Abstract
The degradation of permanent frozen ground (permafrost) and the increase in the thickness of the active layer may be caused both by natural processes (such as global climate change) and by anthropic activity, which changes the natural environmental conditions that allow its existence, as has been widely reported to occur in the northern polar and subpolar regions. In the case of Antarctica, some scientific research stations are located in areas with permafrost, such as the Spanish Antarctic station “Gabriel de Castilla” on Deception Island. In the place where the station is located, an important increase in erosion has been observed in recent years, including the excavation of new gullies and the erosion of the coastal cliffs. In order to develop an initial analysis of the possible effects of the station on the permafrost degradation, ground temperature has been monitored since 2012 and the thickness of the active layer and the temperature, both inside and beneath the station, have also been sporadically measured. Here we show the results and discuss how the station reduces the freezing of the ground during the winter when the station is closed and facilitates the warming of the ground during the living periods of the station in the Antarctic summer. Those initial results and conclusions make it necessary to continue the study of the permafrost and the active layer in the station site by systematic monitoring of the ground temperature and the thickness of the active layer.
Highlights
Introduction and methodsSince 2010, an increase in erosion has been observed at the site where the Spanish Antarctic station “Gabriel de Castilla” (BGdC) is located on Deception Island, Antarctica (Fig. 1)
The analysis of the thickness of the active layer, ground thermal evolution and indoor/outdoor temperature monitoring at the BGdC between February 2012 and January 2015 shows a slight increase in the freezing period duration and a consequent reduction in the duration of the thawing period (Fig. 5), in a similar way to that we observed in other sites of the island and in other islands of the South Shetland archipelago
The active layer thickness derived from these ground temperature data for the 2012-2014 period is about 50 cm (Fig. 6; Table 1) the mean annual temperature of the ground in the upper 60 cm is warmer than -0.5oC (Fig. 6)
Summary
Since 2010, an increase in erosion has been observed at the site where the Spanish Antarctic station “Gabriel de Castilla” (BGdC) is located on Deception Island, Antarctica (Fig. 1). Global warming could thaw the frozen ground, increasing the thickness of the active layer, allowing more water to flow and, produce erosion on the surface This has been reported to occur in mountain regions and more widely in the northern polar territories. From the geomorphological point of view, the station lies on a low slope glacis deposit located at the base of a hill (62.8 m a.s.l.) and 15 – 20 m from the coastal scarps Those characteristics allow us to apply similar research techniques to those we have been using in Antarctica since the late 1980’s to study permafrost and active layers following the international monitoring protocols from Ground Thermal State–Permafrost (GTS-P) and Circumpolar Active Layer Monitoring (CALM) of the International Permafrost Association (IPA). We carried out a GPS-D survey of the area to allow us to explain the data (Fig. 4)
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