Future U.S. Wildfire Potential Trends Projected using Dynamically Downscaled Climate Change Scenarios

Climate is a major factor for wildfires along with fuel properties and topography. Global climate models have projected overall warming worldwide and more frequent droughts in many subtropical and mid-latitude regions including the U.S. It is likely that wildfires will increase in these regions. This study projects and analyzes spatial and seasonal patterns of future wildfire potential (the possible severity of a fire season, or a portion of the fire season for a region) in the United States. An approach was used to quantitatively estimate future increase/decrease in fire severity based on shift among the four levels of the Keetch-Byram Drought Index (KBDI) values, and lengthening / shortening of fire season based on the number of months of a year at or above a certain level. The KBDI was calculated and compared with present climate conditions and future change scenarios obtained from the North American Regional Climate Change Assessment Program. The results indicate that the U.S. is one of the global regions to show large increase in future wildfire potential. Significant wildfire potential increase is expected all seasons in the Rocky Mountains and during summer and fall seasons in the South. Wildfire potential severity is likely to move up by one level and fire season could be a few months longer in some areas.