It’s not even summer yet, but 2023 is set to be the worst wildfire year in recent memory. As of June 5, wildfires in Canada have destroyed 3.3 million hectares of land, including 2.2 million hectares of managed forest land, according to Werner Kurz, a senior scientist with the Canadian Forest Service.
“People sometimes say, ‘Is this the new normal?’ And the answer is unequivocally this is not the new normal … We’re on a trajectory of continuously worsening situations due to climate change,” he said.
“Our emission reduction targets literally go up in smoke as a result of these wildfires.”
But it’s not just the initial increase in emissions from the fires that are a cause for concern. When the fires damage or destroy trees, deadwood, and fine organic matter on the forest floor, they also disrupt the ecosystem’s ability to sequester carbon. This is not a trivial amount, as Canada’s boreal forests alone are keeping more than 25 gigatonnes of carbon from the atmosphere.
On average, Canada’s managed forests store around 208 tonnes of carbon per hectare, though this varies on forest age, location and many other factors.
Forests store carbon as they grow. Eventually, trees die, or parts fall off, becoming deadwood. Then there’s smaller pieces of plant matter that cover the forest floor.
Forest fires burn these carbon-storing materials, releasing the greenhouse gases into the air. They also kill living trees, causing them to start releasing carbon as they decay.
Forests will regrow after a wildfire. Boreal forests, for instance, are adapted to fire, and wildfires will cause the trees to release their seeds and cones, leading to new growth.
However, this regrowth, and the carbon uptake that occurs, can be impaired in an area if several fires hit it year after year, destroying the seedlings before they have a chance to reproduce, or simply destroying the seeds in the ground, Kurz explained.