Intercontinental trans-boundary contributions to ozone-induced crop yield losses in the Northern Hemisphere

[摘要] Using a global atmospheric chemistry model, we have quantified for the firsttime, intercontinental transboundary contributions to crop ozone exposure andsubsequent yield reductions in the Northern Hemisphere. We apply four metrics(AOT40, M7, M12, W126) to assess the impacts of 100% reductions inanthropogenic NO_x emissions from North (N) America, South East (SE)Asia and Europe on global and regional exposure of 6 major agricultural croptypes to surface ozone, and resultant crop production losses during the year2000 growing season. Using these metrics, model calculations show that forwheat, rice, cotton and potato, 100 % reductions in SE Asian anthropogenicNO_x emissions tend to produce the greatest global reduction in cropproduction losses (42.3–95.2%), and a 100 % reduction to N~Americananthropogenic NO_x emissions results in the greatest global impact oncrop production losses for maize and soybean (59.2–85.9%). A 100%reduction in N~American anthropogenic NO_x emissions produces thelargest transboundary impact, resulting in European production lossreductions of between 14.2% and 63.2%. European NO_x emissionstend to produce a smaller transboundary impact, due to inefficiency oftransport from the European domain. The threshold nature of the AOT40 ozone-exposuremetric results in strong dependence of non-local emissions impacts on the localozone concentration distribution. Ourcalculations of absolute crop production change under emission reductionscenarios differ between the metrics used, however we find the relativeimportance of each region's transboundary impact remains robust betweenmetrics. Our results demonstrate that local air quality and emission controlstrategies have the potential to partly alleviate ozone-induced crop yieldloss in continents downstream, in addition to effectively mitigating localozone-induced production losses.

[学科分类] 地球化学与岩石