Throughout history, Venetians have learned to live with high tides, known as acqua alta. But now, climate change is taking its toll on the ancient city, with flooding increasing in both frequency and intensity. Massive barriers, which temporarily separate the Venetian lagoon from the sea, have been designed to fend off the water. But they have also raised a difficult question: should Venice save itself or the lagoon’s fragile ecosystem?
The second-highest tide on record
In a city normally teeming with tourists, Andrea Turchetto is a rare breed: a true Venetian, born and raised in the floating city. Unlike other locals, he still calls it home. His glass bead business is based at the heart of Venice, in the Cannaregio district.
Andrea was six years old in 1966, when the city experienced its highest tide on record. In 2019, history repeated itself and he witnessed the second most devastating episode of the so-called acqua alta.
But this time, it was different. Authorities had originally warned that the tide would not exceed 1.3 metres, he explains. Later that night on November 12, it rose to 1.87 metres, with gusts of wind reaching 110 km per hour.
"It all happened so fast," he recalls. "There wasn't enough time to save everything."
There is anger in Andrea’s voice, directed at the politicians and local authorities who could have prevented such a disaster from happening.
"There was negligence," he says. "It's not an issue of climate change, something didn't work out as it should have."
A city submerged by rising sea levels
Scientists, though, are unequivocal: climate change is partly to blame.
The acqua alta is indeed a natural phenomenon, provoked by a combination of high tides, strong winds and variations in the atmospheric pressure. An increase in their frequency and intensity, however, is the result of a warming, changing climate.
Out of the top ten tides, five have occurred in the last 20 years; a sign that the phenomenon is accelerating. Given Venice's unique setting – a constellation of 100 islands – and the fact that the ground underneath it is sinking, the city could very well vanish underwater within a century.
MOSE, Venice's controversial floodgates
To stay afloat, Venice has erected a set of floodgates with a biblical name: MOSE, Italian for Moses. It’s an acronym that stands for Modulo Sperimentale Elettromeccanico or "Experimental Electromechanical Module".
Elena Zambardi, spokeswoman for Venice's Consorzio Venezia Nuova, describes it as "a very special work of engineering, quite extraordinary".
The barriers are "invisible", lying underwater when they are not in use, only to emerge when they need to be activated. The yellow floodgates can protect the city from tides of up to 3 metres, according to local authorities.
For Venetians, seeing the barriers rise for the first time in 2020 was a huge relief. The €6 billion billion project had crystallised the anger felt by many at the government's slow response to a problem that existed long before climate change entered the global lexicon.
MOSE was designed in 1984 but was stalled by corruption and cost overruns. After the 2019 acqua alta, the government came under pressure to finally finish its construction.
In service but already obsolete?
One of the main criticisms against MOSE is that it's already outdated in today's climate reality.
In the middle of the Adriatic Sea, 15 kilometres from Venice, scientists from the Institute of Marine Science (ISMAR) keep tabs on rising sea levels. The oceanographic tower is equipped with all kinds of instruments to track any variations in wind speed, wave height and water temperature.
The tower was built just after the acqua alta in 1966. Back then, the view was that science could save Venice. More than half a century later, the city is still at risk from disappearing under rising seas.
According to Georg Umgiesser, an oceanographer at ISMAR, one thing they know for sure is that rising sea levels are here to stay. MOSE, on the other hand, won't be able to handle it.
"If you have a sea level rise of 50 cm you will basically be forced to close the MOSE once a day," he explains, adding that the mobile barriers have raised a difficult question.
Georg believes that in the future they might have to be activated 300 to 400 times a year, effectively separating the Venetian lagoon from the Adriatic Sea. The exchange of water between the two, however, is vital for the health of the lagoon. Is the latter doomed to disappear?
"We want to save Venice. What Venice? Do we want to save the lagoon? Or do we want to save the city?" he wonders. "If we want to save the city, at a certain point I think we are forced to close the lagoon."
Still, officials dismiss the criticism, saying MOSE is the best course of action to safeguard the ancient city.
No Venice without lagoon, no lagoon without Venice
Jane da Mosto is not ready yet to give up on the lagoon: "More than anything, Venice is its lagoon," she tells us.
As the Executive Director of "We are Here Venice", she has been a strong advocate of protecting the lagoon and its saltmarsh.
"The marshlands perform a variety of functions," she says. Acting as a natural barrier to the acqua alta is one of them, attenuating the tides and slowing down the currents.
Most wetlands around Venice have now disappeared, with global warming, pollution and urbanisation contributing to their rapid decline. Only one sixth of the saltmarsh in the lagoon has been left intact, according to recent estimates.
Restoring them has become ever more important, as the city’s survival is at stake. Jane is convinced that "more saltmarsh will protect Venice from more chronic water levels".
Of course, the boggy ground won’t save the ancient city from collapsing, but Jane regrets that local authorities haven't done enough to take the marshland seriously as a solution to Venice's problems.
As to the "Venice vs. lagoon" dilemma, it's just not an option on Jane’s mind: "There isn't a choice," she concludes. "I insist that both the saltmarsh and Venice are looked after for the future."
