By Ray Smith, LUCERNE, Switzerland, Inter Press Service, Jul 22, 2011
LUCERNE, Switzerland, Jul 22, 2011 (IPS) - 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 metres.
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.
Project director David Volken says that between 1996 and 2006, 0.9 billion cubic metres of water have
melted from the glaciers yearly. He expects that until 2050, runoff from glaciers will increase, but then
rapidly drop towards the end of the century.
"Because of the warming climate, snow melt will happen about a month earlier and rainfall will decrease
10 to 15 percent in summer," Volken adds. As a consequence, the rivers' runoff regime will change, he
predicts. "There'll be more runoff in winter and less in summer. During hot summers, less water will be
available in the future," the hydrologist warns.
Matthias Huss of the University of Fribourg also stresses that the current picture is deceptive. "Due to
climate change, we currently get more water from the glaciers than normally, as they're melting. At first
glance it looks like there's no problem," he says. But Huss warns that soon the picture will change and
the remaining glaciers won't be able to provide enough water during the summer months.
Huss' glacier models are linked to specific climate scenarios. Diverging global warming estimates
therefore affect prognoses regarding glacier shrinkage significantly.
The glaciologist admits that there are large uncertainties. "However," he says, "what's for sure is that
glaciers will shrink massively. Even in an unlikely best-case climate scenario, glaciers will lose more
than 70 percent of their size until the end of the century." And in the worst case? "There wouldn't be
any glaciers any more at all."
Taking different glacier retreat scenarios into account, Huss estimates that currently glacierised basins
might contribute 55 to 85 percent less water to stream flow runoff by the end of the 21st century. "Even
if the climate could be stabilised at the current level," the glaciologist argues, "we'd witness drastic
glacier retreat and their storage ability would either drop extremely or be lost totally."
As glacier shrinkage seems unstoppable, mankind will be forced to adapt to the new situation. Water
shortages may occur more often and economic consequences may be harsh, the study warns. Especially
the agricultural sector will face serious challenges, and communities may struggle to keep up drinking
water supply.
The FOEN's Thomas Volken says that in the agricultural sector, water consumption efficiency has to be
stepped up. He adds that adjustments in the cultivation of agricultural surface are inevitable, too.
As regards drinking water supply, Volken suggests its optimisation through regional integration and
new strategies, such as linking drinking water networks to at least two independent resources. As
additional measures, the hydrologist mentions the construction of additional dams in the mountains or
systematic ground water accumulation.
Original article
