And if we already see the effects of warming on the Peninsula of the West Antarctic Ice Sheet with the breaking up of these ice shelves, then those ice shelves at the northern margins of the East Antarctic Ice Sheet, extending for 8000 km over an enormous front, are a much greater concern. One part of the East Antarctic Ice Sheet partially collapsed many years ago. It is south of India, the Amery Ice Shelf, another one of these floating ice shelves that is fed primarily by the largest ice stream in East Antarctica, the Lambert Glacier. A lot of East Antarctic ice has been discharged by the Lambert Glacier to produce an embayment now occupied by the Amery Ice Shelf. It followed a subglacial trough under the ice sheet that is below sea level and extends right into the central part of the East Antarctic Ice Sheet where today ice is 4000 meters above sea level.
Ice streams drain into the sea in a number of other places along the coast of East Antarctica.
They are underlain by deep bedrock troughs that are below sea level and that extend into broad subglacial basins, also below sea level. When two-thirds of the West Antarctic Ice Sheet collapsed, most of it was grounded on land that was below sea level. It started to collapse probably 20,000 years ago, and collapse really became rapid after 14,000 years ago when sea level was rising rapidly as the Northern Hemisphere ice sheets disintegrated. It was as though the West Antarctic Ice Sheet slipped on a banana peel. It lost its support from the bed and just spread out into the sea.