Here we provide the Palmer ice core Water-stable isotope (d18O, dD), sodium (23Na), and magnesium (24Mg) palaeo archives. The Palmer drill site (73.86 S, 65.46 W, 1897 m a.s.l.) is located on the southern part of the Antarctic Peninsula, Palmer Land. The core, firn and ice, were drilled in December 2012 to a depth of 133 m below the snow surface. The Palmer ice core covers 391 years, 1621-2011 C.E. The data were measured on the British Antarctic Survey Continuous Flow Analysis system in Cambridge, UK. Data is given both on depth and temporal (annual means) scales. The d18O and dD records were measured on a CFA laser spectroscopy system and the 23Na and 24Mg data were measured on the CFA ICP-MS setup. The ice core drilling and analysis were funded by the British Antarctic Survey, Natural Environment Research Council (NERC, Cambridge, UK), part of UK research and innovation and NERC grant NE/J020710/1. The Palmer analysis was funded by Haus der Kulturen der Welt (HKW, Berlin, Germany), in collaboration with the Anthropocene working group (AWG).

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).