France's highest mountain, Mont Blanc, has shrunk by over two metres in height over the past two years, researchers said on Thursday, measuring the Alpine peak at 4,805.59 metres.
The 2.22-metre decline could be down to lower precipitation during summer, said Jean des Garets, chief geometer in the Haute-Savoie department of southeastern France.
"Mont Blanc could well be much taller in two years" when it is next measured, he added, saying 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 garner information about the impact of climate change on the Alps.
"We're gathering the data for future generations. We're not here to interpret them," des Garets said.
People shouldn't use the height measurement "to say any old thing", he urged.
Instead, "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 shrinkage.
Mont Blanc's highest recorded summit was in 2007, at 4,810.90 metres.
A one-metre fall was measured in 2021 compared to 2017 -- after 2019's unusually low result was kept secret as experts judged it not representative.