Nation must adapt to greater wildfire risk
Climate change means people must prepare for more fire danger, including – surprise – US East.
from the November 1, 2007 edition
Page 2 of 3
He and colleagues at the University of Arizona note that so far no research has identified a clear link between rising temperatures and wildfires in southern California's dry chaparral landscape. In a statement, the team notes that "the connection between global warming, Santa Ana winds, and extremely low southern California precipitation last winter are not known with sufficient certainty to conclusively link global warming with this disaster."
"We don't know how much the dice are getting loaded" in favor of such fire outbreaks in southern California, Dr. Westerling says in an interview. Computer models tend to agree that temperatures should warm, he says, but "they are all over the place" on changes in precipitation.
Yet global warming's fingerprints – earlier springs, earlier snowmelts, and warmer temperatures – have been appearing in other forested areas, he adds. In a study he and colleagues published in the journal Science in August 2006, the team found a sudden, marked increase in the number and lifetime of fires, as well as a longer fire season in the West generally – especially during the mid-1980s. These trends were particularly noticeable in forests in the northern Rockies at middle elevations. There, the interaction of people with the forest ecosystem – which can have its own powerful effect on fires – is far less pronounced than in other parts of the West.
Indeed, model projections point to similar trends in Canada and Russia's immense reaches of high-latitude forests, according to a research by a team led by Amber Soja, a researcher at the National Aeronautics and Space Administration's Langley Research Center in Hampton, Va.
That global warming might bring a greater fire risk to the already arid Western US might seem obvious. But the big surprise in the future may come farther east, says Ronald Neilson, a bioclimatologist at the US Forest Service's Pacific Northwest Research Station in Portland, Ore. It's in the east and southeast where global-warming-related wildfire risks will grow the most dramatically, his research suggests, even though the western US remains the country's wildfire hot spot.
Two out of 5 US homes are on the front lines
Why? As temperatures warm, the growing season will get longer. Woodlands will grow faster – at least for a few decades – fertilized by more atmospheric CO2. But annual precipitation amounts are expected to remain relatively constant.
Today, forests usually dry out just as the trees are going dormant for winter. In the future, however, eastern forests may dry long before the trees have a chance to shut down. Combined with bark beetle infestations (themselves a product of warming temperatures; they have occurred in the southern and western US and recently moved east), an increasing number of eastern woodlands could become prime wildfire fuel.
On a related front, two years ago, a team led by Volker Radeloff, a forest ecologist at the University of Wisconsin at Madison, pulled together the first national assessment of the collision between development and wild lands. The effort was driven by increased concerns about wildfire risks, Dr. Radeloff says.
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