Flooding in Venice worsens out of season due to climate change

VENICE, Italy (AP) – After Venice suffered the second worst flooding in its history in November 2019, it was inundated by four more exceptional tides in six weeks, shocking Venetians and sparking fears of the worsening of the tides. impact of climate change.

The repeated invasion of brackish lagoon waters into St. Mark’s Basilica this summer is a quiet reminder that the threat has not abated.

“I can only say that in August, a month when this never happened, we had tides of over three feet five times. I’m talking about the month of August, when we’re calm, ”Saint-Marc chief guard Carlo Alberto Tesserin told The Associated Press.

Venice’s unique topography, built on piles of logs among the canals, has made it particularly vulnerable to climate change. Rising sea levels increase the frequency of high tides which flood the 1,600-year-old Italian lagoon town, which is also gradually sinking.

It is the fate of coastal cities like Venice that will preoccupy climatologists and world leaders meeting in Glasgow, Scotland at a United Nations climate conference that begins on October 31.

According to a new study released by the European Geoscience Union, the worst-case scenario for sea level rise in Venice by the turn of the century is 120 centimeters (3 feet, 11 inches). This is 50% higher than the global average of 80 centimeters (2 feet, 7 1/2 inches) predicted by the UN scientific panel.

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, a designation endangered late due to the impact of over-tourism and cruise ships. circulation. He escaped the endangered species list after Italy banned cruise ships from crossing the St. Mark’s Basin, but the alarm bells are still ringing.

Located at the lowest point of Venice, St. Mark’s Basilica offers a unique position to monitor the impact of the rising seas on the city. The outer plaza floods at 80 centimeters (about 30 inches) and water flows from the narthex into the church at 88 centimeters (34.5 inches), which has been reinforced from the previous 65 centimeters (25.5 inches).

“Conditions continue to deteriorate since the floods of November 2019. So we are confident that these months, the floods are no longer an occasional phenomenon. It’s an everyday fact, ”said Tesserin, whose honorary title, First Prosecutor of Saint Mark, dates back to the 9th century.

Over the past two decades, there have been almost as many floods in Venice over 1.1 meters – the official level for “acqua alta” or “high water”, caused by tides, winds and cycles. lunar – than in the previous 100 years: 163 versus 166, according to city data.

Exceptional floods of over 140 centimeters (4 feet, 7 inches) are also accelerating. This mark has been reached 25 times since Venice began keeping such registers in 1872. Two-thirds of these have been registered in the past 20 years, with five, or one-fifth of the total, from November 12 to December 12. 23, 2019.

“What is happening now is on the continuum for the Venetians, who have always lived with periodic flooding,” said Jane Da Mosto, executive director of We Are Here Venice. “We are living with flooding which has become more and more frequent, so my concern is that people have not really realized that we are in a climate crisis. We are already living it now. These are not plans to deal with it in the future. We must have solutions ready for today.

The defense of Venice was entrusted to the Moses system of movable underwater barriers, a project costing around 6 billion euros (nearly 7 billion dollars) and which, after decades of cost overruns, delays and a corruption scandal, is still officially in the test.

After the ravages of the 2019 floods, the government in Rome brought the project under ministry control to speed up its completion, and last year began activating the barriers when flooding 1.3 meters (4 feet, 3 meters) inches) are imminent.

Barriers have been lifted 20 times since October 2020, sparing the city a season of severe flooding but not low tides which are becoming more and more frequent.

Extraordinary Commissioner Elisabetta Spitz supports the strength of underwater barriers, despite concerns from scientists and experts that their usefulness could be exceeded within decades due to climate change. The project was further delayed, until 2023, with an additional 500 million euros ($ 580 million) in spending, for “improvements” that Spitz said will ensure its long-term effectiveness.

“The effective lifespan of the Moses can be said to be 100 years, taking into account the maintenance required and the interventions that will be carried out,” said Spitz.

Paolo Vielmo, an engineer who wrote expert reports on the project, points out that the sea level rise was predicted to be 22 centimeters (8 1/2 inches) when the Moses was first proposed he over 30 years ago, well below UN scientists. current pessimistic scenario of 80 centimeters.

“It puts Moses out of action,” he said.

Under current plans, the Moses barriers will not be raised for 1.1 meter (3 feet, 7 inches) flooding until the project receives final approval. This leaves Saint-Marc exposed.

Tesserin supervises the works of protection of the basilica by installing a glass wall around its base, which will ultimately protect the water of the marshy lagoon from infiltration inside, where it deposits salt which eats away at the columns of marble, wall coverings and stone mosaics. The project, which continues to be interrupted by high tides, was due to be completed by Christmas. Now Tesserin says they’ll be lucky to have it finished by Easter.

The regular high tides elicit a jaded reaction from the Venetians, accustomed to lugging rubber boots with every flood warning, and delight tourists, mesmerized by the sight of the golden mosaics of St. Mark and the domes reflected in the rising waters. But businesses along St. Mark’s Square increasingly see themselves at the zero point of the climate crisis.

“We have to help this city. It was a light for the world, but now the whole world has to understand it, ”said Annapaola Lavena, speaking behind metal barriers that kept the waters from reaching 1.05 meters (3 feet, 5 inches). ) to invade his marble-floored cafe.

“The acqua alta is getting worse and completely blocking business. Venice lives on its craftsmen and tourism. If there is no more tourism, Venice dies, “she explained.” We have a great responsibility in trying to save it, but we are suffering 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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