Why did Mont Blanc lose two meters in altitude?

The summit of Mont Blanc has lost two meters in height according to the last official measurement revealed on Thursday October 5. How can this trend be explained? the decline observed for several years?

The roof of Europe no longer peaks at 4,810 meters. In recent years, Mont Blanc has lost a few meters according to the most recent measurements, including those dated September 2023 and revealed this Thursday, October 5. The Alpine mountain is today 4,805.59 meters high, so it has fallen in height. of 2.22 meters in two years indicate the expert surveyors from Haute-Savoie responsible for the measurements.

The height of Mont Blanc has been measured every two years since 2001 and to know the exact size of the European giant, surveyors have no other choice than to climb the alpine mountain. On each expedition, around twenty altitude experts take measurements over several days at the summit of Mont Blanc. In 2021, the roof of the Alps peaked at 4,807.81 meters was already high. one meter less compared to the previous readings of 2017, those of 2019 having remained secret because they were considered abnormally low and not very representative.

The new official measurement from Haute-Savoie surveyors therefore confirms that Mont Blanc is sinking over the years. A trend observed since 2007, a record year where the summit of the mountain culminated at 4,810.90 meters. But experts are not worried about these measures. The size of Mont Blanc only varies by a few meters every two years and these variations are partly due to meteorological conditions, in particular the rainfall which has been reduced. quite low during the summer; 2023. These measures therefore do not assume a continuous and irreversible decline. "Mont Blanc could very well be much higher in two years" when the next measurement will be carried out thus affirmed Jean des Garets, the president of the departmental chamber of surveyors of Haute-Savoie during a press point in Paris. Chamonix. The mountain has already been restored. has gained several meters in height in the past, such as between 2003 and 2007, going from 4,808 to 4,808 meters. 4,810 meters.

The decline of Mont-Blanc symptomatic of global warming?

Since 2001 and the start of measurements of Mont Blanc, the altitude of the summit of the mountain has oscillated and the surveyors explain it: the rocky peak of the Alpine summit culminates at 4,792 meters. The remaining few meters depend on the thickness of the layer of “perennial snow”. which forms a snowdrift and varies "depending on the altitude winds and precipitation". The altitude of Mont Blanc therefore changes throughout the seasons and the summit is always higher at the end of summer. only during winter or spring when the wind removes the last meters of snow.

The surveyors-experts from Haute-Savoie, including Denis Borel, had already done this. called in 2021 'do not draw hasty conclusions on measures that have been taken' carried out only since 2001" on the altitude of Mont Blanc. They leave it to climatologists to assess the consequences of global warming on the altitude of the roof of the Alps. It's at the latter that it is up to “to put forward all the hypotheses to explain this phenomenon”. Because, unfortunately, climate change has shown itself to be dangerous. its first effects on European glaciers which are more vulnerable to the rise in temperatures due to their low altitude. In 2022, the glaciers of the French Alps have notably lost 5%. 7% of the remaining glacial mass according to specialists, the melting of the ice had then been reduced. judged "exceptional".