How the glaciers of the Alps have melted over the decades

Due to the climate crisis, glaciers are retreating worldwide. And faster and faster: in recent years, the ice has disappeared up to three times faster than in the 20th century. The approximately 5,000 glaciers in the Alps lost a sixth of their ice volume in just 15 years. According to calculations, their number is likely to halve in the next few years.

For more than 120 years, the World Glacier Monitoring Service (WGMS) has been collecting data on changes in glaciers worldwide. The experts observe reference glaciers – glaciers that are supposed to represent the many glaciers – in around twenty mountain regions around the world. Among them are 13 Austrian glaciers.

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Pasterze is shrinking by 50 meters every year

At around eight kilometers, the Pasterze is the longest glacier in the Eastern Alps and the largest in Austria. It is located at the foot of the Grossglockner in the Hohe Tauern National Park. According to the Austrian Central Institute for Meteorology and Geodynamics (ZAMG), the glacier lost 37 meters of ice thickness over the entire area between 1969 and 2012. The Pasterze glacier is now receding by around fifty meters every year.

Experts agree: the glaciers will continue to lose ice, even if global warming stops, because they react to the rise in temperature with a delay. The melting glaciers have a direct impact on us humans and our environment. Biodiversity disappears with the glaciers. Former glacial valleys are transformed into desolate rocky deserts in which only a few creatures feel at home.

More and more glacial lakes

Higher temperatures also cause the so-called permafrost to thaw. Around one sixth of the entire earth’s surface is considered permafrost. It is characterized by the fact that the ground there is permanently frozen for at least two years. If it thaws, loose rock can loosen and fall down into the valley. Researchers from ETH Zurich have observed numerous rockfalls on the Swiss Aletsch Glacier since 2011 – in 2016 alone 2.5 million cubic meters of rock broke off.

An unmistakable sign that the glaciers are melting are also growing or newly emerging glacial lakes. Researchers discovered 180 glacial lakes in the Swiss Alps that had formed in the past decade alone. Lower-lying glacial lakes can pose a hazard to those around them – the pressure can cause walls of boulders to collapse and water to spill into the valley below. The glacial lake Cachet in Patagonia has already triggered several floods.

sea ​​level rises

When the glacial water flows into the sea, it contributes to sea level rise. In April 2019, researchers from ETH Zurich proved that glacier melt has caused sea levels to rise by an average of one millimeter in recent years. The glaciers in Alaska, Patagonia and in the arctic regions around the North Pole made a particular contribution to this. Annually, the 19,000 glaciers surveyed lost 335 billion tons of ice.

However, melting glaciers can also lead to drought. In some areas – for example in the Andes and the Himalayas – glaciers are at times the most important source of drinking water.