Coastal erosion reveals the extent of ice-rich permafrost underlying active layer on the Arctic Coastal Plain in the Teshekpuk Lake Special Area of the National Petroleum Reserve – Alaska. Credit: Brandt Meixell, USGS
In Northwestern Canada, glaciers and permafrost have preserved ancient ground ice and glacial sediments dating back to the late Pleistocene, tens of thousands of years ago. However, recent climate changes have caused temperatures and rainfall to rise, thawing out the permafrost and dramatically altering the landscape. These climate-driven environmental changes will have long-lasting effects on both the terrain and the ecosystem. Researchers from the Government of Northwest Territories as well as the University of Ontario, University of Ottawa and the University of Auckland in New Zealand, conducted a study to determine how drastic these effects are.
In order to determine how much the landscape was being altered by the climate-driven thaw of permafrost, researchers used satellite imagery and statistical software to measure and map small landslides that occur when previously frozen soil is thawed out. These small landslides are known as “thaw slumps.†These thaw slumps alter the landscape by transforming smoother terrain, held together by permafrost, into slumps of uneven ground. These small landslides can expose previously covered ground ice, further accelerating the rate at which the landscape is altered and creating a positive feedback loop. Sediment deposited by these small landslides are often carried away by streams and rivers which have lasting ecological impact on downstream watersheds and environments.
By mapping out these thaw slumps and examining the concentrations of suspended sediment in streams, researchers were able to form a comprehensive picture of the environmental effects of degrading permafrost. Altogether, these geological processes “signal the climate-driven renewal of deglaciation and postglacial permafrost landscape evolution.â€
Image credit: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey
The accelerating pace at which these changes to the landscape occur has also extensively affected coastal areas. Sections of Banks Island and Victoria Island in the Canadian Arctic have been drastically altered with the degradation of permafrost and slumping of terrain.
Permafrost has long been one of the strongest indicators of climate change, and degradation of permafrost is the main mechanism behind climate-driven changes to the landscape in polar regions. Alterations to the landscape will have long lasting impacts on the ecosystem as well as liberate carbon held by ground ice. The scale of permafrost degradation, its effects on the terrain as well as its recent intensification indicate that we are on the verge of significant, climate-driven geological changes.
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