Hot oceans are killing corals worldwide
Record-high ocean temperatures have triggered a mass bleaching event in coral reefs around the world. It’s the fourth such event on record, and on track to be the worst. Over the past 14 months, bleaching has been documented in every major ocean basin, from the Florida coast to Australia’s Great Barrier Reef. In some places, the water has been so hot that the corals haven’t had time to bleach; they’ve simply died, as if cooked. Corals are stationary animals that get their bright colors from the symbiotic algae they depend on for nutrients. When they are stressed from overheating, they release that algae, turning the reefs white. Usually, such bleaching doesn’t mean the coral is dead, but it is a warning sign that it will perish unless conditions improve. Unfortunately, scientists think that’s not going to happen any time soon: Seasurface temperatures have been setting neardaily records for more than a year, driven by an El Niño weather pattern and climate change. “There’s nowhere to hide from global warming,” marine biologist Terry Hughes tells Scientific American. “Even the most remote and most pristine coral reefs are vulnerable to these repeated bouts of bleaching.” Loss of the world’s reefs would be a massive blow to the marine ecosystem. Reefs nurture a quarter of all marine species at some point in their life cycles and support fish that are eaten by millions of people.