DATE: May 23, 2019
SNIP: A McGill-led study published recently 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 focuses on a particular landform (known as a retrogressive thaw slump) that develops as the ice within the permafrost melts and the land slips down in a horseshoe-shaped feature. The presence of these landforms is well documented in the low Arctic. But due to the extremely cold climate in high Arctic polar deserts (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 metres (or about 1/3 of a mile) thick, it had been assumed this landscape was stable. But the McGill-led research team found that this has not been the case.
“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.
There has been a widespread development of retrogressive thaw slumps in high Arctic polar deserts over a short period, particularly during the unusually warm summers of 2011, 2012 and 2015. The absence of vegetation and layers of organic soil in these polar deserts make permafrost in the area particularly vulnerable to increases in summer air temperatures. Despite its relatively short duration, the thaw season (which lasts for just 3-6 weeks a year) initially drives the development of slumps and their later expansion in size, as their headwall retreats. Over a period of a few years after the initiation of slumps, the study results suggest various factors related to terrain (e.g. slope) become more important than air temperature in maintaining active slumps.