Air Pollution and Climate Change: In Search of Co-Benefits

Since I’m getting ready to teach Air Pollution Law & Policy again this spring, I was keenly interested in hearing about the linkages between conventional air pollution and climate change.  So, I joined another packed session and heard representatives from the U.S. Environmental Protection Agency, Swedish Environmental Protection Agency, and Clean Air Task Force give fascinating presentations on the potential for well-integrated policies to achieve “co-benefits,” a fancy word for killing multiple birds with one stone and achieving benefits relating to climate, public health, and ecological systems all at the same time.  At the risk of oversimplifying a complex subject, the presenters made it clear that some of the strongest co-benefits may be available through efforts to reduce emissions of NOx, N2O, black carbon, ozone and its precursors, and particulate matter and its precursors.  Since the public health risks from ozone and particulate matter are astronomical in Asia and the Pacific, the opportunities for co-benefits there are particularly great.  Similarly, since the public health risks from black carbon are greatest in South Asia, there are tremendous opportunities for co-benefits in that region.  The presenters were cautious to note, however, that sulfate reductions offer more of a mixed bag.  Reductions of SO2 help eliminate the well known harms to water bodies, forests, and crops associated with acid rain.  However, sulfate aerosols play a role in dampening the effects of climate change, so reductions of SO2 emissions should be coupled with even more aggressive measures to address climate change.