Could New York City have foreseen and protected itself from Superstorm Sandy's tidal surge? The question has been asked many times. Some, including my colleagues and I, believe natural barriers in the form of artificial reefs, sturdy dunes and barrier islands can help do the job. But while these can reduce the damaging effects of waves—the cold temperatures during Sandy kept the winds at a high altitude, thus producing fewer waves—if we are to protect against the storm surge itself, a broader system of specific and engineered protection is required.