Friday, January 06, 2017

Alaska's Shrinking Glaciers


Nearly all of North America's glaciers are in retreat. The rate of retreat has increased rapidly over the last few decades and overall each decade sees greater rates of retreat than the preceding one. The National Park Traveler has released an interactive story map, Glaciers in Alaska's National Parks: Monitoring Change, which examines the loss of Alaska's shrinking glaciers.

The map uses satellite imagery to show the modern reach of each of the featured glaciers. Orange overlays are used on the map to show the glacier's historic extent. U.S. Geological Survey topographic maps were used to determine the glaciers' extent in the mid-20th century. The historical extent of the glaciers is then be compared to the extent of the glaciers in the 21st Century, as calculated from the most recent satellite imagery.


Alaska Ice: Documenting Glaciers on the Move is another Esri Story Map which uses satellite imagery and comparisons of modern & vintage photographs to document Alaska's shrinking glaciers.

The main focus of the map is the U.S. Geological Survey's Repeat Photography initiative. USGS has been comparing modern photographs of Alaskan glaciers with historical photos, both with the same field of view. The photographs are compared to document and understand the changes to glaciers resulting from the changing climate.

The Alaska Ice story map visits 14 glaciers in the U.S. state. Each glacier can be viewed on a satellite map and a modern and historical photograph of each glacier is compared in the map sidebar. Of the 14 mapped Alaskan glaciers only two are still advancing.


Timelapse - aerial imagery of the Mendenhall Glacier in 1991 & 2012

Another interesting way to examine the loss of glaciers is with Google Timelapse. Timelapse allows you to compare aerial imagery over time for any location on Earth. You can therefore enter the name of any glacier into Timelapse and observe the effects of global warming for yourself.

Timelapse provides links to the Shirase Glacier and the Columbia Glacier but you can use the search box to locate any glacier. You can therefore use Timelapse to search for any of Alaska's glaciers and observe the highlighted loss of each glacier for yourself, using Timelapse's historical aerial imagery.
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