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

Poetry contest started for Vancouver Island poets

“We’re such a unique group,” says founder on why she wanted to start the collective

North Island College ready for a virtual fall semester

“It’s a really good time to be a student.”

Ten hour planned power outage coming for north Island residents

To keep crews and the public safe, power must be switched off while BC Hydro completes the work.

A parent’s pandemic survival kit: Are you rewarding bad behaviour? Part 2

The phrase, “be good” is just an anxiety-provoking nebulous idea that threatens rejection.

All inquiry recommendations implemented after fatal Port Hardy RCMP shooting: Ministry

The Independent Investigations Office of B.C. cleared the RCMP officers involved of wrongdoing

B.C. records 146 new COVID-19 cases through long weekend

More that 28 people tested positive for the virus each day since Friday

Dinosaurs revived for animatronic auction in Langley

More than 500 robot dinosaurs, fossils, and exhibition gear are going on the block Aug. 6

B.C. paramedics responded to a record-breaking 2,700 overdose calls in July

Province pledges $10.5 million for expansion of overdose prevention response

Canada signs deals with Pfizer, Moderna to get doses of COVID-19 vaccines

Earlier in July both Pfizer and Moderna reported positive results from smaller trials

Canucks tame Minnesota Wild 4-3 to even NHL qualifying series

J.T. Miller leads Vancouver with goal and an assist

Cyclist in hospital after being hit by load of lumber hanging from truck on B.C. highway

A man is in hospital with broken ribs, punctured lung and a broken clavicle and scapula

COVID-19 vaccine efforts provide hope but no silver bullet to stop pandemic: Tam

There are more than two dozen vaccines for COVID-19 in clinical trials around the world

Two people die in propane heated outdoor shower near Princeton

Couple was attending a long weekend gathering

Most Read