Antarctica 6 Permafrost 6 active layer permafrost 6 Active layer 4 Deception Island 4 South Shetland Islands 4 West Antarctica 4 air temperature 4 climate change 4 snow cover 4 thermal regime 4 topography 4 Antarctic Peninsula 2 Antarctic peninsula 2 Climate change 2 Crater Lake 2 Decreasing thaw depth 2 Oregon 2 Otto Nordenskjöld Museum 2 Snow Hill Island 2 Snow insulation 2 South Shetland 2 Thermal regime 2 Thermal state 2 United States 2 climate effect 2 crater lake 2 embankment 2 frozen ground 2