models and they became a special class in scientific community. Thus models become “Survival Research” tools


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without proper understanding of physical process in right perspective, this is more so in climate & weather studies and thereby ground based studies took back-seat. Let me present an example from my experience in late 70’s of a crop growth model (SORGF model), developed under extra-tropical conditions and tried to implement the same in tropical conditions. Temperature is the limiting factor in ex-tropical conditions and moisture is the limiting factor under tropical conditions for the crop production. Because of this, the model failed in the tropical conditions. The model gave root mean square errors and correlation coefficients for dry matter and grain yields respectively: 27.58 and 17.39 q/ha, and 0.35 and 0.37. By changing the moisture parameters, estimated using a model (Reddy, 1983c) developed under tropical conditions, gave 15.06 and 8.49 q/ha, and 0.85 and 0.81, respectively (Reddy, 1983-84). However, the authors of the SORGF model refused to change the model structure. Thus, with the changed management came another model developed in the extra-tropical conditions by another group of scientists; and again this is also replaced. The process continued to meet the survival research needs. The same tendency is seen in the study of McKenny & Rosenberg (1993) “Sensitivity of some potential evapotranspiration estimation methods to climate change”. The fact is that the authors tried to estimate potential evapotranspiration using highly erroneous models. Thus, the study of senstivity of such estimates has no meaning. Computer models of the Earth’s climate system are known as general circulation models (GCMs). The validity of such models depends upon soundness in their physical basis, and their skill in representing observed climate and past climate changes. Though, the models are based on physical principles of fluid dynamics, radiative transfer, and other processes, started using with simplifications, as the climate system is complex. All modern climate models include an atmospheric model that is coupled to the Ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes. These models predict that the effect of adding GHGs is to produce a warmer climate. However, even when the same assumptions of future GHG levels are used, there still remains a considerable range of climate sensitivity, as it is not clear how and in what way the GHGs increase temperature. Prior to 2001 the estimates of global warming were made from a range of climate models under the IPCC Special Report on Emissions [SRES] A2 emissions scenario, which assumes no action is taken to reduce emissions. Figure 8a presents an example of global warming projections by different models. They present temperatures at the end of 2100 varying between 2 and 5 °C. The geographic distribution of surface warming during the 21st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and GHG emissions. In this the globally averaged warming corresponds to 3.0 °C (5.4 °F). Including uncertainties in future GHG concentrations and climate modeling, the IPCC anticipates a warming of 1.1 °C to 6.4 °C by the end of the 21st century, relative to 1980–1999.


8.3

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Factors Contributing GW

8.3.1 The Natural Heating & Cooling Greenhouse gases and greenhouse effect: The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet’s lower atmosphere and surface. Existence of the greenhouse effect as such is not disputed. Naturally occurring GHGs have a mean warming effect, without which the Earth would be uninhabitable. On the Earth, the major GHGs are water vapour, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide

(CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone, which causes 3–7%. The issue is how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of some GHGs? It is reported that “Human activity since the industrial revolution has increased the concentration of various GHGs, such as CO2, methane, tropospheric ozone, CFCs and nitrous oxide. It is stated that molecule for molecule, methane is a more effective GHG than carbon dioxide, but its concentration is much smaller so that its total radiation exchange capacity is only about a fourth of that from carbon


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dioxide. Some other naturally occurring gases contribute very small fractions of the greenhouse effect; one of these, nitrous oxide (N 2O), is increasing in concentration owing to human activity such as agriculture. It is also stated that the atmospheric concentrations of CO2 and CH4 have increased by 31% and 149% respectively since the beginning of the industrial revolution in the mid-1700s – though in percentage-wise it looks high with methane over carbon dioxide but in terms of volume it is the carbon dioxide higher than methane. These percentages are relative to non-instrumental observations. From less direct geological evidence it is believed that CO2 values this high were last attained 20 million years ago. Fossil fuel burning has produced approximately three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land use change, in particular deforestation”. The exactness of this is in question!!! World Meteorological Organization (WMO) compiled data relating to carbon dioxide and stations recording it. The fact remains that the GHG concentrations for the past are built on indirect methods of estimation. Figure 8b [Source: Siegen Thaler & Oeschger, Tellus, 39B: 140-154, 1987] presents the atmospheric carbon dioxide increase in the past 200 years as indicated by measurements on air trapped in old

ice from Siple station, Antarctica, by infrared laser spectroscopy (full triangles) & by gas chromatography (open squares) and the annual mean values from Mauna Loa Observatory (crosses). That means, only in the last five decades it is measured


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and that too at few selected locations (Figure 8c), which are unevenly distributed over different parts of the globe [Source: WMO Fact Sheet No. 4, August 1989]. Figure 8d presents (Robinson et al., 1988 – Review in Geophysics, 1988) monthly mean CO 2 concentrations at the NOAAGeophysical Monitoring for Climate Change Laboratory at South Pole and Barrow, Alaska Observatories, 1973-1987. The monthly CO 2 measurements display seasonal oscillations in an overall yearly up trend; each year’s maximum is reached during the Northern Hemisphere’s late spring, and declines during the Northern Hemisphere growing season as plants remove some CO2 from the atmosphere. Under the changed CO2 sinks scenarios, the balance must change!!! Reports say, “Recent data indicate that carbon dioxide is accumulating in the atmosphere at a greater rate than in the past. In 2005 the concentration of carbon dioxide in the atmosphere increased by 2.5 parts per million (ppm), the third largest annual increase ever recorded. Although there is considerable inter-annual variability in the rate of increase in atmospheric carbon dioxide, the rise has been more than 2 ppm in 3 of the last 4 years. Prior to 1995, an annual increase of more than 2 ppm was seen only 4 times since the record began in 1959. As a result of


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recent jumps, the current atmospheric concentration of carbon dioxide is now over 380 ppm. This is an increase of more than 100 ppm since the start of the Industrial Revolution, and ice core records show that it is the highest concentration of atmospheric carbon dioxide for at least the last 650,000 years”. Figure 8e presents the total fossil fuel consumption, which is identified as the main source of the observed CO 2 increase, in Southern and Northern Hemispheres. The projections for the year 2000 compared with those of 1960 indicate that consumption will have more than quadruples in the Southern Hemisphere while that in the Northern Hemisphere will have more than doubled in relative terms but in magnitude the Northern Hemisphere consumed more over the Southern Hemisphere. From the WMO Fact Sheet No. 4 (August 1989), it is clear that very few stations are measuring changing composition [Figure 8c] of the atmosphere, including the increases of GHGs (CO2, CH4, N2O, tropospheric O3, CFCs) especially in tropics (by that time no data) and the Southern Hemisphere (by that time only three sites]. With such a data sets, presenting un-believably smooth curve, scientists are filling the literature with highly hypothetical inferences. Tropospheric Ozone: Tropospheric ozone (see Chapter 2) is created by chemical reactions from automobile, power plant and other industrial and commercial source emissions in the presence of sunlight. It is estimated that O3 has increased by about 36% since the pre-industrial era, although substantial variations exist for regions and overall trends (IPCC, 2007). Besides being a GHG, ozone can also be a harmful air pollutants at ground level, especially for people with respiratory diseases and children and adults who are active outdoors. Chlorofluorocarbons (CFCs) & Hydrochlorofluorocarbons (HCFCs): CFCs & HCFCs are used in coolants, foaming agents, fire extinguishers, solvents, pesticides and aerosol propellants. These compounds have steadily increased in the atmosphere since their introduction in 1928. Concentrations are slowly declining as a result of their phase out via the Montreal Protocol on Substances that deplete the ozone layer [see Chapter 2). Fluorinated gases such as Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), and Sulfur hexafluoride (SF6) are frequently used as substitutes for CFCs and HCFCs and are increasing in the atmosphere. It is noted that these various fluorinated gases are sometimes called “high global warming potential greenhouse gases” because, molecule for molecule, they trap more heat than CO2 . Aerosols: The burning of fossil fuels and biomass (living matter such as vegetation) has resulted in aerosol emissions into the atmosphere. Aerosols absorb and emit heat, reflect light and, depending on their properties, can either cool or warm the atmosphere. Sulfate aerosols are emitted when fuel-containing sulfur, such as coal and oil, is burned. Sulfate aerosols reflect solar radiation back to space and have a cooling effect. These aerosols have decreased in concentration in the past two decades resulting from efforts to reduce the coal fired power plant emissions of sulfur dioxide in the United States and other countries. Black carbon (or soot) results from the incomplete combustion of fossil fuels and biomass burning (forest


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fires and land clearing) and is believed to contribute to global warming (IPCC, 2007). Though global concentrations are likely increasing, there are significant regional differences. Other aerosols emitted in small quantities from human activities include organic carbon and associated aerosols from biomass burning. Mineral dust aerosols (e.g., from deserts and lake beds) largely originate from natural sources, but their distribution can be affected by human activities. Fossil Fuels & Land use changes: The present atmospheric concentration of CO2 is about 385 parts per million (ppm) by volume. Future CO2 levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, and natural developments & technological inventions but may be ultimately limited by the availability of fossil fuels. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100 – this range indicates, no body knows the reasonable level of carbon dioxide by 2100. Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100. Research by NASA climate scientist James Hansen indicates mainly GHGs other than carbon dioxide have driven the 0.75 °C rise in average global temperatures over the last 100 years. Though he is the first few to claim linking CO2 to global warming in 1981. With this the politics of global warming has taken a new twist, conflict between developing and developed countries. CO2 Produces CO2: It is reported that the heating or cooling of the Earth’s surface can cause changes in GHG concentrations. That is, when global temperatures become warmer, CO2 is released from the Oceans. When changes in the Earth’s orbit trigger a warm (or interglacial) period, increasing concentrations of CO2 may amplify the warming by enhancing the greenhouse effect. When temperatures become cooler, CO2 enters the Ocean and contributes to additional cooling. During at least the last 650,000 years, CO2 levels have tended to track the glacial cycles (IPCC, 2007). That is, during warm interglacial periods, CO2 levels have been high and during cool glacial periods, CO2 levels have been low. This means, the high year-to-year variations in temperature must contribute significant changes in CO2 levels, which is not seen in Figure 8b, though there are significant seasonal changes (Figure 8d). The curve in Figure 8b presents a smooth curve without much variation. However, one thing is clear from the above discussions that during glacial and interglacial periods, the changes in temperatures of the Ocean changed the CO2 levels and not vice-versa. 8.3.2 Radiative Forcing Radiation forcing (RF) is the change in the balance between solar radiation entering the atmosphere and the Earth’s radiation going out. On an average, a positive RF tends to warm the surface of the Earth while negative RF tends to cool the surface. It is reported that GHGs have a positive RF because they absorb and emit heat. Aerosols can have a positive or negative RF, depending on how they absorb and emit heat and/or reflect light. For example, black carbon aerosols which have a positive factor - more effectively absorb and emit heat than sulfates, which have a negative factor and more effectively reflect light.


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IPCC (2007) presented estimates of the change in RF in the year 2005 relative to 1750 for different components of the climate: “It is reported that the RF contribution (since 1750) from increasing concentrations of well-mixed GHGs (including CO2 , CH4, N2O, CFCs, HCFCs, and fluorinated gases) is estimated to be +2.64 Watts per square meter - over half due to increases in CO2 (+1.66 Watts per square meter), strongly contributing to warming relative to other climate components; The RF contribution from increasing tropospheric ozone, an unevenly distributed GHG, is estimated to be +0.35 Watts per square meter (on average), resulting in a relatively small warming effect. This factor varies from region to region depending on the amount of ozone in the troposphere at a particular location. The RF contribution from the observed depletion of stratospheric ozone is estimated to be -0.05 Watts per square meter, resulting in a relatively small cooling effect. While aerosols can have either positive or negative contributions to RF, the net effect of all aerosols added to the atmosphere has likely been negative. The best estimate of aerosols’ direct cooling effect is -0.5 Watts per square meter; the best estimate for their indirect cooling effect (by increasing the reflectivity of clouds) is -0.7 Watts per square meter, with an uncertainty range of -1.8 to -0.3 Watts per square meter. Therefore, the net effect of changes in aerosol RF has likely resulted in a small to relatively large cooling effect”. For well-mixed GHGs, mathematical equations are used to compute RF based on changes in their concentration relative to 1750 (or 1990 for NOAA’s AGGI) and the known radiative properties of the gases. IPCC claim “high confidence in these calculations due to reliable current and historic concentration data and well-established physics”. The uncertainty factor clearly demonstrates that these estimates are highly unreliable. Due to limited measurements and regional variation, changes in tropospheric ozone, aerosols, land use (see Chapter 7) and the Sun’s intensity are much more uncertain. In the case of aerosols, uncertainty is increased due to an incomplete understanding of how aerosols interact with clouds and the effects the interactions have on aerosol RF. That means, the whole theory behind RF effects of different components are of hypothetical in nature and there is nothing to prove their accuracy, though in GHGs they claim high confidence. The calculated data presented above of combined effect of GHGs and aerosols appear to be negligible; may be a little “heating or cooling”. 8.3.3 Feedback Factors Evaporation: Various feedback processes complicate the effects of individual factors on the climate. One of the most pronounced feedback effects relates to the evaporation of water. It is stated that the warming by addition of long-lived GHGs such as CO2 will cause more water to evaporate into the atmosphere. Since water vapor itself acts as a GHG, the atmosphere warms further; this warming causes more water vapor to evaporate (a positive feedback), and so on until other processes stop the feedback loop. The result is a much larger greenhouse effect than that due to CO2 alone. Although this feedback process causes an increase in the absolute moisture content of the air, the relative humidity stays nearly constant or


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even decreases slightly because the air is warmer. It is argued that “this feedback effect can only be reversed slowly as CO2 has a long average atmospheric lifetime”. Clouds: Clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud. It is argued that “these details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models. Nevertheless, cloud feedback is second only to water vapor feedback” and is positive in all the models that were used in the IPCC Fourth Assessment Report. This is more seasonal and regional contrary to water vapour. But both vary with the years. However, it is an important factor in the net radiation intensity at local-regional- national levels. Lapse Rate: A subtler feedback process relates to changes in the lapse rate as the atmosphere warms. The atmosphere’s temperature decreases with the height in the troposphere. Since emission of infrared radiation varies with the fourth power of temperature, long-wave radiation emitted from the upper atmosphere is less than that emitted from the lower atmosphere. Most of the radiation emitted from the upper atmosphere escapes to space, while most of the radiation emitted from the lower atmosphere is re-absorbed by the surface or the atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere’s rate of temperature decrease with height: if the rate of temperature decrease is greater the greenhouse effect will be stronger, and if the rate of temperature decrease is smaller then the greenhouse effect will be weaker. Both theory and climate models indicate that warming will reduce the decrease of temperature with height, producing a negative lapse rate feedback [inversion effect] that weakens the greenhouse effect. The rate of temperature change with height is very sensitive to small errors in observations, making it difficult to establish whether the models agree with observations. The lapse rates are influenced by localized factors as well on solar factors. Albedo: Another important feedback process is ice-albedo feedback. When global temperatures increase, ice near the poles melts at an increasing rate. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continue. The ecological changes such as land use – land cover change (see Chapter 7) plays major role on this. Thermal inversions: This plays an important role in winter period, particularly in high latitude belt under pollution. Changes in the Ocean Currents: It is a fact that the heating or cooling of the Earth’s surface can cause changes in the Ocean currents. As the Ocean currents play a significant role in distributing heat around the Earth, changes in these currents can bring about significant changes in climate from region to region. The


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long-term systematic variations in temperature, such as glacial and interglacial periods, play an important role on this.Positive feedback due to release of CO2 4 and CH from thawing permafrost, such as the frozen peat bogs in Siberian, is an additional mechanism that could contribute to warming. Similarly a massive release 4 of CH from methane clathrates in the Ocean could cause rapid warming, according to the clathrate gun hypothesis. The Ocean’s ability to sequester carbon is expected to decline as it warms. This is because the resulting low nutrient levels of the mesopelagic zone (about 200 to 1000 m depth) limit the growth of diatoms in favor of smaller phytoplankton that are poorer biological pumps of carbon. 8.3.4 Other Factors Solar Variations: Changes occurring within (or inside) the Sun can affect the intensity of the sunlight that reaches the Earth’s surface. The intensity of the sunlight can cause either warming (for stronger solar intensity) or cooling (for weaker solar intensity). According to NASA Research, reduced solar activity from the 1400s to the 1700s was likely a key factor in the “Little Ice Age” which resulted in a slight cooling of North America, Europe and probably other areas around the globe. Some studies related to solar variations are summarized in Chapter 6. The impact of solar related factors on weather were significantly reported in a number of research papers published prior to 1980. A paper by Peter Stott and other researchers suggests that climate models overestimate the relative effect of GHGs compared to solar factor; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated. A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming. It suggests magnetic activity of the Sun is a crucial factor, which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate. One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas GHG theory predicts cooling there. The observed trend since at least 1960 has been a cooling of the lower stratosphere. Reduction of stratospheric ozone also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s. Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since. In 2006, Peter Foukal and other researchers from the United States, Germany, and Switzerland found no net increase of solar brightness over the last thousand years. Solar cycles led to a small increase of 0.07% in brightness over the last thirty years. This effect is far too small to contribute significantly to global warming. A paper by Mike Lockwood and Claus Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays. Henrik Svensmark and Eigil Friis-Christensen, the main proponents of cloud seeding by galactic cosmic rays, disputed this criticism of their hypothesis. A 2007 paper found that in the last 20 years there has been no significant link between changes in cosmic rays coming to Earth and cloudiness


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and temperature. Here, we must not forget that the effects associated solar variation have not only direct effects but also indirect effects. By integrating these two impacts that vary with the situation to situation only it is possible to determine the quantitative impact of solar variations on weather. This is clearly demonstrated in the case of solar flares impact on lower tropospheric weather. Causes of Change Prior to the Industrial Era (pre-1780): Known factors of past climate change include: Changes in the Earth’s orbit: changes in the shape of the Earth’s orbit (or eccentricity) as well as the Earth’s tilt and precession affect the amount of sunlight received on the Earth’s surface. These orbital processes — which function in cycles of 100,000 (eccentricity), 41,000 (tilt), and 19,000 to 23,000 (precession) years — are thought to be the most significant drivers of ice ages according to the theory of Mulitin Milankovich, a Serbian mathematician (1879-1958). Studies of the Earth’s previous climate suggest periods of stability as well as periods of rapid change. Long string of widespread, large and abrupt climate changes were associated with glacial periods (NRC, 2002). It is also reported that abrupt or rapid climate changes tend to frequently accompany transitions between glacial and interglacial periods (and vice versa) and thus, abrupt climate changes have occurred throughout the Earth’s history. It was noted that human civilization arose during a period of relative climate stability. During the last 2,000 years, the climate has been relatively stable. The issue of whether the temperature rise of the last 100 years crossed over the warm limit of the boundary defined by the Medieval Climate Anomaly has been a controversial topic in the science community. The National Academy of Sciences recently completed a study to assess the efforts to reconstruct temperatures of the past one to two millennia and place the Earth’s current warming in historical context (NRC, 2006). Volcanic eruptions: Volcanoes can affect the climate because they can emit aerosols and carbon dioxide into the atmosphere. Volcanic aerosols tend to block sunlight and contribute to short term cooling. Aerosols do not produce long-term change because they leave the atmosphere not long after they are emitted. According to the US Geological Survey (USGS), the eruption of the Tambora Volcano in Indonesia in 1815 lowered global temperatures by as much as 5ºF and historical accounts in New England describe 1816 as “the year without a summer.” Volcanoes also emit carbon dioxide (CO2 ). For about two-thirds of the last 400 million years, geologic evidence suggests CO2 levels and temperatures were considerably higher than present. One theory is that volcanic eruptions from rapid sea floor spreading elevated CO2 concentrations, enhancing the greenhouse effect and raising temperatures. However, the evidence for this theory is not conclusive and there are alternative explanations for historic CO2 levels (NRC, 2005). While volcanoes may have raised pre-historic CO2 levels and temperatures, according to the USGS Volcano Hazards Program, human activities now emit 130 times as much CO2 as volcanoes (whose emissions are relatively modest compared to some earlier times). These climate change factors often trigger additional changes or “feedbacks” within the climate system that can amplify or dampen the climate’s initial response to them (whether the response is warming or cooling). How? Is there any evidence on such? These


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are valid only when issues are dealt with practical data rather than theoretical/ hypothetical presumptions. Tropospheric Temperature Change: Measurements of the Earth’s temperature taken by weather balloons (also known as radiosondes) and satellites from the surface to 5-8 miles into the atmosphere also reveal warming trends. According to NOAA’s National Climate Data Centre: For the period 1958-2006, temperatures measured by weather balloons warmed at a rate of 0.22°F per decade near the surface and 0.27°F per decade in the mid-troposphere. The 2006 global midtroposphere temperatures were 1.01°F above the 1971-2000 average, the third warmest on record. For the period beginning in 1979, when satellite measurements of troposphere temperatures began, various satellite data sets for the mid-troposphere showed similar rates of warming — ranging from 0.09°F per decade to 0.34°F per decade, depending on the method of analysis (?). This range itself put doubts on the warming of troposphere. Stratospheric Temperature Change: Weather balloons and satellites have also taken temperature readings in the stratosphere. This level of the atmosphere has cooled. The cooling is consistent with observed stratospheric ozone depletion since ozone is a GHG and has a warming effect when present. It’s also likely that increased GHG concentrations in the troposphere are contributing to cooling in the stratosphere as predicted by radiative theory. It is an illogical interpretation. The major cooling effect at Antarctica zone is primarily related to the circumpolar vertex formation that obstructs the mixing of warm middle latitude air with cool polar air. That is system effect. This is clearly evident from the seasonal effects and latitudinal effect on ozone depletion, observed over both Northern & Southern Hemispheres (Chapter 2). Recent Scientific Developments: The U.S. Climate Change Science Program (CCSP) recently published a report, which addresses some of the long-standing difficulties in understanding changes in atmospheric temperatures and the basic causes of these changes. According to the report: There is no discrepancy in the rate of global average temperature increase for the surface compared with higher levels in the atmosphere. This discrepancy had previously been used to challenge the validity of climate models used to detect and attribute the causes of observed climate change. Errors identified in the satellite data and other temperature observations have been corrected. These and other analyses have increased confidence in the understanding of observed climate changes and their causes. Research to detect global warming and attribute its causes using patterns of observed temperature change shows clear evidence of human influences on the climate system due to changes in GHGs, aerosols and stratospheric ozone. An unresolved issue is related to the rates of warming in the tropics. Here, models and theory predict greater warming higher in the atmosphere than at the surface. However, greater warming higher in the atmosphere is not evident in three of the five observational data sets used in the report. Whether this is a result of uncertainties in the observed data, flaws in climate models, or a combination of


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these is not yet known. The information presented above clearly demonstrate the fact that a part of global warming is associated with human influence but this does not mean, it is associated with GHGs. The realistic estimate of the contribution of increasing GHGs on the warming is still a big question mark? Ocean Acidification: A variety of issues are often raised in relation to global warming. One is the Ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the Oceans. CO2 dissolved in the Ocean reacts with water to form carbonic acid, resulting in acidification. The Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004, and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the Ocean absorbs more CO2. Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO2 , that could disrupt food webs and impact human societies that depend on marine ecosystem services. Global Dimming: The gradual reduction in the amount of global direct irradiance at the Earth’s surface may have partially mitigated global warming in the late twentieth century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that GHGs would have resulted in more warming than observed if not for these dimming agents. The Earth’s climate has changed throughout history. From glacial periods (or “ice ages”) where ice covered significant portions of the Earth to interglacial periods where ice retreated to the poles or melted entirely the climate has continuously changed. Scientists have been able to piece together a picture of the Earth’s climate dating back decades to millions of years ago by analyzing a number of surrogate, or “proxy,” measures of climate such as ice cores, boreholes, tree rings, glacier lengths, pollen remains, and ocean sediments, and by studying changes in the Earth’s orbit around the sun. 8.4

Mitigation of Global Warming

The IPCC’s Working Group III is responsible for crafting reports that deal with the mitigation of global warming and analyzing the costs and benefits of different approaches. In the 2007 IPCC Fourth Assessment Report, they conclude that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as energy supply, transportation, industry, and agriculture that should be implemented to reduce global emissions. They estimate that stabilization of carbon dioxide equivalent between 445 and 710 ppm by 2030 will result in between a 0.6% increase and 3% decrease in global gross domestic product. According to Working Group III, to limit temperature rise to 2 0C, “developed countries as a group would need to reduce their emissions to below 1990 levels by 2020 (on the order of –10% to 40% below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40% to 95% below 1990 levels), even if developing countries make substantial reductions.”


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According to Hansen, et al. in 2007, paleoclimate data show that climate sensitivity is ~3°C for doubled CO2 , including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and icefree Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciations occurring when CO2 fell to 450 ± 100 ppm, a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on the Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The basic weakness in this argument is, during the glacial and interglacial periods, the changes in carbon dioxide was due to changes in sea/ocean surface temperatures and vice-versa is not the case as stated above. He further states that the largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350-ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects. A probabilistic analysis concluded that the long-term CO2 limit is in the range 300500 ppm for 25 percent risk tolerance, depending on climate sensitivity and nonCO2 forcings. Stabilizing atmospheric CO2 and climate requires that net CO2 emissions approach zero, because of the long lifetime of CO2 . We use paleoclimate data to show that long-term climate has high sensitivity to climate forcings and that the present global mean CO2 , 385 ppm, is already in the dangerous zone. Despite rapid current CO2 growth, ~2 ppm/year, we show that it is conceivable to reduce CO2 this century too less than the current amount, but only via prompt policy changes. A global climate forcing, measured in W/m2 averaged over the planet, is an imposed perturbation of the planet’s energy balance. Increase of solar irradiance (So) by 2% and doubling of atmospheric CO2 are each forcings of about 4 W/m2. Charney defined an idealized climate sensitivity problem, asking how much global surface temperature would increase if atmospheric CO2 were instantly doubled, assuming that slowly changing planetary surface conditions, such as ice sheets and forest cover, were fixed. Long-lived GHGs, except for the specified CO2 change, were also fixed, not responding to climate change. The Charney problem thus provides a measure of climate sensitivity including only the effect of ‘fast’ feedback processes, such as changes of water vapor, clouds and sea ice. Classification of climate change mechanisms into fast and slow feedbacks is useful, even though time scales of these changes may overlap. We include as fast feedbacks aerosol changes, e.g., of desert dust and marine dime thylsulfide that occur in response to climate change. Charney used climate models to estimate fast-feedback doubled CO2 sensitivity of 3 ± 1.5°C. Water vapor increase and sea ice decrease in response to global warming were both found to be strong positive feedbacks,


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amplifying the surface temperature response. Climate models in the current IPCC assessment appears to agree with Charney’s estimate. Climate models alone are unable to define climate sensitivity more precisely, because it is difficult to prove that models realistically incorporate all feedback processes. The Earth’s history, however, allows empirical inference of both fast feedback climate sensitivity and long-term sensitivity to specified GHG change including the slow ice sheet feedback. However, here one must be cautious in deciding “cause and effect” factors. Large fluctuations in the size of the Antarctic ice sheet have occurred, possibly related to temporal variations of plate tectonics and outgassing rates. The relatively constant atmospheric CO2 amount of the past 20 My implies a near balance of global outgassing and weather rates over that period. Knowledge of Cenozoic CO2 is limited to imprecise proxy measures except for recent ice core data. There are discrepancies among different proxy measures, and even between different investigators using the same proxy method. Nevertheless, the proxy data indicate that CO2 was of the order of 1000 ppm in the early Cenozoic but <500 ppm in the last 20 My – we must keep in mind that these are indirectly derived!!! The entire Cenozoic climate forcing history is implied by the temperature reconstruction, assuming a fast-feedback sensitivity of ¾°C per W/m2. Subtracting the solar and surface albedo forcings, the latter from ice sheet area vs. time 8.5

Global Warming!!!

Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C during the twentyfirst century. The range of values results from the use of differing scenarios of future GHG emissions as well as models with differing climate sensitivity. From these they expressed that warming and sea level rise are expected to continue for more than a thousand years even if GHG levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the Oceans. They further postulated that increasing global temperature will cause sea level to rise, and is expected to increase the intensity of extreme weather events and to change the amount and pattern of precipitation; changes in agricultural yields, trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors. Global average temperature has increased by 0.75 °C (1.35 °F) relative to the period 1860–1900. It is also reported that since 1979, land temperatures have increased about twice as fast as the Ocean temperatures (0.25 °C per decade against 0.13 °C per decade). Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.


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The observed surface global & hemispheres average temperature patterns (Figure 8f) show cooler in the Southern Hemisphere with less land area compared to Northern Hemisphere. Figure 8g presents the satellite & upper air balloon global average temperature data series. The satellite data series cover both land and Ocean areas as presented by NASA for the past two decades did not indicate rise in the global surface temperatures & the upper air balloon observational data followed in between the satellite and surface observations (Reddy, 2007a). It appears that the satellite data series were modified latter!!! The average global surface observed data presented a rise that too in a modulated form presenting ups-anddowns (Figure 8f), which is not seen in model predicted temperature pattern (Figure 8a) or in carbon dioxide data series (Figures 8b). This means, the current climate models neither produce a good match to observations of global temperature changes over the last century nor simulate all aspects of climate. These models do not unambiguously attribute the warming that occurred from around 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made GHG emissions but far from observed pattern, which means the models lack clarity on the influence of GHGs on temperature raise. A recent report issued by the U.S. Climate Change Science Program concluded that over the 25-year satellite record, the surface and mid-troposphere have both warmed by approximately 0.15°C per decade – contrary to earlier presentation (Figure 8g) —. Global warming deniers had frequently challenged the reality of human-induced global warming and the reliability of climate models by citing previously reported discrepancies between the amounts of warming at the surface compared to the amount of warming higher in the atmosphere. The original discrepancies were reported by John Christy, Roy Spencer and their team at the University of Alabama-Huntsville based on microwave emissions from the atmosphere recorded by satellites. But this argument is invalidated once errors in satellite and radiosonde data have been identified and corrected; and new temperature time series for the surface and atmosphere are consistent with each other. The University of Alabama-Huntsville team also acknowledged their previous errors in late 2005. This reconciliation of previous discrepancies led to an article in Science titled “No Doubt About It, the World is Warming.” At an international tropical meteorology conference in India, such a scene was repeated – the group engaged in the collection of satellite data said that we are still in the process of working out to put the data in right perspective but another group presented results in practical perspective inferring great things. In the conference I put the question, then who is correct and who is wrong but both the groups kept quite. That is if it is not serving their purpose or not fitting into their models, they manipulate data. It is very difficult to prove who is correct!!! This is rarely possible in the observed surface data. Any manipulations can be easily detected. A study by David Douglass, John Christy, Benjamin Pearson and Fred Singer comparing the composite output of 22 leading global climate models with actual climate data finds that the models do not accurately predict observed changes to


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the temperature profile in the tropical troposphere. The authors note that their conclusions contrast strongly with those of publications based on essentially the same data. It is argued that the detailed causes of the recent warming remain an active field of research. IPCC is simply thrusting on the world community some thing that is not scientifically proved beyond doubt. Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity. None of the effecting factors are instantaneous. As with any field of scientific study, there are uncertainties associated with the global warming. This does not imply that scientists do not have confidence in many aspects of climate science. Some aspects of the science are known with virtual certainty, because they are based on well-known physical laws and documented trends. Current understanding of many other aspects of climate change ranges from “very likely” to “uncertain”. Remaining scientific uncertainties include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the Globe; most national governments have signed and ratified the Kyoto Protocol aimed at reducing GHG emissions. It was noted that even if GHGs were stabilized at 2000 levels, a further warming of about 0.5 °C would still occur!!! Important scientific questions remain about how much warming will occur, how fast it will occur, and how the warming will affect the rest of the climate system including precipitation patterns and storms. Answering these questions will require advances in scientific knowledge in a number of areas, namely improving understanding of natural climatic variations, changes in the Sun’s energy, land-use changes, the warming or cooling effects of pollutant aerosols, and the impacts of changing humidity and cloud cover; determining the relative contribution to climate change of human activities and natural causes; projecting future GHG emissions and how the climate system will respond within a narrow range; improving understanding of the potential for rapid or abrupt climatic change; etc. Finally it is essential to present the realistic numerical impact of GHGs on temperature!!! Additionally (from IPCC, 2007) that “The warming trend is seen in both daily maximum and minimum temperatures, with minimum temperatures increasing at a faster rate than maximum temperatures. Land areas have tended to warm faster than the Ocean areas and the winter months have warmed faster than summer months. Widespread reductions in the number of days below freezing occurred during the latter half of the 20th century in the United States as well as most land areas of the Northern Hemisphere and areas of the Southern Hemisphere. Average temperatures in the Arctic have increased at almost twice the global rate in the past 100 years”. These observations, when looked in the meteorological context present a different cause for the increase in night temperatures (minimum temperature) such as heat island effect..


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It is reported that the sea temperatures increase more slowly than those on land both because of the larger effective heat capacity of the Oceans and because the Ocean can lose heat by evaporation more readily than the land. The Northern Hemisphere has more land than the Southern Hemisphere, so it warms faster. The Northern Hemisphere also has extensive areas of seasonal snow and sea-ice cover subject to the ice-albedo feedback. More GHGs are emitted in the Northern Hemisphere than Southern Hemisphere. It is stated that this does not contribute to the difference in warming because the major GHGs persist long enough to mix between hemispheres. However, the network and accuracy of surface data are quite different in the two hemispheres and yet not many differences are noted in the temperature trend. Based on estimates by NASA’s Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree. Estimates prepared by the WMO and the Climate Research Unit concluded that 2005 was the second warmest year, behind 1998. Temperatures in 1998 were unusually warm because the strongest El Nino in the past century occurred during that year. It is also reported that since the mid 1970s, the average surface temperature has warmed about 1°F. The Earth’s surface is currently warming at a rate of about 0.32ºF/decade or 3.2°F/century. The eight warmest years on record (since 1850) have all occurred since 1998, with the warmest year being 2005. Anthropogenic emissions of other pollutants—notably sulfate aerosols— can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century, though the cooling may also be due in part to natural variability. James Hansen and colleagues have proposed that the effects of the products of fossil fuel combustion—CO2 and aerosols—have largely offset one another, so that warming in recent decades has been driven mainly by non-CO2 GHGs. Paleoclimatologist William Ruddiman has argued that human influence on the global climate began around 8,000 years ago with the start of forest clearing to provide land for agriculture and 5,000 years ago with the start of Asian rice irrigation. Ruddiman’s interpretation of the historical record, with respect to the methane data, has been disputed. The methane vs carbon dioxide issue in global warming took political overtones of developed vs developing world. From these it is clear that the global warming theory put forth by IPCC under the disguise of “majority” theory needs re-look. IPCC must come up with the facts that how much of the global warming is due to anthropogenic greenhouse gases and how much is due to causes in built in nature & others. This does not mean that we must encourage release of greenhouse gases into the atmosphere. But it is to say that we must not look at western system of lopsided argument but look at developing countries stand point where the direct impact of these pollutants on life-forms. Give top priority in controlling pollution that have direct impact on health of life-forms. This has serious repercussions on the poverty eradication


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system in developing countries with high population pressure with low infrastructure facilities. 8.6

Exploitation on the name of GW!!!

This is dealt in terms of agriculture as an example, which is vital issue in developing countries to meet their food & other needs. Using global warming as a means to exploit developing countries agriculture is in a critical stage. Unless the exploitation is stopped now, this may through the developing countries economy in doldrums. Let us see how to stop this. Each agricultural species has an area of geographical adaptation where its’ climatic requirements are best met. The limits vary according to individual species. Individually or in combination the environmental factors produce significant changes in a biological cycle, which may be either detrimental or beneficial. The two biological processes that are influenced by weather parameters are crop development and growth. Sometimes these processes are hindered by unusual factors such as insects/pests/diseases on the one hand and frost, hail, floods, strong winds, excess radiation or temperature, cyclones, manmade factors on the other. These by their intensity may cause death of the species and their frequency renders its cultivation uneconomical. The former type again relates to weather/climate on the one hand and the soil on the other. That is, weather influences the degree of interaction between crop and insects/pests/diseases. Reddy (1993) presented a review of models related to the estimation of crop development and crop growth. The two important continuous and periodic elements that affect development are temperature and photoperiod. In addition to these two, relative humidity — atmospheric dryness, soil humidity – soil dryness (related to soil moisture, soil temperature, soil type), soil fertility, plant – population & agronomic practices, etc —, affect the crop development and thereby crop growth. Here through proper selection/breeding the temperature and photoperiod factors can be manipulated to a maximum extent (Reddy, et. al., 1984]. The basic weakness in whole of this exercise is in relation to expected global warming and its’ consequent impacts but failed to take note of “even if there is no global warming there is an absolute high risk to life farms on the Earth due to direct impact of the pollution & pollutants, that costs billions of US# even at short-term, leave alone the long-term impacts”. Unfortunately, IPCC is engaged in this destructive mode and it is the duty of individual nations to look in to this angle of climate change. Under these circumstances the middlemen-the corporate giants are exploiting the third world countries. Gene Giants Grab “Climate Genes”: Amid Global Food Crisis, Biotech Companies are exposed as Climate Change Profiteers. A report released by Canadian-based civil society organization, ETC Group, reveals that the world’s largest seed and agrochemical corporations are stockpiling hundreds of monopoly “patents” on genes in plants that the companies will market as crops genetically engineered to withstand environmental stresses associated with climate change - including drought, heat, cold, floods, saline soils, and more. ETC Group’s report warns that - rather than a solution for confronting


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climate change - the promise of so-called “climate-ready” crops will be used to drive farmers and governments onto a proprietary biotech platform. “In the face of climate chaos and a deepening world food crisis, the ”Gene Giants” are gearing up for a PR offensive to re-brand themselves as climate saviors,” says Hope Shand, Research Director of ETC Group. “The companies hope to convince governments and reluctant consumers that genetic engineering is the essential adaptation strategy to insure agricultural productivity. Monopoly control of crop genes is a bad idea under any circumstances - but during a global food emergency with climate change looming - it’s unacceptable and must be challenged.” According to ETC Group’s report, Patenting “Climate Genes”...And Capturing the Climate Agenda, Monsanto, BASF, DuPont, Syngenta, Bayer and Dow - along with biotech partners such as Mendel, Ceres, Evogene and more - have filed 532 patent documents on genes related to environmental stress tolerance at patent offices around the world. A list of 55 patent families (subsuming the 532 patent grants and applications) is appended to the report. “The emphasis on genetically engineered, so-called ‘climate-ready’ crops will divert resources from affordable, decentralized approaches to cope with changing climate. Patents will concentrate corporate power, drive up costs, inhibit independent research and further undermine the rights of farmers to save and exchange seeds,” explains Shand. “Globally, the top 10 seed corporations already control 57% of commercial seed sales. This is a bid to capture as much of the rest of the market as possible.” ETC Group calls on governments at the UN Biodiversity Convention (CBD) in Bonn, Germany to suspend immediately all patents on so-called “climate ready” crop genes and traits. We also call for a full investigation, including the social and environmental impacts of these new, un-tested varieties. Further, governments meeting in Bonn should identify and eliminate policies such as restrictive seed laws, intellectual property regimes, contracts and trade agreements that are barriers to farmer plant breeding, seed saving and exchange. “The world has already recognized that we are in a food crisis and a climate ‘state of emergency,’” notes Pat Mooney, ETC Group’s Executive Director. “In this ‘state of emergency’ farmers must be given all the freedom and resources they need to get us through this crisis,” Mooney adds. According to ETC Group, many of the patent claims are unprecedented in scope because a single patent may claim several different environmental (abiotic) stress traits. In addition, some patent claims extend not just to abiotic stress tolerance in a single engineered plant species - but also to a substantially similar genetic sequence in virtually all engineered food crops. The corporate grab extends beyond the U.S. and Europe. Patent offices in major food producing countries such as Argentina, Australia, Brazil, Canada, China, Mexico and South Africa are also swamped with patent filings. Monsanto (the world’s largest seed company) and BASF (the world’s largest chemical firm) have entered into a colossal $1.5 billion partnership to engineer stress tolerant plants. “Together,” adds Kathy Jo Wetter of ETC Group, “the two companies account for nearly half of the patent families related to engineered stress tolerance identified by ETC Group. If we


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include their smaller biotech partners like Ceres and Mendel, Monsanto and BASF have a part in almost two-thirds of the so- called ‘climate-ready’ germplasm”. “Technological silver bullets - especially patented ones - will not provide the adaptation strategies that small farmers need to survive in the face of climate change,” says ETC Group’s Jim Thomas. Climate scientists predict that marginalized farming communities in the global South - those who have contributed least to global greenhouse emissions - are among the most severely threatened by climate chaos created by the world’s richest countries. “The South is already being trampled by the North’s super-sized carbon footprint. Will farming communities now be stampeded by the Gene Giants’ climate change profiteering? “ asks Thomas. For the Gene Giants, the focus on “climate genes” is a golden opportunity to push genetically engineered crops as “green” and climate-friendly. Biotech seeds will no longer be marketed as a choice, but as a necessity. Given the state of emergency in food and agriculture, governments will be pressured to overlook biosafety regulations and to accept dangerous technologies such as Terminator that have been rejected by the international community. (Despite a U.N. moratorium on Terminator seeds, the biotech industry argues that genetic seed sterilization will make biotech crops safer by containing gene flow from engineered crops and trees. The basic question now to be answered is: What to be the solution to counter this trend of Geni-Gaints conspiracy of “patenting”? Here are some points that were submitted to Hon’ble Prime Minister of India: This year the country is facing unprecedented shortages in food supply. The basic question that arises is: Why? And how to stop such recurrences in future? Around 60% of the population in India still depends upon “directly or indirectly” on agriculture. More than 60% of Indian agriculture is at the mercy of “Rain God”. Lacks of acres of fertile agriculture lands are/were affected by pollution & indiscriminately allocation to SEZs, as against the laws. The “floods and droughts” are common every year in one part of the country or the other integrated with climatic cycles in Indian rainfall. With the ever-increasing population, disproportionate to our agricultural production, the food needs are increasing with new lifestyle in which dry-land crops suffered a lot, which are the staple food of millions from centuries. Farmers are looking at high risk-cash crops, which is a bad “cropping pattern practices” against the local prevailing conditions. This year, due to un-seasonal rains farmers suffered severe monetary losses as well thus, causing shortages in food grains due to lack of storage & drying facilities. The 1960s green revolution technology was based on few years experience of a few scientists, interwoven with the vested interests of few Western MNCs created new problems hitherto unknown and thus affecting environment – soil & human, animal, plant life and health – and increased the cost of production. All these factors were not accounted into production costs. Though the Indian agriculture has grown by leaps and bounds in quantity but failed to achieve the quality of traditional food. To understand this fallacy in green revolution technology,


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it took forty years. This technology was successful under irrigation, projects developed at huge costs. The main beneficiaries of this system were the MNCs involved in the chemical inputs trade under high subsides, the other major input in to the technology. Even with all these ill affects, the production growth curve has flattened after around 1984. This is basically because; Western/MNCs interests cloud our scientists and scientific institutions. Our Academies of sciences are under the control of the same groups. The top bosses, after retirement joining them. Most unfortunately, the farmers’ federations also joined this bandwagon harming the agriculture environment through helping the illegal testing of unapproved hazardous technologies in farmers’ fields. In this, our bureaucrats are also not far behind the scientific community (Reddy, 2006a). The success of green revolution was possible with irrigation, as the diffusion of Technologies was possible only through irrigation. Because of this the rainfed agriculture has not recorded the success as that was recorded in irrigated agriculture with the stagnation in irrigation potential but increased the level of risk. Thus, the gulf between the irrigated agriculture and rainfed agriculture is increasing and this is amplified through step motherly treatment for rainfed food grains under subsidized schemes of PDS, where rice is supplied neglecting coarse grains produced under rainfed condition. This is one other reason for food shortages. Area under bio-fuel is not an important issue like in Mexico, as fertile lands are not used for this purpose but aquaculture is an important issue in India as fertile lands are under destruction. The other important issue is the destruction of forestlands is in rampant and cause the reduction in rainfall with increased temperature regimes. Thus, water requirements of crops are increasing. We are not utilizing available water resources effectively due to inter-state disputes along with vested interest groups creating legal disputes. The four main Western MNCs minted billions of US$ through the sale of chemical inputs under the disguise of green revolution technology have come up with a new technology, known as genetically modified seed technology that works under the same conditions as that of green revolution as they are no more gaining with green revolution technology. Scientists like Noble prize winner Dr. Norman Borlaugh, who is behind the green revolution technology, now writes letters to Indian scientists in support of genetically modified crops stating that this is the technology to over come the poverty as an agent of Western MNCs, Indian retired scientists who have the clout with government in turn planted these letters in Indian media. When the entire world was against the Terminator Technology, the former D.G. of ICAR, Dr. R. S. Paroda said that it is a good technology to eradicate Parthanium, entered India with PL-480 Wheat. This is like “Scratching the head with Fire”. Biotechnology companies often claim that GM organisms are essential scientific breakthroughs needed to feed the World, protect the environment, and reduce poverty in developing countries. Unfortunately, our own agriculture top boss, the ICAR D.G., Dr. Mangal Roy, echoes this at a biotechnology meet organized by FICCI in New Delhi on 16th September 2007. At the same time he argues that


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GM food has more resistance power in humans against diseases as well require less chemical fertilizers & less water. This is exactly opposite to what the scientific out come in India and elsewhere in the world including in USA. Most of the innovations in agricultural biotechnology have been profit-driven rather than need driven. The real thrust of the GM industry is not to make third world agriculture more productive, but rather generate profits. These technologies respond to the need of biotechnology companies to intensify farmers’ dependence upon seeds protected by the so-called “IPR”, which conflict directly with age-old rights of farmers to reproduce or store seeds. Still there are many unanswered ecological questions – bio-safety, food safety, ethical, etc aspects — regarding the impact of transgenic crops. The green revolution technology created health hazards to life forms hither to unkown through food, water, soil & air pollution. To cure these diseases established highly polluting [soil, air & water] industries that created new diseases. The vicious circle is moving with increased population & changed life style. This area of creating GHGs is not received as much as that of power production. Here, developed countries are polluting developing countries by encouraging out sourcing production. Here think globally and act locally plays the major role but unfortunately, the slogan adopted is “think locally and act globally”. Some powerful MNCs are vigorously trying to bring in corporate agriculture. As a prelude to this they are behind the price rise through encouraging hording, illegal export, etc. Opposition political parties also joined this bandwagon. A media report says that thousands of tons of rice is exported illegally; farmers are not able to get Rs. 3 per kg for onions but in the market they are fetching Rs. 17 per kg. That is artificial shortage is another part of the price rise game. The research priorities of government sponsored agriculture research institute such, as CSIR must change to meet the local needs of the farmers and to make Indian Agriculture Sustainable. At present they are carrying out the tasks what their Western bosses/MNCs wanted them to do!!! Because of this tendency of our research Institutions in India made the glut in Indian Agriculture. Prior to green revolution the farmers used indigenous technologies evolved over hundreds and thousands of years experience and passed it on to generation after generation. These technologies were weather & soil based farming systems that include crops & cropping pattern, agricultural practices, land & water management practices. These are said to be “Golden Days” in the history of Indian farming. No pollution, no worry about seed adulteration, fertilizer adulteration as they used the good grain as seed and compost of farmyard manure as fertilizer. Though the yields are low, the quality of food was excellent. However, progressive farmers over different parts of the country have shown that they can achieve yields better than the high cost green revolution yields with traditional agriculture. Also, all over India different research groups working with farming community have shown that this is possible with organic farming. (1) Firstly, our research institutions must collect the inventions of progressive farmers and integrate them in to the agriculture system and propagate;


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Co-operative farming: In Indian agriculture conditions, more than 90% of farmers are within the 5 ha of cultivated area group and constitute more than 60% of the cultivated area. Only around 40% of cultivated area receives irrigation and in this, 15 to 20% area gets water from dwindling groundwater sources by which the cultivated area per pump has gone down dramatically and will continue as recharging venues are being destroyed. These farmers face the major problem of adulteration of seed, chemical inputs, loans, selling & storing the outputs, etc. Now, to improve the condition of such farmers, the only way left under the present socio-economicpolitical-bureaucratic scenario, is to group the farmers into co-operative farming groups. Such system help in the effective utilization of water & energy resources, input resources, subsidies/loans by government agencies and develop an effective mechanism for sale and storage agriculture outputs. They can produce their own seed and organic inputs and thus the cost of production could be reduced drastically and thus improve the economy of the farmers and eliminate farmers suicides. Here the groups can control the crops/cropping system or farming system that better suits the prevailing conditions. In fact under the present conditions lacks of crores given every year under loans, subsidies, and loans viewer system are going into drain. To utilize them effectively, the only solution is co-operative farming. Also this is the only way to stop farmers’ suicides. The problem must be talked in an integrated manner rather than in isolation. This is possible under co-operative farming. (2) Secondly, adapt, under marginal, small and semi-medium farming sectors, the system of co-operative farming under rainfed as well under well irrigation with micro-irrigation system. This can be implemented through local MLAs & MPs; Corporate agriculture is not a solution: Our bureaucracy is influenced by the rich multinational companies and put forward the corporate farming as a solution to food production to meet the growing population forgetting that the agriculture is providing employment to more than 65% of population, directly and indirectly. In fact the foundations were laid for such a system during the previous regime itself. At present to some extent prices are under the control of government and once the corporatism enter the scene the prices will be at their mercy that leads severe poverty and mass suicides. (3) Avoid Corporate Farming, which is a bad practice to the Indian agriculture system; Others • Adapt farming systems practices to reduction of weather related risks and those that better utilization of water resources; • In the public distribution system (PDS) encourage giving coarse cereals at the same level of subsidies as that of rice; • Tank irrigation: To get a balanced growth at local and regional levels under the prevailing climate & weather conditions top priority must be given to protect and restore the areas under tank irrigation. This shall not only help the direct


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irrigation but also improve indirect irrigation through wells/ bore-wells through recharging-dwindling ground water. Watersheds and cloud seeding are futile exercises and waste of public money in dry-areas of India with erratic & undependable rainfall patterns. However, the government must complete irrigation projects by clearing inter-state/judicial tangles. In agriculture sector the wasteful expenditure to exchequer is too many that are sufficient to complete the irrigation projects. [4]. Give the responsibility of protecting and maintaining of tanks to the local MLAs & MPs; • Seed village programmes could be effectively implemented through establishment of commodity boards for region specific important crops by linking this with State Seed Corporation. It is clear that the basic approach used in the global warming is to help multinational western companies to mint money. To achieve this goal, IPCC became a pawn in the hands of MNCs & Western rich nations. Developing countries must not enter into this trap and should focus “think globally and act locally” to minimize the health hazards and through which pollution & GHG could be minimized. This is the best solution for developing countries to sustain the agriculture growth.


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Chapter 9

Extreme Weather & Climate Events 9.1

Introduction

A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as that of the Larsen Ice Shelf, Sea Level Rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events, are being attributed in part to global warming. One study predicts 18% to 35% of a sample of 1,103 animals and plant species would be extinct by 2050, in relation to future climate projections. Based on such reports, “India Today” magazine in its’ August 12, 2002 issue under cover story by Raj Chengappa reports mind boggling headlines, such as: “This year’s wayward monsoon over India and freaky weather elsewhere portend devastating climate changes as a result of global warming; Glaciers in the Himalayas will recede by 2020 causing floods and then deserts; By 2015 rise in sea levels will drown parts of Mumbai. Loss is Rs. 2,28,700 crore; Productivity of rice and wheat crops will drop by 15 per cent in the next decade; Warmer climate will cause major health problems such as the spread of dengue; All nations will be hit. The US will be a dust bowl and Bangladesh will be swamped; etc”. By this way fear psychosis is built in human mind and get hype. 9.2

Glacier Melting

It is a well-known fact that in the Hydrological Cycle (Figure 9a), the evaporated water from Oceans that occupies two-thirds of globe and water bodies comes back as rain & snow. Some of the processes involved in this cycle are briefly given as: • Evaporation is the change of state of water (a liquid) to water vapour (a gas). On an average, about 47 inches (120 cm) is evaporated into the atmosphere from the Ocean each year; • Transpiration is evaporation of liquid water from plants and trees into the atmosphere. About 90% of all water that enters the roots transpires into the atmosphere; • Sublimation is the process where ice and snow (a solid) change into water vapour (a gas) without moving through the liquid phase; • Condensation is the process where water vapour (a gas) changes back in to water droplets (a liquid). This is when we begin to see clouds; • Transportation is the movement of solid, liquid and gaseous water through the atmosphere. Without this movement, the water evaporated over the Ocean would not precipitate over land; • Precipitation is water that falls to the Earth. Most precipitation falls as rain but includes snow, sleet, drizzle, and hail. Around 313,000 mi3 (515,000 km3) of water falls each year, mainly over the Ocean;


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• Runoff is the variety of ways of which water moves over the Earth’s surface. This comes from melting snow & rain; • Infiltration is the movement of water into the ground from the surface. Groundwater flow is the flow of water underground aquifers. The water may return to the surface in springs or eventually seep into the Oceans. Plant uptake is water taken from the ground water flow and soil moisture. Reports suggest that each year about 8 mm of water from the entire surface of the Oceans goes into the Antarctica and Greenland ice sheets as snowfall. If no ice returned to the Oceans, sea level would drop by 8 mm every year. Although approximately the same amount of water returns to the Ocean in icebergs and from ice melting at the edges, scientists do not know which is greater – the ice going in or the ice coming out. Reports also present that if all glaciers and ice caps melt, the projected rise in sea level will be around 0.5 m. If the melting includes the Antarctica and Greenland ice sheets, then the rise is more drastic 68.8 cm. Climate changes during 20th Century are estimated from modeling studies. Estimates suggest that Greenland and Antarctica have contributed 0.0 to 0.5 mm/ year over the 20th Century as a result of long-term adjustment to the end of the last ice age. It is reported, “sparse records indicate that glaciers have been retreating since the early 1800s”. In the 1950s measurements began that allow the monitoring of glacial mass balance. The Times of India on March 22, 2008 presented two reports with the headings “Himalayan tragedy awaits India and China, says study: Food crisis looms large as rivers like Ganga & Yangtze may dry up” and “Gangotri shall live from here to Eternity: Leading Indian scientists take a dim view of doomsayers who predict the glacier that feeds the sacred Ganga will disappear due to global warming in the next 40 years”. The first report is based on an article of Lester Brown, who said “Mountain Glaciers in the Himalayas and on the Tibet-Qinghai Plateau are melting and could soon deprive the major rivers of India and China of the ice melt needed to sustain them during the dry season. In the Ganges, the Yellow River and the Yangtze river basins, where irrigated agriculture depends heavily on rivers, this loss of dry season flows will shrink harvests”. Brown also referred in his article the IPCC report that Himalayan Glaciers are receding rapidly and that many could melt entirely by 2035. If the giant Gangotri Glacier that supplies 70% of the Ganges flow during the dry season disappears, it warned, the Ganges could become a seasonal river, flowing during the rainy season but not during the summer dry season when irrigation water needs are greatest”. The Ganga is the largest source of surface water irrigation in India and the leading source of water for the 407 million people living in the Gangetic basin, a population larger than any other single country other than China. The Yellow River and Yangtze basins hold a similar position in China. In the second report, contrary to what prophets of doom contend, that Gangotri will disappear in the next 30 to 40 years, some of India’s leading scientists


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believe there’s no immediate or even medium term threat to the glacier that feeds on of India’s greatest river, Ganga. India has 9575 glaciers, of which around 50 are being monitored by the Geological Survey of India (GSI) on a regular basis. None of these show a particularly high rate of retreat. Gangotri’s draw down – 20 meters per annum in the ‘70s – is now mere six meters a year. Bhagirath Khadak in the Himalayas was retreating at 12 m annually but last year it didn’t retreat at all. Machol in Jammu & Kashmir has showed no change since 1957. It is true of Siachen and Kagriz in Ladakh, according to Geological Survey of India (GSI), V.K. Raina, Chairman, Monitoring Committee on Himalayan Glaciology, Government of India, at a conference in Lucknow University recently says that there was no reason to press panic button based on Western analysis of melting Arctic glaciers. He also further states that the Western estimates are true for regions around the North Pole – but these glaciers open into the sea. In India, glaciers are situated over 3500 m above the sea level. The Himalayas, in fact, are conductive for the preservation of glaciers. Even if Gangotri retreats at 20 m per annum, it will last for 1,500 years. He further states that the doomsayers have based their claims of a much shorter life of Gangotri on the basis of reduction in discharge of water from the glacier into the Ganga, but glacier contributes only 25% to river discharge – the remaining 75% depends on snowfall and rain water. In fact the discharge in to Ganga increased in 2001 when there was heavy snowfall. Same is the case for this year. Dhruv Sen Singh, who teaches geology at Lucknow University and who was part of India’s first scientific expedition to the Arctic in 2007 said, “Not only the rate of retreat of Gangotri has decreased, in Leh, 123 years of temperature data shows a cooling of 0.04 degrees per decade”. He adds that the 20 m rate of retreat of Gangotri in the ‘70s wasn’t because of warming but because of the cracking in the linear structure of the glacier at the snout. Then some of its tributaries had become inactive and were contributing water instead of ice. These factors keep changing in the natural course leading to fluctuation in the rate of retreat of high mountain glaciers. In March 2006, Science magazine led with the cover “Climate Change — Breaking the Ice.” The edition included articles covering important new research on warming at both poles that is leading to changes in the ice system. These changes are occurring faster than previously observed or expected, therefore indicating that both the Arctic and Antarctic may be approaching a “tipping point” after which dangerous transformations will become unavoidable. Markers of such changes are visible in Greenland and in the Antarctic ice sheet, both of which are melting and thinning more rapidly than in the past. Velicogna and Wahr found that the mass of the Antarctic ice sheet has decreased significantly since 2002. A similar rapid loss of ice mass has been shown in the Arctic, where Rignot and Kanagaratnam found that the loss of mass from the Greenland ice sheet doubled between 1996 and 2005 to 224 ± 41 cubic kilometers (54 ± 10 cubic miles) per year. For comparison, the city of Los Angeles uses 1 cubic kilometers (0.23 cubic miles) of water per year.


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Records of past ice-sheet melting indicate that the rate of future melting and the related sea-level rise could be faster than widely thought, according to Overpeck et al. This recent study found that during the last interglacial period approximately 130,000 to 127,000 years ago, sea level ranged from 4 meters to more than 6 meters higher than today. Climate models project that by 2100, the high northern latitudes will be as warm, or warmer, than they were during the last interglacial period. Unless we curb heat-trapping emissions, temperatures in the late 21st century would be warm enough to melt at least large portions of Greenland and quite probably portions of West Antarctica. Millions of people would be vulnerable to flooding and displacement from the resulting sea level rise, and the economic loss associated with coastal inundation would be devastating. Another study looked at the link between melting ice fields and rising sea levels. Otto-Bliesner et al. quantified what melting from Greenland and other Arctic ice fields contributed to sea level rise during the last interglacial period. They evaluated ice cap retreat by analyzing results from a global climate model, a dynamic ice sheet model and paleoclimatic data. They found that melting in the western Arctic ice fields and Greenland contributed between 2.2 meters and 3.4 meters of sea level rise during the last interglacial period. While this was due to natural variations in global climate, human-induced global warming over the next century could lead to similar, substantial impacts on the polar environment. Another report says, “But it’s not just the ice system that is changing. Changes in the permafrost, or the permanently frozen ground, also reflect a warming trend in the Arctic”. Recent runs of the National Center for Atmospheric Research’s Community Climate System Model project that under business-as-usual greenhouse gas emission scenarios, there will be an up to 80 percent decline in near-surface permafrost by 2100. Even if the extent of permafrost melt is not as large as projected by this scenario and model, these results imply that large-scale changes in permafrost will occur in the future. If large-scale permafrost melting occurs, it may result in the rapid release of large quantities of methane, a potent global warming pollutant. A report says, “Scientists at the National Snow and Ice Data Center released results showing that March 2006 had the lowest Arctic wintertime sea ice coverage since 1979, the beginning of the satellite record. March sea ice represents the maximum cover for the year, and the record low in 2006 is particularly significant since it illustrates that for two years running, Arctic sea ice has failed to recover to its previous maximum levels during the winter months. The long-term mean March sea ice extent is 6.06 million square miles, whereas 2005 and 2006 set two new “record” lows at 5.72 million square miles and 5.60 million square miles, respectively. Compared to the long-term average wintertime sea ice level, the 2006-drop is approximately equivalent to three times the area of California. Although the decline in winter sea ice — the annual maximum — is not as pronounced as that of summer sea ice decline — the annual minimum — low winter sea ice means that the ice is freezing later in the fall and growing at a slower pace during the winter. We can expect this summer to continue the trend of all-time lows in sea ice extent. In fact, a study by Stroeve et al. recently found that four out of the five


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lowest years of sea ice coverage have occurred since 2002. This accelerated decline in summertime sea ice led Overpeck and his colleagues to conclude that the Arctic could be completely free of summer sea ice well before the end of this century, a state that has not occurred over at least the last million years”. New research from multiple groups suggests that current climate models may underestimate global warming projections because of a failure to account for positive feedback. For instance, higher temperatures may lead to increased releases — or reduced uptake of — carbon dioxide and/or methane by the Ocean, forests and soils. This self-reinforcing cycle may not be fully accounted for in climate models, and until recently, few studies tried to quantify it. Torn and Harte have now found that by incorporating the carbon dioxide and methane positive feedback, the warming associated with doubling of carbon dioxide due to human activities is amplified from the range of 1.5 - 4.5°C to 1.6 - 6.0°C. Similarly, Scheffer and his colleagues found that the century-scale positive feedback of rising temperatures on atmospheric carbon dioxide concentrations will further enhance warming by an extra 15 to 78 percent. Although both groups of researchers recognize the limitations and uncertainties of their projections, their independent results, which use different methods, suggest that warming over the coming century may in fact be greater than recent trends and could be larger than that projected by the Intergovernmental Panel on Climate Change. Additional studies found evidence that feedback mechanisms have amplified warming in the past. The Arctic Coring Expedition analyzed sediments from the Palaeocene/Eocene thermal maximum and found that polar temperatures during this period were more than 18°F warmer than those predicted by current climate models and that the Arctic is capable of warming to over 73°F and becoming ice free. This illustrates that higher-thanmodern greenhouse gas concentrations must have operated in conjunction with additional feedback mechanisms, currently unaccounted for in climate models, to intensify warming. Sluijs and his colleagues suspect that polar stratospheric clouds and hurricane-induced ocean mixing could have lead to the highlatitude warming and tropical cooling found in the records. However, with all these contradicting findings, the glacier melt theory do not, in fact, take into account the intensity of stress created by human activities undertaken at these sources in the name of research, pilgrimage, tourism, sports and other visits as well due to war related activities in addition to natural calamities and natural rhythm that is present in nature, impact of Earthquakes, volcanic eruptions, landslides, impact of outer space objects falling, etc. Thus the research in this area is biased/flawed towards global warming giving minimal importance to other factors. This needs rectification to get correct picture on glacial retreat due to global warming by separating the effect of other factors on glacial retreat. This aspect is researched very little!!! Also during glacial and interglacial periods the increase or decrease in carbon dioxide concentrations in the atmosphere as revealed from the paleoclimatological studies, primarily an after effect of increase or decrease in temperature pattern and not vice-versa like the anthropogenic theory.


9.3

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Sea Level Rise

As per the IPCC (2007), “sea levels are raising worldwide and along much of the U.S. coast. Tide gauge measurements and satellite altimetry suggest that sea level has risen worldwide approximately 4.8-8.8 inches (12-22 cm) during the last century. A significant amount of sea level rise has likely resulted from the observed warming of the atmosphere and the Oceans. The primary factors driving current sea level rise include: the expansion of Ocean water caused by warmer Ocean temperatures melting of mountain glaciers and small ice caps (to a lesser extent) melting of the Greenland Ice Sheet and the Antarctic Ice Sheet. Other factors may also be responsible for part of the historic rise in sea level, including the pumping of ground water for human use, impoundment in reservoirs, wetland drainage, deforestation, and the melting of polar ice sheets in response to the warming that has occurred since the last ice age”. Considering all of these factors, scientists still cannot account for the last century’s sea level rise in its entirety. It is possible that some contributors to sea level rise have not been documented or well quantified. The rate of sea level rise increased during the 1993-2003 period compared with the longer-term average (1961-2003), although it is unclear whether the faster rate reflects a short-term variation or an increase in the long-term trend. While the global average sea level rise of the 20th century was 4.4-8.8 inches, the sea level has not risen uniformly from region to region. Sea level has been rising 2.0-3.0 mm per year along most of the U.S. Atlantic and Gulf coasts. The rate of sea level rise varies from about 10 mm per year along the Louisiana Coast (due to land sinking), to a drop of a few inches per decade in parts of Alaska (because land is rising). Globally, Indonesia, Thailand, and Bangladesh are experiencing above-average sea level rise. Northwestern Australia is experiencing below-average sea level rise, a trend that is evident in much of the Ocean between western Australia and East Africa. Most of the Pacific and Atlantic basins are experiencing average to above-average sea level rise. Many coastal areas outside of the U.S., Europe and Japan have too few tide gauges to be sure about long-term trends in regional sea level rise. Studies of Roman wells in Caesarea and Roman piscinae in Italy indicate that sea level stayed fairly constant from few hundred years. At TROPMET Symposium held in Hyderabad, Dr. P.K. Das at the end of his award ceremony delivered a lecture in which to my question he answered that out of the 12 sea level observations along the Indian Coasts that at four locations the sea level lowered and at the other 8 stations no change was noticed. The IPCC (2007) expresses high confidence that the rate of observed sea level rise increased from the mid 19th to the mid 20th century. During the 20th century, sea level raised at an average rate 1.2-2.2 mm/year. Tide gauges show little or no acceleration during the 20th century. Satellite measurements estimate that sea level has been rising at a rate of 9 to 15 inches per century (2.43.8 mm/yr) since 1993, more than 50% faster than the rate that tide gauges estimate over the last century. According to the Free Encyclopedia (WIKIPEDIA],


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“the sea level has risen more than 120 m since the peak of the last ice age about 18,000 years ago. However, only – 4 meters of this increase has occurred in the last 6,000 years. From 3,000 years ago to the 19th Century the long-term change was roughly 0.5 m at a rate of 0.1 to 0.2 mm/year. Since 1850, sea level has risen again at 1 to 2 mm/year. Since 1992 satellite altimetry from TOPEX/Poseidon suggests a rate of about 3 mm/year. Based on this they postulated that the increased rates may indicate accelerating sea level change as a result of global warming. During the 21st Century global warming models predict a sea level rise of about 0.5 m”. Since 1992 the TOPEX and JASON Satellite programmes have provided measurements of sea level change. The current data show a mean sea level increase of 2.9 ± 0.4 mm/year. However, because of significant short-term variability in sea level can occur, this recent increase does not necessarily indicate a long-term acceleration in sea level changes. It is unclear whether this represents an increase over the last decades; variability; or problems with Satellite calibration. However, none of these studies looked into changes due to tectonic movements inside the Earth. IPCC predicts in sea level rise using models that by 2100 global warming will lead to a sea level rise of 110 to 800 mm. Rejecting some of IPCC assumptions, Morner (2004) has argued that sea level rise will not exceed 200 mm, within a range of either + 100 to – 100 mm or +50 to ± 150 mm depending upon assumptions. This means, the rise varies between 0 to 200 mm and –100 to 200 mm. Shall we accept such wide range of data as realistic or reject it? In science the acceptable range is ± 10%, at the maximum. Most of these speculative increases in sea level are beyond the observational error ranges. Because of this the ranges present different groups under different measurement modes presents un-realistic high variations that are not statistically or scientifically significant. There are several types of information on sea level rise, which includes model estimates, tide-gauze system observations, satellite altimetry observations, etc. There are several issues involved in resolving the findings because they may be short-term rise or adjustment of long-term ice ages, etc. Thus it became a puzzle and unclear whether the so-called increase over the last decades is variability or problems with tide-gauge/satellite calibration, lacunae in model formulations, etc or due to tectonic movements. Thus sea level rise also traveling in the same boat as global warming! That is, sea level may be rising, lowering and no change at all. 9.4

Extreme Events in Rainfall & Cyclone

9.4.1 Precipitation IPCC (2007) proposes, “Increasing temperatures tend to increase evaporation, which leads to more precipitation. As average global temperatures have risen, average global precipitation has also increased”. IPCC also presented that “Precipitation has generally increased over land north of 30°N from 1900-2005, but has mostly declined over the tropics since the 1970s. Globally there has been no statistically significant overall trend in precipitation over the past century, although trends have widely by region and over time. It has become significantly


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wetter in eastern parts of North and South America, northern Europe, and northern and central Asia, but drier in the Sahel, the Mediterranean, southern Africa and parts of southern Asia. Changes in precipitation and evaporation over the Oceans are suggested by freshening of mid- and high-latitude waters (implying more precipitation), along with increased salinity in low-latitude waters (implying less precipitation and/or more evaporation). The results summarized in Chapter 6 counters some of these observations. There are significant systematic patterns in rainfall data series over different parts of the globe. They also present a system in their variations with latitude, longitude, land-sea, etc. These patterns clearly indicate that the rainfall is currently high over certain parts of the glove and it is lower in certain other parts. However, these are modified in association with the degree of ecological changes in a given region. On the contrary, there is no evidence to prove that the changes in precipitation are associated with global warming. See the Figure 6h standardized time series of rainfall anomalies for the 20th century and a century period of the GFDL model simulation containing the driest episode. The increased evaporation causes increased rainfall is a false theory/logic – it is like wall is white and cow is white and therefore wall is cow. Evaporation is not only relates to temperature factor but also several other meteorological, orographic/topographic, land-sea-elevation factors along with relative humidity (soil & atmosphere), wind, etc (Penman, 1948). Evaporation changes with irrigation/spread of water bodies, as well. Also change with land-use/land-cover changes. That is evaporation changes drastically with “ecological changes” (Reddy, 1983c). Generally, evaporation changes with precipitation but not vice-versa. Also less than 1-degree change in temperature far smaller than the seasonal change observed over different parts as well El-Nino/La-Nino factor that change evaporation. Therefore, there is an urgency to look into the patterns presented in Chapter 6 by adding the latest data of recent decades. This needs as a first step collect all such information from local, regional, national studies world over. They play critical role in agricultural policy decisions at national and global level (Reddy, 1993, 2002, 2006b & 2007]. 9.4.2 Cyclonic storms There is large natural variability in the intensity and frequency of mid latitude storms and associated features such as thunderstorms, hail events and tornadoes. To date, there is no long-term evidence of systematic changes in these types of events over the course of the past 100 years (IPCC, 2007). It also says, “Analyses of severe storms are complicated by factors including the localized nature of the events, inconsistency in data observation methods, and the limited areas in which studies have been performed. The frequency and intensity of tropical storm systems have also varied over the 20th century on annual, decadal and multi-decadal time scales. For example, in the Atlantic basin, the period from about 1995-2005 was extremely active both in terms of the overall number of tropical storm systems including hurricanes as well as in storm intensity. However, the two to three decades


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prior to the mid-1990s were characterized as a relatively inactive period. Following the Atlantic hurricane season of 2005, which set a record with 27 named storms, a great deal of attention has focused on the relationship between hurricanes and climate change”. Numerous studies were published on possible linkages, with a range of conclusions. To provide an updated assessment of the current state of knowledge of the impact of global warming on tropical systems, the World Meteorological Organization’s hurricane researchers published a consensus statement. Their conclusions include (WMO, 2006): “Though there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date, no firm conclusion can be made on this point. There is general agreement that no individual events in [2004 and 2005] can be attributed directly to the recent warming of the global Oceans… it is possible that global warming may have affected the 2004-2005 group of events as a whole. It is only a presumption but not substantiated by facts”. All these highlight “Cat on the Wall” proverb. The newer IPCC Fourth Assessment summary reports says, “There is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with an increase in sea surface temperature, but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations”. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones. Unfortunately no scientist questions such inferences as year to year variations in temperature are far higher [ten to twenty times] than the global temperature raise by that time (less than 0.4 0C). Reports say, “Accumulating evidence suggests that hurricanes are becoming more intense due to global warming”. Research by Michael Mann from Penn State and Kerry Emanuel from MIT suggests that warming of the tropical Atlantic due to human activity is responsible for the recent increase in tropical cyclone activity. They also concluded that there is no statistically significant evidence for natural cycles, such as the Atlantic Multi-decadal Oscillation (AMO), playing a role in long-term tropical North Atlantic sea-surface-temperature variations, which are well correlated with tropical cyclone intensity. Mann and Emanuel found that the dependency of tropical Atlantic sea surface temperature on the AMO is not statistically robust, and that any trend recently accredited to the AMO may actually be a result of global warming in conjunction with cooling associated with tropospheric aerosol pollutants, such as sulfur dioxide and nitrogen oxide. Two researchers from Purdue University also independently concluded that mean annual tropical temperatures directly regulate the total power unleashed by tropical cyclones. By using observational data from the European Centre for MediumRange Weather Forecasts Reanalysis Project, Sriver and Huber found that the power dissipation of tropical cyclones (a measure of maximum wind speeds over the duration of the storm) correlates with both air temperature and mean annual


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tropical sea surface temperature, and that a substantial portion of variance in globally integrated power dissipation can be attributed to changes in mean tropical temperatures. Analysis of the record-breaking 2005 hurricane season also reveals that higher than usual global sea surface temperatures, a signature of global warming, were responsible for the majority of the record high sea surface temperatures documented in the tropical North Atlantic during the summer of 2005. Trenberth and Shea attributed approximately half of the record warmth in the tropical North Atlantic to global sea surface temperatures, whereas only a third of the warmth was caused by the AMO and El Niño combined. As the background levels of global sea surface temperatures continue to climb, we can expect greater hurricane activity in future. On the contrary, the history of cyclones/typhoons/hurricanes presents a system in their occurrence patterns of severity and frequency (Reddy, 2007). In USA according to NASA data, Hurricanes were severe in intensity during 1940s, 1950s and 1960s; they were less severe in intensity during 1970s, 1980s and 1990s. Now again they are severe in intensity similar to the period in 1940s-60s (Figure 9b). This pattern is similar to the pattern observed in the All-India Southwest Monsoon Rainfall (Reddy, 2003a, 2006b). The all-India Southwest Monsoon 60year cyclic pattern (Figure 6s) is presented by a sine curve along the horizontal axis in Figure 9b. Rajeevan, et al. (1999) observed, in 1959 to 1991 data, significant Inverse relationship between Northwest Pacific activity as measured by typhoon days during Summer months (June to September) and Indian Summer Monsoon Rainfall (Table 12). That means the cyclonic activity in the Northwest Pacific are in opposition to the Hurricane activity. Similar but opposite pattern of Hurricanes is evident in the case of frequency of the cyclonic storms and depressions during Northeast Monsoon season (October to December) in India during 1951-81(Indira, 1999) – the frequency is less than 6 in the 1940s-60s and more than 6 in the 1970s-90s. Table 12: Number of years under different groups of Typhoon days vs all-India Summer Monsoon Rainfall during 1959-1991 [26-years] Typhoon Days Groups

Number of years All-India Summer Monsoon Rainfall groups Drought

Normal

Flood

Deficit

1

3

4

Normal

2

7

1

Excess

6

2

0

Note: Normal = 8 typhoon days; deficit/excess = <8/>8 typhoon days; Drought/Flood = < 10%/> 10% of normal rainfall The frequency of occurrence of cyclones per year in Bay of Bengal during 1945 to 2000 (May to November) as presented by joint Typhoon Warning Centre shows a


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drastic reduction around 1975s (Reddy, 2006b) — (Figure 9c). This followed the Southwest Monsoon rainfall pattern in Andhra Pradesh. The Southwest Monsoon rainfall 56-year cyclic pattern (Figure 6t) is presented by a sine curve along the horizontal axis in Figure 9c. Srivastava, et al. (2004) also presented this trend in the annual frequency of cyclonic storms over the Arabian Sea and Bay of Bengal for the period 1961-2002. Bay of Bengal storm activities presented a decreasing trend – in association with this the Orissa rainfall presented a decreasing trend. This period coincides with below the average rainfall cycle of Southwest Monsoon season of Andhra Pradesh [1973 to 2001]. Andhra Pradesh rainfall is more associated with the frequency of occurrence of the depressions/storms in the Bay of Bengal. Jadhav (2004) computed the total number of low-pressure systems and Depressions/storms for the monsoon months June to September for the period 1891-2000 – Rajendra Kumar (2004) data also followed this pattern.


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However, the low-pressure systems are not confined to Andhra Pradesh alone but are spread all over India while the majority of depressions/storms influences the Andhra Pradesh rainfall. Though low-pressure systems do not present a systematic variation, the depressions/storms followed the Southwest Monsoon rainfall pattern of Andhra, wherein during the 1973 to 2001 presented lower number compared to the previous 28-year period. Previous to this 28-year period again presented lower number of depressions/storms. Though during 1973 to 2001 depressions/storms present a steep fall (Srivastava et al., 2004), the total number of low pressure systems present no such fall. The steep fall in storms/depressions present fall in rainfall along the East Coast but because of low-pressure systems the rainfall over other parts haven’t sown such fall. These clearly point out one thing that there is significant relationship among cyclonic activity over different oceans-seas and rainfall patterns. There is a need to look into this aspect by taking into account the solar-planetary system. 9.4.3 Un-usual events in Precipitation & Temperature Precipitation: IPCC (2007) presented that “There has been an increase in the number of heavy precipitation events over many areas during the past century, as well as an increase since the 1970s in the prevalence of droughts—especially in the tropics and subtropics. Observations compiled by NOAA’s National Climatic Data Center show that over the contiguous U.S., total annual precipitation increased at an average rate of 6.1 percent per century since 1900, although there was considerable regional variability. The greatest increases came in the East North Central climate region (11.6 percent per century) and the South (11.1 percent). Hawaii was the only region to show a decrease (-9.25 percent). In the Northern Hemisphere’s mid- and high latitudes, the precipitation trends are consistent with climate model simulations that predict an increase in precipitation due to humaninduced warming. By contrast, the degree to which human influences have been responsible for any variations in tropical precipitation patterns is not well understood or agreed upon, as climate models often differ in their regional projections”. Sharma & Sharma (2007) presented that “Barmer in Rajasthan, recorded 302 mm on September 1968 almost double the 160 mm rainfall of 22 August 2006. There was heavy rainfall in Jodhpur in 1979 and 1981”. Andhra Pradesh (AP) comprises three meteorological sub-divisions, namely Coastal Andhra, Rayalaseema and Telangana. Andhra Pradesh presents a typically unique pattern, varying from wet to dry climates. The State receives rainfall from both the Southwest and the Northeast Monsoons. With the cyclonic activity in both the monsoon seasons, the rainfall over different parts of the State present highly variable patterns both in time & space. In fact predominantly the rainfall is mainly associated with cyclonic disturbances. With all these the climate presents dry or arid Anantapur to Wet Adilabad. As it is seen from Table 11 (Reddy, 2000a) that Andhra Pradesh receives rainfall in two monsoon seasons, namely Southwest Monsoon (June to September] and Northeast Monsoon [October to December].


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Table 11: Average rainfall amounts & C.V.s in the three meteorological sub-divisions of AP during 1871-1990 Region

Parameter

SWM

NEM

Annual

India

Mean, mm C.V., %

852(78) 9.9

120(11) 29.0

1090 19.5

CA

Mean, mm C.V., %

507(52) 22.2

375(39) 38.8

971 19.8

T

Mean, mm C.V., %

722(80) 23.5

107(12) 60.3

899 21.7

R

Mean, mm C.V., %

422(60) 28.8

204(29) 41.9

709 21.6

Note: CA = Coastal Andhra, T = Telangana, R = Rayalaseema, SWM = Southwest Monsoon, NEM = Northeast Monsoon, C.V. coefficient of variation, number within the brockets refer to % of SWM & NEM to Annual rainfall The contribution of rainfall during these two monsoon seasons in three sub-divisions is quite different. During SWM Telangana region received 80% of the annual rainfall. These are reduced to 60% in Rayalaseema region and 52% in Coastal Andhra region. They are respectively 12, 29 & 39% during the NEM. The spatial variation of drought risk presents 5 to 60% of the years, with the highest risk in Anantapur region (Reddy, 1993). The year-to-year variations in rainfall & onset dates of Southwest Monsoon are very high (Reddy, 2000a), which can be seen from the rainfall extremes (Table 12). Table 12: Extreme events of rainfall & onset dates in AP during 1871-1994 Period

L (mm/year)

H (mm/year)

Coastal Andhra Annual SWM NEM

532/1891 309/1888 88/1909

489/1920 371/1877 2/1988

226/1876 192/1904 12/1876

28/5/1925

24/6/1959

28/5/1925

24/6/1959

24/5/1933

24/6/1959

1485/1893 1186/1988 310/1987

Rayalaseema Annual SWM NEM

D

1501/1990 780/1978 703/1994

Telangana Annual SWM NEM

E

1228/1874 791/1878 455/1946

Note: SWM = Southwest Monsoon, NEM = Northeast Monsoon, L = the Lowest rainfall, H = the highest rainfall; and E = the earliest date & D = delayed date of onset of monsoon rains


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It is seen from Table 12, the highest and the lowest rainfall amounts received during 1871 to 1994 [124 years] in the three meteorological sub-divisions of Andhra Pradesh that in Telangana Sub-division the highest annual rainfall was received during 1893 and the lowest annual rainfall was received during 1920; in the case of Coastal Andhra they are during 1990 & 1891; and in the case of Rayalaseema they are during 1874 & 1876. The figures for Southwest Monsoon and Northeast Monsoon are quite different when compared to annual rainfall. In the last onedecade the lowest values have not crossed the mark presented in Table 11 & 12 but the highest values crossed the mark as there is an increasing trend in rainfall due to large changes in land-use pattern. Munot (2004) presented an analysis of all-India Summer Monsoon rainfall in terms of deficit and excess rainfall years during 1871-2001. The highest rainfall of 1020.3 mm, which is 19.9% above the mean rainfall of 850.8 mm, was received in 1961; after this, 18.0% was received in 1917; 16.6% in 1892; 15.6% in 1956; etc. The lowest rainfall of 604.3 mm, which is 29.0% below the mean rainfall of 850.8 mm, was received in 1877; after this, 26.1% was received in 1899; 23.5% in 1918; 23.3% in 1972, etc. Let us see the four years data of rainfall received in three Andhra Pradesh sub-divisions (Reddy, 2003b) as % of average rainfall in Southwest Monsoon and Northeast Monsoon (Table 13). In the case of Coastal Andhra the rainfall during Southwest Monsoon varied between 59% and 143% and in the case of Northeast Monsoon varied between 35% and 177%. The same in Telangana are 81% and 146%; 46% and 290% while they are 87% and 146%; 31% and 159% in Rayalaseema. Quite large differences though followed the same pattern. Table 13: % average rainfall in the three sub- Divisions of AP during 1987-1990 Year

Rainfall in % of average SW CA

NE T

R

CA

T

R

81

90

177

290

159

1987

59

1988

143

146

146

45

48

31

1989

142

139

145

35

46

47

1990

90

113

87

130

193

132

Note: SW = Southwest Monsoon; NE= Northeast Monsoon; CA = Coastal Andhra; T = Telangana; and R = Rayalaseema In the State of Andhra Pradesh in India during summer, heat waves are common reaching as high as 50 oC. During 2008 May the heat wave prevailed for several days along the South Coastal belt & Telangana, reaching as high as 45 oC and above. Some of these conditions are associated with cyclonic disturbances in the southern Bay of Bengal. During winter, when the Western Disturbances in northwest India were pushed southward, Andhra Pradesh also experiences severe cold weather or cold waves conditions. In Andhra Pradesh, the State Government


179


initiated cloud seeding programme in drier areas. Though the organizers of the programme claimed in their reports submitted to the government that rainfall has increased but in reality the rainfall has presented strong decrease in downwind direction. I brought this to the notice of government with examples taken from the seeding experiments. The technical committee advised the organizers not to seed intensive synoptic systems even otherwise they give copious rainfall in areas in the windward direction. But, the company executing the operation, invariably seed such systems only, saying that “it is not binding on us as it is not the part of our contract”. Therefore, if this programme continues there is a high possibility of rainfall pattern may present drastic changes. This may have severe negative impact on agriculture & water resources in the state in coming years. In Andhra Pradesh both government sponsored and private and communists sponsored destruction of forests are going on in several thousands of acres that may also severely increase the temperatures and decrease the rainfall – researchers showed there is considerable increase in rainfall & decrease in temperature in areas where considerable area was brought under reforestation. Though, these are countered somewhat by some of the irrigation projects and associated “increased area” under water reservoirs & greenery, land use change from dry-land to wetland. Mohan Lal Sahu (2004) data for Chattisgarh presents a mean summer monsoon rainfall of 1232.2 mm. The highest rainfall of excess 47.8% of average was recorded in 1961; following this in 1925 received 31.3%, 30.0% was received in 1936, 27.4% in 1980, 24.0% in 1994. The lowest rainfall of deficit 29.1% was received in 1987; following this 28.9% was received in 1941, 26.76% in 1974, 24.46% in 1966, 22.08% in 2000. The Cochin highest rainfall data along with their year of occurrence in different months at daily & monthly interval presented by Bindu & Rajan (2004) for the period 1901 to 2000 do not give the impression that the unusual falls are associated with a particular period (Table 14). Table 14: Monthly and daily highest rainfall of Cochin Month

1

2

3

4

5

6

January February

21.1 17.0

1921 1984

13.3 9.0

1921 1952

10 11

2.4 2.8

March

24.5

1960

12.6

1960

7

4.8

April

34.3

1908

16.2

1956

11

11.9

May

107.6

1933

25.3

1933

24

31.8

June

121.6

1912

34.7

1959

29

72.4

July

145.4

1968

21.4

1910

31

63.3

Augus

119.9

1931

15.6

1947

31

37.8

September

68.4

1988

11.6

1959

29

26.5

October

90.6

1932

23.2

1951

30

31.0

November

47.6

1966

15.4

1966

12

16.9

December

28.0

1972

15.5

1946

6

5.1


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Note: 1 = average highest rainfall of the month, mm; 2 = year of the highest; 3 = average highest rainfall of the day, mm; 4 = year of the highest; 5 = average rainy days of the month; 6 = average rainfall of the month, cm Thapliyal, et al. (2004) observed that the magnitude and persistence of changes are not large enough to conclude that the increase of extreme reflects a non-stationary climate. As the skew-ness increases in the rainfall data the limits of variation (% variations) also present higher values. These can’t be attributed to unusual events. The skew-ness in the data series increases from a region to a location, from annual to seasonal to monthly to weekly to daily to hourly data. However, rainfall presents an increasing/decreasing trend over different parts of the country based on the changes in local environment in addition to systematic variations. Temperature: The author developed concepts to estimate radiation over different parts of the globe since 1971 (see Chapter 3). In this venture he found rainfall is more associated with radiation (Reddy, 1987). In line with this, the global temperature pattern presents a similarity with the Andhra Pradesh Southwest Monsoon Rainfall cycle. Figure 9d presents the global annual & five-year average temperature series. On the horizontal axis presented the 56-year cycle (sine curve) observed in the Southwest Monsoon Rainfall of Andhra Pradesh. The period with steep raise during around 1910 to around 1945 present below the average rainfall cycle, then the period around 1945 to around 1975 period of little variation present the above average rainfall cycle, and the period with steep rise around 1975 to around 2005 present below the average rainfall cycle. During the third cycle (1973 to 2028) in the dry 28-year cycle the temperatures gone up – during this part Gangotri Glacier presented higher retreat. A report appeared in media says that the coming 10-years temperatures will not go up!!! This aspect must be thoroughly studied at global level, as after increasing the temperature during the below average rainfall cycle the temperature is not coming back during the above average rainfall cycle, though it is not showing an increasing or decreasing trend. Why? This needs an answer. During 1971 to 2000, West Rajasthan experienced the longest heat wave spell of duration 16 days and most of the longest spells were experienced in 1972 and during this period the number of sub-divisions affected by cold wave and heat wave spells presented an increasing trend (Pai & Rajeevan, 2004) but both of these are confined mainly to their traditional zones only (Reddy & Rao, 1978). Alwar, on the fringes of the Thar Desert, registered a temperature of 50.6 °C (123 °F), India’s highest. India’s lowest recorded temperature reading was -45 °C (-49 °F) in Dras, Ladakh, in eastern Jammu and Kashmir; however, the reading was taken with non-standard equipment. Further south, readings as low as 30.6 °C (-23 °F) has been taken in Leh, also in Ladakh. However, temperatures on the Indian-controlled Siachen Glacier near Bilafond La (5,450 meters (17,881 ft)) and Sia La (5,589 meters (18,337 ft)) have fallen below -55 °C (-67 °F), while blizzards bring wind speeds in excess of 250 km/h (155 mph), or hurricane-force


181



182


winds ranking at 12 (the maximum) on the Beaufort scale. It was those conditions, not actual military engagements that were responsible for more than 97% of the roughly 15,000 casualties suffered by India and Pakistan over the course of conflict in the region. The highest reliable temperature reading was 50.6 °C (123 °F) in Alwar, Rajasthan in 1955. This mark was also reached at Pachpadra in Rajasthan. Recently, claims have been made of temperatures touching 55 °C (131 °F) in Orissa; the IMD, which has questioned the methods used in recording such data, has met these with some skepticism. From these presentations it is clear that unusual events in weather & climate are not associated with a specified period to attribute them to global warming phenomenon but they are seen at random – like “anything may happen at any time” similar to earthquakes, forest fires, etc. There is a close relation in observed fluctuations in different weather parameters such as temperature, cyclones/ hurricanes, precipitation.


183


Summary Weather is what we experience daily and climate is the average of such weather over a long period of time. The climate is highly variable with space and time. The climate defines the life forms on the Earth. Natural variations: Climate consists of irregular variations and systematic variations. The systematic variations are known as cycles. They are of long-term and shortterm fluctuations. The long-term fluctuations are termed as ice ages, mainly present in temperature. These are derived through proxy data, which vary with author to author. The short term fluctuations are studied using ground based observed meteorological data. This aspect is studied primarily with reference to precipitation data series, as it is the prime factor in the success and failure of agriculture. Where such fluctuations are present, climatic-normal play a misleading role. Precipitation data analyzed taking into account the climatic fluctuations, the results provide better planning tool for successful agriculture (see Reddy, 1993). However, to make the results more reliable, the observed meteorological data series must be homogenized at base level through studies to separate the

-

-

Errors due to change in unit of measurements;

-

Errors due to changes in place of measurement;

-

Errors due to changes in war related disturbances;

-

Errors associated with the changes in and around meteorological observatory; Now, in majority of developing countries the meteorological stations are in dilapidated condition due to wars & poverty; etc.

Man-induced changes: With the unabated population growth under changed life style & technology, weather & climate are affected severely by the changes in atmospheric composition, land-use & land-cover changes. These changes are known as trend – both increasing and decreasing. The observed surface temperature presents an increasing trend with several ups & downs during the last 100-years. Some claim it is the result of increased concentrations of anthropogenic greenhouse gases in the atmosphere. The temperature pattern derived through models using anthropogenic greenhouse gases as input present smooth non-linear increase and that vary with model to model. It is clear from these that the increased temperature is not a result of anthropogenic greenhouse gases concentration in the atmosphere but it is the result of combination of several factors. The anthropogenic greenhouse gases observed data is available from the last five decades only and that too at few unevenly distributed network of stations over the globe. Prior to this period the data series are constructed through proxy data. Unlike in observed surface temperature, the carbon dioxide data presents a smooth non-linear increase.


184


Urban contamination: The observed surface temperature series are contaminated by “urban-heat-island effect” – a warming effect. The observed surface temperature data series represent measurements made mostly in urban-areas, as majority of the meteorological observatories are located in urban centers. The observed temperature must also be homogenized at base level like in precipitation. However, the rural temperatures on the contrary are contaminated by “rural-cold-island effect” – a cooling effect — with the changed land-use & land-cover. Land & Sea effect: The land area covers one-third of the globe and oceans by two-thirds. The observed meteorological data over the oceans is insignificant when compared to on land meteorological observations network. For the last two decades, with the help of satellites the temperature data was derived over the land & oceans. The temperature pattern derived from satellites is far lower than the observed surface temperature data. Unfortunately, later, the satellite data series were revised to fit with the observed surface temperature pattern. This created doubt in the use of satellite data series after seeing the observed surface temperature data series in Southern Hemisphere with less land area & more ocean area presenting lower temperatures when compared with the Northern Hemisphere!!! Ozone depletion: The fact is that both the ozone “creation & destruction” and “cooling & warming” of temperature are in built in nature. There is an absolute one-to-one relation in ozone depletion theory and thus, though in the initial stages there was a stiff opposition from industry, it became easy to replace ozone depleting substances by non-ozone depleting substances. The reverse trend in ozone depletion is already evident. The stratospheric cooling effect is more in association with weather related formation of circum-polar vortex, which is more frequent in the South Pole zone & less frequent in the North Pole zone. This is reflected in the ozone depletion patterns at the two poles zones. Unfortunately, there is no such one-to-one relation in global warming theory, as there are several process involved. The issue is not moving in the right direction, as political interests are inter-woven in the issue of global warming, which is leading no where. Glaciers retreat & sea level raises: In the glaciers retreat phenomena, some powerful groups started suppressing the facts. They are not looking glaciers retreat as a long-term cyclic pattern & part of hydrological cycle as well physical impacts associated with several phenomena in nature & human injected. Some scientists noted decreasing temperature in parts of South Pole zone and Himalayan Glaciers zones. The observed sea level changes present decreasing trend in certain parts of the globe; increasing trend certain other parts with majority of the parts presenting no change. However, the speculators of sea-level rise, using the model based simulations, flooding the literature with speculations of abnormal rise in sea levels with wide ranges that are far beyond model error ranges.


185


We are well aware that physical impact as a result of research, sports, tourism, pilgrimage activities (that is, human activity), impact of outer space objects falling, in addition to earthquakes, volcanoes, land-slides, tectonic movements under the Earth, etc needs careful study in terms of rise in temperatures and or melting of ice-sheets – sea level rise. This aspect is researched very little!!! The fact is that during glacial & interglacial periods the increase & decrease in temperature was responsible for increase & decrease in carbon dioxide concentrations in the atmosphere. That is, it is an after affect. The present global warming theory presents the vice-versa process. Systematic variations & Unusual events: Unusual events in weather & climate are not associated with a specified period to attribute them to global warming phenomenon but they are seen at random – like “anything may happen at any time” similar to earthquakes, forest fires, etc. The precipitation data from both Southern & Northern Hemispheres present systematic variations. The observed cycles varied between 66 to 22 years along with their sub-multiples. The ups-and-downs observed in global average observed surface temperature data series present a positive relation with the fluctuations in precipitation. Similar type of relationship was noted in cyclonic/hurricane activity with the fluctuations in precipitation. However, the pattern is not uniform all over the globe but present variable patterns according to zones/regions. That is, averages have no meaning but must be studied region-wise to get correct picture. The precipitation & weather present a relationship with the changes in solar & planetary system. The influence of these changes, change with the prevailing local synoptic conditions. In some cases, the patterns present reversals. These must be studied in relation to the prevailing fluctuations at a given region/zone to get better picture. We must not forget that the sea/ocean tides follow a rhythmic pattern with phases of the Moon. In conclusion, as long as our governments sub-serve the interests of Western Multinational Companies and their propaganda agents, we achieve little in this direction. They put foot in the energy projects & major irrigation projects to obstruct to get the fruits of development by rural poor but they are going ahead un-hindered with the chemical inputs in agriculture under heavy subsidies as usual to benefit MNCs. This is the root cause of all ills in the society in developing countries. In this bandwagon entered the genetically modified technology of MNCs that have severe repercussions on ecology & agriculture of developing countries like India. Even IPCC is putting its’ stamp of approval on such tendency!!! Majority of the conclusions in relation to global warming hypothesis are either follow the proverb “Cat on the Wall” or put forth false logic “wall is white and cow is white, therefore wall is cow”. Therefore, we must come out from this phobia to understand the climate change in its’ totality by giving weight to “science” over the “number” game.


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Reddy, S.J. & Mersha, E., (1990). Results: climatic fluctuations in the precipitation data of Ethiopia during the period of meteorological record. Agrocl. Series 4, ETH/86/021-WMO/UNDP, NMSA, Addis Ababa, Ethiopia, 28p.


191


77.

Reddy, S.J., (1993). Agroclimatic /Agrometeorolocal Techniques: As applicable to Dry-land Agriculture in Developing Countries. JCT, Hyderabad, 205p — Book Review appeared in Agric. For. Meteorol., [original name Agric. Meteorol.] 67:325-327 [1994].

78.

Reddy, S.J., (1995). Discussion: Over-emphasis on energy in crop yield models. Agric. For. Meteorol., 77: 113-120.

79.

Reddy, S.J., (2000a). Andhra Pradesh Agriculture: Scenario of the last four decades, Jeevan Charitable Trust, Secunderabad, A.P., India, 104p.

80.

Reddy, S.J., (2000b). The concept of prophysing: Myths & Realities. Jeevan Charitable Trust, ICRISAT Colony, Secunderabad, A. P., India, 100p.

81.

Reddy, S.J., (2002). Dry-land agriculture of India: An agroclimatological and agrometeorological perspective, BS Publications, Hyderabad, India, 429p.

82.

Reddy, S.J., (2003a). The impact of climate change on water resources availability. Edited by B. Venkateswara Rao, et. al., Proc. Of International Conference on Hydrology and Watershed Management: With a focal theme on water quality and conservation for sustainable development, BS Publications, Hyderabad, A.P., India, pp. 227-238.

83.

Reddy, S.J. (2003b). Rainfall deficit and drought intensity. Drought Management: Present & Future (with special reference to Andhra Pradesh), Sundaraiah Vignana Kendram, Hyderabad, pp.29-44 & 164-167.

84.

Reddy, S.J., (2004). Cloud Seeding: Myths & Realities. Proc. of AP Akademi of Sciences, 8: 109-117.

85.

Reddy, S.J., (2005). Rainfall prediction for agriculture: Past, Present, and Future.Edited by Y. L. Nene, Agricultural Heritage of Asia: Proceedings of the International Conference, Asia Agri-History Foundation, Secunderabad, A.P., India, pp. 147-154.

86.

Reddy, S.J., (2006a). Is Biotechnology a Gateway to Environmental Destruction? National seminar of Recent Advances in Biotechnology and Bioinformatics, School of Biotechnology of MGNIRSA, Domalguda, Hyderabad, A.P., India, pp.133-147.

87.

Reddy, S.J., (2006b). Effect of climate change on water & environment. Proc. of International Conference on Hydrology and Watershed Management with a focal theme on Improving water productivity in the agriculture, 5-8 December 2006, JNTU, Hyderabad, India.

88.

Reddy, S.J., (2006c). Environment and People. Jeevan Charitable Trust, Hyderabad, A. P., India, 360p.

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About the Author JCT, Hyderabad Plot No. 277, Road No. 78, Jubilee Hills Phase-III, near Padmalaya Studio Hyderabad – 500 033, A.P., India Tel. (040) 23550480/23540762 E-mail: [email protected]

Dr. Sazzala Jeevananda Reddy had his M.Sc. (Tech.) in Geophysics and Post-Graduate Diploma in Applied Statistics from the Andhra University – Vishakapatnam, Advanced Training in Meteorology & Oceanography from the Training School of India Meteorological Department – Pune, Ph.D. in Agricultural Meteorology from the “The Australian National University”, Canberra. Published around 500 scientific articles. Dr. Reddy was formerly Chief Technical Advisor — WMO/UN and Expert – FAO/UN. Presently serving the cause of Environment. The following are the other books of the author. •

An agroclimatic classification of the semi-arid tropics: An agroclimatic approach for the transfer of dry-land agricultural technology. Ph.D. Thesis, The Australian National University, Canberra, Australia, (1985), 260p.

•

Agroclimate of Mozambique: As relevant to dry-land agriculture. Comunicacao No. 47, Serie Terra e Agua, INIA, Maputo, Mozambique, (1986), 70p.

•

Agroclimatic/Agrometeorological Techniques: As applicable to dry-land agriculture in developing countries. JCT, Hyderabad, A.P., India, (1993), 205p – Book Review appeared in Agric. For. Meteorol., 67:325-327 [1994].

•

Vastu: A Practical Guide (in English) & Vastuvyamoham: Bramalu-Vastavalu (in Telugu). JCT, Hyderabad, A.P., India, (1997), 106/140p – Book Review appeared in The Hindu and several other dailies.

•

Andhra Pradesh Agriculture: Scenario of the last four decades. JCT, Hyderabad, A.P., India, (2000), 104p.

•

The concept of prophesying: Myths & Realities. JCT, Hyderabad, A. P., India, (2000), 100p.

•

Dry-land agriculture of India: An agroclimatological and agrometeorological perspective. BS Publications, Hyderabad, A.P., India, (2002), 429p.

•

Advanced Technologies in Meteorology. Edited by R. K. Gupta & S. Jeevananda Reddy, Tata McGraw-Hill Publ. Comp. Ltd., New Delhi, India, (1999), 549p.

•

Environment and People. JCT, Hyderabad, A. P., India, (2006), 360p.

•

Agriculture & Environment. JCT, Hyderabad, A.P., India, (2007), 112p.

Price: Rs. 200/-

Climate Change Myths and Realities

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