The ground thaws and swallows: Study says permafrost melting faster than thought

“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 melt 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, melts and decomposes.

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 melt 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.

“Permafrost at (that) depth, even one hundred 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 melt.

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 melting 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 per cent more efficient at trapping heat than carbon dioxide.

“These are minimum estimates,” Turetsky said. “We’ve been very conservative.”

Despite the rapid melt, 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.”

— Follow Bob Weber on Twitter at @row1960

Bob Weber, The Canadian Press

by Canadian Press

The ground thaws and swallows: Study says permafrost melting faster than thought

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