Ice sheets are huge blankets of ice covering land sitting astride the polar continents. There are three – one covering Greenland, one covering West Antarctica, and the largest covering East Antarctica. The amount of ice in these ice sheets is so vast that were it all to melt, the sea would rise about 64 metres. That is not going to happen any time soon. But it does mean that the stability of these ice sheets is of critical importance.
The Greenland and West Antarctic ice sheets are now losing ice. Around much of Antarctica, floating platforms of ice known as ‘ice shelves’ act as retaining walls holding the ice sheets on the land. The collapse of some of the ice shelves along the Antarctic Peninsula is a warning sign. The Larsen B ice shelf, which was the size of Stewart Island, broke up in five dramatic weeks in 2002.