Effects of climate change on forest fires over North America and impact on U.S. air quality and visibility

Climate-driven changes in fire activity over North America will influence U.S. ozone air quality and visibility. We use a stepwise linear regression to develop a predictive relationship between area burned and temperature, relative humidity, wind-speed, precipitation, and drought indices from the Fire Weather Index (FWI) system for ecosystems over North America, including the continental United States, Alaska, and Canada. Using output of these predictive variables from the NASA/GISS general circulation model (GCM) we examine how area burned will change between the present day and 2050. Using the derived future area burned, we create a biomass burning emission inventory for aerosols and ozone precursors to drive a global chemical transport model (CTM) and predict future changes in aerosol and ozone pollution episodes over the United States. The best predictors for area burned are ecosytem dependent but typically include mean summer temperature and mean drought code. In forest ecosystems of the Western U.S. our regressions explain 50-60% of the variance in annual area burned. Our results show that the predicted increase in future wild fires will have important consequences for U.S. ozone air quality and visibility.