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Surinder Sud: Changing with the climate

Surinder Sud  |  New Delhi 

A series of ICAR studies on the impact of climate change can help farmers modify their cultivation patterns.

That climate change and agriculture are interrelated is well known. Agriculture contributes, albeit only partly, to global warming — by spewing greenhouse gases (GHGs) — and, in turn, gets affected by its consequences.

However, GHG emissions from different farm sectors and the effect of global warming on these sectors have not been quantified, except in a few cases, such as wheat. The New Delhi-based Indian Agricultural Research Institute (IARI) has estimated that annual wheat output may decline by 4 to 5 million tonnes with every 1° C rise in temperature. This gap is now sought to be bridged by various studies carried out by the Indian Council of Agricultural Research (ICAR ).

These studies give some idea about the emissions of GHGs like methane, nitrous oxide and carbon dioxide arising from paddy fields and farm animals. They also explain the impact of climate change on some crops and other farm sectors like fisheries.

The emissions from the country’s 42.21-million hectares where rice is being cultivated comprise about 2.07 Tg of methane (Tg is the unit of measurement of GHG emissions and is equivalent to 1012 grams), 0.19 Tg of nitrous oxide and 72.90 Tg of carbon dioxide, annually. However, the emission levels vary from region to region, depending on cultivation practices and the inherent carbon content of the soils.

The methane outflow from the paddy fields of some districts in West Bengal has been observed to be relatively high — this is due to the presence of higher organic carbon content in the soils and the rampant practice of keeping rice fields constantly submerged under water. Similarly, emission of nitrous oxide is higher in paddy fields in Andhra Pradesh and northern states because of application of high doses of nitrogenous fertilisers there.

On the whole, the eastern and southern parts of the country have a relatively higher global warming potential because of higher discharge of methane and carbon dioxide and the predominance of rice cultivation in these regions.

In the case of methane emissions from the livestock sector, it has been observed that though cross-bred cattle discharge relatively more methane per animal, the bulk of the total emissions is accounted for by buffaloes and indigenous cattle because of their far larger population. Of the total livestock sector’s GHGs emissions, female buffaloes contributed 59.6 per cent, indigenous cows 28.9 per cent and cross-bred cows 11.5 per cent. The total emissions from this sector are reckoned at 9.37 Tg — varying in different years from 7.26 Tg to 10.4 Tg.

As for the impact of global warming, studies conducted in Andhra Pradesh indicate that the rise in temperature will lead to an increase in the water requirement of crops like maize, groundnut, tur (pigeon pea) and cotton, though their growing duration will decrease by 1 to 2 weeks.

Studies on assessing the impact of climate change on coconut production in different agro-climatic zones indicate that this plantation crop will, by and large, benefit from global warming. Its productivity may rise by up to 4 per cent by 2020 and up to 10 per cent by 2050 in different regions.

The coconut plantations in Kerala, Maharashtra and parts of Tamil Nadu and Karnataka stand to benefit more than those elsewhere. The coconut yields in some other states such as Andhra Pradesh, Orissa and Gujarat may tend to decline marginally, by up to 2 per cent.

Some crops have already begun adjusting to climate change. Apple cultivation in Himachal Pradesh is a case in point. Since temperatures in the traditionally apple-producing regions of this hilly state have risen, with a simultaneous decline in rainfall, apple cultivation is shifting to the higher altitudes in Kinnaur and Lahaul and Spiti districts.

Similarly, in the case of marine fisheries, it has been observed that species like Indian mackerel have tried to adapt themselves to the warming of the ocean waters by shifting towards the northern latitudes where the warming is less pronounced. Sardines have tended to spend more time in the lower depths of the oceans to escape from warmer surface waters.

Such observations are significant as they can help farmers and fishermen modify their cultivation and fishing practices to mitigate the economic consequences of climate change.  

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First Published: Tue, August 11 2009. 00:52 IST