Expert: Warming Climate Fuels Mega-Fires
Scott Pelley Reports From The American West's Fire Lines On The Rising
Number Of Mega-Fires
Oct 21, 2007 CBS News

[ . . . ]

The severity of the burning and size of the fires caught the eye of
Tom Swetnam, one of the world's leading fire ecologists. He wanted to
know what's touched off this annual inferno and whether it's truly a
historic change.

At the University of Arizona, Swetnam keeps a remarkable woodpile,
comprised of the largest collection of tree rings in the world. His
rings go back 9,000 years, and each one of those rings captures one
year of climate history.

Swetnam found recent decades have been the hottest in 1,000 years. And
recently, he and a team of top climate scientists discovered something
else: a dramatic increase in fires high in the mountains, where fires
were rare.

"As the spring is arriving earlier because of warming conditions, the
snow on these high mountain areas is melting and running off. So the
logs and the branches and the tree needles all can dry out more
quickly and have a longer time period to be dry. And so there's a
longer time period and opportunity for fires to start," Swetnam says

"The spring comes earlier, so the fire season is just longer," Pelley
remarks.

"That's right. The fire season in the last 15 years or so has
increased more than two months over the whole Western U.S. So actually
78 days of average longer fire season in the last 15 years compared to
the previous 15 or 20 years," Swetnam says.

Swetnam says that climate change -- global warming -- has increased
temperatures in the West about one degree and that has caused four
times more fires. Swetnam and his colleagues published those findings
in the journal "Science," and the world's leading researchers on
climate change have endorsed their conclusions.

[ . . . ]

"We used to have forest soil here that might have been this deep," he
says, indicating about a foot of depth, "but now we're just down to
rock."

"So you're down to mineral and sort of a rock, sort of armored soil.
And that is not a good habitat for trees to re-establish," Swetnam
says.

"Where do you think all this is headed?" Pelley asks,

"As fires continue to burn, these mega-fires continue to burn, we may
see ultimately a majority, maybe more than half of the forest land
converting to other forest, other types of ecosystems," Swetnam says.

"Wait a minute. Did you just say that there's a reasonable chance we
could lose half of the forests in the West?" Pelley asks.

"Yes, within some decades to a century, as warming continues, and we
continue to get large scale fires," Swetnam replies.

Swetnam says that this is what we have to look forward to. He
estimates, in the Southwest alone, nearly two million acres of forest
are gone and won't come back for centuries. The hotshots are already
planning for the next fire season. In 2006, the feds spent $2 billion
on fire fighting, seven times more than just ten years ago.

"You know, there are a lot of people who don't believe in climate
change," Pelley remarks.

"You won't find them on the fire line in the American West anymore,"
Tom Boatner says. "'Cause we've had climate change beat into us over
the last ten or fifteen years. We know what we're seeing, and we're
dealing with a period of climate, in terms of temperature and humidity
and drought that's different than anything people have seen in our
lifetimes."

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