The world is clobbering coral reefs, home to 25 percent of all marine species. Agricultural runoff pollutes the water around them; coastal developments tear them up; overfishing kills their inhabitants; and carbon dioxide emissions make the oceans too hot and acidic. In a provocative op-ed for the New York Times last year, Roger Bradbury, an ecologist at Australian National University, declared that reefs are "zombie ecosystems . . . on a trajectory to collapse within a human generation." The slightly more hopeful consensus statement from last summer's International Coral Reef Symposium (ICRS), attended by 2,000 scientists, noted that while 25 to 30 percent of the world's reefs were already "severely degraded," they could still be saved through "global action to reduce the emissions of carbon dioxide and other greenhouse gases, and via improved local protection."