The latest two to fall below the 25 acre threshold were Miche Wabun and Shepard. Each had shrunk by roughly 55 percent since the mid-1960s. The largest remaining glacier in the park is Harrison Glacier, at about 465 acres. Some glaciers, such as in the Himalayas, could hold out for centuries in a warmer world. But more than 90 percent of glaciers worldwide are in retreat, with major losses already seen across much of Alaska, the Alps, the Andes and numerous other ranges, according to researchers in the United States and Europe.
The area of the Rocky Mountains now within Glacier National Park once boasted about 150 glaciers, now around 37. A handful of the park's largest glaciers could survive past 2020 or even 2030, but by that point the ecosystem would already be irreversibly altered. Geological evidence points to the continual presence of glaciers in the area since at least 5000 B.C. Glaciers have been on this landscape continually for 7,000 years, and we're looking at them disappear in a couple of decades.