Rapid Thaw of World's Permafrost Could Release 'Sleeping Giant,' Scientists Warn

Arctic, permafrost thaw, landslide
A landslide in the Arctic caused by rapid permafrost thaw. Carolyn Gibson, University of Guelph PhD student

Rapidly thawing permafrost in the Arctic could double the warming effect produced by greenhouse gases that are being released from the ground, potentially exacerbating climate change. That's according to researchers.

This "sleeping giant" hidden in the tundras of Canada and other northern regions around the world could also transform entire landscapes in a matter of months, Merritt Turetsky, the Canada research chair in the department of integrative biology at the University of Guelph, in Ontario, and colleagues argue in a report featured in the journal Nature.

Research has shown that the Arctic region is currently warming around twice as fast as the global average, and this is causing permafrost—or frozen soils—to thaw, often for the first time in thousands of years.

"As the temperature of the ground rises above freezing, microorganisms break down organic matter in the soil," the authors wrote in the article. "Greenhouse gases—including carbon dioxide, methane and nitrous oxide—are released into the atmosphere, accelerating global warming."

This is particularly worrying given that Arctic permafrost holds twice as much carbon as the entire atmosphere—almost 1,600 billion tonnes, the researchers say.

"Current models of greenhouse-gas release and climate assume that permafrost thaws gradually from the surface downwards," the authors wrote. "Deeper layers of organic matter are exposed over decades or even centuries, and some models are beginning to track these slow changes."

However, this kind of research, which looks at gradual processes, ignores what is perhaps an even more troubling problem—rapid permafrost collapse. This is when several meters of permafrost soil—which essentially holds the ground together—becomes destabilized within days or weeks, rather than a few inches per year.

Such rapid collapse physically alters landscapes that have taken millions of years to form—in the space of months—through subsidence, flooding and landslides. Sometimes the land can sink, to be inundated with swelling lakes and wetlands. Scientists have even observed hillsides essentially liquefying.

"This abrupt thaw is changing forested ecosystems to thaw lakes and wetlands, resulting in a wholesale transformation of the landscape that not only impacts carbon feedbacks to climate but is also altering wildlife habitat," Miriam Jones, co-author of the report from the United States Geological Survey, said in a statement.

In contrast to gradual thawing, abrupt permafrost collapse destabilizes deeper carbon stores in a shorter time span and also releases more methane—a gas which has a much stronger greenhouse effect than carbon dioxide.

"We are watching this sleeping giant wake up right in front of our eyes," Turetsky said. "It is happening faster than anyone predicted. We show that abrupt permafrost thawing affects less than 20 percent of the permafrost region, but carbon emissions from this relatively small region have the potential to double the climate feedback associated with permafrost thawing."

In addition to the adverse effects on the environment, abrupt thawing also poses a serious problem for Arctic communities. It can lead to housing becoming unstable or cause damage to infrastructure, such as roads and railway lines. It is also having an adverse effect on traditional hunting practices, as well as scientists trying to do work in the region.

"We work in areas where permafrost contains a lot of ice, and our field sites are being destroyed by the abrupt collapse of this ice, not gradually over decades, but very quickly over months to years," Turetsky said.

In light of their conclusions, the team makes a number of recommendations, including calling for more monitoring of Arctic permafrost, as well as further research into the effects of thaw on climate change.

"There is an urgent need to make substantive progress on representing the effects of abrupt thaw on the carbon cycle in Earth system models," Dave Maguire, from the University of Alaska Fairbanks, said in the statement. "This will inform policy-makers about how the release of carbon from abrupt thaw may affect the implementation of carbon management strategies to control the growth of greenhouse gases in the atmosphere."

Even though the scale of the threat posed by Arctic permafrost thaw is significant, Turetsky remains optimistic for the future.

"If we can limit human emissions, we can still curb the most dangerous consequences of climate warming," she said. "Our window for action is getting narrow, but we still have it and can make changes to save the Arctic as we know it, and the Earth's climate along with it."