West poised for another big fire season
The upcoming fire season will be shaped over the next several weeks as temperatures warm and forests and grasslands begin to cure.
Storms provided ample but not extraordinary snow last winter. But in the age of climate change, that doesn’t always matter, according to a study by climate researchers at the University of Idaho, University of Colorado at Boulder and Columbia University.
In a paper titled “Switching on the Big Burn of 2017,” published in the journal Fire last week, researchers – including John Abatzoglou, associate professor at the UI Department of Geography, Jennifer Balch at the University of Colorado and others – the fire-taming conditions brought by big winters can be reversed by hot, dry summers.
They dissected the 2017 fire season, which burned nearly 10 million acres across the West and was responsible for nearly $3 billion in fire suppression costs and $18 billion in damages. The season was expected to be a mild one because of massive snowfall the previous winter.
However, the authors wrote that conditions aligned to “flip” what they call aridity, ignition and fuel “switches.” In short, the wet winter was followed by a warm, dry spring and a hot, dry summer. Grasses that grew tall from the winter moisture cured, and forests quickly dried as snow melted earlier than normal. The conditions align well with what climatologists expect to be a more frequent occurrence in the coming decades as the climate warms.
“Last year at this time all the forecasts regarding the fire season lookout were: ‘Yeah, it’s going to be pretty benign; we have a pretty big snowpack and that is going to buffer us from having a real active fire season, especially in the forest systems,’ ” said Abatzoglou. “That didn’t materialize. We had a really active fire season. Probably what was most notable was just the geographic expanse of the fire season.”
Though north central Idaho and southeastern Washington were not plagued by an unusual number of large fires, blazes did vex much of the West including parts of Montana, Oregon, California and British Columbia in Canada. The big fires inundated West Coast cities like Portland and Seattle with smoke. Fast-moving fires ripped first through California wine country and then through the foothills of Southern California.
In many places, the dry conditions and heavy fuel loads were sparked by human ignitions. According to the research, 89 percent of the fires were caused by people.
Climate change aided in flipping the switches. Last year was the fifth-warmest summer in the western U.S. since 1895.
Abatzoglou said those same switches are poised to be in play this summer. He said the abundant grasses that followed the winter of 2016-17 remain, and forests in the West are loaded with fuel, partly because of decades of fire suppression.
“All of these switches are going to be on again this year,” he said. “The level of how warm it was and how dry it was last summer – I’d be surprised if we see it that warm and dry in the summer this year, but odds are it will be a warm and dry summer. And odds are if that happens we will see another active fire season across the region.”
The researchers said the region needs to adopt policies that take increasing fire danger into account. That includes better planning of where homes are built. Dwellings close to or in forests make it more difficult to fight fires but also harder to treat fuels through prescribed burns or other treatments.
They also said education about fire and how to prevent human ignitions is needed, and fuel-reduction projects should be concentrated near rural communities.