Look Out Below

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For 10 days earlier this month residents in the tiny Italian Alpine village of Macugnaga (pop. 700) were under threat. A giant lake had formed atop a glacier on Monte Rosa, and authorities worried that the water would burst its banks — or worse, that the glacier itself would become dislodged, sending a river of ice, mud, rock and debris crashing down the mountainside and into Macugnaga situated below. Disaster was averted thanks to cooler temperatures and frantic efforts to pump water out of the lake.

But for Andreas Kääb, a glaciologist at the University of Zurich, the Macugnaga incident is both a fascinating case study and an ominous sign of things to come. "Macugnaga presents most of the world's glacial hazards — ice avalanches, rockfalls, floods and a glacier advance that is very fast," he says. Scientists now believe that these hazards are occurring more frequently due to global warming, and that increased tourism has made mountain communities more vulnerable. Swiss studies indicate that Alpine glaciers have receded between 5% and 40% since the early 1970s. At the same time, previously remote mountain areas have been developed for skiing and other forms of tourism. Many experts are now concerned that as the glaciers recede, the natural risks associated with them are increasing. "Over the last 20 years, we've seen higher temperatures and more melting," says François Valla, a glacier expert with Grenoble's Cemagref research center. "We're seeing new lakes forming everywhere."

To deal with the potential threats, Valla has launched Glaciorisk, a six-country scientific project that aims to improve our understanding of glacier hazards and establish a database that will include "problem glaciers." Valla estimates there are probably 100 glaciers in the Alps alone that "could cause worry and create victims."

In Macugnaga, scientists are still struggling to explain why the glacier is sliding down the mountainside so fast. All that melting water may be a factor, but the movement may also have something to do with the glacier itself — the distribution of its ice mass and its underground water pressure. Regardless of what is behind the Macugnaga incident, most scientists agree that the state of glaciers is an indication of the overall health of the planet. "It's hard to say how much is due to natural forces and how much human activity is to blame," says Luca Mercalli, an Italian climatologist monitoring Macugnaga. "But melting glaciers are a symptom, a warning that we need to pay attention."