Mont-Blanc has lost 3 meters in height since 2010, but is this necessarily due to global warming ?

A reliable database for the future generations

Measured in mid-September 2021, Mont-Blanc was 4,807.81 meters high, as announced by the Order of Expert Surveyors on Wednesday September 29. For the highest peak in Western Europe, this represents a meter less than in 2017 and more than three meters compared to 2010, according to scientists. Essential measurements that experts have been carrying out since 2001 every two years. During their somewhat perilous three-day mission, they are equipped with sensors linked to satellites in order to model the ice sheet. The goal is to provide an accurate and reliable database that can be passed on to future generations.

13 centimeters per year

In 2017, the altitude of Mont-Blanc was 4808.72 meters, down from those of previous years. It will be necessary to wait until 2019 to find that the summit was only subsiding with a measurement of 4,806.03 meters, which had not been made public. Indeed, the surveyors preferred to wait for that of 2021 to find a little more educational and scientific explanations. It was in 2010 that the summit of Mont-Blanc was at its highest, reaching 4,810.90 meters, very close to the 2001 measurements which amounted to 4,810.40 meters, according to figures from the Order of Experts. surveyors. Conclusion: the figures show a decrease in the height of the summit of an average of 13 centimeters per year, and this since 2001. However, if these figures vary from time to time, it is because the summit is “covered with a layer of ‘eternal snow’ which functions like a huge snowdrift”. This cap of ice and snow measures about 15 meters and “varies according to altitude winds and precipitation”. “The stronger the precipitation and the weaker the wind, the more snow accumulates at higher altitudes”. If the expert surveyors have established an average drop in the altitude of Mont-Blanc since 2001, they believe that we should not “draw hasty conclusions on measurements which have been carried out only since 2001 with the precision that ‘we show you today”. Difficult, at this stage, to link this “shrinkage” to the climate crisis.

Difficult to link It to the climate crisis.

“At this altitude, global warming has no impact on the size of the summit, which depends solely on snowfall and wind,” says Ludovic Ravanel, geomorphologist at the CNRS, interviewed by Le Parisien. However, he admits that the rise in temperatures could, in the long term, have an impact on the melting of the summit snow during the summer. Scientists have already established that the Alpine arc is particularly affected by the climate crisis. One of its most emblematic glaciers, the Mer de Glace, has retreated about two kilometers since 1850. The glacier, which is in the Mont-Blanc massif, has also lost 120 meters in thickness during the last century.