The Antarctic Ice Sheet’s contribution to global sea level rise has accelerated in the past decade and is expected to increase further in the future, with implications for coastal regions worldwide. At present, its mass loss is mainly driven through the interaction with the surrounding Southern Ocean: at the fringes of the ice sheet, enhanced melting and calving cause glaciers to accelerate and retreat. The underlying processes and their influence on future mass losses can be examined with numerical models that encompass the dynamics of the ice sheet as well as melting physics at the ice-ocean interface. Understanding these processes is particularly important because glacier retreat can trigger – and might have already triggered - an irreversible collapse of marine regions such as the West Antarctic Ice Sheet that stores more than 3 meters of sea-level rise.