Modelled centennial ocean warming in the Amundsen Sea driven by thermodynamic atmospheric changes, not winds

Increased ice loss from the West Antarctic Ice Sheet plays a significant role in determining future sea level rise. Much of this loss originates from within the Amundsen Sea sector, where the floating components of ice sheets, the ice shelves, are expected to melt more rapidly over the coming century. This increased melting is caused by warm waters entering the continental shelf and melting these ice shelves from below. While models project an increase in ocean warming over the coming century, the causes behind this warming are little understood. In this study, we untangle how climate change will affect ocean warming in the future by comparing ocean warming under high emissions to pre-industrial simulations. An anthropogenic signal in ocean warming first emerges between 2013 and 2018 in the simulations and continues to strengthen under high emissions forcing. We then compare the effects of stronger winds shifted southwards (wind forcing) against the impacts of a warmer, wetter atmosphere (thermodynamic forcing). We find that the thermodynamic changes are primarily responsible for the predicted Amundsen Sea warming. Under a warmer and wetter climate, the ice shelves experience an increase in the poleward flow of warmer waters at depth, leading to more melting.