Study: Climate Change Has Doubled Western U.S. Forest Fires

A new study says that human-induced climate change has doubled the area affected by forest fires in the U.S. West over the last 30 years.

Since 1984 heightened temperatures and resulting aridity have caused fires to spread across an additional 16,000 square miles than they otherwise would have — an area larger than the states of Massachusetts and Connecticut combined, according to the study.

The study appeared in the journal Proceedings of the National Academy of Sciences.

The authors warn that further warming will increase fire exponentially in coming decades.

“No matter how hard we try, the fires are going to keep getting bigger, and the reason is really clear,” study coauthor Park Williams, a bioclimatologist at Columbia University’s Lamont-Doherty Earth Observatory, said in a statement. “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.”

The study shows that fires in Western forests began increasing abruptly in the 1980s, as measured by area burned, the number of large fires, and length of the fire season.

Average temperatures in forested parts of the U.S. West have gone up about 2.5 degrees F since 1970, and are expected to keep rising, the study states.

The overall increase in fire since the 1980s is about twice what the researchers attribute to climate change, while the rest is due to other factors, the authors say.

One factor has been a long-term natural climate oscillation over the Pacific Ocean that has steered storms away from the Western U.S.

Another cause might be firefighting itself.

By constantly putting out fires, authorities have allowed areas they to build up more dry fuel, which later ignites, causing ever more catastrophic blazes, the researchers say.

“We’re seeing the consequence of very successful fire suppression, except now it’s not that successful anymore,” said Abatzoglou.

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