Swiss glaciers have more than halved since the 1930s

This emerges from a new Swiss reconstruction, appeared this week in the magazine The Cryosphere. Although there have been periods when the glaciers have shrunk back a bit, the trend is generally for an acceleration in retreat, according to scientists from the ETH Zurich Institute of Technology and the Swiss government.

Although researchers have been tracking glaciers using aerial photographs since the 1960s, and satellites and other equipment for about 20 years, there have been no good reconstructions from longer ago. For this purpose, the scientists used more than 20,000 stereo photos that researchers from the Swiss Topographical Service took of the landscape between 1916 and 1947.

Using modern digital techniques, the researchers converted them into three-dimensional images of the landscape of the past. This way, they were able to trace exactly how much mass has been lost since then. Result: about half of the glaciers disappeared between 1930 and 2016. We already knew that after that, an additional 12% had melted.

Delayed reaction

“Important research”, reacted the meteorologist and glaciologist Peter Kuipers Munneke on Tuesday morning in a discussion of results on Radio 1. “We know that even if global warming stopped today, 60% of what currently exists would disappear in the next century, simply because glaciers react with a delay to warming. We will have to live with the fact that in the future the glaciers of the Alps will become much smaller than we and our generations have always seen them.

There are also tangible consequences. For example, Switzerland’s electricity supply relies 60% on reservoirs, which in turn depend on a predictable supply of spring meltwater. Rivers like the Rhône, Danube and Rhine are also expected to become more erratic as glaciers disappear.

For years, Swiss winter sports tourism has been increasingly confronted with the melting of the mountains. It’s also dangerous: in the Italian Alps, on July 11, people died when a glacier tip broke off.

bare rocky plains

Not all glaciers are disappearing at the same rate, the researchers note. How quickly a glacier disappears depends on its height, the amount of debris on it, and the slope or flatness of the landscape. Old glass plate photos, however, show a stunning image. on reconstructions made available by ETH Zurichshows how white winter landscapes transformed into arid rocky plains in less than a century.

Glaciers are known as “canaries in the coal mine” susceptible to climate change because they can become unstable even with a relatively small temperature increase. In Switzerland, it has increased by around 2 degrees since the end of the 19th century.