Abstract
Abstract. Quantifying ground-ice volume on a regional scale is necessary to assess the vulnerability of permafrost landscapes to thaw-induced disturbance like terrain subsidence and to quantify potential carbon release. Ice wedges (IWs) are a ubiquitous ground-ice landform in the Arctic. Their high spatial variability makes generalizing their potential role in landscape change problematic. IWs form polygonal networks that are visible on satellite imagery from surface troughs. This study provides a first approximation of IW ice volume for the Fosheim Peninsula, Ellesmere Island, a continuous permafrost area characterized by polar desert conditions and extensive ground ice. We perform basic GIS analyses on high-resolution satellite imagery to delineate IW troughs and estimate the associated IW ice volume using a 3-D subsurface model. We demonstrate the potential of two semi-automated IW trough delineation methods, one newly developed and one marginally used in previous studies, to increase the time efficiency of this process compared to manual delineation. Our methods yield acceptable IW ice volume estimates, validating the value of GIS to estimate IW volume on much larger scales. We estimate that IWs are potentially present on 50 % of the Fosheim Peninsula (∼3000 km2), where 3.81 % of the top 5.9 m of permafrost could be IW ice.
Highlights
Arctic temperatures have increased twice as fast as the rest of the world over the past 50 years; a pattern that is expected to continue for the century (IPCC, 2013; AMAP, 2017)
We provide a first approximation of Ice wedges (IWs) ice volume in a High Arctic polar desert environment, the Fosheim Peninsula, to assess its sensitivity to thermokarst processes as a response to climate change
The number of polygons were slightly increased at Ellesmere Island 2 (EL2) (+3.57 %) and Ellesmere Island 3 (EL3) (+0.04 %) and equal at Ellesmere Island 1 (EL1) and Axel Heiberg Island 1 (AH1) for the Thiessen polygons method (Table 2)
Summary
Arctic temperatures have increased twice as fast as the rest of the world over the past 50 years; a pattern that is expected to continue for the century (IPCC, 2013; AMAP, 2017). Permafrost is perennially cryotic ground that is estimated to underlie up to 24 % of the Earth’s land surface (French, 2018), including vast areas in the Arctic that are threatened by climate change. The Canadian High Arctic permafrost is vulnerable to even a slight temperature increase because it lacks thermal protection from vegetation, a substantial surface organic soil layer, or thick snow cover. Subsequent melting of ground ice reinforces the disturbance on permafrost’s thermal equilibrium. These effects are already seen in the form of increased subsidence and rapid melting events (Pollard et al, 2015). Ice wedges (IWs), wedge-shaped bodies of nearly pure ice, are a ground-ice type ubiquitous in the High Arctic and in areas of continuous permafrost in general. Investigating the response of IWs to climate change is a necessity to understand future permafrost degradation
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