All language subtitles for Blue.Planet.II.S01E07.Our.Blue.Planet.WEBRip.x264-RARBG.en

(THEME MUSIC PLAYING)

In the course of making Blue Planet II,

we've explored every corner
of the underwater world.

We've encountered extraordinary animals,

and discovered new insights into
how life is lived beneath the waves.

For years we thought
that the oceans were so vast

and the inhabitants
so infinitely numerous

that nothing we could do
could have an effect upon them.

But now we know that was wrong.

The oceans are under threat now
as never before in human history.

In this final episode,

we will meet the pioneers
who are striving to turn things around.

(GULLS SQUAWKING)

People who are helping to save
the ocean's most vulnerable inhabitants

and dedicating their lives
to protecting the seas.

But is time running out?

Many people believe that our oceans
have reached a crisis point.

So just how fragile is our blue planet?

Winter in the Arctic Circle.

Every year, the waters of Norway
are the setting

for one of the greatest
wildlife spectacles in the ocean.

Over a billion herring
pour into these fields.

The Blue Planet II team
spent three years

documenting this astonishing event.

Such a wealth of prey attracts predators

in extraordinary numbers.

(ORCA WHISTLES)

Orcas

and humpback whales.

But this migration
hasn't always been so bountiful.

Leif Notastad is a Norwegian
fisheries scientist.

It's been one of
the most important fisheries

that we had for centuries
along the whole coast of Norway.

But in the late 1960s

the herrings that we see around us here
was on the brink of collapse.

50 years ago,
fishing was so intensive

that the herring had all
but disappeared.

Orcas were seen as rivals

and hundreds of them were killed.

It was only after the Norwegian
government imposed severe restrictions

that the herring began to recover.

(GULLS SQUAWKING)

Today, this is once again
an immensely productive fishery,

closely monitored
by teams of scientists.

Marine biologist Eve Jourdain

is one of the resident orca experts.

From 1982, orcas got protected in Norway

and we have clearly one of the largest
orca population in the world out here.

There are now over
a thousand orcas here.

But with so many mouths to feed,
including ours,

can the mistakes of the past be avoided?

To answer this vital question,

Eve and her team are using
multi sensor camera tags.

With the tags we try to see
how the orcas interact with their prey.

How they hunt and all about
the underwater behaviour

that we are not able to see
from the boat.

A tag has to be attached

to the orca in
exactly the right position.

MAN: Here it goes. Here it comes.

EVE: Oh, that's a good shot.

(LAUGHS)

It is the least invasive method.
It is suction cups.

So it is not a scratch
on the whale afterwards

which is something we really like.

While studying the orcas,

Eve noticed a worrying change
in their behaviour.

They had worked out
the easiest way to get a meal.

EVE: We have seen that
the orcas are waiting

for those fishing boats to drop the net.

It acts like a dinner bell

and then all the orcas
of the area gather.

Quite a lot of herring slip from the net

and this is exactly what
the orcas are looking for.

But this new tactic
is dangerous, as Eve has witnessed.

We were there to monitor
the behaviour of the orcas

scavenging around the nets.

And we realised that
one large adult male

was actually trapped inside the net.

When the fishermen
started to retrieve the net

the orca was obviously starting to panic

and trying to pull as much as he could.

This orca was really fighting
for his life.

Stringent rules require fishermen

to get permission
before they open their nets.

But that took time.

EVE: It was such a long process.

We thought that the whale
was going to die of exhaustion.

Thankfully, the fishermen
finally got the clearance

to release their net
freeing the exhausted orca.

It was a huge relief to see that
this orca made it until the end

and finally got back to his family.

With marine mammals
and humans competing so directly

accidents are inevitable.

Two days after tagging an orca,

it's released and Eve collects it.

This tag is full of secrets, you know,

because it has been on
the whale for several days

and will just reveal exactly
what the whales have been doing.

Pictures from the tag
reveal the hunting technique in detail.

They dive below the ball of fish

and then back flip.

The tail slap stuns the herring.

Eve can even work out
how many fish the orcas are taking.

EVE: They can kill up to 30 herring
with just one tail slap.

And then what is pretty amazing is

all the individuals of the group
share the dead herring.

And it's not just
the orcas feeding here...

Humpback whales
are also drawn to the feast.

They too are being tagged and monitored

giving fishery scientist Leif

a complete picture of
how much herring is being eaten.

The whales, they take
probably less than 1%.

The fishermen take less than 10%.

So the balance there is that
there is enough for everybody.

Given that we manage to stock
in sustainable

and a long term sustainable way.

But it's estimated that
almost a third of ocean fisheries

are being over exploited.

The remarkable recovery
of the herring here

demonstrates what can happen
if a fishery is carefully managed.

Our maltreatment of the seas
has many effects.

Some are predictable,

but there are others
that are rather more surprising.

Southeast Asia.

The coral reefs here are among
the richest on the planet.

Marine biologist Steve Simpson,

is discovering how important sound is

to the animals that live in these
bustling coral cities.

STEVE: We're only now just realising
by listening underwater

that the fish are making
all these sounds.

They use sound to attract a mate.

To try and scare away a predator.

You hear pops and grunts
and gurgles and snaps.

There's a whole language underwater

that we're only just starting
to get a handle on.

(MOANING)

(CHIRPING)

Using an advanced
multi directional hydrophone,

Steve is trying to make sense
of this extraordinary chorus

by working out who is making
which noise.

One fish is especially talkative.

(POPPING SOUND)

It's perhaps the reef's
most famous resident.

The clownfish.

While filming for the series,

we followed this particular family
of saddleback clownfish

as they search for a suitable place
to lay their eggs.

It's a noisy affair.

(POPPING SOUND)

STEVE: For clownfish sound
really is everything.

They spend all day
talking to each other.

You've got dominance and submission.

You've got all the others
calling to each other.

It seems that they also use sound

in protecting themselves from the many
predators that hunt around the reef.

Including coral trout.

Will this model trout
fool the clownfish?

They react almost immediately.

(THUMPING SOUNDS)

By mimicking a predator,

Steve manages to record their alarm
calls without putting them at risk.

STEVE: You can really hear the deeper
pulsing sound of the female

as she tries to scare
the coral trout away.

And all the little ones are
just popping... Pop, pop, pop.

As if to say, "I'm still okay.
I'm still alive."

(THUMPING SOUNDS)

So they've got this real language
of sounds that they're using

just to try and defend the colony
against this coral trout.

But that discovery
has led to a serious worry.

(MOTOR HUMMING)

STEVE: The fish were really
popping away at the predator.

But as soon as the boat came over
they looked completely distracted.

With all that noise it completely
changed how the fish were behaving.

Unable to make themselves
heard above the noise of boats,

the family can't warn each other
of danger.

And so they are now
vulnerable to attack.

You think about how many boats
are driving around.

All of the ships,
all of the offshore drilling.

All the noise that we're making
in the ocean

you realise just how much
we're drowning out

this natural biological noise,

robbing animals of their ability to be
able to talk to each other.

All this noise may have
serious consequences for many reef fish

because their babies, as soon as they
hatch are swept out to sea.

There they feed and grow
until strong enough to swim back.

And to find the reef, they use sound.

STEVE: They listen in. They eavesdrop
to the noises that they can hear

and they use that to choose which reef
they want to make their home.

But obviously because we're adding
all this noise to the ocean

it's a wonder whether they can even
hear the reef at all.

(HORN BLOWING)

Man-made noise is now
everywhere in the ocean.

And it has an effect on
marine creatures of all kinds.

From tiny fish

to gigantic whales.

But Steve believes there are solutions.

STEVE: Noise in the ocean
is a real problem.

But, it's something that we can control.

We can choose where we make the noise.

We can choose when we make the noise.

We can directly reduce
the amount of noise that we make

and we can start doing that today.

(MOTOR HUMMING)

We're only now beginning to realise

what an impact our noise is having
on the inhabitants of the ocean.

Other forms of pollution
are only too familiar.

Since its invention some
hundred years ago,

plastic has become an integral part
of our daily lives.

But every year,
some eight million tonnes of it

ends up in the ocean.

And there, it could be lethal.

While filming Blue Planet II,

the crews found plastic in every ocean.

Even in the most remote locations.

South Georgia.

900 miles north of Antarctica,

this isolated wilderness
is the breeding place

for vast numbers of penguins
and elephant seals.

(SNORTING)

(SQUAWKS)

(GROANING)

It's also a favourite nesting site

for the largest bird in the sky.

A wandering albatross.

(SQUAWKING)

Here we learn of
the extraordinary lengths

ancient parents go to give their chicks
the best chance of survival.

Each devoted parent travels thousands
of miles searching for fish and squid

to feed their hungry chick.

But despite all their efforts,

the albatross colony here is in trouble.

Lucy Quinn is part of
the British Antarctic Survey team

studying the birds here
for the last 40 years.

LUCY: Its only through looking at
long terms studies

that you get a sense of these creatures.

And the albatrosses here have,
over the past 10 years, been in decline.

There are a number of
possible reasons.

While foraging at sea,

albatross can get entangled
and drowned by fishing gear.

But Lucy is particularly alarmed

by what the parents are bringing back
for their chick.

LUCY: Albatrosses have
the ability to cough up

bits of food that they can't digest.

And from that we can tell
what they've been eating.

A healthy albatross chick in its diet
should really have things like squid.

So we can find the squid beaks
that come out of the pellet.

And also things like fish
so we can find fish bones as well.

But these chicks are being
fed something very different.

We have some plastic that
this poor chick has had to bring up.

Plastic bag.

Here we have some food packaging.
Looks like rice.

Luckily for this chick, he has managed
to get this out of his stomach.

So, fingers crossed he doesn't have
any more plastic left in there

before he fledges.

For other chicks, plastic can be fatal.

LUCY: Unfortunately,
there is a plastic toothpick

that have actually gone through
the stomach.

Something just as small as that has
actually has managed to kill the bird.

It's really sad to see.

Lucy collects and records
what plastic she finds around the nests.

LUCY: These are items that were
regurgitated just from last season.

And that's gonna be
a vast underestimation

because that's just ones
that we happen to find.

There'll be many more that
we never see being brought back.

To find out where
all this rubbish is coming from,

Lucy and her team have attached
GPS trackers to adult birds.

LUCY: It's showing where they're
going to find food for themselves

and to find food to bring back
for their chicks.

It really shows us that
they could be picking up plastic

from thousands of miles away.

Plastics coming from either being
dumped at sea

or also from people's homes.

Plastic gets into the rivers and then
the rivers flow into the sea.

So this isn't just a problem
around these remote parts.

This is happening worldwide.

And it's our rubbish
that's going into the oceans.

It's our problem that we need to solve.

In some parts of the ocean,

it's estimated that there are now over
one million pieces of plastic

for every square mile.

And we're only beginning to discover

just how seriously
that affects marine life.

On the east coast of the United States,

researchers are investigating
the mysterious deaths of young dolphins.

The team is led by Dr Leslie Hart.

It looks to be a young animal.

Maybe a little bit over a year.

So we're gonna try to find out more
information on why this dolphin died.

Looking at young dolphins...

The very young dolphins,
it's always heart-breaking.

Leslie takes tissue samples.

Their chemical analysis
could provide crucial evidence.

LUCY: We are often shocked
by the high levels of toxins

that we detect in these animals.

These young calves are dying
for a number of reasons.

But we suspect man-made toxins
are playing a large role.

And plastic could be
part of the problem.

Once in the ocean,

plastic breaks down into tiny fragments.

Micro plastics.

Along with all the industrial chemicals
that have drained into the ocean

these form a potentially toxic soup.

LESLIE: The really small organisms

can mistake these tiny,
tiny plastics as food.

Then the larger organisms
eat the plankton.

Then the larger fish
eat the smaller fish,

and so on and so forth.

Dolphins are
at the top of this food chain

and it's now thought that pollutants
may be building up in their tissues

to such a degree that a mother's
contaminated milk could kill her calf.

Industrial pollution
and the discarding of plastic waste

must be tackled for the sake of
all life in the ocean.

Around the world,
people are now devoting their lives

to saving some of the most
threatened sea creatures.

As here in the Caribbean.

Every year on just a few islands,

a remarkable event takes place.

As the sun sets,

giant reptiles begin to emerge.

(GRUNTS)

This magnificent creature preparing...

Whoops. (LAUGHS)

Preparing to lay her eggs

is the largest of all turtles.

A leatherback.

They can grow up to
half a tonne in weight.

And they have an ancestry that
goes back a hundred million years

to the age of the dinosaur.

But in recent times their numbers
have fallen catastrophically.

Here, however, in the Caribbean
there is hope.

(GRUNTS)

Leatherback turtles leave the sea

in order to lay their eggs
in the dry sand.

But out of water, these huge creatures
are easy targets for hunters.

In a small fishing village in Trinidad,

Len Peters has experienced this
first hand.

I grew up in a household where
the presence of turtle meat was normal.

The fridge was always full of it.

Everybody... Everybody harvested
turtles, including my parents.

It's only when I became
exposed to things

that were being published
about leatherbacks

who were on the verge of extinction.

And nobody cares.

That piqued my interest.

Len took the leatherback's
future into his own hands.

He began patrolling the beach at night
to protect the turtles.

A brave thing to do.

LEN: We were met with
tremendous resistance.

People would pelt us at night.

I have had persons insult me.

I've had persons curse me.

I've had persons physically
try to wrestle me with a machete.

So it was really
a hostile time back then.

If Len was going to
save these turtles

he needed to win over
the whole community.

LEN: We had to find a way to
get the villagers to benefit

from the presence of these animals.

He began to encourage
tourists to visit the beach

and trained some villagers
to be their guides.

To help secure the turtles' future,

he took the message
to the next generation.

Now what's... What's the largest size
a leatherback can grow to?

Uh, Shanie.

-2,000 pounds.
-That's correct.

Leatherbacks can grow to 2,000 pounds.

Well, that's a big turtle.

Len's hard work paid off.

And now, attitudes have changed.

(TALKING INDISTINCTLY)

LEN: It took us a while to
reach out to the villagers.

But gradually we got them
involved as well.

We got some of the poachers who
would be hunting the animals to

be part of the conservation programme.

As well as protecting
the adult turtles,

the team also collect any eggs
that might be flooded at high tide.

LEN: If the eggs are laid
too close to the sea,

we relocate the eggs and rebury them.

Thanks to the efforts of this community,

these turtles have had an extraordinary
change in fortune.

This is now thought to be
one of the densest

leatherback nesting beaches
in the world.

LEN: When we started at the height
of the nesting season,

the numbers will be 30-40 turtles
a night.

Now, it's over 500.

So, we have seen an increase
from 40 turtles

to 500 turtles a night
in just around 20 years.

Precious new hatchlings
are also given a helping hand.

Any that emerge during the day
are collected

to be released safely back to the sea,
away from hungry birds.

This little leatherback will have to
face a thousand hazards

before it returns as an adult
to this beach where it hatched.

And those dangers will be
greatly increased

because of damage that we have done
to the ocean.

Good luck, little leatherback.

Protecting breeding sites on beaches

may improve the fortune
of some marine animals,

but safeguarding them while they roam
the high seas is much more difficult.

Out here, there is little protection.

Every night, thousands of miles of
fishing lines laden with hooks are set.

There's enough, it's said,
to wrap twice around the world.

Nets large enough to engulf cathedrals

trap hundreds of tonnes of fish
at a time.

Long distance travellers such as sharks
are particularly at risk.

It's estimated that tens of millions
are killed every year,

including the biggest fish in the sea,
the whale shark.

Shark biologist Jonathan Green
is concerned

that time is running out
for these extraordinary creatures.

We know that they're being fished
possibly at a massive rate.

They may be taken by the thousands,
possibly tens of thousands a year.

If that is indeed true,

we don't know how long they can
withstand that kind of fishing pressure.

To save them,
Jonathan is trying to solve

the mystery of where they give birth.

And, for the first time, he has a clue
as to where this might be.

Pregnant whale sharks are thought to be
travelling from across the Pacific Ocean

to Darwin Island in the Galapagos.

Jonathan is going to try and attach

a multi-sensor camera tag
to a pregnant female.

Okay. We're good to go.

These sharks only stay in the area
for a few days.

This may be his only chance.

Jonathan has to attach the tag before
the shark dives to dangerous depths.

The tag will remain on the giant's fin
for two days

before it's automatically released.

Once retrieved, it reveals
some unusual behaviour.

Oh, beautiful, beautiful.

There's a silky rubbing up against
the front. Next to her right.

The silky sharks are
brushing up against her rough skin,

perhaps to scrape off parasites.

These predatory sharks make the surface
waters very unsafe places

for young fish of any kind.

There is a surprise in store.

The tag's depth sensor reveals
that she dived

to a depth of 600 metres.

But down there,
it's too dark for the camera.

The only way Jonathan can prove
if they're giving birth

is to go down and look.

(RADIO CHATTER)

(RADIO CHATTER)

Out of the gloom, a shape materialises.

Another massive whale shark.

Oh, look at her. She's having a look
at us. She's looking right at us.

She is huge.

And look at the belly.
Absolutely massive.

That's a large pregnant female.

She's turning around.
She's turning around.

Goes to show we can follow them.
We can follow them in the submarine.

She leads them down
into the darkness.

MAN (OVER RADIO): Rover control.
Passing 100 metres, descending.

Heading down.
I think she's accelerated slightly.

She's too fast.

And with the strong current running
against them, the sub can't keep up.

But, for the first time,
Jonathan can see for himself

exactly where she's headed.

What specifically Darwin
could provide

is a safe refuge for those new-born pups
where predators can't access.

Perfect conditions
for the formative years

of these ocean-travelling giants.

That was unbelievable.

(SIGHS) Dream of a lifetime.

His discovery
that pregnant whale sharks

are visiting this very deep patch
of the sea floor

is strong evidence that this is indeed
where the giants produce their young.

If I can actually prove
that they are giving birth in this area,

then we'll have
the information necessary

to go to governments and actually say,

"You must preserve those routes
that they're migrating through."

And then, and only then,
can we really truly afford protection

for this beautiful ocean traveller.

Today, less than one percent

of our international waters
are protected.

And the creation of marine reserves
is vital

if we're to safeguard the future
of many ocean creatures.

It will require
international cooperation.

But here, too, there is hope.

We can turn things around.

We've done so once before.

For centuries,
the sea-going nations of the world

hunted the great whales
until they were close to extinction.

And then, in 1986,
those nations got together

and agreed to put a stop
to commercial whaling.

Today, although a few nations
continue to hunt whales,

some of the great whales
are making a recovery.

In the tropical seas
surrounding Sri Lanka,

there are stories of vast gatherings
of whales.

When the civil war ended in 2009,

locals here were able once again
to fish these waters.

There were soon reports of assemblies
of sperm whales,

the likes of which had not been seen
for centuries.

Marine guide Daya was determined
to get to the truth

behind these fishermen's tales.

DAYA: The fishermen told me that
there are lots of whales

a little bit north from here.

They didn't actually tell me a number,

but in big numbers, not one or twos.

Er, many.

It took him three years,

but eventually, he found evidence
to support these rumours.

(SPEAKING LOCAL LANGUAGE)

(SPEAKING LOCAL LANGUAGE)

DAYA: We saw about 15 sperm whales
go past us.

Then, another four came past us.

After about 40 then passed me,
I started counting.

Still, they kept coming,
so I lost count.

I estimated that we saw about
300 sperm whales.

Sperm whales were once
killed in vast numbers

and it's thought that if the slaughter
had continued,

the species would be in danger
of extermination.

But now, here at least,
they are being seen in huge numbers.

DAYA: I believe they come here to feed,
mate, and raise their young.

So, this must be a holiday spot
for them, you know.

At the moment, I don't know
of any other place in the world

that, er, sperm whales gather like this.

Although some whale
populations are still in decline,

scenes like this prove that when
sea-going nations come together,

they can achieve astonishing results.

But today, the oceans face threats
on a truly global scale.

The Great Barrier Reef.

The largest coral reef system
in the world.

Here, we filmed stories which reveal
just how smart fish can be.

This ingenious tuskfish, for example,

used a favourite coral anvil
to smash open shellfish.

This astonishing behaviour
has been closely studied

by local scientist Alex Vail.

We're calling Percy
"Percy the Persistent"

because he took, like, an hour
to open the first shell.

He must have hit it well over 50 times,

but he just kept on going
and finally got it open.

Alex grew up
on the Great Barrier Reef

on one of its more remote islands,
Lizard.

He knows the reef intimately.

But, in 2016, while he was filming
for Blue Planet II,

Alex witnessed a catastrophe.

ALEX: When we started filming,
everything was pretty much fine.

All of the corals
were basically healthy.

But in the last few weeks,
everything changed.

I have never seen anything
like this before.

A combination of a warming ocean

and an unpredictable weather event
called El Niño

raised sea temperatures
to record levels.

And this had a disastrous effect
on the corals.

The heat causes reef-building corals
to lose their nourishing algae,

exposing their white skeletons.

When temperatures remain high,
bleached corals die off.

The bleaching this year has been
the worst in history

for the Great Barrier Reef.

About 90 percent of the branching corals

on the reef out here at Lizard Island
are dead.

It also has disastrous consequences

for the other creatures that live here.

ALEX: Percy swimming around out there.

The really sad thing is that his
castle's starting to bleach.

If we lose our coral, there's a chance
we're going to lose our tuskfish.

It's incredibly sad to see areas
that you've dived on

since you were a little kid
just turn to rubble.

I cried in my mask, when I saw,

you know, some of the devastation
from this bleaching.

In the last three years,

over two-thirds
of the world's coral reefs

are thought to have suffered from rises
in ocean temperatures.

This is not the only challenge
they face.

Research is revealing
how the fundamental

chemistry of the ocean is changing.

Professor Chris Langdon shows me
what this might mean

for the future of our seas
by pouring dilute acid over shells.

And how much more acidic is this
than the present ocean?

CHRIS: This is more concentrated than
the pH of the ocean

but it accelerates the process
so we can see something visually.

So, what's happening is, these shells,
they're made out of calcium carbonate,

and the acid is dissolving them.

And coral reefs are made out of
the same material as these shells here.

But surely this is not happening
in the ocean now. Right now?

What we're seeing here is more dramatic
than what's happening in the ocean.

But the shells and the reefs
are really truly dissolving.

Coral reefs could be gone by the end
of this century.

And the cause of this?
Carbon dioxide.

Dissolved in the sea water,
it forms carbonic acid.

The more carbon dioxide
in the atmosphere,

the more acidic the ocean becomes.

Evidence points to the burning
of fossil fuels

as the primary cause for these
increasing levels of carbon dioxide.

And this is man-made beyond question.

Beyond question.

But Chris believes all is not lost.

All we have to do, and I say all,
is reduce our CO2 emissions.

We can switch to renewable fuels,
wind and solar,

instead of natural fossil fuels.

And so, none of this has to

-develop to the worst case.
-And that could fix it?

Yeah, absolutely. So, this future does
not have to play out. It's up to us.

(THUNDER RUMBLING)

As the climate changes,
the seas warm.

Our oceans are being seriously affected.

And this is nowhere more apparent
than at the poles.

Antarctica.

For the Blue Planet II team, this was
their most ambitious expedition.

For the first time in history,
a manned submersible

will try to dive to a depth
of 1,000 metres

and reach the Antarctic seabed.

A true journey into the unknown.

(RADIO CHATTER)

(RADIO CHATTER)

MAN: Control rover. Passing 40 metres.
Over.

(INDISTINCT SPEECH)

Leading the team
on this historic dive

is deep sea scientist John Copley.

We get our first glimpse
of this landscape.

And the carpet of life around us
is astounding.

It's beautiful.

Diving in a submersible
gives John an entirely new understanding

of how this rich ecosystem works.

But it also offers him
a unique opportunity

to investigate how the ocean here
is changing.

While we're observing the marine life
down there,

the subs are also recording
what the environment is like,

so we're getting measurements
of temperature, of salinity.

It's hopefully gonna enable us
to understand the changes

that are happening in this vital part
of our planet.

To get a fuller picture,
John also lowers

a deep sea temperature probe.

His data is contributing
to an international attempt

to chart the rise in both sea
and air temperatures.

What shocks me about
what all the data show

is how fast things are changing here.

We're headed into uncharted territory.

To truly comprehend

the effect of the temperature
increases here,

John takes to the skies.

From here, he can record
the number and size

of the icebergs being produced
as the ice shelves melt and break apart.

The bergs we're seeing all around us
give you some idea

of how huge this process is
that's taking place on the Antarctic.

As the floating shelves
break up, they allow water,

which has been locked up on land as ice
for thousands of years,

to empty into the sea.

And this is predicted to push up
sea levels.

If the ice shelves break up,
then that opens the flood gates.

Ice on land flows faster into the sea

and that's what pushes up
the sea levels.

So, what's happening here right now
affects all of us.

Already, cities like Miami here
are under threat.

Scientists predict that by the end
of the century,

the sea levels could have risen
by a metre or even two.

Were that to happen, parts of this city
would certainly be submerged.

Around the world, hundreds of millions
of people live near the coast,

and as sea levels rise,
their lives will be seriously affected.

It's now clear that our actions
are having a significant impact

on the world's oceans.

During the four years it took
to make this series,

we've witnessed many of these changes
first-hand.

But we've also worked alongside
men and women

dedicating their lives to safeguarding
the ocean's future.

LUCY: The oceans provide us with oxygen,

they regulate temperature,

they provide us with food
and energy supplies.

And it's unthinkable to have a world
without a healthy ocean.

CHRIS: I still think we have
the capability

to change the manner in which
we're wasting resources,

in which we're poisoning our oceans,

and we can look to a future
with healthy oceans.

LEN: When I look forward, I believe
that if what we are doing

can be duplicated just a little bit.

These animals will have a chance
of surviving.

JOHN: It comes down, I think, to us each
taking responsibility

for the personal choices that we make
in our everyday lives.

That's all any of us can be expected
to do.

And it is those everyday choices
that add up.

We are at a unique stage in our history.

Never before have we had
such an awareness

of what we are doing to the planet.

And never before have we had the power
to do something about that.

Surely, we have a responsibility
to care for our blue planet.

The future of humanity,

and indeed all life on Earth,

now depends on us.

(THEME MUSIC PLAYING)