A numerical model of ice-stream retreat during the Holocene period of rising sea-level has been constructed, and applied to one of the ice streams draining the Ross Sea sector of the West Antarctic ice sheet. The purpose of the experiment is to assess the relative significance of eustatic sea-level rise, the response of the solid Earth to the changing ice load, and the formation of the Ross Ice Shelf on retreat of the ice-stream grounding line to its present position in the Ross embayment. An underlying hypothesis is that marine ice sheets (such as that in West Antarctica), the ocean, and the solid Earth form a coupled dynamic system in which changes, once initiated by an external event such as rising sea-level, can proceed independently of climatic change. Ice stream E (see maps by Rose 1979) was used as a test case during development of the model.

Ocean circulation and heat transport below the Ross Ice Shelf are difficult to observe because of the thick ice cover. Numerical modeling thus provides a practical method for testing ideas about sub-ice-shelf circulation and basal melting. In this study, tidal rectification (Zimmerman 1981), tidal front formation (Fearnhead 1975), and their impact on the sub-ice-shelf environment are determined from a numerical tidal model.

The finite-element model discussed by MacAyeal and Thomas (1982) has been improved to include solution of the heat equation within each element, and to accelerate convergence to solution of the momentum-balance equations in terms of ice-shelf spreading rates. The model is now sufficiently rapid to permit both snapshot and time-marching simulations of a large ice shelf at high spatial and temporal resolution (grid size 10 km; time step 0.1 a). Here, we describe three model simulations of Ross Ice Shelf behavior.