Surface ozone impacts on major crop production in China from 2010 to 2017

Abstract

Abstract. Exposure to elevated surface ozone is damaging to crops. In this study, we performed an analysis of temporal and spatial distributions of relative yield losses (RYLs) attributable to surface ozone for major crops in China from 2010 to 2017, by applying AOT40 metrics (hourly ozone concentration over a threshold of 40 ppbv during the growing season) simulated using a chemical transport model. The major crops in China include wheat, rice (including double early and late rice, and single rice), maize (including north and south maize), and soybean. The aggregated production and associated economic losses in China and major provinces were evaluated by combing annual crop production yields and crop market prices. We estimated that the national annual average AOT40 in China increased from 21.98 ppm h in 2010 to 23.85 ppm h in 2017, with a peak value of 35.69 ppm h in 2014, as simulated with the model. There is significant spatial heterogeneity for the AOT40 and RYLs across the four crops due to the seasonal ozone variations. We calculated that national mean RYLs for wheat, rice, maize, and soybean were 11.45 %–19.74 %, 7.59 %–9.29 %, 0.07 %–3.35 %, and 6.51 %–9.92 %, respectively, from 2010 to 2017. The associated crop yield losses were estimated at 13.81–36.51, 16.89–20.03, 4.59–8.17, and 1.09–1.84 million metric tons (Mt) respectively, which accounted for annual average economic loss of USD 9.55 billion, USD 8.53 billion, USD 2.23 billion, and USD 1.16 billion individually over the 8 years. Our study provides the first long-term quantitative estimation of crop yield losses and their economic cost from surface ozone exposure in China before and after the China Clean Air Act in 2013, and improves understanding of the spatial sensitivity of Chinese crops to ozone impacts.