Last summer, in one of
the largest rescues in mountaineering history, more than 70 climbers were pulled
from the slopes of the Matterhorn in the Swiss Alps. Climbers became stranded
when the mountain literally began to crumble under their feet. Now, researchers
are blaming record-breaking summer temperatures in 2003 for the destabilization
of the Alps.
Geologist Stephan Gruber installs a data-logger to measure permafrost thaw in
the Alps. Increased rock falls in the Alps may be an unexpected consequence
of climate change. Courtesy Stephan Gruber/Marco Peter.
In the July Geophysical Research Letters, Stephan Gruber of the University
of Zurich and others link rock falls to the distribution of permafrost thaw.
Permafrost is soil or rock that remains frozen all year long and can include
vertical rock faces in alpine environments. Frozen water in the cracks and crevices
of rock faces acts like glue, holding rocks together. When the ice melts, the
rocks become extremely unstable — even more so than if the rocks were completely
dry, says Michael Davies, a civil engineer at the University of Dundee in Scotland,
who was not involved in the study.
From 2001 to 2002, Gruber’s team measured temperature and heat flux in
rock faces at different elevations and with different aspects (for example,
north-facing versus south-facing walls). Using the data, they verified models
predicting where permafrost thaw was likely to be the greatest. Then, in 2003,
unbeknownst to the researchers, Switzerland experienced one of the hottest summers
in the past century, Gruber says. And the exceptional rock fall that summer
correlated well with the researchers’ predictions for permafrost thaw —
helping to verify their model.
Gruber says that increased awareness after the rock falls of 2003 refocused
attention on the danger of permafrost degradation. “It changed people’s
perspective,” he says. “Now companies are beginning to look where
rock falls could affect infrastructure and tourism.”
Gruber and colleagues’ model may play a role in increased safety precautions.
“This research will help us tell where and when a fall will take place,”
Davies says. “If we know where rock falls are likely and someone is installing
a cable car, for instance, we can put rock bolts into the wall before construction
begins.”
The real danger, Gruber says, may be a changing climate with overall warmer
temperatures and increased seasonal variability. With large spikes in temperature
on top of already warm conditions, Gruber says, permafrost that may have been
frozen for many hundreds or even thousands of years, such as some shaded, north-facing
alpine rock faces, is now vulnerable to thaw.
Jay Chapman
Geotimes intern
Back to top
 |
Geotimes Home | AGI Home | Information Services | Geoscience Education | Public Policy | Programs | Publications | Careers  |