Recent climate and air pollution impacts on Indian agriculture

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-11, Vol.111 (46), p.16319-16324
• Main Authors: Burney, Jennifer, Ramanathan, V.
• Format: Article
• Language: English
• Subjects: Aerosols; Agriculture - statistics & numerical data; Agriculture - trends; Air Pollutants - toxicity; Air Pollution; Biological Sciences; Carbon - toxicity; Carbon dioxide emissions; Climate Change; Climate models; Crops; Crops, Agricultural - drug effects; Crops, Agricultural - growth & development; Emissions; Formaldehyde - toxicity; Greenhouse Effect; Greenhouse gases; Growing seasons; Impact analysis; India; Methane - toxicity; Models, Theoretical; Nitrogen Dioxide - toxicity; Oryza - drug effects; Oryza - growth & development; Oryza sativa; Ozone; Ozone - toxicity; Physical Sciences; Pollutant emissions; Pollutants; Rain; Rice; Seasons; Temperature; Triticum - drug effects; Triticum - growth & development; Triticum aestivum; Wheat
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1317275111

Significance Rising temperatures because of increased emissions of long-lived greenhouse gases (LLGHGs) have had and will continue to have significant negative impacts on crop yields. However, other climate changes caused by short-lived climate pollutants (SLCPs) are also significant for agricultural productivity. The SLCPs black carbon and ozone impact temperature, precipitation, radiation, and—in the case of ozone—are directly toxic to plants. To our knowledge, this study provides the first integrated historical examination of the role of both SLCPs and LLGHGs on wheat and rice yields in India, and finds that the majority of losses are attributable to SLCPs. Agricultural cobenefits from SLCP mitigation are expected to be large, and because SLCPs have short atmospheric lifetimes, almost immediate. Recent research on the agricultural impacts of climate change has primarily focused on the roles of temperature and precipitation. These studies show that India has already been negatively affected by recent climate trends. However, anthropogenic climate changes are a result of both global emissions of long-lived greenhouse gases (LLGHGs) and other short-lived climate pollutants (SLCPs). Two potent SLCPs, tropospheric ozone and black carbon, have direct effects on crop yields beyond their indirect effects through climate; emissions of black carbon and ozone precursors have risen dramatically in India over the past three decades. Here, to our knowledge for the first time, we present results of the combined effects of climate change and the direct effects of SLCPs on wheat and rice yields in India from 1980 to 2010. 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. [Our point estimates for rice (−20%) are similarly large, but not statistically significant.] Upper-bound estimates suggest that an overwhelming fraction (90%) of these losses is due to the direct effects of SLCPs. Gains from addressing regional air pollution could thus counter expected future yield losses resulting from direct climate change effects of LLGHGs.