Source: Copyright 2003, Swiss Info Date: February 23, 2003
Of the 64 glaciers studied by the Swiss Academy of Natural Sciences, 58 shrank during the monitoring period, with the worst affected the Surettagletscher in canton Graubünden contracting by 94 metres. Only four of the glaciers studied retained their mass and size, while two actually grew slightly during the period, which ended last autumn. The rate of recession differs widely from place to place, from as little as six metres for the Mont Durand glacier in canton Valais to the huge loss at the Surettagletscher.
Although worrying, scientists caution that the shrinking in size of glaciers is not automatically an indication of global warming, since they expand and contract as a matter of course.
The Mont Durand glacier, for example, was expected to shrink because old snow that had been building up on the glacier tongue had not melted for several years. The tongue of the Surettagletscher, too, was unusually far advanced and was due to recede.
More important, says glacier expert Martin Hoelzle, is a change in the overall mass of the object. Three glaciers in Switzerland lost mass in the 2001/02 monitoring period - Basòdino in Ticino, Gries in Valais and Silvretta in Graubünden. However, in preceding years they either increased in mass or remained stable thanks to heavier precipitation.
Hoelzle says it typically takes years to conclusively establish that a glacier is shrinking as a result of a warmer climate. It may take ten years before the tongue of the vast Aletsch glacier in the Bernese Oberland is affected by climate change, he adds.
Nevertheless, Hoelzle says the long-term trend is clear: Switzerlands glaciers are shrinking. "What we can say is that the glaciers, especially in the Alps, are retreating very fast. They are losing a lot of mass" he told swissinfo in an earlier interview.
Hoelzle cited the upper Grindelwald glacier in the Bernese Oberland as a prime example. "Just 15 years ago the ice came right down to the trees," he said. "Now we have to climb 980 steps up the rock to reach it. In 1850, you could see the glacier from the village of Grindelwald itself. As it crept down, it knocked over trees in its path."
Hoelzle has no doubt that climate change is responsible for the glaciers' retreat. But it is not proven that human activity is responsible for climate change.
"It is certain that the climate is changing, and getting warmer," he said. "What is more difficult to say is whether it is human activity that is the cause. But there is strong evidence to show that what we do is at least partially to blame."
So could alpine glaciers disappear altogether? Martin Hoelzle thinks this is unlikely. "Certainly a major glacier like the Aletsch glacier will survive the 21st century," he said. "Nevertheless its retreat is dramatic; it has lost around 2.5 square kilometres since 1815 - this is a huge loss of mass."
The consequences of shrinking glaciers could be severe. "In central Asia glaciers are the primary source of fresh water in summer," said Hoelzle. "If they carry on shrinking, the reduced supply could cause serious drought. Here in Switzerland they supply the hydro-electric power stations with water in summer, so here too we could have problems."
But what worries Hoelzle most is what the glaciers' retreat is telling us about the state of the world's climate. "Melting glaciers are an indicator of climate change. If they are shrinking it means the climate is changing. And that means our entire environment and weather system will change in the future, with possibly very severe consequences, such as increased storms and flooding."