George VI Ice Shelf: past history, present behaviour and potential mechanisms for future collapse
George VI Ice Shelf is the largest ice shelf on the west coast of the Antarctic Peninsula, covering a total area of 25 000 km2. The northern ice front of George VI Ice Shelf presently marks the southernmost occurrence of recent ice-shelf retreat on the Antarctic Peninsula and according to some predictions the ice shelf is close to its thermal limit of stability. If these predictions are accurate and we are witnessing the first stages of retreat then it is critical that we take the opportunity to examine the ice shelf in its pre-collapse phase. This paper provides a review of the geological evolution, glaciology and interactions between the ocean and the atmosphere. We also discuss the present behaviour of the ice shelf, in the context of recent retreat of its northern and southern ice fronts, and outline several possible mechanisms for future ice shelf collapse. What emerges from this review is that the stability of George VI Ice Shelf is sensitive not only to the recent rapid regional atmospheric warming on the Antarctic Peninsula which has led to the gradual retreat of the northern and southern ice shelf fronts, but also to changes in ocean circulation, particularly intrusions of warm Upper Circumpolar Deep Water onto the continental shelf. It is likely that any future change in the stability of George VI Ice Shelf will involve a combined atmospheric and oceanic forcing.(Published Online February 28 2007)
(Received September 12 2005)
(Accepted May 26 2006)
Key Words: Antarctic Peninsula; Circumpolar Deep Water; ice shelf retreat; 20th century warming; Quaternary history.