Scientists say a dramatic worldwide coral bleaching event is now underway

For just the third time on record, scientists say they are now watching the unfolding of a massive worldwide coral bleaching event, spanning the globe from Hawaii to the Indian Ocean. And they fear that thanks to warm sea temperatures, the ultimate result could be the loss of more than 12,000 square kilometers, or over 4,500 square miles, of coral this year — with particularly strong impacts in Hawaii and other U.S. tropical regions, and potentially continuing into 2016.

The event is being brought on by a combination of global warming, a very strong El Nino event, and the so-called warm “blob” in the Pacific Ocean, say the researchers, part of a consortium including the National Oceanic and Atmospheric Administration as well as XL Catlin Seaview Survey, The University of Queensland in Australia, and Reef Check.

“This is only the third time we’ve seen what we would refer to as a global bleaching event, an event that causes mass bleaching in the Indian Ocean, the Pacific Ocean, and the Atlantic-Caribbean basin,” said Mark Eakin, who heads NOAA’s Coral Reef Watch. The prior events, Eakin continues, “were in 1998 and 2010, and those were pretty much one year events. We’re looking at a similar spatial scale of bleaching across the globe, but spanning across at least 2 years. So that means a lot of these corals are being put under really prolonged stress, or are being hit 2 years in a row.”

The total loss could amount to 5 percent of the world’s corals in 2015, according to Eakin. That’s not as bad as the loss in 1998, but there’s a fear that if the event continues into 2016, the losses would grow.

“We’ve been hearing worrying reports of bleaching from various places, and now the bad news is officially here, with worse news likely yet to come with the strengthening El Nino,” says Nancy Knowlton, an expert on coral reefs with the Smithsonian Institution, of the news. “No reefs that experience unusually warm waters are likely to escape unscathed, but reefs already suffering from overfishing and pollution may have a particularly rough time recovering, based on what we have learned from past bleaching events.”

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