After several years of relatively benign fire seasons, the West is headed into a hot, dry summer of potentially ferocious blazes like the ones that have scorched Colorado in recent weeks.
The wildfires that have already destroyed more than 700 homes and outbuildings along Colorado's Front Range and blackened hundreds of thousands of acres of New Mexico wilderness are not likely to be the season's last for one simple reason: drought.
"This year, fires are going big," Tom Harbour, fire and aviation director for the U.S. Forest Service, said last week. "We've had some really extraordinary runs … fires that are running 10 miles in lighter fuels. Fires that are running miles in forested areas."
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A dry La Nina winter and a paltry, quick-melting snowpack in much of the West have set the stage for another incendiary summer, compounding the effects of a long-term drought that has gripped the seven-state Colorado River basin for more than a decade.
"The reason Colorado is burning is they've had prolonged drought," said Bob Keane, a Forest Service research ecologist based in Montana. Add the high temperatures and gusting winds that hit the state last week, and you have a recipe for combustion.
Southern California is not immune. Officials are bracing for a higher fire danger after several years of respite from the catastrophic blazes that erupted over the last decade, including the 2009 Station fire, the largest in Los Angeles County history. Last winter, rainfall was well below average, leaving hills brown and dry even before summer began.
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Still, federal officials do not expect this year to be as disastrous as 2002, when massive blazes exploded all around the West, including Colorado's largest ever, the 138,000-acre Hayman fire. Wetter conditions in the Pacific Northwest and parts of the northern Rocky Mountains should help ease the fire threat there.
Drought, rising temperatures, a century of fire suppression policies that allowed many forested areas to grow unnaturally thick with fuel, and more and more people living on the wilderness edge have thrust the West into this new era of bigger and fiercer burns. The amount of land charred every year has soared compared with previous decades.
Since 2000, it has not been uncommon for wildfire seasons to end with a tally of 7 million to 9 million blackened acres nationally. Though total burned acreage dropped during a few years of milder weather, it spiraled again last year when flames galloped across parched Texas.
Researchers predict that rising temperatures associated with climate change will lead to more wildfires in much of the West. But it is hard to tease out the effects of global warming from natural climate cycles, which in past centuries have seized the region with long, severe droughts.
"We've had conditions like this in the past," Keane said. "So you can't say with any degree of certainty … that this is climate change. But what you can say is that it certainly meets the model of climate change."
As of Sunday, seven large fires in Colorado had charred a total of nearly 152,000 acres. None individually is as big as the Hayman was. But the Waldo Canyon fire west of Colorado Springs, which claimed two lives, and the High Park blaze in the mountains west of Fort Collins, now 100% contained, burned more than 700 structures, making them the most destructive in the state's history.
Colorado recognized the potential for a fiery summer, but "I don't think anyone was prepared" for what has occurred, said Chad Hoffman, co-director of the Western Forest Fire Research Center at Colorado State University at Fort Collins. Smoke from the High Park fire about 13 miles away shrouded the campus early last week and flames were visible on the horizon.
The Colorado blazes have raced across grass, shrub lands and timber, including ponderosa pine stands that are denser than they were historically. "There's a lot more fuel than there used to be," Hoffman said.
There are also a lot more houses. Though Harbour said Colorado had up-to-date fire prevention standards for new homes, older residences were not built with wildfires in mind, a situation throughout the West.
And whipping wind, triple-digit temperatures and dried-out fuel can make an inferno unstoppable until the weather changes. Rain came to the aid of firefighters in the High Park blaze, while cooler weather and rising humidity helped to calm the flames in Waldo Canyon, where the fire is now 45% contained.
All told, more than 1,500 structures have been lost to Western wildfires this season, including nearly 300 in Utah, 223 in Montana's Dahl fire and 254 in the Little Bear fire in New Mexico.
Far larger than the Colorado fires, the still-smoldering Whitewater-Baldy Complex fire in New Mexico destroyed only 20 structures because it has burned mostly in remote national forest lands, including the Gila Wilderness.
The Gila National Forest has also been a pioneer in using fire as a management tool, monitoring wildfires rather than rushing to put them out and using controlled burns to clean out younger, dense growth. An initial review of burn damage by the Forest Service suggests that approach has helped. Of the nearly 300,000 acres within the Whitewater-Baldy fire perimeter, slightly more than half burned lightly or not at all.
Prescribed fire and mechanical thinning of dense growth are crucial to making forest lands less vulnerable, Harbour said.
"It's that combination of having communities become fire adapted and improving the condition of the forest that is going to get us out of this death spiral of increasingly severe fire that we're in right now," he said.