Montreal

Even in the High Arctic, researchers find permafrost thaws are changing the landscape

In the Eureka Sound Lowlands on Ellesmere and Axel Heiberg islands, the permafrost is more than half a kilometre deep, and the average air temperature is –19.7 C. But higher summer temperatures have caused the earth to collapse.

McGill study uses nearly 30 years of aerial surveillance and ground mapping

A researcher stands at the edge of a retrogressive thaw slump, where ice within the permafrost has melted, destabilizing the land. (Melissa Ward Jones/McGill University)

They show a landscape that is otherworldly and sublime, but the photos from the High Arctic nonetheless capture foreboding signs of a climate changing even faster than expected.

Near the 80th parallel, McGill University researchers have documented significant degradation in permafrost — earth that has been below freezing for two or more years — that was previously believed to be stable.

The degradation is visible from the air as collapsed earth — spans of land that are sinking into horseshoe-shaped craters.

The largest slump researcher Melissa Ward Jones measured was 17,000 square metres — about the size of two Canadian football fields. (Melissa Ward Jones/McGill University)

"Generally, when you think of the Arctic you kind of see the map and think that that area should be OK because it's so far north, but our results show that that's not the case," said Melissa Ward Jones, a PhD candidate at McGill University's geography department and the study's lead author. "This area is also vulnerable to change."

In the area they studied, the Eureka Sound Lowlands on Ellesmere and Axel Heiberg Islands, the permafrost is more than half a kilometre deep, and the average air temperature is –19.7 C.

The craters are called retrogressive thaw slumps, and the study found that higher summer air temperatures were causing them. The research uses nearly 30 years of aerial surveys and ground mapping.

Retrogressive thaw slumps were particularly frequent in the polar deserts during the unusually warm summers of 2011, 2012 and 2015, researchers said. (Melissa Ward Jones/McGill University)

Those warmer temperatures have melted the ice locked in the permafrost, Ward Jones said.

"If that ice melts out, that ice was occupying a volume within your soil and so, if it melts, you lose that volume," she said. "And so it lowers the landscapes, and it changes the surface."

The largest thaw slump Ward Jones measured was 17,000 square metres — about the size of two Canadian football fields. But she said she saw larger ones from a helicopter.

In the Eureka Sound Lowlands on Ellesmere and Axel Heiberg Islands, the permafrost is more than half a kilometre deep. (Melissa Ward Jones/McGill University)

Once a slump is formed, subsequent thaws can cause it to expand in size, the researchers say.

"If temperatures keep increasing, we'll see more and more degradation occurring," Ward Jones said. "And that degradation will cause a bunch of ecosystem and environmental changes.

"We're not exactly sure what those mean, but further research will be able to answer those questions."

With files from Jaela Bernstien

Comments

To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.