In Europe and around the world, melting glaciers are transforming both landscapes and national borders. In this article, researchers LJ Buslaviciutti and Dr. Laurinas Zukna from Vilnius University's Institute of Geosciences discuss space-based observations of this phenomenon.
The glaciers of Europe and their importance
When we think of glaciers, large ice sheets in polar regions often come to mind, such as Antarctica or Greenland. However, there are many more glaciers in the world and they are much more diverse. Worldwide, there are currently more than 200,000 glaciers that do not fall into the category of ice sheets (continental glaciers over 50,000 km²).
These include glacial valleys, hanging glaciers, mountain glaciers, ice sheets, etc., which are below 50,000 km² and often concentrated in mountainous regions. This type of glacier is also common in Europe, especially in Iceland, the Scandinavian Peninsula, Svalbard, the Pyrenees and the European Alps.
Glaciers are large bodies of ice that move under the force of gravity. They form where snow accumulation exceeds its disappearance. Over time, the snow compacts back—partially compacted granular snow—and eventually, turns into solid glacial ice.
Roughly 20,000-22,000 years ago, glaciers (or, more precisely, an ice sheet that moved from Scandinavia) shaped the present-day European landmass, leaving distinctive marks on the landscape that are still visible today. In modern times, glaciers continue to play an important role: they store fresh water, sustain Europe's rivers and lakes, and regulate both water flow and air temperature.
Observing melting alpine glaciers from space
Although glaciers in the Alps have retreated since the end of the Ice Age, human-induced global warming has accelerated their melting in recent decades. According to the long-term monitoring of Glacier Monitoring in Switzerland (GLAMOS), the area of glaciers in the Swiss Alps decreased from 1,311 km² in 1973 to 961 km² in 2016.
This represents a loss of about 350 km² of glacial area in less than half a century. Such large-scale observations are based on archival aerial and satellite imagery.
Glacier melt in southwestern Switzerland from 1850 to 2016 based on GLAMOS aerial and satellite observations. Right is a false-color Landsat 8 satellite image from 2 October 2016, with lines indicating the distribution of glaciers at different time periods.
NASA's Landsat mission, which has been observing Earth since 1972, has provided invaluable information on glacier loss. False-color Landsat satellite images show the much-visited Rhone Glacier and the source of the Rhone River in Switzerland. The image, consisting of near-infrared, red and green bands, highlights the glacier in blue-white tones, while the surrounding vegetation appears red. A comparison of images taken in August 2001 and August 2024 reveals a striking reduction in the area covered by the glacier.
Rhône Glacier in Switzerland in August 2001 and August 2024 based on false-color images from the Landsat 7 and 8 satellites.