Wednesday, 31 December 2008

Accelerated recession of Swiss glaciers

Evidence has emerged that several large Swiss glaciers are in 'full' retreat. The work has been completed by the Swiss Federal Institute of Technology and suggests that the negative mass balance trend is getting steeper (see graph). Two factors primarily determine the mass balance of a glacier - winter precipitation in the form of snow, and the efficacy of summer melting. Evidence suggests that for the glaciers studied, winter snowfall has changed little. Conversely, the summer melt season has increased in length.

In the study, glaciologists determined the total volume of ice in Swiss glaciers at 74 cubic kilometres in 1999. This was determined partly by direct measurement and partly by modeling. This figure is thought to have been reduced by 13% between 1999 and the present day. There is less concern about the medium term fate of the larger glaciers such as the Aletsch (see photo) as these contain 80% of all the ice in the Swiss glaciers. Of greater concern is the short term fate of small glaciers - many of these are unlikely to survive more than a few years. Aside from the obvious impacts on landscape and tourism, many Swiss glaciers play an important role in water supply and the generation of hydro-electric power.