The great glaciers of South America are disappearing at rates never seen in modern times and the continent's fresh water supply is at serious risk if the trend continues, says a new study.

Driven by global climate change, the report—published in the online academic journal Crysophere—shows that the Andean glaciers have shrunk anywhere from 30% to 50% since the 1970s.

"Glacier retreat in the tropical Andes over the last three decades is unprecedented," said Antoine Rabatel, the lead author of the study and a scientist with the Laboratory for Glaciology and Environmental Geophysics in Grenoble, France.

"Because the maximum thickness of these small, low-altitude glaciers rarely exceeds 40 meters, with such an annual loss they will probably completely disappear within the coming decades," Rabatel added.

If that happens, warned scientists, millions of people who depend on the glaciers to feed mountain streams and replenish water reserves would be at catastrophic risk.

And the Carbon Brief adds:

Retreating glaciers aren't just a visible indication of climate change - there are practical consequences, too. Another author of the new study, Alvaro Soruco, says the Andean glaciers are an important source of fresh water for nearby populations:

"Glaciers provide about 15 per cent of the La Paz water supply throughout the year, increasing to about 27 per cent during the dry season."

Rabatel explained to Carbon Brief today that as well as domestic consumption, the supply of water from mountain glaciers is important for agriculture and hydropower. So water shortages could become more problematic for local communities if the ice melt doesn't stop soon.

Successive studies show that glaciers are melting in response to climate change. But there are still relatively few studies like this one, with data spanning several decades. Such research is invaluable to climate scientists looking to get an idea of the full impact of rising temperatures are having on the world's glaciers - and what to expect in the future.

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