Projections of Future Changes in Surface Ozone Concentrations Over the United States, Effects of Pollutant Transport, and Uncertainty Analyses
This research analyzes potential U.S. ozone changes from the present time period (1996-2000) to the mid (2048-2052) and late (2095-2099) 21 St century. Included in the analysis is a systematic evaluation of the individual and combined effects of climate change, resulting changes in biogenic precursor emissions, and changes in anthropogenic precursor emissions within and outside the contiguous U.S. territory. Considering the uncertainties in ozone projections, two cases of potential changes in climate and precursor emissions are compared, including the IPCC SRES A1fi (high emissions) and B1 (low emissions) scenarios. The two scenarios were chosen as representative of the current understanding of the upper and lower ends of potential climate changes over the coming century. The analyses of future ozone projections are based on results from the global chemical-transport model, Model for OZone And Related chemical Tracers version 2.4, driven by meteorological fields from a state-of-the-art climate model, namely the Parallel Climate Model. It is found that potential changes in U.S. ozone concentrations would be influenced most significantly by changes in anthropogenic emissions both inside and outside the U.S. In addition, changes in methane concentrations and climate-induced biogenic emissions could have large impacts on future U.S. air quality. Projected changes in climate suggest there likely will be increasing surface ozone levels over many inland regions. Hence, policies to slow down global climate changes along with enhancing the controls on precursor emissions are critical for preventing further issues with ozone pollution over much of the United States.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign