Satellite tv for pc picture of Mendenhall Glacier captured on August 17, 1984, by the Thematic Mapper on Landsat 5.

Satellite tv for pc picture of Mendenhall Glacier captured on July 28, 2023, by the Operational Land Imager on Landsat 8.

Mendenhall Glacier is a well-liked vacationer vacation spot close to Juneau, however every year there’s much less of it to see.

Every year, lots of of hundreds of individuals go to Mendenhall Glacier—an simply accessible glacier close to Juneau in Southeast Alaska. However every year, there’s much less and fewer of the glacier to see.

Satellite tv for pc Imagery Comparability: 1984 vs. 2023

These satellite tv for pc photographs present the glacier throughout summer time in 1984 (higher) and 2023 (decrease). Snow and ice are blue in these false-color photographs, which mix infrared and visual wavelengths to raised differentiate areas of ice, rock, and vegetation. False colour additionally permits a greater colour match between the 2 photographs that have been collected by totally different satellite tv for pc sensors. The 1984 and 2023 photographs have been acquired by the Thematic Mapper on Landsat 5 and the Operational Land Imager (OLI) on Landsat 8, respectively.

Throughout the time spanned by the picture pair, Mendenhall retreated by about 1 mile (1.6 kilometers). Within the 1984 picture, the glacier’s entrance ends on the tip of a outstanding peninsula in Mendenhall Lake. This proglacial lake collects rain and meltwater and feeds the river flowing south via the Mendenhall Valley, a suburb of Juneau. Within the 2023 picture, nevertheless, a lot of the glacier terminates on land and solely partially reaches the lake. Thinning has additionally taken a toll on the glacier in the course of the previous 4 many years, inflicting it to slender by about 2,000 toes (600 meters) on the bend closest to its entrance.

July 28, 2023

Historical past and Influence of the Glacier’s Retreat

Mendenhall Glacier began retreating within the mid-1700s following a interval of glaciation that started 3,000 years in the past. However in current many years, Alaska has been warming twice as quick as the remainder of the US, serving to to push the area’s glaciers into an particularly steep decline. The Juneau Icefield, of which Mendenhall Glacier is a component, misplaced 63 out of 1,050 small glaciers inventoried between 2005 and 2019. Throughout that very same interval, the icefield misplaced 10 % of its glacier space.

Outburst Floods and Environmental Influence

The 2023 satellite tv for pc photographs, on the prime of this web page and the wide-view above, have been acquired on July 28, one week earlier than a glacial outburst flood. Meltwater collects in a basin the place a tributary glacier as soon as joined Mendenhall on the glacier’s edge. This basin can abruptly drain, inundating the lake and river. Outburst floods have been taking place right here yearly since 2011. On August 5, 2023, gauge knowledge confirmed record-high lake ranges, producing a torrent of water that destroyed properties and displaced residents alongside the river.

{Photograph} of Mendenhall Glacier taken in July 2022.

NASA Earth Observatory photographs by Wanmei Liang, utilizing Landsat knowledge from the U.S. Geological Survey. Story by Kathryn Hansen with science overview by Christopher Shuman/UMBC/NASA GSFC.