Swiss Alpine Glaciers and What Caused their Early Retreat I have long been fascinated by glaciers, and what their ebbs and flows tell us about climate. Here are three photos I took of the Rosenlaui Glacier (Rosenlauigletscher) in the Swiss Alps. This is the view to the southwest we had for three days earlier this month (Sept. 5-7 when clouds didn’t intervene) from our hilltop Hotel Gletscherblick (“Glacier View”) just above the tiny village of Hasliberg Goldern*, about half way between Interlaken and Lucern, Switzerland. The mountain back behind and to the right of the glacier is Rosenhorn (3689 meters). Wellhorn (3192 m) is in the right foreground and Mittlehorn (3704 m) behind it. The glacier and mountains are high above and to the southwest of the valley town of Meiringen, a train stop and the site of the Reichenbach Falls, where Arthur Conan Doyle had Moriarity seemingly kill off Sherlock Holmes. Almost all glaciers in the Swiss Alps have receded over the past century or more, and this one is no exception. The longtime proprietress of our hotel, Christine Hirsig, told me that in the 60 years she has lived there, she estimates the Rosenlauigletscher has receded about 200 meters. She says the glacier used to extend down almost to the V shape valley bottom you might barely be able to see in the photos. Others I talked to attributed the glacier retreats to global warming. But it is more complex than that. One of the longtime earth science paradoxes is why retreat of the Swiss Alp glaciers began in the mid nineteenth century, long before the current escalation of global warming documented for the past three or four decades. In fact that time is considered the end of what’s called “The Little Ice Age.” There’s no evidence of a strong decline in winter snowfall. While we were in the Swiss Alps (fortuitous timing!), a new scientific research paper was published that seems to answer that question. The paper, “End of the Little Ice Age in the Alps forced by industrial black carbon” was published in the Proceedings of the National Academy of Sciences (Sept. 17, vol. 100, no. 38, online at pnas.org/content/110/38/15216). It is also summarized in a Nature news report titled “How Soot Killed the Little Ice Age” (nature/news/how-soot-killed-the-little-ice-age-1.13650). Thomas H. Painter of the Jet Propulsion Laboratory, Georg Kaser, a glaciologist at the University of Innsbruck, and four other researchers looked at ice cores drilled into two high-altitude Swiss Alps glaciers and found that around 1860 the layers of glacial ice started to contain surprisingly large amounts of soot. Historical records indicate that by the mid 1800s airborne soot from the industrialization of Europe was thick in even some high Alpine valleys. When the researchers plugged the effect of that much black carbon soot (which absorbs more sunlight and therefore heat) in the snow and snowmelt into their models, it nicely explained the observed Alpine glacier retreat. So it appears that heavy industrial pollution of the 1800s began the long retreat of the Alpine glaciers. By the 1970s the air pollution had greatly diminished, but then the effects of greenhouse gas global warming took over. --Ken Frazier
Posted on: Thu, 26 Sep 2013 00:30:50 +0000
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