It is a sobering realization: By 2050, half of the glaciers in the Alps will have melted - regardless of whether or not they still manage to reduce their greenhouse gas emissions.
This is the conclusion of a study from Switzerland published in the journal "The Cryosphere". Because the glacier melt reacts only very slowly to climatic changes, the development in the coming decades is unstoppable, the researchers said.
And even for the period from 2050, the experts predict a dramatic development. So it could come in the second half of the century to an almost complete Eisfreiheit in the Alps. However, the process can still be influenced in this time window. "The future development of glaciers will depend heavily on how the climate develops," says study leader Harry Zekollari from ETH Zurich. "In the case of a weaker warming, a significantly larger part of the glaciers could be preserved."
The research team has created a detailed forecast for all around 4000 glaciers in the Alpine region. The study essentially confirms previous assumptions concerning the development of glaciers. What is new, however, is that the experts used computational models for their calculations, which take into account not only melting processes but also the movement of the ice. As starting values, they use data from the year 2017 - at that time the glaciers in the Alps had a total volume of around 100 cubic kilometers.
In the best case, only two-thirds of the glacier mass disappears
In order to predict the decline of glaciers according to the evolution of greenhouse gas emissions, the researchers used two scenarios from the report of the IPCC. These so-called Representative Concentration Pathways (RCP) scenarios are based on a large number of international studies and show how the climate could change depending on the greenhouse gas concentration and energy balance of the earth.
In the first scenario considered (RCP 2.6), greenhouse gas emissions only increase for a few years and then drop significantly. Global warming would thus be kept below two degrees below pre-industrial levels by the end of the century. In this scenario, there would be a melting of more than two-thirds of the alpine glacier volume.
The second scenario under consideration (RCP 8.5) assumes that greenhouse gas emissions will increase unchecked and that global warming will be significantly greater. "In this pessimistic case, the Alps will be virtually ice-free by the year 2100. Only a few ice sheets at high altitudes would remain and correspond to around five percent of the current ice volume," says Matthias Huss from the research team. It is not unlikely that this will happen, as global emissions are already above the levels of this scenario.
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According to the researchers, the glacier melt will have a strong impact on the Alpine region. Glaciers are not only an important part of the ecosystem, they also have a high economic importance. The meltwater is used for agriculture and energy. In addition, the huge ice surfaces in the mountains attract tourists.
The diagnosis is also clear for the worldwide development of glaciers: According to a study published in the journal "Nature" on Monday, the glaciers lose 335 billion tons of ice a year on a global scale. This amount causes the sea level annually increase by one millimeter, the researchers said.