As the climate warms, forest fires in the West increasingly will feast on acres of dry brush, growing into giants. In a cycle that will become routine, homeowners will flee, while firefighters will rush toward their houses — and away from areas where they could be putting out wildfires.
Bigger, unwiedly burns — megafires — are becoming the new normal, according to a new report, which points to several reasons: States such as California are getting parched more frequently by drought; housing developments are pushing more deeply into forests; and the U.S. Forest Service is generally suppressing fires rather than letting them burn naturally, which would reduce the brush that fuels future fires.
“That’s one of our biggest conundrums,” said Scott L. Stephens, a professor of fire science at the University of California at Berkeley. “We continue building. We make fire management so much more difficult. The first thing you’re going to do is run and protect people’s homes.”
In 1993, the average cost of fighting wildfires was $350 million a season. Now, it’s $2 billion, said Stephens, the lead author of “Temperate and boreal forest mega-fires: characteristics and challenges,” published recently in the journal Frontiers in Ecology and the Environment.
“The cost is going up, and one reason is the extreme amount of resources that has to be put into putting out fires near an urban interface,” Stephens said. “Having those houses there . . . man, that gets expensive. A fire engine every four, five or six houses, and there are hundreds of houses out there.”
The review’s conclusions underscore what the agencies responsible for fighting wildfires — the Interior Department and the Agriculture Department’s Forest Service — have said for years.
Global warming is accelerating climate change in the West, resulting in winters with less precipitation and a drier landscape. The wildfire season that historically started in June and ended in September now starts in May and ends in September.
“We’ve had record fires in 10 states in the last decade, most of them in the West,” said Agriculture Department Undersecretary Harris Sherman, who oversaw the Forest Service as it battled a massive Colorado fire in 2012 before retiring last year.
It once was rare to see 5 million cumulative acres burn in a year. In recent seasons, the amount of acreage burned in wildfires has been twice that.
Areas where wildfires were recorded every 150 to 200 years — such as some regions of the Rocky Mountains and Yellowstone National Park — will be drier, stocked with fuel and highly vulnerable to megafires, Stephens said — “a strong area of change.”
California recorded its second- and third-largest wildfires in back-to-back years: the Rush Fire, which was started by lightning in 2012, and the Rim Fire, which was ignited by a camper’s illegal campfire last year, according to the California Department of Forestry and Fire Protection.
In 2013, the state had its driest year on record, and the land is primed for more fire. But the review argued that megafires are not defined by size but by their threat to life and property.
The Yarnell Hill Fire in Arizona last year fits that description, as 19 elite firefighters, Granite Mountain Hotshots, perished in a blaze that threatened the Model Creek subdivision and other communities there.
More and more humans living in fire-prone areas is a major problem, said the authors, a team of 11 scientists including Robert E. Keane of the Forest Service’s Rocky Mountain Research Station in Missoula, Mont., and Jan W. van Wagtendonk, of the U.S. Geological Survey’s Western Ecological Research Center in Yosemite National Park, Calif.
“In many instances, local bylaws and land-use planning policies fail to consider the risk of megafires and are inadequately enforced,” they wrote. “People are building and living in dangerous locations and are not taking adequate fire protection measures.”
Stephens said that firefighters in the West should increase the number of controlled burns to get rid of the fuel on which fires feed. He said states in the South, including Florida, Georgia and South Carolina, are more apt than those in the West to use that method to control fires and protect private land.
“If you look at the South, it has a lot of pine systems we have in the West, and they have a . . . prescribed burning on private land,” Stephens said. Residents in the South have a “much higher tolerance of smoke in the air,” he said. In the West, “you’ll have a long line of people complaining.”
“Why don’t we hear about all these houses burning down and people dying in the South?” Stephens said. “They’re doing a better job.”