In Venice, the barriers against high water were active 28 times in 2024 compared to 25 the previous year. Alvise Papa (Centro Maree): “The number of tides above 80 centimeters keeps increasing”
By Eugene Pendolini
Jan. 11, 2025
Venice will have to close its gates to the tide more and more often. Driven by the irrefutable fact of rising sea levels due to climate change, scientists’ predictions are becoming reality, year after year.
Data from 2024
Just compare the data from the last twenty-four months: MOSE was raised 25 times in 2023, 28 in 2024, therefore three more, part of a progressive growth. Overall, to date the number of times that the Mose has saved the city from high water since 2020 is approaching 100. We are at 97, for a total cost of almost 20 million euros.
Ninety-seven days that the city was spared from the difficulties of flooding on one hand, and on the other of inconveniences to the Port and its operators, in this perennial dualism between the needs of commercial operators and environmental protection.
However, for Alvise Papa (who is responsible for the Municipality’s Tide Forecasting and Reporting Center) there is another piece of data, beyond the number of times MOSE is raised, to keep under control and which certifies the inevitability of the situation. “Let’s not forget,” explains the expert, “that the procedures for raising the dams are still provisional, and that over the years various things have changed, such as the moment at which the decision to raise them must be made. The mechanism, in short, is linked to a human activity that has undergone changes. While the real problem is the one linked to the activity of nature.”
Tides Above 80cm Increase
Nature, given the data we have in hand, has expressed itself with dramatic clarity in these years. In 2024 there were 219 events greater than or equal to 80 centimeters (taking into account the closures of the MOSE) recorded, more than ever before in history. If 2023 was the year of surprises, with high water even arriving out of season, in the middle of summer for several consecutive days, records were made in the year that just ended.
It is enough to consider that there were 186 events above 80 centimeters in total in 2023. This is a figure that is much more worrying than the three additional closures of MOSE in the last year. The much-feared rise in sea levels, which is estimated to rise by 30 centimeters by 2050, is already visible. Twenty years ago, the difference between high and low tide was 23 centimeters, and just last year it was 31: today it is 45 centimeters. In the early 2000s, the astronomical tide was 67 centimeters, today it is 87. This, by extension, means that lighter precipitation is enough to raise the average tide level which, consequently, has a more significant impact.
At the same time, a record was recorded for staying above 80 centimeters: almost 800 hours at sea. The average level is also the highest in history with 40 centimeters in Venice and 43 at sea. In 2024, there were no low tides lower than -50cm.
“Furthermore,” adds Papa, “comparing the average values of the decade around 2000 and the decade around 2020 we find that the amount of time sea levels remain above 80 cm has gone from an annual average value of 224 hours to 482 hours; the number of tidal events greater than or equal to 80 cm has gone from average values of 75 per year to 126, if we consider only the last 5 years the values are even higher marking a probable acceleration of the phenomenon, among other things documented in the scientific literature.”
How long will MOSE last?
This leads to an inevitable series of questions: how long will MOSE be enough to protect Venice? Is the city destined to remain closed for increasingly prolonged periods? This aspect was also touched upon in recent months by the Nobel Prize winner for water, Andrea Rinaldo, who, in a public meeting in Mirano as part of the Water Festival, made an estimate regarding the raising of MOSE which, he reiterated, arrived 60 years late: given current forecasts and future scenarios, for Rinaldo the floodgates will have to be raised 260 days a year.
In the meantime, however, all that remains is to deal with the current situation, starting with the economic data. Based on the estimate that the cost of each raising of MOSE is (today) around 200 thousand euros, the total calculation is easy to do: around 19.5 million euros. A sum calculated by default, given that the last few years have been used to perfect the machinery and to reduce the operating costs of the mega-project.
The coexistence of MOSE and the Port
The other big issue, destined to become increasingly urgent while waiting for the Malamocco navigation lock, is the coexistence between MOSE and the Port. With each raising of the floodgates at the mouths of the Port, the operators do not miss the opportunity to denounce the limitations to the operations of the Venetian port and to ask for clarity and greater involvement in the operational management of this massive mechanism to defend the city.
Source: La Nuova di Venezia e Mestre
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