On a hot July evening last year, a rancher tried to use a hammer and stake to plug a wasp’s nest. The hammer slipped, a spark flew, and a patch of dry grass ignited, according to the Los Angeles Times. Within minutes, the brush fire fed on bone-dry conditions and became too big to control.
It soon merged with another blaze and became the Mendocino Complex Fire, the largest wildfire in California’s history. It burned almost half a million acres, or roughly 720 square miles, before it was finally extinguished four months later. It killed one firefighter and injured four.
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.
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.