It is increasingly recognized that the science and policy communities need to explore the potential impact of long-term (multi-decadal), global climate change on regional air qualityspecifically the possibility that such change may complicate air quality managers ability to attain their management goals. These concerns are grounded in information derived from observational studies, basic atmospheric chemistry, and modeling of short-term air pollution episodes. For example, these analyses have established the major role that weather patterns play in establishing conditions conducive to ozone (O3) formation and accumulation, such as abundant sunshine, high temperatures, and stagnant air. It is now well understood that year-to-year variability in summer climate is strongly correlated with the number of days that exceed O3 air quality standards. Historically, air pollution has been studied mostly in terms of immediate local and regional concerns, rather than as a global change issue. In 2001, the EPA Office of Research and Developments Global Change Research Program initiated an effort to increase understanding of the multiple complex interactions between long-term global climate change and atmospheric chemistry which have the potential to influence air pollution in the United States. The overall goal of the assessment effort is to enhance the ability of air quality policy makers and managers to consider global climate change in their decisions through this increased understanding.

"EPA/600/R-07/094F." "April 2009" Title from title screen (viewed on April 20, 2009). Includes bibliographical references.

Summary of policy relevant findings -- Introduction to the problem -- Major themes of the interim assessment report -- Background -- Design of the global change and air quality assessment -- Client communities -- Considering uncertainty in the assessment effort -- Structure of this report -- Overview of approach -- Workshop recommendations -- Research partnerships -- Results and synthesis -- Summary of results from individual groups -- GCTM-focused modeling work -- Linked global-regional-focused modeling work -- Synthesis of results across groups -- Regional modeling results -- Global modeling results -- Challenges and limitations of the model-based approach -- Synthesis conclusions and future research needs -- Future directions -- Phase II of the global change and air quality assessment -- Extending the modeling systems -- Relative impacts of climate and emissions changes: preliminary work -- Modeling the drivers of air pollutant emissions -- Appendices: Glossary of climate and air quality terms -- current U.S. regional air quality, its sensitivity to meteorology and early studies of the effect of climate change on air quality -- 2001 EPA Global Change Research Program's Air Quality Expert Workshop -- U.S. EPA Star Grant research contributing to the GCAQ assessment -- Modeling approach for intramural project on climate impacts on regional air quality -- Using MARKAL to generate emissions growth projections for the EPA Global Change Research Program's air quality assessment -- Characterizing and communicating uncertainty: the November 2006 workshop.