One of the main reasons behind the charm of Venice, is the fact that is seems to be floating upon the waters of the lagoon. However the dark truth is that the city is actually sinking and has been for centuries. Venice has always lived on borrowed time, it is a city that should not exist – a whimsical maze of heavy marble palazzi and churches built upon ancient wooden piling sunk into a salt marsh. It is a wonder that Venice survived to the present day to face a threat that may finally end the life of this faded beauty: rising sea levels due to global climate change.
Sinking Venice: Acqua Alta
A major threat to the city of Venice are the extreme high tides known as “acqua alta“. The official definition of acqua alta is when the water level at high tide is over 90mm (3.54 inches) above normal. The most common occurrence of the acqua alta is in and around Piazza San Marco, where even a normal high tide can cause flooding in front of the Basilica San Marco. Severe acqua alta events have been known to cover nearly the entire city, with homes and businesses throughout Venice having to be evacuated.
Living at sea level is bound to bring in the sea from time to time and Venice was no exception throughout its long history. However these abnormal high tides are becoming more commonplace as Venice now experiences more than 60 days a year of extreme high tides. Acqua alta is the most serious threat to the survival of Venice, yet the main cause behind the acqua alta is a more global concern: rising sea levels.
There is growing evidence of world climate change and with the warming of the earth, comes the melting of the polar ice caps. Venice may not be the only location threatened by the rising oceans, but along the city’s tranquil canals the evidence for global warming can be seen by the abandoned ground floors of the famous palazzi. Former boat houses and even dwellings across Venice are now half-flooded with seawater due to rising sea levels. When the average sea level in the Venice lagoon rises, the city suffers. When you add in the increasing frequency of the acqua alta, Venice will drown.
The last bad flood was in November 12, 2019. The tide reached 187 cm, the highest since the historic flooding of 1966, when it went up to 194 cm. There were two casualties in Pellestrina, an island of the Laguna. The crypt in the Basilica of St. Mark was completely flooded. Shops and restaurants suffered severe damages. Three vaporetti sunk, many others went adrift.
The flooding in November 2019.
The previous bad high tide was in October 29, 2018, 75% of the town surface was covered in water, the worst in the last 10 years. Saint Mark’s Square was under 80 cm of water and was closed to public for security reasons.
High tide October 2018.
Sinking Venice: Earth Subsidence
The acqua alta is not the only threat facing La Serenissima, one of it’s oldest problems is still causing Venice to sink. For most of Venice’s history, earth subsidence was the greatest threat to the city. The very ground that Venice was built upon – low lying salt marsh islands – were dissolving. Even before the rising sea was considered a concern, the foundations of Venice were crumbling underneath her. Every century would see Venice sink a few more centimeters into the lagoon, however in the 20th Century this sinking was exacerbated by the effects of local industry.
During the 1950’s, mainland industries began extracting fresh water from nearby artesian wells, not understanding that much of this fresh water actually lay below the city of Venice. When this water began to be extracted on a large scale, Venice began to sink at an alarming rate, as if the heavy city of marble would eventually crumble into the now empty space below it. This practice has since been stopped and with it a very serious threat to Venice’s survival has been for the most part alleviated.
Sinking Venice: Boat traffic
Today, with the major industrial threats to Venice taken care of, earth subsidence of another kind is still a problem due to the heavy and often reckless boat traffic speeding through the canals. The wake caused by these motor boats, not to mention the large cruise ships in the lagoon, create small but powerful waves that lap the stones lining the canals. However underneath the stone and brick of Venice, the waves and salt caused by this boat traffic is eroding away the mortal holding the city in place, as well as the very earth Venice is built upon.
Sinking Venice: What is Being Done
The most popular as well as the most controversial solution to the sinking of Venice is a plan called the MOSE Project (Modulo Sperimentale Elettromeccanico). Also known as Project Moses, the idea to create adjustable barriers at the Venice Lagoon entrances has been planned since the 1980’s and the project is still under completition. These barriers are designed to rest on the sea floor until Venice is threatened by an acqua alta event. When needed, the barriers then spring into action by rising to form a dam across the three entrances to the Venice Lagoon, thereby keeping the high water away from the city.
The MOSE Project is not without controversy as both environmental and budgetary concerns have been raised and have delayed the final completion of the project. Today the project has a budget of about 5 billion euros and is rotting even before it is finished. Environmental groups have voiced their concern about the overall health of the Venice lagoon in the wake of having the tidal ecosystem closed off from the sea for long periods of time. Venice relies on the tides to flush out its canals, severe acqua alta events could seriously damage the health of the local marshlands – essential as a fish hatchery as well home for the game and waterfowl that are traditional parts of the Venetian diet. Furthermore, in 2014 the project was caught in a scandal of corruption and bribes, that brought to the arrest of 35 people and 100 politicians and functionaries investigated.
Besides the MOSE Project, canal restoration, installation of more modern sewage systems and enforcement of boat traffic laws are all in their own way helping Venice to survive into the modern era. However the threats to her survival are still there and others, like increased rainfall from global climate change are rearing their ugly heads. However this is nothing new for Venice, the city and its people have always lived on borrowed time better than anybody else.
By Justin Demetri