Before-and-After Satellite Images Show Upsetting Glacier Loss in Swiss Alps

The European Alps cover over 600 miles (1,000 kilometers) across eight European countries, and their cooler upper climes contain thousands of glaciers. Unfortunately, NASA satellite imagery recently captured 40 years of regression in the Alps’ largest chunk of ice, the Great Aletsch Glacier.

The images—seen below, and taken in 1984 and 2024—were snapped by NASA’s Landsat 5’s Thematic Mapper and Landsat 8’s Operational Land Imager (OLI), respectively. The changes to the glacier’s length and width are apparent, reflecting a retreat of more than 4,300 feet (1,300 meters) in those 40 years.

According to a NASA Earth Observatory release, the glacier has also thinned in that time—to the tune of about 141 feet (43 meters) of water, based on data from the Swiss Glacial Monitoring Network (GLAMOS). In other words, its footprint has shrunk in both dimensions.

Despite some cloud cover in the newer image, the loss of ice is clear. Where ice once reflected bright white back up towards the atmosphere, there are more grayish-brown rock underneath. According to the NASA release, it was too early in the year to capture imagery of the glacier without seasonal snow covering the amount of glacial melt that’s occurred in the intervening years.

Alpine glaciers are retreating across the board. The nearby Oberaletsch glacier has retreated more than 787 feet (240 meters) since 1984, and the Fiescher Glacier’s retreat over the same time period has been a staggering 3,281 feet (1,000 meters).

According to a Reuters report published late last year, Swiss glaciers melted at an above-average rate in 2024, despite heavy snowfalls in winter and spring. The winter storms were simply not enough to counteract record ice losses in the face of a warm August—and even a dose of Sahara desert dust, which made it harder for the Swiss ice sheets to reflect sunlight back into the atmosphere.

In 2024, Swiss glaciers lost 2.5% of their volume, according to Reuters. Central Europe, including Switzerland, lost a staggering 39% of its glacial ice between 2000 and 2024, as a team of researchers reported in Nature this year.

The NASA imagery puts those changes into sharp relief. Coming out of a record warm February—the third-warmest on record, according to the National Oceanic and Atmospheric Administration—there’s a real worry (and expectation) that we’ll likely see more photos of glacial losses in the near future.