Aletsch Glacier

The Aletsch Glacier is the largest glacier in the Alps, running about 23 kilometers through the Swiss canton of Valais in the eastern Bernese Alps. As of 2011 it covered roughly 81.7 square kilometers with a volume of 15.4 cubic kilometers, and at Konkordiaplatz, where four tributary glaciers meet, the ice reaches a maximum thickness of 905 meters. The glacier's main body flows southeast toward the Rhone valley and feeds the Massa river at its terminus, and the surrounding Jungfrau-Aletsch area was named a UNESCO World Heritage Site in 2001. It has been retreating for over a century, losing about 3.2 kilometers of length since 1870, though its great size means it responds more slowly to warming than smaller alpine glaciers.