Simulating changes in fire occurrence, behavior, and effects in North America ecosystems under multiple future climate scenarios

The MAPSS team has generated simulations of future fire and its impacts on North American ecosystems using the MC1 dynamic general vegetation model (DGVM) and six new climate scenarios generated by three General Circulation Models (Canadian CGCM2, UK HadCM3, and Australian CSIRO Mk2) forced by two different emission scenarios (IPCC SRES A2 and B2). By 2100, the climate scenarios showed a projected temperature increase of about 6 oC in summer and 8 oC in winter for the A2 emissions scenario, compared to 4 oC and 6 oC for B2, respectively. Predicted changes in precipitation and humidity were, in general, not sufficient to compensate for increases in temperature, producing simulated seasonal levels of fuel moisture that were often lower than those during historical period. Drier fuels produced increases in simulated fire frequency over much of the continent. Increased fire intensity was simulated in those regions of the continent where increases in precipitation were sufficient to support higher production of woody fuels. Where the climate scenarios predicted declines in effective moisture, fire in conjunction with drought reduced woody fuels, leading to declines in fire intensity over time. Much of the simulated change in ecosystem properties such as lifeform composition and carbon sequestration were mediated by changes in the simulated fire regime under the different climate scenarios.