PerspectiveCalifornia’s Wildfires Are 500 Percent Larger Due to Climate Change

Published 17 July 2019

Californians may feel like they’re enduring an epidemic of fire. The past decade has seen half of the state’s 10 largest wildfires and seven of its 10 most destructive fires, including last year’s Camp Fire, the state’s deadliest wildfire ever. A new study finds that the state’s fire outbreak is real—and that it’s being driven by climate change. Since 1972, California’s annual burned area has increased more than fivefold, a trend clearly attributable to the warming climate. “Each degree of warming causes way more fire than the previous degree of warming did. And that’s a really big deal,” Park Williams, a climate scientist at Columbia University and an author of the paper, said. Among the many ways climate change might be messing with the environment, extra heat is among the simplest and most obvious. “Heat is the most clear result of human-caused climate change,” Williams said.

Californians may feel like they’re enduring an epidemic of fire. The past decade has seen half of the state’s 10 largest wildfires and seven of its 10 most destructive fires, including last year’s Camp Fire, the state’s deadliest wildfire ever.

A new study, published this week in the journal Earth’s Future, finds that the state’s fire outbreak is real—and that it’s being driven by climate change. Since 1972, California’s annual burned area has increased more than fivefold, a trend clearly attributable to the warming climate, according to the paper.

Robinson Meyer writes in The Atlantic that the trend is dominated by fires like the Mendocino Complex Fire—huge blazes that start in the summer and feed mostly on timberland. Over the past five decades, these summertime forest fires have increased in size by roughly 800 percent. This effect is so large that it is driving the state’s overall increase in burned area.

“Each degree of warming causes way more fire than the previous degree of warming did. And that’s a really big deal,” Park Williams, a climate scientist at Columbia University and an author of the paper, told me. Every additional increment in heat in the environment speeds up evaporation, dries out soil, and parches trees and vegetation, turning them into ready fuel for a blaze. For that reason, Williams said, hot summers essentially overpower anything else happening in Northern California. Even during a wet year, an intense heat wave can choke forests so that it is as though the rain never fell.

And it matters that heat is prompting this 800 percent explosion in forest fire—because among the many ways climate change might be messing with the environment, extra heat is among the simplest and most obvious. “Heat is the most clear result of human-caused climate change,” Williams said.