Climate change is primarily attributable to an increase in greenhouse gases (GHGs) that warm the atmosphere by trapping heat radiating from the earth. Human activities resulting in constantly escalating use of energy ‘subsidies’ in the form of fossil fuels and also through more economically ‘productive’ land use changes are the primary reasons for increased GHGs. These gases cause aberrations in the global carbon cycle involving interaction among the atmosphere, oceans, soils and vegetation and fossil fuel deposits.
The increasing GHGs resulted in global warming by a modest 0.74°C over the past 100 years although 11 of the 12 warmest years occurred after 1995. The Intergovernmental Panel for Climate Change (IPCC) on temperature predicts an increase between 1.8 and 4°C from the current levels by the end of this century with a projection of about 0.2°C per decade for the next two decades. Even with all future emissions stopped, a further warming of about 0.1°C per decade is expected. Also, hot extremes, heat waves and heavy precipitation may become more frequent.
Although micro regions are likely to be affected differently in India, some generalizations may be attempted to understand the impacts of climate change. An annual mean surface temperature rise by the end of century, from 2.5 to 5°C with warming more pronounced in the northern parts of India is envisaged and some parts of northwest and southern India are predicted to turn somewhat cooler. A substantial rise in all India summer monsoon rainfall over all states is calculated except Punjab, Rajasthan and Tamil Nadu, where a slight decrease has been estimated. Rising extremes in maximum and minimum temperatures with substantial increases in precipitation over the west coast of India and west central India as well as the severity of droughts and intensity of floods in various parts of India is anticipated by climate change experts. Notwithstanding some disagreements on the exact nature of climatic changes in different parts of India, the available literature is unambiguous about extreme climatic events, spread across larger areas in the country.
In an optimistic scenario – increased CO2 would have positive physiological effects because of increased photosynthesis. Also, as the ratio of carbon to nitrogen is constant, a doubling of carbon would imply a higher storage of nitrogen in soils as nitrates – providing better yields. Thus quality of crops such as rice will become firmer under elevated CO2 environment.
On the downside global shortages of food grains are predicted and IPCC report and other global studies indicate a probability of 10 to 40 per cent loss in crop production in India with increases in temperature by 2080-2100. Vulnerability of farmland in semi arid tropics of developing countries already suffering low levels of productivity will increase, with the warming projected to push even more farmland into this zone. Also, small changes in temperature and rainfall would have a significant effect on quality of fruits, aromatic and medicinal plants impacting their prices and trade.
Region specific studies in India related to climate change and agriculture, although few, generally endorse a decline in agricultural output. Studies at the Indian Agricultural Research Institute (IARI) indicate the possibility of future loss of 4 to 5 million tonnes (MT) in wheat production with every 1°C rise of temperature throughout the growing period (but no adaptation benefits). Losses for other crops are expected to be relatively smaller, especially for the kharif crops. Rapidly melting glaciers in Himalayas may affect irrigation in the Indo Gangetic plains, negatively impacting food production. Although CO2 effects of climate change may lead to productivity increases for some irrigated crops, major agricultural production areas, particularly water stressed, are likely to be adversely affected.
There is a concern that fast growing economies of India and China register high rates of growth of carbon emissions. However, with technologies available to the developing countries, carbon emission control by these countries would be at the cost of their development whereas the developed countries have ‘free-ridden’ on the global climate change till very recently to achieve the current status of their development. India, in the negotiations of United Nations Framework for Convention of Climate Change (UNFCCC) has suggested that the ‘right’ to pollute the atmosphere be proportionate to countries’ population. Although unsustainable in the long term, the proposal certainly takes the North South debate on climate change to a level playing field.
Despite uneven contribution towards climate change – both in absolute and relative terms – tropical regions face a more severe negative impact on agriculture, leading them to address mitigation of, and adaptation to climate change proactively. Mitigation measures in India and China include energy efficiency and conservation, promotion of renewable energy and fuel substitution, abatement of air pollution, afforestation and development of wasteland etc. Creating an enabling environment towards adaptation to climate change is imperative to buttress the farmers’ livelihood with governmental support – despite arguments that propose that tillers have an intrinsic ability to adjust to the effects of change. Efficient infrastructure such as rural roads, electrification, irrigation facilities etc. give them the flexibility to adapt, state scholars. Increased effort to develop a variety of crops suitable for higher temperatures is urgently sought as India invests only about 0.5 per cent in agriculture as compared to an investment of 0.7 per cent in developing countries and 2 – 3 per cent in developed nations.