If climate change continues unchecked, it could destroy the world’s great coral reefs within a century, according to a new report conducted by German and Australian marine scientists and released by Greenpeace. A rise in water temperature of just one or two degrees stresses coral and causes it to expel its life-giving microscopic zooxanthellae plants, a process called bleaching. It can take decades for reefs to recover from bleaching, and if bleaching happens too often, they may not be able to recover at all. In 1998, the warmest year on record, every reef system in tropical oceans experienced some degree of bleaching.