Permafrost is one of the main components of the Earth’s cryosphere, which is a word indicating all the ice existing on Earth. It is defined as “any subsurface material which remains at or below a temperature of 0°C for at least two consecutive years” and mainly occurs in high-latitude areas of the northern hemisphere (look at its distribution map here).
Permafrost may also exist at high altitude areas of the mid- and low-latitudes, such as the Alps
A soil containing permafrost is usually characterized by a relevant amount of ice, which can be mixed with the mineral component (gravel, sand, silt) or can form lenses and layers of various dimensions. Steep bedrock slopes (rockwalls) in permafrost conditions may have varying amount of ice in their fractures. Similar to the other components of the alpine cryosphere permafrost is threatened by climate warming, which can change its thermal characteristics and, ultimately, can cause its complete disappearance.Permafrost is widespread on the Ortles massif, where it especially affects the rock faces and the ice-free areas around the glaciers. The presence of permafrost in the Ortles area is indicated by several permafrost-related landforms (mainly rock glaciers) which are located on all its mountainsides.The warming of permafrost and the melting of the ice within it can cause natural hazards because rock walls and debris slopes become more unstable.
In the Ortles area, for example, a large rockfall involving about 3 million m3 of rock occurred on the southern flank of Cima Thurwieser on 18 September, 2004. Catastrophic events like this are increasing in the Alps in recent decades and are partially attributed to the permafrost degradation.
The Ortles massif is therefore an exceptional site to study how climate change is affecting high-altitude permafrost in the Eastern Alps and to observe possible signals of degradation. The investigations focus on the measurement of the surface and subsurface temperature of several sites located around the Ortles summit both on nearly flat, debris-covered areas and on steep or nearly vertical rockwalls. The measurements are performed using thermistor probes and data loggers which allow us to continuously record the ground temperatures under a thin layer of debris and, as regards the rockwalls, at three different depths (10, 30, 55 cm).
These measurements will allow us to observe the relationships between the ground temperature and the major climatic parameters, such as air temperature, solar radiation, and snow cover. In addition, we are studying the inner thermal regime and the thermal conditions at the ice-rock interface of the Alto dell’Ortles and Hintergrat glaciers, in order to understand if permafrost is present under the glacier ice. On the Alto dell’Ortles glacier the ice temperatures are measured by two thermistor chains lowered in one of the boreholes drilled down to the bedrock during fall 2011. On the Hintergrat glacier, which is a miniature ice cap located on the ridge with the same name, we drilled a borehole about 9 m deep using a steam ice drill. The borehole was then equipped with a thermistor chain.