Dynamics of seasonally thawed layer on Svalbard and the Antarctic Peninsula in the ХХI century according to modeling data

Abstract

Results of modeling of the dynamics of the seasonally thawing layer in the twenty first century made for two polar points (the Svalbard Archipelago and the Antarctic Peninsula) are discussed in the paper. The loss of thermal stability of a permafrost is usually associated with the formation of non-merging layer that transforms then into a talik. This occurs when the seasonal thaw layer is not fully frozen due to a rise in air temperature and an increase in the snow cover thickness. Climate change (warming) causes an increase in the thickness of the seasonal thaw layer. From 2001 to 2018, the rise of summer air temperature at the Barentsburg weather station was about 0.05 °C/year, while in winter −0.21 °C/year, and at the Bellingshausen weather station (Antarctic) in the summer period a slight cooling was observed. On the island of West Svalbard in 1968–2000, the average daily summer and winter air temperatures were equal to +3.74 and −9.9 °C, respectively, while in 2001–2018 these values were significantly higher, especially in winter: +4.83 and −7.12°C, respectively. On the Antarctic Peninsula, similar values were equal to: +1.03 and −4.05 °C (1968–2000) and +0.83 and −3.60 °C (2001–2018). Calculations for the conditions of the Bellingshausen weather station did show that if the snow cover thickness exceeded 0.72 m (the average climatic value) but the average values of other parameters were not changed, formation of the non-merging permafrost became possible. With regard for a possible dynamics of the air temperature, the non-merging permafrost may be frozen through at the snow cover thickness lower 0.9 m. According to calculations for the conditions of the West Svalbard Island, it follows that when the snow cover thickness exceeds 1.5 m on the ground with its humidity higher 25% and the absence of moss cover, incomplete freezing of the seasonal thaw layer and the formation of non-merging permafrost becomes possible even at present time. Using data on rates of the air temperature rise and the regional model of the climate change, we show that at the soil moisture of 18% (it corresponds to measured values of air humidity) and the snow cover thickness of 1.5 m formation of a layer of non-merging permafrost may take place in 12 years, while at the thickness of 1 m – in 24 years.