By analyzing ice collected from glaciers, scientists can study the past composition of the atmosphere and better understand how humans have altered the climate. But the rapid melting of ice may be compromising this critical data, according to a study of the Corbassière glacier in Switzerland.
The Corbassière glacier on the Grand Combin massif is a living inventory of air pollution. Bits of pollution clinging to falling snow gather on the surface of the glacier, with each new layer of ice recording the most recent level. In summer, when the air is warmer, more pollution rises from the valley below and settles on the ice.
An ice sample taken in 2018 showed the seasonal rise and fall of air pollution dating back several years, but a sample taken in 2020 was thoroughly muddled. Scientists could see the seasonal fluctuation in 2019, 2018, and 2017, but going back further into the past, it disappeared.
Scientists believe that, between 2018 and 2020, meltwater trickled deep into the glacier and drained away much of the pollution trapped within. Their study was published in Nature Geoscience.
“The climate archive is destroyed,” scientists said in a statement. “It is as if someone had broken into a library and not only messed up all the shelves and books, but also stole a lot of books and mixed up the individual words in the remaining ones, making it impossible to reconstruct the original texts.”
The Corbassière glacier at the Grand Combin is one of 20 endangered glaciers worldwide from which scientists are racing to gather ice samples to preserve a permanent record of the past climate. But at Grand Combin, said study coauthor Margit Schwikowski, “we’re already too late.”