When the Mose rises, Venice buys time. But that time has an expiration. A study published on April 16, 2026 on Scientific Reports it lines up the adaptation scenarios of the city and the lagoon up to 2300 and arrives at a very clear conclusion: the mobile barrier still protects Venice today, however the rising sea is already pushing towards harder, more expensive and much more invasive choices, to the point of contemplating the moving of monuments towards the hinterland and the abandonment of parts of the city.
Within this reasoning, Venice remains inseparable from its lagoon, and here the real fracture opens up. The floodgates at the three port inlets defend stone, houses and calli, but any longer closure reduces the exchange of water with the Adriatic, complicates the quality of the water, weighs on the ecosystem, the port and the lagoon morphology. There’s also another pressure in the background: a 2023 study linked the severity of some historic high waters to changes in atmospheric circulation, adding another element to an already precarious balance.
The first crossroads comes well before the next century
The authors work with the concept of adaptation tipping points, the points at which a defense stops doing its job and forces a change of scale. With additional measures, the current system can handle up to about 1.25 meters of relative sea rise; already around 50 centimeters the heaviest options come onto the table, and in a range between 0.75 and 1.75 meters the transition to a transformative phase becomes inevitable. Translated: Venice still manages to adapt for a while, then the season begins in which every solution saves something and lets something else go.
The route of the ring dams would envelop the historic center and other settlements with dedicated embankments, leaving the lagoon open towards the sea. That plan includes efficient sewerage, permanent pumps and a city that needs to be rethought in terms of transport, services and even the daily perception of risk. Estimated costs range from 500 million to 4.5 billion euros, with other costs for the pumping systems. The advantage lies in the protection of monuments, homes and most economic functions. The price lies in a physical and cultural caesura: Venice would continue to be in the water, with a much colder and more artificial relationship with its lagoon.
The closed lagoon road moves the technical bar even further. Here the lagoon would be transformed into a kind of coastal lake regulated by permanent dams at the harbor inlets, rises on the barrier islands and new defenses along the external margin. On paper this architecture can protect Venice from up to 10 meters of sea rise. An even more extreme version, the super levee, a very wide barrier designed for exceptional events, would further raise the threshold. The bill would exceed 30 billion euros and the lagoon, as a living environment, would change its skin irreversibly. The dry city, the monumental fabric, a part of urban life would remain. The ecological system that has shaped that city for centuries would disappear.
Each solution defends a piece of Venice and leaves everything else exposed
Then there is the word that until now seemed inadmissible and which enters the study without any loose ends: withdrawal. The authors place it above 4.5 meters of sea rise, a scenario associated with the period after 2300. In that framework there is talk of relocating selected monuments, moving residents, allowing part of the city to be abandoned. The comparison used to understand the scale of the problem goes through Abu Simbel, dismantled and reassembled in Egypt in the 1960s: an immense operation at the time, tiny compared to Venice. Economic estimates fluctuate a lot, and in the summaries released by the team they reach up to 100 billion euros. The hardest point remains another: what survives in a new site are precious fragments, while the historical body of the city, the lagoon culture and a large part of the economic activities are lost along the way.
The economic issue is already weighing heavily now. The existing defense system cost around 6 billion euros. Future works would require much higher sums and above all long times: 30-50 years to design, authorize and build the large infrastructures that enter into these scenarios. This is why the work insists on the political window that is narrowing. Lower emissions also keep sea flow lower on a secular scale; high emissions anticipate scale jumps and make transitions more abrupt. The city, essentially, must decide well in advance what type of injury it considers bearable.
The study avoids crowning a perfect solution. It brings together heritage, work, resident safety, port, tourism, ecosystems, traditions, and shows that a single optimal strategy does not exist. Venice thus becomes a cruel laboratory for the rest of the world too: the low-lying coastal areas adapt for a while, then reach the point where defense stops being a correction and becomes a transformation of the place. The same authors broaden the discussion beyond the Venetian lagoon and recall that all inhabited and low-lying coasts should immediately start thinking about the long-term implications of rising seas. The margin is shortening. And Venice, this time, will have to decide before water.
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