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Climate Sensitivity of High Arctic Permafrost Demonstrated by Widespread Ice Wedge Thermokarst on Banks Island, Canadian Arctic Archipelago
Robert
Fraser, Canada Centre for Mapping and Earth Observation, robert.fraser@canada.ca
Ice-wedge networks underlie polygonal terrain and comprise the most widespread massive ground ice type in continuous permafrost. Wedge ice is typically encountered at the top of permafrost, so near-surface thawing can result in subsidence of the terrain surface, ponding, and the development of high centred polygons. Studies have documented that recent permafrost warming is associated with degradation of ice-wedges at local scales (10-100 km2) in several arctic environments leading to trough subsidence and ponding of water. In this analysis we use a combination of the 1985-2017 Landsat satellite image archive, high resolution optical satellite imagery, air photos, detailed digital elevation models, and field surveys to show that ice-wedge thermokarst has been extensive over Banks Island’s 70,000 km2 landmass during a period of recent warming. End-members of this thermokarst continuum range from high-centred polygon field development on well-drained hilltops, to potential thermokarst lake initiation on flatter uplands where ice-wedge ponds have rapidly coalesced. We demonstrate that cold Arctic permafrost landscapes can be among the most thaw sensitive permafrost environments because well-developed epigenetic and anti-syngenetic ice-wedges truncated by the active layer lack the strong ecosystem protection that buffers summer warming and drives feedbacks that stabilizes thermokarst in the low Arctic. Associated Project(s): Poster Location ID: 71 Session Assigned: Wildlife and Ecosystem Services
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