Preprints
https://doi.org/10.5194/egusphere-2024-208
https://doi.org/10.5194/egusphere-2024-208
14 Mar 2024
 | 14 Mar 2024

The cryostratigraphy of thermo-erosion gullies in the Canadian High Arctic demonstrates the resilience of permafrost

Samuel Gagnon, Daniel Fortier, Etienne Godin, and Audrey Veillette

Abstract. Thermo-erosion gullies (TEGs) are one of the most common forms of abrupt permafrost degradation. They generally form in ice-wedge polygonal networks where the interconnected troughs can channel runoff water. Although TEG can form within a single thawing season, it takes them several decades for their complete stabilization. While the inception of TEGs has been examined in several studies, the processes of their stabilization remain poorly documented, especially the ground ice patterns that form following permafrost aggradation in stabilizing TEGs. For this study, we investigated the impacts of two TEGs in the Canadian High Arctic (Bylot Island, NU, Canada) on ground ice content, cryostratigraphic patterns, and geomorphology to examine permafrost recovery following thermal erosion in ice-wedge polygonal tundra. We sampled 17 permafrost cores from two TEGs – one still active (since 1999) and one stabilized (>100 years old) – to describe the surface conditions, interpret the cryostratigraphic patterns, and characterize the state of permafrost after TEG stabilization. We observed that although the TEG caused discernable cryostratigraphic patterns, ground ice content and active layer thickness of the TEGs were comparable to measurements made in undisturbed conditions. We also noted that once stabilized, TEGs permanently (at the Anthropocene scale) alter landscape morphology and hydrological connectivity. We concluded that although the formation of a TEG has profound effects on the short/medium term and leaves near permanent geomorphological and hydrological scars in periglacial landscapes, on the long term, High Arctic permafrost can recover and return to geocryological conditions similar to those pre-dating the initial disturbance. This suggests that in stable environmental conditions undergoing natural variability, permafrost can persist longer than the geomorphological landforms in which it forms.

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Samuel Gagnon, Daniel Fortier, Etienne Godin, and Audrey Veillette

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-208', Sebastian Wetterich, 11 Apr 2024
  • RC2: 'Comment on egusphere-2024-208', Go Iwahana, 26 May 2024
Samuel Gagnon, Daniel Fortier, Etienne Godin, and Audrey Veillette
Samuel Gagnon, Daniel Fortier, Etienne Godin, and Audrey Veillette

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Short summary
Thermo-erosion gullies (TEGs) are one of the most common forms of abrupt permafrost degradation. While their inception has been examined in several studies, the processes of their stabilization remain poorly documented. For this study, we investigated the impacts of two TEGs in the Canadian High Arctic. We found that while the formation of a TEG leaves permanent scars in landscapes, on the long term, permafrost can recover to conditions similar to those pre-dating the initial disturbance.