A review of changes in the coupled Antarctic climate system in models and observations

While observations have shown strong polar amplification in the Arctic, observed polar amplification in the Antarctic has been much more muted in recent decades. There have, however, been striking changes in the Antarctic climate system. Westerly winds over the Southern Ocean are strengthening, surface air temperatures have been increasing in some areas, the Antarctic ice sheet is losing mass, and the subsurface ocean is warming. Some changes have been unexpected: despite global warming, the Southern Ocean around Antarctica cooled at the surface and its sea ice expanded from the beginning of satellite observations in 1979 through 2015. Antarctic sea ice coverage subsequently dropped dramatically after 2015. This region is challenging to understand due to uncertainty in observations and extensive biases in coupled models. In this talk, I will review observed changes in key Antarctic climate indicators, their representation in climate models, and projections for the future. This will include, where possible, discussion of potential sources of model-observation discrepancy, such as model resolution, biases in atmospheric circulation and clouds, and interactions with the ice sheet.