For more than 30 years, Werner Kurz has been studying forests and carbon, wrestling with questions such as how much carbon trees absorb as they grow and how much they emit as they die.
This year, he’s tracking a milestone: A season in which greenhouse gas emissions from wildfires in Canada are expected to exceed the combined emissions from all of Canada’s economic sectors – including oil and gas, agriculture and electricity generation – for what Dr. Kurz says would be a first in recorded history.
As of late July, Dr. Kurz estimated the carbon emissions from this year’s wildfires at about 1,420 megatonnes of CO2 equivalent. That compares with 670 megatonnes of CO2 equivalent from all economic sectors in Canada in 2021, the most recent year for which figures are available.
That milestone has added urgency to the question of how to manage Canadian forests.
In the past, forestry management focused on protecting timber, infrastructure and communities by emphasizing wildfire suppression. Now, with wildfires burning across the country – as of Aug. 1, 13 million hectares, an area nearly twice the size of New Brunswick, had burned – and associated emissions on the rise, there are calls to change forestry practices. The idea is not only to reduce wildfire risk, but to bolster other forest attributes, including their ability to help cool a warming planet.
Forests can act as a carbon sink when they absorb carbon through photosynthesis. But they can also release carbon as they decay or die as the result of old age, fire or disease. Canada’s forests – which account for about 9 per cent of the world’s total – are becoming a net source of emissions because of wildfires and insect outbreaks, according to an April report by Jerry DeMarco, Canada’s Commissioner of the Environment and Sustainable Development.
Changes designed to reverse, or at least mitigate, that trend would vary according to regional ecosystems, but could involve methods such as prescribed burns, replanting logged or burned areas with different species that are resistant to fire or better suited to warmer, dryer weather, and using wood waste to generate electricity.
How and when such changes are implemented has implications for future wildfire seasons, government budgets and Canada’s net-zero ambitions.
Canada has 362 million hectares of forest, with about 60 per cent classified – for greenhouse gas reporting purposes – as managed forest, and the rest classified as unmanaged. As allowed under international guidelines, Canada does not report wildfire emissions from unmanaged forests – northern areas where fires may be left to burn unless they threaten communities or infrastructure – because those emissions are deemed natural disturbances, not human-caused.
And while Canada does track and report emissions from wildfires on managed forest lands, it doesn’t include those emissions when adding up total emissions for the sector, focusing instead on human-related activities such as logging and tree-planting. (Wildfire emissions are included in the National GHG Inventory as an information item.)
That approach is designed to focus on human-caused emissions that can be modified by, for example, technology or government policy rather than natural disturbances such as wildfires and insect outbreaks that can vary wildly from year to year.
But the sheer magnitude of wildfire emissions is changing the calculus.
Dr. Kurz’s 1,420-megatonne estimate takes into account wildfires in both managed and unmanaged forests. On their own, wildfire emissions from managed forests, at a projected 660 megatonnes, are on track to match or exceed the 670 megatonnes generated in 2021 by all other sectors combined, including oil and gas, electricity and transportation.
By comparison, the relatively small area burned in Canada’s managed forests in 2020, a moderate year for wildfires, amounted to about 8.8 megatonnes, according to the 2022 version of The State of Canada’s Forests, an annual federal report.
That’s where forest management comes in.
In a recent paper, Dr. Kurz and colleagues looked at how salvage logging (harvesting fire-killed wood for lumber or other purposes) and replanting after wildfires in B.C. could reduce greenhouse gas emissions compared with a “do-nothing scenario” that relies on natural regeneration. They found modest benefits that would take at least 20 years to be realized, once emissions from harvesting and cleaning up debris were taken into account.
“Our results suggest that mitigation efforts might be better directed at reducing wildfire risks and emissions in the first place, rather than rehabilitating post-fire outcomes,” the paper states.
Such mitigation efforts could include prescribed burns, which refer to the planned, intentional use of fire in a specific area, sometimes to help control a wildfire. The term can cover planned burns of debris piles left over from logging as well as cultural burning, an Indigenous practice used to manage the landscape to, for example, boost berry crops or improve wildlife habitat.
Prescribed burns can help reduce dead trees, shrubs and underbrush that can become fuel for a wildfire. Several reports, including a review commissioned by the B.C. government in the wake of a devastating wildfire season in 2003, have flagged fuel buildup as a concern in the province.
A recent report by the B.C. Forest Practices Board said much of B.C. is in a “fire deficit” owing to human-caused wildfire suppression in areas where natural wildfires are necessary. A 2021 provincial threat analysis found 45 per cent of public land in the province is at high or extreme threat of wildfire.
Prescribed burns and fuel breaks – areas cleared of brush and trees to protect sites from burning – have been part of wildfire management since at least 1990 through FireSmart Canada, a program founded that year to focus on reducing wildfire risk in the wildland urban interface (WUI), where human activity meets forest areas. Since then, the program’s “seven disciplines” – including vegetation management – have become the framework for community wildfire plans across the country.
But such programs don’t do enough to tackle the fuel load on the broader landscape, according to the B.C. Forest Practices Board report, which said just over 1 per cent of the WUI in that province had been treated since 2018 – efforts that “do not come close to achieving the scale required to restore landscape resilience.”
Mike Flannigan, a wildfire expert at British Columbia’s Thompson Rivers University, is skeptical about the potential for prescribed burning to make a big difference to forest health, saying the practice doesn’t suit all ecosystems, is relatively expensive and comes with risks, including escapes (when planned burns jump beyond boundaries set out in a burn plan).
“The fuel load issue is valid for Ponderosa pine and interior Douglas fir, but it’s a very small percentage of our forests in B.C. and incredibly small per cent in Canada,” Dr. Flannigan said.
Rather than investing heavily in prescribed burns, he’d like to see authorities step up prevention and preparedness. That could mean making greater use of tools like backcountry bans in high-risk periods – such as the hot, dry weather in parts of Alberta this spring – to prevent human-caused fires.
Lightning is the main cause of Canadian wildfires, accounting for about 50 per cent of fires and 85 per cent of the area burned over the past 40 years, according to the Canadian National Fire Database. But human-caused fires, whether the result of campfires, careless smoking, overheated equipment or some other cause, account for a significant number of fires each year. The Alberta Wildfire Service, for example, links about half of the fires in that province so far this year to human causes.
Dr. Flannigan also favours lining up firefighting resources ahead of time when forecasts call for extreme fire conditions, even if those resources turn out not to be required.
Such an approach would mean shifting focus, and possibly funds, toward mitigation instead of response, something many in the forestry sector say is essential to improving forest health.
“We spend six or seven dollars on response costs for every one dollar we spend in mitigation,” said John Davies, senior wildland fire specialist with Forsite Consultants Ltd., a B.C.-based forestry company with clients across the country.
“If we had that much money to put into prevention, into mitigation, we’d be way further ahead right now than we are.”
Currently, fuel clearing and thinning is typically an expense for municipalities, First Nations or forestry companies that undertake the work. Some government grants are available for such work, and for prescribed burns, but that funding is limited. One B.C. program, for example, offers annual $150,000 grants for WUI treatments.
With fuel treatment costs of about $10,000 a hectare, $150,000 doesn’t go very far, Mr. Davies said, adding that a cycle of short-term grants also works against the longer-term, integrated landscape planning experts say is needed to reduce wildfire threats.
Commercial markets for what has traditionally been seen as lower-value wood could provide an incentive for companies, First Nations and local governments to do more thinning and clearing.
Biomass, in the form of wood products, has the potential to replace some fossil fuels, said Gary Bull, a professor in the University of British Columbia’s faculty of forestry. “We are way behind in our thinking on that in Canada,” Prof. Bull said.
“If you look at the number of towns with district energy systems, they are few and far between, but most Scandinavian towns run on district energy, and cities like Stockholm and Copenhagen would run basically on chips and wood pellets.”
District energy systems are networks that provide heating for multiple buildings from one central plant or a connected network. Some systems also provide cooling and power. According to the International Energy Agency, 90 per cent of heat supplied in district networks globally is produced from fossil fuels, especially in the two largest markets of China and Russia. But such systems can also run on geothermal, solar or wood waste, potentially playing a role in reducing greenhouse gas emissions and making better use of wood fibre.
Conservation groups and others, including the Green Party of B.C., have raised red flags over the growing pellet industry in B.C., alleging pellet companies are harvesting old-growth forests to make their products – which the industry disputes.
Researchers are also looking into the potential for different species to reduce wildfire risk. Plant species differ in their flammability, and when fire-resistant trees and shrubs are present, they can slow down a fire. (In extreme conditions, Dr. Flannigan cautions, virtually everything burns “except rock and water.”)
Revised practices might also involve less aerial spraying of herbicides, which are used to discourage species deemed to be of lesser commercial value, such as aspen and birch. But those species hold more moisture than some coniferous trees like Douglas fir, making them less flammable, especially in summer months when they are covered in green leaves.
“We don’t necessarily have to plant aspen, but we should stop using chemical treatments and mechanical treatments to get rid of something that is a natural firebreak,” Dr. Kurz said.
With wildfires still burning and hot, dry conditions prevailing in much of the country, he expects wildfire-related emissions to keep climbing.
Forest carbon accounting is complex, and controversial. In his April report, environment commissioner Mr. DeMarco flagged a lack of transparency in Canada’s accounting for human activities on forestry emissions. The report echoed concerns raised by environmental group Nature Canada that Canada is significantly underreporting logging emissions.
That issue remains unresolved. But Dr. Kurz and others say the time for corrective action in the woods is now.
“We’re reaching areas burned now that are totally unprecedented,” Dr. Kurz said, referring to wildfires in B.C., where he is based. “And we’ve done this in 2017, 2018, 2021 and now 2023. Like, how much more evidence do we need?”