GURAIDHOO, Maldives — From the foyer of his small guesthouse some 100 feet from the shoreline, Mohamed Nizar, 52, was wondering how long his business could remain viable.

Last year, during an unusually nasty storm, water snaked through the narrow streets of Guraidhoo, a small island in the Maldives, pooling around the floor of the three-room house and chasing away guests.

Down along the beach, the picture was even worse. Erosion of the shore has become so severe, he said, that the owner of a neighboring guesthouse stakes plastic jerrycans in the sand to curb flooding during sea swells.

“What is the lagoon now used to be the football field on this island,” Mr. Nizar said on a recent afternoon. “I have to leave this guesthouse if it keeps eroding. I am sure of it.”