Thaw of the Canadian permafrost

Permafrost is thawing in the Arctic so fast that scientists are losing their equipment

Instead of a few centimetres of thaw a year, several metres of soil can destabilize within days

The Canadian Press · 2 May, 2019Abrupt permafrost thawing has caused a large landslide into a side channel of the Mackenzie River in the Northwest Territories. Permafrost in some areas of the Canadian Arctic is thawing so fast that it's gulping up equipment left there to study it. (Carolyn Gibson/Canadian Press)

"The ground thaws and swallows it," said Merritt Turetsky, a University of Guelph biologist whose new research warns the rapid thaw could dramatically increase the amounts of greenhouse gases released from ancient plants and animals frozen within the tundra.

"We've put cameras in the ground, we've put temperature equipment in the ground, and it gets flooded. It often happens so fast we can't get out there and rescue it.

"We've lost dozens of field sites. We were collecting data on a forest and all of a sudden it's a lake."

Turetsky's research, published this week in the journal Nature, looks at the rate of permafrost thaw across the Arctic and what its impact could be on attempts to limit greenhouse gas emissions that cause climate change.

It's been known for years that the vast belts of frozen soil that underlie much of the North are thawing as the Arctic warms. That releases greenhouse gases as organic carbon from plants and animals, once locked away in the ice, thaws and decomposes.

'Crazy liquefication'

Climate scientists have assumed a slow, steady erosion of permafrost and a similar pace of carbon release. Turetsky and her colleagues found something different.

Instead of a few centimetres of thaw a year, several metres of soil can destabilize within days. Landscapes collapse into sinkholes. Hillsides slide away to expose deep permafrost that would otherwise have remained insulated.

Thawing permafrost and ice are visible along the coast of the Mackenzie Delta. (Roger MacLeod/Natural Resources Canada)

"Permafrost at [that] depth, even 100 years from now, probably would still be protected in the soil," she said. "Except here comes this really crazy liquefication where this abrupt thaw really churns up this stuff."

Wildfires, becoming larger and hotter every year over the Canadian boreal forest, are also causing rapid permafrost thaw.

Nearly one-fifth of Arctic permafrost is now vulnerable to rapid warming, Turetsky's paper suggests. Plenty of it is in Canada, such as in the lowlands south of Hudson Bay.

Soil analysis found those quickly thawing areas also contain the most carbon. Nearly 80 per cent of them hold at least 70 kilograms of carbon per cubic metre.

That suggests permafrost is likely to release up to 50 per cent more greenhouse gases than climate scientists have believed. As well, much of it will be released as methane, which is about 30 times more potent as a heat-trapping gas than carbon dioxide.

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"These are minimum estimates," Turetsky said. "We've been very conservative."

Despite the rapid thaw, it'll be decades before the extra carbon release starts to influence global climate. "We've got a bit of time."

The abrupt collapsing of permafrost, however, will affect northerners long before that.

"The landscape is going to be affected more and more every year by permafrost degradation," Turetsky said.

"We've got a lot of people living on top of permafrost and building infrastructure on top of permafrost. It's enough to sink northern budgets."

An earlier version of this Canadian Press story incorrectly said methane is about 30 per cent more efficient at trapping heat than carbon dioxide. In fact, it's about 30 times more efficient at trapping heat than carbon dioxide.

May 03, 2019 8:27 AM ET