Global warming: glacial records lost forever

It took no more than two years for the Corbassière Glacier in Valais to become practically useless for studying climate change. This has been made clear by core sampling done as part of the Ice Memory initiative, which aims to preserve the memory of threatened glaciers.

“Lost to science!” That is the conclusion recently reached in a study conducted by scientists from the Paul Scherrer Institute and the University of Fribourg, along with other Swiss and Italian institutions. The study focused on the Corbassière Glacier. An initial core sample drilled by the scientists in 2018 allowed them to identify and correctly study the layers within this glacier in Valais. However, a second core sample drilled in 2020 turned out to be almost unreadable. The cause was the sharp acceleration in the melting of the ice in recent years. This melting is such that the glacier’s use as a vast record of earlier climate data is lost forever.

The deeper you drill into the glacier, the further you travel back in time
High-altitude glaciers are of major interest to scientists studying the climate and environment of recent millennia. At more than 4000 m above sea level, where temperatures rarely exceed 0 °C, snow accumulates each year without any prolonged melting phase. Each of these yearly layers of snow, called firn pack, contains a wealth of data. Studying the particles trapped there, specialists can identify episodes of drought, increased rainfall, forest fires, even the appearance of the first pollutants produced by the Industrial Age. To read this past, researchers drill core samples in the accumulation zones of glaciers. The lowest, that is deepest, layers are the oldest. The loss of glacial mass in recent years, however, has muddied the waters, so to speak.

A melting glacier is a library on fire
As part of the Ice Memory initiative, scientists turned their attention to the summit plateau of the Corbassière Glacier to complete the existing core-sampling sites located throughout the Alps. Initially they thought that the Corbassière Glacier would allow them to go back further in time than the other high-altitude glaciers already studied, like the Col du Dôme on Mont Blanc or the Col Gnifetti on Monte Rosa. Unfortunately, the team of scientists led by Dr. Margit Schwikowski, the director of the Laboratory of Environmental Chemistry at the Paul Scherrer Institute, had to give up their early optimism. The recent melting of upper layers caused significant meltwater flows down into the depths of the glacier. “That phenomenon washed out the particles that are normally looked for, like ammonium, nitrate, and sulfates. These particles had been trapped in the individual layers of ice until melting altered their presence in the upper strata. Swept down in the water flow, the upper particles in a way ‘contaminated’ the lower layers of the glacier,” lamented Enrico Mattea, a researcher at the University of Fribourg’s Department of Geosciences and coauthor of the paper. “This makes the climate and environmental records of the Corbassière Glacier impossible to read.”

Other core samples drilled at other sites on the glacier yielded the same results, so much so that the scientists had to call off the expedition. The goal of their initial project was to drill 80 m down into the glacier until they hit the solid rock beneath the ice. This would have allowed them to extract the complete record caught in the ice and travel thousands of years back in time. “Our analyses have just confirmed it. With the Grand Combin, we arrived too late,” Dr. Schwikowski concluded.