Fire suppression is exacerbating wildfire severity in the US West: Study

Fire suppression activities are causing future blazes to burn at higher severity and under more hostile conditions — worsening the impacts of climate change, a new study has found.

Although suppression efforts minimize the overall area burned, they virtually eliminate the possibility for low- and moderate-intensity fires, according to the study, published Monday in Nature Communications. Fires in such environments become “biased” toward more extreme behavior, showing substantial increases in severity, the research found. 

“Fire suppression has unintended consequences,” lead author Mark Kreider, a Ph.D. candidate in the University of Montana’s forest and conservation sciences program, said in a statement.

“We’ve known for a long time that suppressing fires leads to fuel accumulation,” he continued. “Here, we show a separate counter-intuitive outcome.”

Kreider and his colleagues relied on computer simulations that accounted for the fundamental elements of fire: weather, fuel moisture, ignitions, fire growth, fire suppression and ecological effects. To isolate the impacts of suppression, they simulated thousands of blazes with identical biophysical conditions that differed only in the magnitude of suppression activities.

Ultimately, they were able to demonstrate that hypothetical attempts to suppress all wildfires would engender blazes so furious that their destructive effects would outpace those of both fuel accumulation and climate change.

This so-called “suppression bias,” Kreider explained, may therefore be exerting “a significant and underappreciated influence on patterns of fire globally.”

The simulated suppression activities caused areas to burn three to five times faster over a 240-year period in the U.S. West, relative to a world with no such action. Suppression also increased fire severity by an amount equivalent to a century of climate change or fuel accumulation, according to the study.

Traditional suppression works by removing lower severity blazes “that help perpetuate healthy forests” by burning thin-barked tree species,” senior author Andrew Larson, a professor of forest ecology at the University of Montana, said in a statement.

“I wonder how much we are altering natural selection with fire suppression by exposing plants and animals to relatively less low-severity fire and relatively more high-severity fire,” Larson questioned.

The authors compared wildfire suppression to the “over-prescription of antibiotics,” explaining that attempting to eliminate all fires only results in the eradication of the less intense fires.

But the scientists also offered some hope for a way out of these circumstances: Allowing more low- and moderate-intensity fires, they explained, could reduce or reverse the damage done thus far.

Enabling blazes to burn under moderate weather conditions while still suppressing those that occur during more dangerous fire weather could decrease average fire severity, according to the study.

“Part of addressing our nation’s fire crisis is learning how to accept more fires burning when safely possible,” co-author Philip Higuera, a University of Montana professor of fire ecology, said in a statement. “That’s as important as fuels reduction and addressing global warming.”

Going forward, the researchers emphasized the importance of developing and implementing technologies and tactics for safely managing wildfires during moderate burning conditions.

“By attempting to suppress all fires, we are bringing a more severe future to the present,” Kreider said.