Rapid changes in terrain are taking place in Canada’s high Arctic polar deserts due to increases in summer air temperatures.
A new study 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. 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 meters (or about 1/3 of a mile) thick, scientists had assumed this landscape was stable. But the new research finds 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 lead author Melissa Ward Jones, a PhD candidate in the geography department at McGill University.
The research team notes that:
- 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, study results suggest various factors related to terrain (e.g. slope) become more important than air temperature in maintaining active slumps.
“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 coauthor Wayne Pollard, a professor in the geography department.
“Furthermore, it raises concerns about the over simplification of some studies that generalize about the links between global warming and permafrost degradation.”
The research appears in Environmental Research Letters.
The Association of Canadian Universities for Northern Studies, the Natural Sciences and Engineering Research Council, the Fonds de recherche du Québec–Nature et technologies, the David Erb Fellowship, the Eben Hobson Fellowship and the Northern Scientific Training Program funded the study.
Source: McGill University