Wildfire season is lasting longer, burning different | CAS in the Media

The number of acres burned so far in Washington’s wildfire season this year is on trend with what ecologists predicted. But the damage has been catastrophic, and it could be weeks before fire danger subsides. Dryer, hotter summers and changes to the state’s vegetation mean the fire season spans longer than it once did.

In the 20th century, fire suppression and exclusion in the American West by European colonizers prevented a lot of fires that would have otherwise naturally occurred.

“If you look at historic averages in the West, we don’t match the acreage of fire that would touch the West precolonization,” said Mark Swanson, a fire ecology professor at Washington State University.

Nowadays, where fires ignite, they tend to burn in ecosystems where fire was excluded for much of the 20th century. A buildup of grown vegetation as a result means those fires will likely burn at a higher intensity and severity — intensity being heat release and severity being what the flames do to the vegetation.

“We deliberately excluded fire, or suppressed it, for much of the 20th century in the West in the belief that fire was bad,” Swanson said. “The irony is that it allowed fuel to accumulate.”