35 percent, the researchers said, is an “initial estimate” from different reef regions. “There’s no other natural phenomenon that can cause that level of coral loss at that kind of scale,.” researchers said. Some dead corals were 50 or 100 years old. Statistical analysis suggested that by the year 2034, a March with sea temperatures as warm as occurred in 2016 could happen every other year, as the planet continues to warm. “Unfortunately, there are islands in the central equatorial Pacific Ocean like Christmas Island where the effects have been even more catastrophic, over 80 percent mortality,” said Mark Eakin, who coordinates the National Oceanic and Atmospheric Administration’s Coral Reef Watch.