Consolidated Edison, the utility that supplies electricity to most of the city, estimates that adaptations like installing submersible switches and moving high-voltage transformers above ground level would cost at least $250 million. Lacking the means, it is making gradual adjustments, with about $24 million spent in flood zones since 2007.
The most vulnerable systems, like the subway tunnels under the Harlem and East Rivers, would have been unusable for nearly a month, or longer, at an economic loss of about $55 billion, said Dr. Jacob.
Instead of “planning to be flooded,” as he put it, city, state and federal agencies should be investing in protection like sea gates that could close during a storm and block a surge from Long Island Sound and the Atlantic Ocean into the East River and New York Harbor.
The waters on the city’s doorstep have been rising roughly an inch a decade over the last century as oceans have warmed and expanded. But according to scientists advising the city, that rate is accelerating, because of environmental factors, and levels could rise two feet higher than today’s by midcentury. More frequent flooding is expected to become an uncomfortable reality.
With higher seas, a common storm could prove as damaging as the rare big storm or hurricane is today, scientists say. Were sea levels to rise four feet by the 2080s, for example, 34 percent of the city’s streets could lie in the flood-risk zone, compared with just 11 percent now, a 2011 study commissioned by the state said.
“There’s a lot of concern about angering developers,” said Ben Chou, a water-policy analyst at the Natural Resources Defense Council.