Photographer William O. Field
(photographed on 13 August 1941) (National Snow and Ice Data Center, Boulder, Colorado, website nsidc.org/data/glacier_photo)
Photographer Bruce F. Molnia
(photographed on 31 August 2004) (National Snow and Ice Data Center, Boulder, Colorado, Website: nsidc.org/data/glacier_photo)
The National Snow and Ice Data Center, based at the University of Colorado in Boulder, maintains an archival collection of photographs for the American Geographical Society. The photographs date from the 1880s to the present, and they document a broad range of cold climate conditions such as glaciers, ice shelves, blizzards, avalanches, and sea ice cover. The Long-Term Change Photograph Pairs Special Collection is a fine source of historical and contemporary photographs depicting evidence of climate change in the United States and Canada. The 1941 photograph of Muir Glacier (Alaska) is a black-and-white view of glacial ice filling a U-shaped valley. The direction of flow of the glacier is evident in the alternating light and dark bands or concentric curves of ice dominating the scene. One cannot discern whether the short-term trend in this valley is one of glacial advance or glacial retreat, but the presence of ice essentially at the camera's base indicates that this glacier is well established at the vantage point chosen. The denuded left foreground indicates that at some time in the recent geological past these exposed bedrock surfaces had been scoured by the glacier. In the distance, thin slivers of mountain top emerge above the glacial ice. They are dotted with their own pockets of snow and glacial ice. This is a dynamic natural system, best evidenced by the irregular surface of the ice flow.
A 2004 view of Muir Glacier from the same vantage point gives a far different picture. The denuded landscapes of 1941 now are covered with deciduous and coniferous tree growth. The steeper mountain slopes consist of bald bedrock, while more gradual slopes, formerly covered by glacial ice, are heavily vegetated. The retreating glacier is visible in the far distance, its outer edge recessed thousands of feet from its former position. A glacial lake dominates this present day view. Its surface is located some hundreds of feet below the glacial ice surface of 1941. Scattered blocks of ice float on the lake in the foreground. The mountain peaks in the distance now appear much more massive. Their glaciers are considerably reduced in size, or the glaciers have withdrawn completely from their former cirque localities.
In recent weeks, former Vice-President Al Gore has released a film about global warming and a companion book,
An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It
. In the book, Gore uses paired photographs of glaciers from the United States, Patagonia, Argentina, Peru, Switzerland, and Italy, as seen in the late nineteenth century and mid-twentieth century, and seen again today. For example, Boulder Glacier in Glacier National Park (Montana) is pictured in 1932 and from the same vantage point in 1988. His collection of photographs from North America, South America, Europe, Africa, and Asia documents the substantial loss of glaciers in many parts of the world. One of the most dramatic images in
An Inconvenient Truth
is the "wastage of Columbia Glacier, Prince William Sound," Alaska evident in pictures framing the last twenty-five years. The consensus opinion that has emerged from the scientific community about the accuracy of
An Inconvenient Truth
is that Al Gore has got his facts right. His highly personal book and film are important contributions to the popular environmental literature and undoubtedly will serve as useful educational tools.