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VENICE, Italy (AP) – After Venice suffered the second heaviest flood in its history in November 2019, it was inundated by four more extraordinary tides within six weeks, which shocked the Venetians and raised fears about the worsening effects of climate change.
The repeated infiltration of brackish lagoon water into St. Mark’s Basilica this summer is a silent reminder that the threat has not passed.
“I can only say that in August, a month in which that never happened, we had floods of over a meter five times. I’m talking about the month of August when we are quiet, ”Carlo Alberto Tesserin, the chief administrator of St. Mark’s, told The Associated Press.
Venice’s unique topography, built on wooden piles between canals, has made it particularly vulnerable to climate change. Rising sea levels increase the frequency of floods that inundate the 1600 year old Italian lagoon city, which is also gradually sinking.
It is the fate of coastal cities like Venice that will preoccupy climate scientists and global leaders meeting in Glasgow, Scotland for a UN climate conference that begins October 31st.
Venice’s worst-case scenario for sea level rise by the end of the century is a staggering 120 centimeters (3 feet, 11 inches), according to a new study by the European Geosciences Union. That’s 50% higher than the UN’s scientific panel worst-case average for global ocean rise of 80 centimeters (2 feet, 7 1/2 inches).
The interplay of canals and architecture, natural habitat and human ingenuity has also earned the city recognition as a UNESCO World Heritage Site for its exceptional universal value, a designation that has recently been jeopardized by the effects of overtourism and cruise lines on traffic. It escaped the endangered list after Italy banned cruise ships from passing through St. Mark’s Basin, but the alarm bells are still ringing.
Sitting at the lowest point of Venice, St. Mark’s Basilica offers a unique position to monitor the effects of rising sea levels on the city. The piazza outside floods 80 centimeters (about 30 inches), and water flows 88 centimeters (34.5 inches) into the church, which has been reinforced from 65 centimeters (25.5 inches) previously.
“The conditions have continued to deteriorate since the floods in November 2019. We can therefore be certain that flooding is no longer an occasional phenomenon during these months. It is an everyday occurrence, ”said Tesserin, whose honorary chairman, First Procurator of St. Mark, dates from the ninth century.
In the last two decades there have been almost as many floods over 1.1 meters in Venice – the official value for “acqua alta” or “high water”, caused by tides, winds and lunar cycles – as in the past 100 years: 163 vs. 166, according to city data.
Exceptional floods over 140 centimeters (4 feet, 7 inches) are also accelerating. This mark has been hit 25 times since Venice began keeping such records in 1872. Two-thirds of these were recorded in the last 20 years, with five or a fifth of the total from November 12th through December. 23, 2019.
“What is happening now is on the continuum of the Venetians who have always lived with periodic floods,” said Jane Da Mosto, general manager of We Are Here Venice. “We live with floods that are becoming more common, so my concern is that people have not really realized that we are in a climate crisis. We are already living it. It’s not about plans to deal with it in the future. We have to have solutions ready for today. “
The defense of Venice has been entrusted to the Moses System of Moving Underwater Barriers, a total cost of around 6 billion euros (nearly $ 7 billion) that is still officially in the testing phase after decades of cost overruns, delays and a bribery scandal.
After the devastation of the 2019 floods, the government of Rome put the project under the control of the ministry to expedite its completion and started activating the barriers last year when floods of 1.3 meters (4 feet, 3rd Customs) are imminent.
The barriers have been raised 20 times since October 2020, saving the city a season of heavy flooding, but not the increased tides.
Extraordinary Commissioner Elisabetta Spitz stands for the soundness of underwater barriers, despite concerns from scientists and experts that their benefits could be exceeded within decades due to climate change. The project was again postponed until 2023 with an additional 500 million euros ($ 580 million) for “improvements” that Spitz said will ensure its long-term efficiency.
“We can say that the effective lifespan of the Moses is 100 years, taking into account the maintenance required and the interventions to be carried out,” said Spitz.
Paolo Vielmo, an engineer who provided expert opinions on the project, points out that sea level rise was projected to be 22 centimeters (8 1/2 in) when the Moses was first proposed more than 30 years ago, well below the UN scientists’ current worst-case scenario of 80 centimeters.
“That makes the Moses out of competition,” he said.
Under current plans, the Moses barriers will not be raised in the event of 1.1 meters (3 feet, 7 inches) flooding until the project is finally approved. That leaves St. Mark exposed.
Tesserin oversees the work to protect the basilica by installing a glass wall around its base, which will eventually protect the marshy lagoon water from ingress, where it deposits salt that eats away at marble columns, wall coverings and stone mosaics. The project, which is still being interrupted by floods, should be completed by Christmas. Now Tesserin says that they will be happy to have it ready by Easter.
Regular floods trigger a sober reaction among the Venetians, who are used to lugging rubber boots around with them every flood warning, and delight tourists who are fascinated by the sight of the golden mosaics and domes of St. Mark’s Square, which are reflected in the rising water. But companies along St. Mark’s Square are increasingly seeing themselves as ground zero of the climate crisis.
“We have to help this city. It was a light to the world, but now it takes the whole world to understand, ”said Annapaola Lavena, speaking from behind metal barriers that kept the water from reaching 1.05 meters (3 feet, 5 inches) to invade their marble-floored café.
“The Acqua Alta is getting worse and worse and is blocking business completely. Venice lives 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 it, but we suffer a lot.”
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Follow all of AP’s climate change stories at https://apnews.com/hub/climate-change.
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