A recent article in the Proceedings of National Academy of Sciences has deduced that air pollution and global climate change is having anegative effect on the rice crops in India. The article is titled Integrated model shows that atmospheric brown clouds and greenhouse gases have reduced rice harvests in India, and is available at the PNAS website (the picture here is a satellite image of the brown clouds seen over the Indian Ocean).
It’s authors include V. Ramanathan, who is an air pollution expert and also the lead author of a study conducted a few years ago showing that the dark clouds, containing dust and soot, above the Indian ocean were leading to faster rise in air temperatures. The dark clouds were absorbing the sun’s radiation and not just leading to temperature changes in the air, while simulataneously reducing the amount of radiation reaching the earth and causing changes in precipitation patterns. It does not take a genius to figure out that all the brown/black stuff in those clouds is mostly anthropogenic (human-created) in origin.
Previous studies have found that atmospheric brown clouds partially offset the warming effects of greenhouse gases. This finding suggests a tradeoff between the impacts of reducing emissions of aerosols and greenhouse gases. Results from a statistical model of historical rice harvests in India, coupled with regional climate scenarios from a parallel climate model, indicate that joint reductions in brown clouds and greenhouse gases would in fact have complementary, positive impacts on harvests. The results also imply that adverse climate changes due to brown clouds and greenhouse gases contributed to the slowdown in harvest growth that occurred during the past two decades.
This paper provides high quality data on projections for rice harvest, a major food crop in that part of the world – feeding billions – when local climate changes due to the warming effects of brown clouds are included in the models.
The authors found that historical rice harvests would have been larger in the absence of the clouds, and larger still if reductions in the clouds were accompanied by reductions in greenhouse gases. Contrary to previous concerns that reducing the brown clouds could diminish harvests by unveiling the warming effects of greenhouse gases, these results suggest that reductions in these clouds, alone or in combination with reductions in greenhouse gases, would benefit rice harvests in India.