A grim situation is affecting coastal Nigeria, with the ocean gradually consuming a place once known as the nation's "Happy City." What's happening? The Guardian spotlighted Ayetoro, Nigeria, which has come to represent the kind of damage coastal erosion and rising seas can inflict on a whole community. "More than half of Ayetoro — a Christian utopia founded in the 1940s — has been lost to the ocean, and its remaining people are running out of o…