Gilkey Glacier Retreat Lake Formation

February 6, 2014 2:07 pm4 comments

As glacier retreat has increased over the last 30 years, the number of new lakes formed by retreat has exploded.  Alaska is one region where this is particularly true. In 1948 the Gilkey Glacier draining the west side of the Juneau Icefield ended on an outwash plain, red dots, as shown on the USGS map based on photographs from that year.  Five kilometers up glacier of the terminus, at the junction the Gilkey Glacier was joined by the Battle and Thiel Glacier. By 1984 my third visit to the glacier,a lake had formed and grown to 1.3 km in length. One of my first of many examples where the map was no longer accurate due to glacier retreat.   Thiel and Battle Glacier still joined the Gilkey Glacier in 1984.

Gilkey_Glacier map
USGS map 1948 photograph based
gilkey 1984

1984 Landsat image

By 2013 the lake has grown to a length of 4 km.  Thiel Glacier had retreated 2600 m from its junction with Gilkey Glacier, all since 1984.   Battle Glacier has retreated 3600 m from the Gilkey Glacier and separated from Thiel Glacier since 1984. A comparison of 1984 and 2013 in Landsat image is seen below. The red arrows point to glacier junctions and the Gilkey terminus in 1984. The yellow arrow points to the 2013 glacier termini. The 2005 Google Earth view gives a more true color view of the lake, its icebergs and the barren valley between Thiel Glacier and Gilkey Glacier. By 2013 the icebergs had largely melted away.
gilkey glacier changegilkey ge 2005
Much of the retreat has been aided by calving icebergs into the lake, as seen below in a 2007 image from Scott McGee of the Juneau Icefield Research Program (JIRP). This is a typical means of enhancing retreat when a glacier terminus is in a lake, aerial image immediately below.  The Norris Glacier, Field Glacier, Patterson Glacier, Wright Glacier are other nearby examples of the same process. We could go from mountain range to mountain range and recite a list of glaciers retreating and lakes expanding. In New Zealand it would be Tasman, Murchison and Hooker Glacier. In Nepal it would be Imja, West Barun Glacier and Lumding Glacier. Gilkey Glacier still remains majestic looking down glacier from the Juneau Icefield Research Program’s Camp-18 on next to the Vaughan Lewis icefall that feeds into the Gilkey Glacier. The ogives, wave forms, on the glacier are a result of this icefall’s seasonal velocity fluctuations, bottom image. JIRP will be back in the field monitoring this glacier this summer.

gilkey terminus

Gilkey

 

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THE FORUM'S COMMENT THREAD

  • Great illustrations and pictures Mauri, thanks.

    Would the original Landsat imagery from 1972, or any earlier air photos for that matter, be useful in extending the time series backwards further?

    Have you seen this paper from December on measuring recent growth of Himalayan glacial lakes using Landsat? Any thoughts?: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0083973

  • Since we have the 1948 aerial photographs, that provides a good starting point for the time series. Gilkey Glacier is inland from the coast and was not photographed or mapped in the earlier coastal surveys like Mendenhall Glacier or Taku Glacier in the period around 1900. Here I use 1984 since I was on the glacier, the imagery was good and the lake was developing.

    I have the lakes in the Himalayas are expanding rapidly in most cases. Most are not a threat for outburst flooding, but that is the main reason behind continued updated mapping. Satellite imagery is the only way to assess most of these remote glaciers, such as Reqiang Glacier, Tibet

    • OK, thanks. Do you know what information source was used to map the location of the glaciers on the USGS topo (top image). Aerial photos again? And when was that topo published, 1950s, 15 minute series?

      Your website is a great resource by the way; people should spend some time looking at it.

  • The maps are based on 1948 aerial photographs, I believe taken by the Navy. This is for the 1950’s 15 minute series.
    All but one of the 19 main outlet glaciers of the Juneau Icefield have retreated significantly since 1984.

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  • http://ecologicallyoriented.wordpress.com/ Jim Bouldin

    Great illustrations and pictures Mauri, thanks.

    Would the original Landsat imagery from 1972, or any earlier air photos for that matter, be useful in extending the time series backwards further?

    Have you seen this paper from December on measuring recent growth of Himalayan glacial lakes using Landsat? Any thoughts?: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0083973

  • http://glacierchange.wordpress.com/ Mauri Pelto

    Since we have the 1948 aerial photographs, that provides a good starting point for the time series. Gilkey Glacier is inland from the coast and was not photographed or mapped in the earlier coastal surveys like Mendenhall Glacier or Taku Glacier in the period around 1900. Here I use 1984 since I was on the glacier, the imagery was good and the lake was developing.

    I have the lakes in the Himalayas are expanding rapidly in most cases. Most are not a threat for outburst flooding, but that is the main reason behind continued updated mapping. Satellite imagery is the only way to assess most of these remote glaciers, such as Reqiang Glacier, Tibet

    • http://ecologicallyoriented.wordpress.com/ Jim Bouldin

      OK, thanks. Do you know what information source was used to map the location of the glaciers on the USGS topo (top image). Aerial photos again? And when was that topo published, 1950s, 15 minute series?

      Your website is a great resource by the way; people should spend some time looking at it.

  • http://glacierchange.wordpress.com/ Mauri Pelto

    The maps are based on 1948 aerial photographs, I believe taken by the Navy. This is for the 1950’s 15 minute series.
    All but one of the 19 main outlet glaciers of the Juneau Icefield have retreated significantly since 1984.