According to a new study, the volume of Swiss glaciers halved between 1931 and 2016. For the first time, researchers reconstructed the retreat of glaciers in the 20th century for the whole of Switzerland – using historical image material.
The study, published in the journal “The Cryosphere“, shows that there was a significant retreat of glaciers in the period examined, as announced by ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) on Monday.
Not all the same
Although not all glac-iers melted every year, in the 1920s and 1980s the mass even increased in some cases, but overall the climate in the 20th century was unfavorable for glaciers. In addition, the glaciers have melted faster and faster over time. The study also shows that not all glaciers were equally affected by the retreat. The extent to which a glacier has melted depends on the altitude at which it is located, how flat the glacier tongue is and how heavily it is covered with debris.
What is special about the study is a new data basis. Using 21,700 photographs taken between 1916 and 1947, the researchers determined the surface of the glac-iers at two different times. They then calculated the difference in volume and reconstructed the topography of all Swiss glaciers for the year 1931. Comparisons were then made with data from the 2000s.
Unique reconstruction
This is the first time experts have reconstructed how glac-iers developed in the 20th century. So far, the picture of glacier changes has been based primarily on long-term glacier observations and measurements in the field and on the basis of aerial photographs from the years after 1960. In addition, regular measurements have only been carried out on a few Swiss glac-iers, for example on the Claridenfirn. This older data can also be more biased as errors from earlier, inaccurate, or uncertain measurements accumulate.
