by Phillip Meintzer was hours away by car from the biggest fires raging in the forests of British Columbia and Alberta in the summer of 2021, but the air was still thick with smoke from the Canadian infernos.
“The fires were not next door. It was a little way down the road,” 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 North American and Eurasian boreal forests created historic amounts of climate-changing carbon dioxide in 2021, according to a new study Thursday in the journal Science.
Smoke from these wildfires made up 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 usually make up only 10% of global fire emissions.
That summer was particularly dry and warm in Canada — even in the country’s boreal forests, the cold, carbon-rich ecosystems of the north. In one of them, the Marguerite River Wildland Provincial Park, more than 69,000 acres (28,000 hectares) of forest burned.
But such conditions will become more normal as climate changes, leading to more intense fire seasons that could cause more carbon emissions and reduce the amount of trees available for carbon storage, the study authors said.
“This warming that is accumulating in the arctic and boreal regions will continue,” said Steve Davis, a climate scientist at the University of California, Irvine. “So what we’re concerned about is it’s not really an anomaly. It’s like the new normal. And there will be a lot of these boreal forests on fire for 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.
That’s concerning, he said, because a lot of carbon is stored in these northern ecosystems, which are among the fastest warming in the world, according to the UN’s climate change panel.
In addition to the carbon dioxide added to the atmosphere by the boreal wildfires themselves, the loss of trees and soil from more frequent and intense wildfires could mean that the Earth is losing an important source of carbon storage. The danger scientists say is that boreal forests could flip further toward emitting more carbon than they absorb.
“A really 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.
One question related to global warming, he said, is whether a longer growing season would encourage new growth in boreal forests and pull carbon out of the atmosphere or if warming and burning would create new sources of emissions, such as the thawing of permafrost.
“We don’t know what the end of that ledger will be, whether we’ll be in the red or the black,” said Dan Thompson, a fire investigator with the Canadian Forest Service who was not involved in the investigation. “It’s a little uncertain.”
The study attributed the 2021 record for boreal wildfire emissions to dry and warm conditions in both North America and Eurasia, not just one or the other.
To reach their findings, researchers examined satellite data from 2000 through 2021 to measure how much carbon monoxide was created in the world’s boreal forests and found a steady increase over the past two decades. They then used the amount of carbon monoxide, which is easier to detect than carbon dioxide by satellites and which is produced along with that substance during fires, to find out how much carbon dioxide was being 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 as boreal wildfires become more frequent and intense, it’s more likely that the forests won’t be able to sequester as much carbon as they did in the past.
“If we see more and more of these fires,” he said, “it could be that all these forests aren’t helping us all that much anymore, but are a new source of emissions to just stack on top of human emissions and make our climate challenge even bigger.” .” ___
Follow Drew Costley on Twitter: @drewcostley.
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