A century after Walter Mittelholzer’s famous aerial mission, scientists repeat his journey to shed light on the impact of global heating

In 1919, the Swiss pilot and photographer Walter Mittelholzer flew over Mont Blanc in a biplane photographing the alpine landscape. A century on, scientists have recreated his images to show the impact of global heating on the mountain’s glaciers.

Dr Kieran Baxter and Dr Alice Watterson from the University of Dundee used a process called monoplotting to work out the precise locations from which Mittelholzer had taken his photographs. They returned to the spot in a helicopter and lined up their cameras using the alpine peaks as their guide.

Facebook Twitter Pinterest Walter Mittelholzer, the Swiss pilot and photographer who flew over Mont Blanc in a biplane in 1919. Photograph: Bibliothek Zürich, Bildarchiv/University of Dundee

The scientists captured images of three glaciers that Mittelholzer had also photographed: the Bossons glacier, the Argentière glacier and the Mer de Glace, all on the northern side of the Mont Blanc massif.

The resulting photographs show just how much ice has been lost from the region over the past century.

Mont Blanc Bossons glacier Mont Blanc Bossons glacier, then and now.

Baxter said: “The scale of the ice loss was immediately evident as we reached altitude but it was only by comparing the images side-by-side that the last 100 years of change were made visible.

Facebook Twitter Pinterest Kieran Baxter in a helicopter, photographing the precise spots where Mittelholzer went in 1919. Photograph: University of Dundee

“It was both a breathtaking and heartbreaking experience, particularly knowing that the melt has accelerated massively in the last few decades.”

The Mer de Glace, the longest glacier in France, is the site of the biggest changes over past decades. In the 1800s, travel writers described how it could be seen from the resort town of Chamonix, but it has since receded more than 2km up the mountain’s slopes.

Facebook Twitter Pinterest Kieran Baxter at one of the Mont Blanc glaciers found to have diminished. Photograph: Alice Watterson/University of Dundee

The Mer de Glace “is now melting at the rate of around 40 metres a year and has lost 80 metres in depth over the last 20 years alone,” the glaciologist Luc Moreau told the Guardian last year.

Mittelholzer, who trained as a military pilot during the first world war, later became the director of a commercial aviation company that later became the Swiss national carrier, Swissair. He died in a climbing accident in 1937.

Argentière glacier in 1919 and 2019 Argentière glacier: the change over a century.

Baxter said: “Mittelholzer played a key role in popularising commercial air travel in Switzerland, an industry which ironically came to contribute to the warming of the climate – and the detriment of the alpine landscapes.”

The Dundee scientists said they were careful to keep their own impact on the environment to a minimum.

Mer de Glace glacier in 1919 and 2019 How the Mer de Glace glacier has changed over a century.

“When working at these heights there is currently no viable emission-free alternative so airtime is kept as brief as possible and careful planning goes into getting the most out of a photography flight like this one,” said Baxter.

“Luckily, clear weather allowed these repeat aerial photographs to be taken on the centenary year of the originals. Unless we drastically reduce our dependence on fossil fuels, there will be little ice left to photograph in another hundred years.”

• This article was amended on 24 October 2019 to correct the caption of an image that said it depicted Walter Mittelholzer flying over Mont Blanc. In fact, the image shows Mittelholzer further east, over the Bernese Alps in Switzerland.