 The semiarid climate of Wyoming still manages to support about a dozen small glaciers within Grand Teton National Park , which all show evidence of retreat over the past 50 years . Schoolroom Glacier is located slightly southwest of Grand Teton is one of the more easily reached glaciers in the park and it is expected to disappear by 2025 . Research between 1950 and 1999 demonstrated that the glaciers in Bridger @-@ Teton National Forest and Shoshone National Forest in the Wind River Range shrank by over a third of their size during that period . Photographs indicate that the glaciers today are only half the size as when first photographed in the late 1890s . Research also indicates that the glacial retreat was proportionately greater in the 1990s than in any other decade over the last 100 years . Gannett Glacier on the northeast slope of Gannett Peak is the largest single glacier in the Rocky Mountains south of Canada . It has reportedly lost over 50 % of its volume since 1920 , with almost half of that loss occurring since 1980 . Glaciologists believe the remaining glaciers in Wyoming will disappear by the middle of the 21st century if the current climate patterns continue . 
