These two images show the Schlegeistal, the highest and most southerly valley above Ginzling and Mayrhofen in the upper reaches of the Ziller drainage in the Austrian Tirol. Both pictures show the U-shaped valley generated by glaciation. The most striking difference between the two images is the result of the damming of the valley to make the Schlegeisstau, a reservoir that controls flooding down the valley.
The two images also show the extent to which the Schlegeis glacier receded between the early 1900s and 2002. The valley glacier of the Schlegeis can be seen coming down the valley in the upper image. In the lower image from 2002, there is no such flowing valley glacier at all. Only at the white (not gray) in the upper reaches of the image is there still any glacier. Closer examination of a more detailed image from 2002 shows terminal moraines left by the glacier when it farther down the valley in the early 1900s.
The significance of sequential images like these documenting glacial retreat is that they provide natural non-instrumental evidence of global warming. Skeptics of global warming argue that world climate is not getting warmer, and that instrumental (thermometer) records of rising temperatures are only the result of increasing temperatures at busy airports and in urban heat islands. Retreating glaciers, however, are not at airports or in urban heat islands, and so cannot by so easily dismissed by those skeptics. The retreat of these glaciers, which is widespread around the world, is independent evidence of global warming.
Acknowledgments: The image from the 1920s comes from a webpage by Jörg Robrecht, Auf der Heide 6, 33039 Nieheim - Entrup, Germany. Vielen Dank!
This page is part of the Tirol Glacier Image Collection Project.
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