Carbon emissions from boreal forest fires increased in 2021
Phillip Meintzer was hours away by car from the biggest fires that raged through the forests of British Columbia and Alberta in the summer of 2021, but the air was still thick with smoke from the Canadian underworld.
“The fires were not nearby. It was a bit far,” Meintzer, a conservation specialist with the Calgary-based environmental group Alberta Wilderness Association. “But we spent the whole month under a blanket of smoke.”
Fires like these in the boreal forests of North America and Eurasia have created historic amounts of climate-altering carbon dioxide in 2021, according to a new study published Thursday in the journal Science.
Smoke from those wildfires accounted for 23% of global fire emissions — the largest share from boreal forests since 2000, according to findings presented at the annual meeting of the American Association for the Advancement of Science. They generally represent only 10% of global fire emissions.
That summer was particularly dry and hot in Canada, even in the country’s boreal forests, the cold and carbon-dense ecosystems of the north. In one of them, Marguerite River Wildland Provincial Park, more than 69,000 acres (28,000 hectares) of forest burned.
But such conditions will become more normal as the climate changes, leading to more intense fire seasons that could create more carbon emissions and reduce the amount of trees available to store carbon, the authors said. study.
“This mass warming in the arctic and boreal regions is going to continue,” said Steve Davis, a climatologist at the University of California at Irvine. “So what worries us is that it’s not really an anomaly. It’s like the new normal. And there’s going to be a lot of these boreal forests burning in the years to come.
Much attention has been paid to wildfires in the western United States, tropical rainforests such as the Amazon and even the Australian bush. But boreal forests have received less attention, Davis said.
This is worrying, he said, because there is a lot of carbon stored in these northern ecosystems, which are among the fastest warming on the planet, according to the UN’s climate change panel. .
In addition to the carbon dioxide added to the atmosphere by boreal forest fires themselves, the loss of trees and soil from more frequent and intense wildfires could mean Earth is losing a major source of carbon. carbon storage. The danger, scientists say, is that boreal forests could tip more towards emitting more carbon than they absorb.
“A very important but complicated piece of the puzzle … is what happens to the carbon balance of boreal landscapes after large and severe fires,” said Park Williams, a climate hydrologist at UCLA who was not involved in the study. ‘study.
One question with global warming, he said, is whether a longer growing season would spur new growth in boreal forests and remove carbon from the atmosphere or whether warming and burning would create new sources of emissions, such as melting permafrost.
“We don’t know what the end of this ledger will be, if we’ll be in the red or in the dark,” said Dan Thompson, a fire research scientist with the Canadian Forest Service who was not involved in the survey. study. “It’s a bit uncertain”
The study attributed the 2021 record for boreal forest fire emissions to dry and hot conditions in North America and Eurasia, not just one or the other.
To reach their conclusions, the researchers looked at satellite data from 2000 to 2021 to measure the amount of carbon monoxide created in the world’s boreal forests and found a steady increase over the past two decades. Then they used the amount of carbon monoxide, which is more easily detectable by satellite than carbon dioxide and is created with it during fires, to determine the amount of carbon dioxide emitted.
Study co-author Davis pointed out that burning fossil fuels such as oil, natural gas and coal remains by far the largest source of carbon dioxide emissions. But he said if boreal forest fires continue to become more frequent and intense, it’s more likely that forests won’t be able to sequester as much carbon as they have historically.
“If we see more and more of these fires,” he said, “it might be that all of these forests aren’t helping us as much because they’re a new source of emissions to just pile on human emissions and to make our climate challenge even bigger.” ___
Follow Drew Costley on Twitter: @drewcostley.
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