The area burned by wildfires in 11 Western states
could double by the end of the century if summer climate warms
by slightly more than a degree and a half, say researchers with
the U.S. Department of Agriculture Forest Service and Pacific Northwest
Climate Impacts Group at the University of Washington.
Wyoming and New Mexico appear acutely sensitive, especially
to temperature changes, and fire seasons there may respond more
dramatically to global warming than in states such as California
Researchers have developed statistical relationships
between observed climate and an 85-year record of fire extent
during the 20 th century and used them in conjunction with existing
global climate models.
"Models linking area burned in the Western states with fire-season
temperature predict that global warming will bring significant
increases in fire extent," said Donald McKenzie of the USDA
Forest Service's Pacific Wildland Fire Science Lab. "Such
increases could have consequences for threatened and endangered
species in ecosystems that experience increased fire because
many such species are already restricted to specialized and
McKenzie is lead author of "Climatic Change, Wildfire and
the August issue of Conservation Biology. His co-authors
are Ze'ev Gedalof of the University of Guelph in Ontario, David
Peterson of the USDA Forest Service and Philip Mote, UW climate
scientist and Washington state climatologist. All are members
of the UW's Pacific Northwest Climate Impacts Group.
of past climate and fire histories showed that the most important
variable is summer temperature, more important than precipitation
in most cases.
Using what is considered a low-end climate-change
scenario – a 1.6 degree increase in summer temperatures between
2070 and 2100 compared to temperatures from 1970 to 2000 –the
area burned will increase by 1.4 to five times in western states
except California and Nevada, where the increase isn't so great.
in California and Nevada appears to be relatively insensitive
to changes in summer climate and the total area burned in these
may not respond strongly to changed climate. Parts of Northern
California where warmer climate could affect the number and extent
of fires, for example, are offset by areas in Southern California
where fires are almost all caused by human activities and the
combination of high temperatures and dry air associated with the
winds, not temperature by itself, McKenzie says.
At the other
extreme are Montana, Wyoming and New Mexico. Montana is the most
sensitive, with the models predicting a 5-fold increase in mean
area burned over the observed range in climate, the authors write.
Washington and Oregon, the effects will be intermediate because
precipitation and temperature are both associated with fire extent
in these states, rather than temperature alone.
more extensive fires in forest ecosystems will likely reduce
the number and size of patches of older forests, the authors say.
of wild areas between forests, through which species might migrate
if their home territory goes up in flames, also could be affected,
"The winners after fires in these cases are the weedy, adaptive, quickly reproducing species," McKenzie says. "The
losers are the ones needing more stable environments."
For more information:
McKenzie, (206) 732-7824, firstname.lastname@example.org
Peterson, (206) 732-7812, Peterson@fs.fed.us
Mote, (206) 616-5346, email@example.com