Global-to-regional-scale Climate Modeling

long recognized.3-5 Consequently, there has been a growing interest in investigating what changes in air quality may be brought about by the possible future changes in climate. The common assumption has been that warmer temperatures accompanying climate change will enhance pollution. However, due to the complex interplay of meteorology and chemistry in the formation of pollutants such as PM2.5 and O3, the potential effects of climate change are difficult to quantify. An understanding of these effects would likely influence air quality management decisions. For example, to assess the effects of future emissions control policies, current regulatory practices rely on applying regional-scale photochemical modeling systems with a variety of different emissions scenarios, but identical meteorological conditions. However, because the assumption of constant meteorology for decades into the future is questionable, this method may result in emissions control plans falling short of achieving air quality standards. While the current focus of local emissions control plans is typically 5–10 years, regional-scale plans are now underway with timescales of more than 20 years. This article provides an overview of some recent advances in quantifying the effects of climate change on air quality. Because climate change affects the entire globe and many processes influencing local air quality occur over smaller distances, the modeling tools applied in these studies range from global to urban in scale. A companion article in this issue focuses on the effects of urbanand regional-scale air pollution on global climate.6