Department Seminar: Andrew Stewart

Title: Feedbacks between polar ocean circulation and ice melt

Abstract: Oceanic melting of Antarctic ice shelves is a key component of the mass balance of the Antarctic ice sheet, and exerts global influence on climate via its connections to see level and deep water formation. The pattern and magnitude of this melt depends on the circulation of various water masses over the Antarctic continental shelf, and is particularly sensitive to intrusions of relatively warm, mid-depth waters from the open ocean. This dependence has motivated various investigations into the response of the oceanic circulation around the Antarctic margins to a changing climate. Previous studies have identified changes in the westerly winds and in the thermohaline structure over the Antarctic continental slope as having particularly strong impacts on heat content over the continental shelf, and thus on ice shelf melt. However, ocean circulation around the Antarctic margins is additionally forced by the input of meltwater from the bases of the ice shelves. This raises the possibility of feedbacks between changes in ocean circulation and ice shelf melt, which remain poorly understood due to various logistical challenges associated with simulating ocean/sea ice/ice shelf interactions around the Antarctic margins. In this talk I will discuss recent advances in isolating and understanding melt-circulation feedbacks around Antarctica, made possible by targeted regional and idealized modeling studies.