The map of Greenland will have to be redrawn. A new island has appeared off its coast, suddenly separated from the mainland by the melting of Greenland's enormous ice sheet, a development that is being seen as the most alarming sign of global warming.

Several miles long, the island was once thought to be the tip of a peninsula halfway up Greenland's remote east coast but a glacier joining it to the mainland has melted away completely, leaving it surrounded by sea. Shaped like a three-fingered hand some 400 miles north of the Arctic Circle, it has been discovered by a veteran American explorer and Greenland expert, Dennis Schmitt, who has named it Warming Island (Or Uunartoq Qeqertoq in Inuit, the Eskimo language, that he speaks fluently).

The US Geological Survey has confirmed its existence with satellite photos, that show it as an integral part of the Greenland coast in 1985, but linked by only a small ice bridge in 2002, and completely separate by the summer of 2005. It is now a striking island of high peaks and rugged rocky slopes plunging steeply to a sea dotted with icebergs.

As the satellite pictures and the main photo which we publish today make clear, Warming Island has been created by a quite undeniable, rapid and enormous physical transformation and is likely to be seen around the world as a potent symbol of the coming effects of climate change. But it is only one more example of the disintegration of the Greenland Ice Sheet, that scientists have begun to realise, only very recently, is proceeding far more rapidly than anyone thought.