All language subtitles for BBC.A.Perfect.Planet.1of5.Volcano.1080p.HDTV.x265.AAC.MVGroup.org

There is only one planet
in the universe, as far as we know,

where there is life.

The Earth.

Our home.

The perfect planet.

Life here is only possible

because of a unique balance
of natural forces.

Energy from the sun
powers the living world.

GRUNTING

THUNDER CRASHES

Weather systems transport fresh
water around the globe.

And powerful ocean currents

circulate life's essential
nutrients.

This series will reveal how these
global forces have worked together

to create our planet's
fragile life-support system.

One of these forces is so important

that life would never have
even started without it.

Across the surface of our planet,

there are over 1,500 active
volcanoes.

This is the most active -
Kilauea in Hawaii.

Here, magma - liquid rock
from the planet's hot interior -

bursts out through fractures
in the Earth's crust,

and it's been flowing for months.

Nothing can stand in the lava's way.

Volcanoes are certainly destructive.

But without these powerful
underground forces,

there would be no breathable
atmosphere.

No oceans.

No land.

No life.

We can't control volcanoes,

but they're vital for all living
things on Planet Earth.

RUMBLING

This is Ol Doinyo Lengai
in Tanzania.

It's one of Africa's
most active volcanoes,

and has erupted over 15 times
in the last 100 years.

On its northern flank lies
Lake Natron,

400 square miles in extent,

and one of the world's most
corrosive bodies of water.

The water wells up from deep below,

carrying such a concentration of
chemicals that it can burn skin.

But one animal thrives here.

Volcano birds.

Nearly two million lesser flamingos
live in East Africa

and all of them come here to breed.

FLAMINGOS CALL

But they can only nest here
when the lake's level

drops so far that in the centre,
its bed is exposed.

And that rare moment is now.

How they know when the conditions
are right is a mystery,

but some have flown thousands
of miles to be here.

The flamingos head for the
middle of the lake,

where the intense evaporation
has created islands of salt.

It's here that the birds
build their nests,

over three miles from the
lake's edge

and safe from land predators,
which are unable to cross

the surrounding moat of
caustic soda.

FLAMINGO CALLS

The single egg is laid on a mount
of hardened salt

built by the adults,

its height an insurance against
a sudden rise in water level...

...which often happens on
Lake Natron.

As the centre dries and enlarges,

more and more flamingos arrive
to nest on it.

In good years, such as now,

as many as half a million pairs
breed here.

After 28 days of incubation,

a chick emerges into Natron's
harsh glare.

Here, temperatures can rise
to 55 degrees Celsius.

Mother's wing, however,
can serve as a sun shield.

CHICK CHIRPS

The chick is fed a rich liquid

made of the lake's
barely digested algae

and traces of its parent's blood.

After a few days, the chick is
strong enough to stretch its legs.

CHIRPS

CHIRPING

It then joins a growing creche,
made up of chicks of different ages.

Soon, the need for fresh water
will force the infant birds

to trek to springs on the
lake's edge.

A journey they have to make on foot,

as their flight feathers
have yet to develop.

Every day, the adults fly
to these springs to feed.

Here, on the lake's margins,
they collect algae that flourish

in the volcanic water -

vital food for the flamingos.

It's the algae that turn
the flamingos' feathers pink.

It even colours their eyes.

The adults spend most of their day
at the springs,

and now their chicks
are going to join them there.

CHIRPS

No-one wants to get left behind.

It's a three-mile march
over razor-sharp flakes of soda

and sticky, caustic mud.

A life-threatening trial,
especially for the youngest chicks.

The groups merge into one
giant creche.

CHIRPS

For some, the challenges
are just too great.

Exhaustion overcomes the weakest.

And now, there is yet
another threat.

Marabou storks.

They have long legs like a flamingo,

but a beak like a Roman sword.

And they are patient,

waiting for an easy target.

Their very presence creates panic
among the chicks.

The smallest avoid
being trampled underfoot

by travelling on the outside
of the group.

But that exposes them to attack.

Their only defence is to run.

But you have little chance

when you're barely ankle-high
to your pursuer.

FLAMINGOS SHRIEK

Stragglers will almost
certainly be taken.

But there comes a point
when every stork has had its fill.

This little chick is very lucky.

At last, the youngsters reach
the freshwater springs

at the lake's margin
to rejoin their parents.

Almost unbelievably,
each chick has a unique call

that its parent can recognise.

CHICK CHIRPS

CHIRPING

Ultimately, so do all living things.

Over 80% of the Earth's surface

is the result of magma bursting up
from the molten interior.

BOOM

The process started
four billion years ago

and it still continues today.

When lava cools, it solidifies
into rock,

and eventually weathers into land
that can support life.

All the Galapagos Islands
in the Pacific are volcanic,

and Fernandina is the
youngest of them.

And still growing.

At its centre, a volcanic crater
four miles wide...

...and over 800 metres deep.

It seems dormant, but it was
erupting only two weeks ago.

Even so, there are some who depend
on the heat from this volcano.

A female land iguana, heavy with
eggs, approaches the crater's rim.

It took her ten days
to climb up here,

but the toughest part of her
journey is still ahead.

She's going to descend
into the crater itself.

Frequent tremors
make the crater walls unstable.

More people have travelled in space

than have visited the bottom
of Fernandina's crater.

But instinct drives her on.

The warm volcanic ash on
the crater floor

has the perfect temperature
for incubating her eggs.

But there are no clear paths down.

Any made last year have been
destroyed by rock falls.

The slope is steep and unstable.

Tumbling rocks
quickly become an avalanche.

With the boulders falling down
away from her,

she's not in immediate danger.

But behind her, higher up,

two other females
have also started the descent.

ROCKS RATTLE

And now she is in the firing line.

THUD

She's safe.

FLIES BUZZ

Others before her
haven't been so lucky.

But she's undeterred.

At last, after an eight-hour
descent,

she reaches the crater floor.

Now she must find a suitable
place to dig her nest.

The best sites are already taken.

And nesting females are very
aggressive.

A nodding head means keep away.

Push off!

Ignored warnings are met with force.

But she's come a long way,
and she's not going to give up now.

She, too, starts to dig a hole
in which to lay her eggs.

That done, she will head back,

leaving the volcano to provide
the warmth her eggs need

if they are to hatch.

Sometimes, of course,
the volcano erupts

and destroys not only eggs
but many nesting adults.

But for the iguanas,

the benefits of nesting in
the crater are so great

that it's worth all the risks.

Volcanic islands make up just 5%
of the planet's land,

but they're home
to nearly 20% of its species.

Animals often evolve very
swiftly on islands,

cut off from their mainland
relatives

and faced with the challenges
of isolation.

This is Wolf, an extinct volcano

and one of the most remote islands
of the Galapagos,

800 miles from
the nearest large landmass

and over a million years old.

A finch.

A female.

Its ancestors doubtless were blown
here by storms many centuries ago.

Like most finches, they feed on
seeds, nectar and insects.

But there's little food
of any kind on Wolf.

CHIRPS

And since they aren't strong enough
fliers to leave the island,

they've had to find food
from a very unusual source.

They depend on another
of the island's inhabitants.

BIRD CALLS

Nazca boobies.

Every day, these sea birds commute

between the island and their fishing
grounds out in the open ocean.

Each time a pair meet,
they renew their bond.

And then catch up with the
neighbours.

CAWING AND CHIRPING

Now is the time...

...to hop into action.

CHIRPING

Blood.

They are vampire finches.

These little birds have become
one of the world's newest species.

She cuts the quill
of a large flight feather,

and the blood flows.

The sight of it attracts the
attention of others.

CAWING AND CHIRPING

Blood is very nutritious -
worth fighting for.

So with this never-ending supply
of food,

the vampire finches
can flourish on an island

where otherwise they could
not survive.

Why the boobies don't object,
nobody knows.

Perhaps the finches' behaviour
started

when they helped the boobies to
remove parasites from their plumage.

Maybe the boobies
think that the little vampires

are still providing a service.

Who can tell?

Volcanic islands don't last forever.

Changes deep in the Earth's crust
bring their eruptions to an end

and the forces of erosion
then begin to wear them down.

BIRDS TWEETING

But the coral around them
continues to grow,

sea levels change,
and eventually all that is left

is a ring-shaped island of coral
rock surrounding a lagoon.

An atoll.

There are hundreds of atolls
in tropical seas,

all remnants of vanished volcanoes.

This is one of the largest
and most pristine -

Aldabra, in the Indian Ocean.

20 million years ago,
it was an island

with a volcanic crater in
its centre.

Now, it's an atoll.

Mangroves took root
and sea birds came to nest.

One land animal in particular...
GRUNTS

..reached here before man.

GRUNTS

A giant tortoise.

These creatures can float

and live without food or fresh water
for long periods of time.

This isolated atoll is the
perfect refuge.

Their only enemy is the sun.

Without shade, a tortoise risks
being boiled in his shell.

So, after feeding
in the cool of the morning,

and before the sun
becomes too crushingly hot,

they have to find cover.

All of them.

There is very little vegetation,
but caves in the coral rock

can provide the shade
they so badly need.

He's nearly there.

All that is left is a white-knuckle
ride to the bottom.

GRUNTS

And he's in.

Thousands of others
are still out in the sun.

This tree could shade a couple
of hundred, if they pack tight.

It's bumper-to-bumper parking.

Within an hour or so,
all must find shade of some sort

if they're to survive.

Safe.

GRUNTS

But the future for Aldabra's
tortoises is far from certain.

The climate is changing,
sea levels are rising,

and Aldabra's tortoises may soon
have to find a new refuge,

or drown.

In some places, volcanoes erupt
not in the ocean

but in the very middle
of a continent.

North America.

And in its very heart,
a volcanic hot spot - Yellowstone.

The last major eruption here

came to an end about
650,000 years ago,

but this volcano is only sleeping.

Not far below ground,
there is still magma.

And that heats the ground water
to boiling point.

BOOM

Geysers.

Some spout boiling water and steam
to heights of 90 metres or so.

Elsewhere, the scalding waters
liquefy the ground sediments,

creating pots of boiling mud.

And this underground heating
has proved a lifeline for some.

River otters.

SQUEAKS

They need a constant supply of food
if they're to keep warm

in these freezing temperatures.

And this close-knit family
know exactly where to find it.

The springs are so hot that the
rivers never freeze,

even in the coldest winters.

SQUEAKS

So the otter family can fish
the year round.

GROWLING

Trouble.

This coyote knows that
in the middle of winter,

a thermal river means otters,

and otters mean fish.

The question is
how to steal their catch.

Perhaps the thing to do is to
pretend you're not interested...

..and hope that they wander close
enough for a snatch-and-run raid.

It seems the cool-under-fire otters

can outwit the not-so-wily coyote.

Many animals benefit
from the volcanic heat

coming up from below.

OTTERS CALL

And we do as well, but not nearly
as much as we could.

The volcanic heat could provide us

with much of the energy
that we need,

and then we could stop
burning gas and coal

that is now changing the
climate worldwide.

Deep in the Earth's crust,

below both the oceans
and the continents,

there are lines of weakness
along which rises liquid rock.

The Kamchatka Peninsula
in the north-west Pacific

lies along one of them.

There are only a thousand known
geysers in the world,

and many of them are here
in this isolated valley.

BOOM

Steam from superheated water
fills the air.

But the danger from the scalding
pools does little to deter

Kamchatka's most famous residents.

GRUNTS

In May, when the rest of Kamchatka
is still covered by snow,

this valley is free of it,

and bears, having just woken up from
their winter sleep, know that.

The grass is fertilised
by mineral-rich water

spraying from the geysers.

Much-needed forage for
a large male bear

that hasn't eaten for
several months.

And he's not the only one.

The bears haven't seen one another
for seven months,

since the start of winter.

And it seems that right now, they
would prefer to keep it that way.

Nothing should come between a bear
and his first meal of the year.

And in one place,
Kamchatka's underground forces

provide its bears
with even more nutritious meals.

Kurile Lake lies within the crater
of an immense volcano

that long ago produced one of the
greatest eruptions

in the planet's history.

The lake is still circled
by active vents...

..and mineral-rich ash
from their regular eruptions

has made these waters
particularly fertile.

Millions of salmon come
here from the Pacific Ocean

in order to spawn in
these fertile waters,

which will provide their newly
hatched young with abundant food.

So, grass soon ceases to be top
of the menu for Kamchatka's bears.

By the time spring
has turned to summer,

Kurile Lake contains the
most dense assembly of bears

to be found anywhere on Earth.

All hungry for salmon.

SEA BIRDS CALL

But this early in the season,
the fish are still strong and swift.

Nothing seems to work.

But one old bear knows that,
right now,

there is an easier meal to be had.

He remembers that if he
paddles out into the lake,

away from the shoals
of newly arrived salmon,

there's food that
doesn't need chasing.

Some of the first fish
to arrive have died,

and their bodies can
be easily collected...

BEAR GRUNTS

..from the bottom of the lake.

Diving for them at leisure
doesn't use many calories.

And he can take his time.

A couple of weeks later,

the salmon are beginning
to spawn and are less wary.

Now it's worth running.

The fish are so abundant...

..that there is plenty for all...

..even those with no
previous experience.

There are now so many fish,

it's difficult to know
which one to chase.

In a single day, a bear can
consume 100,000 calories,

50 times more than the
average human being does.

And one part is
particularly delicious...

..caviar.

80 calories in every mouthful.

BEARS GRUNT

By supporting huge
concentrations of salmon,

mineral ash from
Kurile Lake's volcanoes

has made life surprisingly
easy for these bears.

EXPLOSIVE BOOM

Our planet depends on minerals
brought up by volcanoes

from the Earth's molten core.

A single ash cloud can carry
billions of tonnes of minerals.

And as a consequence,
the lands surrounding volcanoes

are among the world's most fertile.

Those in East Africa's Rift Valley

support the most dynamic
ecosystem on Earth.

The Serengeti.

This is the most productive of
all natural grasslands anywhere.

Every year, over a
million wildebeest

assemble in this particular
corner of the Serengeti

to feed on grass especially
rich in calcium and phosphorus,

essential minerals
for the pregnant females.

In just three weeks,
half a million calves are born

on these ash-rich plains.

That's 24,000 a day...

..a thousand an hour.

Calves stand up within a
few minutes of being born.

Though some need a little
more time to find their feet.

But a mother won't
let her calf suckle

until it's mastered
a few physical skills...

..walking...

..trotting...

..and running.

WILDEBEEST SNORT

Wildebeest calves must run
if they're to stay alive.

HYENA CACKLES

For these plains also support

the greatest assembly
of hunters on the planet.

Each species has its own
special hunting technique.

But all have the same aim...

..to make the most of this
brief super-abundance of life.

PANTING

HEARTBEAT THUMPING

Only one in ten wildebeest
calves will survive to adulthood.

But that is enough to maintain the
million-strong herd of wildebeest...

HYENA WAILS

...AND the planet's highest
density of predators.

Volcanoes fertilise the planet,

but they're the source of
something else so important

that life could not
have started without it.

The first carbon dioxide
in the Earth's atmosphere

was brought by volcanoes
from deep in the Earth's crust.

BIRDS CALL

And this gas is the
foundation of life.

Every plant needs it to grow,

and absorbs it from the air.

Volcanoes continue to
release carbon dioxide today,

and for the last 10,000 years,

its presence in the atmosphere
has suited life perfectly.

Its greenhouse properties have kept

our planet's climate
stable and warm.

EXPLOSIVE BOOM

But too much carbon dioxide would
make the planet's temperature

rise to levels that
would upset the Earth's

long-established
ecological balances.

EXPLOSIVE BOOM

Today, humanity itself

has become a new
kind of supervolcano.

EXPLOSIVE BOOM

Now, every year, we ourselves
release 100 times more carbon

than all the Earth's
volcanoes combined.

And that has brought climate chaos.

We can't control volcanoes,

but we can limit the amount of
carbon dioxide that we produce.

And if we do that,
there will still be time

to restore the ecological balance

that once made this Earth
our perfect planet.

DAVID ATTENBOROUGH:
Lake Natron, in Tanzania

is one of the world's
most toxic bodies of water.

Yet once every few years,
when the centre dries out,

it's brought to life by
thousands of breeding flamingos.

But to reach the colony,

there's only one way to
cross this soft soda sludge.

It's finally here.

Our secret weapon...

..is a hovercraft.

And it's beautiful.

Having shipped it from the UK,

Darren's keen to test
that all systems are go.

ENGINE REVS

Getting it off the
trailer is one thing,

but at least the hovercraft's fans,
that give it lift,

are working well enough.

COUGHING AND LAUGHTER

Well, guys, what do you think?

We know she works, but...
COUGHING

..maybe some of these
guys' lungs don't now.

125 miles away,
on the edge of Lake Natron,

cameraman Matt Aeberhard is
trying to camouflage his hides.

Those are our blinds.

So, you can't camouflage
those on the flats,

and the best thing that
we can do is actually

turn them into a little
cluster of flamingos.

It's pretty cool, huh?

Hide complete, all that's needed
is transport out to the colony.

And after a ten-hour
cross-country journey,

Darren arrives with
his secret weapon...

..and it's an instant hit.

It's the new local
tourist attraction.

You like it?

The first job is to get the
hovercraft into service

and plot a route out to
the nesting flamingos.

The volcanic spring water
is soon replaced

by a crust of razor-sharp
salt crystals.

And for a machine that relies
on a delicate blow-up bottom,

that's a problem.

So, what we have here are
the plates of dried out soda

which form on the mud
substrate underneath,

and it just batters the hovercraft.

We just cannot travel
across this stuff.

It's impossible.

If I was to skim my hand across
that, I would cut it to shreds.

But crossing the soda crust is the
only way out of to the colonies,

and so Matt and Darren
have to hope for the best.

DRILL WHIRS

Unfortunately for Matt,

the best position for his
flamingo-covered hide

has a rather soggy floor.

When the mud dries, it leaves
massive amounts of salt.

Very scratchy, nasty
and aggressive salt.

But sitting shin-deep
in toxic sludge

is a price worth
paying for the view.

And Matt is soon rewarded
with the birth of a chick

right in front of his hide.

CHICK CHIRPS

The daily commute, however,

is taking its toll
on the hovercraft...

ENGINE STALLS

Oh, come on!

..and its blow-up bottom is
literally being ripped apart.

We've trashed 52 of these
that now need to be repaired.

It's like travelling over sandpaper.

So, what do you do when
your hovercraft needs

replacement skirts and you're
in the middle of nowhere?

Enter the local Maasai tribe,

well known for their
needlework skills.

There are only a few places
in the world that specialise

in hovercraft maintenance,

and Lake Natron is now
officially one of those hot spots.

So if you're in the need
of any hovercraft services,

you know where to go.

Two days later, and after
a lot of serious sewing,

the hovercraft is
ready to ride again.

ENGINE TURNS OVER

You look like the new
Tanzanian bobsleigh team!

And getting back on the lake
couldn't have come at a better time,

as the chicks are now on the move.

Sadly, the new hide
position is no drier.

We have an enormous creche of
hundreds of thousands of birds

just pouring into the lagoon
from the salt mud,

just constantly
chatting to each other.

But the massive creche attracts
some unwelcome visitors...

...predators - marabou storks.

These marabous, they know
exactly what they are doing.

Soon, thousands of panicked
chicks are on the move,

desperately trying
to avoid the predators.

And it's a scene that will
live long in Matt's memory.

I mean, it was literally like...

..war had been declared.

I mean, that's one of the...the...

...most amazing and frightening
and freaky wildlife scenes

I've ever, EVER seen.

And believe me, I've seen a few.

And few places are more
challenging than Lake Natron,

but to quote Matt,
if you can deal with

the acrid and sulphurous
stink of the soda,

the stinging eyes and the
chemical attack on your legs,

then you could be rewarded with one
of the greatest spectacles on Earth.

Next time...

..the sun.

Life on our planet is
fuelled by its energy.

Everything must be perfectly tuned

to the daily and yearly
rhythms of this vital force.

The Open University has
produced a free poster

exploring our perfect planet.

To order, please
call 0300 303 0901.

Or go to bbc.co.uk/perfectplanet

and follow the links
to the Open University.