Fires Seen Making Climate Change Worse
Date: 24-Apr-09
Country: US
Author: Deborah Zabarenko, Environment Correspondent
Fires Seen Making Climate Change Worse Photo: Gene Blevins
Fire lights up the night over houses on the second day of
a wildfire in Sylmar, California October 13, 2008.
Photo: Gene Blevins
WASHINGTON - In a vicious cycle made worse by humans, scientists now believe
fires spur climate change, which in turn makes blazes bigger, more frequent
and more damaging to the environment.
Climate experts have known that a warmer world would spawn more fires, but
in research published on Thursday in the journal Science, scientists
reported that fires -- especially those set by humans to clear forests --
influence climate change.
Smoke particles sent into the atmosphere by fires inhibit rainfall, which
makes the land drier and encourages more fires to start, said study
co-author Jennifer Balch of the University of Santa Barbara in California.
On a global scale, burning releases vast amounts of heat-trapping greenhouse
gases like carbon dioxide, making fires more likely in a warming world,
Balch said in a video news briefing.
The report's authors estimate that greenhouse emissions from the world's
fires equal about 50 percent of emissions that come from the burning of
fossil fuels.
Deforestation fires, like those set to clear forest for pasture in tropical
areas like the Amazon, are part of an unintentional "extreme experiment,"
Balch said: "We're testing how burning forests will influence the climate
system."
"THE SCARY BIT"
These deliberately set forest fires contributed up to one-fifth of all
human-generated warming in industrial times, she said.
The climate-fire cycle works like this: plants store the climate-warming gas
carbon dioxide; when they burn, they release the gas into the atmosphere,
which contributes to global warming.
The more fires, the more carbon dioxide is released, which in turn causes
more warming in a cycle scientists call positive feedback.
"The scary bit is that, because of the feedbacks and other uncertainties, we
could be way underestimating the role of fire in driving future climate
change," said co-author Thomas Swetnam of the University of Arizona in
Tucson.
This important piece of the climate change puzzle has not previously been
emphasized, said co-author David Bowman of the University of Tasmania in
Hobart, Australia.
Most climate scientists considered fire to be a natural disturbance that was
not a crucial force that should be considered in creating models of how the
planet's climate will change, Bowman said.
"Humans and fire have a complex and ancient relationship," Bowman said. "The
relationship means that we can manage fire but we can also start fires. A
citizen can't create hurricanes, but a citizen (who sets a fire) can create
a mass disaster."
The report's 22 authors called on the U.N. Intergovernmental Panel on
Climate Change to take the role of fire into account when making future
climate models.
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