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For decades the primary U.S. strategy to limit risks to people from wildfires has been to thin heavily wooded areas and eliminate buildup of dead trees so that when a fire inevitably erupts, it does not grow inordinately large and out of control. U.S. wildfire policy has centered on how far to take these steps. States and municipalities act on the policy by deciding whether to let small, natural fires burn rather than try to put them out, and whether to use “prescribed burns”—fires deliberately set and monitored to consume excessive “fuel” (those dead trees) in forests.
The strategy is misguided, however, according to a new paper published today in Nature (Scientific American is part of Nature Publishing Group).
“The fuel-accumulation focus is important in a certain set of forests, but in lots of places it’s inappropriate,” says Max Moritz, a specialist in wildfire and environmental science, policy and management at the University of California, Berkeley, and lead author of the paper. Recent big fires in southern California, for example, have been in shrubland, the predominant ecosystem in the region, not forests. Large fires in Texas (and Australia, for that matter) are occurring mainly in grasslands, not forests. Climate change is also a factor: areas that are drying are more prone to fires, whether they are home to trees or not. “And yet the debate and the solutions have been the same for a while,” Moritz says.
The main reason to fight wildfires is to prevent human deaths and the destruction of property—and the main factor creating that risk is where people choose to build, according to Moritz. Increasingly people are putting homes and businesses in places where the risk of fire is great or the chance for escape is small. The real issue, whether the surrounding environment is forest, shrubland or grassland, “is where and how we’ve built,” Moritz says. The best solution, he says, is to “better manage the wildland-urban interface.”
Even that interface is subject to some misconceptions. In most places worldwide, people are not building deep into a classic coniferous forest, so fuel reduction does not really help and takes the spotlight off other measures that can, Moritz says.
For example, the simple act of clearing vegetation far away from a house in a fire-prone area can help prevent the house from burning and also give firefighters a place to work from. Since houses often catch fire from blown embers, they should not have wood shingles on the roof. Even then, many houses burn because embers fly through attic vents and the houses ignite from the inside. “Existing houses should replace vents with ember-proof vents, and new houses should be built with the same,” Moritz says.
Municipalities should also start to refuse to allow people to build in highly fire-prone places, even though the individuals may think they have a right to build because they own the land, according to Moritz. Insurance companies should back this up by refusing to insure homes in those areas.
Help with better management and regulations will come as fire experts make better fire-hazard maps. “We’re getting close to the level of detail in flood-plain maps,” Moritz says. The last big step is to program winds into the models that generate the maps, to make them as accurate as possible. Once that is done, he says, “Then we can say, ‘Hey, municipalities, you should adjust your land-use plans accordingly.’ They already do it with floods and earthquakes.”
More funding would speed that process. “Lots of money goes to the fuel side of the issue,” Moritz says, “but why not have a lot of it go to retrofitting and reducing the vulnerabilities? We could be a lot smarter about fire.”