Powerful Hurricane Erin has undergone a period of astonishingly rapid intensification — a phenomenon that has become far more common in recent years as the planet warms. It was a rare Category 5 for a time Saturday before becoming a Category 4,

Hurricane Erin exploded in strength to a Category 5 storm in Atlantic waters just north of the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.