Peter 1st Island is situated in the Bellingshausen Sea, a region that has experienced considerable climate change in recent decades. Here we present data from the first firn core drilled on Peter 1st Island, spanning the period 2002-2017 CE. The record includes major ion chemistry (Br-, Cl-, SO42-, Na+, Ca2+, Mg2+) used to annual layer count the ice core and calculate the annual snow accumulation. The stable water isotope record is presented as annual averages, which are related to surface air temperatures across the Amundsen-Bellingshausen Seas, and the adjacent Antarctic Peninsula. The ice core drilling and analysis were funded by Ecole Polytechnique Federale de Lausanne, the Swiss Polar Institute, and Ferring Pharmaceuticals Inc and the British Antarctic Survey, Natural Environment Research Council (NERC, Cambridge, UK).

These datasets show how lake water-pressure fluctuated through time over several months in seasonally-frozen catchments in winter. These catchments were in three settings: the lowland Finnish Arctic, an alpine valley and a high cirque in Switzerland. The water-pressure data are accompanied by water temperature and (except for Orajarvi), ground temperature for the same periods. Together, they were used to detect and quantify the water content of snow falling on the lake surfaces. The locations, method of data collection and analysis and the results are described in detail in Pritchard, H. D., Farinotti, D., & Colwell, S. (2021). This work was funded by Natural Environment Research Council (UK) core funding to the British Antarctic Survey, and a fellowship from the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, CH-8903 Birmensdorf, Switzerland.