Think modern wildfires are bad? Fires once burned up to 36 times more of the West, study says

Think modern wildfires are bad? Fires once burned up to 36 times more of the West, study says

30 October 2018

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USA – Wildfires tearing through the Western U.S. in recent years have burned whole communities to the ground, claimed countless lives and busted government firefighting budgets.

The destruction looks and feels unprecedented — and compared to the last several decades, today’s fires are extremely destructive and expansive, according to satellite data and other measures cited by Utah State University researchers.

But in a new study published by the American Geophysical Union journal Earth’s Future, those researchers argue that Western blazes today (even if they’re bigger than in the 1980s) are still consuming “a small fraction” of the land fires consumed before European settlers arrived en masse in the West.

“Wildfire area in the pre-settlement western U.S. was many times greater than the supposed ‘record highs’ of today,” the study said.

Researchers compiled long-term data on wildfires in the West to complete the study, and found that by the mid-20th Century as little as 500,000 hectares burned yearly in Western ecosystems. Compare that with the 7 million to 18 million hectares that burned each year before modern fire suppression began in the area — meaning as much as 36 times more land area burned in the West annually before the 1920s, according to researchers.

“Specifically, these records show that historically 4 to 12 percent of the entire western U.S. would burn each year,” Brendan Murphy, postdoctoral fellow in watershed science at Utah State University and the study’s lead author, said in a statement.

So while headlines often suggest the West’s blazes today are “unprecedented,” that’s only compared to data that was relatively recently collected, the study found.

That’s not to say wildfires haven’t inflicted unprecedented damage: Researchers note that more and more people live in the West. And they’re in areas that couldn’t have supported such high populations without modern water management.

But why did the number of acres burned fall so precipitously by the mid-20th Century?

Researchers said it was a combination of livestock eating up the plant material that fuels fires, the expansion of firefighting infrastructure like water towers and forest roads, new technologies like fire retardant and successful campaigns like Smokey Bear.

Now, however, fuel that’s built up from years of suppression is conspiring with climate change to increase the number of acres that burn again, researchers said.

Researchers said it’s important to point out the West’s fiery past because it highlights that wildfires are “an inevitable part of the future in the western U.S.,” and not simply a modern anomaly exacerbated by climate change.

“The notion of near complete fire suppression is unrealistic,” the study said. “Understanding the historical magnitudes and accepting the future potential of wildfire in this landscape is pivotal if we hope to change human behaviors, ensure the implementation of realistic solutions, and find a way to coexist with fire.”

Murphy said the research also shows that many are underestimating the risk wildfire poses to water supplies in the West.

Fires have big implications for water in the region because “high severity wildfires can cause significant erosion and deliver substantial amounts of sediment to rivers,” hurting quality and storage capacity, the study said.

“If we hope to better predict the future risks wildfires pose to water resources and more effectively manage our ecosystems, then it is critical we give other wildfire attributes, specifically burn severity, more consideration,” Murphy said.

Researchers said part of the solution should be increasing the amount of land subject to “managed wildfire,” so potential fire fuel can be burned off in controlled, low-risk conditions.

The study was funded by the National Science Foundation and the Utah Agricultural Experiment Station, the researchers wrote.

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