Monday, January 21, 2019

Mapping Shrinking Glaciers

The Rhône Glacier in the Swiss Alps is the source of the Rhône river. Over the last 120 years the glacier has shrunk by a very large extent. In recent years, during the summer months, the glacier has been covered with UV-resistant fleecy white blankets. These cover about 5 acres of the shrinking glacier and are believed to reduce its melting by up to 70%.

You can view how far the Rhône Glacier has melted using the superb maps produced by the Swiss Federal Office of Topography. The Karten der Schweiz, the official mapping platform of the Swiss Confederation, includes an option to view vintage maps made by the Swiss Federal Office of Topography. You can even animate through these vintage maps to show how locations have changed over time.

For example you can animate through all the maps of the Rhône Glacier from 1850 to the present day. The resulting animated map is a very effective visualization of the startling extent by which the Rhône Glacier has shrunk over the last century.

You can also use Google Earth Engine to view how the glacier has shrunk over recent years as seen on satellite imagery. Google Earth Engine only has satellite imagery going back as far as 1984. Therefore the extent of the glacier's retreat isn't as pronounced as can be seen by viewing the historical Karten der Schweiz. However even since 1984 it is possible to observe that the glacier has visibly shrunk in size.

Since 1850 Switzerland's glaciers have shrunk by around 50%. The World Glacier Monitoring Service say that this process is likely to continue and that 80 to 90 percent of glacier ice mass will be lost by 2100.

In 2017 the Swiss newspaper Tages Anzeiger visualized the extent of Switzerland's shrinking glaciers over the last 160 years. In So Schmolzen die Schweizer Gletscher in 160 Jahren Weg the paper produced a series of multiple maps visualizing the change in size of the country's 38 largest glaciers. These maps show the size of the glaciers in 1850 compared to the size of the glaciers in 2010. Each mini map includes data on the surface area lost in kilometers and as a percentage of the glacier's size in 1850.

Tages Anzeiger reports that the Rhône Glacier has shrunk by 4.7 km² or about 23.4% in size.

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