Warming Climate Making Boreal Forests' Wildfire Season Longer, More Destructive

May 5, 2017

Warming increases fire danger in the far north …


A year ago, more than a thousand Canadian firefighters were struggling with a monster of a wildfire that burned nearly a million-and-a-half acres in northern Alberta and Saskatchewan.

Warm, dry conditions throughout the far north enabled the Fort McMurray Fire to spread rapidly, forcing the evacuation of the Alberta city for which it is named on May 3, 2016. It eventually burned about 90,000 acres in northern Alberta and Saskatchewan.
Credit Jonathen Hayward/The Canadian Press

By the time they finally snuffed the Fort McMurray Fire, it had killed two people and forced the evacuation of about 90,000 caused some $3.7 billion in damage –  “making it the largest such insurance loss due to a natural disaster in Canadian history,”says Randi Jandt, a fire ecologist with the University of Alaska Fairbanks.

Experts like Jandt say steadily warming temperatures in the far north make more such superfires possible in the region’s boreal forests.

“It illustrates the kind of fire behavior we can get under warmer conditions,” she said in a recent webinar. Decades of increasing temperatures in Alaska have lengthened the fire season and dried out vegetation, especially in the forest floor, and created conditions for busier fire season with bigger and more frequent wildfires, she added.

Since 1949, average temperatures in Alaska have risen by about a half-degree per decade.
Credit NOAA

“Three of the four warmest years ever were in the last three years, with 2016 by far and away the warmest year in Alaska,” she said.

Jandt says since 1949, average temperatures in Alaska have risen by about a half-degree per decade, and that’s made the growing season longer by about 2-and-a-half days per decade. She says a UAF study shows the number of extremely warm days, with an average 24-hour temperature of at least 70 degrees, have increased in recent years – a trend that’s expected to continue.

Alaska Fire Science Consortium fire ecologist Randi Jandt examines the effects of fire on tundra one year after the 2007 Anaktuvuk River fire in northern Alaska.
Credit Randi Jandt

“They’re expected to double by midcentury,” she said, “and double again by the last decade of the century.”

Jandt says another recent study shows the warmer temperatures and higher fire danger they bring are likely to double the number of wildfires in Alaska statewide – quadruple in some areas – partly due to more lightning strikes that warmer weather will bring. According to yet another study she cited, the average Alaska wildfire in the coming decades will be about 2-and-a-half times bigger than today.

Editor's note: Jandt's presentation was part of an April 18 presentation by the Alaska Fire Science Consortium.