What the trees are telling us

Months after the fire, the burned-out forest on the logging road near Senneterre, in northwestern Quebec, still has a vaguely acrid smell. Longhorn beetles, which you can hear loudly gnawing through the dead trees, leave scatterings of bright sawdust in their wake.

Surrounded by charred trees, Fabio Gennaretti reaches down to the forest floor and scoops up a handful of soot and ash.

In a few days, we lost a lot of carbon, says Gennaretti, a forest scientist, dusting off his hands.

Senneterre has a population of only 2,700 people, but it covers a vast forested area 16,000 square kilometres in all. Located in Abitibi-Tmiscamingue, in the heart of Quebecs boreal forest, Senneterre has an abundance of lakes and streams, and is home to many small cabins and hunting lodges and a logging industry that is the towns economic driver.

After an unusually hot and dry spring, the area was overwhelmed by wildfires in early June, including a massive blaze that forced the evacuation of Lebel-sur-Quvillon. In all, more than 375 square kilometres burned this summer across Senneterre.

Senneterre Mayor Nathalie-Ann Pelchat called it a historic loss.

Its worrisome to see so much wood burning, she said. We hope we dont have to relive it, because its clear we depend on the forest.

In Senneterre, the trees are a source of employment and tourism and a natural method of regulating carbon emissions. The town is also representative of a larger challenge playing out across the country.

Canadas boreal forest has historically served as a carbon sink. Trees draw carbon from the atmosphere into their leaves, trunks and down into their roots and soil. But the warming climate and drier conditions in the past two decades have led to larger wildfires, turning the boreal forest into a growing source of carbon.

The impacts of these emissions on the atmosphere are, of course, huge, said Werner Kurz, a senior scientist with Natural Resources Canadas Forest Service. The effectiveness of our greenhouse gas emission reduction targets is going up in smoke, literally.

The amount of greenhouse gases burned in this years wildfires is estimated to be more than two and a half times that of all sectors in the Canadian economy combined, said Kurz, citing federal government data.

The transformation of the forest from carbon sink to carbon source is troubling to scientists, who warn of a feedback loop, whereby the carbon released from the boreal forest contributes to the climate change caused primarily by the burning of fossil fuels, thereby accelerating the conditions that lead to more fires.

These kinds of feedbacks are absolutely concerning, said Jennifer Baltzer, an associate professor in the department of biology at Wilfrid Laurier University in Ontario.

There is some uncertainty regarding to what extent this dynamic will play out. Forests could transition and in some cases already have from coniferous trees to less flammable deciduous trees, potentially slowing fire activity, Baltzer said.

Still, Gennaretti is worried that what hes witnessing in Abitibi-Tmiscamingue is an ecological shift. The boreal forest is adapted to fire, but not to the kind of fires that raged this summer.

The problem that we have today is that the frequency of this event will be higher in the future, he said. I think we are at the tipping point. What we are accustomed to seeing in this region will definitely change. At this point, what we see in this region is no longer in equilibrium.

As fires continue to rage in B.C. and the Northwest Territories, researchers are taking stock of this historic fire season across Canada. A staggering 15.2 million hectares have burned an area larger than the size of Greece, and nearly twice the previous record of 7.6 million, reported in 1989.

The total estimated carbon emissions from wildfires so far this year is also more than double the previous record, according to Copernicus Atmosphere Monitoring Service, a European agency.

The boreal forests of Canada and around the world which cover parts of northern Europe, Russia and beyond are estimated to store 30 to 40 per cent of all land-based carbon.

Wildfires are known to be a vital source of renewal for the boreal forest. Fires open the forest canopy, encouraging growth and supporting the establishment of new vegetation. In late August, bright green sprouts of white birch, blueberry bushes and lambskill were popping up through the ash in the Senneterre forest.

Originally from Italy, Fabio Gennaretti has been studying boreal forests since beginning his doctoral work at Universit du Qubec en Abitibi-Tmiscamingue in 2010. Now a professor of forest science, his students have been analyzing the amount of carbon absorbed in the soil comparing forests that were recently clear cut, selectively logged and one that had been untouched. The project had to be changed completely, however, after many of the testing sites burned this summer.

Gennaretti said researchers at his university try to work with the logging industry, given their role in maintaining a healthy forest. Logging is also a significant source of emissions. Forestry emitted 73 megatonnes of CO2-equivalent in 2021, according to an analysis by environmental groups, making up 11 per cent of the countrys total greenhouse gas emissions.

Overall, researchers estimate 80 to 90 per cent of the carbon in the boreal forest is stored in the soil, in the dead leaves and branches and burned material from previous fires. In some of Canadas more northern forests and peatlands, the vegetation on the forest floor can be metres deep, jammed with sphagnum and feather moss.

When we look at boreal forests, its this kind of sparse canopy cover compared to a tropical forest or temperate forest. Its very little woody biomass, said Baltzer. The carbon storage really happens below ground, and its in these thick layers of organic soil.

Baltzer has conducted research on how more of this carbon is being unleashed into the atmosphere, given the rise of more intense fires, such as during the 2014 season in the Northwest Territories.

We imagine fires burning through, and its sort of the dramatic pictures of flaming canopies, she said. But then after that moves through the soils, if those organic soils are dry, the soils themselves can smoulder for quite an extended period of time. The deeper that burns down into the soil profile, the more carbon is released.

Her research found that severe fires at sites that had already burned in recent decades can reach far below the forest floor, down into whats called legacy carbon.

What we think is happening increasingly with these really severe and deep-burning fires is that those fires gobble up all of the carbon thats been laid down in that fire-free [soil] interval, and actually start to erode older carbon that was laid down in previous fire-free intervals, she said.

The implications of growing emissions from wildfires for global climate goals are dire. A 2022 study, published in Environmental Science, estimated wildfires in North Americas boreal forests could by mid-century contribute to a cumulative net source of nearly 12 gigatonnes of carbon dioxide, or about three per cent of remaining global emissions associated with keeping temperatures within the Paris Agreements 1.5 C limit.

Yet governments dont take those numbers into account. For example, they are not tallied as part of Canadas emission targets under the Paris Agreement, even though they will far eclipse human-made emissions this year.

Kurz has been sounding the alarm for decades about the future of Canadas forests, and says the emissions from wildfires can no longer be ignored.

WATCH | Susan Ormistons report on Canadas record-breaking wildfires:

We need to have a global conversation now around the question of where climate change impacts greenhouse gas balances, whether thats in oceans or in forests or in permafrost systems, he said. Who is technically accountable for these? Is this a global problem or is that a problem of the jurisdiction within which these emissions occur?

In a recent interview, Environment and Climate Change Minister Steven Guilbeault said Canada uses the methodology of the Intergovernmental Panel on Climate Change (IPCC) to calculate the countrys emissions.

Its together globally that we decide on what are the best practices to measure and report emissions, he said. We will follow the guidelines of the IPCC as they continue evolving over time.

While carbon accounting is left to politicians and researchers, communities across Canada must respond to the immediate threats of fires and deal with the consequences.

In June, as the flames menaced Senneterre, workers carved out an eight-kilometre fire line around the town. This month, Senneterre Mayor Pelchat watched with familiarity as wildfires bore down on Yellowknife, where authorities bulldozed a similar break between the forest and the city.

We followed it closely, Pelchat said. We saw ourselves in what they were dealing with.

As fires raged in northern Quebec, Pikogan, an Algonquin Anishinaabe community near Senneterre, opened its elementary school gym to more than 100 people from Indigenous communities evacuated further north. Many hunting cabins were lost to the flames.

Lise Kistabish, Pikogans emergency services co-ordinator, said the forests are vital for Indigenous communities and that there has to be a better way to prevent wildfires from spreading.

It makes us think about a lot of things like, to be prepared in case of evacuation of this community or to make our services better, said Kistabish.

Prime Minister Justin Trudeau recently said that the federal government needs to do a better job of funding disaster-mitigation infrastructure to fend off wildfires. Guilbeault acknowledged Ottawa needs to do more to prevent them from spreading in the first place.

We are doing some things on the forest management [side] to try and prevent and reduce forest fires, Guilbeault said. Its good work weve been doing, but its clearly not sufficient and we need to do more of it in the coming years.

The scale and power of the fires, however, makes mitigation a daunting task. Kurz pointed out that the forested area of the Northwest Territories, for example, is roughly 20 times the entire territory of the United Kingdom, yet only has a population of 45,000.

With that population density, it is virtually impossible to suppress the fires that are out there, he said. We can, of course, fight fires and thats whats very successfully being done in some areas. But the notion that Canadians have to work harder to put out these fires is just not realistic.

Kurz said theres no silver bullet when it comes to mitigating the changes in our forests.

The federal government has committed to planting two billion trees by 2030, an initiative experts say could help increase carbon sequestration. But even then, it will take many more years until those trees are mature and storing more carbon.

WATCH | How trees store carbon:

There are ways to address the problem, Kurz said, starting with reducing the burning of fossil fuels. We can also change forest management to reduce the risk of future wildfire emissions, he said. That begins with a greater emphasis on thinning out forests and prescribed burns to reduce the potential fuel in the landscape. Allowing more broadleaf deciduous trees, such as aspen and birch, back into the timber-managed landscapes would also help.

After touring the burned forest, Gerannetti walked through a vibrant and lush stretch of jackpine that had escaped the June wildfire. It was the perfect illustration, he said, of how a healthy forest sequesters carbon.

At an especially spongy patch, he slid his shovel into the ground and pulled out a handful of moss, rolling it through his fingers.

Accumulating this through time, he said, it takes a lot of years.

Additional reporting by Susan Ormiston and Jill English

Top image: Ousama Farag | Editing: Andre Mayer