A helicopter dumps a load of water on the Philpot Road fire outside of Kelowna, B.C., Monday, August 28, 2017. New research suggests that bigger, hotter wildfires are turning Canada’s vast boreal forest into a net source of climate-changing greenhouse gases. THE CANADIAN PRESS/Jonathan Hayward

Hotter, larger fires turning Canada’s boreal forest into carbon source: research

With climate change, fires are becoming more frequent, larger and more intense

Bigger, hotter wildfires are turning Canada’s vast boreal forest into a significant new source of climate-changing greenhouse gases, scientists say.

The shift, which may have already happened, could force firefighters to change how they battle northern blazes, said Merritt Turetsky, an ecologist at the University of Guelph and co-author of a paper that appeared in the science journal Nature on Wednesday.

“It’s making it much more difficult for us to target those reductions in human emissions because, all of a sudden, we have all these unaccounted-for sources.”

The boreal forest, a band of green that stretches over six provinces and two territories, has long been a storehouse of carbon.

Although fires sweep through as often as every 70 years, much carbon remains in the soil and slowly builds up — up to 75 kilograms of carbon per cubic metre, some of it thousands of years old.

But with climate change, fires are becoming more frequent, larger and more intense.

Researchers from five U.S. and four Canadian universities wanted to see if that was affecting stored carbon. They looked at the impact of the 2014 fire season in the Northwest Territories, which burned the largest area on record.

“These were large and severe fires,” said Xanthe Walker of Northern Arizona University. “We thought this is when and where (stored carbon) would burn.”

The team found that even after the fires, older forests continued to preserve carbon where it was protected by a thick layer of organic soil.

But the old carbon burned in nearly half of the younger stands where the soil wasn’t as thick. And what didn’t burn rapidly decomposed into the atmosphere.

“There are areas where there’s no organic soil left and it’s just exposed mineral soil,” Walker said.

Turetsky said the boreal forest is gradually becoming younger as fires increase in size and frequency.

“Now those old forests are young forests, so when the next forest fire hits that area, those are going to be systems that are vulnerable to legacy carbon release.

“We can have thousands of years of productivity stored and then released in a matter of minutes.”

At some point, fires will release more carbon from the boreal forest than it’s able to store.

“I think we’re right on the tipping point now,” Turetsky said. “I think it’s happening in the western provinces already. I think it’s happening in Alaska.”

This summer has been an unprecedented fire season across the circumpolar North. There have been more than 100 major fires burning north of the Arctic Circle and in boreal forests in places such as Siberia.

“That soil structure is all the same,” Walker said. “Presumably, they all have legacy carbon.”

The amount of old carbon released is still small, especially relative to that released by fossil fuels. But it complicates the task of bringing overall carbon emissions under control. It could also complicate how forest managers approach fires.

Wildfires in remote areas are often simply left to burn. Turetsky said firefighters may have to rethink that to protect stands that store a lot of carbon.

“The Canadian Forest Service is starting to think about old carbon as a valuable resource.”

The role of Canada’s huge forested areas is beginning to change, she said.

“Our forests are no longer carbon sinks.”

ALSO READ: Brazil’s president claims NGOs could be setting Amazon fires

Bob Weber, The Canadian Press


Like us on Facebook and follow us on Twitter.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Province asks health-care staff to be ‘vigilant’ in screening for possible coronavirus cases

This comes after U.S. health officials confirmed a case of the virus in Washington State

Victoria man out $6,000 in latest gift card phone scam

Fraudsters claimed to be a member of a bank’s “fraud sting team”

Homes fit for royals for sale in North Saanich

Prince Harry and Meghan Markle have returned to Greater Victoria

Gold Rush star dons Lucky Lager shirt in latest episode

Brennan Ruault, originally from Invermere, joined the show in the sixth season

VIDEO: Protesters block entrance to Victoria government building to support Wet’suwet’en First Nation

Activists want Wet’suwet’en Hereditary Chiefs demands to be upheld, observed and respected

Boy, 13, arrested after alleged assault involving girl at B.C. middle school

Boy alleged to have used ‘inappropriate levels of force’ to injure the girl

B.C. player becomes only second Canadian to enter Hall of Fame of Baseball

Walker received 76.6 percent of the Baseball Writers of America Association vote

PHOTOS: Heavy snowfall breaks window, causing avalanche into B.C. newsroom office

It was a chaotic start to the week for the Kitimat Northern Sentinel

Canadian law firm launches class action on behalf of Iran flight victims

Flight 752 was shot down by Iran shortly after take off

Mission Hill cellarman fired after mistakenly dumping $162K of wine down the drain

The former employee filed a grievance with the West Kelowna winery but was unsuccesful

Police suspect foul play in Cowichan Tribes death

Police are looking at foul play in relation to a death on… Continue reading

Hospital patient pleads guilty to dumbbell assault of nurse in Abbotsford

Neale Heath admits to assault causing bodily harm in attack last September

Most Read