How Air Pollution Affects Climate & What We Can Do About It 

Anthropogenic emissions that lead to air pollution (particulate matter and ozone) are also large contributors to climate change. Unlike the well-mixed greenhouse gases, the spatial distribution of these emissions affects their climate impact. A better understanding of the role of aerosols and ozone in contributing to historical and projected future climate change provides insight into the relative importance of air pollutants versus well-mixed greenhouse gases, the role of uncertainties in forcing in creating uncertainties in regional climate projections, and the balance between efforts to improve air quality and mitigate climate change. I will discuss recent progress in understanding the role of aerosols and ozone and the implications for our understanding of climate sensitivity, of the recent slowdown in global warming, and of the benefits to both climate and human health that can be obtained by taking action to reduce air pollutant emissions.