VENICE, Italy – In the middle of the night, as the tide rose, an engineer in a command center on an artificial island on the rim of the Venice lagoon clicked an arrow on his screen reading, “Lift.”
Deep underwater, at the four mouths where the lagoon meets the sea, 78 giant walls fastened to the seafloor with hinges emptied themselves of water, filled with air and rose to the surface, where they held back the swelling sea.
Over the long November night, the city’s high-water forecasters drank coffee in an office by the Rialto Bridge, watching live feeds of 20-foot waves crashing on the other side of the walls. Eventually, the sea level outside the walls reached more than 5½ feet – the third highest in more than a century of records, a level that would normally risk lives, strand Venetians and tourists, and drown the economy.
Not this time. The city was drenched with rain but hardly a drop of seawater. MOSE, an Italian acronym for Experimental Electromechanical Module, evoking the biblical Moses, had parted the waters and saved the city.
“Without the walls, it would be a disaster,” said Alvise Papa, the director of the tide forecast center, who grew up rescuing merchandise from his father’s hat shop when high water shot up like fountains through cracks in the floor. “Instead, it’s normal life. Let’s thank the god of MOSE.”
Now, though celebrated as the city’s sentinel, MOSE may yet stand as a monument to the inexorable nature of climate change and the futility of man’s efforts to stop it. MOSE’s walls, costing 5 billion euros, about $5.3 billion, took so long to come together that the pace of climate change is outstripping the projections they were built to withstand.
After all of the effort to get the barriers up, the future challenge will be finding ways to keep them down. Venice is already using MOSE more than expected and faces the prospect of needing it much more than it had imagined against rising seas – so often that it would threaten to seal the city from the waters that are its lifeblood.
Its incessant deployment, experts warn, could render Venice’s lagoon a fetid swamp choked by noxious algae, turning the city’s charming canals into stinking open sewers.
Yet if the waters are not held at bay, there is little doubt that Venice will eventually be submerged and uninhabitable.
Today, Venice is safe, but it is staring at a future of excruciating trade-offs, with the sea level so high so often that the city will require constant protection.
“At that point, I must decide,” Papa said. “Do I save the city, or do I save the lagoon?”
The sinking city
Venice exists because of and despite the sea. Since its founding, water has both protected and threatened it. Venetians have always struggled to keep a balance between the two.
When refugees from the Italian mainland first settled on the mud flats and islets here in the fifth century, they built foundations with wooden piles in the sediment. They erected sea walls in white Istrian stone, impermeable to salt. They manipulated the lagoon to fit their needs. Their ingenuity built the Republic of Venice into a rich and strong maritime power.
In 1897, Venice began taking the measure of its enemy, establishing a reference mark for high water at the Punta della Salute entrance of the Grand Canal. In the first two decades of the 20th century, Venice had high tides above 110 centimeters, about 3 feet and 7 inches, only six times.
But the average sea level in Venice has risen nearly 1 foot since 1900. In the past 20 years, tides have exceeded 110 centimeters more than 150 times.
But it is not just that the seas are rising. Venice is sinking. The tectonic plates under the city are naturally settling, a process accelerated in the 20th century by the pumping of groundwater for use in the industrial port of neighboring Marghera.
From 1950 to 1970, Venice sank nearly 5 inches. The pumping has long stopped, but Venice still sinks about 2 millimeters a year.
In November 1966, a fatal flood of more than 6 feet hit, the worst measured. Water paralyzed Venice, destroying buildings and the already fragile sense of the city as a secure place.
Italy was confronted with a terrible question: Could Venice be saved?
An elegant solution
Acknowledging “general sea level rise,” Italy’s National Research Council held a competition in 1970 for companies to come up with proposals on how to rescue the city.
Ideally, it wanted walls that could open and close to stop high water while also allowing ships to pass and maintaining the natural exchange of waters between the sea and the lagoon.
Riva Calzoni, the Milan firm behind the winning idea, sketched sea walls that filled with air and floated up to meet the high tides and then filled back with water to lower again, a secure but nearly invisible defense that would cost less to maintain than a fixed, exposed structure.
But if the idea of MOSE was elegant in its simplicity, the reality was more complicated. The project would accompany Italy through the next half-century.
In 1984, the government subcontracted the building of MOSE to a consortium of major Italian companies and estimated that the walls would be put in place by 1995. It was not until 2003 that Prime Minister Silvio Berlusconi, a proponent of big public works, laid the first stone. The estimate then was that the project would be finished by 2011.
MOSE became a constant source of controversy and doubt. Over the years, a culture of secrecy, shady business practices and government corruption seeped into the project. In 2014, Venice prosecutors revealed a scheme to overbill the government and bribe politicians to keep the project and public money flowing. They arrested 35 people.
Afterward, from 2014 to 2018, public financing dried up as the state, loath to enable more graft, examined expenditures with extreme caution. Many businesses involved in the scandal folded.
Disaster foretold
On the night of Nov. 12, 2019, a sharp drop in temperature caused what Papa, the head forecaster, described as a never-before-seen “anomalous tropical cyclone.”
At its height, the tide hit more than 6 feet and flooded more than 85% of the city, killing two people and causing untold damage.
This was it, the big one that MOSE had been designed to stop. Engineers at the time said it was ready. But it stood down.
The failure to stop the great floods brought political pressure, international scrutiny and uncomfortable introspection to Venice and all of Italy. A change had to be made.
In the days after the flood, Mirco Angiolin, the site manager at the sea wall’s command center, lamented that the walls were ready but that no one was in charge to activate MOSE when it was needed.
“We need a chief,” he said.
Rome accelerated the appointment of Elisabetta Spitz, a top public-sector manager, as MOSE’s overseer.
She said she “made the decision” Oct. 3, 2020, to lift the walls – not to answer a crisis but as a simple test. With relatively little fanfare, the walls went up.
They worked.
Since then, Venice has been protected from high-water events, but the parts of the city that flood at lower levels remain precariously exposed.
The experts who had conceived MOSE estimated that the sea walls would need to be raised an average of five times a year to stop tides of about 3 feet, 7 inches. Since MOSE began functioning about two years ago, the walls have been raised 49 times.
On Monday, the Intergovernmental Panel on Climate Change, an authoritative body of experts convened by the United Nations, said the Earth was likely to cross a critical threshold for global warming within the next decade. According to their best estimate, the sea level in Venice could rise by nearly 2 feet by the end of the century.
At that rate, experts say the walls would need to be up more often than they were down. Combine that with the increasingly common violent winds and record rainfalls that push more water into the lagoon, and the walls may need to be raised nearly constantly.
Defenders of the sea walls expressed frustration with doomsday predictions about their effect in a century’s time, especially since MOSE has left Venice better defended than many other coastal cities.
Luigi Brugnaro, the mayor of Venice, has asked the government for another 1.5 billion euros over 10 years to help protect the city.
