Shrinking and thinning glaciers - a phenomenon linked to climate change - are a major concern; freshwater supplies for hundreds of millions of people could be at risk, authors Peter Gilruth and Wilfried Haeberli said.

According to the UNEP and WGMS study Global Glacier Changes: Fact and Figures, the average melting rate of mountain glaciers has doubled since the turn of the millennium (2000). During the period 1996-2005 glaciers also lost twice the ice loss of the previous decade (1986-95) and over four times the rate of the period 1976-85.

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