Rescuing Earth’s icy memory

A race against time – this figure of speech perfectly describes the efforts of Margit Schwikowski and her team. The more inexorably climate change advances, the faster the glaciers shrink. Vanishing with them is the archive that has been accumulating inside them for many thousands of years: gases and particles locked in the depths of the ice layers. They reveal how the atmosphere was composed at the time the ice was deposited and allow conclusions to be drawn about past events. How warm was it in a particular time period? When did forest fires occur? Which plants did people cultivate in those days?

"We can look back 10,000 years, sometimes even more," explains Schwikowski, head of the Laboratory for Environmental Chemistry at PSI. She is a member of the board of the international foundation Ice Memory. Its mission is to extract ice cores from selected glaciers worldwide and store them safely in Antarctica, as rapidly as possible: "We feel a certain pressure, because it is clear to us all what’s happening to these glaciers," the chemist says. "We urgently need to act to prevent the valuable information they contain from being lost forever."

 Already today, analyses of glacier ice are yielding unique insights into past environmental conditions. But analytical methods are constantly advancing. In the future, researchers will surely be able to coax many more secrets from the ice – if it is still available to them. Ice Memory aims to ensure that it will be.  In addition to PSI, participating institutions, which are also founding members of the international foundation, include the Université Grenoble Alpes, Ca’ Foscari University of Venice, the French National Institute for Sustainable Development (IRD), the French National Centre for Scientific Research (CNRS), the National Research Council of Italy (CNR), and the French Polar Institute PaulÉmile Victor (IPEV). Ice Memory is supported by UNESCO, the United Nations Educational, Scientific and Cultural Organization.

Between altitude sickness and crevasses

The initiative was launched in 2015. It was logical that Margit Schwikowski should be asked to help establish the archive for ice cores: research on high mountain glaciers has been her specialty since 1992. "We are among the few research groups in the world that drill glaciers for ice cores," she says. This is no easy task, and requires a lot of experience. "Every glacier and therefore every borehole is different."

The expeditions to the glaciers, situated several thousand metres high, typically last a good week and are not without their dangers, adds Theo Jenk, a researcher at the PSI Laboratory for Environmental Chemistry and leader of the latest Ice Memory expedition. "The air is thin, and there’s always the risk of suffering from altitude sickness. We need to make sure we’re able to take sick members down again quickly in case of an emergency."

Altitude sickness, which can occur during stays at 2,500 metres or higher, manifests itself in headaches, confusion, and hallucinations; it can also lead to life-threatening pulmonary or cerebral oedema.

Hidden crevasses are another danger that goes with the territory when researchers are working in the mountains. In many places the team doesn’t move without being secured by ropes and climbing harnesses.

The modular, two and a half metre-long icecore drill with which the team gradually works its way down to bedrock under the glacier – often more than a hundred metres – is custom-made, developed and built by the company icedrill.ch in Biel, Switzerland. With the help of a winch – from which the drill is suspended by a cable and thus is controlled and supplied with electricity – the researchers pull 70-centimetre-long drill cores up from the depths, piece by piece.

"The work days up there are long," explains Theo Jenk. "We also work at night sometimes if it is too warm during the day." With too much exposure to the sun, the sensitive ice cores could be damaged through melting. There is also the danger that melt water will form on the drill, which then could freeze fast and get stuck in the borehole. To keep the arduously extracted cores cold enough, the researchers take insulation boxes up the mountain with them and bury them in the snow. The “cold chain” has to be maintained – using dry ice or refrigerated trucks if necessary – until the ice cores can be secured in cold storage.

Success at Colle Gnifetti

Last year the researchers managed to extract an ice core more than 80 metres long from a glacier in the Pennine Alps – to be precise, from the glacier saddle of Colle Gnifetti on the Monte Rosa massif at an elevation of 4,500 metres. For Ice Memory, obtaining a core like this was at the top of the list. "Here we have the highest glaciers in Europe, and these contain a lot of valuable information," says Theo Jenk.

So many freshwater sources are fed by the alpine glaciers, some call Switzerland the Wasserschloss or “moated castle” of Europe. That makes it all the more important to know how the glaciers are likely to develop in the future – and to have samples in hand that will allow comparisons with the past.

Besides Colle Gnifetti, the Ice Memory team is already protecting ice cores extracted from the Illimani glacier in the Bolivian Andes, from Belucha in Siberia, from Elbrus in the Caucasus, and from Col du Dôme on Mont Blanc in France (see map).

An especially worthy target to pursue next would be Kilimanjaro in Tanzania, the site of the only remaining glacier archive in Africa. According to Schwikowski, though, it is taking a long time to get authorisation from the Tanzanian government. Also on the wish list are Mount Logan in Canada, various glaciers on the Tibetan Plateau, and the Fedchenko glacier in Central Asia.

Two years too late

In 2020, a team from Ice Memory was under way on a major expedition in the Pennine Alps – in this case, on the Grand Combin massif at an altitude of 4,100 metres. Test drilling in 2018 had identified the area as a suitable site.

Two years later, however, when the researchers returned fully equipped for drilling, they hit a snag: after only half a metre, they encountered a hard layer of ice, and at 25 metres the drill got stuck for good. The reason: freeze-thaw cycles had produced melt water in the glacier’s collecting basin. Evidently it had been so warm between 2018 and 2020 that a large quantity of melt water had been able to penetrate far into the depths. Even if an ice core could have been extracted, it would have been useless for climate science. "We were totally shocked," Schwikowski says, "because it became clear that for this glacier, we were already too late."

According to the United Nations, almost all glaciers on Earth are shrinking – and with increasing speed. An international research team, with the participation of ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, recently found that glaciers worldwide had lost 227 billion tonnes of ice annually between 2000 and 2004 – between 2015 and 2019 the average was 298 billion tonnes per year. The study reports that the fastest melting glaciers include those in Alaska, Iceland, and the Alps.

Safe at the South Pole

At each site, the researchers take at least two ice cores. One of them serves as a reference and is, among other things, analysed at PSI; the data are made publicly accessible.

The second core is meant to be stored in an ice grotto in Antarctica, where no electricity is required to keep things cold. Another advantage that justifies the long-distance transport to the South Pole: this part of Earth is politically neutral ground and under the terms of the Antarctic Treaty is reserved exclusively for peaceful use, especially scientific research.

Currently, experiments are under way to determine how best to set up the repository. What is planned is a kind of ice cave that should provide a safe home for the ice cores, so they won’t meet the same fate as the glaciers from which they come. For Antarctica, at least, deglaciation is not expected to occur within the next hundred years.

Text: Brigitte Osterath