Extensive coral mortality occurred at Kiritimati (Christmas Island), Kiribati, illustrated by images from before record heat stress in July 2015 (left) and after record heat stress in July 2017 (right). Credit: Kieran Cox, Kristina Tietjen Coral reefs provide enormous value to people around the world. They support fisheries, power tourism industries, protect coastlines from storms, and even help scientists discover new medicines. Altogether, these benefits are estimated to be worth about $9.8