Can Corals Survive In A Warming World? The world could lose all its coral reefs within the next century. As the Earth heats up, warming ocean waters could be deadly to these fragile ecosystems. On the Caribbean island of Bonaire, scientists are trying to figure out how to help coral reefs become more resilient.
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Can Corals Survive In A Warming World?

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Can Corals Survive In A Warming World?

Can Corals Survive In A Warming World?

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From NPR News, this is ALL THINGS CONSIDERED. I'm Madeleine Brand.


And I'm Melissa Block.

The world could lose all of its coral reefs within our children's lifetimes. As the Earth heats up, warming ocean waters could be deadly. The fate of coral reefs will depend in part on how healthy they are to begin with. For the second story in our series Oceans at Risk, NPR's Richard Harris travels to an island where scientists are trying to help coral reefs become more resilient.

RICHARD HARRIS: Coral reefs are the rainforests of the oceans, teeming with diverse and postcard-perfect fish, towering sponges, and multicolored coral. The magnificent ecosystem along the shores of the Caribbean island of Bonaire is also a vital human resource: think scuba tanks.

(Soundbite of hammering metal)

HARRIS: I think it's fair to say that's the sound of the economy of Bonaire, wouldn't you think?

Dr. RAMON DE LEON (Manager, Bonaire Marine Park): Exactly. Definitely. You will hear this noise all day long, all around Bonaire.

HARRIS: Ramon de Leon is in charge of Bonaire's National Marine Park. It's one of the healthiest coral reefs in Caribbean, and it's his job to keep it that way.

Dr. DE LEON: Bonaire is known as a diver's paradise. Anywhere between 50 and 70 percent of the economy is running tourism, and 90 percent of the tourism is diving tourism.

HARRIS: On this balmy evening, de Leon has come to this combination bar and dive shop to meet up with a team of scientists. They plan to spend the next 10 days in the water to see how the reef is doing.

Dr. GABRIEL GRIMSDITCH (Scientist, International Union for Conservation of Nature): Hi. Are you Henry(ph)?

HENRY: Yeah.

Dr. GRIMSDITCH: Hi, Gabriel. Nice to meet you.

HENRY: Nice to meet you, Mr. Gabriel.

HARRIS: Gabriel Grimsditch, from the conservation group IUCN, has organized the research. Their mission is to identify the factors that can keep this reef healthy and resilient. These scientists can't stop global warming from overheating the surrounding ocean waters, but they can identify other problems that make the coral more vulnerable to heat damage.

Dr. GRIMSDITCH: Okay, so where should we start? Maybe we can go through the methods.

HARRIS: Grimsditch explains that this is part of a project that's taking place around the globe. It was stimulated by a massive ocean warming episode 11 years ago. Overheated waters worldwide forced the colorful microorganisms that live inside the coral to abandon their homes. The coral turned white, it bleached. And a staggering 16 percent of all the world's coral died off during that episode.

Dr. GRIMSDITCH: And it basically got people thinking that climate change was actually one of the most important threats to corals at the moment. So people started looking at why coral reefs recover from bleaching or why they don't.

HARRIS: That's one reason they've come to Bonaire. The reef here was hit hard during the 1998 bleaching episode.

Marine biologist Mark Vermeij, from the nearby island of Curacao, remembers it vividly.

Dr. MARK VERMEIJ (Marine Biologist): The reef slope actually looked like a mountain slope full of snow. People here were taking their skis out and took pictures for home, like they were skiing the coral reefs.

HARRIS: But much to everybody's relief, the coral here didn't die off. The live-in microorganisms eventually returned to the mineral coral skeletons. The reef regained its color and came back to life. But Bonaire's reefs may not stay healthy enough to bounce back next time. Some parts of the reef are under pressure from the very people who come to admire them.

Unidentified Man: (Foreign language spoken)

HARRIS: The next day, the biologists take their first dive. It's right off one of the many resorts on Bonaire. Ramon de Leon squeezes into his wetsuit and straps on a 35-pound tank.

Dr. DE LEON: How do I look?

(Soundbite of laughter)

HARRIS: You look glorious.

Dr. DE LEON: No, that's the (unintelligible).

HARRIS: Clipboard in one hand, measuring square in the other, de Leon trudges across a small beach of imported sand and leads his colleagues into the water.

(Soundbite of splashes)

HARRIS: This resort looks idyllic: the sand, palm trees, a tiki hut bar. But as Mark Vermeij emerges from the dive an hour later, he says the reef offshore looks bad.

Dr. VERMEIJ: This is not something you get happy about, that's for sure.

HARRIS: Sure, he saw a lot of corals out there.

Dr. VERMEIJ: But instead of pointing up, they're pointing sideways right now.

HARRIS: It turns out this reef was whacked by a tropical storm last October. That in itself shouldn't be such a big deal. Reefs have been clobbered by storms for millions of years and recovered. But Vermeij says the added stress of living alongside human beings made it hard for this reef to bounce back.

For one thing, nutrient runoff from the resort's lush gardens have encouraged green algae to smother the coral in places.

Dr. VERMEIJ: And you can sort of see what happens, right? You hit them once and then everything else follows. That algal overgrowth, diseases, sure, but death by a thousand cuts. That's what this is, right here.

HARRIS: Study coordinator Gabriel Grimsditch says pinpointing the problems and then eliminating the causes could actually help corals to recover from bleaching and natural disturbances.

Dr. GRIMSDITCH: We're trying to give Ramon some data that he can point to just to tell people the reef is being affected in this way. And there are certain actions that you can take to improve the resilience of the reef.

HARRIS: Ramon de Leon can't keep the water cool. But as park manager, he does have some sway over the threats that make the coral more vulnerable to overheating. We clamber into one of the park's well worn pick-up trucks and drive along the narrow island roads. This is actually a desert island, as in arid, dry. But people want it to look like the classic Caribbean paradise, so they plant coconut palms and other vegetation. Then they water. And the water rushes through the porous soils, sweeping nutrients with it.

Dr. DE LEON: These nutrients will end up, sooner or later, in the reef.

HARRIS: Nobody wants to hurt the reef, de Leon says. On the other hand, nobody really wants to hear from the park manager that they need to change their ways.

Dr. DE LEON: Sometimes you have to point fingers and say: This is the problem. You are the cause. You have to solve it. Nobody likes that so we have to do it very careful. But all in all, I think people appreciate what we do for the coral reef here.

HARRIS: Since de Leon came to Bonaire 11 years ago from Uruguay, he's been telling people that if they care about the reef, they need to think differently about everything from coastal development and irrigation to fishing. And when he wants to show off just how healthy a reef can be, he takes people to one of the island's more remote and unpopulated dive spots. In fact, the science team heads to one of those pristine sites the next day, an island mockingbird calls down from a cactus as the divers gear up, and Grimsditch makes a few last-minute adjustments to the science plan.

Dr. GRIMSDITCH: I think it's (unintelligible). That's pretty good. But I noticed that it looks like the corals are taking a lot more time.

HARRIS: Once again, the divers disappear beneath the waves. But this time, when Mark Vermeij comes back, he looks happier.

So how healthy is this reef compared to the one you were diving at yesterday?

Dr. VERMEIJ: This? Waters of magnitude is better.

HARRIS: Vermeij says the reef here felt the impact of the same storm that caused so much damage down the coast last fall.

Dr. VERMEIJ: I mean, yeah, this place got hammered like hell, but it's grown back as hell, too.

HARRIS: Everything that should be working to help the reef recover is working here, he says.

Dr. VERMEIJ: Like corals that were fragmented, so the ones that were lying on the ground for awhile, they're growing back. Lots of parrotfish, everybody happy. But, yeah, it doesn't result in a postcard reef sort of thing. Resilience: the ability to come back after you got kicked very hard. This is the place where it…

(Soundbite of laughter)

Dr. VERMEIJ: …where it actually works like that.

HARRIS: The lesson here is clear. A reef that's healthy to begin with can rebound. So Vermeij says to help these rich and abundant ecosystems survive global warming, we need to reduce the stresses that are on them now.

Richard Harris, NPR News.

BLOCK: At the new, you can watch a slideshow of some of the amazing organisms that live underwater off the island of Bonaire.

BRAND: And tomorrow, we head to Monterey Bay, California, as we wrap up our series Oceans at Risk. The burning of fossil fuels doesn't just pollute the air we breathe. It also hurts the ocean and everything in it.

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