A marine heat wave is warming the waters off the coast of Florida, pushing temperature readings as high as 101 Fahrenheit and endangering a critical part of sea life: the coral reef. Catrin Einhorn, who covers biodiversity, climate and the environment for The Times, discusses the urgent quest to save coral and what it might mean for the world if it disappears. Guest: Catrin Einhorn, a biodiversity, climate and environment correspondent for The New York Times.