Permafrost melt in Canada’s high Arctic transforming terrain

The McGill University-led study published last week in Environmental Research Letters presents close to 30 years of aerial surveys and extensive ground mapping of the Eureka Sound Lowlands area of Ellesmere and Axel Heiberg Islands located at approximately 80 °N.

The research team was focusing on a particular landform – a retrogressive thaw slump (RTS). An RTS develops as the ice within the permafrost melts and the land slips down in a horseshoe-shaped feature. This leaves a steep headscarp (erosional face of the landslide), made up of unfrozen soil overlying the ice-rich permafrost.

(A) Map of northern Canada. The box shows the Eureka Sound Lowlands area on west-central Ellesmere Island and eastern Axel Heiberg Island. (B) Study area showing the Eureka Weather Station and Eureka Sound Lowlands on Ellesmere and Axel Heiberg Islands, NU.

Melissa Ward Jones/McGill University

Retrogressive thaw slumps are well documented in the low Arctic, but due to the extremely cold climate found in the high Arctic polar regions, where average annual ground and air temperatures are -16.5 °C/2.3 °F, and -19.7 °C /-3.46 °F, respectively, and the fact that the permafrost is over 500 meters (or about 1/3 of a mile) thick, it has been assumed that the landscape was stable.

The McGill-led research team found the assumption was not true. “Our study suggests that the warming climate in the high Arctic, and more specifically the increases in summer air temperatures that we have seen in recent years, are initiating widespread changes in the landscape,” says Melissa Ward Jones, the study’s lead author and a Ph.D. candidate in McGill’s Department of Geography.

The most obvious changes researchers noted was in the terrain. “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 slump Ward Jones measured was 17,000 square meters, about the size of two Canadian football fields. But she saw much larger ones from a helicopter. “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.

“Despite the cold polar desert conditions that characterize much of the high Arctic, this research clearly demonstrates the complex nature of ice-rich permafrost systems and climate-permafrost interaction,” adds Wayne Pollard, a professor in McGill’s Department of Geography and co-author on the study.

“Furthermore, it raises concerns about the oversimplification of some studies that generalize about the links between global warming and permafrost degradation.”