The United Nations said on Monday that swathes of mountain ranges worldwide risk losing their glaciers by the end of the century if global warming continues at its projected rate.

The UN Environment Programme (UNEP) said in a report that whilst nature has always observed a certain periodic rate of deglaciation, the current trends observed from the Arctic to Central Europe and South America are of a different order.

"The ongoing trend of worldwide and rapid, if not accelerating, glacier shrinkage on the century time scale is most likely to be of a non-periodic nature, and may lead to the deglaciation of large parts of many mountain ranges by the end of the 21st century," the report warned.

The report said that glaciers lost on average a mass of more than half a metre water equivalent in the period 1996-2005, which is twice the ice loss of the previous decade (1986-95) and over four times the rate of the period 1976-85.

The UNEP report comes shortly after scientists warned that they could no longer rule out a fast-track melting of the Greenland icesheet, which could see much of the world's coastline drowned by rising seas.

Earlier this year, UNEP executive director Achim Steiner said the rate of glacier disappearance made it essential that "everyone sits up and takes notice".

He said the 2009 climate convention in Copenhagen would provide the true litmus test of governments' commitment to reducing greenhouse gas emissions, the carbon pollution from fossil fuels damaging Earth's climate system.

"Otherwise, and like the glaciers, our room for manoeuvre and the opportunity to act may simply melt away," Steiner warned.