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By SETH BORENSTEIN,
AP Science Writer WASHINGTON - In one week, Southern California's wildfires spewed the
same amount of carbon dioxide _ the primary global warming gas _ as the
state's power plants and vehicles did, scientists figure.
A new study by two Colorado researchers shows that U.S. wildfires pump a
significant amount of the greenhouse gas into the air each year, more
than the state of Pennsylvania does. It raises questions about how
useful it is to plant trees to offset rising carbon dioxide emissions
and soothe environmental consciences. Because the California wildfires occurred just as the study was about to
be published, the researchers calculated how much carbon dioxide was
likely to come from the devastating blazes Oct. 19-26. It's a lot: 8.7
million tons. That's more than the state of Vermont produces in a year. And it's also
more than the 6 million tons estimated by California's air control
agency, which used a different calculation method. On average, wildfires in the United States each year pump 322 million
tons of carbon dioxide. That's about 5 percent of what the country emits
by burning fossil fuels, such as gasoline and coal, according to the new
research published online Thursday in the peer-reviewed journal Carbon
Balance and Management. "It is quite a big chunk," said study co-author Jason Neff of the
University of Colorado at Boulder. But he adds: "It's nothing compared
to our fossil fuels burning." Mostly when scientists look at carbon dioxide emissions, they spend
their time on the stuff that man adds to power industrial life. But Neff
and Christine Wiedinmyer at the National Center for Atmospheric Research
in Boulder, Colo., looked at forests, which act as a sponge and absorb
some of the carbon dioxide, but which also burn and produce it. "The problem is that what goes in, comes out," Neff said. In recent years, some people who want to compensate for their personal
contributions to global warming (from driving gas-guzzling cars or
heating huge houses) have paid groups to plant trees to soak up that
extra carbon in the air. It's called a carbon offset. Over several decades or centuries, replanted trees will capture some of
the gas, but the first few decades it will be at a reduced rate,
Wiedinmyer said. "There's a real danger here that in the offsetting program you feel
you've done your bit," said University of Victoria climate scientist
Andrew Weaver, who wasn't part of the study. "You've got to be a little
bit more creative than to think that you're going to solve global
warming by planting trees." In previous studies, scientists have shown that a general increase in
American wildfires _ but no one event _ is linked to global warming.
That raises the possibility of a self-feeding cycle, Wiedinmyer said. The scientists used satellite imagery, computer models and combustion
rates to determine how much carbon dioxide is released during a fire,
Wiedinmyer said. Last week, the California Air Resources Board estimated that just under
6 million tons of carbon dioxide were released by the recent fires. The
board estimates that for every acre burned, the carbon dioxide emissions
are equivalent to two cars driven for a year, said board spokesman
Stanley Young. More than half a million acres have burned in Southern
California. Young and Wiedinmyer said estimates do vary widely on scientific method. The paper finds remarkable differences state by state and month by
month. August is the worst month for carbon dioxide emissions from fires. The Western continental United States is responsible for more than
one-third of the country's carbon dioxide from fires. But Alaska is
king. Alaskan fires produce twice as much of the greenhouse gas than
burning fossil fuels in that state. Alaskan fires make up 27 percent of
the nation's yearly fire-related carbon dioxide emissions. In the Lower 48, California, Oregon, Idaho, Washington, Louisiana,
Montana, Georgia, Alabama, Florida, and Texas are top 10 emitters of
carbon dioxide through forest fires.
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