There is no single date when Venice will completely disappear. Instead, the city faces a gradual increase in flooding frequency and severity as sea levels rise and the ground continues to settle. While the historic center is not currently underwater, it is at a critical threshold where minor changes in water level cause major disruption.
The two forces at play
Venice is under pressure from two distinct directions. The ground itself is sinking, known as subsidence, while the Adriatic Sea is rising. These two factors combine to create relative sea-level rise, which determines how often and how deeply the city floods.
Why the ground is sinking
The historic center sinks at a rate of roughly 1 to 2 millimeters per year. This is caused by the heavy weight of the city compressing the soft mud beneath it. In the mid-20th century, this process accelerated significantly when industrial pumping removed groundwater from aquifers under the lagoon. Although this pumping stopped in the 1970s, the soil continues to settle slowly. In other parts of the lagoon, particularly salt marshes, subsidence can be faster, reaching 4 to 6 millimeters per year.
Why the sea is rising
Global sea levels have risen by more than 30 centimeters since 1870. This is driven by the melting of glaciers and the thermal expansion of warming oceans. Because Venice is so low-lying, this rise means that high tides now reach higher points in the city than they did for previous generations. What was once a rare, severe event is becoming a regular occurrence.
How vulnerable is the city?
More than half of the historic center lies between 0.80 and 1.20 meters above mean sea level. The lowest point in the city, the paving of St. Mark’s Square, sits only 55 centimeters above the average water level. Local tidal ranges can reach one meter, leaving very little margin for error.
When sea levels rise by just 10 centimeters, the frequency of flooding increases dramatically. In November 2019, water levels surged to 187 centimeters above the local datum, inundating over 80 percent of the historic center. This level of flooding causes severe damage to porous brick and marble, as saltwater seeps into the stone and crystallizes, causing it to crumble over time.
The role of the MOSE barriers
To combat these floods, Italy installed the MOSE system. These are 78 massive steel gates located at the three inlets of the lagoon. When a high tide of 110 centimeters or more is predicted, air is pumped into the gates, causing them to rise and block the sea. The system has successfully prevented many catastrophic floods since its operation began in 2020.
However, MOSE is not a permanent solution. It is a stopgap measure. As sea levels continue to rise, the barriers will need to be closed more frequently. If they are closed too often, the lagoon becomes stagnant. This traps waste, harms the local ecosystem, and disrupts commercial shipping. Engineers warn that without further adaptation, the barriers will eventually be insufficient to keep the city dry during daily tides.
What happens by 2100?
Projections suggest that by 2100, global sea levels could rise by 40 to 80 centimeters or more, depending on carbon emissions. Under high-emission scenarios, a significant portion of the historic center could be submerged during regular high tides. The city would not vanish overnight, but it would become increasingly difficult to inhabit and maintain. The focus is shifting from preventing total submersion to managing chronic flooding and preserving the remaining structures.