Antarctic Sea Ice Expansion and The Consequences of Missing Processes in Global Climate Models

Abstract:

Antarctic sea ice has expanded in nature, but almost no global climate model reproduces the magntitude and character of the observed trends. I will present the case for key deficiencies in models that could explain their incorrect response. The first is a lack of explicit basal ice-shelf meltwater, which is instead parameterized
crudely to give mass balance of the Antarctic ice sheet and shelves. The second is a lack of ocean waves. The third is the zonal symmetry of stratospheric ozone trends when prescribed and/or biases in the ozone distribution in models with ozone predicted. The fourth is a misrepresentation of recent trends in the tropical sea surface temperature, and the attendant errors in atmospheric teleconnection to the Antarctic. I will show integration results that illustrate how and why the first and last of these deficiencies give rise to expanding sea ice. Finally, I will discuss how sea ice physics plays a role in combination with these missing processes.