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Field measurements and modeling have examined how temperature, precipitation, and exposure to carbon dioxide (CO2) and ozone affect major staple crops around the world. Most prior studies, however, have incorporated only a subset of these influences. Here we examine how emissions of each individual pollutant driving changes in these four factors affect present-day yields of wheat, maize (corn), and rice worldwide. Our statistical modeling indicates that for the global mean, climate and composition changes have decreased wheat and maize yields substantially whereas rice yields have increased. Well-mixed greenhouse gasses drive most of the impacts, though aerosol-induced cooling can be important, particularly for more polluted area including India and China. Maize yield losses are most strongly attributable to methane emissions (via both temperature and ozone). In tropical areas, wheat yield losses are primarily driven by CO2 (via temperature), whereas in temperate zones other well-mixed greenhouse gases dominate. Rice yields increase in tropical countries due to a larger impact from CO2 fertilization plus aerosol-induced cooling than losses due to CO2-induced warming and impacts of non-CO2 gasses, whereas there are net losses in temperate zones driven largely by methane and other non-CO2 gasses. Though further work is needed, particularly on the effects of aerosol changes and on nutritional impacts, these results suggest that crop yields over coming decades will be strongly influenced by changes in non-CO2 greenhouse gasses, ozone precursors, and aerosols and that these should be taking into account in plant-level models and when examining linkages between climate change mitigation and sustainable development.

Plain Language Summary Changes in both climate and atmospheric composition are known to affect crop yields, but as both these factors are driven by a variety of emissions, it is not obvious what is the net effect of individual pollutant emissions on food supplies. Here we use a statistical crop model based on extensive field studies and modeling along with results from climate and composition response simulations to evaluate the net impact of individual emissions from human activities on three major staple crops: wheat, maize (corn), and rice. We find that although carbon dioxide dominates climate change to date, other pollutants play a large role in driving crop yield changes, sometimes dominating overall impacts. This suggests that efforts to mitigation climate change or improve air quality will have distinct effects on agriculture, depending on which pollutants are targeted; that local benefits might be maximized by targeting specific pollutants; and that projections of future climate should pay close attention to the role of non-CO2 emissions including taking into account their effects of air quality.