Glacier Types: Retreating

A glacier retreats when its terminus does not extend as far downvalley as it previously did. Glaciers may retreat when their ice melts or ablates more quickly than snowfall can accumulate and form new glacial ice. Higher temperatures and less snowfall have been causing many glaciers around the world to retreat recently.

Muir Glacier in 1941, 1976, 2004Muir Glacier, located in Glacier Bay, Alaska, photographed by W. Field in Aug. 1941 (left) and B. Molnia in Sep. 1976 (middle) and Aug. 2004 (right). Note how the glacier has retreated to expose rock in 1976 that has since become lush vegetation in 2004. The glacier has retreated so much that it is hardly visible in the 2004 photo. —Credit: National Snow and Ice Data Center (comp.). 2002, updated 2009. Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center.

Qori Kalis Glacier in 1978Glaciologist Lonnie Thompson has visited Peru’s Quelccaya Ice Cap at least 27 times to retrieve ice cores and investigate the cap's outlet glaciers. The Qori Kalis Glacier is one of several glaciers along the Qelccaya Ice Cap that is retreating. —Credit: Photograph by Lonnie G. Thompson. 1978. Qori Kalis Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center.

Qori Kalis Glacier in 2004Meltwater from the Qori Kalis Glacier in Peru has formed a large glacial lake as it steadily retreats. —Credit: Photograph by Lonnie G. Thompson. 2004. Qori Kalis Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center.

Last updated: 16 March 2020