“We can hope to keep some parts of the Mer de Glace”

Global warming will cause at least half of the world’s glaciers to disappear by the end of the century, according to a study published this Thursday in the journal Science. Etienne Berthier, one of its authors, details the results for the Alps.

This is an unconditional conclusion: the vast majority of alpine glaciers will disappear before 2100. That’s the conclusion of a study published this Thursday, January 5, in the American Journal. Science and attempts to describe the effects of rising temperatures on melting glaciers. Etienne Berthier, a glaciologist at the Laboratory for Spatial Geophysics and Oceanographic Research (LAGOS) in Toulouse and CNRS research director, is one of the co-authors. He returns to the French 3 Alps in this new lighting.

What was your method? How is it new?
We used a mathematical model to represent the response of glaciers to future climate change. New observations were used to calibrate the model compared to previous studies, making it as realistic as possible. In particular, satellite observations in the last 20 years. This is a period of accelerated mass loss, and the model takes this acceleration into account. We have added two modules to include two mechanisms that have not been considered so far. The first is the birth of an iceberg – that is, glaciers growing in oceans and lakes will break off at their fronts and release blocks of ice, which causes mass losses from glaciers. The second module states that glacier tongues like the Mer de Glace tongues are becoming more and more polluted, covered with debris.

Research projects, at best, 49% The world’s glaciers are in danger of disappearing by the end of the century. And the Alps?
Our forecasts show that if the temperature increase is not controlled and reaches 4°C on a global scale, all the glaciers of the Alpine arc would disappear. It will remain the best 1% glaciers. On the other hand, if we manage to limit the rise in temperature 1.5°C A small part of the Alpine glaciers is protected by strict restrictions on greenhouse gas emissions, i.e. 15%. It shows that they are very sensitive, very sensitive and already deeply imbalanced with the climate. This explains these massive losses regardless of the future scenario.

Which glaciers survive best?
The rare glaciers in the Alps that may persist beyond 2100 are the highest-altitude glaciers, if the temperature increase is not too great. Typically, we can expect to retain some parts of the Mer de Glace and pieces of glaciers around the summit of Mont Blanc or Mont Rose. So, indeed, the highest peaks of the Alpine arc above 4000 m. Below these heights, all glaciers are doomed.

Is it still possible to stop this phenomenon?
The only one to protect some glaciers in the Alps choice-c1.5 and being able to follow more favorable scenarios with limited temperature rise 2°C. Then there are initiatives to protect some parts of the glacier locally at the level of ski resorts. However, this is a somewhat fanciful approach that applies to very small areas, and we cannot protect entire mountain range-scale glaciers by any means.

Yes does What do you think about these results?
We are a bit like a doctor at his patient’s bedside. We’re here to study glaciers like pros. We cannot talk about the results we see on our screens every day. The difference from the doctor is that, unfortunately, we cannot treat him. We can simply send messages to society to make people understand the importance of reducing our greenhouse gas emissions, keeping temperatures at a level to protect the few glaciers that can be protected, especially high-altitude glaciers or polar regions. But it is true that for us it is powerful and a little painful to see mountain ranges like the Pyrenees, in 10-20 years there will be no more glaciers. Therefore, I will not be able to show them to my children and My relatives in the very near future.