Alpine Glaciers

Glaciers are a defining element of high Alpine environments. Early visitors of the European Alps were stunned by the mighty ice tongues which advanced deep into the valleys. The beauty of the chaotic puzzle of icy towers, deep crevasses and white snow in the high summit regions soon attracted curious travellers from far away. For the local people alpine glaciers were at best a supplier of much wanted cooling ice (long before the invention of the refrigerator) and at worst a continuous thread of much feared natural disasters such as flooding caused by the outbreak of glacier lakes.

Today glaciers belong to the most visited attractions of the Alps and millions of visitors are stunned by their amazing beauty and the grandeur of the eternal ice in the midst of the summer.

By definition glaciers are formed by the natural accumulation of snow. Over time this snow is transformed by gravitational pressure and melt-frost cycles to dense ice. Glacial ice itself is by no means stable. It is moving and changing continuously caused by gravitational pull, i.e. glacier ice moves downhill like a water river albeit at a much lower speed. In the European Alps the moving speed of a glacier is measured in mere centimetres per days. Typically the ice of an alpine glacier moves about 10-50m a year. The move of the ice leads to friction which in return results in deep cracks called crevasses or even in entire fractured zones full of so called seracs (ice towers).

Every glacier does have two distinct areas. The area where the annual snow fall does not melt completely is called the accumulation zone, whereas the area where more snow melts than what has been accumulated during the winter months is called the ablation zone. The border line between these two areas is called the equilibrium line indicating that annual accumulation minus ablation equals to zero. Usually the equilibrium line is the same as the snow line of a glacier (below the snowline there is ice on the surface whereas above the snowline the glacier is covered by snow). The equilibrium line changes annually due to the changing weather conditions. In the European Alps the average elevation of the equilibrium line varies between 3500m in the dry regions of the inner Alps and about 2700m in the wet regions at the fringes of the Alps.

Alpine glaciers usually originate in a high mountain bowl at the head of a valley. These bowls are called cirques. Big alpine glaciers such as the Aletsch glacier in the Bernese Oberland or the Mer de Glace in Chamonix/Mont Blanc are fed by a whole system of cirque glaciers and head out into big alpine valleys flanked by steep walls. Such large glaciers can advance quite far below the snowline and even move below the tree line!

Alpine glaciers have been advanced and retreated several times over the last couple of hundred years. The last ‘ice age’ with general advancing glaciers was in the middle of the 19^th century. The stunning historical drawings and photographs showing climbing travellers scrambling through chaotic ensembles of wild seracs are all from this time period.

Since then all Alpine glaciers have been retreating with only short interruptions mainly around 1900-1920 and 1970-1980. Thus, the glaciers have been loosing length and ice mass significantly.

Recently the retreat of Alpine glaciers has been increasing dramatically with some glaciers losing over 100m of their length per year. The warmer temperatures of the last two decades resulted in a dramatic increase of the average snowline. Thus, the high alpine environment is changing rapidly with observable changes even within a relatively short time period. Melting glaciers and melting ice faces result in increasing natural hazards such as stone-fall which are dangerous for mountaineers. The steep slopes of fresh moraines unprotected by any vegetation are also quite vulnerable to debris avalanches or landslides.

According to some scientists which have studied extensively the expected consequences of climate change a large number of Alpine glaciers will disappear completely over the course of the next five or six decades. Naturally, this holds true for the smaller glaciers at a relatively low elevation (around 3000m). Even a minor increase of the snowline (e.g. from 3000m to 3100m) might result in a loss of the total accumulation region of such smaller glaciers. But even the large, still mighty glaciers of the much higher Alps in France and Switzerland will change their appearance dramatically. Their glacier tongues will retreat to far higher regions than today only leaving back a zone of rocky moraines as remnants.

Today there are still some 5000 Alpine glaciers registered in the European Alps totalling an area of about 2.900 square kilometers (or 1.100 square miles). However, recent studies by glaciologists at the University of Zurich conclude that if climate change accelerates during the next decades a good portion (up to 80 %) of these glaciers are destined to disappear.