LIANE HANSEN, host:
The lagoon surrounding the 1,300-year-old island city of Venice is the site of an ambitious engineering project. It involves the construction of mobile floodgates aimed at safeguarding one of the world's most endangered cities. But some scientists say the project may not be enough to protect Venice from rising sea levels caused by climate change.
NPR's Sylvia Poggioli has this report.
(Soundbite of water splashing)
SYLVIA POGGIOLI: Venice rose from mudflats in the middle of a lagoon which forms the largest wetland in the Mediterranean. The island city has been subject to increasing flooding due to sinking land, but also to rising sea levels. It's known as aqua alta - high water - which brings city life to a standstill for several hours. Big boats can't go under low-hanging bridges and water seeps into buildings through the sewage system. Venetians have not lived on the ground floor for decades.
Sophisticated technology is now being used for what has become a full-scale emergency.
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POGGIOLI: At one of the three inlets that lead from the sea into the lagoon, a massive mechanical hammer is driving the steel and concrete piling into the lagoon bed. Elena Zambardi works for the consortium Safeguarding Venice. She says the use of pilings was invented by the visionaries who founded the city 1,300 years ago.
Ms. ELENA ZAMBARDI (Safeguarding Venice): (Through translator) In Venice, for example, under the Salute Church and the Rialto Bridge, there are piles, wooden piles to consolidate the subsoil.
POGGIOLI: The project acronym is MOSE, which is also the Italian word for Moses, recalling the biblical parting of the sea.
Once completed in 2014, there will be 78 large, mobile floodgates at the three inlets. When not in use, they'll lay below water on the lagoon bed. When a high tide is forecast, Zambardi says, the gates will rise and shut off the sea from the lagoon.
Ms. ZAMBARDI: (Through translator) And MOSE will defend Venice if the sea level rises up to 60 centimeters.
POGGIOLI: But the project, which is 54 percent completed, has been hounded by controversy and, critics say, may already be outdated.
The IPCC, the Intergovernmental Panel on Climate Change, has forecast a sea level rise by the end of this century of between 18 and 59 centimeters. But scientists caution it could be even higher.
Marine scientist Laura Carbognin has been studying the Venetian Lagoon for decades. Like many scientists, she fears the rising sea levels could mean the floodgates will be closed often and for long periods. That would upset the vital exchange between the sea and the lagoon, suffocating its delicate ecosystem. Carbognin co-authored a report that suggests another radical solution.
Dr. LAURA CARBOGNIN (Marine Scientist): To complement the Moses solution, it is necessary that all the city is uplifted.
POGGIOLI: She says research already suggests the feasibility of raising Venice.
Dr. CARBOGNIN: Based on hydrological and geochemical data, the preliminary simulation shows that fluid injection into deep formation can uniformly raise Venice up to 30 centimeters over 10 years.
POGGIOLI: Carbognin hypothesizes injections of salt water or even carbon dioxide at a depth of 600 to 800 meters below the lagoon, but she concedes much more research is needed. That would mean huge investments at a time when delays in state funding for the $6 billion plus Moses have already substantially delayed the project's completion.
Sylvia Poggioli, NPR News.
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