Coral Bleaching Has Ravaged Half of Hawaii's Reefs

Photo: AP

Last week, scientists reported that half of Hawaii’s coral reefs suffered serious bleaching in 2014 and 2015 as part of an ongoing, three-year global bleaching event that researchers are still trying to get a handle on. Hawaii is home to some of the most spectacular reefs in the U.S., which bring in around $800 million a year in revenue.

Around 56 percent of the Big Island’s corals bleached, along with 44 percent on West Maui and 32 percent of the reefs around Oahu according to an Associated Press report.


“This report seems to be consistent with what we saw in our satellite data,” Mark Eakin, the director of Coral Reef Watch, told Earther. “I’m even more eager to hear about the mortality seen in the field.”

Getting a handle on what corals bit the dust is essential to scientists for two main reasons. In the near-term, it will help them understand the prospects of recovery for the reefs. Longer term, it will give them insights into what corals can survive marine heat waves.

Coral and algae have a symbiotic relationship. When water temperatures spike like they did in 2014 and 2015 as part of a strong El Niño, they essentially cook the algae out of the coral. Months of nonstop heat turn vibrant reefs into ghostly white graveyards. Climate change will make these heat waves more common in Hawaii and around the world.

“In the 2030s, 30 to 50 percent of the years will have major bleaching events in Hawaii,” Kuulei Rogers, a scientist at the Hawaii Institute of Marine Biology, told the AP.


Research has shown that if the planet warms more than 1.5°C (2.7°F), reefs will likely suffer irredeemably unless we figure out ways to help them cope. Scientists have been fiercely searching for corals that appear resilient to warm water because they could hold the key to ensuring reefs don’t go extinct.

The waters are currently running about 3°F above normal in Hawaii. That’s hot enough for a coral reef watch to be in place, but it’s not quite cook-algae warm. Forecasts for the region indicate waters should stay in that range, giving coral a bit of time to recover or at least not deteriorate further. A burgeoning La Niña will also help reduce heat in many other parts of the world, providing a further reprieve from the global bleaching event that officially ended in June 2017.


But not all locations are out of the woods. La Niña tends to cool the planet as a whole, but certain areas actually see temperatures increase, including the western Pacific. Reefs in the Coral Triangle—an area around Indonesia, the Philippines and Papua New Guinea—are dotted with bleaching warnings. The highest alert levels are also in place around Guam and other islands in the northwestern Pacific.

“There’s been very little news coverage of the fact that this is the fourth of the last five years that Guam has suffered widespread, severe bleaching and this year is the worst ever,” Eakin said.


Climate change is hardly the only threat to reefs. Overfishing, suntan lotion, sewage, and even aquariums are just a handful of other ways reefs are being stressed out by humans. But because reefs are so stunning, there’s also a lot of work being done to save them. Let’s just hope we get our act together before it’s too late.

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