Air pollution lowers crop yield: study

Much of the drop in yield came from air pollution caused by fine particles like soot as well as ozone generated by sunlight acting on emissions of precursor molecules.

There is substantial variation across States in the relative impacts produced by climatic factors and air pollution on crop yields. File Photo: K.K. Mustafah

India’s food grain production is facing a double whammy, with heightened air pollution adding to the impact of climate change on crop yields, according to a recent study.

“Our statistical model suggests that, averaged over India, yields in 2010 were up to 36% lower for wheat than they otherwise would have been, absent climate and pollutant emissions trends, with some densely populated States experiencing 50% relative yield losses,” observed Jennifer Burney of the University of California at San Diego in the U.S. and V. Ramanathan of the Scripps Institution of Oceanography, also in San Diego, in a paper in the Proceedings of the National Academy of Sciences (PNAS) .

They found that much of the drop in yield came from air pollution caused by fine particles like soot as well as ozone generated by sunlight acting on emissions of precursor molecules.

There was substantial variation across States in the relative impacts produced by climatic factors and air pollution on crop yields.

In Uttar Pradesh and Uttarakhand, wheat yields were about half of what they otherwise could have been, with air pollution responsible over two-thirds of the drop. Wheat yields in Rajasthan, Madhya Pradesh, Chhattisgarh, Bihar and Jharkhand too had been greatly reduced by air pollutants, according to the paper.

However, there was little or no impact from either a changing climate or pollution on wheat yields in Punjab or Haryana, although their rice yields had been affected. Rice yields have been lowered in Uttar Pradesh, Uttarakhand, Bihar, Jharkhand and West Bengal by 15 per cent or more.

“Cleaning up the air could have very positive benefits for agriculture and food security in India (along with all the other benefits of better air quality),” remarked Dr. Burney in an email. Improved cook stoves along with better control over emissions from the transportation sector and in electricity generation would reduce levels of soot in the air as well as of ozone’s precursor compounds.

The results published in the paper had been obtained by using crop and pollutant emissions models, noted J. Srinivasan, who heads the Divecha Centre for Climate Change at the Indian Institute of Science in Bangalore.