•  lucerne, switzerland
• Monday, July 25, 2011
• Inter Press Service

Future glacier retreat in the Alps could affect the hydrology of large streams more strongly than previously assumed, a new study shows. Water shortages in summer could become more frequent.

Even though their ice is called 'eternal', many alpine glaciers' lives may come to an end within this century. For 150 years, most of them have been more or less constantly retreating, and since the eighties, their shrinkage has visibly increased.

The Furka Pass in central Switzerland has long been awaiting its visitors with a special attraction. Just below the highest point of the pass, tourists may enter an ice grotto dug into the Rhone glacier to discover glacier life from the inside. Each year however, the grotto's entry can be found a few metres further downhill. Long-term measurements reveal that from 1879 to 2010, the Rhone glacier has lost 1266 metres of its original length.

The Swiss Alps are often called 'Europe's water tower'. Nearly 60 billion cubic metres of water are stored in its glaciers. Matthias Huss, glaciologist and senior lecturer at the Department of Geosciences at the University of Fribourg explains that glaciers fulfil a balancing function: 'They release water exactly when we need it, while storing it in periods when we need it less.'

In other words, glaciers store water during the cold and wet winter months. From May to September, snow and ice melt on the glacier surface and provide the water that is dearly needed during the hot and dry season. That same mechanism also balances year-to-year variations: in colder, wetter years glaciers accumulate water that is released in relatively hot and dry summers like in 2003.

The threat posed to alpine glaciers' essential contribution has long been recognised. However, a new study presented by Matthias Huss in the scientific journal 'Water Resources Research' found that the proportion of glacier water running down major European streams is larger than previously assumed.

'I have compared water runoff data from glaciers with actual runoff at gauges along the entire length of four major streams originating in the Swiss Alps,' explains the glaciologist. His study is based on measurements along the Rhine, Rhone, Po and Danube rivers.

The comparison allowed Huss to determine the relative share of glacier water running down those streams. 'Consequently, I was able to quantify how much the runoff of those streams could decrease in case the glaciers' contributions are entirely lost,' he says.

One of the streams observed by Huss is the Rhone. Originating in the Upper Valais in Switzerland, the river passes through the Rhone Valley and Lake Geneva to France, finally reaching the Mediterranean Sea at the Camargue Delta near Arles. The Rhone's length is 813 kilometres, its drainage basin measures about 100,000 square kilometres.

In August, snowmelt runoff from non-glacierized regions of the catchment is small, while bare ice melt is most important. According to Huss's calculations, the 100-year average glacier contribution to the Rhone accounted for 25 percent of the total runoff. In August 2003, the share deriving from glacier storage change rose to 40 percent; a proportion not to be ignored during that extremely hot and dry summer.

At Switzerland's Federal Office for the Environment (FOEN), researchers are well prepared to deal with the consequences of climate change for the Swiss water household. The FOEN recently started 'Project CCHydro'. The project name stands for climate change and hydrology in Switzerland. Based on current climate scenarios, the project aims to provide detailed forecasts on the hydrological cycle and runoffs in Switzerland for the coming decades.

© Inter Press Service (2011) — All Rights Reserved. Original source: Inter Press Service

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