SUMMER SEA-ICE VARIABILITY IN THE EASTERN WEDDELL SEA DURING THE LAST GLACIAL STAGE AS RECORDED IN SNOW PETREL STOMACH OILS (‘MUMIYO’)

Antarctic sea ice is a critical component of the climate system, affecting a range of physical and biogeochemical feedbacks, and supporting unique ecosystems. During the last glacial stage, Antarctic sea ice was more extensive than today. However, uncertainties in both empirical data sets and climate models over the seasonal distribution and character of the sea-ice pack limit our understanding of sea-ice drivers, ecosystem response, and climate impacts. Here, we exploit a unique biological archive of conditions in the sea-ice pack: the preserved remains of regurgitated snow petrel stomach oils (sometimes referred to as ‘Antarctic mumiyo’), deposited on nunataks above the ice sheet. We present results from a sequence recovered from the Lake Untersee Oasis, central Dronning Maud Land (71°20.2’S, 13°23.6’E ), which records snow petrel foraging in the eastern Weddell Sea. By linking dietary signals in the stomach oils to modern feeding habits, we demonstrate centennial-scale variability to the summer sea-ice pack close to the Antarctic continent early in the last glacial stage (ca. 24.5-30.7 cal. ka. BP). By identifying the presence and evolution of open waters (‘polynyas’) within the sea-ice pack, the results challenge existing hypotheses which emphasise the development of an extensive, thick, multi-year ‘sea-ice cap’ as the key for positive sea ice / climate feedbacks during glacial stages.