Coral Reefs Are Heading Toward the Worst Global Mass Bleaching on Record

According to U.S. government scientists, coral reefs are approaching a fourth global mass bleaching event caused by global heating. The occurrence is expected "to be the most extensive on record," 'The Guardian' reports. According to the National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Watch, about 54% of ocean waters that contain coral reefs have endured enough heat stress to cause bleaching.