Coral Reefs

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Hello, welcome to the Infinite.

I did a very special hello, by the way.

That was what we call the podcast hello, which means that because slightly younger people often listen to BBC Sounds for their podcasts, I go, hello.

Can I just explain who that is?

That's Robin Ince.

I'm Brian Cox.

And you are listening to the BBC Infinite Monkey Cage podcast on BBC Sounds, which you know because presumably you've downloaded it.

My wife's family used to own a mermaid.

This is entirely true.

They owned a mermaid and eventually they sold it to a hair salon in North Shields.

And it turned out it was basically an embalmed cod body with a monkey's head stuck to it.

And I have no idea why a hair salon would want that, as if that was going to be kind of one of the tips of what I was.

I was going to ask for a perm, but I think instead, could you make me look like a decaying macaque

um what

what are you talking about well the trouble is that most of this show is it's about coral and it's about the ocean and i've not had any oceanic adventures because you've had loads on the telean in real life whereas uh i have a kind of like well i suppose really i'm allergic to both seawater and jeopardy Richard Feynman once said, the imagination of nature is far greater than the imagination of man, and the oceans offer many examples of the eccentric creations of natural selection, from the blobfish to the blue whale.

But it's not merely the great and grotesque that should fascinate.

What of the microscopic organisms that create great reefs?

Today we have a distinguished panel to discuss the magic and wonder of coral, and they are.

I'm Callum Roberts, Professor of Marine Conservation at the University of York and author of Reef Life, an underwater memoir.

And I think the greatest mystery in the ocean is how really rare creatures find each other to reproduce.

The ocean is just so incredibly vast, and yet the rarities in it are often vanishingly small and they have a really limited range of movement.

So it's entirely possible they spend their entire lifetimes never seeing another creature like themselves.

In fact, for most of them, that's probably what happens.

But enough of them do find each other that the species are able to persist.

And I think that's just an incredible mystery and a wonder.

My name's Heather Coldway, I'm a marine conservationist with the Zoological Society of London and honorary professor at the University of Exeter.

My mysterious fact about the ocean is that over 90% of species in the ocean have yet to be described.

And that's in a world where we tend to think we have so much knowledge and information and facts and we know quite a lot about life.

The fact that you can go exploring parts of the ocean and just discover new species, even entirely new ecosystems, is a magical fact that keeps me engaged in the ocean.

I'm Marcus Brigstock, and I once genuinely accidentally swam with a polar bear.

I agree very much with Callum about rare and extraordinary creatures finding each other for sex.

Having been a goth,

I can attest to how difficult that is.

And this is our panel.

Can I just say, Marcus, the image of a goth swimming with a polar bear is a delight.

It's beautiful, isn't it?

It was a very confused polar bear, I can tell you that much.

I was sailing.

I sailed from Svalbard to Greenland with a group of climate scientists and artists.

And one of the filmmakers on the boat said, I'd really like to get footage of one of us floating between icebergs, a sort of man and the ice thing.

And I was nominated.

It had been a very traumatic journey.

The crossing was horrendous.

I was very sick, and I think I actually didn't eat for three hours on one occasion.

But you can hear this filmmaker, it's great footage: me climbing down the side of the boat, and he says, Oh, there's a seal in the water.

And I thought, Oh, brilliant, there's a seal that'll make the footage even better.

So I then pushed away from the boat, wearing this very stiff survival suit.

And as I push away, you can hear him say, Oh, no, no, it's a bear,

which then changed

its direction in the direction of the boat.

And I was back on board mighty quick.

How do we get rid of the bloke who keeps being sick everywhere?

I have a plan.

We were filming once, we were filming Great Whites just off the

South Australia, the South Neptune Islands.

And so, my director dropped his camera over the side of the boat boat and then jumped in after it when we were filming The Great White Sharks.

Wow.

Which was a genuinely stupid thing to do.

And the film was in his memory.

We put it at the end.

It was all right.

Anyway.

First of all, I'd like to know, Carl, we should really start with the definition because I think a lot of people are still not really aware what coral is.

So corals have fascinated us for a very long time.

Since the 16th, 17th century, people have been wondering what this stuff is that's washed up on the beach of tropical shores.

And

it was the typical question, animal, vegetable, or mineral.

So the things that were dried out on the beach were very definitely mineral.

They were made of the same substance as chalk, calcium carbonate.

But when they were fresh and they'd washed up, then they were covered in this kind of fishy film, which was very animal in its origin.

But people looking over the side of boats through glass bottom buckets would look at them and they'd see this kind of garden underwater, and they thought, well, they must be plants.

We resolved that question by figuring out that they're all three at once.

They're animal, vegetable, and mineral.

And the vegetable bit is that the animal, the coral animal, which is a little bit like a whole colony of sea anemones, contains within its tissues these tiny microbes called zoosanthellae, and they are able to photosynthesize.

And the coral has hijacked them to produce 85 or 95 percent of its food.

So they have to live like plants because they need sunshine, so they're out in the open.

And that's the secret of their success.

Because once they had got this plant working for them, the corals were then able to produce calcium carbonate far faster than anything else in evolutionary history, which means that coral reefs could be formed as geological edifices that can be seen from space.

And these are produced by little microscopic animals, often things that you need a magnifying glass to see properly.

Are they named after Susan Thele, who discovered them?

Zuzanthele.

Zuzanthele, yes.

Do a lot of people not go into marine biology because they go, do you know what?

These pronunciate, I'm going to go into physics.

It's a lot easier, muons and gluons and everything.

Whereas Zusanthelli, it took you about two hours with that this afternoon, didn't it?

No.

Yes, it did.

Yes, it did.

So the calcium carbonate, I suppose, the thing that we think of as the coral reef that we can see, is really really a byproduct or has the animal now sort of evolved in almost to use that structure?

I mean it's part of what makes the coral, it's providing it with its home and its place to live.

And these multiple millions of small creatures, these polyps, together are forming these giant reef structures.

And we also mustn't forget, although we have these incredible tropical reefs, which is the first thing that come to mind, but we also find corals living in the deep seas, we find them in cold waters, and indeed, I think the oldest corals have been found in the deep, which have been recorded up to 4,000 years old.

Are those ones in the deep not dependent on light then?

That's right, yeah.

So they have obviously a different strategy of life, and they don't have the zoosanthellae, so maybe that's another option for marine biologists with pronunciation challenges.

So they're best seen as a colony, essentially, a large colony of

billions of organisms.

Absolutely, yes.

And as Callum said,

the largest living structure on Earth is the Great Barrier Reef, and that's 2,300 kilometers of reef that's in a mixture of islands and this huge, enormous structure that you can see from space.

And that comes from these microscopic animals that are there together.

So it is very much the basis of the coral is the animal, but completely dependent on this plant.

When did they emerge in evolutionary time?

How long have they been on Earth?

So the coral that builds today's reefs got together with the zoo Xanthali about 100 million years ago.

And so we are living within the greatest era of reef construction that Earth has ever seen in geological history.

And that's quite a remarkable point to be at, particularly when, as we will find out later, we are pushing coral reefs towards the end of that era very rapidly.

And of course, within the reefs, you've got this huge diversity of species.

So it's not just one thing.

You think that's what's so incredible about reefs, is they cover less than 1% of the ocean, and yet they host 25% of all species in the ocean.

So you think of the

huge array of life, you probably think of the fish, the sharks, the rays, the turtles,

and then the corals, which sometimes could be seen as the wallpaper, but actually those are the fundamental part of

the life and hosting this incredible diversity.

That's a remarkable statistic.

So, 25% of known marine species are associated with reefs.

Can you give us a, I mean, I was going to say, can you give us an overview?

You can't give us an overview of 25% of all marine species.

I'll give you a list.

I'll start for the rest of the show.

A description of what does a food chain look like on a reef?

How does that build up from the base to the predators?

Well I think it begins with the I mean the coral itself and I think one of the cool things and coming to this evening full of cold I was thinking you know one of the great things about corals is their mucus

and the vast amounts of mucus they produce so they take some of the carbon that they're captured through the algae and then they spit that out as mucus but that mucus then captures all the other nutrients in the in the in the water and then sticks it down back down on the sediment and on the reef so that's keeping the nutrients within the reef itself.

So, it's sort of part of that whole feeding cycle.

So, it starts right at the bottom of the chain.

Then, obviously, the complexity of the reef habitat starts to provide homes for tiny, many tiny invertebrates, and that's where there's your discovery of new species is going to be.

Then, those are starting to provide the food chain through to the fish.

You've got the fish that feed on the algae, you've got fish that feed on the corals themselves,

you've got the fish that feed on other fish, and then you work your way up the food chain.

When you talk about new species, do we see, because people often talk about the fact, I know this is not true, but that you cannot observe, actually in real time, you cannot observe evolution.

But in something on this scale, do we see within that, are we able to see the patterns of how these very small creatures are evolving and changing in an environment like this?

Well, we do know that things are evolving quickly on the reef, and one of the things which is incredibly potent as a selective force is predation.

So reefs look like they're really benign places to live and everything's bobbing around.

You know, if you've watched Finding Nemo, everyone's getting along incredibly well, even the predators and the prey.

And

that's true.

If you look at the reef,

there will be tiny little fish just dancing around within inches of the mouth of a huge grouper and the grouper's sitting there in its hole eyeing it but not really bothered to move.

And you think, well, why is that?

Why doesn't this fish snap up these insolent little prey items?

And the answer is that because the prey items know that the grouper is there, the grouper knows there's no point in it actually trying to catch them because they will lose.

The prey will win.

So, what you see is this kind of illusion of a benign place, a happy place.

But in fact, acts of predation are incredibly quick and fleeting.

So you could be down there for hours.

I've seen exactly that happen in a nightclub in Cardiff.

Same system.

I'll stop there.

I'm fascinated by that and by

some of the stuff you see on Reeve.

I mean, look, I know it wasn't made for my benefit, but box fish.

How was there an evolutionary advantage to effectively becoming a slow-moving cube that's bright yellow,

that everything can see, that doesn't really function like a fish does because it can't move its body properly.

It can only do its tail and side fit.

I mean, it can do jazz hands like you wouldn't believe.

But I cannot imagine when I look at them, what was the evolutionary advantage of turning out like that?

And also, for the audience listening on the radio, that was a superb box.

Thank you.

I did jazz hands down by my hips and did a bit of a shimmy.

And look, yeah, tried to look as cunning as possible.

Yeah, that I can pull off pretty easily.

But I think

that is what has to happen on a reef, is that things have to get specialized into

niches that you wouldn't have quite imagined that they could exist.

I think Marcus is asking, what is the niche?

The niche is, firstly, they would get stuck in your throat because they're solid and they're square and they're not that tasty and they're saying by being unusually shaped and brightly coloured, that that's a warning that you're not that good to eat.

So it is the colours and the patterns, and then you get the complexity of the things that are saying that because they're genuinely not good to eat, or they're

you know, they've got toxins or spines or whatever, and then the things that pretend they're like that, but aren't really.

And then you, I mean, my first foray of research into coral reefs was on the seahorses, and that is as crazy, that would involve a different set of jazz hands, but you know, that is an extraordinary,

as people have said to me, alongside our corals, rocks, or plants, is

seahorses are far too cute to be a fish,

which is that same thing as becoming adapted to actually be very good at camouflage, changing colour, hanging onto a piece of coral or a sponge or something on the reef, and being perfectly camouflaged, waiting for that moment with your independent eyes moving just like a chameleon until a little shrimp swims past innocently and then sucking it up with your straw-like mouth.

So there's all these incredible behaviors,

specializations that if you're going to cram in that many species into that small an area with that much life, you have to do that, and that applies right to the smallest level.

So, you know, a brand new coral larvae arriving on the reef, settling down and working out where it's going to start growing, is quite a big challenge if you think about how full a reef already is through to the species that depend on it.

Yeah, and Callum, your introduction was fascinating: this idea that there are animals on the reef that appear never to meet another of the same species.

So, what I mean, you said it was a great mystery, so my question is almost redundant, but w how if you speculate, I mean, what is happening?

It seems completely counter to what you would expect.

I mean, It can't breed, basically, because it never meets anyone else.

The thing is that if you go out and you sieve every little piece of sand on a reef, if you turn over every rock, if you take things apart, as some scientists have done in places, and looked intensively, then you can find...

pretty much all the species that are there.

And this group of scientists went to a reef in New Caledonia for a period of about 10 days, and they did nothing other than search for snails and clams.

And they found thousands of species of snails and clams, different ones, and about half of them were

only represented in their sample by a single individual.

And so they were exhaustively looking for everything that was there.

And if they could only find one, well, what could that poor animal find in the way of a mate?

They would just never have a chance.

It would be like stepping out of your front door in London and thinking, will I find a soulmate today?

But not with the option of hundreds or thousands of people that are all the same as you, but just will I find any creature that is the same as me at all?

And the answer for most of them has to be no.

But there's this little quirk of reproduction, which means that a few individuals that find each other may be responsible for the great majority of the reproduction from one generation to the next.

And geneticists found out that when they sampled

the genetic makeup of newly settling clams from the plankton, you know, they have a planktonic larval stage, so the eggs float off, then they hatch into larvae, and the larvae eventually settle onto the bottom.

When they sampled those, the effective population size was a few dozen individuals across the whole of this huge area of coast.

And so you literally might have your entire reproductive output dependent just on these chance meetings.

See, I think it's a rather beautiful vision because the state of humanity at the moment,

and I woke up and I couldn't find any of the same species as me.

It was lovely.

I had the library all to myself.

Marks, I want to ask you when you've become very interested in the environment, really, and quite active in the last kind of decade or so.

Do you remember when, what was it for you

where that story really begins?

Well,

I got tipped over into it by mistake, really.

I mean, I suppose, like a lot of people, I just didn't know very much about it.

And I think the thing that turned me on to climate science actually was the resistance to it.

That's probably the mindset of a comedian, really.

But I was reading unbelievably stupid stuff by people who were willing to put a photograph next to their, like, next to their name.

So then I started doing broadcasting a bit about my very shallow understanding of it and I got scooped up by climate scientists going

you'll do and then I then I did this sailing trip from Norway to Greenland and then a year later up the west coast of Greenland.

So that was what threw me in.

I'm a level one cheese judge.

I mean I am genuinely

I'm a level one master of cheese.

So you know in terms of the climate it's my fault.

At least we got to the bottom of that.

Yeah, yeah, yeah, yeah.

It's me.

It's me that's done.

How many levels of cheese?

Two.

Oh,

so I'm halfway there.

One's where you start, so two's better.

Two is better.

Two's much better.

Yeah, two.

You love two.

Two's all about the molecular bonding process of how milk becomes cheese.

I don't need to know that, but I can tell you an excellent Stilton when I see one.

Heather, you're going to have a choice of answers now.

You can either, I will ask you a question on your favourite cheese, or we can talk about the mysteries of reproduction in coral.

Which would you prefer?

Probably to stick with the corals if that's what I've got.

That's fine.

Okay, but I'll bring you a cheese.

Do you want to give us the cheese as I got or not?

That's

my favourite cheese.

Yeah, you don't have to, though, there's no pressure on that.

Cornish yag.

Brilliant, that's over and done with now.

Let's go on to the reproduction.

All right, excellent, thank you.

Wrapped in nettles, of course, and named after the mats.

I'm really going to have to get you off the cheese now.

To bring it back to the subject, The question is: how do coral reproduce?

So, corals have a couple of different strategies, and one of the most spectacular, I think,

features of them is the broadcast spawning.

And that's basically if you're stuck on a reef and unable to get to a Cardiff nightclub,

then you have to think of something else.

And so, at that point, it's a case of releasing your packets of eggs and sperm into the water.

And

what's particularly spectacular is that you can pretty much set your watch by when that's going to be for a certain species in a certain location at a certain time.

So it usually happens at night time, so there's a combination of lunar cycles, of the sea temperature cycles, and then the time of day or night.

And at that point, you have a certain species will release these bundles, they float up to the surface, and then they will slowly break down.

And if every colony of that species in the area is releasing at exactly the same time, and then all accumulating into this particular area of water, when they break down, then they start mixing up, and that's where you're getting your sexual reproduction.

And so, this is an extraordinary sight to see as a scientist is when you actually get in the water, and it's this spontaneous emergence of these packets that you suddenly see starting to pop off colonies, floating a bit like in a snow globe, but heading to the surface to form these great slicks of reproduction.

And is this just on a particular day or a particular time of day, once a year, essentially?

Yes, exactly.

For some species, it is a once a year

happening, and obviously, scientists are slowly growing their knowledge of the different species in different locations about when that happens.

And that's particularly critical in understanding about how

reefs can persist going forwards into the future.

The other way that

reefs corals can reproduce is, I guess, more plant-like in terms of asexual reproduction, and that's basically through a storm damage or being knocked or whatever, that a bit breaks off, and if it lands somewhere suitable, then it can grow again.

Or if a colony gets big enough, then it starts budding off new corals that are exactly the same as the parent colony.

This is a remarkable idea because you're talking about reefs now that may be

hundreds of kilometres or more across, but there's a synchronisation

which can be almost, as you described, to the hour.

Yes, to the minute.

I mean, people, you know, the scientists who are

studying those particular spawning, mass spawning events, are planning around the particular time on that particular date and getting everything organized and ready to be there at that particular point in time.

How does that synchronization occur?

Do we have any idea?

It is that combination of the changes, the natural cycles that you get in temperature,

the lunar cycles that you get, and then the

daily cycle that you also happen.

So these things are coming together to cause that synchronization in timing.

And it's a perfect strategy to enable that sexual reproduction and that's really going to ensure the evolution of corals over time.

How's a lunar cycle?

I mean what's the mechanism?

Is it moonlight?

Is it what?

That's a very good question and I'm now bubbling out of my depth as to what exactly it is about the lunar cycle because that's all also turned you know mixed up with the tidal cycle which the the corals can sense very strongly but but what's curious about this mass spawning is that when you're there, it's not just the corals that are going off, it's all sorts of other things.

So there are these little starfish that are crawling their way up onto the tops of corals and then bursting out with these bright red caviar droplet eggs.

And then polychaetes, these worms, are rushing out of all the interstices of the reef and flying past your mask.

And as they do so, they're literally ripping themselves apart and releasing a body full of eggs in this kind of final act of self-sacrifice that they do.

And they often self-sacrifice themselves into your ears as well, which is extremely unpleasant.

But

the whole of the water in front of you is just full of reproducing organisms.

And things eating reproducing organisms as well.

Yeah, I was going to say, I mean, this is right back at Cardiff.

We should say

the sacrificial element of it, just literally ripping themselves apart in order to find a mate.

I've seen that take place.

Well, I know that you own that big yellow jacket with shoulder pads, and that makes you a lot safer, doesn't it?

When you're a boxer in yellow, everyone leaves you alone in that nightclub.

I don't know who he is, but I'm not going near him.

I've done some, I did a bit of coral planting.

You know, you were talking about how some of them like break off.

And you can, there was like

a metal frame, it looked very much like an umbrella, and then we really carefully underwater attached pieces of coral to it.

And the project's been really successful in the Maldives, and

it's

one of a few ways in which tourism has been turned slightly eco-is you can plant your own reef and then they'll film it for you and send you an update so you can see the reef growing, which I have to say does happen fairly slowly.

We've talked about the

wonder of these ecosystems, but it's also been, as many people will know, widely reported that the reefs are under threat.

I suppose the Great Barrier Reef is the most worrying example.

So, what is the extent of that danger now, and what is causing it?

I mean, corals are one of the most vulnerable ecosystems on the planet, and they are definitely the canary in the coal mine for what's happening to the ocean more generally.

We have lost 20% of coral reefs in the last 20 years, and we are on a very dark trajectory of losing all the coral reefs by 2050, if things don't change.

We're talking about shallow coral reefs in tropical climates living this really delicate balance that's dependent on things like temperature.

And as that changes, the whole relationship between that beautiful thing called the zooxanthele and the animal also changes.

And it goes from a beautiful symbiosis to a kind of anxious-hate relationship where the coral polyp spits out zooxanthellae algae, and we get this event called bleaching, where literally the colour disappears from the coral and they look physically white.

If the temperature doesn't change quickly, then the coral then dies, and that's been the major cause of loss of coral lives and is the major challenge going going forwards for them.

Yes, I'd read, Callum, that in the was it 97-98 in the El Niño, 95% of the reefs in the Indian Ocean were lost.

70 to 95% of the coral.

So that's the thing.

Often coral and reef are conflated in these sorts of things.

The reefs will still be there.

The corals may not be alive on them.

And so the structure that has been built over 10,000 years is going to persist for a lot longer than the coral.

So we're losing a lot of coral from reefs in each of these warm water events.

The thing is, the oceans are very, very good at absorbing heat, and of the heat trapped by greenhouse gas emissions since the onset of the Industrial Revolution, 93% of it has been taken up by the oceans.

Now, that's incredibly lucky for us because if it hadn't been, the temperature on land would not be a degree centigrade warmer than it has been in the historical past.

It would be 36 degrees warmer.

And

if you measure the amount of heat which is being trapped by the oceans every day,

it's equivalent to

something like three to six Hiroshima-sized bombs being exploded in the ocean every second.

So that is about a quarter of a million nuclear bombs exploded on the Earth every day.

day.

That's roughly the extra heat being added.

So all the climate change deniers out there, try and get your heads around that one.

and yet if you swim off Scarborough it's still incredibly fresh

the other thing I learned about this when I went to the Arctic is that the

the function of that the sea ice serves with with huge levels of salinity in cold water that sinking rapidly to the bottom and drawing warm water across the surface and that as the sea ice disappears that process becomes warped and and it's very hard to predict exactly what that will look like.

I remember being told, though, that Edinburgh is on the same latitude as Anchorage in Alaska, which people will have seen pictures of or perhaps even been to.

Edinburgh and Anchorage are on the same latitude, and Edinburgh is kept as temperate as it is by the top of the North Atlantic.

Yeah, that's what keeps it temperate.

And as soon as you start changing that system, it's very hard to predict what will happen then.

Well, it's happened in the past, so you can see what happened, and that is it got a lot colder in the North Atlantic.

And there was a period when there was a big ice dam broke from North America, which led to a flood of fresh water into the North Atlantic, which reduced the rate of sinking, which reduced the pull of warm water to the the north and it caused this little ice age, the younger dryass.

And this is a period where the earth cooled right down again in the North Atlantic region at least.

And that's often thrown about by climate change deniers.

We've had ice ages before, and I always think, yeah, but we weren't here then.

I mean, I don't want to be here for that.

It sounds awful.

I like skiing as much as the next man.

Let's be honest, I like skiing as much as I like cheese, which is a lot more than the next man.

But I think it'd be very good.

Cheese rolling on a sled, that's your favorite thing of all the people.

It literally is nothing better than that.

I wondered about talking about the actual, apart from coral obviously being a very clear marker of dangerous change, but when you actually also see this dying, those around coral, what effect does that then have, the ramifications for the ecosystem as a whole?

I mean, I'm sure that the loss of that, therefore those other things around it as well, the ramifications, it must go on and on.

Absolutely.

You know, we

when you've got that dependency on the corals at the base of that system,

then obviously if those corals die, there's a huge consequence

for the life that lives on them.

So, you'll see some species that eat corals obviously were going to be the first to be affected, but over time it's going to run through that food chain.

So, you see lag effects after coral reefs or the corals in a reef system

are killed by a bleaching event,

then you'll see the immediate impacts on some species and then slower impacts on others.

But obviously, when you've got that degree of dependency for all of that biodiversity, the ramifications are huge.

And we also mustn't forget how incredibly important coral reefs are for

billions of people around the world as well, in terms of a massive source of food security.

That reef structure is providing protection in terms of stopping waves from smashing into the shore.

And

we've got this incredibly important system for a wide variety of reasons that is at risk.

And

a dead reef erodes far quicker than a growing

reef that's that's still got its structure and function.

Have

any types of coral proved to be more resilient to the change?

Yes, and I think this is

moving forwards in a more positive way.

Firstly,

we really need to protect our coral reefs and we know that if we protect them, we're buying time.

We're not solving the problem of climate change, but we're taking the pressure off those really important systems, and that's absolutely critical.

And we know in places like the Chagos Archipelago, where I work, that

where you have a fully protected system,

where it doesn't have other threats from overfishing or coastal development or population pressures, that it can bounce back quickly from, and when I say quickly, I'm talking about a decade of recovery but it still can fully recover but what's happening now is we're seeing these warming events and the consequent impact on corals happening

over you know more severely over shorter time periods so it's instead of being something that happens you know once every you know decades it's happening every few years and so there's no chance then for the reefs to recover so we've just been through yet another global bleaching event, 2014 to 2017, and we're still understanding the ramifications of that now.

So, how are things, you know, how are the corals going to recover?

And that's where we've been so devastated by the news of the Great Barrier Reef, where half of it's dead.

So, Carlum, I mean, that's the real battle, isn't it?

Which is it's not changed at this speed before.

That's exactly it.

And if you look at the great extinction events in planetary history,

most of those were associated with a large-scale release of carbon dioxide into the atmosphere, which led to runaway global warming, which led to acidifying oceans and too much heat, et cetera.

And so there were a lot of extinctions that happened as a result of those.

Now, the present rate at which we're releasing greenhouse gases into the atmosphere is about eight gigatons per year, whereas

the big mass extinction event, the end-Permian mass extinction, was about 0.6 gigatons per year.

So we're looking at a very intense spike in release of greenhouse gases into the atmosphere, which is driving climate change at a far more rapid pace than before.

It will take us a very long time to get to the total amount of carbon released at the end-Permian mass extinction.

So we do have time to change course, and we do have the opportunity to mend our ways in time to save many ecosystems.

It looks like coral reefs will struggle regardless of what we do, that there is

no easy win to saving them now.

And I think that's one of the lessons here is that coral reefs may already be too far gone for us to rescue them in the state.

to which we inherited them from previous generations and the the wonderful movies that Jacques Cousteau made which look incredible today and but are increasingly scarce.

You'd have to go further afield to more remote places to find bits of reef that look like the ones in Jacques Coustea's films.

And in 80 years' time, it will be much, much more difficult to do that.

That's not to say there's no hope.

I mean, you were asking about evolution earlier, and evolution is happening on the reef.

We know from experiments in Hawaii about 40 years apart, people stressing corals with warm water.

And in the 70s they did it in order to find out what the effects of power station effluent, cooling water effluents would have on coral reefs.

Today they're doing it to find out whether there's been any evolution of those corals to the warming of the ocean and there has been.

The corals bleach

less quickly and at higher temperatures now than they did in the 1970s.

So there there is some resistance building in there, but the bad news is they're not doing it as fast as the temperatures are changing.

So we've got

evolution underway.

Now there are other slight glimmers of hope, which is one of which is that we do find corals in places with really hot water right now, in places like the Arabian Gulf, for example, or in tide pools on Pacific Islands.

And these are extreme environments that some corals have adapted to well.

And there is a whole kind of sub-field of science now looking at what it is about those corals that makes them resistant to these temperatures.

And can we somehow engineer or assist evolution to promote these characteristics in other corals in other places?

At the moment, I think it's science that's really worth doing.

We're going to find out a lot of stuff along the way, but I don't think it's a cure for the problems at Ale Reefs.

The number one thing we have to do is to transition to a carbon-neutral economy.

Marcus,

how do you find your optimism or hope?

Because sometimes it can seem so bleak.

And I understand that people have to face a reality of it as well, but also to have that ammunition of thinking, right, what do we need to do now?

Well,

it's sort of what's in awful, actually.

And what's in awful is that the evidence is becoming more and more difficult to ignore.

I mean,

if you look in terms of evolution at David Attenborough's commentaries on the programmes he makes from the first Blue Planet where he said, and it's all under terrible pressure.

And Blue Planet 2, he went, you're doing this.

And the new series, he's like, seriously, pack it in.

I mean,

he's really gone for it on Seven Kingdoms.

And there seems to me to be a little less pushback.

It's no good going, well, we've passed a point and there's no point trying now.

I do think young people get it.

Not the ones who are gluing themselves to the train I want to be on, but the other ones.

In terms of the oceans now,

beyond the reefs, the ecosystems that you know about in the oceans,

if we achieve the climate goals that have been set, so this

still that we're there with this attempt to limit the temperature rise to two degrees or so,

is that

sufficient?

Or as you said, perhaps for the reefs, we're already locked in.

Do you there's a is that that statistic you gave, uh Heather, was was um stunning that perhaps by twenty fifty or frightening by twenty fifty there may be no living coral left or very few areas where the coral is there.

Yeah, I mean I think it will be changed dramatically beyond all recognition and I certainly certain reefs are like that today.

I mean you know any talk to any scientist who's worked on the Great Barrier Reef for any period of time and and certainly working in the Chagos Archipelago, I know that in nineteen ninety it got hammered, 90% of corals dead, and then it bounced back and it was a happy ending.

I've watched it personally this time go through that and see

what was this incredibly rich, perfect coral reef and this amazing ocean wilderness area straight out of Blue Planet turn into

these grey,

you know,

horrible, rocky, broken, you know, like moonscapes.

They look completely different.

And it's heartbreaking, and I don't know if there's going to be a happy ending this time.

They're not all gloomy, though.

No, no.

There is a glimmer of hope from the Waldeves, just north of the Chagos, gone through much the same bleaching events.

So 97, 98, some areas of reef were completely devastated.

And today you can swim over some of those areas and see almost no coral recovery from that die-off.

For one reason or another, some bits haven't come back.

The bones of the corals are strewn across the bottom like some sort of elephant's graveyard.

But if those areas are protected well from other sorts of human pressures like fishing, for instance, then they're able to thrive in a different way.

And I've dived in sites which have got you know, maybe 3% of the bottom is covered in living coral, but they've been protected from fishing.

And you can hardly see any of the bottom for fish.

It's just these huge schools swirling around you.

They're almost like rivers flowing across the seabed.

And

every hole and ledge is filled with fish and turtles and mori eels of all sorts.

So it is possible to see that coral reefs can still be beautiful and wonderful.

They're not going to be the same as they are, but with the right kind of nurturing and protection, we can make them the best that they can be out of a bad deal, really.

And there's a lot of animals and plants on reefs that are not coral that are not impacted by this this warm water temperature in the same way I mean there's there's huge numbers of ways in which warming affects species but you know there are winners and there are losers out of any change and so we really need to you know focus on making the reef as good as it can be and

that way it will support fisheries, it will support people

for

tourism livelihoods, it will still be a wonderful place for people to go on holiday, the water will be even warmer, if anything, than it is today, and the sea level will be a bit higher.

So

those stilt houses set out across the coral reef will be even more beneficial than they are at the moment.

Right, I'm going to stop there.

No, no, no, no, no.

We're on a moment of optimism.

Anyway, so we asked the audience a question and we asked them, what would you most like to find washed up on the shore?

Again, we didn't realise how dark that could be and most of these these won't get read out.

So, what have you got, Brian?

It says

the Tory party.

But then, no, that would spoil the environment.

So, at the end, it gets very dark.

So, we'll leave that one.

What would you most like to find washed up on the shore?

A treasure chest full of Brian's C Ds.

You absolute creeps.

C D?

Yeah.

Imagine these.

Both albums in there in a wonderful treasure chest.

A message in a bottle sharing the secrets of Brian Cox's eternal youth.

What is it this is?

Brian Cox.

We're beginning to get a pattern here, aren't we?

This one's quite surreal.

Lasagna.

From Ben Garfield.

I've got the Loch Ness monster, Bracketts, who now lives in the Atlantic Ocean because climate change.

Well,

so thank you very much to Callum Roberts, Heather Coldaway and Marcus Brigstock.

Next week, our producer has booked Ed Byrne, and because she booked Ed Byrne, she went, because we booked Ed Byrne, we're going to do fire.

What worries me is the week after she's booked William Shatner so I have no idea what that's gonna be

goodbye

thanks very much for listening uh we hope you enjoyed the podcast we hope you understood it they will have enjoyed it Well, they might not have done.

There might have been a point where you said something that was confounding or one of our guests said something which made them go, this is much harder than I thought.

So, why would they have listened all the way to the end if they didn't enjoy it?

Just to impress their friends, all right.

Well, anyway, if you did enjoy it, then there are lots of other Infinite Monkage podcasts you can download on BBC Sounds.

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