Seven Worlds, One Planet

200 million years ago,

our planet looked very different from what it does today.

It was entirely covered by sea,

which surrounded one single supercontinent we call Pangaea.

And then Pangaea began to break up.

Life was cast adrift on fragments of land.

And these fragments eventually became our seven continents.

We will see how life developed on each continent,

giving rise to the extraordinary and wonderful diversity that we see today.

We'll venture to the frozen wilderness of Antarctica...

...where life thrives against the odds...

...and to the riches of South America,

full of the unexpected...

...from the wilds of Africa...

...to the vast expanses of North America

and the searing heat of Australia.

We'll explore the remote reaches of Asia...

...home to rarely seen creatures...

...and Europe, a world transformed by humanity.

And we'll discover how this may be the most critical moment for life on Earth

since the continents formed.

We are changing the world so rapidly

that wildlife is now facing some of its greatest challenges yet.

Never has it been a more important time

to reveal the precious diversity of life

on our seven continents.

This is Seven Worlds, One Planet.

Of all the continents...

...one was first sighted by humans just 200 years ago.

And only now are we beginning to understand what it takes to survive here.

It's the most hostile of them all.

98% of mainland Antarctica,

an area one and a half times the size of the United States,

is covered in ice...

...on which virtually nothing can live.

50 life is dependent on the ocean that surrounds it.

But even the ocean freezes.

Only one mammal can live this far south...

...the Weddell seal.

SEAL GRUNTS

She has to keep her breathing hole open

by grinding back the ice with her teeth.

Out here on the sea ice,

all these seals are far from the predators of the open ocean...

...so this is the safest place for her to give birth.

Leaving the warmth of the womb and landing on ice

is the sharpest drop in temperature any animal ever faces.

PUP MEWLS

But her pup can't swim for the first ten days of its life.

It's trapped here, out on the ice.

WIND GUSTS

PUP MEWLS

She shields her pup from the wind.

Although it's spring, temperatures can drop

to minus 40 degrees Celsius

and blizzards can rage for days.

Three days on, and the storm is still raging.

She now faces the hardest of decisions.

Does she stay with her pup?

MEWLS

Or shelter in the water?

Now her pup's best chance of survival is for the storm to pass quickly.

WIND HOWLS

Some pups didn't make it.

YOWLS

MEWLS

An answer.

YOWLS

MEWLS

If this pup nowjoins its mother in the water,

it will be safe from any future storm.

It's minus 2 degrees Celsius,

but being in water is warmer than lying on the ice in the howling wind.

Its chances of surviving here are now extremely good.

Only a few hardy animals can live all year round as far south as this.

Further from the Pole, on the fringes of the continent,

lie islands that are free of sea ice.

CAWING

Here there are other challenges.

Saint Andrews Bay on South Georgia

is packed with half a million king penguins.

In spring, the chicks are left for days

whilst their parents are away collecting food for them.

There is a simple arrangement.

The chicks must stay exactly where their parents left them

to be sure of being found again.

CHEEPS

CHEEPS

But this chick has decided to look around.

There is a lot to be investigated.

CHEEPING

But it must not stray too far from its meeting place.

This parent has returned with food in its crop.

But its chick isn't where it left it.

It's hard to stay put when there's so much to play with.

GRUNTING

Elephant seals are here too.

Very mysterious.

SEAL GRUNTS

SEAL GRUNTS

GRUNTING

Finding it in the crowd of youngsters is not going to be easy.

They must recognise each other by their calls.

CAWING AND CHEEPING

CHEEPS

But to hear these in such a noisy colony

they must be within 15 metres of each other.

CAWS

CHEEPS

CAWS

CHEEPS

Reunited.

Saint Andrews beach is one of the most crowded on the planet,

and so holding a territory here is a constant battle.

This bull elephant seal holds the mating rights to 60 females.

GRUNTS QUIETLY

For two months, he's guarded this stretch of beach.

Unable to feed, he's losing ten kilos a day...

...and he's exhausted.

But other bulls are lying around, waiting their chance.

GRUNTS

GRUNTS

PENGUINS CAW

GRUNTS

GRUNTING

Blubber 15cm thick

is protection against the cold,

but not from the impact of a four-tonne opponent.

He holds his ground and forces the intruder back out to sea.

Life in the Antarctic is harsh indeed,

but all these creatures come here

because the Southern Ocean is one of the richest on Earth.

When, 30 million years ago,

the continent broke away from South America and drifted south,

currents began to swirl right around it.

They are now the strongest of any currents on the planet.

They sweep up nutrients from the depths

and so create one of the richest feeding grounds in all the world's oceans.

And some of the creatures that come here to feast

do so in a most sophisticated way.

Humpback whales.

It's summer, and they've come here for a banquet.

The cold waters contain great shoals of krill.

It's estimated that there are 400 trillion of them

and that their combined weight is greater

than that of any other animal species on the planet.

To collect them, the humpbacks blow curtains of bubbles

which the krill won't cross.

The whales then rise,

spiralling inwards to concentrate the swarm.

Summer in Antarctica is a time of plenty,

when most humpbacks are able to put on the reserves they need for the whole year.

But the wildlife in these waters faces an uncertain future.

The Southern Ocean is warming.

90% of the world's ice lies in Antarctica,

and in some parts the rate at which it's melting is doubling every decade.

Sea levels are rising.

But there is a more immediate threat.

The warming of the coldest region on Earth

is having a profound effect on global weather patterns.

And this change in the climate is already being felt right here.

SQUAWKING

This grey-headed albatross chick is four weeks old.

So far, it has been sheltered from the gales by its parents,

who take turns to collect food for it out at sea.

It is the only chick that they will have in two years.

CHEEPS

A delicate touching of beaks strengthens their bond.

But these tender moments cannot last for ever.

As a chick grows, so does its appetite,

so one parent has to leave to find food before the other returns.

CHEEPS

Parting is a big step,

and they take time over it.

CHEEPS

For the first time in its life,

this chick is alone.

The Antarctic is the windiest continent,

and in recent years, climate change has brought storms

that are more frequent and even more powerful.

WIND GUSTS

Winds now regularly reach 70mph.

But the albatross chicks must try to stay on their nests.

CHEEPS

Surviving the storm is one thing...

...but now, off the nest in these freezing temperatures,

this chick has just hours to live.

The brutal conditions have taken their toll.

Some chicks have already succumbed to exposure.