When you dive through the waves, you enter another world, our ocean.
This giant pool of liquid water covers 70% of the Earth's surface
and on average, it's 4km deep.
And down here, the rules are different.
You can move freely in any direction.
You can live an entire lifetime and you never see the sun.
And at night, jellyfish like this rise up through this alien world
to hunt near the surface at night.
And as the Earth turns, the jellyfish go back down
and this dark water is lit by our star
to form the blue of our Blue Planet.
In this lecture, we're going to be looking at
that ocean engine and its impact on our lives and our climate.
The jellyfish are just the tiniest hints of the beautiful complexity
that's hidden down there.
APPLAUSE
Hello and welcome to the Royal Institution Christmas Lectures,
and a special welcome to the virtual audience who are joining us
from homes and schools across the UK and Ireland.
I'm Dr Helen Czerski
and I'm an ocean physicist from University College London.
And this is Planet Earth.
And we don't often see this view of it, we're looking down
at the Pacific and this gigantic ocean covers an entire third
of the Earth's surface.
We often talk about Earth as a Blue Planet, but this is why -
there's so much of it.
There was a famous science fiction writer called Arthur C Clarke,
who once said, "How inappropriate to call this planet Earth
"when it's so clearly ocean."
And I tend to agree with him.
So here are the familiar continents, the ones we live on,
and we can now see that they're just part of this ocean world.
We learned in Chris' lecture that it's the workings of the Earth's
system that determine the climate and the habitability
of our home planet.
And what we'll learn is that the ocean is at the heart
of that life support system.
We're all living in the oceans' shadow, whether we know it or not.
And I am an unashamed ocean enthusiast.
I think it's the most amazing feature of our planet.
And I'm hoping that today I'm going to convince you all
to join the ocean fan club.
And the ocean may seem sometimes like an alien world,
but it is essential for everything we take for granted.
So we have so much to explore.
We've got the world's largest waterfall,
the version of a rainforest that you get in the ocean,
what the bubbles are really up to
and quite a lot of poo because it's very important.
But first of all, we want to know something about where we're going.
And we knew very little about the oceans, really,
until this ship came along, the HMS Challenger.
And in the 1870s, this ship went on an enormous
four-year voyage around the oceans.
They covered 79,000 miles.
They studied everything they could find about the ocean.
And this, this was the birth of oceanography.
So just imagine setting out on that expedition.
What do you know about where you're going?
Well, not very much and if we look at the map here,
this is kind of a representation of the knowledge of the ocean.
So we know where the coasts are.
So we can see there's North America and South America,
there's Africa over here, we can see Australia.
So we know what shape the edges of the ocean are.
But everything in the middle, that's just hidden,
it's unknown knowledge.
Well, Challenger started to map the anatomy of the ocean
with a very simple measure, it measured temperature.
Erm... It's just one of the measurements that they made.
And the thing about a ship is, it can only go to one place
and it can collect data in that one place.
So let's uncover some of the ocean knowledge here.
And what we're looking for is temperatures,
let's peg a sample here.
So we've uncovered, we've got a water sample,
we've uncovered a part of the ocean and we can see underneath
that this is red, so this is telling us that the ocean here
is really warm, it's about 30 degrees.
So let's take our ship somewhere else.
We can take another sample over here, perhaps?
And this one, this one's purply blue.
So we've uncovered a bit of ocean knowledge that the water here
is perhaps minus two, nearly minus two, so it's really cold.
And perhaps one more over here.
So you can see... That's what's going on here.
So we've got green underneath here, so our water sample here
is 15 degrees.
But you can see that this is a really slow way
of mapping the ocean.
So for 100 years after Challenger,
ships went out in the ocean, but when they measured
surface temperature, basically they were colouring in
this map of ocean temperature, one tiny dot at a time.
You need a lot of patience to do that, but it is all we had.
And the problem with ships is, they're big and expensive
and they have to come home sometimes.
So if we really want to find out, we want to find this knowledge,
the temperature knowledge of the ocean,
how about sending something that doesn't need to come home?
Well, this is an Argo float, this is one of the things
that can do that and these are buoys that can float
around the ocean and at the moment, right now,
there are 4,000 of them, nearly 4,000, floating around the ocean.
We can see them here.
So each one of these little dots is a track of one of these drifters.
And what they do is they go down in the ocean
to one kilometre's depth.
They just drift wherever the ocean takes them and then they go down
to 2km and then all the way back up to the surface
and they're measuring along the way.
And the antenna on the top here then sends that data home
and then the drifter, the Argo float, goes back down and carries on
wherever the ocean can take it.
So these are telling us not just about the surface, but also
about the interior of the ocean.
But it's still not really colouring in on map of the surface
ocean really quickly.
We can still only measure in a few small points.
So our knowledge of the temperature of the ocean didn't really change
until satellite technology and computing power came along.
So we're going to uncover the map of surface temperature
with this thing here.
So what we want is a countdown from everyone,
to uncover this temperature map.
So here we go.
ALL: Three, two, one.
OK, so now we can see what Challenger couldn't,
we can see how much detail there is down here.
And the colours here represent temperatures, so we can see
the warmest water is this red along the equator.
That's probably what we expect - nice warm water at the equator.
And then closer to the poles, we've got bluey-purple on the map,
so that means water that's much closer to the freezing point.
But then look at all the detail in between.
So, for example, here we can see the Gulf Stream coming up the coast
of America, this warm water stretching up the coast here.
And then if we look a bit further down now,
once we really get to zoom in on the detail,
we start to see patterns that we don't expect.
Down here, for example, we can see on either coast of Africa
at the same latitude, there's cold water on this side
and warm water on that side.
And then when we really look at all these details,
there's all these beautiful swirls,
this is a work of art written in temperature.
There's an astonishing amount going on.
What this is telling us is that all that water in the ocean
that looks the same isn't the same.
It has anatomy, it has structure.
And we're starting to see with this temperature map
what that structure looks like.
So, it's time to dive down into the ocean.
And for all I love the ocean,
I really hate cold water,
so I'm going to pick somewhere nice and warm, up here.
So, in the Gulf of Mexico here, it's lovely and warm.
It's got surface temperature of about 28 degrees C,
so that - nicely tropical, that's what we want.
So, that's where I'm going to go exploring.
So, let's imagine sinking down into the ocean at that spot.
We're leaving the waves behind and it's becoming murky and gloomy
as the sunlight disappears.
And quite soon it's just dark.
And there's occasional spots of bioluminescence.
And we're sinking down through the ocean,
two kilometres to reach the sea floor
and then we land on the bottom.
So, what lives down here?
Well, in 2013, one of these was discovered
at the bottom of the Gulf of Mexico,
and it's a really strange creature - it's a shark.
They grow to about six metres long.
They live to around 400 years.
But the strangest thing of all about finding this shark here
in the Gulf of Mexico is that this is a Greenland shark.
It's a highly cold-adapted species
that normally lives in the Arctic Ocean.
So, what's an Arctic shark doing in the tropics?
That's a good question.
To answer that, we need to have a think about salt.
So, if there's one thing that we know about the ocean -
most people know about the ocean - it's that the ocean is salty.
Oceanographers call that salinity.
So, saltiness and salinity are the same thing.
But it's often easy to forget that the ocean is salty
because all that salt is invisible.
Gemma here's got a bottle that's got water
that's as salty as the ocean.
And you're going to let it go.
Go on.
And what we can see is that as the drops hit this hotplate
the water is evaporating away immediately,
and we can see it's leaving behind salts
in these beautiful patterns here.
And the thing is that these are only tiny drops
and they still contain enough salt for us to see.
So, when it comes back to the whole ocean,
how much salt is there down there and what's it doing there?
Well, I've got a guest who's going to help explain this.
SHE LAUGHS
What an entrance!
Chris, hello.
Why have you come to visit us in your bath?
Well, as you well know,
the Christmas Lectures are quite hard work,
so I thought I'd have a relaxing, freshwater bath,
but I heard a saltwater bath might be even better for me.
So, you have come to get some salt for your bath?
If that is possible, thank you, yes.
Are you sure you want this bath to be as salty as the ocean?
I would love it to be as salty as possible.
I think it'll have my skin, yeah. Right.
How much salt do you think you need?
I think we need quite a lot. Quite a lot. Yeah.
Quite a lot, to cover me up at least.
OK, well, let's start with this.
This is... THEY LAUGH
We've got... It's actually really cold, by the way!
Welcome to oceanography.
It's often cold and miserable.
OK, so we're adding salt here. Is this enough?
Do you really want this to be as salty as the ocean?
I need it to be salty as possible, yeah. I love the sea.
Are you committed to this? I'm fully committed.
OK, right.
So, that's 8kg of salt.
That's how much salt you need to make your bath
as salty as the ocean.
Thank you, Helen!
Right, why is there all this salt in the ocean?
So, rocks, like my pet rock here, contain salt -
the ones that are exposed at the Earth's surface -
so when the rivers run over those rocks,
they dissolve the salt and deliver it to your oceans.
So, it's all to do with the rocks.
Of course it's all to do with the rocks! Yeah, yeah, yeah.
This is the ocean lecture!
OK, off you go. Enjoy your bath. Bye-bye. Thank you very much.
APPLAUSE
The anatomy of the ocean is written in salt and temperature,
and now we know about those, we can start to see why they matter.
And one of the things they do
is to create the largest waterfall in the world.
So, let's come over to the map over here.
We're going to go to a very specific place on the globe.
We're going to look up here.
Let's come back, and here we can see Greenland.
This is the North Atlantic and we've got Iceland here.
So, this region is where we're going to be looking.
But I want to show you what it really looks like underwater,
because even in a really big storm,
the surface of the ocean is really quite flat.
But, if we look underneath the surface,
it doesn't look like that at all.
I've got this fabulous sandbox here.
Now just to orient you, so we looked at that area on the map,
and in the sandbox Greenland is on this side,
so the North Atlantic is stretching down that way away from me.
Iceland is over here and I'm standing in the Arctic right now.
So, this is all sea floor.
This is a really deep basin down here,
it's about two kilometres deep.
So, I'm going to walk around the other side
and start digging because on this side we've got the Atlantic,
so this is going to be quite a lot of digging.
So, the ocean here is really deep.
It's going to go down to about three or four kilometres
beneath the sea floor.
So, it's taking a bit of work here.
Greenland's getting a bit bigger in the process.
Iceland's over there.
OK, so we're starting to see the shape here now.
So, we've got - this is the North Atlantic.
So, what we can see now is, first of all,
that the sea floor has shape.
There's all this stuff going on,
even though we can't see it from the surface.
There are mountains and valleys and vast plains underwater
and they are enormous.
This is what we can see here, these two massive basins.
And there's a ridge in between
stretching from Greenland to Iceland.
So, we're going to look at a line, a cross section,
that goes through this bit here.
And we've got a model of it over here.
So, here's our cross section.
We've got the Arctic on this side
and this is the south where the Atlantic is.
So, the first thing is that we can see that all of this water in here,
it all looks the same, right? It's just water.
Well, I'm going to add a little bit of red food dye to it.
Just in the top here.
So what we can see
is that this red food dye is staying at the surface
and there's a reason that it's staying at the surface
because there are actually two layers of water in here.
It's just that we couldn't see them before.
If we look at this from the side,
what we can see is that there's this warm layer,
a layer of warm water in here.
And the red dye has just showed you where it is.
But underneath the water is a little bit cooler.
And the thing that the temperature is doing is
it's changing the buoyancy of the water,
so that red warm water stays at the top.
It doesn't mix with the water underneath.
And that's why the ocean has structure,
because it doesn't all just mix up.
So, now, Helen here's going to release this cold water here.
So, this is Arctic water that's really cold.
And we're going to have a look at what it does.
And there it goes, cascading down to the bottom.
So, this is cold, dense water
and it's flowing over the ridge
and it's filling up the basin over here.
So, let's have a look at what this means back on our model here.
Here we are. This is the Greenland Sea up here.
This is the cold Arctic water,
and cold water from the Arctic is flowing over this ridge
down into the North Atlantic,
and it's filling up the deep ocean from underneath.
And this is the largest waterfall in the world.
It's 3.5 kilometres high.
The amount of water going over it
is 200 times bigger than the largest waterfall on land.
So, that's 5 million cubic metres every second,
is pouring over this.
And the thing I love about this is that sailors have been crossing
from Iceland to Greenland for centuries and they've never known
that this enormous waterfall was just underneath them.
But it's not just happening here.
Cold polar water is filling up the deep ocean basins
all around the world.
So, this is the reason that the deep ocean is actually really cold.
So, now we can get back to the question
of that Greenland shark.
What was it doing in the Gulf of Mexico?
And the reason it was there is that the Gulf of Mexico,
really deep down, is filled up by cold water from the poles
that stays at the bottom.
Where it was discovered, it was only four degrees Celsius,
even though at the surface it was 28 degrees C.
So, we've got these two major layers in the ocean.
We've got the warmer layer on top,
which is all of that beautiful surface map that we saw before.
But most of the deep ocean basins are filled up with cold water
that came originally from the poles.
That's a really important thing about the structure of the ocean.
Now, I love maps, but they do annoy me in one respect,
which is that they show the land as being stationary -
which it is - that's all fine.
But they also show the ocean as being still, and it really isn't.
It's moving.
If you remember those beautiful swirls on the temperature patterns
at the start, it looks like they're moving.
There's lots of energy there.
So, we're used to the idea of atmospheric weather.
That's what happens when we go outside
and we get rained on or whatever.
What about the idea of ocean weather?
So, to talk to us about ocean weather,
please welcome Dr Eleanor Frajka-Williams. Hello.
Hello.
So, first of all, you can't join us in person,
but you've got a very good excuse for that. Tell us why that is.
That's right. I'm isolating before heading to sea next week.
So, where will you be going? We'll be going to the Atlantic
between the Bahamas and Canary Islands
to measure how the ocean circulation is changing.
Well, ocean circulation is very topical here.
So, we've got a demonstration here.
So, we have to remember that the Earth is a rotating planet
and the ocean is just liquid sitting on top of a rotating planet.
So, we've had water that's been rotating,
and I'm going to put dye in.
Eleanor, as I put the dye in perhaps you can tell us what you see.
Yeah. So, as you put in the dye,
you can start to see how the ocean is moving
and what you'll start to notice is that it generates swirls
and filaments of dye, rather than just a giant cloud of colour.
They spin up into what we see in the real ocean and call eddies.
So, the swirls we can see here are caused by the Coriolis effect.
On a spinning planet, whenever you have a current,
you get these beautiful swirls formed.
I think we've got some eddies over here.
So, if we have a look, and I think Eleanor can see this as well.
So, we've got a map here that shows surface currents.
So, Eleanor, we can see these eddies.
Tell us what we can see here.
Off the tip of South Africa, there, you can see these ocean currents
as the really highlighted strong rings or doughnut shapes, really,
of the currents.
These are several hundred kilometres across in the real ocean,
and they're carrying warm and salty water from the Indian Ocean
over long distances and into the Atlantic.
And these aren't just... So, we can see some really obvious ones here,
but these - these are all over the ocean, aren't they?
That's right, that's right.
So, these are some of the largest, most spectacular ones down there,
but really, these eddies are everywhere.
And why do you study these things?
Why are oceanographers interested in these eddies?
So, eddies carry heat and properties around the ocean.
They also contain a massive amount of kinetic energy -
something like 80% of the total kinetic energy of the oceans.
So, these are these enormous features.
And there's a connection between this ocean weather
and the climate, isn't there? Tell us a little bit about that.
Absolutely. So, what we're starting to find out now
is that where these eddies deposit their energy,
where they eventually dissipate and so you can no longer see them,
has an influence on shaping the large-scale ocean circulation.
So, the currents that are moving and influence...
Influencing how the ocean influences climate.
Brilliant. Thank you very much.
Well, good luck on your research expedition,
because I'm sure that's going to be really exciting.
And thank you for joining us. Thank you.
APPLAUSE
So, there is ocean weather.
It's slow - slower than our atmosphere -
but it's making these amazing patterns all the time.
So, the patterns are all very pretty, but do they matter?
You know, it's always nice when things are pretty.
Well, to see why they matter, we've got a demonstration here,
and the important part of this demonstration...
Oops! THEY LAUGH
Thank you, Fran.
..is the cannonball here.
So, I'm just... It looks just like a normal cannonball.
I'm just going to flick some water at it
and you can see the water... Woo! ..is evaporating off it.
And that's because this cannonball is really, really hot.
It's around 350 degrees Celsius.
So, it's definitely not something you should touch.
And it's carrying a lot of energy, about 300 kilojoules.
So, what Fran is going to do, while I stand back...
..is she's going to put the cannonball in the water
and I'm going to follow along with this thermal camera.
We can see on the thermal camera the cannonball is super-warm
and here we go into the cool water.
LOUD HISS
That is a lot of hissing!
So, we basically just dumped all of that energy into the water here.
Now I'm going to do something that looks like a terrible idea,
which is put my hand into the water
and it's not actually that hot.
What I'm going to do is mix it up, and you can see with the camera
there's cooler water coming through from underneath.
But actually, considering the cannonball was at 350 degrees C,
what we could see with the camera is that the water over here is only
around 40 degrees C, so we dumped all of that energy into the water
and the water's only heated up by about 15 degrees -
really not very much at all.
And what that demonstrates is something that we call
the heat capacity of water,
and this is really important - that it takes an enormous
amount of energy to heat water up by even a tiny bit.
And this is why something like boiling your kettle
is such an energy-intensive thing,
because you have to just keep pouring energy in.
But the critical thing here is that even though the water hasn't
heated up by very much, the energy is still in there.
This water is now a store of heat energy,
and that matters when it comes to the ocean,
because the ocean can also store energy.
So, let's have a look to see why that matters for Earth.
Let's have a look at a planet which doesn't have an ocean.
Let's have a look at Mars.
We know it as the Red Planet and it's got very little water,
no known liquid water.
And the thing about Mars is that there are these
enormous temperature variations.
As the planet rotates around and parts of it go from day to night
and back again, the daily variation in temperature
can be 100 degrees centigrade - it's enormous.
Just imagine how uncomfortable
living on a planet like that would be.
So, let's come back to the Earth
and have a look at why that doesn't happen on Earth.
So, the way that things work on Earth is that energy flows
through the Earth's system.
It comes in as sunlight, it hangs around in the Earth a bit,
and eventually it's lost to space.
So, what happens is that the ocean, when sunlight hits it, warms up,
so it stores energy.
It's acting like the battery of Earth.
It's recharged with energy whenever there's loads of sunlight,
and then on the cooler days,
it can release that energy back into the Earth's system.
So, it's basically the storehouse of energy on Earth.
And that means that you don't get these extremes of temperature
on Earth in the same way that you do on Mars, because when it cools down
a little bit, the ocean gives you some energy back
and then it recharges itself when the Sun comes out again.
And so the temperature on Earth doesn't vary very much.
The other thing about those patterns that we saw
is that they're showing us not just that the ocean is storing energy,
but the temperature is telling us where it's stored,
and overall, the ocean is moving energy from the Equator
towards the poles.
It's spreading it out, sharing it out, around the planet.
So, when we asked the question about why we've got such a nice,
stable planet to live on, why it's so easy to live here -
it's because we've got an ocean.
It really matters that we've got an ocean.
So, we've had a quick tour through the physical nature
of the ocean, and it's varied and dynamic.
It's got all these beautiful patterns
and it carries vast amounts of energy.
But there are more things in the ocean than heat.
So, virtual audience, what are your ideas for what other things
you might find in the ocean?
Shout things out.
Oh, yes, just shout.
ALL SHOUT AT ONCE
Fish! Sealife!
SHOUTING CONTINUES
Coral reefs!
Seahorses, yes.
OK, so we have lots of ideas there.
Seahorses and turtles and fish
and the thing that they've all got in common
is that they are all alive.
Our ocean - this physical engine - is full of life
and we can see a little bit of that here.
So, what we've got here is a tiny drop of ocean water
from Gylly Beach in Cornwall here.
And we've got a green laser that's shining through the droplet
and it's projecting the insides of the droplet onto the screen here.
And we can see that there are these little things moving around
inside - tiny, tiny things - and we could never see them
inside that droplet with our own eyes.
But the laser is showing us there is something there.
There is life in this ocean water.
So, the ocean isn't empty.
It does have living things in it.
But to see the little ones, you need to know how to look.
And so I have a guest who can help,
so please welcome Professor Bridget Wade.
APPLAUSE
Thank you for joining us, Bridget.
Now, we're going to talk about something called phytoplankton.
Tell us what those are.
Yes, so, phytoplankton are these microscopic, single-celled organisms
and they photosynthesise in the oceans.
And we're used to thinking of these larger organisms like whales
and turtles and things,
but phytoplankton actually make up about 90% of the ocean's biomass.
So, they're really tiny and they're harvesting sunlight.
Yes. So, they're photosynthesising and therefore taking in oxygen
and actually in the air that we breathe,
about 50% of the oxygen comes from phytoplankton.
So, we really need them there, in the oceans. Yes, exactly.
You've got some examples here. Mm-hm. Let's have a look.
Yes. So, here I have the coccosphere.
It makes these plates out of calcium carbonate,
and the White Cliffs of Dover that people will be familiar with
are made out of these.
And it's really intricate.
It's just a single cell and it's so delicate. Yeah.
And there's millions of species, and they're all very different
and diverse and beautiful.
And you've got another there one as well. Yes.
This is a diatom and these are made of silica.
And just like all the other types of phytoplankton, they're living
in the surface waters of the ocean and photosynthesising.
And how big... Because, you know, I've never walked out onto a beach
and seen one of those, so how big are they?
So, they're very small.
Everything's less than half a millimetre in size.
So, less than the size of a grain of sand.
This would be about 100 microns
and this one would be about ten microns.
And there's a thousand microns in a millimetre.
So, let's play an imagination game here.
Audience, we're going to imagine that we're shrinking ourselves down
so that the entire lecture theatre is the size of that drop.
And we're going to populate that with some phytoplankton.
But that's quite a lot of phytoplankton,
so we needed some help.
And Hornsey School for Girls helped us out by making models.
So, here we are.
So, Bridget, can you recognise anything they're making here?
Oh, yes. Looks like a lot of work! Some of them are amazing.
And they're all single-celled organisms, but they're beautiful.
They all make these amazing shells
and they're really diverse and ornate.
I like the amount of creativity going on here.
It's like everything in the craft box is being used.
All of that detail, and yet the phytoplankton
just make it for themselves.
We've got some of the examples here, and these are to scale.
Imagine that drop was the size of the lecture theatre
and these are the right size.
So, what have we got here, Bridget? What can we see?
So, these are some of the coccolithophores
that are made out of calcium carbonate.
We also have a diatom here.
They're very important photosynthesisers.
They make about 25% of our oxygen.
And then we've got descending on us here!
THEY LAUGH What are these ones?
So, these are dinoflagellates, and they kind of look like spaceships
and Christmas decorations, and they're very ornate
and they have these amazing flagella.
So, these are the things that are hanging off the bottom here? Yes.
And are they using them? What do they do?
Do they swim with them? What do they do with those? Yes.
They can use them to sort of move through the water.
But these are really... They're plankton - they're floating.
They're not really swimmers. They're just drifting. Yes.
Do these features have functions?
Why do they need to look so different?
Yeah. So, just like plants, they need nutrients from the ocean
and they need oxygen and sunlight,
and so trying to increase their surface area,
and they also might be trying to prevent predation.
Everything feeds on these, so they're the base of the food chain.
So, all marine life is dependent on the phytoplankton.
You have this invisible forest of unicellular or single-celled
organisms, and they're really important.
I mean, some of the ones here, these are cyanobacteria.
So, they're bacteria and they photosynthesise
and they're actually the most abundant photosynthetic
organisms on Earth.
So, they're all just hidden in the oceans
and different ones are found in different places as well. Yes.
And they're all so stunning and beautiful.
And they're living in the surface waters -
they want to be in the sunlight.
But you find them everywhere from the Arctic
to the tropical regions. And they're keeping everything...
I love the idea that you could swim through a forest of the ocean
and never know it was there... Yes. ..because it's so tiny.
And I feel so lucky that I get to see these.
This microscopic world! You get to admire their beauty.
Brilliant. Thank you very much, Bridget. Thank you.
APPLAUSE
So, phytoplankton are great sun harvesters, they're great at taking
the energy from sunlight and using it to build sugars
and to build themselves, but if you can't harvest sunlight
for yourself, then a phytoplankton looks a lot like lunch.
And it's time to meet the zooplankton - they're tiny creatures
that also drift on the ocean currents.
And some of them are big enough to see,
like the jellyfish we saw at the start.
But lots of them are really tiny little animals.
But if you walk out, if you go to the beach one day,
you look in... you're wading in the ocean,
you often won't see zooplankton.
You can see lots of other things,
but there aren't any little tiny animals to look at.
So where are they?
If there are all these zooplankton, where are they living?
Well, last year I did a really special scuba dive.
I was out near Hawaii, so I was in the middle of the Pacific Ocean
and we got into the water just as it got dark.
So we were floating in the boat a couple of kilometres offshore.
The ocean floor was two kilometres beneath us,
so it was really, really deep and the water was deep navy blue.
And so we got over the side of the boat and we floated
and the sun went down.
And the ocean went black.
We floated in the middle of the Pacific and then all of this
rose into the water around us and it was astonishing.
So what we can see here are just so many little creatures.
We can see their sort of jelly-like bodies.
Some of them are single by themselves.
Some of them are attached together.
This one was making little streaks of light.
So some of them were bioluminescing
and some of them are big enough
to see on this image here.
But there were loads and loads that were even smaller than that,
and we were just surrounded by them.
I could have spent hours watching all of this.
So where had they been?
Well, they'd been hiding down in the depths.
So, zooplankton like this feed on phytoplankton.
The phytoplankton need to be up near the sunlight, but the zooplankton
don't want to be eaten by fish.
So they hide deep down in the depths.
And when it gets dark, they rise up towards the surface.
So, like this, where they can hunt at night and they can hunt
without being seen.
And then when the sun comes up the next morning,
they sink down back into the depths.
It's the biggest migration on Earth.
It's an astonishing phenomenon.
But life in the ocean isn't easy and to show you
some of the challenges we've enlisted the help
of the Lilian Baylis Technology School to play a game.
So here's the game. We need to explain the set-up to start with,
so we've got three zones.
So, in the middle here, we've got the ocean.
That's the bit in between those two lines.
Down here, this is the bottom of the sea.
And then up above the ocean up here where the sunshine is,
that's the atmosphere,
so that's outside the ocean.
And then we've got different types of players.
So we start off with the players in blue.
So the ones with the blue hats,
these ones are the zooplankton.
And it's their job
to scoot around the ocean.
They're these tiny animals and it's their job
to collect nutrients.
So nutrient balls like this one,
because that's what you need
to build life out of.
So we've got some nutrients, but the zooplankton have another job,
which is to avoid the fish.
And if they get caught by a fish,
then they and any nutrients
that they're carrying sink to the bottom of the ocean
and they can't carry on with the game.
So let's start off with a countdown.
So are you ready for a countdown from three?
Ready.
ALL: Three, two, one, go!
So we can see... here go the zooplankton,
they're collecting the green at the top.
Fish are going round collecting zooplankton.
And you can see that when the fish have touched the zooplankton,
the zooplankton sink down here and they carry nutrients
down into the depths with them.
But after a while, it starts to look quite boring, doesn't it?
Because what's happened is that all the nutrients
are down here at the bottom and there's nothing left in the ocean.
There's no nutrients near the sunlight, so nothing can grow.
So this doesn't work very well,
but we can try the game again
with another player.
So our new player is dressed in red here.
She's got a cape and a hat and she has a very special role.
What she can do is she can go down to the bottom of the ocean
and she can collect nutrients
and she can bring them up to the surface.
So let's play the game again. Off they go.
So here go the zooplankton.
They're collecting up the nutrients.
The fish are touching the zooplankton.
So we're getting nutrients to the bottom here.
But then our red player can come along.
She's collecting up the nutrients, so they go back to the top
of the ocean and then the zooplankton can go again
so the life can carry on.
So here we go.
More nutrients being collected down here.
And she's going to take them all the way round and put them back
at the top of the ocean.
We can see that once you've got this extra player that does this job,
then the game of life can just go on and on.
So the question is, who was this player?
So virtual audience here, would you like to guess who that player was?
What's in the ocean that might do that job?
Let's shout out some guesses.
ALL SHOUT AT ONCE Some type of plankton?
Plankton?
Different fish?
Different fish might do that job.
There's lots of ideas here.
Well, let's have a look.
So what our caped crusader really was -
her job is that she was a whale and what she was doing was eating
at the bottom and then coming up to the top
and then she was pooing.
And this turns out to be really important.
So I've got a picture of some whale poo up here.
And it's...it's a bit icky, isn't it?
It's red. It's floating in the ocean there.
And turns out it's really hard to get a sample of real whale poo
because whales are quite shy about this kind of thing
and it's quite hard to collect it.
So I can't show you real whale poo.
What I can show you is a model to talk about what it does.
So here's the model
and let's put the poo in the ocean.
It's... Eugh!
It's horrid!
So we can see that as soon as it's in the ocean,
it starts releasing things.
And the reason that the whale poo is red
is because it's full of iron
and that's a really important nutrient.
And they also have other things
in them, like nitrogen.
And so basically whale poo
like this, little pieces of poo,
or sometimes it's a bit more liquid.
It's all really icky.
And they are incredibly concentrated doses of ocean fertiliser.
And because whales do deal with
all their bodily functions,
apart from feeding at the surface,
what they do is they eat things
like krill down in the depths
and then they come up to the surface
and they release their poo
and just look, they're releasing
these nutrients everywhere.
They're fertilising the surface ocean.
So the lesson is that life in the ocean has a problem.
The sunlight is at the top
and, over time, the nutrients tend to sink downwards.
But life can solve that problem.
Something is doing this very special job of bringing the nutrients
back up to the surface
so the game of life can carry on.
It doesn't have to be a whale.
So what is there that can break this barrier, that can bring
the nutrients from the depths up to the sunlight?
Well, it turns out that on a rotating planet,
Earth itself actually helps us.
And whenever we have a current on a rotating planet,
there's something counterintuitive which happens,
which is that the currents
can't go in a straight line.
They have to curve.
The nutrients are pulled upwards to the surface.
So what's actually happened is that
the surface is being pulled away and
it's leaving a gap in the middle.
And so the water from underneath,
with all those nutrients,
can rise up through that gap.
And this is called upwelling
and it's really important
in the ocean.
This doesn't happen everywhere,
if we have a look at the globe here.
And what we're looking at is a map of chlorophyll.
And this chlorophyll shows us that life is growing.
So it only happens in places where there's both nutrients and light.
And if we look around here,
we can see that there isn't chlorophyll everywhere.
There are patterns,
but there are some places where it's really strong.
So if we look at the side of South America here,
all down here, look at this,
there's loads of chlorophyll down this coast.
And the reason is that this is a big region of upwelling.
There's nutrients coming from the deep ocean
coming to the surface, meeting the sunlight, and it makes
this region a city of the ocean.
There is so much life there.
But if we move the globe round a little bit further,
here we get to the middle of the North Pacific here.
We can see there's a huge region here
where there's almost nothing growing at all.
And that's because there is no upwelling here.
Actually, things tend to go the other way.
And so what we're seeing is the structure of the life -
there are these cities of the ocean along the coasts here
and there are deserts
where the nutrients can't get up to meet the sunlight.
So what we've learned here is that there is constant recycling.
There are only so many atoms on Earth.
Basically, if you want to succeed as life,
what you need is to make yourself from poo
because that's how you recycle the atoms
that were something else before you.
The ocean is a massive recycling system
and we're basically all made from poo
because that's how a healthy ecosystem works.
And now we can start to think about us humans and our relationship
with our ocean.
We look up here, up at the Pacific Ocean,
I could look at this view for hours.
Now, our European maps are dominated by land
cos that's where we live.
We make our maps that show the places where we live.
But in the Pacific here, there are lots of tiny islands.
And the people who live here,
their worldview isn't dominated by land.
It's dominated by the ocean.
I mean, why wouldn't it be?
You've got all this ocean and the people on those islands
have centuries of understanding the ocean, of observing it
and of learning how to navigate across it.
So to share their knowledge and perspective,
I'm really honoured
to be joined by one of the greatest modern Polynesian navigators,
from Hawaii, Nainoa Thompson.
Nainoa, hello.
Could you perhaps start by telling us a little bit about the place
where you live?
I'm in, like, the largest country on the Earth called Polynesia.
It's mostly ocean - it's 600 times more water than land.
And so I come from an ocean world.
Now, most of our audience won't be familiar with the story
of this amazing voyaging canoe - Hokule'a.
Could you give us an overview?
There was an amazing group of dreamers and pioneers,
courageously said, "We're going to bring back our culture.
"We're going to bring back our tie to the oceans
"by building the single most important artefact
"of Polynesian culture, the voyaging canoe."
These are big canoes, sailing great distances.
From the indigenous native perspective,
the navigation integrates everything from the ocean world,
whether it's the heavens, the stars, the sun, the moon, the planets,
to wind, to clouds, to the quality of light at sunrise and sunset,
sea birds, sea life in the oceans, reading the ocean waves.
I mean, if the basis of modern science is observation,
and these are great scientists -
I would like to put them amongst the best.
It feels like we're at a critical point here where we risk losing
something really important if we let our climate
and our oceans suffer any more.
What is your advice?
What do you think we should do about it?
When we industrialised to build better lives for us as humanity,
it worked.
It changed everything.
But what we didn't know was its impact on climate.
And we didn't know its impact on ecology
and we didn't know its impact on culture.
But today we know.
This lecture is focused on 11- to 16-year-olds.
They are the most important generation in human history ever.
They are going to be given the tools to do what we could not do
in the past, the power of technology, their imagination,
their courage, their ability to access information
and make good decisions.
It's about the choices.
Take 500 choices that we make every day, times it by eight billion,
that's four trillion human choices per day.
This next young generation is going to say, "Let's change those choices.
"Let's make them good choices."
That's going to change the world. Thank you very much, Nainoa.
It's been a pleasure to talk to you. Thank you.
So let's have a look at what humans are doing to the ocean
and how that affects our climate.
Now, we've got we've got the Earth system here.
We've got the sun up there.
And the sun is going to deliver energy to the Earth system,
which is down here, so off we go.
So here comes the energy.
It flows into the Earth system, but it doesn't just pile up and pile up.
After a while, it will start flowing out.
Now, on Earth, that means the energy is radiated away into space.
But here, it means that the energy is going to come out of this tube
and it's going to start falling into this bucket.
So we've got energy coming in and we've got energy flowing out.
And as long as the energy flowing in
is the same as the energy flowing out,
then the amount of energy in our system here stays the same.
And we can see how much energy there is
because there's a dial here so we can make a mark there.
So that's how much energy is in our system at the moment.
Now, we learned in the first lecture from Chris that carbon dioxide,
all that extra carbon dioxide we're putting into the atmosphere,
that's a greenhouse gas,
and what it's doing is blocking the flow of energy into space.
It's slowing it down.
So I'm going to do that here by slowing down -
actually, I'll do it at the bottom -
slowing down the flow here
and not spilling all over the floor.
And what we can see
is that the dial...
Can you see it's creeping up?
Because energy is building up.
So we've moved from where we were
all the way around.
We can see energy is accumulating in the system.
And this is what climate change is.
Carbon dioxide is slowing the flow out.
Energy is slowly building up in the Earth system
and it's changing how the Earth energy works.
So we've got a lot of extra energy here.
The question is, where is it going?
And we do know.
93% of the extra energy that we're accumulating
in the Earth system because of climate change,
93% of it ends up in the ocean,
and if it wasn't, the Earth would be far, far warmer than it is now.
So that is a lot of energy and it must come with some consequences.
So remember that the ocean doesn't just store up that energy -
it can also release it back into the Earth system
and that's having major consequences at the poles.
And this is water being added to the ocean from land.
So it was locked up as ice on land.
It melts and it flows into the ocean
and that's causing problems.
It's causing sea level rise.
But that is not the only problem.
Let me show you something else over here.
So I've got to put my glasses on for safety.
So what we've got here...
WHOOSHING
..is a little flask of ocean here,
and I'm just going
to heat it up from underneath
and while that's heating,
we've got a lovely cartoon
in the background here
that shows the ocean.
We've got the beach, we've got some land
and we've got someone's house at the top.
And we can see the blue level here - that represents the sea level.
And you can see that as I heat up the flask, sea level is rising.
So what's happening is that I'm not doing anything to this water
except heating it up and warm water just takes up more space.
So what's happening is it's pushing out of the flask
and it's pushing up and it's creeping up the beach here,
and this also happens in the ocean.
As we add extra heat energy to the ocean,
the warmer water just takes up more space,
and so sea level rise is also...
We know that current sea level rise
is just over three millimetres per year
and about 40 to 50% of that
is just caused by the thermal expansion of sea water.
ALARM BLARES
So as well as all the extra water we're putting into the ocean,
the extra heat is causing additional sea level rise all by itself
because the water we've got is just taking up more space.
But the ocean energy carries on into the Earth system,
it then heats up the atmosphere and the warmer the water is,
the more energy the ocean can deliver to the atmosphere.
THUNDER CRASHES
Some lovely weather here.
So weather's really complicated and it does take really careful science
to understand the influence of individual factors,
but there's a general consensus that warmer sea surface temperatures
will make storms with strong winds
and more intense rainfall occur more often.
So, for example, in 2018, Hurricane Florence made landfall
on the east coast of the US
and scientists estimated, in one of the first studies of this type,
that the rainfall intensity in this storm was higher by 5%,
just because of the effects of climate change.
So, we've followed the energy in the ocean and now
we're going to come to the role of the ocean in carrying stuff,
in carrying atoms that aren't water.
And we've seen that the energy accumulation in our Earth system
is due to carbon dioxide.
We often hear about carbon -
there's carbon budgets
and zero-carbon things.
People talk about carbon-free activities.
So what about the carbon in the ocean?
Well, the oceans are doing as an enormous favour
because they're taking up carbon dioxide.
And since the beginning of the Industrial Revolution,
they've taken up an amount equivalent to all the oil
we have ever burned -
a staggering amount of carbon.
Just in the hour duration of this lecture,
one million tonnes of human generated carbon dioxide
will have been taken up by the ocean.
But how does it get there?
It's all very well to say it goes in, but how does it go in?
Well, this is my area of research.
I study bubbles in the ocean.
So these are packets of air surrounded by water.
And you might think of bubbles as being nice, gentle things
that come along in fizzy drinks or in the bath.
But let me show you the bubbles that I study.
So this is footage that was taken from the back of a ship
in the middle of the North Atlantic.
The average height of the waves here is ten metres.
This was a big storm.
And this is a view that has been seen by seafarers for centuries.
But they couldn't see the bit that I'm interested in,
which is just the top few metres just underneath the surface.
So let's take a calmer example here.
We're looking up at the sea surface
and we're about to see a little wave break over the top
so we can see what's happening underneath.
So it's going to come in from the right. Here we go.
There's the breaker.
And you can see we've got this plume of bubbles formed
just underneath the surface.
And some of them go straight back up to the surface
and other ones stay down, hang around in the water column.
And these are really important
because they're helping the ocean breathe.
That's why we go out in these fairly vile conditions, really,
these big storms, to find out how many bubbles there are,
where they go and what they're doing.
And the reason for doing this is to study the ocean breathing
and find out whether that's going to change in the future.
So what difference would the bubbles make to the breathing?
Well, we've got a demonstration over here to show you.
So we've got some sea water that's been coloured down the bottom here
and Fran's going to pour in some carbon dioxide.
And what we're going to see is that...
So carbon dioxide is an invisible gas,
but what we'll see is that as it fills up,
it's already put that one out,
it's put both candles out,
so we're going to fill up
the headspace here
with carbon dioxide.
And we've got some dye in the water
down here that's going to track
where the carbon dioxide is going.
So now we've dealt with the gas,
we're going to start the breaking wave.
So we've got a little tipping bucket here
that's going to make little plumes of bubbles
in the tank, just like the breaking waves in the ocean.
So we get loads of bubbles, we get a lot of turbulence.
What you can see is that the water is changing colour
and the reason it's changing colour
is that it's taking up the carbon dioxide in the headspace.
It would have dissolved.
It might dissolved very slowly otherwise,
but when you've got the bubbles and you've got turbulence,
all those little packets of the atmosphere
pushed down into the ocean,
they are transferring the carbon dioxide much more quickly,
so the breaking waves and bubbles,
and big storms like the one you saw at the start,
basically are speeding up
the process of ocean breathing.
They're speeding up carbon dioxide being taken into the ocean.
And this is what's happening in a big storm.
So my work is to look at this kind of thing and predict
how it's going to change in the future.
But what I didn't tell you is what the dye in the water here is.
You can see it changed colour, but the reason it changed colour
is that what it actually is, it's an indicator.
It's telling the pH of the water - how acid or alkaline it is.
And the water here started off at about the same pH
as the ocean in 1800, so around 8.2.
And you can see, as we added carbon dioxide,
what happened is we change the pH,
we made it less alkaline and more acidic.
And although this is an extreme example,
that process is also happening in the ocean.
As the ocean takes up all this extra carbon dioxide,
this is ocean acidification.
It's making the ocean less alkaline, so we've changed...
The extra carbon dioxide has already changed the pH -
how acid and alkaline the ocean is,
it's changed that across the whole of the surface ocean,
and that really matters for life.
So we saw... I've got some samples back here.
We saw with the phytoplankton at the start
that lots of them have shells made of calcium.
And for them to build those shells, they need an alkaline environment.
And when you add more carbon dioxide, it takes more energy
to build those shells.
So these shells like this are made out of calcium carbonate.
And we know, for example, that corals are really sensitive
to ocean acidification
and barnacles and mussels also don't do very well in ocean water
that's got more carbon dioxide dissolved in it
and it affects the chemistry of other processes.
So, overall, it's a complex story,
but what we do know is that when we change the pH like this,
firstly, we're doing it too quickly for evolution to catch up.
The animals and other organisms haven't got time
to evolve, to adapt,
so there are new winners and new losers.
And overall, it seems that the future ocean, the ecosystems,
are going to look different
because there's going to be less biodiversity,
just because of this ocean acidification.
So although it sounds great that the ocean is taking up this carbon,
it's taking it away from the atmosphere,
potentially, it has really serious consequences for ocean ecosystems,
which is all... It's a bit gloomy. It's a bit sad.
So it is time to get back to the subject of poo
to cheer everyone up.
And we've seen that carbon can cross the ocean surface
in big ocean storms.
Where does it go next?
So to answer that question, please welcome Dr Stephanie Henson.
APPLAUSE
Hello. Hello.
So tell us, first of all, what parts of the oceans you study.
So I work on the twilight zone -
that's the part of the ocean where no light penetrates.
It's down to about a thousand metres depth. And you've got some samples
of what you find there. What have you got to show us?
So what I've got here is actually some plankton poo.
So this has been produced by a zooplankton -
those little critters that you met earlier.
OK, here we go poo hunting -
keep your fingers crossed, everybody, that we find some.
Oh, we've got a piece there. It's tricky. Here we go.
Get it into focus. So it's this orange thing
with all this fluffy stuff. This orange thing.
Exactly. All that fluffy stuff around it. Oh, da-na! There we go.
The picture we had before was
that we've got the phytoplankton which are harvesting the sunlight,
the zooplankton eating the phytoplankton.
So how does this... explain how the cycle carries on.
Yeah. So zooplankton are tiny little animals
and like every animal, once they've eaten, they've got to poo.
And this is an example of what their poos look like.
But the important thing is their poo's full of carbon
and it sinks down deep into the ocean.
So there's carbon cycling in the ocean, that's the big picture here,
isn't it, that carbon is going round around, but some of it via this poo
kind of drops out of the bottom of that system?
Yeah, that's right.
Actually, only about 1% of the poos make it down into the deep ocean.
It doesn't sound like much, but it's super-important
because without the poos, atmospheric carbon dioxide levels
would be about 50% higher than they already are.
So how do you go about collecting this?
Well, one of the ways that we do that
is with what's called a sediment trap, and we have one here.
It's basically a giant funnel, as you can see.
And we put it down near to the bottom of the ocean,
several thousand metres deep.
At the bottom, there's a bunch of bottles.
We open those on rotation for about two to three weeks at a time.
And it's out there for a whole year.
And the ship comes back, it pops to the surface and we pick it up.
Now, here at the Royal Institution,
we are definitely not shy of playing with the toys.
So we do have some marine snow we're going to release from above.
Oh, here it all comes.
So that's quite a lot, isn't it?
Oh, wow. That's quite a lot!
So how does this work in the ocean?
Does it come down in big kind of rainfalls like this?
Well, it's not quite like that.
So it's not a massive snowfall, like we've just had there with confetti.
It's more like a gentle drizzle of marine snow and plankton poo
falling to the bottom.
Only a tiny fraction of the poo that's generated
makes it all the way to the deep ocean.
But this is having really big consequences for climate change,
because if it comes out of the atmosphere into the ocean
and then from the ocean it goes down into the deep ocean,
then it just stays there.
That's why it's so...
Only about, like I say, about 1% makes it down right to the deep,
but once it's there, it's stored there for hundreds, thousands
of years, even millennia, if it makes it to the sediment.
So it's super-important for regulating our climate.
So zooplankton poo like this is not just something...
It's no laughing matter. Yeah, absolutely.
That is brilliant. Thank you very much, Stephanie. Thank you.
APPLAUSE
So we've only just touched on the two big things
that the ocean moves around - heat energy and carbon,
but it's enough to see
why lots of the things that humans do is causing problems.
We know, for example, that the reason plastics
are a problem is they don't fit in with the ocean's recycling system.
Nature doesn't have a way to help them turn into something else,
so those atoms are kind of stuck.
We know that overfishing affects ecosystems, so it shifts the balance
of what's recycling round and what's living where.
And we know that the polar regions, which are a critical part
of the ocean engine, are changing really quickly, and that's affecting
the rest of the engine.
So we have lots of problems to deal with,
but we also have lots of knowledge.
And I am really excited about being a citizen
of an ocean planet.
It's such a fantastic thing to be and there's so much to appreciate.
So when you look out over the ocean,
just imagine what's going on down there - the swirling ocean weather,
the shunting of vast amounts of heat around the globe.
Imagine the zooplankton rising and falling as the planet turns.
And imagine this blue engine shifting the nutrients
that are necessary for life.
We may live up there, but if we want to get life right,
we need to work with what's down here.
We're part of this ocean planet, not separate to it.
In the next lecture,
Tara will take you even further up into the atmosphere
and look at how humans can live sustainably on Planet Earth.
APPLAUSE