Last week, 186 passengers had to be evacuated from the cruise ship Viking Ullur, after it ran aground on a sandbank in the Danube. Others have been left stranded, unable to move between Vienna and Budapest. Passengers stood on deck, the Habsburg splendour around them out of reach as the river fell to 41cm in Budapest, within 8cm of its 2018 all-time low. Elsewhere on the Hungarian stretch of the river, new record lows were recorded.

Farther east in Romania, the Danube recorded its lowest water levels since 1996. A river’s flow is measured in cubic metres per second, and at Baziaș, where the river enters the country, it stood at 1,700m³/s, against a July average of 4,700m³/s. Ferry services were suspended, as were grain barges.

While providing the most glamorous images, the Danube is just one of the major rivers veining through Europe that has been suffering through this summer’s drought. Farther north, the Rhine, perhaps the most vital fresh-water transport route in the continent, broke its own records, with levels at Kaub dropping to about 40cm, the level at which shipping runs in emergency mode, with barges loading as little as a fifth of normal capacity.

The extent and frequency of these summer droughts has surprised even the most pessimistic expert observers. In 2018, Germany’s weather service designated that year a Jahrhundertsommer – a once-in-a-century summer – as the Rhine spent 132 days at low water. “The events of 2018 can’t be allowed to be repeated,” said Andreas Scheuer, then the federal transport minister. But they were.

In 2022, EU scientists........

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