Glacier Types: Retreating

Glaciers retreat when their 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, 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.

Historic photograph of the Holgate and Little Holgate Glaciers, Alaska, 1909The Holgate and Little Holgate Glaciers terminated in Aialik Bay when this photograph was taken in 1909. —Credit: Photograph by Ulysses Sherman Grant. 1909. Holgate Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media

Photograph of the Holgate and Little Holgate Glaciers, Alaska, 2004Both the Holgate and Little Holgate Glaciers have retreated enough over the past 100 years that they are no longer tidewater glaciers. —Credit: Photograph by Bruce Molnia. 2004. Holgate Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media

Photograph of the Qori Kalis Glacier, Peru, 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. Digital media.

Photograph of the Qori Kalis Glacier, Peru, 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. Digital media.