Pollution haze blamed for India’s declining rice yields: research

Pollution haze blamed for India’s declining rice yields: research

5 December 2006

published by www.earthtimes.org

India — Atmospheric brown-clouds bearing pollutants have been blamed for the reduction in India’s rice yields from the mid-1980s to 1998.

Researchers working for the University of California on Monday said that reducing human-generated air pollution would help reverse some of the harm done to India’s rice harvest.

Providing the country’s agricultural data, their study shows that rice yields had been on a decline after surging to an all-time high in the 1960s and 1970s. An analysis revealed the declining yield was caused by two environmental factors – atmospheric brown clouds and global warming.

Atmospheric brown clouds are the brownish haze (found over much of South Asia), generally composed of soot and other pollutants mostly produced from burning fossil fuels. In the region these clouds are known as ‘Asian Haze’. Researcher Maximillian Auffhammer said “if there had been no atmospheric brown clouds between 1985 and 1998, the annual rice harvest yield would have been 11 percent higher than it was.”

The other factor greenhouse gases that threaten to accelerate global warming also contributed to the annual declines in rice crop. Greenhouse gases such as carbon dioxide and methane are released into the atmosphere by automobiles, coal fired energy plants and toxic gas-spewing industries.

Auffhammer and co-researchers V. Ramanathan and Jeffrey Vincent analyzed historical agricultural data against climate models. They observed that the brown clouds blocked much sunlight from the rice producing regions. This in turn caused cooler and dimmer conditions unsuitable for rice cultivation. They point out that cooler night-time conditions caused by the clouds would otherwise benefit the crop but the harm they do is far greater.

The US team’s findings get support from another recent study that said the Asian Haze was also responsible for less rainfall. Co-author Vincent who is also an economist said most air pollution control efforts so far had been driven by concerns about the health of India’s urban population. This study “provides an additional motivation related to the economic health of poor rural areas”.

The study was limited to Indian states that are largely dependent on rainfall. The report is published in the current issue of the journal Proceedings of the National Academy ofSciences.

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