Sack Lunch Seminar (SLS)

The role of ice shelves and ocean melting in ice stream dynamics


Much of West Antarctica rests on a bed below sea level, making it vulnerable to external forcing at its margins. The floating ice shelves at its margin are thought to protect against speedup of grounded ice and unstable retreat of its grounding line (the boundary between grounded and floating ice). It was not until relatively recently, however, that satellite observations have shown evidence of the role played by ice shelves in ice sheet flow. The implication is that the ocean can potentially drive large changes in the Antarctic Ice Sheet by melting the base of ice shelves. This process is complicated and indirect, and there is a clear need to understand this process through modeling.


Many glaciological models have difficulty representing grounding line migration, however, and to date none have been successfully coupled with a realistic ocean model. I will present results from a new coupling framework in which an ice model capable of representing the grounded-to-floating transition interacts with an isopycnal ocean cavity model. Results are preliminary, but they suggest that the grounded response to external ocean forcing can be quite strong and nonlinear.