Characteristics and evolution of bedrock permafrost in the Sisimiut mountain area, West Greenland

• Main Authors: Marcer, Marco, Duvillard, Pierre-Allain, Tomaškovicová, Sona, Nielsen, Steffen Ringsø, Revil, André, Ingeman-Nielsen, Thomas
• Format: Text
• Language: English
• Published: 2022
• Subjects: Cold Mountain; Greenland; Sisimiut; Ice; permafrost
• Online Access: https://doi.org/10.5194/tc-2022-189; https://tc.copernicus.org/preprints/tc-2022-189/

Bedrock permafrost is a feature of cold mountain ranges that was found responsible for the increase of rock fall and landslide activity in several regions across the globe. In Greenland, bedrock permafrost has received so far little attention from the scientific community, despite mountains are a predominant feature on the ice-free coastline and landslide activity is significant. With this study, we aim to move a first step towards the characterization of bedrock permafrost in Greenland. Our study area covers 100 km 2 of mountain terrain around the town of Sisimiut – 68° N on the West Coast. We first acquire surface ground temperature data from 2020–2021 to model bedrock surface temperatures time series from weather forcing on the period 1850–2022. Using a topographical downscaling method based on digital elevation model, we then create climatic boundary conditions for 1D and 2D heat transfer numerical simulations at the landscape level. In this way we obtain permafrost distribution maps and ad-hoc simulations for complex topographies. Our results are validated by comparison with temperature data from two lowland boreholes (100 m depth) and geophysical data describing freezing/unfreezing conditions across a mid-elevation mountain ridge. Finally, we use regional carbon pathway scenarios 2.6 and 8.5 to evaluate future evolution of ground temperatures to 2100. Our results indicate a sporadic permafrost distribution up to roughly 400 m.a.s.l., while future scenarios suggest a decline of deep frozen bodies up to 800 m.a.s.l., i.e. the highest summits in the area.