France's tallest mountain shrinks by more than two metres in a couple of years

The highest mountain in France has lost two metres in height over the past two years, new research found.

Scientists this year measured Mont Blanc's peak to be 4,805 metres, which is 2.22 metres shorter than in 2021, the BBC reports.

An exceptionally dry and scorching hot Northern Hemisphere summer could have caused the shrinking, chief geometer Jean des Garets said.

READ MORE: France steps up war on bedbugs after public outcry

Known as the 'roof of Europe', Mont Blanc, in south-east France, attracts up to 30,000 climbers every year who set out to ascend it.

It is measured every two years to track the impacts from climate change.

But des Garets was cautious about what caused the latest shrinkage of its peak.

"The summit is constantly changing in altitude and position, with changes of up to five metres," he said.

"Mont Blanc could well be much taller in two years."

Other research from 2021 suggests the mountain, on average, is losing about 1.3 metres annually.

"We're gathering the data for future generations," des Garets said.

"We're not here to interpret them, we leave that up to the scientists."

The rocky peak of Mont Blanc sits at 4,792 metres above sea level, but the amount of snow and ice at the summit can lead to a disparity in height.

READ MORE: New Zealand airport evacuated after suspected bomb found

Les rain through Europe's dry summer months could have caused the mountain's loss in height this year, the researchers said.

Earth sweltered through its hottest Northern Hemisphere summer ever measured, with a record warm August capping a season of brutal and deadly temperatures, according to the World Meteorological Organisation.

August was about 1.5 degrees warmer than pre-industrial averages.

That is the threshold that the world is trying not to pass, though scientists are more concerned about rises in temperatures over decades, not merely a blip over a month's time.