The sinking city: Venice's $3 billion plan to stop a rising sea gets mixed reviews - Currents

E: The Environmental Magazine, March-April, 2003 by Colin Woodard

Using new carbon dating techniques, his team was able to calculate the rate of relative sea-level rise in the city going back 1,600 years. The data, Ammerman says, shows that the Consortium's plan seriously underestimates the likely rate of sea-level rise during the coming century. By adding Venice's long-term subsidence rate with the best available estimates of future sea-level rise, Ammerman reckons the sea will gain between 12 and 39 inches relative to Venice's streets.

If true the sea still wouldn't be nearly high enough to breach the massive gates when they're closed. The problem, Ammerman says, is that the gates will have to be dosed far more often than their planners say they will. Since virtually all of historic Venice's sewers empty straight into the city's canals and lagoon with little or no treatment, frequent lagoon closures could have serious environmental consequences.

"In a bad year [in the mid-21st century] you could have the gates closed for 100 or 120 days a year, with two-thirds of them in the three-month flood season," Ammerman says. He predicts the resulting pollution crisis would shorten the project's lifespan to 30 or 40 years. The Consortium, he insists, should go back to the drawing board and revamp its designs.

Consortium spokesperson Monica Ambrosini disagrees. "The problem of sea-level rise is very real, and the designs take it into account," she says. The company expects to start construction this year. CONTACT: World Wide Fund for Nature Climate Change Program, (202)293-4800, www.panda.org.