The warnings came, again and again.

For nearly a decade, scientists have told city and state officials that New York faces certain peril: rising sea levels, more frequent flooding and extreme weather patterns. The alarm bells grew louder after Tropical Storm Irene last year, when the city shut down its subway system and water rushed into the Rockaways and Lower Manhattan.

On Tuesday, as New Yorkers woke up to submerged neighborhoods and water-soaked electrical equipment, officials took their first tentative steps toward considering major infrastructure changes that could protect the city’s fragile shores and eight million residents from repeated disastrous damage.

Gov. Andrew M. Cuomo said the state should consider a levee system or storm surge barriers and face up to the inadequacy of the existing protections.

“The construction of this city did not anticipate these kinds of situations. We are only a few feet above sea level,” Mr. Cuomo said during a radio interview. “As soon as you breach the sides of Manhattan, you now have a whole infrastructure under the city that fills — the subway system, the foundations for buildings,” and the World Trade Center site.