Surface Ozone Pollution and Global Agriculture: Estimated Impacts and Strategies to Reduce Damages

Abstract

Field studies demonstrate that exposure to elevated concentrations of surface ozone (O3) causes substantial reductions in the yields of many crops, yet O3 pollution is often overlooked as a potentially significant threat to current and future agricultural production. This study quantifies the global impact of O3 on crop yields in the present (year 2000) and near future (2030) under optimistic and pessimistic scenarios of O3 pollution, as well as associated crop production and economic losses for three key staple crops (soybean, maize, and wheat). This study additionally examines the potential of two strategies to reduce O3-induced yield losses that supplement controls on conventional O3 precursors: (1) O3 mitigation via gradual reductions of methane (CH4), an important greenhouse gas and a precursor to tropospheric background O3 that to date has not been targeted for O3 abatement, and (2) adapting crops to elevated O3 by selecting cultivars with demonstrated O3 resistance relative to median-sensitivity varieties. Finally, this work contextualizes the estimated impact of O3 on global agricultural production with predicted climate change effects, and identifies regions of the world potentially at risk of reduced crop yields due to both O3 and climate change over the next few decades.

Results indicate that present-day O3-induced global crop yield reductions are substantial, ranging from 4-15% for wheat, 9-14% for soybean, and 2-6% for maize worth $11-18 billion annually (USD2000). In the high O3 pollution scenario, year 2030 crop yield losses could be further reduced from 2000 levels by 2-10% for wheat, 1-11% for soybean, and 2-3% for maize, worth an additional $6-17 billion in losses globally. Controls on traditional O3 precursors in the optimistic pollution scenario appear to prevent extensive additional yield reductions in 2030, but total yield losses could remain significant, particularly for O3 sensitive crops (up to 15-17% for wheat and soybean). We find that the supplemental policy of CH4 control (via its additional O3 reductions) could considerably increase year 2030 production of soybean, maize and wheat by the equivalent of ~2-8% from year 2000 levels, worth $3.5-15 billion worldwide. Choosing crop varieties with demonstrated O3 resistance relative to median sensitivity cultivars may improve year 2030 production of these crops by 12% from 2000 values, worth ~$22 billion globally. This work suggests that the negative impact of O3 on agriculture now and in the near future could exceed predicted climate change effects for some crops (based on climate impact estimates available in the literature), and that regions at risk of yield reductions due to both O3 exposure and climate change include both significant agricultural producers (e.g. India, Russia, Brazil, and China) and net food importers (e.g. the Middle East) with possibly major implications for global food security. Efforts to reduce surface O3 concentrations and adapt crops to elevated O3 therefore provide an excellent opportunity to increase global agricultural production without the environmental damage associated with traditional agricultural intensification techniques or additional land cultivation.