Venetian authorities consider any tide above 140 centimeters (4.5 feet) to be “exceptionally high,” and sirens sound around the city to let locals know it’s coming. In recent years exceptionally high tides have become more common, including four this month alone.
St. Mark’s Square, the most famous and vulnerable part of Venice, is also one of its lowest points, so an acqua alta of 140 centimeters above sea level would result in 60 centimeters of waters flooding the square, according to the city’s official tourism website. But half of the city would remain dry.
That’s not what happened this time.
What was so bad this time?
In what was the worst flood for Venice since 1966, the high water on Nov. 12 reached 184 centimeters, or 6 feet, above sea level.
A combination of rising tides and winds of more than 75 miles per hour from two different directions caused massive waves to crash into Venice.
St. Mark’s crypt and mosaic floor have been damaged, the baroque church of St. Moses and the city university, in a 15th-century Gothic palace, have been flooded. A man died from electrocution when the water caused a short circuit. The city’s mayor called it “a disaster,” and the local governor likened it to “a scene of devastation from the Apocalypse.”
“Those are the effects of climate change,” Mayor Luigi Brugnaro tweeted.
The climatic conditions certainly did not help. But neither did the steady digging of the canals to allow bigger vessels — particularly cruise ships — into the canals, allowing more water into the lagoon.
Andreina Zitelli, an expert on environmental assessment at the University of Venice, said that since the lagoon was modified for larger ships in the 1960s, the “more you dig, the more water you get.”