New York, and every other city, was built with certain climactic baselines in mind. This much rain, this much snow, this much heat, this many floods. They form a core set of assumptions about the kind of infrastructure the city needs. Institutions grow up around that set of givens; they are a fixed point in the otherwise tumultuous process of urban governance. Maps are created showing the 100-year flood zones; they show the places that have a one-percent chance of being flooded in any given year.
2/3 of Sandy-Damaged Homes in N.Y. Were Outside the 100-Year Flood Zone
As the Wall Street Journal puts it: Sandy alters "reality."