For people in the southeastern United States, and especially in Florida, who feel that annoying tidal flooding has sneaked up on them in recent years, it turns out to be true. And scientists have a new explanation.

In a paper published online Wednesday, University of Florida researchers calculated that from 2011 to 2015, the sea level along the American coastline south of Cape Hatteras rose six times faster than the long-term rate of global increase.

“I said, ‘That’s crazy!’” Andrea Dutton, one of the researchers, recalled saying when a colleague first showed her the figures. “ ‘You must have done something wrong!’ ”

But it was correct. During that period of rapid increase, many people in Miami Beach, Fort Lauderdale and other coastal communities started to notice unusual “sunny-day flooding,” a foot or two of salt water inundating their streets at high tide for no apparent reason.