The media reports on “global warming” often highlight widespread glacial retreat as evidence of worldwide warming. For instance, see the quote from the Arizona Daily Star,
“As evidence of global warming’s effects, Gore shows Alaska’s rapidly retreating glaciers…”
However, in a recent trip to southeast Alaska where I revisited several glaciers that I had viewed several decades ago, it is clear that the issue is more complex than indicated by such news releases. The Margerie Glacier in the northwest corner of Glacier Bay National Park, for example, was in nearly the same place as it was 16 years ago. Southeast of the Park,, the Mendenhall Glacier near Juneau had clearly retreated since I visited yet using the display at the Visitor Center, the northern front the glacier had not changed its position significantly since 1995.
The National Park Service, in their Offical Map and Guide for Glacier National Park states that
“Glacial retreat continues today on the bay’s east and southwest sides, but on its west side, two glaciers are advancing.”
This is not the type of information that is reaching the news media. All of Alaska’s glaciers are not “rapidly retreating”.
In a search on the web, other examples of glacial advance in Alaska are presented. This includes the summaries listed below,
“Hubbard Glacier, one of the few advancing glaciers in the world, could block the entrance to Russell Fiord near Yakutat, Alaska, creating a large ice-dammed lake…. Hubbard Glacier retreated to over 1000 feet from Gilbert Point in summer 2005 and remains a considerable distance from closing. The glacier does not start its annual advance until February and USGS will reinitiate monitoring at that time. Glaciologists predict that Hubbard Glacier will again block Russell Fiord; however they cannot predict when this event may happen. Hubbard Glacier has advanced and retreated in the past and there is evidence of a previous overflow event into the Situk River. ”
A Cyberwest magazine article writes that,
“A University of Alaska Fairbanks glaciologist reported that a glacier in the central Alaska Range has surged, or advanced rapidly. The McGinnis Glacier surge was observed by Martin Truffer, associate professor of physics with UAF, who noticed that the lower portion of the glacier was covered in cracks, crevasses and ice pinnacles — evidence that the glacier recently moved forward at higher-than-normal rates. ”
A similar pattern of complexity in glacial advance and retreat has been observed outside of Alaska. A March 2005 paper by Chinn et al in Geografiska Annaler entitled “Recent Glacier Advances in Norway and New Zealand: A Comparison of their Glaciological and Meteorological Causes” has the following abstract,
“Norway and New Zealand both experienced recent glacial advances, commencing in the early 1980s and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation. In Norway, the changes are also associated with lower ablation season temperatures. In New Zealand, where the positive balances were distributed uniformly throughout the Southern Alps, the period of increased mass balance
was coincident with a change in the Interdecadal Pacific Oscillation and an associated increase in El Niño/Southern Oscillation events. In Norway, the positive balances occurred across a strong west-east gradient with no balance increases to the continental glaciers of Scandinavia. The Norwegian advances are linked to strongly positive North Atlantic Oscillation events which caused an overall increase of precipitation in the winter accumulation season and a general shift of maximum precipitation from autumn towards winter. These cases both show the influence of atmospheric circulation on
The Chinn et al paper is very informative. It provides a discussion of why we need to focus on regional climate change and variability with respect to glacial retreat and advance. The use of a global average concept (such as global warming), and the statement claiming that Alaska’s glaciers are rapidly retreating, is an erroneous oversimplification of the complex behavior of glaciers.