Global warming & glacial retreat

It has been well documented that following a cycle of hot summers and mild winters, European glaciers are slowly retreating. Whether this is a result of predictable climate trend or increased human impact on global climate remains to be seen.

How do glaciers react to climate change?
The volume of ice in a glacier, its corresponding surface area, its thickness, and its length are determined by the balance between inputs (accumulation of snow and ice) and outputs (melting and calving). As climate changes, the balance between these inputs and outputs can be disrupted ultimately affecting the thickness and advancement, or retreat of the glacier. Temperature, precipitation, humidity, wind speed and other key factors such as the slope and the reflectivity of the glacier surface all further affect the balance between inputs and outputs. Most glaciers in the world are more sensitive to temperature than to other climatic factors. Many ski resorts are now suffering from glacial melting including; Tignes, Chamonix, Les deux Alpes and Alpe D'Huez.

Glacial Shrinkage
It has been reported that there has been 20 metres of shrinkage in the glacier at the foot of the Signal piste in Alpe d’Huez (2800 metres) over the past twenty years, with the most noticable progession during the last five years. Until the summer of 2006 there had not been an huge impact on the summer skiing with the Alpe d’Huez glacier opening but the position has recently changed.

Probably one of the most visual example of 'Glacier Meltdown' is in Chamonix, France. Chamonix is home to some of the most well known glaciers namely, Mer de Glace (sea of ice), Glacier d'Argentiere and the Glacier des Bossons. All are pretty spectacular pieces of scenery however, statistics clearly show all have been steadily receding since the early part of this century. Take for example the Glacier des Bossons. A hot, dry summer during 1995 saw 'glacier melt' accelerate significantly, loosing some twenty meters in length and volume.

Glacier des Bosson in 1928	Glacier des Bosson in 1952
Glacier des Bosson in 1983	Glacier des Bosson in 1995

Whilst this was worrying, the 1995 receding position of the glacier was actually comparable to that of 1952, where a natural period of glacial regression created a similar effect. Christian Vincent of the Glacial & Geological Environmental Laboratory in Grenoble has been studying the effects of the worldwide climate change and specifically notes the impact on the Alps. In the past 150 years the Alps have seen glaciers retreating by some 30%, with a marked acceleration since the early 1980s. He has however previously commented that some of the glacier retreat scenarios put forward by so called 'experts' have been 'largely overestimated', also saying that glacier retreat is not a good indicator of global warming because it depends on various factors. He suggests that losses from French glaciers can be accounted for by a 0.75ºC rise in average temperatures.

Under a constant climate, when a glacier melts its surface reduces. The front of the glacier retreats gaining alititude until it reaches a balance point where it can once again begin to develop. The Glacier des Bosson may well be experiencing a period of regression and might reach the balance point where it can begin to redevelop. Curiously, at the start of this century religious processions were organised in an attempt to to push back this glacier because it threatened the village of Chamonix.

Glaciers rely on snowfall whether in summer or winter and staff in resorts work hard to preserve snow during the winter but weather and resort latitude are key factors in glacial creation and stability. For example, the Sarannes mass located below Alpe d’Huez in the Southern Alps appears to be suffering greatest from glacial recession in comparison to glaciers found in the Northern Alps. High global temperatures have seen the glacier in Sarannes mass recede significantly over the past few years. There remains a small glacier about a square kilometre, and 70 metres in depth, at an altitude of 2800 ­ 3200 metres, not too disimilar in height to the Grand Mott (3456m at the highest point). The last two decades has seen this area be the victim of some of the poorest winter snowfalls. December 1988 and 1989 saw a distinct lack of snow in the area which in addition to affecting the glacier development, created hugh problems for those replying on the snow for income. It is anticipated that this glacier will have disappeared by 2050.

The imposing questions that arise from much of the above feature are; 'is global warming responsible, if so, how long will the planetary warming continue or even accelerate', and 'what price will our glaciers pay during this acceleration?' As many alpine resorts depend on the winter and its seasoned activities to bring them income, it is becoming more important for them to broaden their activities in preparation for these changes future climate conditions may bring.

Pistehors.com recently commented that 2005 is shaping up to be the hottest year on record. According to sources the average temperatures that have been taken from up to 7,200 weather stations indicate that 2005 is 0.4ºC hotter that the previous hottest year in 1998.


Photo Credits | Glacier des Bossons and Deutche Welle