Climate change threatens historical climate data stored in glaciers

Global warming is speeding up and it’s causing an unexpected problem: it’s making it harder for us to understand Earth’s past climate. A new study by the Ice Memory initiative has shown a worrying truth. The Corbassière glacier, which is in the Grand Combin massif, is melting quickly. This is destroying what used to be a useful source of climate data.

A study in Nature Geoscience compared two sets of ice cores and found that global warming has made the Corbassière glacier, at least, useless for studying past climates.

Ice Memory initiative

We can’t get reliable information about past climates and air pollution from the Corbassière glacier in the Grand Combin massif anymore. This is because the glacier is melting faster than we thought. Margit Schwikowski, who leads the Laboratory for Environmental Chemistry at PSI, and Carla Huber, a Ph.D. student and the study’s main author, came to this sad conclusion. They found this out when they looked at the signatures of tiny particles trapped in the yearly layers of ice.

Glaciers are like time capsules for climate scientists. They store information about past climates and atmospheric conditions in their ice, similar to how tree rings and ocean sediments do. This makes them a crucial resource for climate research.

Usually, the amount of tiny particles attached to substances in the ice changes with the seasons. These substances, like ammonium, nitrate, and sulfate, come from the air and end up on the glacier when it snows. There’s more of these substances in the summer and less in the winter, because less polluted air can rise from the valley when it’s cold.

In 2018, scientists drilled an ice core that was up to 14 meters deep. This ice core, which has deposits from as far back as 2011, showed the expected changes in the amount of these substances. But the ice core from 2020, which was up to 18 meters deep, only showed these changes in the top three or four layers of yearly ice. Deeper in the ice, which means further back in time, the changes in the amount of these substances were less noticeable, and the total amount was lower. This is what Schwikowski’s team found in their study.

Loss of climate data

Scientists found big differences between two sets of ice cores from 2018 and 2020. The 2018 core, which was up to 14 meters deep and had records going back to 2011, showed the usual changes in substances like ammonium, nitrate, and sulfate. These substances, which usually get onto the glacier when it snows, give us information about air pollution and climate conditions for each season.

But the 2020 core, which was up to 18 meters deep, showed a worrying trend. Only the top layers showed the usual changes. The deeper layers, which are older, showed less change and had fewer of these substances. This is like a library losing its books and the ones left getting mixed up.

The scientists think this happened because the glacier melted more between 2018 and 2020. This caused water from the surface to go deeper into the glacier and wash away these substances. This didn’t just dilute the records, it also got rid of them for good, which means we’ve lost some of the glacier’s historical climate record.

The scientists looked at weather data from 2018 to 2020 and found that it was warm on the glacier, which fits with the overall trend of the climate getting warmer. But these years weren’t unusually warm. Margit Schwikowski, who leads the Laboratory for Environmental Chemistry at PSI, said, “We think that there wasn’t just one thing that caused this strong melting. It probably happened because of many warm years in the recent past. It seems like we’ve crossed a line, which has led to a big effect.”

Race against time

There’s a growing concern that other glaciers worldwide, which haven’t been sampled as part of the Ice Memory project, might also be losing their valuable climate data due to rapid melting. In the Alps, the team has successfully obtained an intact ice core from the Colle Gnifetti, located on the Italian-Swiss border, which is even higher and colder than the Grand Combin glacier.

Researchers have already secured ice cores from Illimani in the Bolivian Andes, Belukha in the Russian Altai, and Elbrus in the Caucasus. Last year, they also conducted expeditions on Spitsbergen and the Col del Lys in Italy, but the analyses are still ongoing. Unfortunately, political and administrative issues caused the expedition to Kilimanjaro, home to Africa’s only significant ice body, to fail.

The Ice Memory project is indeed a race against time. Success is not guaranteed, and setbacks, like the one at Grand Combin, are becoming more likely each year. This underscores the urgency of addressing climate change and preserving these invaluable climate archives.

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