Original subtitles

Over one third of our planet is frozen. And yet the icy

worlds of the Arctic and Antarctic are as alien to most of

us as the surface of another planet.

They are places of superlatives, from ice caps that hold

nearly 80% of our planet's fresh water to frozen forests

that encircle the entire globe.

These are places that feed our imaginations, places that

seem to be borrowed from fairy tales. They are dominated and

shaped by the ice, both by its coming and by its going.

This is our planet's last true wilderness, and one that is

changing just as we're beginning to understand it. In this

series, we'll be travelling to all parts of these lonely

lands, both north and south, to witness its wonders, perhaps

for the last time, and to discover some extraordinary

examples of survival against all the odds, as can be found

anywhere on the planet.

The poles are permanently capped with ice. Nowhere

is colder, windier or more hostile to life.

I'm standing at the North Pole, the very top of the Earth.

Up here, it's easy to see why the polar regions are so cold.

The sun never rises high enough in the sky to warm my

back, and those rays that do strike the surface are mostly

reflected back from this great whiteness. But the

fundamental problem is that there's no sun here at all for

half the year. The polar winter is unrivaled in its

harshness, a night that lasts for months. Only the toughest

day, as temperatures plunge to minus 70 degrees centigrade.

And yet, the greatest challenge to life here is not the

cold, but the extreme swings between the seasons. When the

sun finally returns, an extraordinary transformation begins.

This frozen world begins to melt away.

The polar spring brings a brief opportunity for life.

By summer, the sun no longer sets and works its magic for 24 hours a day.

Now it's a race to breed before the sun departs.

By autumn, all but the hardiest abandon the poles and the ice extends its grip.

Land and sea close down for the long polar winter until, once again, the sun returns.

It's spring in the high Arctic, and the sun illuminates

a giant frozen ocean, the first stop on our journey.

The most powerful land predator is on the prowl.

A male polar bear is searching for a mate.

Willing females are few and far between, and the sea

ice on which he travels will soon melt and vanish.

He's running out of time to find a mate in this vast frozen desert.

Ten miles ahead, a single female without cubs. Exactly what the male is seeking.

He seems to relish her scent even though she's

miles away. This is an exciting prospect.

She's clearly giving off the right signals.

He locks onto her tracks, eager not to lose her trail. It's

easier to tread in the compacted snow of her footprints.

This pursuit could last for days.

The female eventually comes into view. The search is finally over.

For the female, only half his weight, this must be a nerve

-wracking encounter. The male could kill her if he chooses.

But he has other intentions, and she is ready and willing.

She leads him to higher ground.

It seems that courting polar bears prefer privacy, often

leaving the sea ice and heading for the hills to avoid the

prying eyes of rival males who might disturb them.

Few have witnessed this moment. For the male, his

only tender encounter in an otherwise solitary life.

But it doesn't last long. A rival suitor has also caught the female's scent.

Courtship has to be put on hold. He must fight for his rights.

He sees off this first challenger without injury

to either party. But bloodier battles are to come.

Another battle won. Though he has been slightly injured. He

hurries back to his mate, but now she seems to have lost her

enthusiasm. Female polar bears are high maintenance.

Wherever she goes, he will follow, mating with

her when she allows and guarding her at all times.

Over the next two weeks, the male sees off many

rivals, but the battles take their toll on him.

He is almost spent, but he has ensured that no other bears have mated with his female.

It's time for the couple to go their separate ways. She will

give birth to his cubs alone in nine months time, and he may

never see her again. He returns to the frozen ocean, no

doubt relieved to resume his solitary ways. And just in

time, the ice beneath his feet will soon be gone.

Each spring, the Arctic Ocean undergoes an extraordinary

transformation. An area of sea ice the size of Europe melts,

exposing the rich waters beneath.

Short-tailed shearwaters have travelled 10,000 miles from Australia to be here.

18 million visitors darken the skies, the

largest gathering of seabirds on the planet.

Humpback whales have come all the way from the

equator to feed in these rich polar waters.

Their giant tails are five metres across.

Simply raising them above the surface gives the whales

enough downward momentum to reach the great swarms of Trill

and Herring below.

The shearwaters follow the giant's lead.

For those who can get here in summer, these waters provide

a feast of epic proportions. But the good times will be very

short, a problem that faces all life in the polar regions.

Journey south across the Arctic Ocean, the first land you

reach is Greenland, the largest island in the world. Despite

its name, Greenland is mostly white, covered by a giant

ice sheet six times the size of the United Kingdom.

In the middle of the island, the ice is nearly

two miles thick. It's a bleak, quiet world.

Sapphire blue melt lakes are the first sign that a dynamic process is underway.

Each lake forms in a matter of days, expanding

until it's miles across and starts to overflow.

The spill water then carves its way through the ice.

The water courses through an icy delta like blood along

the arteries of a cold-blooded monster. A monster that is

stirring.

And without warning, the water suddenly plunges down an open

shaft, falling a vertical mile into the heart of the ice

sheet.

This melt water has a surprising effect. It lubricates the

junction between the ice and the rock floor beneath, so the

entire ice sheet is now on the move, sliding downhill into the ocean.

This, Jakobshaven Isbre, is the fastest flowing glacier

on our planet, moving as much as 40 meters a day.

As it advances, it destroys everything in its path, even

cutting its way through Greenland's great mountain ranges on

its drive downwards towards the sea.

When speeded up, these solid rivers of ice seem to flow just like liquid rivers.

This is the titanic force that cuts down

mountains and levels the surface of continents.

The ice is now entering the last stage of its descent. As

it gains speed, huge crevasses open that extend down to its

very core.

It's reached the ocean, and millions of tons of

ice have lost the support of their rocky bed.

Something must give.

These ice falls are an ominous sign of what is

about to happen. A rupture deep within the glacier.

A colossal iceberg is born.

This single block of ice, many hundreds of meters

across, would dwarf the biggest of mankind's buildings.

Every year, tens of thousands of icebergs are spawned

by Greenland's glaciers, and their number is steadily

increasing as the climate continues to warm.

The break-up of the bergs fills the bays of the Arctic with

exquisite ice sculptures. It also releases great volumes of

cold, fresh water into the sea. Greenland's meltwater

influences the course of the ocean currents, which in turn

has an effect on the weather around the world.

The Arctic is closer to home than many of us realize. It

includes the northernmost parts of the three continents on

which most of us live, Europe, Asia, and North America. The

first bare land we reach on our journey south is a bleak,

treeless wilderness known as Tundra.

Each spring, animals travel up from the south to be ready

for the rich grazing that will be unveiled by the spring

melt. For the caribou, the timing is critical. Arrive early,

and a winter storm could kill you. Delay too long, and you

may fail to lay down the fat needed to survive a polar winter.

For the south still and stooped shrouded

figures end the flat monotony of the Tundra.

This is the tree line, the first place on our journey with

sufficient warmth and liquid water to enable a tree to grow.

Surviving here is so crushingly difficult that it can take

hundreds of years for a seedling to grow into a stunted

shrub.

But even small trees can provide cover for a predator.

Wolves. These in northern Canada are the largest and most

powerful in the world, and they're setting out to hunt.

The pack is 25 strong, a sign that the prey they're seeking is formidable.

These bison are even bigger than their southern cousins and

the largest land animals in North America. For generations,

wolves and bison here have been shaped by their battles with

each other, making each the most impressive of its kind. The

bison will not stay long among the trees. They're not safe here.

The wolves are closing in, but their chance of ambushing

the bison in the woods has passed. Their prey are now in the

open and grouped together for safety.

The wolves will need to work as a team if they're to make a kill.

They circle the herd, try to unsettle it and split it up.

But the bison are armed and dangerous. They will be safe as

long as they stick together.

The wolves up their game, harrying the herd, a ploy to

trigger a stampede and split away one of the smaller ones.

The bison form a defensive circle around their young, horns pointing outwards.

The wolves need a bison to break rank.

But the tables are turning, and now the wolves have to retreat.

The pack focus their attention on the rear of the herd, and the bison begin to panic.

A young bison falls behind.

Even this yearling dwarfs the wolves.

Running, the young bison rushes to the herd. Looking

head down, the herd's only thought is escape.

A stroke of luck for the wolves.

The kill will feed the pack for several days, but then they

will have to resume the chase. At the frozen ends of our

planet, the struggle for survival never eases.

South of the tree line, the winters are shorter, so trees

grow faster and taller, and forests begin to appear. As the

warm, humid air from the south meets the cold arctic air,

the moisture it carries crystallizes, and snowflakes fall.

They fall from the sky.

Each crystal forms around a particle of dust.

All have a six-fold symmetry, but no two have

ever been found with exactly the same shape.

Their variety and complexity is breathtaking.

Each snowflake is water waiting to be released in spring.

For this reason, snow is the lifeblood of these silent

forests, and all that live here depend on it in one way or another.

Some,

like the great gray owl, appear in spring for

the boom times, then vanish like phantoms.

Others, like their lemming prey, are here year-round

beneath the snow, insulated from the cold air above.

The northern forests are a crossroads for seasonal visitors

and arctic specialists. But they are so much more than this.

Together, they make up the taiga, an unbroken belt of forest

that stretches 7,000 miles around our planet and contains

one-third of all the trees on Earth.

The taiga forest marks the end of our journey through the

Arctic, from the frozen ocean down across the lands that

surround it.

The other end of our planet, the Antarctic, is starkly

different, a frozen continent completely surrounded by

ocean.

Icebergs here are so large that they're measured in miles,

not meters. They're the only obstacles in the path of giant

waves which circle around the continent unchecked by other lands.

These seas may be cold and storm-wracked, but they're bursting with life.

No bird is more at home in water, and they are masterful surfers.

Penguins are found only in the southern hemisphere. They

can't fly, but they don't need to. There are no polar bears

here.

These are gentoo penguins. Each spring, they come ashore

to lay their eggs and rear their young. Their hungry chicks

demand so much seafood that both parents have to go fishing.

And fishing can be dangerous.

A southern sea lion.

It uses the speed of a breaking wave to catch up with the gentoos.

Sea lions normally eat fish, so he's used to catching

streamlined swimmers. But the gentoo seem more than his

match out at sea. He must change tactics.

Perhaps it will be easier in the shallows.

But no, it seems penguins are uncatchable in water.

How about on land? The penguin's wings, so powerful for

swimming, are of no help when it comes to running. Now,

surely, the sea lion has a chance.

But on the beach, both are like fish out of water.

Every summer, over 40 million penguins take to the southern ocean to feed.

They're joined by thousands of whales. Minkies are the most

numerous. They all come here to harvest the richest ocean on

earth. Carrying on south, we get our first glimpse of the frozen continent.

Southern humpbacks, after traveling 4,000 miles from

the equator, are finally arriving in Antarctica.

Humans have long felt the lure of this mysterious world,

yet it was only a hundred years ago that the first explorers

walked inland and were confronted by the

highest, driest, and coldest territory on earth.

Every year, the continent is transformed as the

sea ice that surrounds it begins to disappear.

This melt halves the size of Antarctica. It's the most

spectacular seasonal change occurring anywhere on our

planet.

The remnants of the sea ice are occupied by

sunbathing seals that have been here all winter.

But new arrivals are following the retreating

ice edge, and they have come here to hunt.

Killer whales, the ocean's top predator. Killers are

like wolves, for they will hunt animals far larger than

themselves. But even smaller prey are a problem if you can't reach them.

The solution is teamwork.

Swimming in perfect formation, they flick their tails

in unison and create a wave that cranks the ice.

They regroup and assess the damage. A more powerful wave is needed.

The ice flow is breaking up. Now they're close enough to get

a good look at their target. The seal is a crab eater, sharp

-toothed and feisty. Not their favorite.

The wolves of the sea move on in search of easier quarry.

A whittle seal, that's better. These are more docile and easier to tackle.

The pod stays close together and travels silently.

This time, they unleash a far more powerful wave, and with astonishing accuracy.

These big waves are not intended to break the ice, but

to knock the prey into the water. And they rarely fail.

The seal is now where the killers want it. But the hunt

is far from over. They need to grab their prey by the tail

while avoiding its snapping jaws. Only then

will they be able to pull it down and drown it.

Side swipes create violent underwater turbulence, a new tactic.

Blowing bubbles gives cover for others to lunge at the seal's tail.

Somehow the seal manages to reach a tiny ice floe.

The killers could easily grab it, but now this seems to

become a game. The seal's life hangs on a roll of the ice.

Yet again, the pod joins forces to dislodge the seal.

The seal sees a chance to escape.

Exhausted, it no longer has the energy to pull

itself to safety. And the killers are moving in.

Game over.

Although such team hunts are rarely seen, scientists believe

they may be the most complex ever documented in the natural

world. They were first witnessed by Captain Scott and his

men when they came to explore Antarctica 100 years ago.

Journeying further south, the fragmenting ice is replaced

by a permanent sheet that doesn't melt even at the height of

summer. It's a barrier that many creatures find impossible.

It repels even powerful minke whales. They have to turn back

if they can no longer reach the air they need to breathe.

Under the ice, life has to be extremely specialized to

survive. Few of us will ever experience this strangely still

world. And as yet, no one knows much about it.

The crystalline surface of the ice stalactites provides

a home for ice fish whose bodies are full of antifreeze.

The ceiling of ice shields those living below it from the

violent polar weather that rages above. Little here has

changed for millions of years.

The cold allows animals to grow very slowly and become giants.

The relative of the woodlouse is the size of a dinner plate.

And this so-called sea spider has legs that span half a

meter.

Now, explorers are revealing other worlds that lie hidden beneath the ice on land.

These smoking towers are the gateway to a network of caves.

Each contains an extraordinary assembly of ice crystals unlike any other on earth.

Like snowflakes, every crystal is unique.

Some are taller than a man.

Others are thought to harbor life seeded by strange bacteria

that thrive in these extreme conditions. The breeze that

gently sways these crystals is responsible for making them.

It's steam from the molten heart of Mount Erebus, the most

southerly volcano on our planet.

It's now thought that the ice caves fringing this crater

may even be a home for hitherto unknown life forms.

From this oasis of warmth at the edge of the continent, our

journey continues inland to the far east. We head towards

the South Pole. The first great hurdle is the

formidable trans-Antarctic mountain range.

We're following the route taken by Scott and Amundsen as

they struggle to become the first humans to reach the South

Pole.

They were traveling on foot, and their first sight of these

mountains must have been daunting indeed. In front of them

stretched one of the world's longest ranges, spanning

2,000 miles from one side of the continent to the other.

The winds up here are the fastest on earth. They reach speeds of 200 miles an hour.

An ice-capped mountain bears the scars of the

gales, bizarre sculptures carved from solid ice.

It's not only the ice that yields. This sculptured spire

is the remnant of a mountain eroded from all sides by the

ferocious elements.

Beyond, a wholly unexpected landscape, the dry valleys.

Only 1% of Antarctica is free of ice, and most of that bare rock is here.

The dry valleys are more like the surface of Mars than is any other place on earth.

The floor is covered with extraordinary natural sculptures,

created by the same winds that help to keep these valleys

free of snow.

Over time, entire boulders are weathered from

the inside out until just a shell remains.

At the head of these valleys, ice is making a breakthrough.

Millions of tons are tumbling in slow motion into the valley.

These ice blocks are the size of skyscrapers.

And this is the Beardmoor glacier, which

Scott and his men somehow traversed on foot.

It's over 100 miles long and one of the largest glaciers on earth.

But nothing could have prepared those early

explorers for what they were about to encounter.

The Antarctic ice cap, the largest expanse of ice on the

planet. It's three miles thick in places and imprisons 70%

of the world's fresh water.

From here to the South Pole, 700 miles away, there is nothing but ice.

I'm at the South Pole at the end of my journey. Although

it's mid-summer, the temperature here is a bone-chilling 35

degrees below freezing. It's exactly 100 years, almost the

day, that the first human being saw ice. I stood right here,

Amundsen followed by Scott. In those days, reaching the

poles was regarded as the ultimate in human endeavor and

endurance and a source of great national pride. Today, the

polar regions have a rather different significance because

now we've come to understand that what happens here and in

the North affects every one of us, no matter where we live

on this planet.

The greatest challenge for the team-making frozen planet

was the extreme remoteness of their locations. Many of the

shoots lasted months at a time and needed a number of crews to join forces.

One location that would require such siege tactics was

Mount Erebus, Antarctica's most active volcano. This magical

mountain does not give up her secrets easily.

To capture the full story of Mount Erebus from

top to bottom required four different film crews.

The cave team has dropped off at 12,000 feet close to the crater.

In howling winds and thin oxygen, their challenge is to find

a way into the volcano itself. They are venturing into the

unknown. Somewhere below are spectacular ice caves melted

out by volcanic steam. Getting the team safely underground

is a relief for director Chad and Hunter. Excellent, it's a

lot warmer down here. It's freezing up there, minus 29. With

him is cameraman Gavin Thurston. You sort of forget being in

here. You are actually inside a volcano. You know, above us,

there's, and below us, there's bubbling lava. And you've got

all these gases seeping up through here, which is how these

caves are made. So there's also increased carbon dioxide in

here. As the cave team head deeper, dangerous volcanic gases

made breathing difficult. The clock is ticking. They

will not have long to find the caves of crystals.

Above ground, the aerial team is pushing for the summit of

Erebus. Series producer Vanessa Berlowitz directs from the

front seat, while aerial cameraman Michael Kellum controls

the camera attached to the nose. We're going to be around 14

,000 feet. We're going to be at the performance limits of

this aircraft. Any bad weather comes in up there, you're

pretty much screwed really. You've got to get off the

mountain fast. Above 10,000 feet, the pilot must breathe

oxygen through a plastic tube in his nostrils. Approaching

the crater, conditions do not look good. Today, Erebus is

belching out steam and gases, making flying extremely risky.

Up here, the air is so thin, the helicopter can't hover and

must keep moving. This is aerial filming at its

most extreme. They struggle to get a clear view.

We're just coming up to 14,000 feet. You can actually look right into the lava lake.

That's looking really good, Mike. Just hold that there. The

cameraman captures a rare shot of the molten lava, but it's

soon obscured again.

The volcano is temperamental. The team have seized a rare

opportunity to see into its molten heart. But now they must

descend to safety. As the weather closes in

above, the cave team are making progress below.

It's Christmas Day, and the crew are dressed for the occasion.

Just watch my back on these icicles. I don't want to snap that top one off.

Right, how strong are these pillars of ice, Matt? How big

a round is it? It's about that round, about five. Really

strong. So if I squeeze past, it's not going to snap

it. Gavin is reassured by advice from the scientist.

I'm sorry. It's terrible. Oh, look. You

know, it fits perfectly, look. Look at that.

Fortunately, these crystals are made of frozen water and

can grow back in weeks. Got these beautiful clear glass-like

pillars. And right next to it, this really

delicate, look how thin that filament is there.

As the cave team explore deeper, each chamber reveals

ice crystals more strange and spectacular than the last.

No one on the team imagined a single Antarctic

mountain could house so many wonders.

Down at the foot of Mount Erebus, a third crew, the dive

team, plan to explore the volcano's lower slopes, which

extend beneath the frozen sea. On board is underwater

cameraman Hugh Miller. The problem is we don't actually know

what's under the ice here, so who knows? It's a bit of an

adventure. Old-fashioned tools still work best. First, a

hand chisel to create an opening, then a saw to widen the

hole. Ice diving in the coldest waters on the planet should

be taken extremely seriously. This dive's going to be a lot

of things. Warm is not on that list. Insulated suits will

keep them alive under the ice for only 60 minutes. Once

the helicopter departs, there's no margin for error.

The dive team begin to explore the lower slopes of

Erebus, discovering a hidden world rarely seen by humans.

Patrolling the icy shores of the volcano are killer whales,

the most southerly in the world. Trekking them from above is

the orca team.

They need a helicopter to get ahead of the

whales and to land them on the fragile sea ice.

Cameraman Jamie McPherson must pick his spot carefully. His

aim is to get the cameras as close to the killer whales as

possible without disturbing them.

He uses a film camera to capture the action in slow motion.

And the orcas come right by him. Even in the extreme cold,

a film camera proves to be rugged and reliable, provided

there's enough film in the camera.

End of the rock. No!

I got him coming out, I just didn't get him going back in.

Below the sea ice, the dive team is setting up an underwater

studio. Using a range of waterproof lights and time-lapse

cameras, they hope to capture the growth of bizarre underwater ice formations.

Over the coming weeks, the dive team would go below the ice

over 100 times to film the extraordinary secret world on the

lower flanks of Mount Erebus. On top of the ice, the orca

team has repositioned. Their new goal is to get underwater

shots of the whales. They don't dare to get in the water

with orcas because they're afraid of them. With orcas,

attaching a camera to a pole is a safer option,

provided the whales aren't put off by it.

No one is prepared for what happens next.

The entire pod arrives.

Riddle it.

Eyeball to eyeball, this is about as close to killer

whales as it's possible to get. By using multiple crews and

cameras, the frozen planet team have been able to capture

the full Erebus story, from the fire at its crater down to

the whales that patrol its frozen shores. It's quite

a privilege to feel a whale breath on your face.