Global Warming gets tagged for increased frequency and destructive character of wildfires:
Science News Online
Week of July 8, 2006; Vol. 170, No. 2 , p. 19
Major forest fires in the western United States have become more frequent and destructive over the past 2 decades. The trend has occurred in step with rising average temperatures in the region.
… Western snow packs now typically melt a week to a month earlier than they did half a century ago, recent studies have shown.
The northern Rockies have borne the brunt of the shift in fire patterns. In 1988, midsummer infernos torched 600,000 hectares in and around Yellowstone National Park; 25,000 firefighters battled the blaze, which continued until that winter's first snows fell.
About three-fifths of the largest U.S. wildfires since then have struck the same region. Government agencies spend up to $1.7 billion per year on wildfire control, and annual damages sometimes exceed $1 billion.
To understand the factors behind this mounting hazard, Swetnam and three colleagues examined fire, weather, and snowmelt data from 1970 to 2003.
For each year, the number and total area of major forest fires closely correlated with average spring and summer temperatures and with the date on which snowmelt peaked, reports the team, which was led by Anthony Westerling of the Scripps Institution of Oceanography in La Jolla, Calif.
Since 1987, fires have burned 6.5 times as much area per year as they did between 1970 and 1986, the researchers report in an upcoming Science. The average temperature increased 0.87°C between the two periods, and the average length of the fire season grew by 78 days.
"Warmer temperatures seem to be increasing the duration and intensity of the wildfire season in the western United States," comments ecologist Steven Running of the University of Montana in Missoula. …
… Fire-control efforts need to be adjusted accordingly … says Constance I. Millar of the U.S. Forest Service in Albany, Calif.
Published Online July 6, 2006
Science DOI: 10.1126/science.1128834
Submitted on April 17, 2006
Accepted on June 28, 2006
Warming and Earlier Spring Increases Western U.S. Forest Wildfire Activity
Anthony Leroy Westerling, Hugo G. Hidalgo, Daniel R. Cayan, Thomas W. Swetnam
[Abstract and link to PDF]