Aug 28 (Reuters) – Wildfires that raged through Canada’s forests last year released more greenhouse gases than some of the world’s highest-emitting countries, a study found on Wednesday, challenging national emissions budgets that rely on forests as carbon stores.

Only China, India and the USA emitted more carbon dioxide during this period. If Canada were ranked by countries, it would be the fourth largest emitter in the world.

The findings heighten concerns that our planet’s forests rely on long-term carbon sinks for industrial emissions, while fires could actually exacerbate the problem.

The concern is that the global carbon budget, the estimated amount of greenhouse gases the world can continue to emit while limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels, is based on inaccurate calculations.

“If our goal is to limit the amount of carbon dioxide in the atmosphere, we need to make adjustments to how much carbon we are allowed to emit through our economy, relative to how much carbon is or is not absorbed by forests,” said study author Brendan Byrne, an atmospheric scientist at NASA’s Jet Propulsion Laboratory.

The unusually high temperatures Canada experienced in 2023 are expected to become the norm by the 2050s, according to the study. This will likely lead to severe fires in the 347 million hectares (857 million acres) of forest lands that Canada relies on for carbon storage.

According to the country’s national climate strategy for 2021, carbon is counted when it is emitted from human sources, such as industrial activities, but not when there are natural disturbances to forests, such as insect infestations or wildfires.

“The atmosphere is experiencing an increase in this carbon no matter how we set up our accounting system,” Byrne said.

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Gloria Dickie covers climate and environmental issues for Reuters. She is based in London. Her interests include biodiversity loss, Arctic science, the cryosphere, international climate diplomacy, climate change and public health, and human-wildlife conflict. Previously, she worked for 7 years as a freelance environmental journalist, writing for publications such as the New York Times, the Guardian, Scientific American, and Wired magazine. Dickie was a finalist for the 2022 Livingston Awards for Young Journalists in the international reporting category for her climate reporting from Svalbard. She is also a contributing writer to WW Norton.