In the study, reported in Proceedings of the National Academy of Sciences, the researchers used climate models and historical data concerning Indian rice harvests.
"We found 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," said Maximilian Auffhammer of the University of California, Berkeley.
Auffhammer noted that the cooler nighttime temperatures caused by the clouds were beneficial, but the decreased rainfall more than negated this benefit. Additionally, the cooler temperatures may have masked the effects of greenhouse gasses in the past.
The team's research suggested the increased greenhouse gasses in the atmosphere had also adversely affected the rice harvests. They reported that reducing the clouds alone, or reducing them in concert with lowered greenhouse gasses, would benefit rice output. The study only focused on farming regions that relied on rain for their crops, Auffhammer added, so the benefits would be less noticeable in areas with other irrigation options.
The research team announced that they would now look into studying China, Indonesia and other countries with polluted atmospheres.
"I think this research is crucial because it gives policymakers a lever to increase rice output," Auffhammer said, but the Indian Council of Agricultural Research stated that the research did not give it immediate cause for concern. Assistant Director General Dr. Shankar Nath Shukla said ICAR was more worried about other issues such as nutrients, rice varieties and water management.
###