Are Wildfires Getting Worse?

Are the Santa Barbara, Calif., and Myrtle Beach, S.C., fires on either side of the nation an indication of what is to come this summer? Fire seasons are getting longer, and fires are seemingly becoming more destructive.

A 2006 study published in Science found that, “Since 1986, longer, warmer summers have resulted in a fourfold increase of major wildfires and a sixfold increase in the area of forest burned, compared to the period from 1970 to 1986. A similar increase in wildfire activity has been reported in Canada from 1920 to 1999.” 

Additionally, the study found that “the length of the active wildfire season (when fires are actually burning) in the western United States has increased by 78 days, and that the average burn duration of large fires has increased from 7.5 to 37.1 days.”

Two years ago, “60 Minutes” ran a piece that predicted an age of mega-fires. The story linked an increase in the number and intensity of fires to global warming and increased greenhouse concentrations that make fires larger.

“60 Minutes” reported:

“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 at least 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.”

You should know that not everyone buys this idea.

USA Today reported on a study that disagrees with the notion that climate contributes to fires:

“Although rising global temperatures could lead to much drier trees and forests around the world, that may not necessarily translate to an increased risk for wildfires, according to a new study in this month’s issue of Ecological Monographs.

“This somewhat contradicts other recent research, most of which has identified a link between global warming and the increasing likelihood of wildfires, including studies from Science in 2006 (Study links extended wildfire seasons to global warming) as well as the Intergovernmental Panel on Climate Change in 2007 (Is Earth near its ‘tipping points’ from global warming?).

“These studies indicated that wildfires in many parts of the world will increase over the next century as climate change lengthens the fire season, decreases moisture and increases ignition rates.

In this month’s study, however, scientists found that changes in vegetation trumped past climate changes in determining wildfire frequency.”

The Daily Green, an environmental Web site, noted that as temperatures rise, so do infestations of pests that eat away at trees. Dead trees are great fuel for fires.

“Scientists have predicted — and observed — the formation of more frequent, intense storms as a result of a warmer climate. That means two things: One, more frequent thunderstorms and lightning strikes that can naturally ignite wildfires; and two, flashier rainstorms that result in bursts of rain running off in streams, rather than soaking into the ground and substantially irrigating the landscape.

The caveat: A new study predicts that changes in the distribution of vegetation under a changing climate will have more to do with fire risk than the changing climate itself: So if the right plants colonize the West (eventually), they could offset the increased fire risk created by global warming.”

Federal stimulus money is starting to arrive in places such as Colorado. The money will go toward ecosystem-improvement and fuels-reduction projects.

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