Corbassière glacier: Earth's natural climate archives • Earth.com

Corbassière glacier: Earth's climate archives are melting away

Today’s Image of the Day from NASA Earth Observatory features the Corbassière glacier, a high-altitude glacier in Switzerland. The glacier originates on the northern slope of the Grand Combin, which is one of the highest peaks in the Pennine Alps.

Collectively, the alpine glaciers of Switzerland have lost more than half of their volume since the 1930s.

“Glaciers are natural archives of past climate. In their frozen layers lies evidence of Earth’s changing temperature and atmospheric composition. But as the climate warms, some of the longest records of our changing planet are melting away,” said NASA.

“In just over two decades, Corbassière has shrunk in area and surface mass. The glacier was darker in 2023 due to lack of snow, and the glacier’s tongue had retreated.”

To reconstruct past concentrations of atmospheric aerosols, a team of scientists analyzed ice cores that were collected from the Corbassière glacier in 2018 and 2020. 

Aerosols are tiny airborne particles that are deposited in the ice. “Such information from glaciers around the world can provide clues about past environmental conditions thousands of years ago,” noted NASA.

“Ice cores contain ammonium, nitrate, and sulfate ions – signatures of aerosols lacing the snow that’s deposited on glaciers year after year. Ion concentrations are lower in winter than in summer because less polluted air can rise from the valley when the air is cold.”

When the researchers analyzed the ice core from 2018, they found seasonal fluctuations in the amount of ion deposits – which is what they expected to find. 

“But when we went to core the glacier in 2020, we noticed melting on the surface right away,” said Margit Schwikowski, an environmental chemist at Paul Scherrer Institute in Switzerland. 

The experts determined that melting on the glacier’s surface likely penetrated the glacier layers below and carried away the aerosol ions. “This melting rendered the core unusable in the team’s research, and other attempts to core the glacier had the same result. The valuable information stored in the ice was destroyed,” explained NASA.

Schwikowski has joined a team of other experts in an effort to preserve cores from the last remaining glaciers. Led by the Ice Memory Foundation, the goal of the project is to obtain ice cores from 20 endangered glaciers around the world in 20 years and collect them in a global climate archive.

“Glaciers are retreating worldwide, and we may find similar issues at other sites,” said Schwikowski. She added that even at the highest altitudes in the Alps, “glaciers are on the verge of becoming unsuitable as natural paleo-archives.”

Image Credit: NASA Earth Observatory

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