Tiny, waterlogged Tangier Island, off the coast of Virginia in Chesapeake Bay, is full of people of faith. They believe in God. Climate science, not so much. In recent years, they’ve garnered some media attention for the paradox of largely rejecting sea-level rise while simultaneously suffering its wrath. Earl Swift, an author of six previous books and a former correspondent for The Virginian-Pilot, immersed himself for the better part of two years with the 481 inhabitants of Tangier. His new book, “Chesapeake Requiem: A Year with the Watermen of Vanishing Tangier Island,” is part regional history, part crabber ride-along, part disaster narrative in slow motion.