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NOAA: Global Bleaching Event Threatens World's Coral Reefs

Alice Lawrence, a marine biologist, assesses the bleaching at Airport Reef in American Samoa in February 2015. (XL Catlin Seaview Survey)
Alice Lawrence, a marine biologist, assesses the bleaching at Airport Reef in American Samoa in February 2015. (XL Catlin Seaview Survey)

The National Oceanic and Atmospheric Administration (NOAA) announced on Thursday that the world’s coral reefs are in the middle of a dramatic bleaching event. That’s when stressful environmental conditions kill off huge swaths of coral, leaving it bone-white and unable to support marine life.

It’s only the third time in history that we’ve seen such an event, and it’s potentially disastrous for the world’s oceans. Mark Eakin, a marine ecologist and coordinator of NOAA’s Coral Reef Watch program, talks with Here & Now’s Jeremy Hobson about the coral bleaching, and says climate change is the culprit.

Interview Highlights

What is a coral bleaching event?

“First I’ll explain what coral is because most people don’t realize they’re a plant, an animal and a mineral all at the same time. And that’s important because inside the tissues of this animal are microscopic algae that provide most of their food. When the water temp gets too high the photosynthesis – the production of energy by these little plant cells – actually starts to run too fast and they start to release toxins into the coral. As a method of survival the coral will eject the algae into the water and it leaves their tissues translucent so you can see right through to the skeleton underneath, which is white. So it looks like it’s bleached, it looks like it’s dead, the tissues are actually still alive but you have a sick coral that’s starving and more susceptible to disease.”

Does El Niño contribute to this?

“That’s the interesting thing, just like how El Niño changes the climate around the world, it also influences patterns of circulation that can affect temperature of the water in other basins. So changes because of El Niño actually can cause temperatures to rise in the Indian and Caribbean Oceans.”

Can it be stopped?

“Once it’s gotten started, no. We’re talking about a huge amount of warm water, there’s just no capacity for cooling it. But the bigger question isn’t this event; the big question is the root cause and how we deal with it in the long term – climate change. We have been expecting it and unfortunately that’s what’s happening. The first global event was in 1998 related to a huge El Niño, the next one was in 2010, so the bad news is despite my having told you how bad things are now, the climate models make it look like this event is not only going to continue but may even be worse in 2016.”

Can the reefs be repaired?

“Reefs that were severely affected in 1998, they’re only partially recovering because some of the corals that died were over hundreds of years old and you can’t regrow a hundred-year-old coral in a decade or two. The real problem here is because of this increase in frequency and intensity of bleaching events relating to increasing CO2 in the atmosphere, we really have to address the root cause of climate change, and the climate treaty negotiations going on in Paris in December are critical to that.”

Why do these reefs matter?

“That’s always a question that comes up but there is the inherent value of having places like the Great Barrier Reef and other reefs around the world. These coral reefs are only one-tenth of 1 percent of the sea floor but they support over 25 percent of ocean fish species. These are areas that support about half a million people around the world who depend on the fish, they’re protecting shorelines. The services provided by coral reefs is tremendous to many parts of the world, so this is a very important system that we need to make sure is able to survive.”


  • C. Mark Eakin, Ph.D., a coral reef specialist and coordinator of NOAA’s Coral Reef Watch program.

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