All language subtitles for frozen4

At the far south of our planet

lies the most hostile
of the Earth's frozen lands.

Antarctica.

Here, temperatures can fall

to below minus 80 degrees Celsius...

...and winds blow up to 200mph.

Its icy centre
is almost devoid of life.

But on the edge of Antarctica,

some creatures find a way

not just to survive,
but to flourish.

Here are some of the greatest
concentrations of life

to be found anywhere on Earth.

The continent of Antarctica

lies at the southern end
of the globe.

Twice the size of Australia,

it's the largest, coldest
expanse of land on the planet.

To the north of it, however,

across 1,000 miles of ocean,

lie the subantarctic islands,

where conditions are
somewhat less hostile to life.

The largest of them
is South Georgia.

Here, a million king penguins
live and breed the year round.

A mother has returned
after a month at sea...

...collecting food
for her hungry chick.

At ten months old, chicks are
the size of a human toddler,

and covered in no more
than a downy fleece.

Until they get
their waterproof feathers,

they themselves cannot go to sea...

...so they have to rely totally
on their parents

to bring them food.

Their time together is brief -

just long enough to disgorge
her crop of fish and squid.

All too soon,

parents have to return to sea
to collect more.

But getting back there

can take several hours.

Hundreds of parents
make the commute together.

A beak can be used as an ice-pick

to negotiate the steeper parts
of their trek.

This mile-long snow-covered trudge

is unique to this colony,

and has never been seen before.

At last, the sea.

After several days on land,

their feathers need washing
to be ready

for the long days of swimming
that lie ahead.

But this is a dangerous place
to loiter.

Leopard seals.

Three metres long,

more than three times
the size of a king penguin,

these fearsome hunters
are usually solitary.

But at this time of the year,

in this bay, there are
as many as 30 of them.

If these penguins think
that they're safe on land...

...they are mistaken.

Any one of these huge seals

can take as many
as ten penguins a day.

Their best chance...

...is to stay with the crowd.

There's safety in numbers.

Made it.

Only to return in a month's time...

...and once again face death head-on.

This is surely
one of the greatest challenges

faced by any parent.

1,500 miles off the continent's
east coast

lies another of the tiny outposts

that are vital for the survival
of Antarctic wildlife.

The Sub-Antarctic Islands
of the Antipodes.

In spring, the longer days
turn each tiny speck of land

into a potential breeding ground...

...for the Antipodean
wandering albatross.

Its wings are three metres across,

amongst the biggest of any bird.

This 14-year-old male

is now mature enough
to start selecting a partner.

For the smaller, darker female,

choosing a suitable mate
is of equal importance.

After all,

they may stay together
for the next 50 years.

To make this crucial decision,

they use one of the most
elaborate courtship rituals

of any sea bird.

He begins by sky-pointing.

It seems to be working.

Next, he attempts a move...

...known as the double head-bob.

The finale is the real decider.

Synchronised wing-spreading.

She seems impressed.

But another male appears...

...and shows off...

...his wings.

The greater the span,

the more attractive he could be.

But the first male won't tolerate

a rival cutting in.

Yet another hopeful
joins in the competition.

And another.

This was not supposed to be
a dance-off.

She prefers one tango at a time.

It seems that this is not
going to be his year after all.

But he's caught the eye
of another albatross.

Once again, he begins
his courtship display.

But this is, in fact,
another male.

Regardless, he continues
to demonstrate his eligibility.

This could still be the one

with whom he will share
the rest of his life.

On the Antipodes Islands, it's
becoming increasingly common.

Today, there are three times
as many males as females.

Females feed further north
than the males,

in waters used
by industrial fishing fleets

that catch and drown
great numbers of sea birds.

As a result,
the female albatross here

is now declining fast.

A same-sex partnership like this

may bring no survival advantage...

...but is apparently preferable
to a life alone.

The wealth of life found around
Antarctica's lonely islands

is evidence of the richness of
the waters that surround them.

The Southern Ocean.

It may appear treacherous.

Its gale-force winds certainly
create powerful currents.

But all this stirring
has an important effect.

It brings up nutrients
from the depths,

helping to create some
of the richest seas on Earth.

And this provides food
for the largest animal

to have ever lived.

The Antarctic blue whale.

It's more than 30 metres long...

...but it's rarely
been filmed before.

Only the Southern Ocean

can provide the four tonnes of food

that the biggest of all
blue whales needs every day.

This ocean giant was
almost hunted to extinction,

but thanks to an international ban

on commercial whaling,

its numbers are now increasing.

The closer the seas are
to mainland Antarctica...

...the colder they become...

...until, a few hundred miles
offshore,

the ocean's surface freezes solid.

It forms a cover of sea ice

that is twice the size of Europe

and encircles the entire continent.

This is a stronghold

for one of Antarctica's
most remarkable inhabitants.

It uses its teeth

to prevent its breathing holes
from freezing over.

The Weddell seal.

The most southerly breeding
mammal on the planet.

This ten-day-old pup

is still entirely dependent
on his mother.

Out on the ice,

it may be safe
from marine predators...

...but within its first two weeks,

it will have to venture
into the underwater world

upon which its future depends.

This is the coldest water on Earth.

So it's not surprising

that a pup needs some encouragement.

It's time to leave the safety
of the breathing hole.

To catch fish
and then safely return,

this pup must learn
how to find his way

through the maze
of underwater ice caverns.

But after just eight minutes...

...his mother signals
that it's time to head back.

She can hold her breath
for an hour and a half.

But he is already starting to tire

and is running out of air.

On their way back
to their breathing hole,

they hear a sound
as loud as a fighter jet.

It is the call of a half-tonne
male Weddell seal

announcing that
he's on the lookout for a mate.

She, however, is still
producing milk for her pup,

and so isn't sexually receptive.

But he doesn't stop trying.

To repel his advances,

she leaves her pup's side.

But the pup isn't strong enough

to haul himself out
without his mother's help.

She tries to fight off
the adult male.

She's wounded him so seriously

that he is unlikely
to be back any time soon.

A gentle nudge from Mother

is all an exhausted pup needs

to make it to the safety
of the sea ice.

Mothers stay with their pups
for six weeks,

by which time they're strong
enough to fend for themselves.

As spring arrives,
the sea ice retreats,

and in a few places,
Antarctica's coast

is exposed to the open sea.

And that attracts
all kinds of animals.

Having spent the winter at sea,

chinstrap penguins can now
come ashore to breed.

Soon, the coast becomes
extremely crowded.

But there are ways
to maintain social distance.

Oh, dear.

The chicks,
until they're eight weeks old,

depend on their parents for food

and, critically, warmth.

Meltwater is a particular problem.

The chicks' feathers
are not yet waterproof.

Getting wet could be fatal.

A father's duty is to keep
his chicks high and dry...

...using the only
building material available.

Stones.

And suitable ones are precious.

So it's vital to hold on
to every one.

But while backs are turned...

...collections are readily
plundered by neighbours.

With thieves like these around...

...that stone has just become
even more valuable.

What's lacking in skill...

...is made up for with persistence.

But a parent's labours
could be in vain.

Summer temperatures
have now been recorded

as high as 18 degrees Celsius.

As a result, the penguins'
carefully constructed platforms

are now being flooded.

There is more meltwater
than ever before...

...and the ground
is becoming a quagmire.

Downy feathers,

which are excellent insulation
from the cold when dry,

are no defence when wet.

Hypothermia sets in.

Over the last 50 years,

the number of chinstraps here
has dropped by half.

Antarctica is losing

the very element that defines it.

Ice.

That is now diminishing

six times faster than it once did.

Neumayer Glacier on South Georgia

has lost nearly six miles
of ice in just 20 years.

Parts of Antarctica are warming
faster than anywhere else

in the southern hemisphere.

And that is having
a serious effect

on the animals
that live on its coast,

such as the Weddell seal.

With less sea ice available,

many are now hauling out on land.

That's not just a problem
for them...

...but also for the predators

that specialise in hunting them...

...one particular group
of Antarctic killer whales,

100 or so animals strong.

Killer whales are among
the most intelligent

of all nonhuman predators.

And they're now working out
how to tackle prey

that isn't a Weddell seal.

An Adelie penguin,
resting on the ice.

A mere snack
for an adult killer whale...

...but it gives this group
of six-year-olds

a chance to practise one
of their particularly ingenious

hunting techniques.

Wave-washing.

A skill that takes
at least 15 years to perfect.

First, the killer whales assess
the size and position

of a possible victim.

They must then calculate
the speed needed...

...for an attack.

But they're too late.

Even though a co-ordinated
flick of their tails

creates a reasonable wave...

...it's nothing
without precision timing.

With fewer of their favourite
prey of Weddell seals

resting on ice floes,

killer whales now have no choice

but to target new prey.

Crabeater seals.

Numbering 15 million,

they're the most abundant
marine mammal on Earth.

But they are a far more
dangerous target...

...than a Weddell seal.

Stronger...

...and more inclined to fight back.

But each member of this pod

needs to eat a seal a day.

So the pressure is on to feed.

They're led by a matriarch

who knows exactly what to do.

Living 100 years or more,

she has plenty of hunting
experience to draw upon.

With the ice floe
having broken in two,

the seals have become
more vulnerable.

The matriarch now pushes
the ice floe into open water

to give their next wave
maximum impact.

This requires teamwork
and precision.

She makes her final calculations.

This seal has only one way

of escaping death.

Unlike the less muscular
Weddell seal,

the crabeater has the strength

to hurl itself out of the water...

...just in time.

For the killer whales,

it has been
a significant waste of energy.

Their need to eat
is now greater than ever.

A leopard seal.

By far the most ferocious
of all Antarctica's seals.

Dare this pod tackle him?

He's a three-metre adult,

an aggressive hunter
in his own right.

Unused to being targeted
by killer whales...

...the leopard seal
makes the mistake

of leaving the safety
of the ice floe.

The killer whales approach
the seal with utmost caution.

Keeping away
from its powerful teeth,

they seize it by its tail...

...and try to drown it.

The hungry youngsters
get to feed first.

But tackling less-familiar prey
is risky,

and starvation is a real
danger for these killer whales.

Only time will tell

whether these skilful hunters
can adjust quickly enough

to survive in this changing world.

Beyond Antarctica's
rich coastal fringes

lies a vast frozen interior.

This is certainly one
of the most inhospitable places

for life on Earth.

Its icecap,
three miles thick in places,

holds almost two-thirds
of the Earth's fresh water.

The accumulation of snowfalls
over millions of years

has bedded vast mountain ranges
longer than the Himalayas.

All that can be seen of them
is the tips of their peaks.

Smoking vents standing
20 metres tall

hint at the volcanicity that
lies beneath the ice sheet.

The recent discovery

of more than 20 previously
unknown volcanoes

reveals that Antarctica is

one of the most volcanic
places on Earth.

Almost 4,000 metres high,

Mount Erebus is one of just
seven volcanoes on Earth

with a permanent lava lake.

Less than 1%
of this frozen interior

is free of ice.

But isolated outcrops of rock

offer sanctuaries
for one of the few animals

willing to brave temperatures
of minus 30 degrees Celsius.

The snow petrel.

They fly 100 miles inland

in order to breed
away from predators.

This male gets to work
clearing a shallow scrape,

which he will then line
with feathers

to give his chick
a little protection

from the bitter cold.

But crevices are in short supply...

...and rivals are ever ready
to fight for them.

When aerial combat fails,

snow petrels deploy
another weapon.

Vomit.

It could be lethal.

If the putrid stomach oil freezes,

his flight feathers
could stick together.

Fortunately, he knows
how to clean them...

...with a snow bath.

Now to get on with
the task of breeding.

From here to the South Pole,
1,000 miles further inland...

...conditions become
even more hostile for life.

Winds driving over
the East Antarctic Ice Sheet

can reach speeds of up to 200mph.

As these gale-force winds
descend from the ice sheet,

they pick up both speed and warmth.

They create the most arid
conditions on Earth.

These aren't snowdrifts.

They're sand dunes.

Some of these so-called dry valleys

have not felt rain
in over a million years.

Carved by the wind,

strange monuments
up to four metres tall

stand on the desolate valley floor.

The only life form...

...a mummified crab eater seal

that mysteriously strayed here,

possibly thousands of years ago.

But if you look hard enough...

...life can be found
in Antarctica's interior.

Hidden in the mountains
of eastern Antarctica,

Lake Untersee.

A little over ten years ago,

scientists dived
beneath its frozen surface...

...and made a discovery that
would change our perception

of the possibility of alien life.

Lying on its lakebed

are living structures
found nowhere else on Earth.

Giant stromatolites.

Standing half a metre tall...

...their existence down here

provides an extraordinary insight

into how life on our planet
might have evolved.

These living structures
have been built

over thousands of years

by arguably the most important
microorganism on Earth.

Cyanobacteria.

The very first living organisms
to have produced oxygen.

Without them, Earth would
have remained uninhabitable

for higher life forms.

If the building blocks for life
can be found here,

in the most hostile
place on Earth...

...surely life could exist

in the ice-covered lakes
of distant planets.

Whilst filming in the extremes

of Antarctica, capturing
the remarkable behaviour

of wave-washing killer
whales was to prove

the crew's greatest challenge yet.

The team set off
from the Falkland Islands

on board the Golden Fleece,

which will be their home
for the next month and a half.

It's under the command

of Antarctic explorer Dion Poncet.

What's the weather like
for the crossing?

The first day is good.

And then...

...nothing bad...
that we can see...yet...

To reach Antarctica, they must
first cross the Drake Passage -

650 miles of
the world's roughest ocean.

Confined to his bunk, executive
producer Mark Brownlow

has yet to find his sea legs.

Destroyed.

Fourth day at sea.

Sick.

On arrival at the peninsula,

their search begins,
guided by Leigh Hickmott,

a whale scientist who
is part of a 14-year study

on the only killer whales
in the world

known to wave-wash.

We now have
a greater understanding,

perhaps, of how small
the population is, actually,

of these killer whales.

The parent population
is about 50 animals,

so really not very many at all.

With so few of these highly
specialised killer whales

patrolling an area more than
half the size of Wales,

they head to where
they were last sighted.

After three days of
round-the-clock surveillance,

the team finally catch a glimpse.

Found our first killer whales.

There's the one we want! Whoo!

Good start.

To get shots low to the water,

they launch a gyro-stabilised
camera system in a small boat

that's only half the length
of the killer whales.

Stay still.

That's so cool!

Definitely feel like
we've just been checked out.

It's quite intimidating.

In a filming first,

camera operator Bertie Gregory

launches the drone
to capture a new perspective

on this hunting technique.

We've got four, five
killer whales, spy-hopping.

Some are moving away!
They might get ready for a wave.

There's the first wave!

That's the breaking wave
that's broken the pack in half.

The seal's in the water!

Seal's in the water!
He could be in trouble here.

They could just
kill the seal cleanly,

but they are using the seal
to teach their young how to hunt.

It's really hard to watch.

The team's ground-breaking footage

is also providing
valuable scientific data,

contributing to the long-term study

of these highly specialised
killer whales.

Animal B-17 - she was first
photographed back in 2009.

So here she is.

This is a photograph taken
during Frozen Planet I.

If we look on the right,

here's a picture that
we took during our cruise.

She's certainly the matriarch
of her particular group.

We're seeing how
she's teaching her offspring

to become this
very efficient killer.

But after such a promising start,

conditions take a turn
for the worse.

The thing that's changed

enormously here is the weather.

In the past,
the peninsula was famous for

perfect calm, still,

bright sunshine, clear skies.

And...

...doesn't happen so much.

And warmer weather here means
less sea ice, which could

have consequences
for the killer whales'

preferred prey of Weddell seals.

There's a cruel irony, really,

that we've today found the largest
group of Weddell seals,

but they're on the beach.
They're not on pack ice.

And that's potentially because
the Antarctic Peninsula

is one of the most rapidly
warming places on the planet.

The team film the killer whales

switching to hunt crab eater seals...

...but then, something
remarkable happens.

They approach one of Antarctica's

most formidable predators,
the leopard seal.

This is absolutely incredible,

because that's really not considered
a key prey for them.

Ooh, he's chosen a bad piece.

The ice has split into four...

...and he's chosen
the smallest quarter.

It's phenomenal.

It's the first time a killer whale

hunting a leopard seal
has been captured on camera.

As extraordinary as that is,

it's a sobering indication
of the challenges ahead

for these killer whales.

I don't think
it's too much to say

that we are facing
a climate emergency.

There's a real chance that,

as we lose this pack-ice
environment,

that this predator, that has
one of the most complex

foraging strategies on the planet,

is going to be potentially lost.

And that's a tragedy that I,

in my lifetime,
don't want to see,

and for our children,
most certainly,

we can't allow to happen.

Next time, we journey to
the frozen lands of the north.

A world of snowbound forests
and vast open tundra.

Where seasonal extremes

push animals to their limit.

The Open University
has produced a poster

exploring how animals adapt to life
in the world's coldest environments.

To order your free copy,
please call 0300 303 0553,

or go to bbc.co.uk/frozenplanet2

...and follow the links
to the Open University.