[Vision2020] Job Security For Local Fire Fighters

[Ted Moffett]

http://www.sciencemag.org/cgi/content/abstract/1128834v1?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=westerling+forest+fires&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT



Published Online July 6, 2006
*Science* DOI: 10.1126/science.1128834
 *Science* Express Index<http://www.sciencemag.org/sciencexpress/recent.dtl>
Research Articles

Submitted on April 17, 2006
Accepted on June 28, 2006

Warming and Earlier Spring Increases Western U.S. Forest Wildfire
Activity *Anthony
Leroy Westerling 1*, Hugo G. Hidalgo 2, Daniel R. Cayan 3, Thomas W. Swetnam
4 *

1 Scripps Institution of Oceanography, La Jolla, CA 92093, USA; University
of California, Merced, CA 95344, USA.
2 Scripps Institution of Oceanography, La Jolla, CA 92093, USA.
3 Scripps Institution of Oceanography, La Jolla, CA 92093, USA; US
Geological Survey, La Jolla, CA 92093, USA.
4 Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ 85721,
USA.

* To whom correspondence should be addressed.
Anthony Leroy Westerling , E-mail: awesterl at ucsd.edu

Western United States forest wildfire activity is widely thought to have
increased in recent decades, but surprisingly, the extent of recent changes
has never been systematically documented. Nor has it been established to
what degree climate may be driving regional changes in wildfire. Much of the
public and scientific discussion of changes in western United States
wildfire has focused rather on the effects of 19th and 20th century
land-use history.
We compiled a comprehensive database of large wildfires in western United
States forests since 1970 and compared it to hydro-climatic and land-surface
data. Here, we show that large wildfire activity increased suddenly and
dramatically in the mid-1980s, with higher large-wildfire frequency,
longer wildfire
durations, and longer wildfire seasons. The greatest increases occurred in
mid-elevation, Northern Rockies forests, where land-use histories have
relatively little effect on fire risks, and are strongly associated with
increased spring and summer temperatures and an earlier spring snowmelt.

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http://www.usatoday.com/weather/climate/2006-07-06-climate-fires_x.htm

Study links extended wildfire seasons to global warming

Updated 7/7/2006 9:10 AM ET
By Patrick O'Driscoll, USA TODAY

DENVER — The number and size of large forest fires in the West have grown
"suddenly and dramatically" in the past two decades in part because of
global warming, a study released Thursday says.

The scientific paper, posted online by the journal *Science*, says wildfire
season in Western states has grown up to 2½ months longer since 1987 because
of warmer spring temperatures and earlier, faster melting of mountain snow.
The timing of that annual snowmelt, a key source of the West's water, also
helps gauge the severity of wildfire season.

The study by scientists at the University of California-San Diego and the
University of Arizona does not address the cause of climate warming, only
the effect it has had on forest fires here. Climate change is caused by
gases that trap heat in the Earth's atmosphere. Scientists and politicians
debate how much of that heating is made worse by humans and the burning of
fossil fuels.

"We didn't set out to make a climate-change argument," says co-author
Anthony Westerling, a researcher at UC-San Diego's Scripps Institution of
Oceanography. "But it's easier to see how a further (rise) in temperature
under climate change would result in more frequent (wildfires) in these
severe years. You get early snowmelt, the soil and vegetation dry out
sooner, and you get a lot more fires, burning longer and getting bigger."

The paper analyzes 1,166 large forest fires (at least 1,000 acres each) from
1970 to 2004 on national forest and park land in the West. In the second
half of that period, 1987-2004, there were four times as many forest fires,
and 61/2 times as much land burned.

Co-author Tom Swetnam of Arizona's Laboratory of Tree-Ring Research says the
key shift was after 1987. Infrequent large fires that lasted a week or so
gave way to more frequent infernos that averaged five weeks. One of the
worst years was 1988, when almost one-third of Yellowstone National Park
burned until autumn. The climate effect is most dramatic in the northern
Rockies, which includes Yellowstone. The number of large fires in Idaho,
Montana and Wyoming has risen 60% since 1987.
Climate is the principal reason, Swetnam says. Forests in the northern
Rockies have not been as heavily managed to stop fires as most other places
in the West. Putting out more fires can lead to worse fires by leaving
unburned debris and unthinned groves. So human intervention is a factor,
along with warming, in the worsening of wildfires in many areas. But the
rising temperatures and dryness due to warming are the main factor in the
northern Rockies, Swetnam says.
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Vision2020 Post by Ted Moffett
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