Rising temperatures and inadequate rainfall in India is stagnating grain output, threatening food security in the world’s second-most populous country, according to a weather scientist. In the past decade, average temperatures have increased by 0.25 degree Celsius when the monsoon crops are sown in June, and by 0.6 degree Celsius when winter crops are planted in October, said Krishna Kumar, a senior scientist at the Indian Institute of Tropical Meteorology, a state-owned researcher.

Prime Minister Manmohan Singh is counting on a bigger crops to tame inflation from a 17-month high and to meet an election promise of ensuring food security for the poor by providing rice and wheat at below market prices. India’s economy slowed in the quarter ended December after a drought last year ravaged crops and pushed global sugar prices to a 29-year high. “Warmer nights affect rice output while day temperatures hurt wheat production,” Kumar said in an interview on April 16 in the western city of Pune. “Night temperatures are increasing more rapidly than day temperatures since the late 1980s” due to rising human greenhouse-gas emissions, he said.

Dry weather caused by El Nino has raised concerns this year that output of rice in the Philippines and Thailand, palm oil in Malaysia and Indonesia, and coffee in Vietnam may be reduced. A drought in India pushed imports of sugar and cereal to a record last year. Warmer-than-normal weather in Pakistan led to food shortages causing nationwide riots, and reduced tea production in Sri Lanka, the world’s fourth-biggest grower. “The projected warming over the water-limited tropics is likely to further depress yields and exacerbate water scarcity, constraining attempts to increase grain production,” Cristina Milesi, a scientist at the California State University and at NASA Ames Research Center, said in a report last month.

Leading Example’ India’s population and the largest water-limited tropics croplands, makes it a “leading example of the observed declines in food grain production,” she said. The combined global land and sea-surface temperatures last month was 0.77 degrees more than the twentieth century average of 12.7 degrees, making March the warmest on record, according to the National Oceanic and Atmospheric Administration. March was also the hottest on record in India, government-owned India Meteorological Department, or IMD, said on its website.

The IMD may release its forecast for the June-to-September monsoon rains on April 20, D Sivananda Pai, a director, said on April 13. The prediction is among the most widely watched as more than 70 per cent of the country’s rainfall is monsoonal. The recent heat probably pared yields of India’s winter crop by 6 per cent, according to a report authored by Milesi, Kumar and four other scientists studying the impact of climate change on food grain production. Monsoon-sown crops of rice, sugar cane and oilseeds make up half of India’s grain output, with wheat and other winter crops accounting for the remainder. Benefits of a good monsoon on rice yields are nullified by rising nighttime temperatures and below average rains, as seen last year, worsens the impact, Kumar said.