Large wildfire trends in the western United States, 1984-2011
The authors examined regional trends in large fire occurrence, total area burned, fire size, and day of year of ignition from 1984 to 2011. The authors also assessed trends in climate indicators including maximum temperature, precipitation, and the Palmer Drought Severity Index (PDSI).
The authors found positive trends in the number of large fires in most ecoregions of the western U.S. including the Arizona-New Mexico Mountains with an average increase of 0.6 large fires per year. The ecoregions with trends toward increased fire activity also concurrently displayed increasing trends in drought severity over the period of the analysis. While the authors acknowledge that it is difficult to directly correlate human-caused climate change and fire activity, they assert that regardless of cause, changes in fire activity are part of larger trends tied to higher temperature and drought that are likely to continue.