For his published research, Oppenheimer looked at New York City's record flood of 1821. Sandy flooded even higher. This week's damage was augmented by the past century's sea level rise, which was higher than the world average because of unusual coastal geography and ocean currents. Oppenheimer walked from his Manhattan home to the river Monday evening to watch the storm.
"We sort of knew it could happen, but you know that's different from actually standing there and watching it happen," Oppenheimer said from a cell phone. "You don't really imagine what this looks like until you see it."
Associated Press writers Jennifer Peltz and Malcolm Ritter in New York and Michael Gormley in Albany contributed to this report.
Seth Borenstein can be followed at http://twitter.com/borenbears .