Sea-level rise poses expensive questions for New York City

John J. Fialka in E&E:  Mayor Michael Bloomberg has given his city one of the most detailed and highly publicized plans to reduce carbon emissions and to adapt to rising sea levels and other risks posed by climate change. He launched his program in 2007 and used it as a platform to vault into the chairmanship of C40, an international group of 40 big-city mayors determined to deal with the complex welter of climate issues they face. "Mayor Bloomberg is shaping the global dialogue and action on climate change in cities," boasts the latest version of New York City's plan, known as "PlaNYC."

....While Mitt Romney and other major Republicans sow doubts about climate issues and many Democrats -- including at times President Obama -- have soft-pedaled them, Bloomberg's plans appear to confront the difficulties of climate change head-on. "The scientific evidence is irrefutable," PlaNYC says. "Rising sea levels are extremely likely," says the New York City Panel on Climate Change, appointed to advise the city on carrying out the plan.

...But there is also a steep downside. Because New York City has more than 520 miles of coastline, it is among the top 10 port cities in the world that are most exposed to coastal flooding. Measured in terms of private property subject to damage from more potent storms and torrential rains that scientists predict are coming with climate change, the low-lying Big Apple ranks second in the world, with $2.3 trillion of property at risk, according to its own data.

One of the first victims of the flooding will likely be the same underground transit systems that make New York's carbon dioxide emissions so low. A recent report by the New York State Energy Research and Development Authority warned that the combination of sea-level rise and the surging ocean currents that can accompany a powerful storm could flood many of the city's subway, highway and rail tunnels "in less than one hour."...