Exactly 30 years ago this year, NASA climate scientist James Hansen testified before Congress that Earth’s temperature was rising and humans were to blame.
It was the first time the issue of climate change became widespread public knowledge. Scientific predictions about the changes to come have borne out over the last three decades, including more intense wildfire seasons. However, a warming climate is just part of what is fueling the megafires and smoke-filled August skies people in the western U.S. are coming to expect.
“People talk about it as this is the new normal. I don’t think that’s necessarily the way to talk about it but we’re certainly loading the dice for more summers that are warm and dry and increasing the fire activity in our forests,” said John Abatzoglou, an associate professor of geography at the University of Idaho.
The ideal conditions for fire
The ingredients for a forest fire are the same as for a campfire, Abatzoglou said. “You’ve got your logs and sticks, you need enough fuel, and it needs to be dry. Then you need an emission source.”
In forest systems, the thing that limits fires from occurring is that the fuels or vegetation are not dry enough, Abatzoglou said.
“We have seen more and more summers over the past half century that have been warmer, and we have seen warmer summers globally. We’ve also seen a trend toward drier summers as well, regionally. Put those things together, and you have ingredients for fire.”
That’s not to say that every summer will be hot and dry. Conditions vary year to year, and some summers will be wetter, he said. “A lot of this tendency and trend we see is consistent and is what we expect to see more often, but not every year, in a changing climate.”
How fire became a villain in the U.S.
The other major factor behind larger and more intense wildfires is the fact that humans have been suppressing forest fires, a natural part of the ecological cycle, since the early 1900s. The Great Fire of 1910 shaped present day forest management practices. That year, a series of fires burned in Montana, Idaho and Washington. On Aug. 20 hurricane-force winds fanned flames throughout the Northern Rockies.The fires killed at least 85 people and destroyed entire communities. The smoke travelled to New England. In the aftermath, the Forest Service, founded five years before, established a policy to suppress fires before they could spread. Smokey Bear became its face. While the agency has eased this policy somewhat in the uninhabited backcountry, it has led to a build-up of fuels in many areas.
“Fire isn’t necessarily bad, even though we villainize it,” said Abatzoglou. “We can’t just log the forests, that’s not going to happen, but there are lots of policy bandaids we can implement.”
Among these are managing lands with more prescribed burning in seasons when fire danger is low, mechanical thinning and logging done in a way that reduces fire risk but doesn’t destroy the ecological resources the area provides, he said.
Breathing under a blanket of smoke
You don’t have to have your home or favorite hiking spot destroyed by fire to be affected by wildfire. Smoke that blanketed the region earlier this week came from fires burning in British Columbia, Canada. Last year, British Columbia had its biggest fire season on record, Abatzoglou said. This year is shaping up to be in the top three or four.
The research group Climate Central recently released a report that shows air quality in the U.S. has improved over the past 40 years through regulatory actions but it has declined in one area, the Northwest during the summer months.
“There’s a big bull’s eye over Idaho,” Abatzoglou said of the epicenter of poor air quality in the graphic.
How this will affect people’s long term health is still being studied, he said.
One thing that is different about the west than other parts of the country is the elevation differences between mountains and valleys, said Ed Marugg, environmental health director for Public Health-Idaho North Central District in Lewiston.
“A lot of communities are in the valleys. We see wildfire smoke settle in the valley. It sets up a recipe for bad air quality for the community we live in,” Marugg said.
What the future holds
While models predict increasingly warmer, drier summers, there are some wild cards in the mix that will affect the intensity of future fire seasons, Abatzoglou said.
First, there’s been a trend toward less precipitation in the region.
“The magnitude in decline in precipitation exceeds what the models project. It’s worse,” Abatzoglou said. “It’s beyond what we expect. There’s probably some natural variability that happens to coincide with the climate changes.”
While summers are getting hotter, winter hasn’t changed much in the region, Abatzoglou said.
Efforts also can be made to reduce fires started by humans, which usually begin at lower elevations. However, we can’t control lightning which typically starts fires at higher elevations.
“There’s certainly interesting questions about whether lightning will change in the future, whether we’ll see more or less,” Abatzoglou said.
Wildfires are a complicated problem, Abatzoglou said.
“It’s climate and it’s humans and it’s not going away, but we want to try to find a way to live with it.”