Coral reef biologists are often asked the same question again and again: "When my kids grow up, will there still be coral reefs?"
"That's a question I ask myself," says Christopher Cornwall, a research fellow at Victoria University of Wellington in New Zealand. "The greatest fear is that all the coral will be gone at a certain point in time."
New research shows that, in a hotter climate, urgent action will be needed to prevent the vast majority of coral species from collapsing by the end of the century. Humans will have to limit emissions of heat-trapping gases, but that alone likely won't be enough. Reefs may also need a helping hand through efforts like restoration or coral breeding, which cultivates heat-resistant varieties.
Without that, the picture looks increasingly grim. Coral reefs are biodiversity hot spots, supporting around a quarter of all fish species. Millions of people around the world also rely on them for food, jobs and flood protection, since reefs help prevent storm surges from inundating coastlines.
The dramatic impacts come from a climate triple whammy: marine heat waves, ocean acidification and overall warming. The oceans have borne the brunt of climate change thus far, absorbing the vast majority of heat caused by human impacts.