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

Provincial COVID-19 data can now be used for B.C. to prepare for a second wave

In the past week, B.C. has seen a slight spike in daily test-positive case counts

VIA Rail lays off 1,000 unionized workers across the country

Northern B.C. route Jasper to Prince George to Prince Rupert is not affected by VIA Rail layoffs

Sunflower Highway, art initiative to connect Fraser Valley, Thompson-Nicola and Okanagan

Sunflowers made out of reclaimed materials will be installed on public art trails

Residents warned to stay away from flooded Cache Creek park

Water might look shallow, but is several feet deep in places

Ashcroft receives grants to get new hot tub and lift station

‘The hot tub is a major benefit for many residents’

Islanders want BC Ferries to follow order that lets residents board before tourists

For ferry-dependent communities, ferries are often the sole practical lifeline to work, school or medical appointments.

Beverly Hills 90210 star’s family selling Vancouver Island Beach Resort

You can own Jason Priestley’s Terrace Beach Resort in Ucluelet for less than $5 million

COVID-19 cases identified in Kelowna, after public gatherings

Those who were downtown or at the waterfront from June 25 to July 6 maybe have been exposed to COVID-19.

Genetic detectives begin work to trace spread of COVID-19 in Canada

The kinds of genetic technology being used for this project did not exist when SARS hit Canada in 2003

Sports fishers protest Fraser River Chinook closures

Public Fishery Alliance wants hatchery fish open for harvest

Amber Alert for two Quebec girls cancelled after bodies found

Romy Carpentier, 6, Norah Carpentier, 11, and their father, Martin Carpentier, missing since Wednesday

B.C. man prepares to be first to receive double-hand transplant in Canada

After the surgery, transplant patients face a long recovery

Grocers appear before MPs to explain decision to cut pandemic pay

Executives from three of Canada’s largest grocery chains have defended their decision to end temporary wage increases

Most Read