Thawing permafrost could speed global warming, researchers warn
“Cause for serious concern”
An international team is warning that permafrost — which covers almost half of Canada — could release climate warming gases more quickly than expected.
There is “cause for serious concern,” say the scientists, who underscore “the urgent need to reduce atmospheric emissions from fossil-fuel use and deforestation” to help “keep permafrost carbon frozen in the ground.”
The Permafrost Carbon Network, which includes researchers from Siberia to Australia, estimates that a staggering 1,700 billion tonnes of carbon is stored in the top few metres of northern soils — the remains of plants and animals that have been accumulating for thousands of years.
“That is about four times more than all the carbon emitted by human activity in modern times and twice as much as is present in the atmosphere now,” the team reports Thursday in the journal Nature.
“The volumes are massive,” says co-author Charles Tarnocai, a soil scientist and permafrost researcher at Agriculture and Agri-Foods Canada.
Tarnocai, who has been doing field work in the Arctic for more than 30 years, has been instrumental in showing there is much more carbon locked in the frozen ground than previously estimated.
The “problem,” he says, is that as permafrost thaws the organic material begins to decompose, releasing carbon into the atmosphere as carbon dioxide and methane, gases that help trap heat in the atmosphere.
Tarnocai said in an interview Wednesday there is no reason to “panic.” But he and his colleagues note that “Arctic temperatures are rising fast, and permafrost is thawing.”
They say in Nature it is “crucial” to get a better handle on how fast and how much permafrost carbon could be liberated in coming decades.
“Only a handful of remote field stations around the world are collecting data to support this research, even though the permafrost zone covers about almost one-quarter of the Northern Hemisphere’s land area,” they write.
There is growing concern about methane bubbling out of Arctic lakes, icy soils rich in ancient carbon slumping and slipping down hillsides and into the Arctic Ocean and fires racing across tundra and through northern forests liberating carbon from the soil below.
Edward Schuur, at the University of Florida and lead author of the Nature report, says it’s hard to get research money for long-term observations. Yet, he says, such observations are “exactly the kind of things that are needed both in Canada and throughout the Arctic region to really detect and observe these changes.”
Co-author Merritt Turetsky, of the University of Guelph in Ontario, says Canadian scientists have generated some of the best data available on carbon in permafrost.
“But I think we are lacking in terms of current mobilization of the scientific community to really address this issue today,” she said in an interview.
Turetsky and the other 40 scientists in the permafrost network were asked to calculate how much carbon could be liberated as northern soils warm, under different climate warming scenarios.
They estimate that the northern soils will release 1.7 to 5.2 times more carbon this century than reported in previous studies.
“Even a modest release of permafrost carbon will have global impacts,” Turetsky says.
The researchers also conclude the effect on the climate could be 2 1/2 times worse than deforestation.
They also forecast that much of the northern landscape will be reshaped as global temperatures rise. Under a “high warming scenario,” which many scientists say is the path the planet is now on, they say up to 15 per cent of the top three metres of permafrost could degrade by 2040, and up to 61 per cent by 2100.
Schuur expects it to be “slow-motion change with significant impacts for our children’s generation and their children beyond that.”
“It’s not as if the whole amount [of carbon] that is in the ground is suddenly going to be in the atmosphere in 10 years,” Schuur said in an interview. “What we’re saying is it is likely to be slow, long-term emissions, but over 100 years that adds up to a significant push to the climate system.”
The scientists say the carbon released from the permafrost will be an “important amplifier” of climate change, and is in some ways more problematic than fossil fuel emissions: “It occurs in remote places, far from human influence and is dispersed across the landscape.”
“Trapping carbon emissions at the source — as one might do at power plants — is not an option,” they say. “And once the soils thaw, emissions are likely to continue for decades, or even centuries.”