Glacier retreat and consequences

According to a Méteo France study published in 2005, temperature in the French Alps has increased over the last four "more than the rest of France." Indeed, as temperatures on the French territory increased 1 degree on average (against 0.6 in the world). Altitude to 1800 meters in the winter, temperatures have increased by 1 to 3 degrees.

In addition, a climatologically study of the Alps from 1958 to today, also shows that "the most recent years appear to be largely deficient" in the snow.
According to researchers at the Centre for the Study of Snow Météo-France (Grenoble), there have been these last 40 years of "snowy winters of 1975-1985 and a deficit of white gold from 1987 to 1993." (Proof is that the winter of 2011 was particularly low snow).

Glaciers are a predominant part of the Alps, and because of climate change, these people may need to disappear the next 100 years according to glaciologists from the Laboratory of Glaciology and Geophysics of the Environment (CNRS-Université Joseph Fourier, Grenoble) and the Federal Institute of Technology Zurich (ETHZ). Indeed, the glaciers are experiencing a general decline since 1850 due mainly to lower precipitation snow (especially since 1980) in 1970, the Alps Count 5 150 glaciers in an area of ​​2909 square kilometers, which already corresponds to a decrease in 35% compared to 1850. Since then, the melting of glaciers has accelerated particularly after the 2003 heat wave that began ice surface 5 to 10%.
It is estimated that the Alpine glaciers have lost half of their area since 1850 and could completely disappear within 100 years if it is based on the IPCC's global models, with a temperature rise of between 3 to 5 degrees April and September.

Modeling of the Rhone glacier showing:- Its extension in 1850 (white line)- Its size in 1973 (red line)- Its decline with a rise of 3 ° C (blue)Credit: Zemp and al

Two studies by researchers including the Laboratory of Glaciology and Geophysics of the Environment (LGGE, CNRS / Université Grenoble (1)) show that global warming has a strong impact on mountain glaciers.
The first study concerns the St Sorlin glacier (3400m). A simulation of the evolution of this glacier in the twenty-first century, carried out under the B1 scenario of the IPCC future emissions of greenhouse gases, shows that despite a relatively optimistic climate scenario (+1.8 ° C by 2100), it should have disappeared in 2060, suggesting a similar fate for all the small glaciers of the Alps located in low to medium altitude.

Mer de glace (Chamonix, France), 1850

The second study focuses on the glacier of the Dome du Goûter (Mont Blanc, 4250 m). Temperature measurements made ​​in its ice show his remarkable recent warming and up to 60 meters deep and thus the existence of an atmospheric warming at those altitudes.

                                                                             

             Mer de glace (Chamonix, France), today

A simulation carried out under different scenarios of global warming shows that the cold high-altitude glaciers could be tempered in this century. Glaciers glaciers with a temperature of -11 degrees at depth  will have their temperature increase around 0 degrees (If warming reaches the base of the hanging glaciers  it could affect their stability dangerously)

The consequences of climate change on glaciers warming will be particularly important for human activities such as Michael Zemp said "it is in the densely populated mountain regions, such as the Alps, which must consider the consequences of widespread melting of glaciers, the water cycle, water economy, tourism and natural hazards. ".

Consequences of glaciers retreat could be numerous and dangerous. Indeed their disappearance causes a local imbalance with consequences on mountain ecosystems.

•  Breaks in pockets of water : Emptying a bag can be progressive (the outlet is sometimes impossible to detect) or abrupt (usually when the hydrostatic pressure developed in the reservoir exceeds that of the surrounding ice). This pressure then expels a plug of ice in large size. When the catastrophe of Saint Gervais, in 1892, is estimated as the Tête Rousse glacier was about 30 m in diameter. The sudden release of large amounts of water can then generate a debris flow, as was the case in Tete Rousse. (Today, the threat is importance above St Gervais, the bag of water threatening the village is regularly drained despite this, it is filled with water .It is closely monitored because it is very dangerous for everyone in the Valley) .
• The formation of proglacial lakes: These lakes are formed downstream of the glacier where runoff accumulates behind a dam, usually moraine. When the glacier retreats, the ancient moraine dam plays this role. When it is destabilized, the lake drains.

                

                                      

                                    

                                                    diagrams Cemagref ( Grenoble, France)

• Serac falls sometimes cause triggering of avalanches.
• Destabilization of land sub-and peri-glacial: We may think that the glaciers concourrent stabilisation (by frost and gravity) of a number of land surface. Major melting of the glaciers and thawing of the land involved could lead to landslides. Also with a massive thawing permafrost (permanently frozen ground, especially on the shady side above 2500m) which keeps the soil in place. A large solifluction could release massive amounts of CO2 contained in the soil and cause landslides very important and dangerous for people, flora and fauna below
• Reduced water supply lakes and short lower water: In summer it is the glaciers that support the water level of lakes and water courses below. Disappearance of glaciers will cause a progressive drying up of mountain aquifers, springs, water courses, lakes. This would pose problems for water supply of population and for their electricity supply (reservoirs turbine EDF).
• Changes in climate: The enormous mass is colder than the glacier affects the local climate balance. Upsetting this balance could affect the micro-climate itself and on the ecosystem (species extinction).
• Impacts on Tourism: The history of mountain people is closely linked to their mountains and glaciers. Their predicted demise atriste and strengthens the feeling of misunderstanding with respect to policy, unable to act. More physically, one-half of summer resorts are now closed. The mountain guides are a great number of their race glacial become simple high altitude walks, in addition, many glaciers are rapidly becoming impassable due to ice and deep crevasses that outcrop.

Many scientists are currently working on climate change impact on glaciers and its consequences. It is actually a big deal in mountain areas such as the Alps.