The impact of climate change on fire weather over North America as projected by multiple regional climate models in NARCCAP

The impact of climate change on fire weather over North America is investigated in terms of changes in the Haines Index between the current and future climate. The Haines Index is a fire weather index used as an indicator of the potential for dry, low-static stability air in the lower troposphere to contribute to erratic fire behavior or large fire growth. In this study, the Haines Index is calculated using outputs from a suite of multiple regional climate models (RCMs) driven by multiple general circulation models (GCMs) that have been made available by the North American Regional Climate Change Assessment Program (NARCCAP). The NARCCAP RCM simulations are run at 50 km grid spacing and for the A2 emissions scenario. The spatial distribution and seasonal variation of the Haines Index and its two components (stability and dryness of the lower troposphere) for the current (1971-2000) and future (2041-2070) climate are compared. Despite the differences in the projections made by different RCM-GCM combinations, the results show that future climate conditions will likely to favor more frequent occurrences of days with high Haines Index and that the consecutive days with high Haines Index will likely to be longer over most regions of North America.