Original subtitles

In winter, at the top of the planet, lies an icy wilderness,

not of land, but of frozen water, the Arctic Ocean.

Its surface forms an almost solid platform that

is bigger than the whole of the United States.

Its presence and condition dominates the lives of all the

many and varied animals that live both on it and beneath it.

In the coming months, the Sun's warmth will

melt much and expose the rich waters beneath.

To survive here, life must adapt to this

world that alternates between ice and water.

After three months of winter darkness, the Sun rises across Arctic Norway.

A newly-emerged polar bear mother encourages her cubs

to take their first tentative steps on the sea ice.

Cubs will stay with their mothers for two years,

learning the skills needed to survive out here.

But thereafter, they will be on their own.

Further out on the sea ice, this young female bear

less than six years old is already fully independent.

She's superbly adapted to life on the frozen ocean,

protected from the cold by thick insulating fat and a double

layer of fur.

This time of year is the best time for feeding.

The ringed seals on which she depends feed on fish and are

swimming 40 meters beneath her. But after 10 minutes down

there, they must return to the few gaps in the ice to take a breath and rest.

She has acute hearing and one of the most sensitive noses in nature.

She can detect the layer beneath two meters of snow and ice.

Timing is everything.

Only one in ten attempts is successful. So for a young bear,

each meal is very important. But a male has picked up the

scent of the kill.

Large males pose a real threat

and could inflict fatal injuries in a fight.

But she stands her ground.

Remarkably, rather than fight, they start to play.

And then they set off to explore together.

Well fed and still young, these two seem to be forming a friendship.

She shows off the swimming skills that enable

her to move with ease between water and ice.

She's behind you.

Dancing on ice.

Apparently, just for the joy of it.

After three hours together, they part company.

And return once again to their solitary lives.

Polar bears thrive at this time of year, thanks to

the huge platform of sea ice on which they can hunt.

The Arctic Ocean lies across the top of the Northern

Hemisphere and over the North Pole itself and is surrounded

by three continents, Europe, North America and Asia.

In winter, the sea ice extends across an area of over five million square miles.

But off the coast of Arctic Russia, a tiny pocket of water has been kept open.

By the continuous stirring of 30 trapped beluga whales.

These four meter long Arctic whales are superbly

adapted for hunting far beneath the surface of

the to breathe every 15 minutes or so.

But this cold spell is exceptionally severe. And

there's not another breathing hole within 20 miles.

Nearby fish and squid disappeared long ago. These emaciated

whales have been imprisoned by the ice for five months and

they're now starving.

Their only chance of escape will come when there is a change in the season.

As spring finally reaches the north of the

planet, air temperatures creep above freezing.

The impenetrable ice ceiling begins to fracture.

Small, life-saving channels open up.

Bringing freedom.

But spring is a dangerous time for beluga. As tides and

currents pull ice apart, the beluga find themselves in a

labyrinth of ice. A labyrinth of shifting ice floes that

could close their breathing holes at any point and so drown

them.

Using their sophisticated sonar, they try to find a way through the icy maze.

And eventually reach a patch of open water.

They're not the only whales here.

Narwhal, the unicorns of the sea, are closely related to beluga.

In a rarely seen encounter, these two kinds of whales

appear to socialize. Who knows what's going on between them?

But soon they set off together through these shifting fields of ice.

A journey of up to one thousand miles.

Before they reach ice-free waters, where they can rear their young.

As the spring sunshine strengthens, the broken pack

ice off the coast of Greenland becomes a nursery.

A harp seal pup. Born just a week ago.

He has little fat. His thick fur is his only protection from the arctic chill.

In between doses, he waits for his mother to return.

She has only one pup a year.

And will produce milk for only 12 days. One of the shortest nursing periods in nature.

That is just long enough for him to develop a thick layer

of blubber. Thanks to his mother's milk, which is 50% fat.

And his mother stays alongside, while he learns

an important survival skill for any seal.

How to swim.

He may not be keen to take the plunge. The salt

water is minus two degrees Celsius after all.

Pups start with a doggy paddle.

Mum stays reassuringly close.

Still developing his insulating blubber, a pup is at

risk of hypothermia. So needs to rest and warm up.

Each day, he puts on another two kilos.

And practices swimming for just a little longer.

Since birth, this pup has tripled in weight. And

he's now at ease in this curious other world.

12 days gone by. A mother's work is done.

In producing milk, she's lost a third of her body weight.

Now she must return to her feeding grounds.

She will never see her pup again.

The next four weeks, he spends alone, sticking close to the ice platform.

Surviving on his fat reserves, as his downy fleece

is replaced by a sleek coat more suited to swimming.

But temperatures in the Arctic are now rising faster than ever before,

creating storms that break up the ice floes earlier each spring.

Harp seal pups are being tipped into freezing waters

before they're ready to endure long periods at sea.

In some pumping areas, almost none survive.

As spring turns to summer, life on the sea ice suddenly begins to proliferate.

The daylight increases and algae that had remained

dormant within the ice all winter begin to bloom.

This upside-down meadow is now cropped by plankton.

For a little skeleton shrimp living at the bottom of a

towering forest of kelp, the best way to get a share of the

food is to climb.

If you're only two centimeters long, this is like scaling a skyscraper.

And yet, it's not alone.

Hundreds of fellow shrimps are attempting the same ascent.

A new mother has parked her brood halfway up, and she's not about to give way.

This one is a determined commuter, but the mother's

drive to protect her young is now causing a traffic jam.

At last, many have made it to the topmost branches of this underwater forest.

And it's been well worth the effort.

The prize is a plankton feast.

Raining down from above.

By midsummer, arctic waters are filled with food,

making them into one of the richest of all oceans.

Feeding billions of microscopic mouths, as well as the biggest mouth on the planet.

The bowhead whale.

Its four-meter-long baleen plates enable it to sieve out up

to six tons of plankton a day. And it grows swiftly into an

18-meter, 100-ton giant.

In summer, the bowheads are so well fed, they head for an annual get-together.

After a year of wear and tear, their skin needs reconditioning.

This is a whale health spa.

Rocks and sand in the shallows are used like pumice

stones, with which to rub off dead skin and parasites.

Such places can become very popular.

This bay off the coast of Russia attracts an immense gathering of over 50 bowheads.

They are the longest-lived of all mammals.

Some are 200 years old and have been coming here for many decades.

Suddenly, their peace is shattered.

Killer whales have arrived from the south.

Nine meters long, weighing nine tons, and renowned for their

exceptional intelligence, this particular pack specializes

in hunting bowhead whales.

The bowheads retreat into the shallows, where it

will be harder for killer whales to launch an attack.

But the killers can swim much faster than the bowheads.

The group tries to close ranks,

but the killers attempt to separate them.

They look for individual signs of weakness.

In the shallows, the bowheads lash out with their seven -meter-wide tails.

But in the confusion, some run aground.

Others try to reach deeper water.

This youngster, half the size of an adult, is extremely vulnerable.

The killer whales take turns to ram into its sides,

cracking its ribs so that it struggles to breathe.

Then they push the youngster down until, finally, it drowns.

The battle is over. It lasted an hour. Yet now, the killer

whales eat only one part of their prey, the young bowhead's

soft, fatty tongue.

Today, more and more bowheads are falling prey to killer

whales, as the warming climate causes the protected barrier

of sea ice to melt earlier each year.

By midsummer, millions of migratory seabirds, having flown

thousands of miles to get here, are feeding in the Arctic's

rich waters.

Over a million crested auklets, no bigger than puffins, now

descend on Alaska's St. Lawrence Island and are preparing to

breed.

To win a mate, a male must try to stand out from the crowd.

And auditions are already underway. Males and females,

unusually, look very similar, each adorned with an elvish

-like crest. But it's the size of the crest that matters.

And this male's headgear seemed to be no more than adequate.

A position on the ground is also important.

One large male wants this particular perch.

And having got it, he breaks into song.

He now releases a potent tangerine scent from

the back of his neck, and a mob of fans go wild.

This male, however, seems to have nothing to offer.

But a gaggle of groupies can be a dangerous distraction.

An arctic fox.

It's found an egg.

With the stage cleared, the highest perch has become vacant.

This is a moment to shine.

His display doesn't go unnoticed.

And his tangerine perfume attracts an admirer.

And not just one.

Now it's down to the females to impress him.

In Auckland society, both sexes have a say when it comes to choosing a mate.

At the height of summer, with 24 hours of

sunlight a day, over half the sea ice melts away.

The beaches of Stalbard provide safe places to

haul out for one of the arctic's special residents.

Walruses.

They forage for shellfish for up to 17 hours at a stretch.

Now it's time for a rest.

Each adult male weighs more than a ton.

And heaving oneself over the sand, without the support of water, is very hard work.

This male has a particular sunbathing spot in mind.

Right in the middle of the 50-strong huddle.

The prod helps in parting the crowd.

Almost in.

At last he can settle down for a snooze, swaddled

on all sides by the bodies of his neighbours.

But it's not a peaceful spot.

Sleep isn't easy when a fidgety bedfellow decides that

he has an itch that needs scratching. This is the time to

moult, to get rid of one's old fur with all its

parasites, and expose the healthy new coat beneath.

These days, Stalbard's summer temperatures can soar to 22 degrees celsius.

Flushing red by bringing blood close to the skin helps them to keep cool.

But some overheating is unavoidable, especially for a big male.

Enough is enough.

Getting up here was a slog. But this male has found a

better way of getting down. Let gravity do the work.

Now that is cool.

Everyone is doing it. It saves both time and energy.

But walruses will need all the tricks they can find.

The Arctic is warming, and these cold-loving

animals are facing a precarious future.

For millennia, the Arctic Ocean has frozen over in the

winter, and then gradually melted throughout the spring and

summer. But in the last 40 years, the extent

of the summer sea ice has declined by 50%.

Some predict that it will be ice-free as early as 2035.

This profound change is already having an impact

on the Arctic Ocean's highly specialized wildlife.

With less summer sea ice from which to hunt seals, some

polar bears are now travelling up to 400 miles, swimming

continuously for up to 10 days in search of land.

Wrangell Island off Arctic Russia, the only land for almost 100 miles.

Each summer, more and more polar bears come ashore here.

This newly arrived mother needs to find food for her family,

but knows not to approach other adult bears.

A full-grown male can kill an eater cub, and will do so if

other food is in short supply. There are over 1,000 bears on

this one island.

It's the greatest concentration of polar bears on the planet.

And there is food to be had on these remote shores.

A walrus colony. 2,000 strong.

The walruses panic.

And there are casualties.

Fights break out.

This is no place for a young family.

The mother calls her cubs away.

They must search elsewhere.

Grass is a poor meal for a growing cub. And starvation in summer is a real threat.

But this opportunity to feed is one she cannot afford to ignore.

It's time to gamble.

Her cubs follow her. She urges them to stay back.

The males are twice her size, but preoccupied

with feeding, they tolerate her presence.

The distress calls of her cubs, however, attract unwelcome attention.

Their mother rushes to shield them with her body.

But she seems torn between guarding her family and feeding herself.

Cubs left by themselves are easy prey for a hungry male bear.

But now her maternal instincts take over.

Faced with a mother's fury, the dominant male backs down.

Having fought her way in, her cubs can now feed for the first time in weeks.

Polar bears were once the supreme hunters on the sea ice.

Now, each summer, more and more of them have to come to land

in search of food.

Whether the ice bear survives into the next century

depends on what happens to the sea ice on which they rely.

As with all of the Arctic Ocean's remarkable wildlife, it's

how the climate changes over the coming years that will

determine their future.

In today's unpredictable and changing Arctic,

filming its wildlife is an ever-increasing challenge.

None more so than trying to capture the brief time that a

mother harp seal spends preparing her pup for life at sea.

To find the seal's pupping grounds, the crew have sailed to

a remote area of the Arctic off the east coast of Greenland.

But here, they quickly discover that its usually solid

platform of sea ice has broken up into thousands of flows.

It's a surprising sight, even for veteran captain Bjorn Caverno.

And with the sea ice so fractured, there's no sign of any wildlife.

With mother and pup together for just 12 days, it's a race

to find the dense pack ice on which the breeding seals give

birth.

The team head a further 100 miles off the Greenland

coast to an area no film crew has ventured into before.

Their gamble pays off.

From the smaller, more maneuverable tender, cameraman Jamie

McPherson hopes to record the precious time mother and pup

spend together on the ice.

With mum now calling it into the water, this pup may be

ready for its very first swim. It's the cue for underwater

cameraman Hugh Miller. We're going to try something

different and actually get into the water with the seals.

We're definitely in new territory here. To film this rare

moment underwater, Hugh will need to get a lot closer

without disturbing them. But with Arctic waters at minus

2 degrees Celsius, even with a protective thermal drysuit,

Hugh only has an hour before he risks developing hypothermia.

It's now a matter of waiting for the pup to take the plunge.

The guys have now been in for about 20 minutes. I can

guarantee you they'll be freezing cold. Hugh's

body temperature is getting dangerously low.

Conditions have been really hard. The cold has been very,

very difficult. With less than a week to go before this

mother is likely to leave her pup forever, Jamie

continues to capture their intimate interactions.

While Hugh is yet to film a single shot. To make matters

worse, temperatures fall to minus 30 degrees centigrade. And

as the wind direction changes, the flows are forced closer

together. That guys has just come in from all around us. It

could flip the boat and that would be the end of the shoot.

Hemmed in by blocks weighing several tons, the small skiffs

are at risk of getting crushed. They radio for help, but as

the mothership approaches, she shunts even more ice their

way.

We've got these big chunks of ice either side of us and they've got to go somewhere.

With help three days away, the crew can't afford any mistakes.

In the nick of time, a lifeline.

Safety of all. That was a bit of a lot.

By the next day, the pack ice has drifted apart. And not a moment too soon.

With the pup finally in the water, Hugh seizes his time.

But what will the pup make of this curious sea creature?

And this pup is fleeing with fleeing with the camera. I can

see Hugh's smile from here. Oh, lovely. Wow. That was great.

So nice.

Just as Hugh gets his reward, the arctic conditions take a

turn for the worse. We're getting some amazing stuff, but

now the wind's picked up, so we're trying to get out. With

the storm brewing, not even the mothership is safe among the

ice floes. The crew have no choice but to leave the scenes behind.

It would roll in on a storm. In the wind it would roll in

the water. And they drown? Yes, yes. They are not able to

survive themselves. It's terrible to see. Today, the

combination of reduced arctic sea ice and heavy storms is

leading to more and more tragedies like this.

Unless this trend is reversed, the future for much

of the arctic's unique wildlife hangs in the balance.

Thank you for watching.