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The Donnie Creek wildfire burns in an area between Fort Nelson and Fort St. John, B.C. in this undated handout photo provided by the BC Wildfire Service.HO/The Canadian Press

British Columbia’s second-largest single wildfire in recorded history is rapidly gobbling up hundreds of thousands of hectares of forested land in the province’s northeast, but it’s not just the size of the burn that makes fire experts nervous, it’s the extreme temperatures inside of it.

Burning out of control through more than 500,000 hectares of boreal forest between Fort Nelson and Fort St. John, the Donnie Creek wildfire is being fed by dense fuel and dry conditions, both of which promise a hot blaze.

And that matters, says B.C. wildland fire ecologist Robert Gray. The higher the temperature a fire burns at, the more energy it releases and the more carbon it emits into the atmosphere. Werner Kurz, who leads the development of a National Forest Carbon Accounting System for Canada, says the Donnie Creek blaze has likely already let off over 77 million tons of carbon-dioxide-equivalent emissions, based on the Taiga Plains ecozone where it’s located and emissions averages from Natural Resources Canada.

Although wildfire scientists say a certain amount of burning is vital to reducing dangerous fuel loads and promoting regrowth, this extreme level of carbon release is unsustainable and increasingly a problem as climate change progresses and fire seasons intensify.

Mr. Gray describes the situation as a rapidly worsening feedback loop, wherein climate change creates hotter, dryer conditions, which spur more severe wildfire seasons, which in turn produce greater amounts of carbon, which then contribute right back into climate change.

The gravity of the issue is fairly new. For as far back as we know, forests have successfully self-regulated carbon emissions, with the amount released from wildfires balanced out by the plant life spurred in subsequent years. However, Canada’s forests haven’t absorbed as much as they’ve released for several decades now, according to the country’s annual greenhouse-gas (GHG) inventory reports. And wildfire emissions are a major contributor.

In 2021, the most recent year reported by Environment and Climate Change Canada, wildfires in the country’s managed forest areas (230 million hectares) produced 293 million tons of carbon dioxide and other greenhouse gases, together known as carbon-dioxide-equivalent emissions. The resulting release is equivalent to about 43 per cent of Canada’s GHG emissions from every other source that year.

The amount is striking, but isn’t a type of emission Canada has to include in its GHG reports to the United Nations. Despite being increasingly exacerbated by human activity, wildfires are still considered a natural disturbance and Canada chooses to keep them off the official record.

“It’s voodoo accounting,” Mr. Gray says. Regardless of how natural wildfire emissions are, he adds, their contribution to climate change is threatening.

And the trend of a net positive carbon release is likely here to stay if serious action isn’t taken, says Carolyn Smyth, a scientist at Natural Resources Canada and colleague of Mr. Gray and Dr. Kurz’s at the Pacific Institute For Climate Solutions.

Although the exact severity of this year’s wildfires isn’t yet known, the pace at which they’re burning is a strong indicator that 2023 could match or even surpass 2021′s carbon emissions, Dr. Smyth says. In just the last month, wildfires across Canada have already burned more land (about 5.4 million hectares) than was consumed throughout the entire wildfire season two years ago.

In 2021, B.C.’s fires accounted for 869,300 of the total 4.3 million hectares burned across Canada. In the province’s two worst seasons on record, 2017 and 2018, its wildfires made up about one third and one half of Canada’s burn area total, respectively. Alberta too has had some substantial fires in recent years. The Fort McMurray wildfire contributed to 611,466 hectares of Albertan land burned in 2016 (44 per cent of Canada’s total), and in 2019, an even greater 883,411 hectares were devoured (48 per cent of Canada’s total).

And contributing to climate change isn’t the only concern when it comes to carbon.

Dr. Christopher Carlsten, a respiratory medicine professor at the University of British Columbia, says carbon particles released from wildfires are capable of carrying allergens and pollutants long distances and overwhelming defensive mechanisms in people’s lungs.

What all is being released from a forest fire and how it could impact humans isn’t completely known, he says, but there’s far more than wood smoke floating through the air.

“People think of forest fires as maybe a campfire with nice pieces of wood, but it’s a much more complex and more biologically-active environment when you’re talking about a true forest.” Different types of plant matter, organisms, fungi and soil could release all manners of things when burned, Dr. Carlsten says. If man-made structures are burning, the list of airborne dangers lengthens greatly.

In the short term, this impacts young and elderly people – and those with respiratory or heart-related diseases – the most, but Dr. Carlsten says everyone is at risk as wildfire seasons intensify.

“We’re all susceptible, because if we’re going to be exposed for as long as we appear to be now, then people who are generally healthy are at risk for developing a disease.”

Dr. Carlsten and his colleagues at the Air Pollution Exposure Laboratory are so concerned about what is to come that, after almost 20 years of studying traffic pollution, they’re switching almost all of their focus to wildfires instead.

The most effective way of tackling the level of carbon released, according to Mr. Gray, is not by suppressing all fires (as has long been the strategy) but by reducing the amount of area being burned at a high temperature. Determining the best steps to do so is the goal of the Wildfire and Carbon project, which he, Dr. Kurz and Dr. Smyth work on together.

“Fire is a natural component of our ecosystems. We’re not going to be able to get rid of all fires. But we can reduce some of the fuels that are available to burn,” Dr. Smyth says.

Their team is looking to Indigenous stewardship practices for guidance and sees actions such as planting fire-tolerant species, creating more fire breaks in the landscape, removing fuels and restoring ecosystems following fires as promising.

“If extreme fires are going to become more common, we need to figure out ways to better live with fire, to be more resilient to fire,” Dr. Smyth says.

Editor’s note: A previous version of this article stated incorrectly the amount of carbon-dioxide-equivalent emissions removed by forests. This version has been updated.

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