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

Lacombe Community Refugee Effort hopes to reunite more of the Al Omar family

Bashar Al Omar’s brother is currently living in Lebanon

Town of Blackfalds looking for input to reduce environmental impact

Infrastructure services asks for input on how the strategy will address environmental concerns

Ryon Holmedal brings Tethers to the Lacombe Performing Arts Centre

Tethers is multidisciplinary musical experience

Town of Blackfalds taking next step towards a new brand

Mayor Richard Poole wants everyone in the community to help shape the future direction of Blackfalds

WATCH: Night Among the Stars Celebrity Dance-off supports Lacombe BBBS

Over $12,000 raised for Dancer’s Edge Parents Association and Lacombe BBBS

VIDEO: Outpouring of worldwide support for bullied Australian boy

Australian actor Hugh Jackman said ‘you are stronger than you know, mate’

Trudeau: Time for blockades to end and Indigenous leaders to work with government

Prime minister says situation in Coastal GasLink pipeline dispute is ‘unacceptable and untenable’

Canadians released from coronavirus-ridden cruise ship in Japan fly home

Those who were cleared to travel are to be screened again at Canadian Forces Base Trenton

Study says flu vaccine protected most people during unusual influenza season

Test-negative method was pioneered by the BC Centre for Disease Control in 2004

Saskatchewan and B.C. reach championship round at Scotties

British Columbia’s Corryn Brown locked up the last berth in Pool B

Portrait of the Coastal GasLink, a pipeline to divide a nation

In mid-February, 46 per cent of the pipeline route had been cleared

Alberta ends master agreement with doctors, new rules to be in place April 1

The current master agreement with physicians ends March 31

Alberta rail conductor fired for social media posts awarded money, but not reinstatement

Arbitrator Richard Hornung says that he agreed with the Teamsters union

Most Read