A new study says that since 1984, heightened temperatures and aridity have caused fires to spread across twice as much area as they would have otherwise.
Growing up in the foothills of Los Angeles’ San Gabriel Mountains, fires were just part of life. Some days we would wake up and the hills would just be a patchwork of raging flames and the cars would be covered in a layer of ash. But it never seemed as bad as it does now; I figured this was just a matter of adult versus child perspective.
But now a new study from Columbia University says that fires really are worse. And not only that, but that human-induced climate change is to blame. The researchers say that climate change is responsible for doubling the area affected by forest fires in the U.S. West since 1984. Thanks to heightened temperatures and the ensuing aridity, fires have reached across an additional 16,000 square miles than they otherwise would have. The authors warn of a bleak fire future in coming decades that will accompany further warming.
"No matter how hard we try, the fires are going to keep getting bigger, and the reason is really clear," said study coauthor Park Williams, a bioclimatologist at Columbia University's Lamont-Doherty Earth Observatory. "Climate is really running the show in terms of what burns. We should be getting ready for bigger fire years than those familiar to previous generations."
In the 1980s fires in the west took an abrupt leap in terms of area burned, the number of large fires, and length of the fire season. These troublesome increases have continued, and recently scientists and public officials have in part blamed human-influenced climate change. The researchers wanted to quantify the problem. "A lot of people are throwing around the words climate change and fire – specifically, last year fire chiefs and the governor of California started calling this the 'new normal,' " says lead author John Abatzoglou, a professor of geography at the University of Idaho. "We wanted to put some numbers on it."
The researchers looked at the overall fire increase since the 80s and used a complex set of models to determine how much of the increase was due to climate change and what was due to other factors, they say. The other factors include a long-term natural climate oscillation over the Pacific Ocean that has pushed storms away from the western part of the country. Another factor is in firefighting itself. “By constantly putting out fires, authorities have allowed areas they "saved" to build up more dry fuel, which later ignites, causing ever more catastrophic blazes,” says Abatzoglou. "We're seeing the consequence of very successful fire suppression, except now it's not that successful anymore."
Williams and Abatzoglou say the study doesn't take into consideration other factors that could be offshoots of climate warming, and so may be understating the effect. Things like millions of trees killed in recent years by beetles that thrive in warmer weather, and declines in spring soil moisture brought on by earlier snowmelt.
This summer saw tremendous fires – around 3 million acres burned across the country, mostly in the West and across to the Dakotas and down into Texas. Some experts predict that the fall could be even worse as it’s a time of dangerous conditions; desert winds meeting fuels that have been drying for many months.
Many scientists believe the expansion of western fires will persist for years. Eventually, Williams and others predict, so many western forests will burn that they will become too broken up for fires to spread easily. But, Williams says, "there's no hint we're even getting close to that yet. I'd expect increases to proceed exponentially for at least the next few decades." In the meantime, he says, "It means getting out of fire's way. I'd definitely be worried about living in a forested area with only one road in and one road out."
Read more about the research at Columbia University's Earth Institute website.