21 feet, 6.4 metres

The implications of the research are dramatic given Greenland holds enough ice to raise global sea levels by up to 21ft, a disaster scenario that would result in the flooding of some of the world’s major population centres, including all of Britain’s city ports.

The latest study, presented at the American Association for the Advancement of Science, in St Louis, shows that rather than just melting relatively slowly, the ice sheet is showing all the signs of a mechanical break-up as glaciers slip ever faster into the ocean, aided by the “lubricant” of melt water forming at their base.
The Independent (UK), 17 Feb 2006