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TitleGround ice degradation and thermokarst terrain formation in Canada over the past 16,000 years
AuthorWolfe, S AORCID logo; O'Neill, H BORCID logo; Duchesne, CORCID logo; Froese, D; Young, J M; Kokelj, S V
SourceASM2021: ArcticNet Annual Scientific Meeting; 2021 p. 1
Alt SeriesNatural Resources Canada, Contribution Series 20210248
MeetingASM2021: ArcticNet Annual Scientific Meeting; December 6-10, 2021
File formatpdf
Subjectssurficial geology/geomorphology; environmental geology; Nature and Environment; Science and Technology; permafrost; ground ice; periglacial features; thermokarst; ice-wedge polygons; hummocks; peat; climate effects; models; landslides; slumps; subsidence; Climate change; cumulative effects; gullied terrain; lithalsas; palsas; Phanerozoic; Cenozoic; Quaternary
ProgramClimate Change Geoscience Permafrost
Released2021 12 01
AbstractThermokarst results from thawing of excess ground ice in permafrost. Thermokarst processes and landforms are controlled by ground ice type and distribution, and the patterns of ground ice loss over time. Recent acceleration of varied thermokarst processes across diverse Canadian permafrost terrains make for a challenging task in predicting landscape-scale thaw trajectories. Using existing ground ice models, we examined modelled amounts and spatial extent of ground ice loss relative to ground ice maxima in the last ca. 16 ka BP for relict, segregated and wedge ice. We relate observed thermokarst features with the nature of ground ice development and loss in different environments (cold continuous permafrost, discontinuous permafrost, and no current permafrost). In cold, continuous permafrost areas where ground ice loss has been limited over the last 16 ka BP, thermokarst processes include active layer detachments and slumps in segregated and relict ice, gullying and ponding in ice wedge troughs, and the cyclical development of shallow thermokarst ponds in segregated ice. With ground ice loss in discontinuous permafrost, thermokarst processes are wide-ranging. Slumps, subsidence, and collapse of lithalsas, palsas and peat plateaus occur from thawing of segregated ice, thermokarst ponds from melting wedge and segregated ice, and involuted terrain from melting of relict or segregated ice. In former permafrost terrain, evidence of thermokarst includes former ice wedge polygons, collapsed lithalsas, and irregular hummocky terrain. The relations between modelled ground ice loss and observed thermokarst landscapes assist in understanding present-day processes and in predicting future thermokarst landform evolution with a changing climate.
Summary(Plain Language Summary, not published)
We examine the relationship between the modelled ground ice loss in permafrost terrain to thermokarst processes and landforms in Canada.

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