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October 16th, 2001 Deep Impact
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According to the International Institute for Applied Systems Analysis (IIASA), Austria, India stands to lose 125 million tonnes (or 18 per cent) of its rain fed cereal production potential. If agricultural production goes down, the price of staple food commodities will increase (see table: Plummeting production). |
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According to a study by the World Bank, a 2ºC rise in temperature along with a seven per cent increase in rainfall will reduce net agricultural revenues by 12.3 per cent for the whole country. |
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Agriculture in the coastal regions of Gujarat, Maharashtra and Karnataka will be the most negatively affected. |
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An increase in winter temperature by 0.5ºC will result in a 10 per cent reduction in wheat yield in the high yield states like Punjab, Haryana and Uttar Pradesh. |
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An increase in minimum temperature from 18ºC to 19ºC will result in a decrease in rice yield of 0.71 tonne per ha, while an increase from 22ºC to 23ºC will result in a decrease of 0.41 tonne per ha. |
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Even if there is some farm level adaptation, such as the enhanced use of fertilisers and use of different seeds, the loss in farm level net revenue will range from 9-25 per cent for a rise of 2-3.5ºC. |
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According to Lal, there will be some positive effects of climate change due to increase in carbon dioxide in the atmosphere resulting in what is known as "carbon dioxide fertilisation". For example, Madhya Pradesh produces 72 per cent of soybean grown in India with 77 per cent of its area devoted to soybean farming. According to some simulations, a 50 per cent increase in soybean yield could be obtained if atmospheric carbon dioxide concentration doubles. But temperature increase limits this gain; a rise of 1ºC in minimum temperature with doubled carbon dioxide concentration limits the yield increase to 48 per cent. It was found that the positive effects of elevated carbon dioxide almost cancel out with enhanced thermal stress. Deficient monsoon rainfall conditions combined with thermal stress will adversely affect the positive effect of elevated carbon dioxide on the soybean crop in Madhya Pradesh. |
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Moreover, studies using models that project an increase in crop yields due to carbon dioxide fertilisation are done with the assumption that carbon is a limiting factor in crop growth. This is not the case in India as other nutrients and water may impose more serious restraints. |
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The maximum yield for both rice and wheat are obtained at surface temperatures of 1ºC below the present day climate at current carbon dioxide levels. The yields decline more sharply for a rise in temperature. A 3ºC rise in air temperature almost cancels out the positive effect of elevated carbon dioxide on wheat and rice yields. |
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Climate change will cause a significant increase in pest populations, since generally warmer and moist conditions with longer freeze free periods are highly conducive to them. |
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Reduction in soil moisture due to higher rates of evaporation will be an important stress factor for plants. |
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Changes in forests will alter the configuration and productivity of forests ecosystems. These changes will affect traditional livelihoods, industry, biodiversity, soil and water resources and therefore, agricultural productivity. |
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Under some climate change models, soil moisture is likely to decline and in turn, reduce forest productivity. For example, teak productivity will decline from 5.40 cubic metre per ha to 5.07 cubic metre per ha. The productivity of moist deciduous forests could decline from 1.8 cubic metre per ha to 1.5 cubic metre per ha. |
Health holocaust
More and more people
will fall victim to serious illnesses and a host of deadly diseases
THE health impacts of climate change are difficult to
calculate since most human health problems have multiple factors. Demographics,
environmental degradation and socioeconomic conditions are major factors in illness and
disease.
Climate related shortages in natural resources like fresh water will exacerbate health problems. | |
According to the World Heatlh Organisation (WHO), there will be a drop in deaths and illnesses related to cold, but those caused by heat will intensify. The number of people dying during heat waves will increase. In urban areas, this will be exacerbated by air pollution. |
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Climate change will add to the numbers suffering from infectious diseases. Temperature and rainfall affect the distribution of disease vectors and disease-organisms, as well as the vulnerability of populations to these diseases. An example of this can be seen in the case of mosquitoes. Various species of mosquitoes carry malaria, dengue fever, yellow fever, and several types of encephalitis. Cold is usually the limiting factor in mosquito survival, so any increase in minimum winter temperatures is likely to extend mosquito ranges into cooler climes or higher altitudes. |
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According to the World Resources Institute (WRI), Washington DC, higher temperatures also speed up the life cycles of both the mosquito and the disease organisms they harbour and make adult mosquitoes bite more often. At 30°C, the dengue virus takes 12 days to incubate in the Aedes aegypti mosquito, but only seven days at 32°C. The shorter incubation period translates to a potential threefold higher transmission rate of the disease. Higher temperatures also produce smaller adult mosquitoes that must feed more often to develop an egg batch, which, in turn, increases the chances of disease transmission. Some models suggest that the rise in incidences of malaria globally will be as high as 10 to 20 per cent. |
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Prey-predator relationships like that of frogs and mosquitoes, which control disease-bearing organisms, may break down leading to an increase in vector numbers. |
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Water-borne diseases including cholera and diarrhoeal diseases caused by organisms such as giardia and salmonella could also be affected as rainfall patterns change, along with human access to water supplies and sanitation. |
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According to WHO, global warming will increase the incidence of respiratory and cardiovascular diseases in arid and semi-arid parts of India. |
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Global warming and increased ultraviolet (UV) radiation will both accelerate the photochemical reaction rates among chemical pollutants and increase ozone concentration in urban areas. Ozone and other photochemical oxidants are associated with many respiratory diseases and cancer |
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Incidences of cataracts and skin cancer will increase due to an increase in UV radiation. | |
It is estimated that the average number of tropical disturbance days (with storms or cyclones) may jump twofold causing illnesses, disease, injuries and loss of lives. In the North Indian Ocean, the average number of tropical disturbance days will increase from 17 to 29 days per year under conditions of doubled carbon dioxide concentration. Cyclone storms approach the 7,000 km long Indian coast from both the Bay of Bengal and the Arabian Sea. |
Biodiversity blues
Unable to adapt to rapid
changes, many species will die out
THERE is concern that genes, species, and ecosystems are being
lost due to deforestation. Climate change will aggravate this attrition problem by
disrupting delicate relationships within ecosystems. Loss of biodiversity seems to be
implicit in most global warming scenarios. Many species considered at risk now will become
extinct.
According to IPCC, the range and abundance of plants and animals could change dramatically under changing climatic conditions, and some species are likely to be unable to adapt or migrate to new locations. Most plants and animals can tolerate only a narrow range of ambient temperature. If the temperature varies significantly from this range, normal physiological functioning breaks down. |
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Even more evolved forms of plants and animals that seem to be able to exist in wider climatic ranges need long periods of time to adapt to variations. If change is rapid, they will not be able to adapt, and will die out. |
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Slow-moving species could lose out to weeds and pests that can move or adapt quickly. Plant and animal pests will be affected in the same way as human disease vectors. |
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Rural and tribal communities all over India are dependent on biological resources for food, fuel, shelter and medicine. If there are shifts or movements in ecosystem affecting the biodiversity of a region, the people living in those areas will be deeply affected. |
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Forests will migrate to higher altitudes and transform from drier to more moist types. | |
Mountain ecosystems are projected to shift to higher elevations, although the rate of vegetation change is expected to be slow and the success with which they colonise new habitats will be constrained by local geographical features. For species that are already at their maximum altitude, this is not an option and extinction seems a distinct possibility. |
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Biodiversity hotspots like the Western Ghats are an important resource base because of their high degree of endemism, biodiversity and productivity. Global warming could put their stability at risk since they cannot move to higher altitudes. |
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Ecosystems that cannot move northwards at a rate dictated by global warming will be most at risk. These include glacial ecosystems, coral reefs and atolls, forests, Himalayan systems. |
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Unlike many terrestrial ecosystems, coral reef ecosystems appear to be directly threatened by globally increasing atmospheric carbon dioxide. The calcification rates of corals, coralline algae, and coral-algal communities depend on calcium carbonate available in surrounding seawater, and is expected to be reduced by rising atmospheric carbon dioxide. This represents a serious climate-related threat to the functioning of reef ecosystems that will add to the already existing anthropogenic local stresses in places like the Andaman and Nicobar islands. |
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Though coral reefs in these areas will most likely be able to keep up with the rise in sea level, they probably will not survive a rise in sea temperature. |
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Global warming is already contributing to the decline of mangrove forests. Mangroves protect the shoreline, provide wood and fuel. They are also breeding sites for birds, and act as nurseries for fish. At places where urban development and industries are destroying mangroves, the problems caused by sea level rise and thermal stress will be particularly acute there. |
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Salt-water intrusion from sea level rise will damage fresh water ecosystems. Loss of coastal wetlands will result in resident and migrating species having to shift their habitats. |
Water woes
Extreme events will adversely affect
water resources
WATER availability and recharge are expected to be highly vulnerable to
climate change. Fluctuation in rainfall will lead to instability in the country's water
supply. Besides, climate change may also worsen water pollution.
According to M Lal of Centre for Atmospheric Sciences, IIT, Delhi, Indian winters may experience a decline of five to 25 per cent in rainfall. This could lead to drought during dry summer months. |
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Lal predicts that the date of the onset of the summer monsoon over central India could become more variable in future. More intense rainfall spells are projected in a warmer atmosphere. |
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If rainfall decreases, water flow of rain-fed rivers will decrease. This will affect groundwater recharge (see graph: Erratic rains). |
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Increase in rainfall might aggravate flood situations, bringing destruction and disease. | |
Since 1871, at least half the severe failures of the Indian summer monsoons have occurred in years of El Niño events. With increasing global temperatures, El Niño events are becoming more frequent and a higher frequency of drought conditions in some parts of India may follow. | |
A rise in sea surface temperatures may be accompanied by an increase in tropical cyclone intensities. According to IPCC, the intensity may go up by 10-20 per cent in the event of a 2-4°C increase in sea surface temperature leading to storm surges along the eastern coast of India. |
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The Himalayan glaciers, which feed many north Indian rivers and are the largest body of ice outside the polar regions, have been shrinking at an accelerated rate. According to Worldwatch, a US-based organisation, about 2,000 glaciers in the eastern Himalaya have completely disappeared in the last century. The Pindari glacier is receding at a rate of 13 metre a year while the Gangotri glacier is retreating at an annual rate of 30 metre. Warming is likely to increase the melting far more rapidly than accumulation of snow. |
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Glacial melt is expected to increase under changed climatic conditions which will lead to an increase in summer flows in some river systems for a few decades followed by a reduction in flow as glaciers disappear. As the rate of glacier melting gets higher, flash floods can be expected. |
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Rivers provide India with hydropower. The last decade has seen rapid deforestation, change in agricultural practices and urbanisation in mountainous region. This has led to frequent hydrological disasters, change in rainfall and runoff, extensive reservoir sedimentation and pollution of lakes. Global warming poses an additional threat to this region, which can harm power production. |
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l Most of the Himalayan glaciers depend on both summer and winter precipitation, making them more sensitive to temperature variations than any other glaciers. Intense rainfall enhances melting of glaciers and late snowfall in winters does not give enough time for ice-formation. An intensified monsoon and high temperatures thus lead to retreating and thinning of glaciers, increasing the risk of flash floods. |
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River deltas will see incursion of salt water as sea levels rise affecting agriculture. |
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