50 inches (1.3 metres)

“The New York City Panel on Climate Change released a report today with a number of unsettling projections for the coming century…Combine that with sea levels that are expected to rise 11 to 21 inches by the ’50s, 18 to 39 inches by the ’80s, and 22 to 50 inches by 2100, and New York City will be at risk from frequent floods.

Queens will bear the brunt of it, followed by Brooklyn, Staten Island, the Bronx, and Manhattan.”
Curbed.com, 18 Feb 2015

see also – sea level

thanks to Igor Karlich