Yosemite glacier shrinking

Lyell Glacier, which sits at an elevation of 12,000 feet in Yosemite National Park, has officially stopped moving downhill.

The modest glacier—only a quarter of a mile wide—is located atop the headwaters of the Tuolumne River, which feeds into San Francisco’s Hetch Hetchy reservoir, according to SFGate.com. Lyell has shrunk by approximately 60 percent since 1900 and thinned by about 120 vertical feet.

“[Lyell] appears to have stagnated, and we strongly suspect that it has thinned to less than half the size that would keep it moving,” said park geologist Greg Stock, who has measured the glacier for the last four years. “The most logical reason for the shrinking is because of more loss from melting snow as the climate warms.”