Colleen Barry | Associated Press
VENICE, Italy – After hitting the second largest flood in its history in November 2019, Venice was flooded with four more exceptional tides over a six-week period, shocking Venetians and raising fears about the worsening impact of climate change.
The repeated incursion of the lagoon’s brackish water into St. Mark’s Basilica this summer is a quiet reminder that the threat has not gone away.
“I can only say that in August, a month when it never happened, we had tides of more than a meter five times. I’m talking about August when we’re calm, “San Marco Carlo’s chief superintendent, Alberto Tesserin, told The Associated Press.
The unique relief of Venice, built on stilts among canals, made it particularly vulnerable to climate change. Rising sea levels increase the frequency of high tides inundating the 1,600-year-old Italian lagoon city, which is also gradually sinking.
It is the fate of coastal cities such as Venice that climate scientists and world leaders gathered in Glasgow, Scotland for the UN climate conference starting October 31, will be thinking about.
The worst-case scenario for sea level rise by the end of the century in Venice is an astounding 3 feet 11 inches, according to a new study published by the European Union of Earth Sciences. This is 50% higher than the worst global average sea level of 2 feet 7 1/2 inches predicted by the UN science team.
The interplay of the city’s canals and architecture, natural habitat and human ingenuity has also earned it recognition as a UNESCO World Heritage Site for its Outstanding Universal Value, recently threatened by over-tourism and cruise ships. traffic. It was not listed as endangered after Italy banned cruise ships from passing through the San Marco Basin, but alarm bells are still ringing.
The Basilica San Marco, located at the lowest point in Venice, offers a unique location to observe the impact of rising sea levels on the city. The area outside is flooded about 30 inches, and water flows through the narthex into the church by 34.5 inches, which has been strengthened from the previous 25.5 inches.
“Conditions continue to deteriorate since the floods in November 2019. Therefore, we are confident that floods are no longer an accident during these months. It’s a common occurrence, ”said Tesserin, whose honorary title of First Prosecutor of San Marco dates back to the ninth century.
Venice has experienced almost as many floods over the past two decades at over 1.1 meters – the official level for acqua alta, or “flood” caused by tides, winds and lunar cycles – as in the previous 100 years: 163 versus 166 according to city data.
Exceptional floods over 4’7 ” are also accelerating. This mark has been reached 25 times since Venice began keeping such records in 1872. Two-thirds of them were registered in the last 20 years, and five, or one-fifth of the total, from November 12 to December. 23, 2019.
“What is happening now is constantly changing for the Venetians, who have always lived with periodic floods,” said Jane Da Mosto, executive director of We Are Here Venice. “We live with floods that are becoming more frequent, so it worries me that people have not yet realized that we are in a climate crisis. We already live by this. We are not talking about plans to fight this in the future. We need to have ready-made solutions for today. “
Defending Venice has been entrusted to Moses, a nearly $ 7 billion project that, after decades of cost overruns, delays and a bribery scandal, is officially still in testing.
Following the devastating 2019 floods, the government of Rome put the project under ministry control to expedite completion, and last year began activating barriers when a 4ft 3in flood looms.
Since October 2020, barriers have been raised 20 times, saving the city from a season of severe flooding, but not from the increasingly frequent tides.
The extraordinary commissioner, Elizabeth Spitz, maintains the strength of the underwater barrages despite fears by scientists and experts that their usefulness could be exceeded for decades due to climate change. The project was again postponed until 2023, and an additional $ 580 million was spent on “improvements,” which Spitz said will ensure its long-term effectiveness.
“We can say that the effective life of Moses is 100 years with the necessary maintenance and interventions to be implemented,” Spitz said.
Paolo Vielmo, the engineer who wrote the expert reports for the project, points out that sea level rise was projected to be 8 1/2 inches when Moses was first proposed more than 30 years ago, well below the current worst results from UN scientists. cover script 80 centimeters.
“This puts Moses out of sight,” he said.
According to current plans, the Moses barriers will not be raised 3 feet 7 inches for flooding until the project receives final approval. This leaves San Marco unprotected.
Tesserine oversees the work of protecting the basilica by installing a glass wall around its base that will ultimately protect the swampy lagoon water from seeping inward, where it deposits salt that corrodes marble columns, wall cladding and stone mosaics. The project, which is still interrupted by the tides, was due to be completed by Christmas. Now Tesserine says they’ll be lucky to finish it by Easter.
Regular tides elicit a dismal reaction from Venetians, who are used to carrying rubber boots at every flood warning, and a delight among tourists, fascinated by the sight of the golden mosaics and the domes of San Marco reflecting in the rising waters. But businesses in Piazza San Marco are increasingly seeing themselves at the epicenter of the climate crisis.
“We have to help this city. It was a light for the world, but now it needs the whole world to understand it, ”Annapaola Lavena said, protruding from the metal barriers that kept water up to 3 feet 5 inches from invading her marble-floored cafe.
“Acqua alta is deteriorating and this is completely blocking the business. Venice lives on thanks to its artisans and tourism. If there is no more tourism, Venice will die, ”she explained. “We have a great responsibility in trying to save him, but we are suffering a lot.”