As temperatures rise in the U.S. West, so do the flames.
The years with the most acres burned by wildfires have some of the hottest temperatures, an Associated Press analysis of fire and weather data found. As human-caused climate change has warmed the world during the past 35 years, the land consumed by flames has more than doubled.
Experts said the way global warming worsens wildfires comes down to the basic dynamics of fire. Fires need ignition, oxygen and fuel. And what’s really changed is fuel – the trees, brush and other plants that go up in flames.
“Hotter drier weather means our fuels are drier so it’s easier for fires to start and spread and burn more intensely,” said University of Alberta fire scientist Mike Flannigan.
It’s simple, he said: “The warmer it is, the more fire we see.”
The western summer so far is more than 3 degrees Fahrenheit (1.7 degrees Celsius) warmer than the 20th century average. California in July logged its hottest month in 124 years of record-keeping.
The five years with the most acres burned since 1983 averaged 63.4 degrees from April to September. That’s 1.2 degrees warmer than average and 2.4 degrees hotter than the years with the least acres burned, AP’s data analysis shows.
In California, the five years with the most acres burned (not including this year) average 2.1 degrees warmer than the five years with the least acres burned.
A degree or two may seem like not much, but for fuel it is crucial. The hotter it is, the more water evaporates from plants. When fuel dries faster, fires spread more and burn more intensely, experts said.