The Italian city of Venice faces the risk of being completely submerged within the next three centuries due to rising sea levels caused by climate change, in addition to the fact that the land on which the city stands is slowly sinking
In the past 23 years alone, the city has experienced 18 devastating floods that submerged more than 60% of its streets and canals, despite the presence of movable barriers installed in 2022 at a cost of €6 billion. However, scientists insist that these measures are insufficient and that the future requires more radical solutions.
Therefore, an international team led by oceanographer Piero Leonello studied four scenarios for protecting the city, ranging from continuing with the current fortifications to abandoning the city entirely.
Option 1: The "Open Lake" strategy – the current solution, but it is temporary.
This strategy relies on closing the entrances to Venice's lagoon with movable barriers whenever sea levels rise to a flood-prone level. Its implementation has cost approximately $7 billion so far, but it is better than doing nothing at all. However, climate models indicate that these barriers will become completely ineffective once sea levels rise by 1.25 meters, a figure likely to be exceeded by 2300 even under low-emission scenarios.
Even more concerning is that frequent closures of the barriers increase the likelihood of their malfunction or delayed operation, threatening the safety of residents and historical landmarks. If the closures continue for several consecutive days, the city will require a massive wastewater treatment system to prevent water stagnation in the lake.
In this scenario, Venice's main islands are surrounded by circular barriers up to 3 meters high, completely isolating the city from the turbulent waters of the lagoon outside.
These dams could provide effective protection even if sea levels rose by 6 meters, a significant safety margin compared to the previous option. However, the price would be the city losing its direct connection to the lake's ecosystem, negatively impacting its cultural heritage and unique tourist appeal. Scientists estimate the cost of this project at between €0.5 and €4.5 billion, making it a relatively moderately priced option. But the team warns that projects of this scale can take up to 50 years to complete, necessitating immediate planning.
Option three: Completely closing the lake – maximum protection but at a high price
This option involves raising the level of the natural barrier island and constructing permanent dikes up to 5 meters high at all lake entrances, effectively turning the lake into a completely enclosed body of water. This solution is particularly effective at protecting the city from sea levels rising up to 10 meters, making it the safest option in the long run.
It would preserve historical monuments, residential buildings, and the tourism sector, but would completely destroy the lagoon's natural ecosystem, which has shaped the city's identity throughout history. This scenario would also mean the end of Venice as a functioning seaport and would require the installation of a permanent pumping system to prevent water from stagnating and fetiding within the enclosed lagoon. The estimated cost of this project is at least €30 billion, making it one of the most expensive options
Option three: Completely closing the lake – maximum protection but at a high price
This option involves raising the level of the natural barrier island and constructing permanent dikes up to 5 meters high at all lake entrances, effectively turning the lake into a completely enclosed body of water. This solution is particularly effective at protecting the city from sea levels rising up to 10 meters, making it the safest option in the long run.
It would preserve historical monuments, residential buildings, and the tourism sector, but would completely destroy the lagoon's natural ecosystem, which has shaped the city's identity throughout history. This scenario would also mean the end of Venice as a functioning seaport and would require the installation of a permanent pumping system to prevent water from stagnating and fetiding within the enclosed lagoon. The estimated cost of this project is at least €30 billion, making it one of the most expensive options
The last and most extreme option is to evacuate Venice completely, moving its residents, monuments and historic buildings to another location, and abandoning the floating city forever.
This task will be both monumental and heartbreaking, as it means ending the story of a city that has stood above the water for over 1,600 years thanks to millions of wooden stilts. The cost is also enormous, estimated at around €100 billion, including the relocation of historical sites and compensation for residents forced to leave their homes. This decision will also mean allowing the lake's ecosystem to succumb to deeper, saltier waters resulting from rising sea levels, with potentially far-reaching environmental consequences.
Although this option seems far-fetched now, scientists emphasize that in the worst-case emissions scenarios, other strategies may become ineffective before the end of this century
Policymakers and Venetians face a complex balancing act between the high costs of conservation, preserving the unique cultural identity, and protecting the lagoon's ecosystem. The scientific team believes that ring dams or closing the lagoon are the most realistic options at present, but either requires immediate planning, as such large-scale projects take decades to complete.
Researchers emphasize that, given the global failure to adequately reduce greenhouse gas emissions, considering radical transformations for the city is no longer a luxury but an urgent necessity. They warn that if the current situation continues, the "open lagoon" strategy may become unviable before the end of this century, leaving Venice effectively unprotected from an ever-rising
