How will climate change impact the Indian monsoon? This is a question for which there is yet no clear-cut answer. A general perception among the climatologists is that the total annual rainfall in India may increase due to global warming-driven surge in moisture load of the atmosphere. That may seem to be a positive factor. But, at the same time, incidence of extreme rainy bouts of the kind witnessed in Uttarakhand recently are also projected to become more frequent, which can be perilous. The indications are that these changes will vary in different regions and will be accompanied by a rise in temperature. The agriculture sector is bound to be affected by these variations.
A fresh study of the past performance of the monsoon and the probable impact of the emerging rainfall pattern on Indian agriculture by a weather scientist M Rajeevan, advisor to the ministry of earth sciences, puts this issue in cogent perspective. It does not notice any well-defined long-term trends in the time series data of the average annual monsoon rainfall in India between 1901 and 2012. But it does find significant regional deviations. What stands out distinctly are the episodes of above or below normal rainfall lasting for several decades at a stretch. Of prime concern is the recent phase of below-average rainfall beginning around the mid-1970s that has followed an equally protracted wet period, going back to the 1930s.
This phenomenon assumes significance, when considered along with the uptrend in surface air temperature. The time series data on annual average temperature between 1901 and 2011 shows a trend rise of 0.56 degree Celsius per 100 years. This is close to the global warming trend.
"There is substantial increase in surface temperature since the mid 1970s," says Rajeevan in his paper published in a book entitled "Climate change and sustainable food security". It has been brought out jointly by the Bangalore-based National Institute of Advanced Studies and the Indian Council of Agricultural Research (ICAR). The paper adds that the surface warming (temperature rise) is noticeable over most parts of the country, barring some pockets in the northwest. The night temperatures have increased sharply in recent years, highlighting the role of greenhouse gases.
Such changes in the climate may influence crop farming in four ways. First, the alterations in temperature and rainfall may alter the present demarcation of the country's agro-ecological zones. Enhanced evapo-transpiration is likely to intensify drought stress, especially in the semi-tropics and subtropics. Second, the changed carbon dioxide content of the atmosphere may benefit crops due to a higher rate of photosynthesis and more efficient water use. Third, water availability (or run-off) and length of growing season may affect the agriculture negatively or positively in different areas. And fourth, overall crop losses may be exacerbated due to variable climate and increased frequency of extreme events, including droughts and floods, and changes in precipitation and temperature.
However, the Indian farm scientists, as also the vast national agricultural research network, one of the largest in the world, seem confident to take the emerging challenges head on. ICAR director-general S Ayyapan has asserted that strategies are already in place to reorient and strengthen basic research and accelerate the flow of technology. Special focus is on developing situation-specific integrated farming systems, involving animal husbandry and fisheries for arid areas, coastal and hilly regions, and irrigated and rainfed farming. Development of models for climate-resilient agriculture and evolution of drought and heat tolerant mechanisms for managing crops and farm animals are among the 12th Plan's priorities for farm research.
The success of these efforts would, however, rely crucially on raising the funding for agricultural research from the current meagre 0.6 per cent of the farm sector's gross domestic product (agricultural GDP) to 1.0 per cent in the short run and 2.0 per cent later on. The fact that also needs to be borne in mind is that the Indian agriculture has managed to adjust and adapt itself to changing circumstances over the centuries, when there was hardly any support from organised research. Now that well-directed research & development backing is available, there is no reason it would not be able to face the stress and strains due to climate change.