Sunday, September 04, 2005

Two articles

Global warming threatens alpine plants (9th September 2003)


Melting glaciers are spectacular indicators of climate change, but when it comes to biodiversity in the Alps, scientists are more concerned about the fate of fragile mosses and flowers.
The effect of global warming on alpine vegetation was one of the main topics discussed at a recent climate conference in Grindelwald.
Scientist Georg Grabherr from the University of Vienna, one of the key speakers at the conference, confirmed that if global warming continued, Europe could see vegetation shifting north- and eastwards.
The conditions would be right, he said, for flora indigenous to countries bordering the Mediterranean to thrive in central Europe.
“There’s a probability that the trees and plants that are growing there could move or grow in our area,” Grabherr told swissinfo.
According to models of forest recovery after the last ice age, Grabherr said that dominant tree species moved northwards at an average rate of 200 metres a year.
Studies that he has conducted on alpine vegetation show that a shift is already occurring.
Grabherr says plants are also moving upwards in altitude, forced to flee by invading species, and ending up “pushed to the wall” on mountaintops.
“But the big question is, will southern plants manage to migrate north,” he added.

Temperature rise

Human population explosion coupled with urban development could prove to be a insurmountable barrier preventing a new northern migration.
“You reduce the capacity of plants to propagate if the habitat is already occupied or not available, as the situation is today where most habitats have been altered by human intervention,” explained Vera Markgraf of the Institute of Arctic and Alpine Research at the University of Colorado at Boulder.
Even without competition from foreign plants, alpine vegetation is threatened by a dramatic rise in temperatures and a lack of rain, as Europe experienced this summer.
“When we talk about biodiversity, we have to consider special habitats which can disappear quite quickly,” Grabherr said, referring to mosses and grasses that cling to chalky rock faces on the mountainsides above Grindelwald.
“This summer’s drought killed a lot of the grasses on the rocks where there is normally a lot of water,” he said.
The purple mountain saxifrage could die from “overheating” he said, adding that it would be a “curious” event in the “cold climate of the Alps”.

Preservation and protection

Markgraf said efforts to preserve or protect endangered alpine habits could prove futile.
“I don’t think we can tell conservationists where they should protect areas or plant trees because we can’t predict what will happen in climate terms and where habitats might be,” she said.
But according to Martin Beniston, the director of the geography unit at the University of Fribourg, progress is being made in predicting the effects of climate change.
“We’re moving ahead with further understanding of very complex interactions between climate, climatic change and the alpine environment,” he told swissinfo.
“Because the alpine region is so heavily populated there will be impacts on economic activities, so any further understanding of the way the environment will change in coming decades will help us, perhaps, to adapt to these changes,” he said.
“I think the summer we have just lived through is a little bit of the shape of things to come.”

swissinfo, Dale Bechtel in Grindelwald


Swiss glaciers continue to melt (10th January 2003)


Switzerland’s glaciers are continuing to shrink – in some cases at an alarming rate – according to the Glacier Monitoring Service. Some 121 glaciers are regularly analysed, and almost all of the 64 scrutinised over the 2001/02 period were found to be receding.
Of the 64 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.

"Old" snow

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.

Climate change

Nevertheless, Hoelzle says the long-term trend is clear: Switzerland’s 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.

Human activity

"It is certain that the climate is changing, and getting warmer," he said. "What's more difficult to say is whether human activity is responsible. But there is very 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."

Consequences

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. And 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.
"The 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, with possibly very severe consequences, such as increased storms and flooding."

swissinfo with agencies


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