April 1 (UPI) -- As showcased by NASA's "Image of the Day," the Länta Glacier is significantly smaller than it was 20 years ago.
This week, NASA shared a series of images captured by its Landsat satellites. The Landsat program is the longest-running mission dedicated to capturing satellite imagery of Earth.
Glaciers in the Alps, like other alpine glaciers, are relatively small compared to polar glaciers. The collection of glaciers in the Swiss Alps cover just 0.4 square miles.
Before global warming, Swiss Alps glaciers covered significantly more surface area. Like its neighbors, Länta Glacier is much smaller than it was 20, 50, 100 years ago. Glacial records suggest Länta Glacier was three times its current size in 1850.
The two images shared by NASA this week showcase the glacier's decline over the last 20 years. The Thematic Mapper on the Landsat 5 satellite captured the 1989 image, while Landsat 8's Operational Land Imager captured the 2017 image.
NASA scientists laid the topographic data atop images captured by NASA's Shuttle Radar Topography Mission. The layered composite images feature visible, near-infrared and shortwave infrared light. Researchers used false color to accentuate the glacier's surface area.
Though a general trend of decline has been measured among alpine glaciers across the globe, in North America, Europe and Asia, variability remains. Some glaciers have shrunk more than others in recent decades.
"There are differences in individual years among the regions, mainly due to snow amounts in winter," Matthias Huss, a glaciology and hydrology expert at University of Fribourg, said in a news release. "And not all glaciers melt at the same speed due to their differing shape and, therefore, sensitivity."
Though smaller than the glaciers found in Greenland and Antarctica, alpine glaciers are vital for many communities across the globe, their outflows providing fresh water and electricity.
"Alps glaciers, like Länta, are also relevant to hydropower production, and, of course, tourism," Huss said.