Climate change is not the direct cause of high water in Venice. But it will contribute to making the phenomenon increasingly frequent and intense.
Almost the entire city flooded. Shops, homes, hotels, works of art, monuments. And then vaporetti and motorboats sunk, theatres and schools closed, tourists fleeing. The damage caused by the exceptional high-water event in Venice is incalculable. And while experts from the Ministry of Cultural Heritage are awaited to assess the damage suffered by the Basilica di San Marco, questions are being raised about the causes of the disaster and the possible role of climate change.
Let us start with the data. At around 11pm on 12 November, high water reached 187 centimetres at certain points in the lagoon city: a figure confirmed by Mayor Luigi Brugnaro. A level just below the exceptional high water of 4 November 1966, when the tide reached 194 centimetres. An event that caused the sea to submerge more than 80 per cent of the city.
What must therefore be distinguished is, on the one hand, the specific situation at the time; and on the other, the broader consequences of climate change. The event of 12 November can in fact be traced back to a series of contributing factors: "The situation in Venice," Bernardo Gozzini, a climatologist at the National Research Council (Cnr), explained to ANSA, "was determined by the combination of two phenomena: the strong sirocco winds, with gusts of up to 100 kilometres per hour blowing across the whole of the Adriatic, combined with the astronomical tide." The latter determines the rise in sea level based on the position of the Moon in its orbit around the Earth.
According to the expert, the situation cannot therefore be attributed directly to climate change. French meteorologist Guillaume Woznica, however, points out that "the climate nonetheless plays a role, as it risks exacerbating the high-water phenomenon in the coming decades. This is due to rising sea levels, projected at around 2–3 millimetres per year." This rise stems from the melting of glaciers and polar ice caps, a consequence of the increase in average global temperature.
This means that Venice must prepare to face an increase in the magnitude and frequency of events such as that of 12 November. "This is what emerges from any modelling," hydrology expert Emma Haziza confirmed, "in the Mediterranean basin. And it should be remembered that the intensity of cyclones will also increase in a generalised way." And therefore of windstorms.
Such as storm Vaia, which on 29 October 2018 blew at over 200 kilometres per hour and struck the entire Triveneto region and part of Lombardy. A phenomenon also caused by the unusually high temperature of the Adriatic Sea, whose energy was unleashed on land across 42,800 hectares, felling thousands of trees.
