Glaciers in the Andes have shrunk by up to 50 per cent since the 1970s, and some could disappear altogether, a study warns.

Researchers from France and Bolivia examined about half of all Andean glaciers and blamed an average temperature rise of 0.7C between 1950 and 1994 for the retreat. The glaciers, a source of water for tens of millions of people, are believed to be melting at their fastest rate for 300 years.

Smaller glaciers below 5,400m have lost around 1.35m in thickness each year since the late 1970s, twice the rate of the bigger, high-altitude glaciers, and could melt completely in the coming decades, according to the study, published in The Cryosphere.