Swiss glaciers have shrunk by half since 1931, and melting faster, study reveals

Swiss researchers said on Monday that a study has revealed that Swiss glaciers have shed half their volume since 1931 and the ice melt is accelerating.The study was the first reconstruction of the country's ice loss in the 20th century. Researchers from the ETH Zurich technical university and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL say they had now reconstructed the topography of all Swiss glaciers in 1931, which will show how they have evolved.

Climate change has led to rapid glacier melt in several places, which is being closely monitored since the 2000s. But there has not been a definite way to show how the glaciers changed during the 20th century.

"Based on these reconstructions and comparisons with data from the 2000s, the researchers conclude that the glacier volume halved between 1931 and 2016," they said in a statement.

Thestudy, published in the scientific journal The Cryosphere, used material from the TerrA image archive, which covers about 86 percent of Switzerland's glacierised area, analysing around 21,700 photographs taken between 1916 and 1947.

The glaciologists used stereophotogrammetry, a technique used to determine the nature, shape and position of any object on the basis of image pairs, to do the reconstruction.

"If we know the surface topography of a glacier at two different points in time, we can calculate the difference in ice volume," lead study author Erik Schytt Mannerfelt said in the statement.

Side-by-side picture pairs showing the same spot nearly a century apart were presented in the study. The pictures show a dramatic change has taken place. The Fiescher Glacier, for instance, resembled a massive sea of ice in 1928, but in 2021, a few tiny specs of white were all that remained on the lush green mountainside.

The study used the mean year 1931 as a reference and reconstructed the surface topography of all glaciers for that year, the statement said.

The researchers added that glaciers did not continuously recede over the past century and there was even sporadic mass glacier growth in the 1920s and 1980s. However, Daniel Farinotti, a glaciology professor at ETH Zurich and WSL and co-author of the study, said that despite this growth, it was "important to keep the big picture in mind".

"Our comparison between the years 1931 and 2016 clearly shows that there was significant glacial retreat during this period," he said in the statement.

Farinotti said the evidence was clear: "Glacier retreat is accelerating".

While Swiss glaciers lost half their volume in the 85 years leading up to 2016, the Swiss glacier monitoring network, GLAMOS indicates that they lost a further 12 percent in the following six years alone.

(With inputs from agencies)