Mont Blanc, western Europe's highest mountain, has shrunk by more than two metres over the past two years, researchers said on Thursday, measuring the Alpine peak at 4,805.59 metres.
Less rain and snow during the summer is thought to be the cause for the 2.22-metre decline, said Jean des Garets, chief geometer in the Haute-Savoie department of south-eastern France.
"Mont Blanc could well be much taller in two years" when it is next measured, he said, and this was not the first time such a large change had been seen.
The mountain's rocky peak measures 4,792 metres above sea level, but its thick covering of ice and snow varies in height from year to year depending on wind and weather.
Researchers have been measuring it every two years since 2001, hoping to gather information about the effects of climate change on the Alps.
"We're gathering the data for future generations. We're not here to interpret them," Mr des Garets said.
People should not use the height measurement "to say any old thing", he said.
"It's now up to the climatologists, glaciologists and other scientists to make use of all the data we've collected and come up with theories to explain" the shrinking.
Mont Blanc's highest recorded summit was in 2007, at 4,810.90 metres.
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A one-metre fall was measured in 2021 compared to 2017 – after 2019's unusually low result was kept secret as experts considered it not to be representative.
"Mont Blanc's height has been fluctuating since time immemorial," the geometers say.
Within the year, strong winter winds usually scour away more snow than in summer, meaning the peak is higher as autumn begins than in early spring.
"We've learnt a lot from these measurement campaigns," Mr des Garets said. "We know that the summit is constantly changing in altitude and position, with changes of up to five metres."
Luc Moreau, a glaciologist, told AFP that since the ice cap at Mont Blanc's summit was at a temperature of minus 15°C it could not melt.
"So there is no link to global warming," Mr Moreau said.
But this could change if climate change intensified, he said.
Faster melting has been observed in Alpine glaciers as a result of climate change.
European glaciers, many at lower altitudes than elsewhere in the world, are especially vulnerable to global warming.
They lost about a third of their volume between 2000 and 2020, according to scientific data.
In 2022 alone, glaciologists believe up to 7 per cent of the remaining mass of the glaciers may have vanished.
But one of the Mont Blanc team members, Denis Borel, urged people to "stay humble" about climate's impact on the mountain.
People shouldn't "draw hasty conclusions about measurements that have only been made precisely since 2001", Mr Borel said.
About 20 people scaled the mountain in mid-September to carry out the measurements over several days.
They were divided into eight parties equipped with high-tech tools and, for the first time, a drone.
