It’s no surprise that a warming climate is melting the world’s glaciers and polar ice. But no one expected it to happen this fast.

Even in better times, the Chacaltaya ski area was no competition for Aspen. Set in a bleak valley high in the Andes mountains of Bolivia, it offered a half-mile (one kilometer) swoop downhill, a precarious ride back up on a rope tow, and coca-leaf tea for altitude headaches. At 17,250 feet (5,260 meters), after all, Chacaltaya was the highest ski area in the world. “It gave us a lot of glory,” says Walter Laguna, the president of Bolivia’s mountain club. “We organized South American championships—with Chile, with Argentina, with Colombia.”

The glory days are over. Skiing at this improbable spot depended on a small glacier that made a passable ski run when Bolivia’s wet season dusted it with snow. The glacier was already shrinking when the ski area opened in 1939. But in the past decade, it’s gone into a death spiral.

By last year all that remained were three patches of gritty ice, the largest just a couple of hundred yards (200 meters) across. The rope tow traversed boulder fields. Laguna insists that skiing will go on. Perhaps the club can make artificial snow, he says; perhaps it can haul in slabs of ice to mend the glacier. But in the long run, he knows, Chacaltaya is history. “The process is irreversible. Global warming will continue.”