NEW YORK  — Within the next three decades, floods that used to strike the New York City area only once every 500 years could occur every five years, according to a new scientific study released just days before the fifth anniversary of Superstorm Sandy.

The study, performed by researchers at several universities and published Monday in the Proceedings of the National Academy of Sciences, primarily blames the predicted change on sea-level rise caused by global warming.

“This is kind of a warning,” said Andra Garner, a Rutgers University scientist and study co-author. “How are we going to protect our coastal infrastructure?”