Warming bleaches Great Barrier Reef corals for second year in a row

The largest living structure on Earth—an intricate marine system half the size of France, which nurtures 1,500 species of fish—is under attack by warm water for the second time in 12 months. And the window to save it is closing rapidly. Australia’s Great Barrier Reef is suffering from another massive bleaching event, the first time in memory such episodes have hit in back to back calendar years. While last year’s bleaching was aided by a massive El Niño—a periodic natural warming period event in the tropical Pacific—2017’s damage is occurring with no such help. The reef is ailed not by a rare climatic phenomenon but by the baseline warming of the oceans.

“The data are truly daunting,” said Robert Richmond, director of the Kewalo Marine Laboratory at the Pacific Biosciences Research Center (PBRC). “These massive bleaching events have become more severe, are longer lasting and are coming closer together. There just is no question that this is tied to climate change.”

Until this decade, back-to-back bleaching events like that simply didn’t happen.“It’s new. It is so new. It’s a complete change in the phenomenon that all of us study,” said Ruth Gates, director at the Hawaii Institute of Marine Biology (HIMB) and the president of the International Society for Reef Studies. “We knew that this day would come—we’ve been seeing the thermal-tolerance threshold for corals get closer and closer, and we knew it was pushing over the limit for coral survival.”
 Read more about it in The Atlantic and National Geographic.