America's coastline will see sea levels rise in the next 30 years by as much as they did in the entire 20th century, with major Eastern cities hit regularly with costly floods even on sunny days, a government report warns. By 2050, seas lapping against the U.S. shore will be 10 to 12 inches (0.25 to 0.3 meters) higher, with parts of Louisiana and Texas projected to see waters a foot and a half (0.45 meters) higher, according to a 111-page report issued Tuesday by the National Oceanic and Atmospheric Administration and six other federal agencies.