The mass of glaciers around the world has been decreasing since the 1970s. The balance between snowfall and ice melt has been upset by global warming. Huge accumulations of ice are melting, weakening, collapsing and disappearing all over the world on an unprecedented scale. The result is the catastrophic effects of climate change, such as floods, droughts, disrupted water supplies, and economic damage. Glaciers provide for the needs of many people in areas such as water supply, agriculture, hydropower and tourism, so it is crucial to be able to accurately predict and plan for what will happen to them next.
In Switzerland, glaciers play a very important role, but they are also melting fast. According to the Swiss Academy of Sciences, glaciers in the country will lose more than six percent of their volume in 2022, the worst year on record. According to researchers, Switzerland’s largest glacier, the Alech Glacier, could lose half its volume by the end of the century.
Glaciologists usually use stakes, photographs and pictures to track the movement of glaciers over time. Random objects, such as wrecked planes, can also be useful. But now there is another, more accurate method that can help glaciologists more accurately model glacier behavior and predict its future. This can help decision makers in planning for glacier retreat or complete disappearance.
About 40 km south of the capital, Bern, lies the Spitz Laboratory, which developed a nuclear method based on signatures recorded in ice during nuclear weapons (NW) tests in the 1950s and 1960s. These tests released man-made radionuclides into the atmosphere, which then settled in the surface layers of glaciers around the world. Because the dates of the tests are known, determining the peak concentrations of these radionuclides, as well as their dispersion patterns due to ice movement, can help establish the chronological characteristics of the ice layers.
In 2019 and 2020, experts from the Spitz Laboratory and members of the Swiss Armed Forces climbed the Alech and Gauli glaciers in the rugged terrain of the Bernese Alps and collected valuable isotope data on ice movement. From each glacier, they took about 200 surface ice samples weighing up to 1 kg each – enough to detect low concentrations of radionuclides. They then melted the samples and used radiochemical methods to extract and purify isotopes of uranium and plutonium, which they then analyzed using a highly sensitive instrument – a multicollector mass spectrometer with inductively coupled plasma.
The researchers also applied other nuclear techniques to determine the presence of nuclear-test-related radionuclides in environmental samples: high resolution gamma spectrometry detected cesium and liquid scintillation counting detected tritium.