资源环境科技发展态势分析平台

The impact of ground-level ozone (O-3) on vegetation is largely under-investigated at the global scale despite large areas worldwide that are exposed to high surface O-3 levels. To explore future potential impacts of O-3 on vegetation, we compared historical and projected surface O-3 concentrations simulated by six global atmospheric chemistry transport models on the basis of three representative concentration pathways emission scenarios (i.e. RCP2.6, 4.5, 8.5). To assess changes in the potential surface O-3 threat to vegetation at the global scale, we used the AOT40 metric. Results point out a significant exceedance of AOT40 in comparison with the recommendations of UNECE for the protection of vegetation. In fact, many areas of the Northern Hemisphere show that AOT40-based critical levels will be exceeded by a factor of at least 10 under RCP8.5. Changes in surface O-3 by 2100 worldwide range from about +4-5 ppb in the RCP8.5 scenario to reductions of about 2-10 ppb in the most optimistic scenario, RCP2.6. The risk of O-3 injury for vegetation, through the potential O-3 impact on photosynthetic assimilation, decreased by 61 and 47% under RCP2.6 and RCP4.5, respectively, and increased by 70% under RCP8.5. Key biodiversity areas in southern and northern Asia, central Africa and North America were identified as being at risk from high O-3 concentrations.