Heat in the mountains, lack of water in the lowlands – knowledge

The southern Schneeferner did not survive the summer. In September, the Bavarian Academy of Sciences denied the ice surface on the Zugspitze its status as a glacier, and the Schneeferner is now considered “dead ice”: Even at the deepest point, the ice is less than six meters thick, and it should be in the next one to two years it all melted away. The Germans Alps only four glaciers count: the Blaueisgletscher, the Watzmanngletscher, the Höllentalferner and the Northern Schneeferner.

It is not only in the German part of the Alps that the ice loss has been enormous in recent months. “This year was really extreme,” says glaciologist Wilfried Haeberli, professor emeritus at ETH Zurich. “We can already say that the mass loss of the glacier was significantly higher than in the previous record year 2003.” The Swiss glaciers alone, the largest in the Alps, lost more than six percent of their volume. This was not just due to the high temperatures. Small amounts of snow from the winter and a lack of summer snowfall led to an unusual large amounts of Saharan dust settled on the ice.The dust is darker than ice or snow and therefore absorbs more solar radiation.

Since the end of the Little Ice Age in the middle of the 19th century, the Alpine glaciers have been melting with only a few interruptions. “Nowhere else can the change in the climate system be observed as well as on glaciers,” says Haeberli. According to the 2021 published second Bavarian glacier report Alpine glaciers lost an average of more than one meter of ice thickness per year between 2000 and 2011. With an average glacier thickness of 45 meters, this means that even with the conservative assumption of constant melting by the middle of this century, three quarters of the remaining ice will disappear.

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“In a few decades, summer water shortages will become commonplace.”

This is not only a pity for the glaciers themselves, but increasingly also poses problems for the lowlands. Large European rivers such as the Po, Rhone and Rhine rise in the Alps, on the one hand fed by precipitation. But the mountains also store water in the form of snow and ice, which has so far ensured water availability even in months with little rainfall and high temperatures. After the snow cover has usually completely melted sometime between May and June, the meltwater comes from the glaciers alone – in the Rhone, glacier water accounts for around 15 percent of the year. That doesn’t sound like much. But the glaciers are melting at precisely the time when dry spells are particularly common. In addition, the snow cover melts earlier in the year as temperatures rise. Without meltwater, many rivers depend solely on rainfall in summer and are therefore subject to strong fluctuations. “In a few decades,” says Haeberli, “water scarcity in the summer will become a habit.”

According to hydrologist Kerstin Stahl, professor at the Albert-Ludwigs-Universität Freiburg, the meltwater already no longer compensates for long dry periods and high evaporation rates. The Alpine glaciers are already too small for that. Stahl, together with other scientists, investigated what this means for the Rhine within the framework of the International Commission for the Hydrology of the Rhine Basin (CHR). you come to the conclusion that the entire discharge regime of the Rhine is changing. From two maximum discharges in spring and summer, it shifts to just one maximum in winter. “Of course, that’s suboptimal. Lots of precipitation and runoff in winter do little to counteract drought in summer,” says Stahl.

The Great Aletsch Glacier is the largest and longest glacier in the Alps in terms of area.

(Photo: Sepp Spiegl/imago/sepp spiegl)

This is particularly true for years of extreme drought, which are likely to become more frequent and more intense in the future. Three drought events stand out from the last 50 years: 1976, 2003 and 2018. The KHR has examined more closely what will happen in the future if there is no glacier water in such years. By the end of the century, the total volume of water in the Rhine could drop by 30 to 50 percent in August. This is particularly critical in the area of ​​the Middle and Lower Rhine, i.e. from Rhineland-Palatinate to North Rhine-Westphalia to the Netherlands. In the high mountains, the amounts of precipitation remain relatively high. In the lowlands, on the other hand, there is no water when there is no glacier water from the mountains at high temperatures and little rain.

If there is less water in the river, the water temperatures also rise

As early as 2018, low water levels were affecting shipping on the Rhine. According to the KHR, there could be restrictions every year in more than two months by the end of the century. Around 80 percent of all inland waterway freight traffic in Europe is handled via the Rhine. And it’s not just shipping that relies on well-filled rivers. Power plants and industry use river water for cooling. Farmers irrigate their fields with groundwater, which in turn reacts to the river level. “In the next few years, the big dispute over water will begin. There simply won’t be enough for everyone,” says Haeberli. Less water in summer also means higher water temperatures, lower oxygen levels and a higher concentration of pollutants. According to Stahl, a prioritization of water use must now be developed. “There were hardly any such negotiation processes in our water-spoiled latitudes.” The developments are at least foreseeable. Forward-looking politics is now required.

The climate-related dangers in the mountains themselves are less predictable. Thomas Bucher, spokesman for the German Alpine Association, estimates that collapsing glacier towers, so-called séracs, open crevasses and rockfalls will become more likely in the coming years. Rock faces are losing their stability due to thawing permafrost, and at the same time glacial ruptures like this year on the Marmolada in the Dolomites are becoming more likely. Another source of danger are newly formed glacial lakes, for example when rocks and masses of ice fall into a lake from great heights.

And the fate of the glaciers themselves? Again, the models are pretty clear. In the next 30 to 40 years, a large part of the Alpine glaciers will probably disappear. They are simply too big for the current climate. However, the development up to the end of the century is not yet mapped out. That depends on the quantities of greenhouse gases that are still entering the atmosphere. When asked if there was hope for the German Alpine glaciers, Wilfried Haeberli replied, somewhat puzzled: “These last four can hardly be called glaciers today.”

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