Book review: a Swiss glaciologist celebrates the transient icebergs on a mountain lake and explains why they matter.All across the Alps, glaciers are slumping into lakes and pools of their own meltwater. A typical example is the little glacier at the top of the Geren Pass, a windy gap in the ridgeline above Switzerland’s Bedretto Valley. A crescent-shaped lake formed at its foot at the start of this century, and has been expanding ever since, eating steadily into the remaining ice-field.
In November 2020, however, something different happened here. As winter comes early at 2,670 metres, the lake had already frozen over by the 26th of the month. Unfortunately, nobody was watching on or around that day when, probably within a few minutes, huge blocks of the former glacier erupted upwards, smashing their way through the surface ice or rafting it high into the air.
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The lake on the Geren Pass in September 2020. Image by courtesy of Alpine Light & Structure |
What had happened? Within a few weeks, a curious researcher, Giovanni Kappenberger, had skied his way up to the pass to find out. Few could be better qualified to do so. As Kappenberger’s family and given names suggest, his life has spanned the very same Italian and German-speaking regions that the Geren Pass links together. He was born in Italian-speaking Lugano in 1948, but studied natural sciences at Zurich’s Federal Institute of Technology (ETH). While working as a meteorologist for the next few decades, he also kept up his interests in glaciology by helping to monitor the mass balance of the Basodino glacier, Ticino’s largest expanse of ice.
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The lake after the "evento catastrofico" of November 2020. Image from Giovanni Kappenberger: Die Eisberge am Gerenpass |
Arriving at the Geren Pass, Kappenberger saw a new chaos of giant ice blocks crowded into the small lake. This couldn’t be a normal “calving” from the end of the glacier, as in other lakes. Instead, he deduced that some kind of “evento catastrofico” was responsible.
Back at the nearby Piansecco hut that evening, he sketched out what must have taken place. The rising lake had progressively submerged the glacier’s tongue over a number of years until the warm summer of 2020 loosened its grip on the rock below, letting the ice break free and float to the surface. And this event was the starting point for Kappenberger’s book,
Die Eisberge am Gerenpass: Poesie des Eises (The icebergs on the Geren Pass: Poetry of the ice), published two years later.
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Kappenberger's sketch of the "evento catastrofico" that created the new icebergs. Illustration from Die Eisberge am Gerenpass |
Visitors to the pass could now see an extraordinary throng of icebergs jostling each other amid a frozen sea – and thanks to the lake’s low rim, this foreground was set against a backdrop of the Bernese Oberland’s highest peaks, some twenty or thirty kilometres distant. Kappenberger’s next move was to name the largest ice-blocks – Olaf, Irene, Central and so on – so that they could be more conveniently documented. And then he and his colleagues set to work to measure, monitor and record the lake, its water levels, flow rates and its unique icebergs.
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The book's back cover with watercolour by the author. |
Or perhaps not quite unique. A submerged glacier tongue has broken free on more than one occasion elsewhere in the Alps, although usually with unspectacular results, as Kappenberger notes. But the icebergs of the Geren Pass were uniquely massive. This they owed to the unusual thickness of the parent glacier, as revealed by a survey with ice-penetrating radar in March 2021.
Between December 2020 and October 2022, Kappenberger made fifteen visits to the Geren Pass. The surveys he and his colleagues undertook, particularly on the lake’s water levels, are summarised in his book, which appeared first in Italian and then in German.
But the researchers also took the time to enjoy and commemorate the scenery in a generous array of photos and even a watercolour or two. Poems too punctuate the narrative, including verses by
Kenneth White (1936-2023), the founder of geopoetics. Kappenberger is delightfully multidisciplinary in his approach, amply justifying the subtitle he gave his book: “Poesie des Eises” (poetry of the ice).
In July 2021, the scientists were even joined by a swimmer who took a dip amidst the icebergs to raise funds for an “IceSwim4Hope” charity. But how much hope is left for the ice on the Geren Pass? The icebergs are already on their way to oblivion – only a few still show their backs above the water at the time of writing – and the glacier’s days too are numbered. Up to 2021, Kappenberger gave it twenty more years of existence; after the ferocious summer heat in 2022, he cut that estimate in half.
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The lake in October 2024: few icebergs have survived. Image by courtesy of Alpine Light & Structure |
After a decade or two, visitors to the Geren Pass will see only a little round lake. The shape, though not the size, may remind some of the great basin of the Arctic Ocean. Kappenberger is on familiar terms with the High North, having spent two summers in the Canadian Arctic back in the 1970s, studying the Laika Glacier while curious polar bears looked in at the window of his hut. And in the last pages of his book, he draws the parallels between the Arctic seas and the Swiss glacier lakes.
As Kappenberger notes, the Arctic sea ice is shrinking fast, just like its alpine analogue. Once that insulating cover goes, the sun’s energy will beat down on the ocean to even greater effect, further lessening the temperature difference between the Arctic regions and everywhere else. This will weaken the jetstream, causing it to meander more widely (in so-called Rossby Waves) and reinforcing the blocking high or low pressure zones that bring droughts or flooding in their wake.
That outlook may be depressing – especially if we fail to respond to it – but Kappenberger’s approach is far from depressive. In the prologue, he writes that his efforts to document the icebergs’ brief existence and to understand the underlying dynamics seemed to be the best way of celebrating their beauty. It was like this, he suggests, reaching for a parable:
A man walking through a field happened on a tiger. Pursued by the beast, he ran away. When he came to a cliff, he grabbed the roots of a wild vine and lowered himself into the abyss. The tiger gnashed its teeth at him from above. Terrified, the man looked downwards, where he saw another tiger waiting to devour him. Only the wild vine protected him from that fate, and now he saw a couple of mice starting to gnaw at its tendrils. Just then, the man saw a strawberry growing next to him. With one hand, he kept his hold on the vine root and with the other he plucked the strawberry from its stem. My, how sweet it tasted…
Neither this parable or the book itself will appeal much to readers of a denialist persuasion. On the other hand, for those who like their hard scientific facts leavened with a dash of Latin wit, charm and aesthetic flair, Kappenberger’s slim volume is bound to taste sweet.
ReferencesGiovanni Kappenberger,
Die Eisberge am Gerenpass: Poesie des Eises, Unterstalden: rottenedition, 2022 (German edition, 203 pages, fully illustrated, translated from the original Italian text). The review copy was sourced from Zurich's specialist mountain book store,
Piz Berg und Buch.