There are even frozen rock slopes that are so unstable they can fail even before the thaw

Dr Charles Harris, Cardiff University

Most at risk are the Alps, the mountain range which covers much of Switzerland and parts of Austria, France, Germany and Italy, research has found.

This is because the Alps' steep slopes mean villages, roads and railways are built directly below altitude permafrost zones.

"If these degrade, there would be an increased frequency of slope failures, landslides and rock falls, railways blocked and rivers blocked," Dr Charles Harris told delegates at the Royal Geographical Society's annual conference in Plymouth, UK, on Wednesday.

"There are even frozen rock slopes that are so unstable they can fail even before the thaw."

Rising temperatures

Dr Harris, of Cardiff University, is co-ordinating a European Union research project called Permafrost and Climate in Europe (Pace).

"A borehole sunk above St Moritz 15 years ago shows the temperature of the ground has risen half a degree to one degree in that time," said Dr Harris. "If the temperature inside the mountain is only -2C at the moment, then it will not take long to defrost.

"The combination of ground temperatures only slightly below zero, high ice contents and steep slopes, makes mountain permafrost particularly vulnerable to changes."

Dr Harris said other boreholes had been sunk too recently to be able to assess long-term trends, which he claimed would take up to 50 years.

Areas from as far south as the Sierra Nevada in southern Spain to the peaks of northern Scandinavia had already been affected by climate change, he said.