The Ålfotbreen glacier is located on a sandstone platform between fjords on the west coast of Norway. The ice sheet is susceptible to changes in temperature and has been declining since the late 1990s. This is Norway's 25th largest glacier and caps the unique landscape of scaly sandstone known as the Hornelen Basin. The basin formed during the Devonian period about 400 million years ago when tectonic plates collided with each other and later gradually thinned.

Satellite image of the Ålfotbreen glacier in Norway taken on August 23, 2003.A satellite image of the Ålfotbreen glacier in Norway taken on September 4, 2022.

The sandstone ridge extends from north to south, often flanked by cliffs up to 100 meters high. As Ålfotbreen recedes, more of this unique geology is gradually exposed.

The glacier's surface area fluctuates dramatically during winter and summer. This is partly because the glacier is located on the west coast, which receives about 600 centimeters (236 inches) of annual rainfall, making it one of the wettest places in Europe.

Ålfotbreen's mass increases with winter snow cover and decreases with summer melt. Heat waves will melt snow early, exposing the darker ice surface earlier and accelerating melting.

Scientists compare the glacier's winter accumulation with its summer loss to track year-to-year changes in the glacier's mass -- a calculation known as surface mass balance (usually measured in meters of water equivalent, the depth of water after ice melts). The Norwegian Water and Energy Directorate maintains 60-year records of Olvertebryn's mass, which are collected in the field and reported to the World Glacier Monitoring Service.

Most of the snow on the surface of Olfertbrün is the result of 1-3 summers of snow, known as "firn" (grained snow), which is the transitional stage to the formation of glacial ice. While snowy winters caused the ice cap to grow between 1989 and 1995, more frequent and intense heat waves since then have caused the glacier to decline.

"There have been many recent years, such as 2017, 2018, 2021, 2022 and 2023, where glaciers have lost most of their snowpack before the end of the melt season," said Mauri Pelto, a glaciologist at Nichols College. "This causes the glacier to decline as the more permanent ice and pellet snow melt."

The image above shows Alford Breen in the summer of 2003 (left) and the summer of 2022 (right). On August 3, 2003, there was more than a month left in the glacier melting period, and all the snow on the glacier had disappeared, resulting in a massive loss of glacier mass (3 meters of water equivalent). Similarly, on September 4, 2022, the glacier also lost most of its snow cover, resulting in a net mass loss, although not as severe as in 2003.

According to the World Glacier Monitoring Service (WorldGlacierMonitoringService), over the past ten years (2013-2022), Olfertbreen has lost an average of 1.07 meters of water equivalent per year. Over the past two decades, about half the summers, the glaciers ended the melt season without a snow cover. "The lack of sustained snow cover suggests that glaciers cannot survive current climate conditions," Pelto added.

Pelto led a review of the World Glacier Monitoring Service's 2022 mass balance data for 37 high mountain glaciers around the world and found that 34 of them had experienced a decline in mass. The analysis found that the average ice loss from glaciers that year was more than one meter, and that ice loss from mountain glaciers around the world has been accelerating over time.

Image from NASA's Earth Observatory, taken by Wanmei Liang using Landsat data from the U.S. Geological Survey.

Compiled source: ScitechDaily