Glacial Losses in the Swiss Alps
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- aletschglacier_tm5_19840902_lrg.jpg (893x744, JPEG)
- aletschglacier_oli_20240806_lrg.jpg (893x744, JPEG)
Metadata
- Sensor(s):
- Landsat 5 - TM
- Landsat 8 - OLI
- Data Date: September 2, 1984 - August 6, 2024
- Visualization Date: March 13, 2025
Spanning more than 1,000 kilometers across eight European countries, the Alps are among the planet’s largest and highest mountain ranges. The terrain is home to thousands of glaciers, including the range’s largest—the Great Aletsch Glacier (Grosser Aletschgletcher) in southwestern Switzerland. But like many glaciers in the Alps, the Aletsch is retreating and thinning.
Change across the past four decades is visible in this image pair. The TM (Thematic Mapper) on Landsat 5 captured the left image in September 1984, and the OLI (Operational Land Imager) on the Landsat 8 captured the right image in August 2024.
As of March 2025, it was still too early in the year to acquire a new image without seasonal snow obscuring the glacier. Even in these late-summer scenes, minor differences might still be related to snow. Even so, changes to the length and width of the glaciers are clearly visible. (Note that clouds obscure some of the smaller glaciers toward the right side of the image.)
The shortening and narrowing of a glacier’s surface area—parameters visible in Landsat images—can indicate a net loss of ice mass. For example, imagine two equal-sized bowls filled with different amounts of water; the bowl with less water would display a lower surface height and smaller area. The same is generally true for glacial ice that flows along U-shaped valleys.
According to the Swiss Glacier Monitoring Network (GLAMOS), Aletsch has retreated more than 1,300 meters (4,300 feet) since 1984. It has also thinned, contributing to the glacier’s narrower appearance in the 2024 scene. In the span of four decades, GLAMOS data indicate that the glacier has lost 43 meters of water equivalent.
Aletsch’s neighbors also show decline, albeit more subtly. Since 1984, Oberaletsch Glacier to the left has retreated more than 240 meters, and Fiescher Glacier to the right has retreated more than 1,000 meters.
These images follow a particularly warm summer in 2024 that melted the abundant snowfall from the previous winter, according to news reports. Swiss glaciers that year lost 2.5 percent of their volume.
Glaciers in other parts of the world, such as Alaska in the United States, have contributed more in terms of total mass loss, according to a recent assessment of the glacier mass changes in regions across the planet between 2000 and 2023. However, the largest relative losses during that period occurred in areas with smaller glacial area. Central Europe, for example, which includes Switzerland, lost 39 percent of its glacial ice during that time.
References
- The Associated Press (2025, February 20) Climate change is shrinking glaciers faster than ever, with 7 trillion tons lost since 2000. Accessed March 13, 2025.
- BBC (2025, February 19) World’s glaciers melting faster than ever recorded. Accessed March 13, 2025.
- The European Space Agency (2025, February 19) Glacier melt intensifying freshwater loss and accelerating sea-level rise. Accessed March 13, 2025.
- Glacier Monitoring Switzerland (2024) Swiss Glaciers. Accessed March 13, 2025.
- The GlaMBIE Team (2025) Community estimate of global glacier mass changes from 2000 to 2023. Nature, 639, 382–388.
- Reuters (2024, October 1) Swiss glacier melt exceeds average in 2024 after hot summer. Accessed March 13, 2025.
- UNESCO (2025) Swiss Alps Jungfrau-Aletsch. Accessed March 13, 2025.
- World Glacier Monitoring Service (2024, January 23) Grosser Aletschgletscher. Accessed March 13, 2025.
NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen with image interpretation by Christopher Shuman, UMBC (retired).
This image record originally appeared on the Earth Observatory. Click here to view the full, original record.