The long read: Sea level rise, erosion and cruise ships are worsening Venices flood problem. But corruption nearly scuppered the solution
I was in Venice when the acqua alta struck on 28 October 2018. I noted in my diary: It happened today. The first big acqua alta of the year, with a siren at 09.17, followed by two steady tones. One tone is for 1.1 metres, two 1.2 metres, three 1.3 metres and four 1.4 metres or more. The tidal chart says the level should peak just after noon. At 12.30 I put on my green rubber boots. Stepping out along the canals, I found the water above my ankles and immediately had to re-learn how to walk. Walking at normal speed causes the water to splash over your boots and on to your legs. I slowed down, finding I also needed to watch out for little waves from the boats on the canal, which rode up right over the submerged pavement.
Tourists used bin bags or fluorescent pink plastic booties over their shoes, walked barefoot or just got their shoes wet. Judging by the laughs and picture taking, high water looked fun, but not for the tourists who held heavy suitcases to their chests to keep them dry as they walked. One woman, who had given up, was dragging hers through the water. They looked really stressed. People carried small dogs and children, while a man hefted an old woman on to one of the raised board walkways set up for pedestrians. Many shops are open, some with thigh-high flood barriers at the door, even as clerks mop up, pushing water out with wiper blades on sticks or setting up pumps to spew water back out on to the street. In a pizzeria, waiters shuffled through the water to serve customers.
By the time I got to St Marks Square, hip-booted policemen urged people on the walkways to move along and not to stop for selfies. The water in the square was too high for my boots, nearly knee-high, so it spilled over the top and poured in. Cold. The crowd in the square seemed to be enjoying the spectacle, even when it started to rain.
The next day, another acqua alta of 1.56 metres broke a record, flooding 75% of the city, giving Venetians a real scare, but now, a year on, that has paled in the face of a new record flood recorded on 12 November 2019, of 1.87 metres, the highest in more than 50 years, flooding over 85% of the city. Lesser record highs hit in the following days. The flood caused millions in damage, and two deaths one man who tried to restart a water pump was killed by electrocution, and another was found dead in his home. The extended flooding has disheartened many among the citys depleted population of 53,000, with some now thinking that there is no future for Venice.
But the threat from flooding has been growing for some time. The problem first came to global attention on 4 November 1966, with the record 1.94 metre acqua alta flooding 96% of the city. The city was unprepared, and waist-high, stinking, muddy, oily water destroyed housing, shops, goods and art treasures on all the islands and lagoon shorelines.
The catastrophe sparked an international outcry that led the Italian government to pass a special law in 1973, officially recognising that the fate of Venice and the lagoon that surrounds it need to be considered as one entity. This legislation aimed to turn back the environmental devastation of the last century. It promised to restore the lagoons physical and ecological integrity by rescuing the salt marshes, ending land reclamation and curbing pollution.
Faced with subsidence under Venice and the threat of bigger tides, the authorities planned gigantic dams to be constructed at the three openings where the lagoon meets the sea. In the decades since, another force has picked up that is much more threatening: sea-level rise. The Venice area is among the low-lying coasts of the world that, like the Netherlands, have been saved from the sea by human effort, via the use of dykes and pumping out water, and much of it is very sensitive to sea-level changes.
The average sea level rise predicted by the IPCC, the United Nations body for assessing climate change, is 0.43 metres by the end of the 21st century, and it could be as high as a metre or more. In Venice, higher water levels, adding to the effect of subsidence, are creating new, possibly unsustainable, stresses on the lagoon defences and the city. Already, higher water levels cause rising damp in Venices ageing walls, crumbling the bricks and rusting the ties that hold up the buildings. The effect of higher water is also aggravated by lagoon erosion. While the tides took between 90 minutes and two hours to enter a century ago, now they enter in an hour. With the lagoon an average of 1.5 metres deep, twice what it was, the tides not only rise higher but also move faster and in greater volume on entering and leaving. The number of acque alte have also been rising since the last century: the number of floods over 1.1 metres have doubled since the 60s, due not only to subsidence and sea level rise, but also to increase in wind, waves and storms related to the climate crisis.
Several decades after the laws intended to protect Venice came into effect, much has been accomplished, but the hopes they raised have taken a battering in the face of inaction, resistance and inertia.
The 1966 flooding disaster that led to special laws for Venice launched decades of studies and planning and opened a multibillion-euro tap of funding that would go into housing refurbishment, art restoration and a two-part programme to save the lagoon. One part dealt with acqua alta up to 1.1 metres by bolstering the shock-absorbing effect of the salt marshes and sea fronts while building smaller barriers and localised adaptations in Venice and on other islands. The other part, for flooding over 1.1 metres, when the sirens sound, envisioned the massive dams dubbed Mose (pronounced Mos), a strained acronym for Modulo Sperimentale Elettromeccanico (Experimental Electromechanical Module).
The word experimental was included in the barriers name in a nod to the laws requirement that the solution be gradual, experimental and reversible. This was because solutions to managing the lagoon have historically been found with an element of trial and error. In reality, however, the massive, bright yellow, semi-submerged barriers under construction since 2003 are built on a foundation of millions of tonnes of concrete fixed with enormous piles driven into the sea floor, with no room for changing of minds. Mose also refers to the biblical Moses who held back the tides in Egypt, allowing the Jews to escape the pharaoh which sets expectations rather high. So, the naming has not been a great boon, and already the flood gates have far surpassed their estimated cost, with more than 5.4bn spent.