The Chacaltaya glacier, 5,300m (17,400 ft) up in the Andes, used to be the world's highest ski run.
But it has been reduced to just a few small pieces of ice.
Many Bolivians on the highland plains, and in two cities, depend on the melting of the glaciers for their water supply during the dry season.
The team of Bolivian scientists started measuring the Chacaltaya glacier in the 1990s. Not long ago they were predicting that it would survive until 2015.
But now it seems, the glacier has melted at a much faster rate than they expected.
Photos taken in the last two weeks show that all that is left of the majestic glacier, which is thought to be 18,000 years old, are a few lumps of ice near the top.
Just 20 years ago skiers from all round the world would travel to Chacaltaya to say they had skied down the world's highest ski run.
Water fears
But Edson Ramirez, a scientist who has studied the region for years, says the significance of the melting glaciers goes way beyond tourism.
As well as those living on the highland plains, two of Bolivia's main cities, La Paz and El Alto, rely on the Andean glaciers for an important part of their drinking water.
The World Bank warned earlier this year that many of the Andes' tropical glaciers will disappear within 20 years.
This, the bank said, would both threaten the water supplies of nearly 80 million people living in the region, and jeopardise the future generation of hydropower.
Bolivia, Ecuador and Peru depend on that power for about half their electricity.
Mr Ramirez and his team are planning to hold a special ceremony this month to honour the loss of Chacaltaya. It is as if someone had died, he says.
Going back to the topic of Global Warming, do you think that it's the responsibility of The Bolivian/Ecuadorian/Peruvian governments to help stop, or at least slow down the speed of melting?
Im not sure if much can be done to stop the melting of the glacier, but it is the responsibility of the Bolivian gov. to provide clean water/ power to the areas that are now depraved.
They either need to find another way to get water or renew the resource, and yes it's goverment's responsiblity to slow the melting or find another way to get water.
