ANTarctic Sea Ice Evolution from a novel biological archive

Antarctic sea ice is a critical component of Earth’s climate system. Seasonal fluctuations support unique ecosystems and impact planetary albedo, ocean-atmosphere exchanges of heat and climatically-active gases (e.g. CO2), and formation of intermediate and deep water masses which create the world’s largest sink of heat and carbon. The properties of the sea-ice pack are complex: despite its climatic significance, Antarctic sea ice is challenging to observe and to model, leading to low confidence in future projections in a warming climate.The geological record offers a longer-term context for recent trends. At the last glacial maximum (LGM) a likely doubling of Antarctic sea-ice extent relative to today is hypothesised to have driven an ocean drawdown of atmospheric CO2. However, a combination of sparse empirical datasets and uncertainties in sea-ice modelling means that the properties and climatic impacts of the LGM Antarctic sea-ice pack are poorly understood. The narrow focus of the geological record on key primary producers and grazers further limits our understanding of Antarctic ecosystem responses to changes in sea ice.ANTSIE will exploit a unique biological archive of Antarctic sea-ice conditions to generate a novel ecosystem perspective on the patterns and properties of sea ice during and since the LGM. ‘Antarctic mumiyo’ sequences are preserved remains of regurgitated stomach contents from snow petrels, which feed within and at the edges of the sea-ice pack. A network of mumiyo sequences, which sample across the climatically important Weddell Sea region, will be geochemically analysed to determine snow petrel diet and sea-ice properties with unprecedented century-scale resolution. The results will be used to evaluate new state-of-the-art simulations of the LGM sea-ice pack. By integrating multi-disciplinary perspectives, ANTSIE will provide new understanding of Antarctic sea-ice controls and impacts, to facilitate improved confidence in future project.