IRA FLATOW: This is Science Friday. I’m IRA Flatow. It’s climate week here in New York. So we thought it would be a pretty good time to focus on our climate crisis. And a good place to begin– the waters surrounding South Florida because the coral reefs, they are suffering terribly from the effects of climate change. Coral reefs are important for a couple of reasons.

They protect coastlines from storms. And they’re an important part of the oceanic food chain. We talked about this on the show back in July about how South Florida’s waters reached abnormally high temperatures, some over 100 Fahrenheight this summer. And it turns out, as you might have guessed, that these high temperatures are not good for the health of the coral.

My next guest dove beneath the waves on one of Florida’s reefs and is here to tell us what he saw. Benji Jones, environmental reporter for Vox based in new York, welcome to Science Friday.

BENJI JONES: Thanks so much for having me, Ira.

IRA FLATOW: Benji, the last time I went diving in that area, it was very disappointing. And you recently went on a dive to check out Pickles Reef. Tell me what you saw down there.

BENJI JONES: Yeah. So I was down there in early September. And really, when we pulled our boat up to the reef, it was already clear that there was a problem because we could see these bright white patches shining through this kind of beautiful blue ocean water. And then when we dove down to see what that was, we saw these big groups of elkhorn coral, these kind of moose antler-like coral, and they were just stark white because they had bleached.

IRA FLATOW: And now this isn’t the first time you’ve dived this reef. You were there, what, in the spring of 2022. I imagine you must be seeing differences between those two times.

BENJI JONES: Yeah. That’s what made it such a kind of devastating experience, diving in September, because I had been there with the photographer Jennifer Adler back in April of 2022. And we had seen these beautiful reefs that different organizations were working to restore. And there were these meter-wide structures of coral in brilliant orange, and brown, and green. And it was really beautiful.

And then to come back and see what has happened after this summer, it was really heartbreaking. And the people that we talked to who were doing this restoration were really sad about it, as you can imagine.

IRA FLATOW: Yeah. We’re going to get into the restoration next. But tell me why this is all happening. What does warm water do to the coral that makes it unhealthy for them?

BENJI JONES: Yeah. So excessive heat over a long period of time causes a very fundamental relationship between coral and a type of symbiotic algae that lives inside of it to break down. So when you look at a healthy coral, it’s very colorful. Coral reefs are famously colorful.

And most of that color comes from a kind of algae that lives inside coral tissue. And that algae not only makes it beautiful but also gives coral its food. And when the water gets too hot– in the case of the Florida keys, it’s about 85 degrees or above is considered too hot– then that relationship breaks down. The algae leaves the coral. And what you see, that white color, is because there’s no algae there.

And you’re seeing straight through the coral tissue to its skeleton, which is just calcium carbonate. So it is essentially starving. The coral is starving when it looks white.

IRA FLATOW: Well, Benji, thank you for sharing the bad news with us.

BENJI JONES: I wish the dives were a little bit better. I wish the reef was a little bit healthier. But yeah, I’m glad to be able to chat about it.

IRA FLATOW: Yeah, don’t we all. Benji Jones, environmental reporter for Vox based in New York. And you can read his full story about Pickles Reef on vox.com.

No one wants to just sit back and watch the corals die. So can we restore Florida’s ailing reefs? Some biologists are trying to do that. Andrew Baker is a marine biologist at the university of Miami in Miami Florida. He has been working on remediating Florida’s corals for decades. Welcome to science Friday, Dr. Baker.

ANDREW BAKER: Thanks so much, Ira. It’s a real pleasure to be here.

IRA FLATOW: Explain to me, please, the work your lab does to try to bring back these corals.

ANDREW BAKER: So for a while now, we’ve been interested in how corals respond to heat stress and increasingly wondering whether there’s ways to make corals more thermally tolerant using new approaches and kind of novel ideas, and then testing them in the laboratory, and seeing if they will work out in the field. So there’s a few ways that you can do it.

It turns out that there are certain types of algal symbionts in corals that are heat tolerant. And if the corals have those algal symbionts in them, they’re more resistant to bleaching. These algae were discovered during the course of natural bleaching events that happened all over the world, dating back, really, to the early 1980s. And scientists began to discover that corals that had these heat-tolerant types of algae in them actually didn’t bleach and survived through these events better.

And that’s evolved really in the last five or 10 years into trying to figure out if there are ways to get these heat-tolerant algae into corals in advance of a bleaching event and, ideally actually, even in the early life stages of coral, when corals first begin life on the reef, to see if we can seed these baby corals with those heat-tolerant algae to help them survive.

IRA FLATOW: Is that what you’re trying to do in your lab?

ANDREW BAKER: That’s one of the things that we’re trying to do is to provide baby corals, which are produced during coral spawning events by the by the millions, to try to use that opportunity, that sort of bottleneck, where all of the coral’s offspring are kind of together at one point in time, to produce a kind of a scalable approach to seed those babies with the right types of algae and then see if they retain them over time on the reef and, ultimately, grow up into adult corals that do better.

IRA FLATOW: Yeah. How successful have you been at this?

ANDREW BAKER: So in the lab, it’s pretty successful. You can you can seed babies with these heat-tolerant algae. You can grow them up to a few months of age. And then you can put them out on the reefs. And in lab tests, we’ve been able to show that those corals are, indeed, significantly more thermally tolerant than the corals that you provide with the normal algae.

The early trials of putting those out onto reefs are still in the early days. And so actually the bleaching event that is happening right now will be the first natural test of some of these approaches to see whether, in fact, the approaches that we’ve used in the lab to try to produce a field trial actually work. And so we’re waiting to see what happens as this event develops.

IRA FLATOW: What other novel approaches are being used to help save reefs?

ANDREW BAKER: Well, I think recently there’s been tremendous appreciation and understanding of the role that reefs have in protecting our coastlines from the damaging effects of storms and flooding. And even recently, the Department of Defense has recognized that they could use nature-based solutions, like coral restoration, to try to protect coastlines. But you can’t restore reefs unless you’re really trying to incorporate methods for increasing heat tolerance and making those corals more resilient to climate change at the same time.

We don’t want to be just planting out the next set of climate victims and waiting for the next bleaching event to wipe them out. And so the Department of Defense recently invested in a project to build what are called hybrid reefs, reefs that are a combination of an artificial structure on top of which corals are grown to try to make that structure self building and self repairing. But those corals need to be the most resilient, climate-stress-hardy corals available to us. And so there’s been a lot of interest in, can we leverage the huge interest in protecting coastlines and the infrastructure that is saved by doing that into a program of coral restoration that really takes advantage of these new approaches to building heat tolerance into corals and try to scale that up?

So I think there’s a great nexus of opportunity right now between realizing that not only are coral reefs under threat, and they really need a massive effort to try to save them. But our coastlines are under threat. And if we can kind of marry those two objectives, we can actually have a chance at scaling up the solutions that we’re working on at the scale with which they need to operate to have a chance of success.

IRA FLATOW: Now, you’ve been doing this for nearly 30 years. How do you keep hope alive that all of this work will help bring the corals back?

ANDREW BAKER: Yeah. I think it’s a huge challenge. When people have been working for so long and people have been restoring reefs for so long, it’s disastrous to see the reefs that you’ve been trying to restore just die in the space of a couple of months due to an event which, on some level, was entirely predictable. We’ve known as scientists that coral bleaching events are going to happen. This is entirely predictable. The event that we’re seeing now has always been a question of when that event would happen and not so much if that event was going to happen.

But even knowing that it’s predictable and even knowing that this is around the corner, having it actually happen and having it happen with the magnitude that it occurred and the sort of severity with which that hammer came down has been really disconcerting because we had hoped that these bleaching events might accumulate over time. They might get progressively worse. But we were suddenly hit with just a huge event.

So how do you keep hope alive during that? I think a lot of coral biologists who are working in the field are, right now, hit with you know a word that I came across recently, which is solastalgia, which is a word given to the distress or anxiety produced by environmental change, usually on your home environment.

When you see your home environments, the places that you’ve studied and been around for so long, get devastated, it’s hard to maintain a sense of optimism about the future. And I think that’s what solastalgia is about. For me, the tool that I’ve used to try to maintain a sense of optimism for the future is that I remember, when I was a graduate student, going back to the 1990s, people used to tell me here in Florida how wonderful the reefs used to be in the 1970s and 1980s.

And there was a sense already then amongst kind of old timers of what had been lost. And scientists have a name for this idea, which is the idea of a shifting baseline, that new generations of scientists come in. And they have new impressions of what constitutes natural and what constitutes healthy. So when I see what’s happening right now, I take myself back to that time in the 1990s. And I remind myself that, if we could have gone back now to the 1990s’ state, I would have you know traded everything in an instant to be able to do that.

And yet, at the time, back in the 1990s, I was told that the reefs back then were just a shadow of what they used to be. So I think I always try to remember that, no matter how bad things get, the opportunity to go back in time to where we are now in the future is just going to be tremendously valuable.

IRA FLATOW: It’s sort of a sense of, if I don’t do something now, 30 years from now, I’ll be sorry I didn’t try.

ANDREW BAKER: Yeah. It’s how do we avoid this kind of sense of regretful hindsight. No matter how things look now, I know that, in 2045 or 2050, we would give our eye teeth to go back to where reefs are now in 2023, even though, right now, we’re lamenting the losses that we’ve had. So I think we always tend to undervalue what we still have left because we’re always lamenting the loss, mourning the change. But in fact, reefs still hold tremendous possibilities. And we will only realize how valuable they were in retrospect.

IRA FLATOW: Yeah. Well, we wish you great luck for both your work and for the health of the reefs. And we’ll check back with you to see how it’s all going, OK?

ANDREW BAKER: That would be wonderful. Thanks so much, Ira.

IRA FLATOW: You’re welcome. Dr. Andrew Baker is a marine biologist at the University of Miami in Miami, Florida.

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