Emissions from Canada’s record-breaking planet-warming wildfires in 2023 were four times higher than the country’s fossil fuel emissions last year, surpassed only by the three highest-emitting countries, according to a new NASA study.

Only China, India and the United States emit more carbon per year than Canada’s wildfires between May and September 2023, according to a study published Wednesday in the journal Nature, The Canadian Press reported.

Lead author Brendan Byrne called the results “quite shocking” and raised doubts about whether Canada’s boreal forests can be relied upon in the future to absorb more carbon than they emit.

“There is concern that the more frequent fires could actually limit the forest’s ability to absorb carbon,” said Byrne, a carbon cycle scientist at NASA’s Jet Propulsion Laboratory in California.

According to the study, extreme heat and drought contributed to the wildfires that destroyed four percent of Canada’s forest area and led to the evacuation of 232,000 people.

Climate models predict that these conditions could normalize by mid-century and lead to increased fire activity.

This raises questions about one of humanity’s most important allies in the fight to slow climate change.

Canada’s forests have long absorbed more carbon than they release, and forests worldwide are thought to absorb about 25 percent of human-caused emissions. However, increased fire activity will “reduce the ability of these Canadian forests to continue to act as carbon sinks,” the study says.

Any reduction must then be reflected in global climate targets to limit global warming, Byrne said.

“When these ecosystems start releasing carbon, it’s not really accounted for and it’s not accounted for in the Paris Agreement commitments to reduce emissions,” Byrne said.

The way Canada calculates its greenhouse gas emissions from wildfires has drawn ire from environmental groups in recent years.

The study notes that Canada does not count wildfire emissions as part of its national greenhouse gas emissions. This decision deviates from United Nations guidelines, which suggest that countries should treat all carbon emissions from managed lands as human-caused.

Instead, Canada treats wildfires as natural disturbances.

Environmental groups argue that the accounting obscures the climate impacts of forestry, which accounts not for emissions from wildfires but for emissions absorbed by forests once they are old enough to be cut down, even if they have grown back after wildfires, the groups argue.

Natural Resources Canada stated that its reporting on the forest sector is based on ongoing scientific advice and review.

Canada’s greenhouse gas inventory report to the United Nations this year found for the first time that the forestry sector emits more carbon than it absorbs. The government said the revised figure was based on new estimates that the timber industry has cleared less land than was thought before 1990.

The environmental organization Nature Canada, which has conducted much of the analysis of emissions from Canadian forestry, described the change as “significant” but cautioned that emissions were still underestimated.

This report by The Canadian Press was first published August 28, 2024.