All life on Earth began in the oceans.
But now they're changing more quickly
than ever before in human history.
And we are responsible.
In a television first, we're going to attempt an ocean autopsy,
a comprehensive health check of the North Sea from top to bottom.
This is a place where physics and chemistry and life are all woven
together, and it's directly connected to each one of us.
We have to understand our actions here because the clock is ticking.
Whatever's happening in this sea will give us a strong indication
of where our global ocean is heading.
I'm physicist and oceanographer Dr Helen Czerski,
and I'm joining a state-of-the-art research ship.
It's back on board, so it's all right.
We're happy! Now we've just got to see what data's on it.
The experiments we carry out on board will transform our
understanding of what we're doing to these waters.
That was quite a dramatic reaction.
I'm zoologist Dr George McGavin.
I'll be investigating how what we do on land impacts life at sea.
Oh, my goodness!
Absolutely loads of parasites.
Our investigation will tackle some of the biggest and most challenging
issues facing our planet today.
What happens to the eight million tonnes of plastic
we dump into the ocean each year?
99% of this plastic has been, well, lost at sea.
What effect does chemical pollution have on marine life and on us?
I'm just having this image in my head
of somebody tipping 220 tablets an hour into the Thames,
day after day.
Can life in the oceans survive as the planet warms?
So the more methane comes, thus the warmer it gets.
The latest science is also bringing hope.
I'll discover innovative ways to combat rising seas.
These marshes will be able to keep up
with levels of sea level rise.
It just goes to show what you can do when you work with nature,
and not against it.
From land, from sea, even from outer space,
we're performing a definitive health check on our oceans.
To discover how they're faring today
and how to preserve them for the future.
Our investigation begins at the Dutch harbour of Texel.
I'm about to set sail on a pioneering journey
aboard the Pelagia, one of the best-equipped science laboratories
at work on the sea.
So this is my home for the next two weeks,
and, if you want to study the ocean, you really need access to this
kind of cutting edge facility to get into it.
And I am so excited about going back to sea. Can't wait.
I'm sailing with a multinational team of oceanographers
and marine biologists.
We'll work, sleep and breathe ocean science.
We'll gather important data on two of the key factors
transforming our seas today - pollution and climate change.
Our investigation takes place in the North Sea, sandwiched
between Great Britain and north-west Europe.
We'll sail over 750 nautical miles and visit 16 locations.
Industry has polluted these waters
for longer than any other sea on the planet,
and, in the past 50 years, the North Sea has warmed twice
as fast as the rest of the Earth's oceans.
So it's a bellwether for where they might be headed.
It takes a day to reach the first location.
30 miles off the Dutch coast,
we begin the first of our major investigations.
An experiment that could uncover shocking new depths to one
of the biggest crises facing our oceans today.
We've all seen the pictures of plastic debris
floating in the world's seas, and how it's killing marine life.
But the Pelagia's chief scientist, Professor Helge Niemann, believes
this is just the tip of the iceberg.
Helge's colleagues have recently worked out that there
could be a quarter of a million tonnes of plastic
floating on the surface of the world's ocean.
But that accounts for just a tiny fraction
of the plastic we've thrown into our seas.
At most, a few percent of all the plastic
that we have been dumping in the sea,
we know where it is, and the vast majority of this
plastic has been, well, lost at sea.
And the question is, where did it go to?
Hold it, hold it, hold it... and let go.
The sampling Helge and his team are conducting here in the North Sea
is part of a worldwide search for the 99% of ocean plastic
that's gone missing.
He's using specially designed fishing nets.
We use this net to fish plastic
that is floating at the surface of the ocean.
Skimming the surface of the ocean
and collecting everything in one place. Exactly, exactly.
When we take the net out of the water to inspect our trawl,
at first sight I can't see any plastic...
Lots of goo!
..but it is here. It's just fractured into tiny fragments.
This white thing here, that's a piece of plastic.
There's a smaller one.
There's two pieces.
And is that normal? Is that what you expect for this sort of ocean?
Unfortunately, yes.
A look under the microscope shows the tiny fragments of plastic
in extraordinary detail.
These little white specks, it's pieces of plastics.
What you can see, it already has a rough surface,
it is already starting to fall apart.
You can see it's really smashed up, that it's been bashed around.
Yeah, it's been bashed around.
Exposed to sunlight, saltwater, wind and waves,
plastics become brittle.
You can see in this irregular surface how, actually, microplastics
are being formed because the very top part here will break off
and then you have an ever-tinier piece of plastic that is coming
out of this. If it had been left in the ocean, it could have
broken again and broken again.
Just one plastic bag in the ocean can disintegrate into over a million
of these microplastic pieces,
which then sink below the ocean surface.
So what have we got on the screen here?
So this is a tiny piece of microplastic.
Very high magnification on this,
and we see a planktonic creature.
Sometimes, you see like a small, entire ecosystem
that is living on this.
Microscopic creatures and plants called plankton
form the foundation of the ocean's entire food chain.
And here in Helge's samples, they're living side-by-side
with green flecks of microplastic.
Other scientists have recently discovered
something even more sinister.
Zooplankton organisms can also ingest microplastics
if they're small enough.
So these are the tiny animals that hang about in the water.
Exactly. Very, very little ones.
So this is the base of the food web in the marine ecosystem.
So they have been seen to eat plastics directly? Yes, precisely.
It sounds as though these things
are finding their way up the food chain.
Yeah, on the West African coast
a substantial fraction of all the sardines that are caught
have plastic particles inside them.
Scientists don't yet know how harmful microplastics
will be when living organisms consume them.
They could simply pass through the gut without causing any harm.
Or they could transport toxins,
the effects of which we'll discover later in the voyage.
But there's another equally worrying fate for these tiny fragments.
Helge's research is revealing what happens to them
as they break down even further.
The end of the chain is something that we just start to grasp,
is that these plastics can go into this nanoplastic phase.
So basically things that are smaller than 1,000th of a millimetre,
so really, really tiny,
and now we are wondering whether at least a substantial
fraction of this lost plastic that we can't account for,
whether this has ended in the nano phase.
Plastics are designed to be stable, so they don't break down
in the environment.
But Helge believes that at this tiniest of scales, plastic changes
and becomes chemically reactive.
This is such a new discovery that Helge and his team don't yet know
exactly what effect these reactive nanoplastics will have.
Nano-sized particles can also in time be transported inside the cell,
and what happens then is something that we don't know.
So we can only make an educated guess because it's a molecule,
so it can interact with the cellular machinery.
Eventually, this will not happen only to ocean creatures,
but the likelihood that we also have nanoplastic particles
inside our cells is increasingly getting higher.
It's early days, but Helge suspects that in the long-term, nanoplastics
could do more harm than the larger plastic debris
that's making all the front pages.
Whilst Helen investigates the plastic pollution crisis out at sea,
I'm inland to discover the impact our actions
are having on the animals at the top of the North Sea's food chain.
Over the past decade, scientists have noticed an increasing number
of porpoises and other marine mammals washing up
on the North Sea's beaches.
So I've come to Holland, where they recover more dead
porpoises than anywhere else along the North Sea coast
to try to find out what's killing them.
A week ago, a harbour porpoise washed up onto a Dutch beach, dead.
Today, she's at the University of Utrecht,
and I'm here to help examine her corpse,
to try to discover exactly how and why she died.
The harbour porpoise is the most common marine mammal
in the North Sea.
Over 300,000 of them form the top of the North Sea's food chain.
Marine biologists regard them as a sentinel species that can help
reveal the health of the oceans.
Whatever is happening in these waters should be evidenced
inside their bodies.
So I'm joining marine biologist Lonneke IJsseldijk to perform
a porpoise autopsy, or necropsy.
Lonneke, hi. Hiya.
Nice to meet you. And you.
The aim of the necropsy is to determine
an animal's cause of death.
The first thing I get is this is just such a beautifully adapted
animal for the sea. Yeah! Beautifully smooth and just, yeah.
Yeah, she is.
The necropsy begins by ruling out the most common way
that humans kill porpoises -
catching them in fishing nets.
Almost 2,000 harbour porpoises die
trapped in nets each year.
But our female porpoise doesn't have the telltale marks
on her skin, so we can be sure that fishing nets didn't kill her.
Scientists also know that toxins humans have put in the North Sea
can have a dramatic effect on these mammals.
So have they impacted the life of our porpoise?
To find out, Lonneke's first step is to run the animal through a
CT scanner to check for any congenital deformities.
The CT scan gives us already a look inside the animal.
Oh, that is beautiful.
Yeah. It gives us a couple of things that I find very striking.
Obviously, they don't have hands like we do - no fingers -
but still, within the pectoral fins...
Yeah. ..you can see that the same structure as our hands.
Yeah, absolutely. Yeah.
That's a five-fingered hand. Yeah.
A bit like every other mammal.
It's a mammal. It's just a marine mammal.
It's also confirmed that there's no abnormalities in the bony structure.
Our porpoise has a healthy skeleton, and she's young,
so something has killed her.
I have to move her onto her side...
And as we perform an external assessment, we find our first clue
as to why she died.
She looks a bit skinny, erm, you see,
so this area is where the big muscle is -
the longissimus dorsi, the muscle that makes sure that she can swim -
and obviously they need to have power.
That looks a bit hollow there.
It is. A bit too much, if you ask me.
So, on first inspection, you would guess that she's underfed?
She's underweight, but not totally emaciated.
And the reason why may become apparent when we open her up.
With a nice sharp knife it will get us all the way through easily.
So, to open the animal up...
..just make one cut all the way down.
Here's the blubber.
Now, that looks to be about a centimetre thick.
Is that what you'd expect?
Well, it's not enough.
Of course, the fat here is not just to maintain the shape,
smooth shape, it's an energy store.
Yep. It's an important part of the health of these animals.
Yes, absolutely. And that is under what you'd expect.
Yes. So this is evidence that this animal is underweight, underfed
for some reason? Yes.
To establish why the porpoise is so thin, we take
a look at what she's been eating.
We're going to leave that
and move... The stomach. ..to this table.
I hope we don't find any plastic bags, I tell you.
This is the end of the oesophagus,
and we're just going to go right down.
There's not much in here.
Pretty empty, eh?
Completely empty.
So it hasn't eaten anything in the last... Well, not
in the last couple of days.
That's not how it's supposed to be, obviously.
It must have been a bit ill.
This was a starving animal. Yes.
So it was both skinny... And starving.
..and it was starving.
Our porpoise was struggling to sustain herself.
We investigate the rest of her organs to find out why.
I'll start dissecting into the throat area.
We're now taking the whole of the trachea
and the larynx and the lungs.
Go right into the lung? Yeah. You just follow the bronchi,
the main bronchi goes all the way...
Oh! Oh, ho-ho-ho, look what we've got. Did you find something?
Oh, yeah.
Oh, my goodness.
This thing has got absolutely loads of parasites.
Where did it come from? They're right inside there.
Look at that. Oh, my goodness.
The poor thing.
Now, what sort of animals are these? They're nematodes.
Roundworms?
Yeah, we call them lungworms.
Nasty little worms - or big worms,
right the way... You can see them.
Now, that can't have been very comfortable for her.
No, erm, of course not.
Can you imagine having something crawling in your lungs?
That's quite a load, isn't it?
It is, yeah.
But still, for a porpoise, for an adult porpoise,
we've seen them with a lot more.
Oh, my goodness.
And look at that. That's... Oh!
Most wild mammals have lungworms.
They can spread from porpoise to porpoise
if they accidentally swallow infected faeces.
But only when an animal's immune system is weak
can parasites truly take over.
Now feel this.
Here.
There, you feel a nodule... Ah, look at that. Look at that.
And that's where the parasites cause inflammation
to the tissue around.
And this piece of lung is then not functioning.
So with this animal, we saw an empty stomach,
no recent feeding. Parasites in several organs
and lung inflammation.
So, overall, it's not a healthy animal.
She was definitely ill.
We found clues that our porpoise may have had a weakened immune
system, which could point towards something even more concerning.
To find out what's happening,
we send off a blubber sample to test for toxic chemicals.
So here's a nice piece.
I'm just going to lay it here and you just... I'll fold it up. Yep.
So what we have in here is potentially our crucial evidence
that toxins might have been involved in the demise of this animal.
Yes. Blubber is a good sample to test.
Back on board the Pelagia,
I'm working with Helge and his team on the next stage
of our investigation.
We're exploring the depths of the North Sea for answers
to the spiralling problem of micro and nanoplastics.
Helge uses the ship's workhorse instrument,
the CTD rosette, to search for them.
The CTD is such a simple idea, and yet one of these rosettes
is to an oceanographer what a telescope is to an astronomer.
This is how we built up our picture of the oceans,
and thousands of oceanographers on hundreds of research ships
have sent these tubes down into the ocean and they've captured
a moment in time and a place in the ocean, and they've brought
it back and then they've shared that information with everybody.
24 specially designed bottles allow the crew to collect water samples
at different depths
to discover how much plastic is here
and how it interacts with living organisms.
So it's basically a tube which has a lid at the bottom
and a lid at the top. So the water just keeps moving...
Exactly. ..through the tube. Exactly.
It keeps moving through the tube.
Then, at a certain depth, you can tell the program,
"OK. Fire this bottle. Fire this bottle."
Clunk - close like that.
And then you have that parcel of water captured in this tube.
CTD rosettes, just like this one, have collected plastic fragments
from depths of 4km.
When we retrieve the Pelagia's CTD,
it's not just microplastics we find inside.
Helge is one of the few scientists who collects the micro-organisms
found in sea water that interact with plastic at sea.
Hidden in the water samples he's collected are marine fungi,
just like these captured by other research teams.
I associate fungi with, you know, mushrooms and things in forests.
What are they doing in the ocean and why are they interesting here?
Fungi are extremely good at breaking down very complex organic matter
such as wood, for instance. In the ocean they are quite understudied,
but we have a good...let's say feeling
that some of these fungi in the ocean
might be able to also degrade plastics.
So, basically, these plastic strips are like little fishing lures,
so we're trying to attract fungi to settle on the plastic
and then possibly also to use it as a fuel,
so to eat up the plastic.
You can see here is some slimy stuff around it
and this is a fungi colony. This is also a fungi colony.
So these are the guys that are living on plastic.
Whether they can also make use of that plastic
we still have to verify, but this is at least a clear sign
that there is fungi that are growing
on those plastic pieces in the ocean.
If it turns out that fungi can eat away and use plastic as fuel,
does that help? Personally, this is my hope,
but we don't know. So this is something that we are trying to
figure out. This eating of plastic by microbes,
does that take up a substantial part of the plastic that is being put
into the ocean? And my hope is that, yes, indeed it is
because it would be very sad if the ocean is just a trash bin
where stuff is ending up, but we will never get out.
Helge's ground-breaking work is in its infancy, but it highlights
how - if we stop dumping plastic into the sea -
fungi could potentially make a start at cleaning the ocean.
We are continuing our comprehensive health check of the North Sea
on one of the major rivers that feeds into it. The River Thames.
Here on the site of London's old Docklands,
geochemist Dr Chris Vane is worried
that a chemical banned across the world 40 years ago
is still harming wildlife at sea
and could even be harming us.
Hi, Chris. Hi there.
Nice to meet you. How are you?
'We're here to take a sediment core of the Thames mud.'
Come on, then. Let's go and see some silty mud!
The class of toxic chemicals we're looking for is called PCBs
or polychlorinated biphenyls.
I'm just going to push this so that we capture a record
of the pollution through time.
So I'm now going to carefully lift it out
and then we'll measure the PCBs.
The PCBs have been around since the 1930s, 1940s.
They were used extensively in hydraulic fluids and also
in electrical goods, and they're designed in their chemistry
to be very persistent. Mm.
And that unfortunately is one of the problems,
is that they don't break down.
Once it's in the environment, you would have to dredge out
the entire banks of the Thames. Yes.
Despite environmental science's great victory in getting PCBs
banned in the '70s and '80s,
they are still entering the environment from rubbish dumps,
from the paint on old bridges, and from building sites.
Chris has measured almost 2mg of PCB per kilogram of sediment
from this exact spot -
one of his highest-ever recordings.
What do they do to organisms? Well, they're harmful to organisms
at certain concentrations.
When PCBs enter living cells, their chemical structure
allows them to slot inside receptors usually used by hormones.
If a PCB locks in to a hormone receptor,
it can block or mimic the hormone's signal,
confusing the body's finely tuned messaging system.
The toxicity of PCBs was made clear in 2016 when a killer whale, known
to scientists as Lulu, was found dead on a Scottish beach.
Scientists found 20 times the level of PCBs known to harm marine
mammals in her blubber, more than enough to make Lulu sterile.
Not a single female in the group she belongs to has given birth
to a calf in the past 25 years,
and the group filmed in this rare footage will soon die out.
So how did so much PCB end up in Lulu's body?
Well, it's all due to a process called bioaccumulation, which sees
chemicals getting progressively more and more concentrated
as they pass up the food chain.
Step one begins with tiny animals and plants called plankton,
and they get the toxic chemicals in their food on the sediments
on the ocean floor.
Then, along comes fish and they graze the plankton.
Now, because fish store these chemicals in their fat,
the chemicals are now locked into the food chain.
Along comes a penguin and eats lots of fish.
And then a hungry seal come along and eats some penguins.
And at each stage, the concentration of these chemicals is becoming even
more concentrated. And at the top of the food chain,
you've got big beasts like killer whales
who consume 300kg of food a day.
And the end result is that the concentrations of these toxic
chemicals in the fat of a killer whale are now thousands of times
greater than in the sea water it swims in.
Because of their persistence and their bioaccumulation
through the food chain,
40-year-old PCBs are still poisoning killer whales today.
Scientists predict that, over the next century, killer whale
populations off Western Europe, North America's west coast
and Japan will collapse.
These are all places where the industrial legacy of PCBs
is at its greatest.
But killer whales aren't alone in eating lots of fish.
A fifth of the protein humanity consumes comes from seafood,
and as mammals, we share the same hormone receptors that PCBs
can interfere with.
So could the threat that PCBs pose to killer whales
pose a threat to us, too?
We humans sit at the top of a global food chain.
I want to know how much of the man-made pollution currently
affecting marine life is making its way into us.
In go the noodles...
One of the most well-known pollutants
at large in ocean ecosystems is the heavy metal, mercury.
Like PCBs, mercury is a product of human industry and can
bioaccumulate in top marine predators.
But there's more mercury in a single
tuna steak than PCBs, so it's easier to test for.
I'm doing an experiment today to see if even this small amount of tuna
can affect the level of pollutants in my blood.
Mercury poisoning can cause brain damage, and a baby developing
in the womb is particularly vulnerable to its effects.
Oh, now... That is so good.
This is the third tuna steak I've had in a week,
and that's just one steak more than is recommended by the NHS
if you're pregnant. For ten days before this,
I didn't eat any fish or rice, so any mercury in my blood
should have been taken up by my organs or flushed down the toilet.
Last week, I had my blood mercury levels measured
at the Charing Cross Hospital in London.
I'm supposed to say it's only a small scratch...
Today, Dr Nick Martin is measuring them again.
I brought my sample for you. Thank you.
So this first sample is the baseline sample,
the one I gave a week ago
when I hadn't eaten any fish or rice for ten days,
and that should be negligible.
This one here is the first sample. Right. 7.6.
And this one here is the second sample, so 18.9.
The three tuna steaks I've eaten in the past week appear
to have doubled the amount of mercury in my blood.
Although it's still well within safe levels,
this is evidence that we bioaccumulate toxins
just like killer whales.
So it's an increase,
it's a slight increase, still within what you'd expect
in a normal range, but it does show that the tuna contain mercury
that I have now taken onboard. Yes, that's correct.
So it's very clear that the mercury that was in the fish that I ate
has made its way into me.
What concerns me more, though, is chemicals like PCBs. About 80%
of the PCBs that have ever been produced are unaccounted for.
They're still in the environment waiting to leach their way out.
Even though PCBs were banned many years ago, they're still finding
their way into the sea and into us.
In the past 40 years, the rate of diabetes around the world
has doubled, and the sperm counts of men in the Western world
have fallen by a half.
Scientists worry that both these trends could be linked
to the disruption to our hormones caused by PCBs and other
hormone-disrupting pollutants.
Unless we find a way to stop these chemicals entering the oceans,
the problem is only going to get worse.
Back on the ship, Helge believes there's a connection
between the spread of plastics in the ocean and the spread of toxic
chemicals like PCBs.
So he's helping to create a map showing the spread of plastics
around the North Sea.
At every station we are doing this kind of fishing,
so, therefore, we are filling this blank map with new data.
Helge suspects that microplastics can absorb toxic chemicals like PCBs
and act as a kind of raft that can carry them
on the ocean's currents.
Some of these compounds that are in plastic,
like, for instance, flame retardants or so, these can also leach
out of the plastic and then go into the food chain.
This time-lapse shows how plastic spread when, in 2019,
a ship off Germany's northern coast
lost more than 340 containers in high seas.
It reveals where the UK's plastic waste and toxic chemicals
like PCBs will likely end up.
In one of the most sensitive marine environments on Earth - the Arctic.
Scientists studying polar bears in the Arctic believe that pollutants
such as PCBs are making it harder for them to reproduce.
So far, our ocean autopsy has demonstrated the huge impact
of human industry on significant parts of the North Sea.
We find micro and nanoplastics not just on the surface,
but all the way to the sea floor.
And human-made pollutants like mercury and PCBs
can travel from land to sea and enter the marine food chain.
Now, there's evidence that our global impact is so heavy
that we're depriving our sea
of the very thing life needs to survive - oxygen.
This is a lovely little globe,
which is a self-sustaining ecosystem,
so that means everything in here is recycled.
There's only a few things in there.
There's these tiny little shrimp,
there's algae, and there's bacteria. And everything
that those little shrimp and the algae and bacteria need
for life is just cycling round and round.
One of the most important things in here is oxygen,
and so there'll be some oxygen in the air up here,
some in the water.
When they photosynthesize, the plants will give it out
and then the shrimp will breathe it back in when they respire,
and then it'll go round and round.
And so, in theory, these little shrimp have everything they need
for life, all locked up in that. All they need is some sunlight.
Just like the life in this globe, life on Earth forms one
interconnected ecosystem.
One of the crucial features in this global ecology
is the level of oxygen in the ocean.
If you think about nature harvesting the sun's energy, we normally think
about trees and meadows,
but that's only half the story, because fully half of Earth's
sun harvest comes through these
and these are the phytoplankton.
They're tiny - too small to see individually,
but they're doing exactly the same job.
And it's an amazing contrast.
If you think about a tree, it's a huge organism that lives
for tens or hundreds of years.
It's fixed in one place.
And yet these are the rainforests of the ocean.
Together, these tiny life forms
supply more than 50% of planet Earth's oxygen.
That's more than double the oxygen produced
by all the world's rainforests combined.
The plankton forms blooms that are so large,
we can even see them from space.
What's going on here is that there is a bloom, a phytoplankton
bloom, which means that loads of tiny single-celled plant-like
organisms have suddenly got the right conditions to grow
all at the same time.
And the reason for that is that cold, nutrient-rich water
has come up to meet the sunlight
and everything is there for life to explode.
These satellite photographs show plankton blooms in the Yellow Sea
off South Korea.
In the Bering Strait between Russia and Alaska.
And in the Black Sea, off Turkey's northern shore.
Remarkably, these plankton blooms stretch across the world's oceans
and pulse in and out with the seasons.
So here we are in summer now in the northern hemisphere,
there's almost no ice.
And then it goes into winter and there's a little...
..extra little puff of life.
And then when the spring comes, suddenly the ocean lights up.
So every year there's a cycle like this.
This is the Earth breathing.
But these cycles are knocked out of kilter when the nutrients
contained in fertilisers run off from farms and feed super blooms
of plankton in the ocean.
When these plankton die, they sink and rot,
consuming the sea's vital oxygen.
In 2019, an 8,000-square-mile stretch of sea at the mouth
of the River Mississippi was classified as a dead zone,
and scientists fear that a combination of excess nutrients
and warmer waters could see oxygen levels drop so much in many parts
of the ocean that creatures like sharks and turtles
will suffocate, while jellyfish will thrive.
If we can breed new strains of crops and develop more sustainable farming
methods, there's hope that we'll be able to spray
less fertiliser onto our fields
and revitalise the dead zones killing our seas.
In the necropsy lab, we're taking a look at a wonder of the marine
world - how a porpoise is able to navigate the darkness
of the North Sea.
Toothed whales like this harbour porpoise have swum in the oceans
for millions of years
and, in that time, the have evolved a unique way of perceiving
the world - echolocation.
Echolocation is a porpoise's sixth sense.
They use it to hunt, socialise and navigate.
I'm investigating how this remarkable sense works.
Right! Now, this is where it gets really interesting.
Here is the head of the porpoise, and you've cut
right down the middle. Yes. So we can, very carefully...
Open it up. ..reveal what's really happening in here.
The blowhole is essentially our nose. Yeah.
So it's just moved up to the top. Just below the blowhole,
we have some specialised structures called phonic lips.
These are like our vocal cords, but not quite the same
cos it's a different structure,
but they're able to make these vibrate. Yes.
And produce a clicking noise or a bzzz noise. Yep.
At very high frequency.
It's a high-pitched buzz or a series of clicks that are sent forward
off the skull here through this fat tissue here, and projected forward
either in a wide beam or a small beam.
And it's then returned from the object along this acoustic
fat that runs along the jaw into the auditory system here.
These animals see with sound. Yep.
And the closer the subject comes, the quicker the clicks
will reach and bounce.
Ping, ping! That is sent forward.
Ping! And then ping, it returns from the fish,
and if it's far away it'll be a longer return.
If it's shorter, it will be ping-ping, ping-ping.
And it's so finely tuned that they can tell what other animals
are there, who they are, if it's their mates or a calf.
They can tell prey, how far away it is, what the prey is, how fast
it's going, which way it's going, and all in total darkness.
Now that is a super sense.
Porpoise and dolphin echolocation gives these creatures abilities
that we can only marvel at.
They can listen to the reflected clicks of other animals
to check out what their neighbours are looking at.
And some reports suggest that they can even see
inside each other, using their clicks as ultrasound
to look at unborn pups in the womb.
Could our actions in the sea
compromise these remarkable abilities?
Over 3,500 wind turbines and almost 200 oil rigs
have transformed the North Sea into an industrial landscape.
With so much industry, I want to hear for myself just how noisy
the water is beneath the surface.
To do that, we'll need to get as far away from the sound
of our ship as we can.
So I'm now in a small boat, maybe 500 metres away from the Pelagia,
and it's beautifully peaceful and really quiet.
And the reason I'm here is that, even though it's quiet
and peaceful up here, it doesn't necessarily mean that it's quiet
and peaceful down below.
And the reason for that is that the ocean surface acts
like a mirror for sound. Sound from the air comes down and bounces
off the ocean and goes back up, and sound from underneath comes up,
hits the ocean's surface and bounces back down.
So the ocean surface is effectively a barrier for almost all sound,
so we have no idea what's going on down there
and it is a different acoustic world.
But you can listen in with the help of a bit of technology.
So what I've got here is a hydrophone, it's an underwater
microphone, and it's attached to a little device here
that will play out in real time what's happening under the waves.
So this is our ear into the ocean,
and we're going to see what there is to listen to round here.
So the first sound is the sound of bubbles being formed
as it splashed, and I've got quite a lot of cable here.
DEEP PING
That's interesting.
PINGING
So, as it goes down, there's a new sound.
What's that?
PINGING CONTINUES
You can hear this, "Ooh."
PING
SHE MIMICS
And it's really clear on here, so something
down there is making a sort of deep pinging noise,
and I think that is too low a frequency to be our ship's
multi-beam. So there's an oil platform just over there -
it might be they're testing something and it's doing that.
It is straight out of Star Wars.
PINGING CONTINUES
It must sound even weirder to a fish, that.
Human-generated sounds like the noise I've just recorded
have an impact on marine animal behaviour.
One of the saddest things about noise pollution
is that actually things like porpoises, for example, they use
sound to communicate all the time
and, first of all, if it's noisy, they can't hear each other
but, secondly, just like us,
if you hear a really loud noise, it's stressful.
They tend to move away from it.
Our actions are making it more difficult for porpoises
and dolphins to sustain and reproduce in noisy waters.
And the loud booms made when we hammer the foundations
of wind turbines into the seabed can deafen them.
Thousands of porpoises washed up on North Sea beaches just last year.
We've sent away blubber samples of our porpoise because we suspect
that chemical pollution could be partly to blame.
And as our necropsy advances,
it becomes clear that we may
have more than one porpoise death to explain.
Oh, now, what happened there?
You just pressed the mammary gland
and we have a little bit of white fluid. Milk came out.
Milk. That means she had a calf.
She was lactating for a calf,
which unfortunately can't go without milk,
so I'm afraid that means that she was either unsuccessful
or at least her calf did not survive.
So we potentially have two animals.
Yeah, unfortunately, I'm afraid that's the message.
That's sad. That's very sad.
So the PCBs, if they're in this animal, are going to be passed
directly to the calf in the milk.
Yes. Adult females, as she is, can off-load
and this is the way of off-loading.
The off-load would mean they can get rid of their PCBs
by potentially feeding them... Feeding them to the calf.
That's a tragedy, isn't it?
Because PCBs dissolve in fat,
our porpoise will have inadvertently off-loaded them
into her first calf's milk.
When a new mum starts to breast-feed, as much as 80%
of the PCBs in her body fat can pass into the fat in her milk,
and mums can also transfer PCBs directly
to a developing foetus in the womb.
This is the left side of the uterus coming out,
and, well, unfortunately I have to tell you that it feels
like there is actually something in it.
Don't squeeze too hard. Just softly. You feel...?
Yeah. Yeah. Yeah, yeah, yeah.
Yeah, yeah. Yeah.
So she is pregnant.
She was. So it's a very sad case,
but, yeah, let's, uh,
let's figure out what's going on.
Obviously, it's very... Oh, I can... Oh, look, look.
Oh, yeah. There it is.
Aww. Very fragile, still in its sac.
Look. Tiny little foetus.
It's tiny. Mm.
How old would you say that is?
So this will be... A few weeks?
No, a little bit more. I would say maybe up to two months.
What-what a mess. What a mess!
So there's two things that the PCBs do.
On one hand they can produce reproduction failure,
and we have strong indications that that was the case.
On the other hand, it's dysfunctioning of the immune system,
so high parasite loads. With that also general debilitation
from not eating and being emaciated.
So the animal was healthy enough to be pregnant, but clearly not
healthy enough to carry it through.
Our porpoise was in a weakened state because she was trying to eat
for herself, her newborn pup and the foetus in her womb.
We're nearing the end of our investigation today
into how this animal died,
and already we can see that she was underweight for her size.
She hadn't eaten anything for a few days before she died.
She had a pregnancy, which had obviously failed,
and she had parasites in her lungs.
All in all, a pretty stark picture.
A week later, I've returned home to England
and Lonneke has the toxicology results.
Hi, Lonneke. Hi, George.
Now, we were particularly interested in seeing how much PCB
she had in her. What were the results?
The PCB levels were relatively low in the blubber of this animal.
Through her lactation she was able to off-load,
but it does mean that the calf that's suckling is getting
high doses of these PCBs in, at a very young age, so...
And that means that her newborn, who is extremely vulnerable,
will get an enormous amount of this stuff.
You know, bang, right at the start of her life.
First calf especially gets the highest doses of something
like a chemical cocktail, which comes through the milk.
Lonneke's necropsies show that one in five
female porpoises found on the North Sea's beaches
have suffered a failed pregnancy.
And she believes that the harmful effects of PCBs kill most
first-born porpoises in the North Sea prematurely,
including the first-born calf of our porpoise.
How do we stop PCBs from getting into the seas in the first place?
I mean, they're persistent pollutants.
They persist even though that they've been banned.
It's a very difficult question
and there's not a straightforward way to go.
The $64,000 question, Lonneke, how did she die?
I think the emaciation was something
that really was the main finding. Being pregnant
but also lactating means that she really has to invest
in her offspring, and that might have come at her own cost, so.
OK, Lonneke, thank you very much.
Thank you.
The necropsy has revealed that our porpoise lost weight
as she struggled to feed both her foetus and her newborn calf,
becoming weaker and weaker until she eventually died.
Although we can't blame PCBs directly for her death, or say
exactly what killed her, we do know that PCBs in the North Sea
are having an impact on calf survival.
And the evidence we've seen here indicates that PCBs
could have been responsible for her first-born's death
as she off-loaded PCBs into her milk.
We're finally beginning to understand the damage plastics
and PCBs are inflicting on life in the sea.
But there is another set of chemicals that we use every day
that are also toxifying our water.
Scientists are now realising that other harmful chemicals
are making their way into our waterways.
Chemicals deliberately designed to be biologically active -
pharmaceutical drugs.
Alistair Boxall is professor of environmental chemistry
at the University of York.
He runs a project measuring the drugs flowing from rivers
into the sea in 105 countries.
I've joined Alistair at Hampton Court Bridge in south west London
to find out how many pharmaceuticals make it into the River Thames
and ultimately into the North Sea.
So, here's a good spot. Yeah, this is perfect.
Alistair samples the water for 61 different pharmaceuticals,
just a fraction of the 1,900 medications
licensed for use in the UK.
How do these compounds actually make their way into the Thames?
When we take a pharmaceutical, we will take it into our body,
we might metabolise that pharmaceutical in our liver,
and then what we'll do is we'll excrete either in our urine
or our poo, and that will go down the sewage works.
If you take something like the anti-epileptic drugs we use,
they're not removed hardly at all by the way sewage treatments work.
So what sorts of drugs are you looking for?
And what do you find?
They include things like antibiotics, anti-depressants,
things used for diabetes, things for headaches,
anti-inflammatory drugs. So a real mixture.
You just don't think about it because you take it,
you think it's metabolised and it's gone away.
It hasn't gone away,
and it's ending up in the Thames and elsewhere,
affecting the wildlife there.
So there's some really cool data from the States
where in the laboratory they added anti-depressants to a tank.
The tank contained a female and a male fish, and they found
that they didn't reproduce like they would normally.
Now, if that's happening in the river,
that could be really important in terms of the survival
of the fish populations.
I find it almost unbelievable that this is a hidden problem
that we're only now just beginning to cotton onto.
Alistair's analysis of the Thames samples
reveals some startling results.
What was the top hit? The top one was a drug used
for diabetes called Metformin.
We saw a concentration of 290 nanograms per litre,
and that works out at about 220 pills of Metformin.
So here we have 220 tablets
and they're flowing under the bridge...
..at Hampton Court every hour. Yep.
So every day there'll be over 5,000 tablets going under that bridge
and then out through the estuary into the ocean.
That just seems almost unbelievable.
I would say to people watching this, if you have unused medicines,
don't throw them down the toilet.
And that's what happens a lot.
People just empty... Take it back to your pharmacy.
The pharmacist will take those unused medicines
and they will ensure they're disposed of properly.
If we're not careful, pharmaceuticals could join plastics
and industrial chemicals as major pollutants harming marine wildlife.
Human-made pollution is directly impacting individual creatures
in the sea, but our heavy footprint is also posing a worldwide challenge
to the whole ocean ecosystem.
Increased carbon dioxide in the atmosphere
is heating up planet Earth.
Since the Industrial Revolution,
the world has warmed by one degree Celsius.
The UN has just published its most comprehensive ever report
on the threat that climate change poses to our oceans.
If we warm the Earth by just one degree more,
the consequences will be devastating.
I'm investigating the impact of this warming world
from here in the North Sea.
Its waters have warmed twice as much as the global ocean
in the past 50 years.
Whatever's happening here can give us clues
as to how the rest of the planet's oceans might be affected.
One of those impacts is that a warmer world
could drive more extreme weather.
The wind's going to pick up. It's just starting to rain now,
so I think the North Sea has been kind to us for all of...12 hours,
and it is about to regain its normal character.
And I think the weather could be quite enthusiastic this evening.
WAVES CRASH
The North Sea is notorious for its storms.
The season begins in autumn,
after the ocean has basked in a long summer of sunshine.
The energy on Earth comes in from the sun,
and then it travels through the Earth's system,
through the ocean and the atmosphere,
and eventually, it gets radiated away into space.
So there's a flow in and a flow out.
And the problem of the greenhouse gases like carbon dioxide
is that they slow down the flow out.
So more energy is coming in than is leaving.
That's where global warming comes from.
It's that additional energy that we're accumulating every year.
And the next question is, where does it go?
And the answer, and we can measure this,
is that since 1970, 93% of that additional energy
has ended up in our oceans.
One of the predictions for a warming world is that hurricanes,
because the ocean is warmer, they'll have more fuel,
and so they'll be more intense.
WIND GUSTS
A large hurricane can expend as much energy as 10,000 nuclear bombs.
And a hotter world will likely increase their power.
As night falls, the windstorm sweeps through.
PhD student Tim de Groot is worried that his sampling is at risk.
We just talked with the crew. Like, they are in charge of the safety.
If they think it's unsafe enough, then we won't do it.
In my opinion, we can always do it.
Up on the bridge, the captain is monitoring the wind.
We're encountering a storm now.
On the Beaufort scale, minimum force eight...
..getting to nine and sometimes peaking to ten.
When you reach 12, it's going to be a hurricane.
We have slightly less, but it's a rough storm.
60mph gusts create a heavy swell...
..so the crew is struggling to bring the CTD in safely.
And my kit is at risk, too.
I have this nightmare about my science kit sliding
all over the floor, you know, as the ship rocks, things falling off
and getting broken and hitting things.
CLANGING
It's too much for us to do the job safely,
so we cancelled all the operations for the night.
The storm has deprived the team of an important set of data.
I'm hoping the waves haven't put an end to my science plans as well.
So I'm coming into the lab space here.
And...the waves haven't got to it.
Everything is still there.
And still secure.
So I feel a lot better now.
As the world warms and sea levels rise,
more powerful storms will batter the British coast,
bringing more floods with them.
WAVES CRASH
Scientists predict that by the year 2050,
once-a-century floods could happen as often as once a year.
Six days into the voyage, we've arrived at a spot that reveals just
how dramatically the North Sea's coastline has changed in the past.
It's a spot made familiar by the shipping forecast.
Dogger, south-west, four or five, becoming cyclonic.
Then west later, seven to severe gale nine,
perhaps storm ten later.
Dogger Bank is 150 miles east of Whitby,
and the biggest sandbank in the North Sea.
I'm up on the ship's bridge with Chief Officer Len Bliemer,
to take a closer look.
So that's our position at the moment.
You can see we are right on the edge of the Dogger Bank.
You can see the depths in metres.
The Dogger Bank is, like, 15 to 25 metres.
That's really shallow. It's really shallow, yeah.
Just 9,000 years ago,
our ship couldn't even have sailed above the Dogger Bank
because this whole area and everything around it
would have been land.
And this is a reconstruction of the area at that time.
And you can see Britain on the left here,
and then, Norway and Europe on the right.
And in between, instead of the English Channel and the North Sea,
we can see there's this great big plain here,
and this was Doggerland.
The thing I love about this map is you can see that there were hills.
You can see the rivers and this big lake in the middle.
Humans lived here. We've got archaeological artefacts.
Fishermen have been dredging up things like stone axes from
this area and there are bones of animals that lived here.
We've got the evidence that this was a real place.
But it's not here any more.
And to see what happened to it,
we just have to wind the maps forward in time a little bit.
So this is now 10,000 years ago,
and you can see the big plain of Doggerland is still here,
still looks like a place you could visit,
but over here, this is 9,000 years ago,
and now, this is the end of the last ice age
and sea level is starting to rise.
And as it rises, it covers over the lowest parts of Doggerland
and it keeps rising and keeps rising
so that there's only this little bit left 8,200 years ago.
And then, by 7,000 years, Doggerland has gone.
It's vanished underneath the sea.
The lost marshes of Doggerland
show just how dramatically sea levels have changed
over the North Sea's history.
In just a few thousand years at the end of the last ice age,
melting ice sheets and warmer oceans
made sea levels rise by more than 30 metres.
Today, sea levels are rising faster than at any time since then.
And this time, it's caused by us.
Three degrees of warming by the year 2100
could see major world cities like Miami, Shanghai and Osaka
engulfed by the sea.
At Wallasea Island, near the mouth of the Thames,
just 50 miles from London,
an ambitious project is working WITH nature
to develop a pioneering form of flood defence.
I'm joining Jeff Kew, who oversaw the development of the site.
Hi, Jeff. George, hello! Welcome to Wallasea Island.
Nice to meet you. Thank you. Now, how big an area is this?
Well, Wallasea Island, it's the largest
coastal habitat restoration site in Europe.
So we're standing on a sea wall that was built in about 1500.
To this side, we have the River Roach, which is tidal,
and on the other side, we have Wallasea Island.
And that farmland, or it used to be farmland, is a lot lower.
Yeah, it's lower than sea level.
So we're about a metre and a half below high-tide level.
So we're now coming down off the sea wall,
on to the sea side of the wall.
Now, this is a very simple structure.
It's just an earth bank with a concrete block face.
Yeah, a simple sea wall, but designed on the assumption
that there would always be salt marsh in front.
And what's the problem? Well, I can see bits of the problem here.
Yeah... It's breaking up.
You can see the problem very clearly here.
What's happened is the salt marsh in front has been lost through erosion,
allowing the sea to attack these blocks and erode the wall.
The problem is, with rising sea levels,
this will happen extensively over whole lengths of walls,
and then the whole thing becomes unsustainable.
Jeff's ingenious solution to the crumbling sea walls is to make use
of the miraculous properties of the salt marsh itself.
Jeff's team breach sea walls to the north and east of Wallasea Island
and transform 280 hectares of arable fields
into salt marsh and mudflats.
He's agreed to show me an overview of the work so far.
For us, seeing these images, it's, um...it's fantastic,
cos we're achieving exactly what we set out to do.
If we fly down here gently,
we're heading to the northern breach.
So this is the breach which takes the majority of water
in and out of the site each tide.
Now, every time the tide comes in, it will drop silt.
All this shiny mud that you can see, that's all new mud that's come in.
So this site has already accreted since breaching.
This silt, carried in by the tide, is transforming Wallasea.
Crucial to the whole habitat is the salt marsh vegetation.
Well, Jeff, this, at first glance, it doesn't look very interesting,
but actually, up close, there's lots and lots of plants here.
Yeah, there's a great diversity of salt marsh plants already growing.
What makes them so useful to us?
They provide quite a dense map of stems,
and what these do is, when the sea comes in, laden with silt,
the silt drops, is trapped by the vegetation,
and then the ground just goes up and up as this silt is caught.
And this enables the salt marsh
to physically go up in height progressively.
And what we think, with rising sea levels,
is that many of these marshes will be able to just keep going up
and keep up with levels of sea-level rise.
So it's a win-win. If we don't try and fight the natural world,
it will help us in the end.
We need to provide space for nature and habitats like this,
and use nature to help us.
BIRDSONG
Thanks to the rewilding of Wallasea Island,
the reserve has become a major new home for breeding birds.
BIRDSONG
Almost 150 pairs of avocets live here year-round.
More than at any other site in the UK.
The growing salt marsh is also the best possible habitat
to combat rising greenhouse emissions.
As it traps silt, it locks away 50 times more atmospheric carbon
than a forest of the same size.
Well, it's hard to believe that what I'm looking at
was arable fields only four years ago.
And it just goes to show, we don't have to defend ourselves
against sea-level rise by using enormous amounts of concrete.
Natural flood defences like this could help fight
the sea-level rise we will face in the coming century,
saving many coastal communities in Britain and around the world.
The extra carbon dioxide in the atmosphere won't just affect
the planet through climate change and sea-level rise.
It has a dramatic effect within the ocean, too.
My own area of research investigates what's going on.
It's the study of ocean bubbles.
We've got these breaking waves on the surface, and they are doing
something really interesting - they're helping the ocean breathe.
So when a wave breaks, it takes little pockets of the atmosphere
down underneath the surface of the ocean.
And it's the big bubbles and these breaking waves,
the ones that we can see, are helping push carbon dioxide
from the atmosphere into the ocean.
WAVES CRASH
The ocean is actually taking up something like 25%-30%
of all the extra carbon dioxide that's going up into the atmosphere.
This natural carbon capture sounds like good news,
but it comes at a price.
A price that threatens the ocean ecosystems
more immediately than a changing climate.
Ocean acidification.
I've got a tank of sea water here
and what I've got down here is dry ice.
So this is solid carbon dioxide that's frozen.
So I'm going to add it to the sea water.
Ooh! SHE LAUGHS
That is a lot of bubbling. Loads of bubbles!
The solid carbon dioxide is turning into a gas.
And as it bubbles through the water here,
making all this lovely vapour,
some of it will be coming out of the water,
but lots of it will be dissolving in the water in the tank here.
So this is a pH metre that measures how acid or alkaline the water is.
And as the carbon dioxide dissolves,
we can see the effects on the pH.
The ocean's pH should be 8.1,
but our sea water reading is rapidly dropping.
This number going down means that the water here
is becoming more and more acidic
as more and more carbon dioxide dissolves into it.
Now, this is just a small tank,
but humanity is currently conducting an experiment
that is very similar to this on a global scale.
The oceans are massive, but the amount of carbon dioxide
we're adding to them is also gigantic.
And even though our oceans are big, we can already measure this.
We know that humanity has already changed the pH
of the entire global ocean.
The carbon dioxide we've emitted into the atmosphere
has increased the ocean's acidity
by just a small fraction of a single pH unit.
That doesn't sound like much, but it's enough to radically alter
one of the most diverse ecosystems on Earth - coral reefs.
Coral covers less than 1% of the ocean floor,
but it supports over 25% of the species in the sea.
The hard parts of corals and the shells of shellfish
are built from a material called calcium carbonate,
one that's particularly sensitive to acid conditions.
How will these creatures cope with a more acidic ocean?
To find out, I've got to wear some protective clothing.
That was quite a dramatic reaction.
Now, what I just put into the tank with these shells
was a really strong acid - hydrochloric acid.
What's happening here is the acid is actually dissolving away the shells.
The ocean is naturally alkaline, and creatures like this
can build their shells quite easily in an alkaline environment.
But once you add an acid, what you do is
you take away the most important building block they have -
calcium carbonate.
So it becomes harder for them to harvest it from their surroundings
and build into their shells.
I left my shells in their acid bath for four hours
and then they've been sitting in fresh water for a day,
and just look at what's happened to them.
That beautiful conch shell has almost been entirely eaten away.
And this is extreme, but it does highlight the point
that for creatures that build their home from calcium carbonate,
it really matters how acid or alkaline their environment is.
And actually, even a small shift could make a really big difference.
This is an extreme example,
but our experiment demonstrates the vulnerability of shells
to a more acidic ocean.
Some waters off North America's west coast are so acidic
that they can dissolve the shells of sea snails called pteropods.
In 2016 and 2017, ocean acidification contributed
to the major bleaching events on the Great Barrier Reef.
Bleaching is when coral ejects the colourful algae
that keep the coral alive.
And scientists fear that all coral reefs could be lost
by the end of the century.
It's already too late to reverse
the ocean acidification we've caused so far.
If our carbon emissions continue unchecked,
then the pace at which our entire planet warms
also threatens to escape our control.
Carbon dioxide isn't the only greenhouse gas.
Next on the list is methane.
Methane is currently contributing about a fifth to global warming.
In the final leg of our North Sea health check,
we're 200 miles north-west of the Dutch coast.
The Pelagia's chief scientist, Helge, and his team
are conducting an important experiment.
They're searching for a methane seep at the bottom of the North Sea.
Methane is an extremely potent greenhouse gas.
It's about 30 times more powerful than CO2.
Methane has a more complex molecular structure than carbon dioxide,
and it traps more heat from the sun.
If a large amount of sea floor methane escapes to the atmosphere,
then the warming effect could be dramatic.
In the 1980s, scientists discovered a form of methane ice
called methane hydrate,
that forms naturally at the bottom of the ocean.
These images show its crystal structure.
Scientists estimate that more than 1,000 trillion cubic metres
of methane ice is frozen away in ocean sediments.
That's more carbon than in all the world's oil and gas
reserves combined.
There's this picture where in the Arctic, sort of locked away in cold
places, there is this huge store of methane and it's just sitting there.
Yeah, if the ocean warms up, then indeed more methane is coming
and then we have a positive feedback loop, so the warmer it gets,
the more methane comes, thus the warmer it gets.
Helge's trying to discover how much methane the gas seeps can
deliver to the atmosphere.
So the team use the ship's sonar to search for spots where they believe
bubbles are leaking from a peat bog buried beneath flooded Doggerland.
On the map here, we've got the place where you last saw it. Exactly.
We're just coming up to it.
OK, and now we are seeing it. Oh, is that it? There it is.
There it is. It is coming.
You can see here on the left as well...
That's a very strong reflection, isn't it?
It is, it's very nice.
Now we've found the seep, I can deploy my own bubble camera.
I'm hoping I can help Helge's research by measuring how big
the bubbles are.
Measuring bubbles is what I do in my professional life.
This is quite a special camera.
There are flashes that only last for 20 millionths of a second.
It lights up a very precise part of the ocean
and it can see all the bubbles, just at that moment.
us, so we have a relatively high chance that the bubbles will
come to the surface.
If we're in the correct spot, my camera will give me
15 chances every second to image the methane bubbles,
allowing me to measure their size.
We're back on board, so it's all right. We're happy!
Now we've just got to see what data's on it.
My pictures reveal the individual methane bubbles climbing
through the water column.
Bigger bubbles float all the way to the sea's surface
and deliver their methane to the atmosphere.
But there are other bubbles that dissolve into the sea before
they can make it to the top.
Can anything in the sea water prevent this dissolved methane
from reaching the atmosphere and accelerating global heating?
To find out, Helge lowers a pump into the water
and pushes 150 litres of sea water through filter paper.
We want to study this, specifically looking at microbes,
which are hovering in the water column,
and while this methane is bubbling through,
they're sitting there, waiting, hungry and feeding on this methane.
You can light methane, so it burns, so there's chemical energy in it.
There's some organisms that can also make use of this chemical energy in
a very similar way as you and I are for instance making use of sugar.
The team carefully remove layers of filter paper from inside the pump.
Sitting on each piece are billions of methane-eating bacteria.
So the big question is actually, how effective are these microbes?
Do they really eat up all the methane?
If not, how much is going into the atmosphere?
The team launches the CTD rosette to take sea water samples
at five-metre intervals,
starting 30 metres down, at the origin of the leak.
It then takes samples in the middle of the water column,
and finally, at the surface.
So we know how much methane is at the bottom layer, how much
methane is at the top layer, and how much methane is in between of this.
And with these concentration profiles, you can then model
how much methane is making its way up into the atmosphere.
So what do Helge's results reveal?
We know that they are quite effective
because we know a lot of methane is being produced in ocean sediments,
but only relatively little is making its way up into the atmosphere.
Helge and his colleagues have found that ocean microbes consume
more than 90% of the methane that has dissolved into the sea water.
His team will spend the coming months analysing how that
figure can change with varying ocean conditions.
Most importantly, as the climate continues to warm,
will these bacteria still do such a good job?
We could have a very, very gradual change and then these methane-eating
microbes I think have a very good chance of multiplying
and then basically taking care of the problem. So they can keep up.
Exactly. As long as it only comes out slowly, they can keep up.
Exactly.
But there is also quite some concern that things may go rapidly,
at least in certain areas,
specifically in regions like the East Siberian Shelf.
All of a sudden, the increase is becoming quite tremendous,
and then you may also have the situation where the methane-eating
microbes cannot keep up.
So if we warm everything too quickly, and the methane gas escapes
too quickly, the bacteria don't stand a chance
and it will reach the atmosphere. Yeah. Yeah, exactly.
Helge's research is an important new contribution to climate science,
and it matters because a sudden runaway release of methane
could lead to a much hotter world.
This possibility is just one of the reasons that the
United Nations wants to limit future warming to half a degree Celsius.
After two weeks on board the Pelagia,
our ocean autopsy is complete.
I've seen first-hand the impact our actions are having
in the waters off our own shores.
But right now, I can't wait to get my feet back onto dry land.
I've returned to Holland to find out
what Helen's learned from her time at sea.
Well, I just got off the ferry from the mainland over in Texel
and I'm just heading to meet Helen.
I'm really keen to find out how she's got on.
I have to say, two weeks on a boat in the North Sea is not
something I'd be queueing up to do!
And there she is.
The Pelagia.
Helen! Hello.
How are you doing? How have you been? How was it?
It was, you know, bumpy in places, but mostly... Bumpy in places?
I'm not a natural sailor, I have to say.
Well, that's when it gets fun, right?
Once the bumps start coming along, that's
when you're really living at sea! Well, let's have a debrief.
The last two weeks, you've seen at first-hand just what
sort of impact we're having out there.
I've not been out in the North Sea before. I've mostly been out in the
open ocean. And the biggest thing I noticed,
it's not just that it's changing, cos that's a natural thing,
it's that it's changing faster than the system can keep up.
I'm just beginning to get a grip on how much stuff gets
washed into the sea. It seems incredible to me that PCBs,
which were an entirely man-made chemical group,
were banned 40, 50 years ago,
but they're still having their effects as they magnify through the
food chain. And when I dissected the
porpoise, I did get a very strong sense of this being a warning
actually, to say to us, "Guys, can you stop doing this, please?"
I think that we're getting close to too many things
changing at once cos the problem is,
the things that are stressing the life, it's not just one thing,
it's not just plastics or just, you know, pollution,
or just the temperature change.
They're getting knocked from all sides.
There must be a different way.
But I think everybody would agree the oceans have been pushed too far.
This is why research ships like the Pelagia are so important because
they let us go and find things out, and the more we understand,
the more we can be really sure that we're making better
decisions in the future.
That's the thing that keeps me at least a little bit optimistic
is that actually now we're starting to have enough knowledge to
really understand. And we need to take those hard choices...
..make those hard choices now.
So what choices do we need to make to protect our seas?
Can we safeguard marine ecosystems by ending our throwaway culture?
Can we ensure that any new toxic chemicals
we invent will not persist through the ocean food chain?
And can we prevent those we've already made
from finding their way into the sea?
Can we limit global carbon emissions to give the oceans
a chance of recovering from their current state?
These are massive challenges, and whether we can make them
is uncertain.
But there are positive signs.
And to see this for ourselves,
we're taking one last trip off our own coast.
We're on our way to a site where human infrastructure
and wildlife successfully exist side by side.
And the sea is very calm, which is good, cos we're going out into it.
It's very good for me. Just a few miles that way.
You're not... You're not a keen seaman! No!
We're sailing out to the Scroby Sands Wind Farm,
just a few miles off the Norfolk coast.
Wind farms have helped the UK to reduce its carbon
footprint by almost 40% since 1990,
and they now produce one fifth of Britain's electricity.
The aim is to raise that to a third by 2030,
but that will require the erection of 5,000 new turbines.
We've seen that the noise produced by hammering turbines
into the sea bed is bad news for marine life.
So the offshore wind industry is under pressure to do
things in a better way.
It's one of those things where knowledge is the thing you need.
There are ways now to build wind turbines that make less noise.
You can put shielding around the outside
so the noise doesn't get out, so if you get them right, you can
perhaps put your wind farm in the best place for it.
You can choose a place where it can have benefits on the local ecology.
So we've got some video here from right underneath one of these
wind turbines, and there's all kinds of stuff down there. Anemone.
Anemones and barnacles, all kinds of shells. Crab coming there.
So the actual structure of the wind turbine provides a home for animals.
People have called them an artificial reef.
On what use to be a sandy bottom here,
there's quite a lot of concrete and rocks and hard substrate
and that's where life like this is really getting a grip.
There's more animals coming, there's lots of fish there,
lots of animals, they'll be eating the fish. You've got seals.
I saw at least three seals.
You can actually see on the video here from a few years ago
and the red line is a single seal that is going from one wind
turbine to the next to feed. So it's basically working its way...
The seal knows this is a good place for fish.
Yeah, it's feeding, doing very well,
and it knows exactly which side its bread is buttered.
Globally, grey seals are endangered, but here in the UK, their
numbers have grown hugely since seal hunting was banned in the 1980s.
British and Irish waters are now
home to half of all the grey seals on Earth.
There's no doubt the wind turbines are changing the ecology,
but if they're changing it to make it more biodiverse
and to bring back wildlife, then... That's a good thing.
..you can see that as a positive thing.
So when I see an offshore wind farm now, I will actually think,
"Well, that could be a little marine park."
Our autopsy of the North Sea has shown that it's in crisis
and that the world's oceans are headed in the same direction.
But it's also revealed that the oceans themselves might hold
the key to their own survival.
We've seen just a few
of the functions that ocean life can perform.
Ocean plankton produces more than 50% of the oxygen we breathe.
Fungi and bacteria could break down and digest plastic and methane.
Saltmarsh plants can fight sea-level rise
and trap carbon at the same time.
Life in the ocean is so diverse that it could fight back
against many of the challenges that we're throwing at it.
But it's at a tipping point.
This is the crucial moment to change our behaviour.
If we leave it any longer, it will be too late.
The fact that that one is only under a week old, it means it's got
lots to drink off its mum and she must be reasonably healthy
and fit. It shows that wildlife can be resilient,
if you give it a chance and you look after it.
That's the one thing that actually offers a huge amount of hope for me
is that if you give the natural world a chance, it will come back.
And if we stop doing all the things that we know
we shouldn't be doing, this is going to happen all over the place.