Hotter Years, More Fires
The 2016 wildfire season has barely begun and dozens of large wildfires have already raged through Western states, with hundreds of thousands of acres burned. This comes on the heels of a 2015 wildfire season that was the worst on record in the U.S., with more than 10 million acres burned.
This intense activity is indicative of a growing trend in Western wildfires linked to changes in the climate. Spring and summer temperatures have been rising across the West, and mountain snowpack has been melting earlier. Taken together, these changes are creating more days where forests and grasslands are dried out and ready to burn.
To understand wildfire trends, we analyzed 45 years of U.S. Forest Service records of large wildfires (those fires burning more than 1,000 acres) from the western U.S. in our new report, Western Wildfires: A Fiery Future. We found that the average number of large wildfires burning each year and the total area burning in these fires have both increased dramatically since the 1970s.
More fires are burning across the U.S.
There are now three times more large wildfires burning across the West each year than in the 1970s. The annual area burned in these wildfires has increased six-fold. And wildfire season is now an average of 105 days longer than it was in the 1970s. During this time, the years with the hottest spring and summer temperatures were typically the years with the most large wildfires.
More acres are burning across the U.S.
The conditions that foster wildfires are likely to get worse in the next several decades. Projections based on 29 climate models suggest that the number of high wildfire potential days each year could increase by nearly 50 percent by 2050 if greenhouse gas emissions continue unabated. Southwestern states — including Arizona, California, New Mexico, and Utah — are expected to see the largest increases in high wildfire potential days by 2050.