Preprints
https://doi.org/10.5194/tc-2021-302
https://doi.org/10.5194/tc-2021-302

  20 Nov 2021

20 Nov 2021

Review status: this preprint is currently under review for the journal TC.

Thermokarst lakes formed in buried glacier ice: Observations from Bylot Island, eastern Canadian Arctic

Stéphanie Coulombe1,2,3, Daniel Fortier2,3, Frédéric Bouchard3,4, Michel Paquette5, Denis Lacelle6, and Isabelle Laurion7 Stéphanie Coulombe et al.
  • 1Polar Knowledge Canada, Cambridge Bay, X0B 0C0, Canada
  • 2Department of Geography, Université de Montréal, Montréal, H2V 2B8, Canada
  • 3Centre for Northern Studies, Université Laval, Quebec City, G1V 0A6, Canada
  • 4Department of Applied Geomatics, Université de Sherbrooke, Sherbrooke, J1K 2R1 Canada
  • 5Department of Geography and Planning, Queen’s University, Kingston, K7L 3N6, Canada
  • 6Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, K1N 6N5, Canada
  • 7Centre Eau Terre Environnement, Institut national de la recherche scientifique, Quebec City, G1K 9A9, Canada

Abstract. In formerly glaciated permafrost regions, extensive areas are still underlain by a considerable amount of glacier ice buried by glacigenic sediments. Although the extent and volume of undisturbed relict glacier ice are unknown, these ice bodies are predicted to melt with climate warming but their impact on landscape evolution remains poorly studied. The spatial distribution of buried glacier ice can play a significant role in reshaping periglacial landscapes, in particular thermokarst aquatic systems. This study focuses on lake initiation and development in response to the melting of buried glacier ice on Bylot Island, Nunavut. We studied a lake-rich area using lake-sediment cores, detailed bathymetric data, remotely sensed data and observations of buried glacier ice exposures. Our results suggest that initiation of deeper thermokarst lakes was triggered by the melting of buried glacier ice. They have subsequently enlarged through thermal and mechanical shoreline erosion, as well as vertically through thaw consolidation and subsidence, and they later coalesced with neighbouring water bodies to form larger lakes. Thus, these lakes now evolve as “classic” thermokarst lakes that expand in area and volume as a result of the melting of intrasedimental ground ice in the surrounding material and the underlying glaciofluvial and till material. It is expected that the deepening of thaw bulbs (taliks) and the enlargement of Arctic lakes in response to global warming will reach undisturbed buried glacier ice, if any, which in turn will substantially alter lake bathymetry, geochemistry and greenhouse gas emissions from Arctic lowlands.

Stéphanie Coulombe et al.

Status: open (until 15 Jan 2022)

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Stéphanie Coulombe et al.

Stéphanie Coulombe et al.

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Short summary
Buried glacier ice is widespread in Arctic regions that were once covered by glaciers and ice sheets. In this study, we investigated the influence of buried glacier ice on the formation of Arctic tundra lakes on Bylot Island, Nunavut. Our results suggest that initiation of deeper lakes was triggered by the melting of buried glacier ice. Given future climate projections, the melting of glacier ice permafrost could create new aquatic ecosystems and strongly modify existing ones.