2023-10-05 15:15:00
Mont Blanc, the summit of Western Europe on the Franco-Italian border, was measured last September at 4,805.59 meters, or 2.22 meters less than in 2021, a team of expert surveyors announced on Thursday. French, leaving it to scientists to “explain this phenomenon”.
Armed with cutting-edge tools and equipped for the first time with a drone, around twenty people divided into eight ropes climbed the white giant in mid-September in order to carry out point-by-point surveys for several days, as they do every two years since 2001.
This is the 12th edition of this operation which aims in particular to model the ice cap and collect scientific data on the impact of climate change on the Alpine mountains, specify the participants in this initiative, launched in 2001 by the chamber. expert surveyors from Haute-Savoie — a department bordering Italy in particular, which today brings together several partners.
“I am announcing to you that this year the measurement of Mont Blanc was 4805.59 meters. We have a variation of 2.22 meters” compared to the previous measurement of 2021, indicated Jean des Garets, president of the chamber during a press point in Chamonix.
“It is now up to climatologists, glaciologists and other scientists to exploit all the data collected and to put forward all the hypotheses to explain this phenomenon,” conclude the experts, emphasizing that their own role is limited to “accumulating data for generations future”.
According to Mr. des Garets, the strong difference compared to 2021 should be “put into perspective”.
“Have we ever had such a strong variation? The answer is yes”, he noted, specifying that it could reflect summer rainfall variations and calling not to “use (the measure) to tell anything”.
“Mont Blanc could very well be much higher in two years,” during the next measurement, he stressed.
Dune complex
During the last expedition of the same type, in 2021, the roof of the Alps was measured at 4,807.81 meters, almost a meter less than the measurement taken in 2017 (that of 2019, very low, had been kept secret, because it is considered unrepresentative). Conversely, it was in 2007 that the highest altitude was recorded (4,810.90 m).
These variations are not surprising, geometers warn, because “since the dawn of time, the altitude of Mont Blanc has been continuously oscillating”.
The “rocky” summit of the mountain culminates at 4,792 m, but it is the thickness of the layer of “eternal snow” which covers it, functioning like an enormous snowdrift, which “varies depending on the altitude winds and the precipitation”, they detailed in 2021.
The altitude of the summit also varies according to the seasons, Mont Blanc being a dune complex where the wind, more violent in winter, scrapes the snow more than in summer. The summit is therefore higher at the end of the summer than in spring.
While the melting of glaciers is accelerating under the effect of global warming, which particularly affects the Alpine arc, one of the members of the team, Denis Borel, called for “remaining humble” and “not draw hasty conclusions on measurements which have only been carried out since 2001 with current precision.
European glaciers, particularly vulnerable to rising temperatures due to their relatively low altitude, lost around a third of their volume between 2000 and 2020, according to data compiled by scientists.
The melting suffered by the glaciers of the French Alps during the summer of 2022 has been described as exceptional, representing around 5 to 7% of the remaining glacial mass according to glaciologists.
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