Eastern boreal North American wildfire risk of the past 7000 years: A model-data comparison

We present here a 7000-year wildfire reconstruction based on sedimentary charcoal series from five lakes located south of Hudson Bay in eastern boreal North America. The reconstruction shows a significant downward trend in the frequency of large fires from 0.0061 fire.yr(-1) ca. 5000 cal yr BP to 0.0033 fire.yr(-1) at present. Simulations of fire-season climate based on UK Universities Global Atmospheric Modelling Programme output and reconstructions based on proxy data both indicate a shift toward increasing available moisture in the region between the mid-Holocene and today. We infer that the diminishing trend in wildfire activity was ultimately caused by the steady orbitally driven reduction in summer insolation. Future higher temperatures not compensated for by significant precipitation increases will bring fire frequency back toward its upper limit, recorded between 6000 and 2000 cal yr BP. Citation: Hely, C., M. P. Girardin, A. A. Ali, C. Carcaillet, S. Brewer, and Y. Bergeron (2010), Eastern boreal North American wildfire risk of the past 7000 years: A model-data comparison, Geophys. Res. Lett., 37, L14709, doi: 10.1029/2010GL043706.