Smoke can be seen rising from areas scarred by the Swan Lake Fire on Sunday, Oct. 6, 2019 at Mile 10 of Skilak Loop Road, on Alaska’s Kenai Peninsula. (Photo by Jeff Helminiak/Peninsula Clarion)

Smoke can be seen rising from areas scarred by the Swan Lake Fire on Sunday, Oct. 6, 2019 at Mile 10 of Skilak Loop Road, on Alaska’s Kenai Peninsula. (Photo by Jeff Helminiak/Peninsula Clarion)

Study finds scientific evidence of “zombie fires” in Alaska, Arctic

Zombie fires in boreal forests are associated with hot summers and deep burning into organic soil.

Climate change puts boreal forests at risk for “zombie” or holdover fires, which smolder after fire season and flare up the following spring. That’s according to a study published last month in the peer-reviewed journal Nature. The study was led by researchers at Vrije Universiteit Amsterdam in the Netherlands and co-authored by researchers at the University of Alaska Fairbanks and the U.S. Bureau of Land Management’s Alaska Fire Service.

Researchers studied boreal forests in Alaska and Canada, which are categorized by deep and organic soil, which is favorable for smoldering. Those conditions, exacerbated by climate change, may create “unusually favourable conditions for overwintering,” the abstract says.

Generally, researchers found that overwintering or zombie fires in boreal forests are associated with hot summers and deep burning into organic soil, which is becoming more common in recent decades in the geographies studied.

“Our results are based on an algorithm with which we detect overwintering fires in Alaska, USA, and the Northwest Territories, Canada, using field and remote sensing datasets,” the study abstract says. “Between 2002 and 2018, overwintering fires were responsible for 0.8 per cent of the total burned area; however, in one year this amounted to 38 per cent.”

Being able to predict overwintering fires, it says, could reduce carbon emissions and costs to firefighting costs if used by fire management agencies.

According to the study abstract, forest fires are generally viewed in the context of one fire season, however, some fires show “overwintering” behavior, meaning they continue to smolder beyond fire season and flare the next spring.

At least two zombie fires, or holdover fires, have been reported as the result of the 2019 Swan Lake Fire. That fire, which burned for almost four months on both sides of the Sterling Highway, burned more than 167,000 acres.

According to the Alaska Division of Forestry, the first holdover fire from the Swan Lake Fire was reported on June 15, 2020 near Milepost 66.5 of the Sterling Highway. That fire was a 10-by-10-foot hot spot that took firefighters about 10 minutes to extinguish.

The second holdover fire was reported a few weeks later near Milepost 68, in the Kenai National Wildlife Refuge. As of June 26, 2020, firefighters estimated that it was about 7.2 acres and not expected to grow in size. At least 20 firefighters responded to the fire, which rose from the Swan Lake Fire burn scar.

According to a UAF release, overwintering fires are still relatively rare and account for about 1% Alaska and Canada’s total burn area. However, temperatures in the Arctic are expected to increase more quickly than in other parts of the world, with early snowpack melts already being reported in Alaska.

The Alaska Division of Forestry encourages residents to adopt Firewise principles and to adhere to burn permits, which can be accessed on their website.

More information about the study can be found in Nature or on UAF’s website at news.uaf.edu.

Reach reporter Ashlyn O’Hara at ashlyn.ohara@peninsulaclarion.com.

More in News

The Alaska State Capitol is seen on Wednesday, April 6, 2022. (Peter Segall / Juneau Empire)
Legislature modernizes 40-year-old definition of consent in sexual assault cases

‘Alaska took a gargantuan step forward in updating our laws,’ says deputy attorney general

Project stakeholders cut a ribbon at the Nikiski Shelter of Hope on Friday, May 20, 2022, in Nikiski, Alaska. (Ashlyn O’Hara/Peninsula Clarion)
Stakeholders celebrate opening of Nikiski shelter

The shelter officially opened last December

Peter Segall / Juneau Empire
Gov. Mike Dunleavy speaks with reporters Thursday about the state’s budget at the Alaska State Capitol. Dunleavy said lawmakers had sent a complete budget, and that there was no need for a special session.
Dunleavy: No need for special session

Governor calls budget “complete”

A magnet promoting the Alaska Reads Act released sits atop a stack of Alaskan-authored and Alaska-centric books. Lawmakers passed the Alaska Reads Act on the last day of the legislative session, but several members of the House of Representatives were upset with the bill, and the way it was passed. (Ben Hohenstatt / Juneau Empire)
In last-minute move, Legislature passes early reading overhaul

Rural lawmakers push back on Alaska Reads Act

Graduates wait to receive diplomas during Connections Homeschool’s commencement ceremony on Thursday, May 19, 2022, in Soldotna, Alaska. (Ashlyn O’Hara/Peninsula Clarion)
Connections honors more than 100 graduates

The home-school program held a ceremony Thursday in Soldotna

Alaska Senate President Peter Micciche, left, and Senate Minority Leader Tom Begich, right, meet with reporters in Micciche’s office in the early morning hours of Thursday, May 19, 2022, in Juneau, Alaska, after the Legislature ended its regular session. Micciche, a Republican, and Begich, a Democrat, discussed their working relationship, as well as well as parts of the session they were either pleased with or disappointed with. (AP Photo/Becky Bohrer)
After House balks at bigger figure, budget OK’d with $3,200 payout per Alaskan

Budget finishes as second-largest in state history by one measure, but Dunleavy could make cuts

Loren Reese, principal at Kenai Alternative High School, gives Oliver Larrow the Mr. Fix It award Wednesday, May 18, 2022, at Kenai Alternative High School in Kenai, Alaska. (Photo by Jeff Helminiak/Peninsula Clarion)
Kenai Alternative graduates 22, says goodbye to principal

The ceremony included special awards customized for students

Graduates throw their caps into the air at the end of Soldotna High School’s commencement ceremony on Wednesday, May 18, 2022, in Soldotna, Alaska. (Ashlyn O’Hara/Peninsula Clarion)
‘We never fell down’

Soldotna High School honors more than 100 graduates

Brandi Harbaugh gives a presentation during a joint work session on Tuesday, March 2, 2021, in Soldotna, Alaska. (Ashlyn O’Hara/Peninsula Clarion)
Mill rate decrease, max school funding included in proposed borough budget

The final document is subject to approval by the Kenai Peninsula Borough Assembly

Most Read