Biogeosciences Discuss., 8, 8645-8691, 2011
© Author(s) 2011. This work is distributed
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This discussion paper has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG.
Intercontinental trans-boundary contributions to ozone-induced crop yield losses in the Northern Hemisphere
M. J. Hollaway1, S. R. Arnold1, A. J. Challinor1, and L. D. Emberson2
1Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
2Stockholm Environment Institute, University of York, York, UK

Abstract. Enhanced surface ozone concentrations are known to be harmful to vegetation, reducing crop growth and yields. Tropospheric ozone concentrations have increased steadily since pre-industrial times, driven by in-situ production from anthropogenic emissions of nitrogen oxides (NOx), CO and volatile organic compounds. Transport of ozone and its precursors between continents has been shown to contribute to surface ozone air quality exceedences in many regions of the Northern Hemisphere. Using a global atmospheric chemistry model, we have quantified for the first time, intercontinental contributions to crop ozone exposure and yield reduction in the Northern Hemisphere. We apply three metrics (AOT40/M7/M12) to assess the impacts of NOx emissions from each of the Northern Hemispheres three major industrialised regions (North (N) America, South East (SE) Asia and Europe) on global and regional exposure of 6 major agricultural crop types to harmful ozone concentrations, and the resultant yield losses during the 2000 growing season. Using these metrics, model calculations show that for wheat, rice, cotton and potato, 100 % reductions in SE Asian anthropogenic NOx emissions tend to produce the greatest global reduction in crop yield losses (48.8 to 94.7 %) with the same cuts to N American emissions resulting in the greatest global impact on crop yield reductions for maize and soybean (57.5 to 81.7 %). N American NOx emissions produce the largest transboundary impact, resulting in European yield loss reductions of between 12.4 % and 55.6 %, when a 100 % cut is applied to NOx emissions from the N American region. European NOx emissions tend to produce a smaller transboundary impact, due to inefficiency of transport from the European domain. The threshold nature of the AOT40 ozone-exposure metric, results in a strong dependence of the diagnosed impact from trans-boundary emissions on local ozone concentration. In addition, we find that in parts of the United States, biomass burning emissions may make important contributions to ozone-induced crop yield reductions. Our results demonstrate that local air quality and emission control strategies have the potential to partly alleviate ozone-induced crop yield loss in continents downstream, in addition to effectively mitigating local ozone-induced yield losses.

Citation: Hollaway, M. J., Arnold, S. R., Challinor, A. J., and Emberson, L. D.: Intercontinental trans-boundary contributions to ozone-induced crop yield losses in the Northern Hemisphere, Biogeosciences Discuss., 8, 8645-8691, doi:10.5194/bgd-8-8645-2011, 2011.
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