Abstract
Spitsbergen has recently experienced a continuous deglaciation process, linked to both glacier front retreat and lowering of the glacier surface. This process is accompanied by permafrost aggradation from the top of the slopes down to the glacier. Here, the authors determine the rate of permafrost expansion in this type of vertical profile. To this end, seven nunataks across the island were analysed using Landsat satellite imagery, a high-resolution digital elevation model (ArcticDEM), and geoinformation software. Over the last 24–31 years, new nunataks gradually emerged from the ice cover at an average linear rate of 0.06 m a−1 per degree of increment of the slope of the terrain at an average altitude of approximately 640 m a.s.l. The analysis showed that the maximum rate of permafrost expansion down the slope was positively correlated with the average nunatak elevation, reaching a value of approximately 10,000 m2 a−1. In cold climates, with a mean annual air temperature (MAAT) below 0 °C, newly exposed land is occupied by active periglacial environments, causing permafrost aggradation. Therefore, both glacial and periglacial environments are changing over time concomitantly, with permafrost aggradation occurring along and around the glacier, wherever the MAAT is negative.
Highlights
Glacial and periglacial environments are frequently perceived and investigated as fully differentiated entities [1,2]
Seven nunataks from different parts of Spitsbergen which represent different altitude ranges (Table 2; Figure 4), were arbitrary selected as examples of the process studied: lower nunataks reaching
Temperature variations can cause increased weathering of the slope material, while exposure to temperatures less than −1 ◦ C leads to the permafrost aggradation on the slopes and forefield surrounding the glacier
Summary
Glacial and periglacial environments are frequently perceived and investigated as fully differentiated entities [1,2]. This is mainly because permafrost is defined as a thermal state of the lithosphere: ice or rock [3,4,5,6,7], while glaciers are defined as the material consequence of the accumulation, metamorphism and movement of the different types of ice forming a glacier [8,9]. Svalbard is an area where the MAAT is −1 ◦ C or lower everywhere, which means that each part of the area exposed to direct climate influence fulfill those conditions and develops permafrost as soon as the glaciers recede In general its aggradation occurs everywhere where the heat balance on the Earth’s surface is negative, and usually is related to the mean annual air temperature (MAAT) ca. −1 ◦ C or lower [1,2,3].
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