A Record of Decline
The Rhône Glacier, source of the Rhône River in the Swiss Alps, provides a measurable record of climate change. At its last major peak during the Little Ice Age around 1860, its tongue reached far down into the valley, ending about 3 kilometers farther and 600 meters lower in elevation than it does today. Since systematic surveys began in 1874, the glacier has been in a near-constant state of retreat. By 2016, its total length was measured at 9.7 kilometers.
The rate of retreat has accelerated dramatically. Between 1980 and 2016, the glacier pulled back approximately 1.3 kilometers, an average rate of about 36 meters per year. On a hot day, it can lose 10 to 12 centimeters of ice. This rapid melting led to the formation of a new proglacial lake at its snout, which first appeared in 2005 and is now the official source of the Rhône. By 2024, this lake had grown to a considerable size, measuring around 550 meters long and 400 meters wide. The glacier's overall volume has shrunk by an estimated 60% since 1850. This retreat is tracked by the Swiss Glacier Monitoring Network (GLAMOS), which uses methods like measuring changes in glacier length, mass balance, and volume to document the ice loss.