New climate records from Sherman Island and insights into coastal West Antarctic climate variability over the last 1000 years

The West Antarctic Ice Sheet (WAIS) is vulnerable to retreat as a result of climate change and has the potential to contribute several metres to global sea level in the coming centuries. Glaciers flowing into the Amundsen Sea, in particular the Thwaites and Pine Island Glaciers, are undergoing accelerated mass loss. Ice core records from the Amundsen coast in this region are lacking and WAIS cores typically extend back in time from a few decades, up to approximately 300 years before present. Here we present new climate records from Sherman Island, located in the Abbott Ice Shelf and close to Pine Island and Thwaites. These records extend to greater than 1000 years before present, more than doubling the length of existing coastal WAIS records. Trends in stable water isotopes are compared with proximal cores to set the Sherman Island data into a regional spatial context over the last few hundred years. We find that Sherman Island demonstrates no overall trend in stable water isotope ratios or in accumulation rate over the last 50 to 100 years, in contrast to other sites, and we relate this finding to previously identified changes in the Southern Annular Mode and Amundsen Sea. We investigate atmospheric transport to the site using reanalysis data and records of chemical impurities in the Sherman Island samples. The data present an exciting and significant new contribution to palaeoclimatic datasets and reconstructive efforts including the PAGES-2k network. Importantly, taken together the records from this unique site will help to set the current changes in this highly vulnerable sector of the WAIS into the context of the last millennium.