Wildfires that ravaged Canada's forested lands last year emitted more greenhouse gases than some of the top-emitting countries, a study found on Wednesday, casting doubt on the emissions budgets of countries that rely on forests as carbon stores.
Last year's wildfires released 647 megatons of carbon, more than the emissions of seven of the top 10 emitters in 2022, including Germany, Japan and Russia, according to a study published in the journal Nature.
Only China, India and the United States emitted more carbon dioxide than Canada during this period, and if Canada's wildfires were ranked alongside other countries, it would make the country the fourth-largest emitter in the world.
Typical emissions from Canadian forest fires over the past decade range from 29 megatons to 121 megatons. But the climate crisis caused by fossil fuel burning is resulting in drier and hotter conditions, fueling more extreme wildfires. Fires in 2023 burned 15 million hectares (37 million acres) across Canada, equivalent to about 4 percent of Canada's forests.
The findings add to concerns about the world's forests' role as long-term carbon sinks for industrial emissions — a problem that may actually be exacerbated by wildfires.
The concern is that the global carbon budget – an estimate of how much greenhouse gas the world can continue to emit while keeping temperature rise to within 1.5°C (2.7°F) above pre-industrial levels – is based on an imprecise calculation.
“If our goal is truly to limit the amount of carbon dioxide in the atmosphere, we need to adjust the amount of carbon that is allowed to be emitted through the economy depending on how much carbon forests do or don't absorb,” said study author Brendan Byrne, an atmospheric scientist at NASA's Jet Propulsion Laboratory.
The study found that the extremely hot temperatures Canada experienced in 2023 are on track to become more common by the 2050s, which would likely lead to severe fires across the 347 million hectares (857 million acres) of forested land that Canada relies on for carbon storage.
Worsening wildfires and the carbon they release are not counted in Canada's annual greenhouse gas emissions inventory.
According to the country's 2021 National Contribution Strategy, carbon is counted when it is emitted from human-made sources such as industrial activity, rather than from natural disturbances in forests such as insect outbreaks or wildfires.
“No matter how you set up your accounting system, the amount of carbon in the atmosphere will continue to increase,” Byrne said.
