Antarctica and the Southern Ocean influence the global heat balance and carbon uptake, but recent anomalies in sea ice, snowfall, and heat waves challenge current understanding of the region’s response to climate change. ACCU investigates links between ice-sheet surface mass balance, sea ice, ocean temperature, and ice-shelf melt using observations, causal inference, and the coupled PARASO ice-sheet–ocean–sea-ice–atmosphere–land model. The project aims to clarify the direct and indirect connections among Antarctic climate components and assess their roles in recent and future change.