The polar regions are more hostile to life than any other part of the Earth.
Human beings have little natural protection against the cold,
so why, for thousands of years,
have we endured the hardships that come from living here?
And what keeps us coming back today,
to the farthest extremes of our planet?
Winter in the most northerly town on Earth, Longyearbyen.
Here, for three months of the year, the sun never rises.
Only the full moon, which never sets as far north as this,
sheds any light into the darkness.
This town was built here in Svalbard,
only 700 miles from the North Pole, to support a mine.
The Arctic is rich in coal, oil and minerals.
In Siberia, the Russian Arctic, the mineral wealth has given rise to large cities.
This is Norilsk, the coldest city on Earth.
Temperatures regularly drop to below minus 50 degrees Centigrade.
Fuel freezes in the tanks of the trucks, and has to be melted in a rather alarming way.
Ships are frozen into the rivers for nine months of the year.
The ice must be cut away from their hulls
because steel becomes brittle and vulnerable to the thickening ice.
Like all Arctic cities, Norilsk depends on a power plant which heats everybody's home.
Waste heat from the plant even keeps a lake ice-free all winter.
Even at air temperatures of minus 50, the Norilsk Walrus Club come here every day.
There is evidence that a dip in cold water is good for the immune system,
but when the water is a degree above freezing,
it's hard to imagine that the benefits could outweigh the pain.
Today's Arctic city dwellers can lead an almost normal existence thanks to technology.
But towns and cities are very recent arrivals in the polar landscape.
The polar regions are the least populated part of our planet.
Most of the Arctic remains empty of human beings.
In the north, the Pole itself is covered by a freezing ocean.
Around it lie vast lands, of which Siberia is the largest and coldest.
Human beings first ventured onto the great plains of Siberia,
the tundra, thousands of years ago, and some live here still.
The Dolgan are one of the few tribes who still live in much the same way
as those first Arctic pioneers.
They are reindeer people.
Reindeer are one of few animals that can endure these bitterly cold conditions,
scraping a living by nibbling tiny plants that survive beneath the snow.
Nobody has ever totally tamed reindeer,
but today's animals are docile enough to allow the Dolgan
to drive them across the tundra in an everlasting search for their food.
This is a typical Dolgan village, home to just two extended families.
Here, in the coldest part of Arctic, the only way to get water
for nine months of the year is to melt ice from the frozen rivers.
At least there's no problem preventing food from decay.
Outside is one big deep-freeze.
Survival is only possible because of reindeer fur.
It makes wonderfully warm clothing,
though small children still have to be sewn into their clothes to prevent instant frostbite.
The Dolgan even use reindeer fur to insulate their huts.
This is living at its most communal.
Good relations with the in-laws are essential.
Reindeer are so valuable that the people only eat them if they have no other choice.
Their favourite food is raw fish from the frozen rivers.
Every week or so, these families have to travel to find new feeding grounds for their herds.
First, they round up their strongest animals with lassoes,
a skill that their ancestors brought with them when they came north from Central Asia.
And then, literally, they move house.
A whole Dolgan village can move on in just a few hours.
Over the year, they travel hundreds of miles like this across the vast tundra.
It was the herds of reindeer, wandering over the lands of the Arctic,
that brought the first Dolgan here.
Other people, however, took on an even greater challenge.
They left the land and looked for their food out on the frozen sea.
Here in the shifting world of the sea ice, they found sea mammals.
Pasha leads a group of Inuit men in Chukotka, the North Eastern corner of Russia.
The men have travelled many hours from home in the bitter cold,
fighting their way through a dangerous maze.
These hundred tonne ice floes could crush their small boats like eggshells.
The men have big families, and this is the only way they have of feeding them.
Pasha is looking for the puffs of steamy air produced by their quarry.
An animal that is bigger than many Arctic whales.
A two tonne seal with formidable tusks.
A walrus.
It's heading for open water. They must reach it before it dives.
An angry walrus could easily overturn the boats.
The harpoon sticks firmly in the walrus's thick layer of blubber,
and floats attached to it prevent the animal from diving.
Pasha wants to kill quickly with a single clean shot.
The hunters are exhausted after a long day, but they still have a lot more work to do.
This enormous prize will feed everyone's family for weeks.
It will take many hours to butcher. Nothing will go to waste.
The meat is parcelled up in bags made of the animal's skin.
It's midnight, but the sun is still up.
Summer is almost here.
This far north, the seasons change fast,
the sun is rising higher and growing warmer with each passing day.
The transformation from winter to summer is so dramatic
that it dominates the lives of all who live here.
The ice around the coast has almost disappeared,
and gone are the seals and walrus that Pasha and his men relied on.
They set off on another search for food.
Their destination is an island in the bay.
Their walrus skin boat is an ancient design,
light enough to carry high up the beach so it doesn't drift away.
THEY SPEAK RUSSIAN
Once again, the men will have to work as a team,
but one of them will be taking very serious risks.
The lightest man in the group, Kolya, is also the oldest.
He will trust his life to a length of old nylon rope and the strength of his friends.
These 100 metre high cliffs are home to thousands of guillemots,
and Kolya is after their eggs.
He relies on the men above to lower him to the right place.
Kolya is tough but his stress is obvious.
HE SHOUTS IN RUSSIAN
The men lower Kolya down to the bottom of the cliff,
and from there, he works his way back up the crumbling rock face.
Stop!
This mission will produce no more than about 50 eggs,
but at least there's no need to carry a packed lunch.
Over the years, many men have fallen to their deaths collecting seabird eggs.
This is truly dangerous work.
These Arctic peoples can't grow crops.
The frozen ground never thaws to allow them to do so.
They rely on animals for their food so the chance to collect a few
dozen eggs has to be taken, even if it means risking your life.
The change of season has transformed the Arctic's coastline
and inland, the difference is just as extreme.
July temperatures on the tundra can be surprisingly high, over 30 degrees centigrade.
Reindeer now move not just to find fresh pasture,
but also to avoid the summer swarms of blood sucking flies.
To keep their animals healthy, the local herders are driving them to the sea.
The cooler conditions on the coast bring relief to the herds
and the chance, every year, for different tribes to meet.
Pasha and his hunters live close by. They've had word of the herders' arrival.
The hunters' cargo is highly prized for the winter ahead,
fat-rich walrus meat that's been fermenting in the skin bags for two months.
Today will see an exchange that has taken place every summer for centuries.
The herders barter reindeer skins for walrus meat.
Pooling their resources has helped these communities to survive for so long.
A fry-up of guillemot eggs is all the better when shared with old friends.
Summer brings a brief chance for isolated peoples to meet.
This is an opportunity to exchange news, arrange weddings,
and tell the latest jokes.
HE SPEAKS RUSSIAN
By August, the summer is over.
Winter arrives only too swiftly, but the peoples of the Arctic,
who came here originally to hunt, have devised ways to deal with
the hostile and changing conditions that have stood the test of time.
Today, there's a new draw to the Arctic.
This is Greenland, a territory of Denmark now known to be rich in oil and precious metals.
This sled team is part of the Danish Special Forces.
They're on one of the world's toughest journeys, a 2,000 mile patrol
to maintain Denmark's claim to this valuable wilderness.
But the patrol's mission is only possible with the help of man's oldest Arctic companion.
Rasmus and Roland have spent the summer months training
and getting to know their team of Greenland huskies.
They need to have a very close bond with every single dog.
This is Roger and Armstrong,
actually the oldest dog in the whole patrol, but he's still going strong.
The men are totally dependent on the stamina of their dogs,
which will keep on running all through the bitter cold of the winter.
This is the last time the team will see the sun for two months.
The most intelligent dogs always lead,
choosing the safest route, feeling for hidden crevasses and thin ice.
This is one of six teams that patrol the whole of northeast Greenland,
the only people in an empty wilderness that is larger than France and Great Britain combined.
Conditions here are too extreme for current mining technology,
but some day, ways will be found of digging out the huge mineral treasures
that lie hidden within these mountains.
The patrol secures Denmark's claim to do so simply by being here.
But it's not the prospect of getting rich that makes men sign up for this patrol,
it's the chance for the journey of a lifetime.
The team travel over the ice for six months, covering up to 40 miles in a day.
Friendship and teamwork are essential if they're to succeed.
Their dogs can sleep outside no matter how cold it gets.
Rasmus and Roland have a nice cosy tent.
They have a few modern conveniences, including a radio,
with which they report their position back to headquarters in Denmark
and catch up on the latest news.
Right now it's the section of money,
what's new in the economy in Denmark, the financial crisis
and all the other things that we actually don't care about out here.
If you can cope with the conditions, then winter in the Arctic can be magical,
especially when the greatest light show on Earth is overhead.
The first humans in the Arctic believed the Northern Lights,
or aurora borealis, were dancing spirits.
Now we know the lights are caused by electrically charged particles streaming from the sun,
attracted by the magnetic pull of the earth's poles.
A big aurora storm contains enough energy to knock out satellite
communications and power supplies across the northern hemisphere,
so understanding the aurora is vital.
In Alaska, rockets are used to study the Lights.
A hundred miles up, at the edge of outer space, the rockets
release a cloud of glowing smoke that's visible from earth.
The smoke is blown by fierce winds which are generated by the aurora.
Mapping the movement of the smoke helps scientists to understand
how this unearthly spectacle affects our atmosphere.
They constantly monitor the aurora to help protect us
from its effects, so the rest of us can simply enjoy the magic,
just as the Arctic's first people must have done, thousands of years ago.
For all the many peoples of the Arctic,
the aurora is a reminder of the sun's presence throughout the dark days of winter.
But when the sun is below the horizon in the north,
it's above it at the southern end of our planet.
Here, humanity's history has been very different.
Antarctica is far colder than the Arctic,
and 99% of its land is permanently blanketed by ice.
Antarctica is so utterly remote
and inhospitable that no people ever settled here.
It was only 200 years ago that the first human beings
even glimpsed the vast continent.
The first people who crossed the Southern Ocean did
so for the same reason that the first people went to the Arctic Ocean,
to hunt sea mammals.
The populations of whales and seals are only now beginning to
recover from 150 years of intensive hunting.
But none of those hunters ever tried to venture into the frigid interior of the Antarctic continent.
The first successful attempt to do that was made only a hundred years ago.
This hut was the base for one of the most famous expeditions in polar history.
It was from here in 1911 that Captain Scott and his team
launched their attempt to be the first people to reach the South Pole.
The cold, dry conditions have preserved the interior
of the hut almost exactly as the expedition members left it.
Expedition photographer Herbert Ponting captured the spirit of the age of exploration.
These first explorers borrowed the techniques of the Arctic peoples.
They wore fur gloves and boots and burned seal blubber to keep warm.
They built sleds based on a traditional Inuit design.
They even made their sleeping bags from reindeer hide.
Scott and his men sought the glory of discovery in an untouched wilderness,
and died in the attempt.
But he, and those who followed him, were the first to reveal
the splendour of Antarctica to the rest of the world.
The lure of adventure still draws intrepid travellers today.
Like the first explorers,
most modern visitors come during the brief summer when the cold relents
enough for the toughest icebreakers to reach the edge of the continent,
but most still need a helicopter to go further.
The scenery in Antarctica is magnificent and dramatic,
but what really attracts people here is the wildlife.
An emperor penguin colony is a particular highlight.
Because human beings didn't arrive in the Antarctic until the past few centuries,
the animals have never developed a fear of man.
But very strict regulations govern how close people can approach any wildlife.
And when visitors leave, they must take every trace of their visit away with them.
Since 1959, the whole of Antarctica has been protected by international treaty.
The nations of the world have agreed that no country can claim Antarctica,
or prospect for its oil or minerals.
The only significant human activities allowed here are those that
extend our scientific knowledge.
But unlocking Antarctica's secrets requires some unusual tools.
This brand new robot submarine has been designed to go
far beyond the limits of any human.
Today, this diver is putting the sub through its paces on one of its very first dives.
It's designed to be small and nimble enough
to explore the Antarctic seabed without damaging it.
The submarine's mission, as it journeys into the unknown,
is to map the seafloor and look for species new to science.
The seawater here is a degree below zero, so even the toughest human diver can't stay down for long.
The submarine will explore deeper under the ice than anyone has gone before.
From the depths of the ocean to the highest peaks of the land,
new discoveries are being made even in places which were first visited over a century ago.
Mount Erebus was an irresistible draw to the legendary explorer Ernest Shackleton.
In 1908, his men became the first to climb this active volcano.
They soon discovered that this is the coldest place on the Antarctic coast.
Today's explorers still have to guard against frostbite in the height of summer
when temperatures rarely creep above minus 30 degrees centigrade.
Shackleton's men had no idea of the extraordinary spectacle
that lay beneath their feet.
Yep, OK, up on the wall there somewhere now. Yeah.
Under the ice and snow is a network of caves,
which only a handful of expert cavers have ever dared to enter.
This is the first scientific expedition to explore them in detail.
Here, there are ice formations that occur nowhere else on Earth.
Each cave contains its own unique collection of structures.
The team is mapping the caves to see how their shape changes over the years.
OK, flat side to here.
That's 126.8 degrees for the angle.
126.8. Correct.
The steam leaking from vents in the side of the volcano
is constantly sculpting this labyrinth that extends deep under the ice.
When the hot breath of the volcano hits the icy walls,
the moisture in the air freezes into beautiful shapes.
Some of the crystals are so unusual that the cavers are investigating
a remote but tantalising possibility about their formation.
Could it be that some of these extraordinary crystal shapes
are formed by highly specialised bacteria, living in the ice?
Nobody yet knows the answer.
This is just one of the many strange mysteries that draw people to
work in a place that is so hostile to human life.
While some scientists come to Erebus to explore its bizarre ice caves,
others visit the volcano to study the innermost workings of our planet.
Erebus is one of the most active volcanoes on Earth,
but even so, volcanologists work on the very rim of its crater.
They stand in the bitter cold, while 100 metres below them
is a lava lake where temperatures are over a thousand degrees centigrade.
This is a rare glimpse of the molten rock that lies beneath the earth's crust.
But research here is looking up as well as down,
measuring how the gases that bubble out of the volcano
influence the make-up of the air we breathe.
Antarctica is the best place to measure any changes in our atmosphere
because it has the least polluted air on Earth.
It's also the perfect place to launch more outward-looking missions.
This balloon, made of material no thicker than Clingfilm,
will eventually grow to be 300 metres tall.
It will carry a device for detecting cosmic rays,
tiny particles from the beginning of time that are only now reaching earth.
The balloon will travel to the very edge of outer space
to gather clues about the formation of the universe.
Even today, very few ever make the journey inland from the coast.
We still know remarkably little about the interior of the continent.
The people on this plane are trying to answer one of the fundamental questions.
How much ice is there in Antarctica?
They measure the depth of the ice sheet,
which is over 4,000 metres in places, using radar.
Their work will enable us to see
how the volume of Antarctica's ice changes in the future.
It also makes it possible to map a hidden landscape.
This plane is following the same route through the Trans-Antarctic Mountains
that Captain Scott took a hundred years ago.
His team hauled their sleds over a hundred miles up this glacier, the Beardmore.
Skirting seemingly endless crevasses, with no map to guide them
and no idea of what lay ahead, it was a journey of extraordinary suffering.
Their target lay beyond the mountains,
over 3,000 metres above sea level, on the Antarctic Plateau.
An unbroken sheet of ice, larger than Western Europe,
this is the coldest, the windiest, the most lifeless place on Earth.
Roald Amundsen's team narrowly defeated Scott's to become
the first people to reach the South Pole on the 14th of December 1911.
Nobody else successfully completed the journey for nearly 50 years after that.
But, since 1957, there has been a permanent base at the South Pole.
You can even land a plane on the ice runway.
The early explorers would be astounded by the facilities at the South Pole today.
Construction work isn't easy when the average summer temperature is minus 25 degrees Centigrade.
But, despite the difficulties, the most high-tech scientific research
station ever built was unveiled here in 2006.
The brand new Amundsen-Scott South Pole Station is designed to
cope with the World's most extreme conditions.
The building's sloping edge deflects the prevailing wind.
Beneath, there are stilts that can raise the whole building
a further eight metres to keep it above the accumulating snow.
Living inside is as close to being on a space-station as you can find on Earth.
This base is totally self-sufficient, the people are completely
cut off from the outside world for more than half the year over winter.
The total darkness makes this the perfect place to study the night sky.
The group of star gazers will be the most isolated community on our
planet, but they will have all their needs catered for.
There is even a greenhouse where fresh vegetables grow under
artificial light all through the darkest, coldest winter anywhere.
The sun sets in March at the South Pole, and won't rise again for six months.
For a few days at this time of year, high altitude clouds of ice crystals
continue to catch the sunlight, even when the sun itself is far below the horizon.
But soon all trace of the sun disappears,
and today's over-wintering scientists remember the first explorers.
These men, who endured the winter in flimsy wooden huts,
borrowed knowledge from the Arctic pioneers before them,
but they came here to study and explore, rather than to hunt or exploit.
They embodied the human spirit that has enabled us to survive at the poles.
Here, we are pushed to our limits, but in being pushed, humanity has
achieved the extraordinary and opened up the last frontier.
Next time, I'll be travelling to the ends of the earth,
to witness for myself how rising temperatures are dramatically changing the Frozen Planet.
I'll see how the animals are coping with their changing world
and find out how these changes might even affect the whole planet.
To tell the story of how we survive at the Poles, Frozen Planet
travelled to Siberia, the far north of Russia,
where most of the Arctic's people live.
The team got to know many extraordinary people.
But one group of men above all really opened their eyes to what it means
to live off the land in the most unforgiving environment on earth.
Men who take their life in their hands everyday, just to find their food.
Producer, Dan Rees, led the Frozen Planet team on their longest journey in the Arctic.
Their mission was to film walrus hunters in Russia's most remote region, Chukotka,
the closest point to their old enemy the United States,
4,000 miles and nine time zones east of Moscow.
It's still a sensitive region,
and the team soon learn that the border guards remain twitchy about foreigners with cameras.
GUARD: Nyet! Nyet!
To get permission to film, the crew relied on anthropologist Niobe Thompson,
one of the few westerners to have worked with the people here.
But even Niobe finds a lot of doors closed to him.
I have experienced a level of red tape I never could have anticipated.
We've got our Russian visas in our passports,
that's fine, but that's just the beginning.
Here is the special permission given by the security services to
be in the region of Chukotka,
a special permission to be in every one of the population centres we will visit on our trip,
permission to shoot with a telephoto lens,
permission to shoot from a helicopter,
permission to shoot in a natural reserve,
but we still don't have our migration cards.
I'm trying to get them, and if we don't get them by the end of the day
we're going to be deported back to Alaska, it'll take three months to get new ones.
Niobe's paper chase takes two days,
but finally the team is allowed to begin their journey to the hunters' camp.
With no roads, sometimes the only passable route is over
the fast melting surfaces of the lakes.
OK?
They need to be prepared for a quick exit.
The next day the crew finally reach the coast.
The hunting camp is now just 30 miles away across a bay, but the crossing could be risky.
The frozen sea is melting fast in the spring sunshine.
Confident it's safe? It's not going to break underneath us?
Is that the decision, 50/50?
50/50!
The locals employ several generations of arctic transport,
from the ancient to the merely antique.
With the sea ice cracking up beneath them, Dan has to trust the crew
and a ton of filming gear to the experience of the locals.
Even by their standards this was fast becoming a risky journey.
Where the first sleds crossed just minutes before is now impassable.
It's broken right up, we can't cross the leads in the ice here,
so we need to get on some boats, and the ice is just breaking up too fast for us at the moment.
Fortunately, the hunters from the camp turn up in the nick of time
to rescue the crew for the final leg of the journey.
Six days and 5,000 miles from home,
the crew finally arrive at the place that will be their home for the next month.
This is an active hunting camp and, that evening, the team
are introduced to the realities of fending for yourself in the Arctic.
Well, we've just seen a walrus hunt
out here in the waters of the Bering Sea.
All the meat will be eaten, they eat an awful lot of the internal organs as well,
they use the skin, they use the sinews,
they use the stomach for making drums, so it'll get used very heavily
and it is completely free range, you know, wild caught animal.
You can't grow any vegetables up here, but sea mammal meat contains
all the nutrients the hunters need and is very low in cholesterol.
Dan is keen to try some of Kolya's health food.
Well, this is yesterday's seal and a chunk of flesh there,
behind it is some intestine.
We should try a bit.
That's seal intestine.
It's quite fishy. Fishy, fishy rubber.
That's not too bad. I thought it was going to be more disgusting than it actually is.
The salt helps. Yeah.
Would he like to try what we eat? It's chicken, chicken korma.
No?
I don't blame you to be honest, yours is much better!
As well as providing food, the animals here traditionally provided transport.
Kolya and Pasha, the oldest hunters,
keep alive the skill of building walrus skin boats.
You don't need a welding torch to repair this boat,
just a juicy lump of seal fat to bung any holes.
By living amongst them, the crew had really begun to get to know the hunters,
but there was one big part of their lives which remained a mystery.
As spring turns to summer, the hunters head out to an island to gather seabird eggs.
The crew had heard stories of this, but had little idea of what it was going to involve.
That's where they climb, those are impressive heights.
Quite something.
For cameraman Ted Giffords, this was the first sight of the rock face he was about to work on.
These cliffs can be treacherous, as Kolya, the expert egg collector, knows only too well.
Ted will rely on steel stakes for anchors and an array of climbing gear and ropes.
Kolya preferred to stick with the simpler method that has served him well for many years.
The crew can't quite believe what they're seeing.
If he fell on that that would be absolutely horrendous.
It's...yeah, it's a bit sketchy, and the rope is only about that thick.
It's an interesting method.
The limestone cliff is loose and crumbling, because of hundreds of years of freezing and thawing.
Even for a highly trained professional climber like Ted, it's a dangerous descent.
Kolya has been climbing here for four decades, but this is the first time
he's had company, and sometimes he forgets that Ted is just below him.
Climbing supervisor Adam Scott holds his breath as he watches.
A fall to the rocks 100 metres below would almost certainly be fatal.
This is the most hardcore thing I've ever seen.
It was when the team returned to the boat to finish filming
that they got their most spectacular view of the lengths Kolya was going to, to get his dinner.
This shot sent the team home with a fresh perspective and a deep
respect for these people who still live off the land in the Arctic.
A way of life for which there is no safety net.
Subtitles by Red Bee Media Ltd
E-mail subtitling@bbc.co.uk