Report Open Access
Christiansen, Hanne H.; Gilbert, Graham L.; Neumann, Ullrich; Demidov, Nikita; Guglielmin, Mauro; Isaksen, Ketil; Osuch, Marzena; Boike, Julia
This is chapter 12 of the State of Environmental Science in Svalbard (SESS) report 2020 (https://sios-svalbard.org/SESS_Issue3).
The observed mean annual permafrost temperature data for the period 2016-2019 at 10-20 m depths show a range from no warming in the Adventdalen, Ny-Ålesund and Barentsburg areas, up to 0.15°C/yr warming in inner Adventdalen at Janssonhaugen. This shows that there is still a response to the general warming that Svalbard has seen over the last decades. During the observation period, the mean annual air temperature declined by 0.6°C, with a particular cooling in the autumns. There was a clear reduction in the amount of precipitation of 100 mm. This caused the top permafrost temperature to decrease at all observation sites ranging from 0.2°C/yr at Kapp Linné to 0.6°C/yr in Barentsburg.
The active layer has mostly decreased slightly in thickness over the 2016-2019 period from 1 cm/yr in Ny-Ålesund to 6.5 cm/yr in Adventdalen, while two sites had small increases, 1 cm/yr at Kapp Linne and 3.5 cm/yr at Janssonhaugen. In the blockfield at Breinosa the active layer doubled to 98 cm, while in raised marine sediments in Barentsburg the active layer thinned by 18.5 cm/yr from summer 2017 to summer 2019.
The ground ice content in the Svalbard permafrost observation boreholes is largest in the permafrost in valley bottom sediments, up to 160% (relative to dry weight), with much less ice in the bedrock sites, typically below 15%. In Adventdalen the permafrost has a much higher content of ground ice, reaching 150% in the top 1-3 m, where terrestrial sediments such as loess and solifluction sediment dominate, and clearly lower ice content ~25-30% in the fluvial and marine sediments below.
The overview of the drilling equipment demonstrates clearly that Svalbard is now well-equipped for drilling boreholes with a range of equipment, allowing creation of both deep and shallow boreholes. The review of the drilling methods used for the existing observation boreholes shows that most of them, even though made for permafrost observation, did not collect cores, and some do not even have any stratigraphical record.
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