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A warming climate will fuel larger, more frequent wildfires in the Sierra Nevada and other parts of the West, and the fires will contribute to climate change, according to a new study.
More than 20 international scientists, in the report published in the journal Science, said fire is not only a consequence of climate change but an important cause.
“Fire also influences the climate system. This is what we call a feedback,” Jennifer Balch, a fire expert at the University of California, Santa Barbara, told the Reno Gazette-Journal.
Scientists determined intentional deforestation fires, many set in tropical areas to expand agriculture or ranching, contribute up to a fifth of the human-caused increase in emissions of carbon dioxide, a heat-trapping gas helping to boost global temperatures.
The researchers called on the Intergovernmental Panel on Climate Change to fully integrate fire into its ongoing assessment of climate change.
Fire-climate feedbacks, they said, have been largely absent from global climate models.
“Extraordinary (fires are) occurring like a rash all over the planet,” said David Bowman, a forestry and wildlife expert at the University of Tasmania.
Fire of unprecedented ferocity swept across parts of Australia in February, killing about 200 people.
Similar fire activity can be expected elsewhere as the climate warms, including in the Sierra, where a 2007 blaze at Lake Tahoe destroyed 254 homes, scientists said.
“We are witnessing an increasing amount of so-called megafires,” said Thomas Swetnam, an expert on fire history and forest ecology at the University of Arizona. “Unfortunately, I think we are going to see more large fires in the western United States. The western United States is in a bull’s-eye.”
Swetnam was involved in a 2006 study that indicated increased fire activity is associated with increasing spring and autumn temperatures and an earlier spring snowmelt in western mountains.
That study found that wildfire frequency spiked to nearly four times the average experienced from 1970 to 1986, with the area burned more than six times previous levels.
The average length of the fire season increased by 78 days between 1987 and 2003 compared with 1970 to 1986, with fires starting earlier and burning later into the season.