MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Many of the 8,000 miles of coral reefs in the Caribbean are devastated. They've already declined by more than 50 percent since the 1970s. Joining me to talk about the health of the world's coral reefs and how to help them survive, Mark Eakin of the National Oceanic and Atmospheric Administration, Nancy Knowlton of the Smithsonian National Museum of Natural History. Joining us by phone from Winter Harbor, Maine, Andrew Revkin of The New York Times.

MS. DIANE REHMAnd throughout the hour, please join us. Call us on 800-433-8850. Send us an email to drshow@wamu.org. Follow us on Facebook or send us a tweet. And thank you all for being with us.

MS. NANCY KNOWLTONThanks for having us.

MR. ANDREW REVKINGreat to be with you.

MR. MARK EAKINGlad to be here.

REHMAnd to you, Nancy Knowlton. I know there's a major new report on the coral reefs in the Caribbean. Tell us about it.

KNOWLTONWell, for a long time we've known that reefs -- many reefs in the Caribbean were in trouble. And as part of the global coral reef monitoring network, it was decided to do an overall review, really collect a lot of data. And that's -- the report took about three years to compile. It's about 90 different locations for which data were available, 34 countries. So it's the biggest ever analysis of the state of Caribbean reefs that's been presented.

REHMAnd major findings?

KNOWLTONAnd the major findings are that, yes, coral on average has declined. But there are some places where coral is basically holding steady or even increasing. And the biggest causes of this decline since the 1970s has been overfishing and coastal pollution. And that's important, because those are things we actually know how to do something about.

REHMNow, that's really interesting because up to now hasn't there been a lot more blame placed on environmental change or climate warming?

KNOWLTONWell, I actually think that there's been quite a widespread recognition that overfishing and pollution do a lot of damage. But particularly with the increase in bleaching, the 1998 global bleaching event -- this happens when the water gets too warm, the corals lose their partners that photosynthesize and feed them and in many cases the corals die. So beginning in 1998 and in the Caribbean in particular in 2005 and 2010, we had really huge bleaching events. And I think the expectation was that those events would have had a broad impact across the Caribbean. And I think the message of the report is that, yes, there are places where you can effects of climate change.

KNOWLTONAnd of course, I think any coral-reef biologist is worried about future climate change, because the report says -- doesn't in any way argue that the future climate change is in a huge such race. But I think what it reinforces is that it still remains the case that up until now the biggest killers of coral has actually not been climate change, but has been as I said overfishing and pollution.

REHMAnd one of the fish that's been overfished is the parrotfish.

KNOWLTONYes, the parrotfish weren't necessarily high on the list of people's food preferences back in the seventies. But as overfishing generally has taken place, they've become more and more a part of the fishing activities. And they're incredibly important because they act like lawnmowers eating seaweeds. And seaweeds are the biggest competitor of corals. And so if you get rid of the lawnmowers, then the seaweed grows up and it smothers the coral or actually sometimes can make it sick from disease as well.

REHMSo explain in detail how this parrotfish has been so important to the coral. And now, with the overfishing, what's happening to the coral?

KNOWLTONSo parrotfish are herbivores. They eat seaweeds. And they're one of the most -- in the Caribbean, they're the most important seaweed eaters. And seaweeds compete with corals. They both are competing for real estate on the reef. Real estate is in short demand. And the problem with seaweeds is they grow much, much faster than coral. So if there isn't something that are munching on them all the time, eventually the coral gets covered by seaweeds and essentially smothered.

REHMAndrew Revkin, turning to you. Give us a sense of some of the history of these coral reefs. How did we get to where we are now?

REVKINWell, the deep history, of course, is that corals, as a group of animals with this symbiotic relationship with kind of plankton have been around for -- well Nancy or Mark can tell you how many hundreds of millions of years -- but it's a long, long time. And they've been through epic disruptions. You know, the earth's systems have been jolted by extinction spasms through the past that have been extraordinary. But corals have hung in there. One thing that I think it's important to recognize is that the coral -- usually when we, human beings in the 21st century, talk about the value of corals, we're talking about the reefs, just as Nancy was saying.

REVKINI mean, you know, nature doesn't really care if it's a weedy reef or a coral reef. And John Bruno, another really good marine biologist I've talked to a long time about this, says that essentially they're as productive, you know, in terms of just what's called primary productivity.

REHMHmm.

REVKINThere's no qualitative difference in the biological activity on a weedy, algae reef or a coral reef. But we kind of -- we love -- Fabien can tell you. I mean, I grew up watching his grandfather, you know, say ooh la la about this underwater world.

REVKINAnd that's what got me interested in being a, first, submarine biologist. I never ended up doing that. I became a journalist. And in the 1970s, I spent some time in French Polynesia. I was just mind boggled by the psychedelic -- at every scale. I mean, you could look at one inch or at a foot or at 100 feet or 100 yards of a coral reef and just be mesmerized by the activity. So it's the special nature of reefs, including their economic value, you know, as a source of tourist revenue in places like the Great Barrier Reef or sustainable -- just basic fishing for poor communities. That's the thing that we cherish.

REVKINAnd corals are not going away. There's nothing we could do, I think, in our short span of time on this planet to extinguish these -- this group of animals. It's the reefs that we have to be concerned about. And this gets back to one of the really important points in this IUCN analysis, which is there's a ton of stuff we can do right now to help improve prospects and even restore reefs in areas that -- in places like the Caribbean, where there's been so much pressure.

REHMSuch as?

REVKINThere's lots to do.

REHMSuch as?

REVKINOh, well, such as having -- establishing no-fishing zones. You know, areas where you could -- that serve -- it seems as sort of a -- if you leave some areas un-fished they can sort of potentially replenish and sort of give you enough activity that fishing communities can still have income, but that you're sort of sustaining the reefs as well. You'll hear more, I'm sure, in a few minutes about fishing techniques and which fish you choose and which fish you conserve.

REVKINThere are some things though that -- one thing that hasn't been mentioned yet, and this gets to the history of these reefs, is in the Caribbean, one of the biggest insults was something no one really sort of realized was happening until it had already happened. I'm sure Nancy or Mark could get you more on this, was this -- sometime in the, I think it was the early eighties, someone will answer that question...

KNOWLTONYes.

REVKIN...some new critter came into the Caribbean and devastated sea urchins, which are kind of like parrotfish. They go around grazing on algae. And that created an unbelievable diminishment of reef health that was -- that's actually been sort of not noticed. There was -- there's the -- we have what some scientists, including Jeremy Jackson, Nancy's husband, have talked about what's called shifting baselines of perception. People started worrying about global warming in recent years, but they didn't realize that the Caribbean already was kind of devastated by a hammer blow of this organism that probably came through the Panama Canal in ballast water on a ship.

REVKINAnd it has just wreaked havoc with sea urchins. So there are some things like that that, you know, you can't just magically...

REHMSure.

REVKIN...seed new sea urchins. But I'm sure you'll hear more.

REHMAndrew Revkin writes the Dot Earth blog for The New York Times. He's also senior fellow for Environmental Understanding at Pace University. Nancy Knowlton is the sant chair for Marine Science at the Smithsonian National Museum of Natural History. Mark Eakin, what did you think of the findings of this report?

EAKINWell, Nancy and I are really in agreement on most of the things that have gone on that we've been discussing in this report. The impact of the parrotfish was huge in starting things off. The one thing that's a difference between where I think the analysis could have gone if it had been dealt with a little differently and where it went, was in that analysis of the impact that climate change has had, the amount of coral bleaching that has gone on and the mortality in many of the corals.

EAKINEspecially in the period from 2005 onward, when there was a major bleaching event in the Caribbean and then again in 2010 when there was another major bleaching event in the Caribbean that just would have been right at the end of the period when these -- the data for this particular analysis cut off in 2012.

REHMAll right. And we're going to take a short break here. When we come back, Mark Eakin, I want to hear more about what it is that happens in the bleaching process -- what it is that happens to the coral and why. Short break. We'll be right back.

REHMAnd welcome back. Here in the studio, Nancy Knowlton of the Smithsonian National Museum of Natural History and Mark Eakin. He's coordinator of the Coral Reef Watch Program at the National Oceanic and Atmospheric Administration. On the line with us is Andrew Revkin. He writes the Dot Earth blog for the New York Times. Just before the break, Mark Eakin, you were talking about coral bleaching. Explain to our listeners what happens to coral when the bleaching process begins and why.

EAKINSo corals are fascinating organisms and they're actually fairly simply understood if you think back to the children's game 20 questions. Where do you start, animal, vegetable or mineral? And for corals it's all three. You have an animal. And living in the tissues of that animal are microscopic algae that are symbiosis living in a mutualistic relationship with the animal. They're both giving each other things in return for the services the other does. And through the way that that partnership works it allows the coral to deposit a hard skeleton of limestone. And that's the mineral portion.

EAKINSo the one thing that Andrew was saying earlier in terms of the productivity of an algae reef or a coral reef is very similar. They are but this bit about the secretion of a limestone skeleton is the one thing that makes those different because the corals are building a structure. It's like the difference between grass and trees. You built a habitat when you have trees.

EAKINBleaching happens when that relationship between the coral and the algae breaks down. And it happens because of stress. There are a number of stresses that can do it but the only one that causes this to happen over very large spatial scales and to the extent that we've been seeing is thermal stress, when the water gets too warm and stays too warm for too long. This causes -- it's interesting that it actually causes the algae to become too productive. And they start being so productive that they can't repair the little engines that they have for photosynthesis.

EAKINAnd as that goes on they start to release compounds that are toxic to the coral. The corals will actually eject the algae. They lose cells in the process. It's literally a gut-wrenching experience when they spit these out. And it leaves the coral in a disturbed state in a less healthy state. And it leaves them without the algae that give them their food.

REHMNow to what extent is the proximity of man in any way responsible for what happens in that kind of situation?

EAKINWell, there are two things. There's what happens initially and whether or not you're going to see much bleaching and how severe it is. And then there's a recovery phase after an event. So it turns out that actually one of the things that can lead to a more susceptibility of corals to bleaching is nutrients. So as we have more activity and more nutrients going in the water, the corals may bleach more easily.

EAKINWell, after a coral is bleached and even more so if corals have died and the reef is trying to recover, having a lot of pollution, having the parrot fish overfished, as we've been talking about, having the nutrients in the water having a lot of disturbance -- physical disturbance, habitat destruction, these all make the reefs less resilient to that thermal stress and to these events. And so it makes it harder for the reefs to bounce back and recover.

REHMSo how much coral bleaching has been going on more recently?

EAKINYou know, coral bleaching on these large scales really started in the early 1980s. And it was in '83 in the eastern Pacific and Caribbean that we first saw it. We've had these events going and they've been increasing in the severity overtime. We've now had six of these major bleaching events in the Caribbean since the 1980s and so -- coming back, like, every five years. The 2005 event though was really huge in terms of the impact that it had. A lot of reefs from the Bahamas down through the Lesser Antilles severely bleached, the Virginia Islands National Park. So this is, you know, one of your national parks, Diane.

EAKINAnd you probably didn't even hear that 90 percent of its corals bleached and over 60 percent of them died. Now just imagine that 60 percent of the Redwoods had died in one year. You would've heard about it. We had another big event in 2010 that actually was global and it had some effect in parts of the Caribbean, not the same areas but actually farther south in the Caribbean.

EAKINSo these have been big events and they've been going on and having major impacts. They tend to hit certain portions of the Caribbean. You know, different regions will be hit because of the atmospheric patterns that cause the warming that we see.

REHMAll right. And joining us now from California to talk about his recent 31-day underwater mission, oceanographic explorer, conservationist and documentary filmmaker, Fabien Cousteau. And Fabien, thank you so much for joining us.

MR. FABIEN COUSTEAUIt's a pleasure being amongst such distinguished people, Diane. And it's a pleasure being on your show.

REHMThank you. Tell us about Mission 31, which I gather you've just completed.

COUSTEAUI'm just getting dry now. Mission 31 was a project that recently concluded where I took a number of scientists from FIU, Northeastern and MIT to live underwater for 31 days and work out of the world's only undersea marine laboratory called the Aquarius which is located right off the Florida Keys at the bottom of the sea 63' down.

REHMTell me about that vessel, the Aquarius.

COUSTEAUWell, the Aquarius is the only remaining undersea marine laboratory in the world. My grandfather was one of the first to build undersea marine laboratories to experiment not only with human physiology as it pertains to living underwater, but also to be able to explore our oceanic world in an unprecedented way with the advent of the luxury of time that an underwater habitat affords us.

COUSTEAUIt is a magical place. It happens to be located in one of the most protected regions of the Florida Keys. And it allows us a foray into a coral reef that obviously is quite stressed for several reasons, but is protected to some extent which does allow us to get kind of an idea of what it's like when a coral reef is protected, and how it can fight off some of the other problems, manmade problems that are generated, such as climate change, pollution and such.

REHMNow tell me, from your vantage point, what you believe the particular advantage of studying the coral in this way is? What further information can you glean from being underwater 31 days to study the coral?

COUSTEAUWell, as far as our mission was concerned, our scientists said it best which is that they were able to do over three years of data collection in 31 days. It does give us an open door quite literally to our -- to that aquatic backyard where we can go diving 10, 12 hours a day which is just simply impractical if not impossible from the surface. It does allow us to keep a pulse on the health of coral reefs on a long term basis to be able to live and monitor in a place that has been studied for the last 20, 30 years just so we can see where the trajectory is going.

COUSTEAUAt the end of the day it also gives us more of a view and a better in depth view of things that we just simply can't study without being on the ground, or in the water in this case, on a constant basis. We have a lot of tools at our disposal, RVs, AUVs, submarines and such but at the end of the day being a human being connected with that aquatic environment in real time is -- gives us a unique view and perspective that just can't be had any other way.

COUSTEAUWe were able to use tools that normally are used in laboratories. Because of the controlled environment we were able to use them actually in the wild environment because we were there.

REHMNow, I'm wondering, Andrew Revkin, have you ever been on this particular vessel and what can you say about the experience?

REVKINI have not. I think I would...

REHMHe hasn't invited you yet, is that it?

REVKINNo. I think he did invite me actually.

COUSTEAUAndy's always invited but he's so busy. We need to get him down there.

REVKINWell, my challenge is I cover the terrestrial part of the world too and everything else in between so it's challenging. But what's great -- actually what Fabien didn't mention is the other great value of what he's done down there, including his use of social media and video and his help to convey the story, as you heard from others earlier that, you know, as Mark said, you know, you could have a big problem with a coral reef and within one of our national park waters and it not be a visible crisis.

REVKINWe're surrounded by environmental issues that I describe as slow-drip problems, the kinds of things that eat away at our patrimony in ways that you don't see on a day-to-day basis. And even with the bleaching episodes, you know, the IUCN report showed that, you know, the long term trend doesn't show yet their -- an impact from these events on the overall sort of coral status in the Caribbean. And yet we know, as you've heard earlier, that the trajectory is toward great diminishment.

REVKINAnd there's the acidification problem also that comes with global warming, CO2, carbon dioxide, the main greenhouse gas. When it goes into ocean water becomes -- it makes the water less -- it lowers the pH of the water. It heads away from being alkaline toward being acidic. And that can have a big impact on not just coral reefs but various kinds of plankton. And talk about the invisible things that we're doing, that shift in the chemistry of the oceans is completely invisible but very consequential in the long run.

REHMAnd Fabien, are you seeing the results of that shift in the chemicals of the ocean?

COUSTEAUOh, in the way that the reef is changing over just my short lifetime I've seen a huge, huge change. I think we all have. And Andy's absolutely right. One of our focuses is really for Mission 31 to be a communal platform -- communications platform for the world to really peer in in a way that maybe they hadn't been invited to do before. A lot of the things that we're talking about are invisible to the vast majority of human beings on this planet.

COUSTEAUAnd my grandfather used to say, people protect what they love. If they don't understand what's going on down below and why it's important to them, whether they're on the ocean front or a thousand miles away, there's no way for them to be able to act in and change the impacts that we have on this life support system we call the oceans.

COUSTEAUIt's devastating in some ways if you talk only about the bad news. There are a lot of efforts being done not only by experts but also by communities around the world to try and change that. And we need to really focus not just on where we're headed right now but where we could be headed if we start protecting those oceans.

REHMIndeed. And you're listening to "The Diane Rehm Show." Fabien, from your first-hand experience though, are you optimistic that we're moving in the right direction to care for our coral reefs in the future?

COUSTEAUYou know, if I didn't have hope I don't think any of us would be here talking about it today. I believe we all hold a little bit of hope despite the fairly stressful news that we hear day in and day out. It's counterbalanced by the fact that youth today know a lot more than we did at their age about our environment, about our -- even about our oceanic world. And to be able to bolster that and really communicate with them so that they may communicate with their parents and grandparents, I do see that we have some traction.

COUSTEAUEspecially in the last few years with regard to the oceans, there's been more positive information, more positive outcomes such as the recent announcement by the Obama Administration to expand one of the marine protected areas in the Pacific. But we have a long way to go and we need to keep doing that.

REHMAnd let me ask you this. Suppose, just suppose all the coral reefs disappeared, what would that mean to us as human beings, Fabien?

COUSTEAUWell, I mean, just on a heartfelt level of course it would be devastating. On an aesthetic level it would certainly be harder to tell pretty, nice stories about the coral reefs.

REHMSure.

COUSTEAUBut I think on a very real pragmatic level it would have a devastating impact on our economy, on not only the health of the ecosystem that depends on the coral reef but on our very own health. Because if we continue treating the oceans as an endless resource in a garbage can, it will come to bite us in the rear end. And it has already in many ways. We just haven't equated those things yet.

COUSTEAUI don't want to venture to imagine that because I've seen human beings create miracles when pressed to task. I believe we have about a decade -- I think all of us think about that -- a decade or so to impassion folks around the world before we do see the worst case scenario with our oceans, with the coral reefs.

REHMAll right. And Mark Eakin, what could happen if they were to disappear?

EAKINWell, first of all, we have to think about some of these things Fabien was just describing that are the important things we rely on. Tremendous ecosystem services, they're provided by coral reefs in terms of fisheries, in terms of shoreline protection. It's been shown that from -- whether it's storms, whether it's tsunamis, those coral reef structures are very valuable in protecting shorelines.

EAKINAnd the other is the economic value that Fabien mentioned. And, you know, if we think scientific numbers sometimes are squishy, you know, economic numbers can be really interesting. But somewhere in the hundreds of billions of dollars a year is what the value of the services that we get from coral reef ecosystems, much of it in terms of food. At least a half a billion people rely on fisheries from coral reefs as their main protein supply.

EAKINBut then the last one is getting back to where Fabien started. And this is the biodiversity. People often refer to coral reefs as being the rainforest of the sea. But in reality the rainforests are less diverse than are the coral reefs of the land.

REHMInteresting. Mark Eakin and Fabien Cousteau. I want to thank you so much for joining us. He's an oceanographic explorer, conservationist and documentary filmmaker. Short break. Stay with us.

REHMAnd just before the break we were talking about what would happen should all the coral reef disappear. And I know that you, Andy Revkin, wanted to add something to that.

REVKINWell, one of the things we haven't mentioned yet is that it's fine for us in the United States and other prosperous places to talk about the value of education and, you know, conservation in dealing with these reefs, getting -- making sure they're vibrant through the century. But in the world's poorest places, particularly in Southeast Asia and parts of the Caribbean, where there's still poverty, if you're not addressing the roots of the poverty that drive people to fish whatever's -- fish to the last fish, then you're going to have some problems as well.

REVKINAnd -- but this gets back to the optimism. You know, at Pace University I teach communication courses. We do films now. Each year we travel somewhere and make a film about sustainable resource management. And one we did -- the first one we did when I joined the course in 2010 was on an innovative shrimp farming method in Belize, where the effluent, the -- basically the poop from the shrimp, the dirty water doesn't leave the shrimp farm anymore. It doesn't go offshore and damage Belize's extraordinary coral reefs.

REVKINAnd so finding way to do aquaculture in ways, for example, that don't damage the ecosystems can give people income and have -- you can have your reef and eat your seafood, too. That's exciting. And because of this paper, next spring we decided our course -- we're going to go to Curacao and film about coral conservation and restoration efforts there, which we've heard great things about from people in other studies.

REHMThat's terrific. Nancy Knowlton, do you want to add?

KNOWLTONWell, I agree complete with Andy. I think one of the most memorable dives I made in the last year was in the Philippines. And this is a country where, in fact, there's been quite a lot of efforts to create small protected areas. But the poverty has really overwhelmed the situation. And I watched a fisherman throwing his net from the shore, having just come from a dive, where in 45 minutes I didn't see a single fish.

KNOWLTONAnd I asked my host, well, what does that person have -- what can he catch? And he said, "Well, analyses suggest that he can fish for an hour and the total caloric value of what he'll catch is about equal to a can of Coca-Cola. So unless you address that root poverty, as Andy suggested, it's very, very hard to manage reefs in sustainable fashion.

REHMMark, do you want to add to that?

EAKINThis is one of the basic problems when we're dealing with some of the things like addressing the overfishing of parrot fish. Where you get to places that the only fish that they tend to have remaining are the ones that don't get caught by hook and line and are only caught by nets and traps and so forth, like the parrot fish. Or people are going out and speaking the parrot fish. So if we don't address that root cause of poverty, if we don't provide alternative livelihoods, we have issues.

REHMHow large is the parrot fish?

EAKINAnywhere from six inches to nearly three feet.

REHMReally?

EAKINThere's some big ones that are just…

REHMI see.

EAKIN…absolutely beautiful.

REHMI see. And what do they look like? Quite colorful, I would imagine.

EAKINYou know, some of them are kind of drab and mottled color, but especially some of the males are just absolutely beautiful, vibrant blues, multi colors.

REHMWhy is it that the males of birds and of fish species get all the color? Here is a fascinating question from Sherry. She says, "I've heard you could donate your cremated remains to help build the coral reefs. Is this true? And if so, who might you contact?" Mark?

EAKINYes. There is a program. I seem to recall it's called Eternal Reefs. It's an off-shoot of the company that makes these concrete structures called Reef Balls. It's an idea of putting out artificial structures to give fish homes when the corals aren't there, more than anything else.

REHMI see.

EAKINIt's not a good substitute for coral reefs, but, you know, it's not a bad way to go after you're gone.

REHMAll right. And here is one for you, Andy Revkin. It is from Victoria, who says, "I was a support diver for NOAA's Hydrolab in St. Croix, back in the early '90s, where the subject of research was the effect of excrement from fish that spent their nights sheltered in coral reefs, particularly parrot fish. The scientists found quite significant deposits of beneficial nutrients brought to the reef in parrot fish poop." So there you are.

REVKINOh, well, the full life cycle of all the organisms in an ecosystem is vital to follow. There is -- poop matters. There was a recent study showing that whale poop actually is an incredibly valuable distributor of nutrients in the deep ocean, and in a way that was, of course, mostly lost when we had our whaling binge. And now there's signs that that could actually be a value to sequestrian carbon in a long run on…

REHMI see.

REVKIN…a small scale. So, yeah, we follow the poop trail. That's really important. I've seen parrot fish pooping out, basically, sand. And it's fascinating to watch.

REHMAll right. Let's go to Toledo, Ohio. Hi there, Paula. You're on the air.

PAULAHello. I'm calling in today because we just went through a major water crisis up here in Toledo and could not drink, use, even boil the water for…

REHMQuite right.

PAULA…two days. And agriculture runoff was largely implicated in this situation, which is a precipitate of the algae blooms in the Great Lakes here, especially in Western Lake Erie. I'm wondering to what extent agricultural runoff is a factor in what's happening in the coral reef situation and also just in the general health of aquaculture in the Gulf as whole.

REHMNancy?

KNOWLTONWell, certainly in some places agricultural runoff can hugely detrimental effects. It's been best studied, in fact, in Australia where the Great Barrier Reef has -- the reefs that are close to the shoreline have been -- have lost a lot of live coral. And the agricultural runoff is one of the primary culprits. It depends on the place. Some places have lots of agriculture and some places don't.

KNOWLTONBut where you've got a lot of agriculture, and a lot of rain taking the products of the fertilization into the sea, then you get the potential for catastrophic loss of reefs. In fact, Barbados -- many of the reefs were lost long before this study even started. I mean the dates -- the first dates of the study -- from massive agriculture.

REHMMark?

EAKINAnd not only does this become a real problem where you have a lot of agriculture close to reefs, and you have runoff from -- whether it's agriculture or even from highly fertilized golf courses and manicured lawns at hotels. But the distant sources are huge as well. And not in impacting the coral reefs so much as other parts of the marine ecosystem. We have these huge areas where the amount of nutrients are causing a major growth of organisms that are depleting the oxygen and leaving these anoxic or lack of oxygen zones or dead zones.

EAKINOne of them in the Gulf of Mexico is quite huge, off of the Mississippi. And there you're looking at origins of nutrients from places like Illinois, Ohio, Iowa, you know, way upstream…

REHMWow.

EAKIN…that the excess nutrients get washed all the way down and they're flowing through, but once they get into the Gulf of Mexico they settle in, they cause this growth of life that uses up the oxygen. And you then end up with a place where almost nothing can live.

REHMAll right. To Charles, in Little Rock, Ark. Hi, there. Charles, are you there? Let's go to Justin, in Riverhead, N.Y. Hi there.

JUSTINHello.

REHMGo right ahead, sir.

JUSTINHi. I am a professional coral farmer. I have -- I co-founded a company called ReefGen. And we're partners with Long Island Aquarium. And my question for the panel is where do they see private entities and basically skill sets, such as ours, playing a role in restoration? This fall we have a campaign called Reef Generation that's kicking off in St. Martin.

JUSTINAnd one of our partners is Dr. Eugene Kaplan. He's written several Peterson Field Guides. One is for the coral reefs of the Caribbean and Florida -- and several industry professionals, as well as a student. And so my question is, for the panel, where they see specialties like ours -- basically what we have to do is grow coral really fast and really efficiently and, you know, I could see that helping very, very, you know, being a beneficial aspect to the -- what's happening on the governmental side. And (unintelligible) …

REHMAll right. Andy Revkin?

REVKINWell, I guess what I would say is this is like climate change. This is an all-of-the-above challenge. There are going to be places in the world where poverty alleviation, finding ways to employ people that don't require them to fish on a reef is priority number one. Places where propagation of coral artificially, you know, whether it's for the -- the value is for the jewelry trade or whether it's putting in place an actual protected area, you know, whether it's a park or marine-protected reserve, this is a problem that's big enough that you need all of the above.

REVKINAnd just to give you a sense of, you know, artificial reefs, too, whether they're burials, a device or something or whether it's the abandoned -- in the Caribbean, in the -- I mean, the Gulf of Mexico, some of those richest, most active zones for fish are around old oil drilling rigs that are now abandoned. There's one that they wanted to turn into a diving camp that I wrote about a few years ago. So, you know, we need it all, basically.

REHMMark?

EAKINSo one of the things that used to be a major problem for -- was the amount of coral that was harvested for the curio trade, for the aquarium trade and other things of that sort, where a lot of coral would be damaged to get a specimen that was, you know, in good enough shape to bring back and use. And it was a major problem in the aquarium trade where a lot of damage was being done. Now, through the kind of operations that he's describing, there are a lot of corals that not only are broken, fragmented and grown up, but there are even corals that are being bred and propagate that way in aquaria.

REHMBut how are they different? Or are they absolutely the same, Nancy?

KNOWLTONWell, they're the same in the sense that they come from -- originally from corals in the wild. But you can certainly selectively breed corals. And people are quite interested now in looking for strains of corals that might be resistant to future climate change. So they're the same, but they can be chosen for particular uses.

EAKINThe other thing is coral's of certain types, especially the branching corals, will grow very different forms depending on where they are living. So two corals can look completely different, be the same species. So if you take something that's used to a wave-swept environment and you grow it in an aquarium, it may look different and may be more valuable for the aquarium trade.

REHMMark Eakin, coordinator of the Coral Reef Watch Program at NOAA. And you're listening to "The Diane Rehm Show." And now to Lambertville, Mich. Hi, Tim.

TIMHi, Diane. Hi, guests.

REHMHi.

EAKINHey.

TIMThere is hope. The thing is it's going to take a heck of a lot of energy to fix this problem by this plan. It involves heating -- first mining and then heating land limestone deposits, which is going to take an enormous amount of concentrated heat to accomplish that to make CaO, quicklime, and excess carbon dioxide. We can then return the quicklime to the oceans, probably by reacting it first with water to make calcium hydroxide. The problem then is what we do with the excess CO2.

TIMIf we've got enough energy, we can dissociate that CO2 and react it with electrolyzed water. Both of these things are going to take an enormous amount of energy. Those reactions will make oxygen and hydro carbons.

REHMAndrew Revkin, do you want to weigh in?

REVKINWell, to do that on -- well, it's a tough arena. The -- there's a geoengineering aspect of what was described. If you wanted to do that any scale that would be meaningful to global coral health or to ocean chemistry, the unanticipated consequences of large actions like that, that are, you know, it's such a complicated system -- become very hard to model. I've written -- been writing about this in relation to iron fertilization, efforts to pour iron dust into the sea and stimulate salmon runs and plankton growth.

REVKINAnd it's a very complicated -- including the chemistry gets complicated. The things that you think might sequester carbon dioxide, can actually release more carbon dioxide if you don't get the chemistry right. So they're all the things that are important to study. That, I think, would be a long ways down the line before -- and then again, of course the energy, where does that energy come from in an energy constrained world. You know, it's hard enough for us to figure out how to get to the energy needs we need for 7 billion, going on 9 billion even now.

REHMMark?

EAKINThere are some interesting things that don't require us to produce more energy to do this. We're already producing far too much carbon dioxide. There are some approaches where you can take the excess CO2 that's already coming off of power plants, manufacturing, etcetera, pipe it to plants where you can take existing limestone -- you can do something called advanced weathering of limestone.

EAKINThat takes that CO2, uses it to breakdown the limestone produced by carbonate, add that into the coastal zone, and on a local basis that can help to offset some of the ocean acidification problem. So it's -- there are some things. How well it can be ramped up to large scale is another question. But there are creative approaches.

REHMNancy?

KNOWLTONAnd to bring this back to the report, there are some things we know how to do right now, immediately. We know how to control water quality and make sure the water's clean for corals. And we know how to control fishing in a way that's conducive to having healthy coral reefs. And those are things we can do immediately, we can do locally, we can do now.

KNOWLTONAnd so I think that's really one of the important messages, is that while we struggle to cope with the bigger picture of climate change, there's -- we have a lot in our toolbox that we can deploy immediately. And that's -- will have an enormous effect on the health of coral reefs into the future.

EAKINBut you know, Diane, this is one of the things that we really haven't been hitting on, is that we do need to do all these things now, but at the same time we need to get going on the problem of climate change. Because if we don't start working to reverse the problem of the excess carbon dioxide and other heat-trapping gasses in the atmosphere, we're not going to get there.

REHMMark Eakin of NOAA, Nancy Knowlton of the Smithsonian National Museum of Natural History, and Andrew Revkin, he writes the Dot Earth blog for The New York Times. He's also senior fellow for environmental understanding at Pace University. Thank you all so much.

EAKINThank you, Diane.

REVKINThanks for having us.

KNOWLTONOur pleasure. Thank you.

REHMAnd thanks for listening all. I'm Diane Rehm.