Phillip Meintzer is hours away by car from the largest forest fires to burn in British Columbia and Alberta in the summer of 2021, but the air is still thick with smoke from Canada’s infernos.
“The fires are not in the neighborhood. It’s quite a long way off,” 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 North American and Eurasian boreal forests have produced historic amounts of climate-changing carbon dioxide by 2021, according to a new study published Thursday in the journal Science.
Smoke from these wildfires makes up 23% of global fire emissions – the largest share from boreal forests since 2000, said findings presented at the annual meeting of the American Association for the Advancement of Science. They typically account for only 10% of global fire emissions.
That summer was particularly dry and hot in Canada — even in the country’s boreal forests, the cold, carbon-dense ecosystems of the north. In one of these, the Marguerite River Wildland Provincial Park, more than 69,000 hectares (28,000 acres) of forest burned.
But such conditions may become more common as the climate changes, leading to more severe fire seasons that may generate more carbon emissions and reduce the amount of available trees. for carbon storage, the study authors said.
“This warming that is increasing in the Arctic and boreal regions will continue,” said Steve Davis, a climate scientist at the University of California, Irvine. “So our concern is that this is not an anomaly. This is like the new normal. And there will be more boreal forests burning in the coming years.
Much attention has been given to forest fires in the western United States, tropical rainforests such as the Amazon and even the Australian bush. But boreal forests have received little attention, Davis said.
That’s worrisome, he said, because there’s a lot of carbon stored in these northern ecosystems, which are among the fastest-warming on the planet, according to the UN panel on climate change.
In addition to the carbon dioxide added to the atmosphere from the boreal forest fires themselves, the loss of trees and soil from more frequent and intense wildfires could mean that the Earth is losing a major source of carbon storage. The danger, scientists say, is that boreal forests may end up emitting more carbon than they absorb.
“A very important but complex piece of the puzzle … is what happens to the carbon balance of boreal landscapes after large and intense fires,” said Park Williams, a climate hydrologist at UCLA was not involved in the study.
A global warming question, he said, is whether longer growing seasons will stimulate new growth in boreal forests and remove carbon from the atmosphere or whether warming and burning will create are new sources of emissions, such as melting permafrost.
“We don’t know what the end of that ledger is, whether we’re in the red or the black,” said Dan Thompson, a fire research scientist with the Canadian Forest Service who was not involved in the study. “It’s a little uncertain.”
The study attributes the 2021 record for boreal forest fire emissions to dry and warm conditions in North America and Eurasia, not just one or the other.
To reach their findings, the researchers analyzed satellite data from 2000 to 2021 to measure how much carbon monoxide was produced by the world’s boreal forests and found a steady increase over the past two years. decades. Then they used the amount of carbon monoxide, which is more easily detected by satellite than carbon dioxide and is created with it during the fire, to determine how much carbon dioxide was released.
Study co-author Davis points out that burning fossil fuels such as oil, natural gas and coal remains the largest source of carbon dioxide emissions. But he said that, if boreal forest fires continue to be more frequent and severe, it is more likely that the forests will not sequester as much carbon as they have historically.
“If we see more fires,” he said, “maybe all these forests will no longer help us because they will be a new source of emissions to increase human emissions and make . our climate challenge is even greater.” ___
Follow Drew Costley on Twitter: @drewcostley.
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