The thawing of the Arctic hills is one of the main contributors to climate change

The thawing of the Arctic hills releases a significant amount of organic carbon that has been locked in frozen ground for thousands of years but may now be contributing to an already in a coach to warm up, according to new research.

The discovery comes from the study of hillsides in a region in the far north of the Russia, where researchers also found a significant and rapid increase in collapsed hillsides. Collapses feature landslides that gradually expose more permafrost for thawing – and more carbon for release.

Global climate models do not account for the once-frozen carbon released by these collapsing hills. Researchers say that needs to change.

Results were published on 15 July in The Cryosphere, a journal of the European Geosciences Union. They are the first based on the use of satellite imagery to estimate carbon release from collapsing Arctic hills.

“Permafrost landscapes are expected to change profoundly over coming decades,” said Simon Zwieback, an assistant professor at the University of Alaska’s Fairbanks Geophysical Institute and one of the authors of the research paper. “Among the many consequences of this is the release of greenhouse gases such as carbon dioxide, which can aggravate climate change.”

Similar thaws are also widespread in Russia’s Yamal Peninsula in Siberia, in northwestern Canada and in the Canadian Arctic Archipelago.

PhD student Philipp Bernhard of the School Federal Polytechnic Zurich and Irena Hajnsek from the Zurich Institute and the German Aerospace Center also worked on the research. Zwieback and Hajnsek were Bernhard’s doctorate. advisers.

Work focused on 10 43 square miles in the northern Taymyr Peninsula in Russian Siberia, an area bounded by the Byrranga Mountains to the south and the Kara Sea to the north.

They then incorporated a soil organic carbon map and made assumptions about the soil ice content and its carbon stores to calculate the amount of organic carbon released.

An ice sheet covered the entire study area approximately 82 000 years, with later periods of ice retreat and advance covering a smaller and smaller area.

A receding sheet usually leaves behind substantial amounts of ice covered with clay, sand, gravel and rocks, in especially the extent of the edges of the ice sheet. The retreating sheet that once covered the current Taymyr region created several of these ice-rich areas, called marginal ice zones. Two of these areas are within the researchers’ study area.

Visuals of the study area showed an increase in subsidence of 82 during the study period 2010-2017 to 1 404 during the period 2018-2021, with almost all of this increase occurring during the extremely hot region of 2020.

The images also showed that the annual quantity of material affected increased by approximately 82 times from the first to the second period.

“The extreme heat was aggravated by the presence of a lot of ice on the ground near the area,” Zwieback said. “This is due to the long-term legacy of past ice ages, but also because a lot of that old ice is still there because the summers are generally cool and there are no fires.

“And the ice is not well protected by insulating organic layers because there is not much life in the harsh climate”, he said. he stated.

Alaska is experiencing thaw-related subsidence, but not as much as Canada and Russia. Alaska also has other landslide deformations caused by melting permafrost, and these may contribute to climate change, Zwieback said. research on a geographical scale as large as that of the Taymyr Peninsula on thaw collapses. The work of Zwieback, Bernhard and Hajnsek shows that the release of carbon resulting from the thawing of the Arctic slopes must be taken into account in the evaluation of the carbon cycle of the Arctic. Researchers also need to quantify how much is transformed into greenhouse gases like carbon dioxide.

“The big challenge is to quantify and predict where, when and how much carbon dioxide is released,” Zwieback said.

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