The Perfect Firestorm
Welcome to the new era of "megafires," which rage with such intensity that no human force can put them out. Their main causes, climate change and fire suppression, are fueling a heated debate about how to stop them.
The question of what to do about megafires is a hot topic. The Fire Lab's Jack Cohen believes fervently that fires are inevitable and ecologically important, and that we should set more of them on purpose under the right conditions to lower the risk of uncontrollable future fires.
Mark A. Finney, a research forester at the lab, illustrates what that means in practice. In his office, he points to a poster-sized satellite image on the wall, titled "Rodeo-Chediski Fire: June 21, 2002." The infamous Arizona conflagration devoured 468,000 acres, and this photo shows the charred landscape stretching across many miles, with a few curious green patches. "The only places that are green," Finney says, circling the sections with a laser pointer beam, "are places where there had been prescribed burns."
Experts have also found ways to significantly cut property losses. An estimated eight million homes have been built in western U.S. fire zones since 1970, and the bulk of efforts go toward protecting homes and communities in fire-prone areas. Yet research at the Fire Lab and elsewhere shows that homes don't have to be lost just because the forest around them is. If houses are located 100 feet from combustible materials and are built with materials like asphalt roof shingles that resist the spark of flying embers, it's possible to save the structures even when the fires themselves are irrepressible. When it comes to most of these fires, Cohen says, "we do not have natural disasters; rather we have human disasters during natural disturbances."
In the wake of a series of massive burns in California, some of Cohen's findings are working their way into practice. Insurance companies are bumping their rates in fire zones, as they do in earthquake-prone areas. That may deter development, which is critical, says University of Colorado geographer Tania Schoennagel. She cites a study saying that only about 15 percent of the overlap between wild and urban areas has been turned into residential areas. But that total could grow significantly if we don't curtail it. "Control fire risk?" asks Schoennagel. "Control development in wildlands."
Some fire professionals advocate a bigger, faster, more efficient response: loading 747s with fire retardant, and dispatching fleets of DC-10s to bear down on spreading fires. Fire managers employ NASA satellites to figure out how fires will behave and spread, and thermal images beamed from space help them decide how to deploy resources. Weather satellites detect cold fronts moving in, which are almost always preceded by winds that can fan flames. Laser imaging helps determine distance and range as well. And advances like a fire-suppressant material made from frozen crystals of water and carbon dioxide bonded together may also prove useful in some cases. Yet despite all these tools, many fire science experts agree that when the biggest fires rage in the wrong conditions, no human force can put them out.
Clearly, enlisting more squadrons of tanker planes to drop ever-increasing amounts of retardant isn't going to work in the long run. Neither is letting every fire burn unchecked. There's a growing consensus that our way out of the hot woods will require a nimble approach to managing the landscape.
In addition to prescribed fires, experts increasingly agree that people can take more responsibility for living in flammable areas. Steven Pyne, a fire historian at Arizona State University and a prolific author on the subject, points out that Australia, for example, is "light years beyond us" in teaching communities how to protect their property by creating "defensible space" around homes--clearing trees and brush a certain radius around their structures. Changing laws to eliminate a mortgage tax deduction for second homes or charging developers the full cost of public services (like putting out rural fires) would go a long way. "Knowing that you might be called upon to protect your house should concentrate the mind wonderfully with regard to wood-shingle roofing, house-clinging shrubs, and firewood stacked under decks," says Pyne.
Ultimately, though, fire will do what it does, and humans will argue about how to respond. Cohen understands that when it comes to fire policy, philosophy plays as big a role as thermodynamics. His experiments illuminate physical properties of fire in a biological system, but it is in the realm of culture that the debate must play out. "The societal response to fire is about perceptions of personal and property protection," he says. "The scientific findings are about abstract ecological function and fire physics."
There's nothing abstract about a fire burning for weeks or months, choking the sky with smoke and subjecting wildlife, plants, and people to one of nature's most awesome forces. In the end, "the phenomenon of megafires can be attributed to one common cause--us," says Pyne. "Even global warming is apparently an outcome of our combustion habits." Fires, and big ones, are thus part of our flammable planet's very nature.