Rising Seas: A View from New York City
"Rising oceans will eat away at the nearly 2400 km of shoreline encircling the greater New York City metropolitan region -- presently home to 19.6 million people... sea level rise could accelerate severalfold, as mountain and polar glaciers melt and upper ocean layers heat up and expand, due to global warming."

"How would rising sea levels affect the New York City area? ... A team of scientists from the Center for Climate Systems Research, Goddard Institute for Space Studies and Columbia University has investigated these issues as part of the Metropolitan East Coast (MEC) Assessment."

"[They] estimate future sea levels by extrapolating historical trends and using two global climate model (GCM) projections..."

"The two models suggest that ocean waters in this area could rise ... 18 cm [0.6 feet] to 60 cm [2 feet] by mid-century, as the planet warms. By the 2080s, sea level could climb by 24 cm [0.8 feet] to nearly 110 cm [3.6 feet], in some locations ...."

The risk to New York City does not come from rise in sea level by itself. The risk comes from the increased frequency and effect of flooding due to storm surge. Right now, storm surges that could inundate parts of the city that have an elevation of less than three meters (ten feet) may be expected on average once every one hundred years (a '100-year flood'). The parts of the city that would be affected by such a surge are shown in blue in the figure below.

But as sea level rises, in a worse case scenario, floods produced by surges associated with '100-year storms' could inundate areas with elevations up to almost fourteen feet (3.8 meters) by the 2080s: 10 feet due to the storm surge, plus 3.6 feet due to sea level rise. Looking at it another way, areas shown in blue (those with elevations less than ten feet above current sea level) on the figure above might be expected to be flooded much more frequently: as often as once every 50 years, given present rates of sea level rise, and as often as once every 4 years, in the worst-case scenario. The effects upon the city would be serious. "Flood waters would periodically cover significant portions of lower Manhattan, Coney Island, the Rockaways in nearby Queens, and entire neighborhoods on Staten Island. The metropolitan transportation system could be seriously disrupted because most area rail and tunnel entrance points, many transportation corridors, and portions of JFK, LaGuardia, and Newark Airports lie at elevations of 3 m or less."