New York and the Surging Sea: A Vulnerability Assessment with Projections for Sea Level Rise and Coastal Flood Risk
Sea levels are rising at an accelerating rate, and the scientific community is confident that global warming is the most important cause. Higher sea levels translate to more and higher coastal floods. Using local sea level projections closely aligned with a likely midcentury range developed by the New York City Panel on Climate Change, this analysis finds a 3-in-4 chance of historically unprecedented coastal flooding in New York City by 2100, assuming sea level rises on the fast end of the spectrum; or a 1-in-10 chance under a slow rise scenario, as might be expected under reduced carbon emissions. We find that sea level rise from warming has already increased the likelihood of extreme flooding at the Battery – flooding high enough to seriously threaten the subway system – by 50%.
120 square miles of land lie less than 6 feet above the high tide line in New York, the height of a statistically extreme flood. This land is home to nearly half a million New Yorkers, 18% of whom live in just three zip codes. $97 billion in property value sits on the same land, as do more than 1,500 miles of road, 1,000 EPA-listed sites, and 100 schools. These numbers nearly double when assessed at 9 feet above the high tide line – Sandy’s peak flood elevation as measured at the Battery in New York City. In Manhattan and Brooklyn, the most socially vulnerable populations are about 50% more likely than the population as a whole to be flooded at this level.