All language subtitles for 3) A Perfect Planet-Weather

A Perfect Planet.

We live in a world with
a violent atmosphere.

Rain clouds form,

and powerful winds carry their
fresh water around the globe.

Without this, our perfect planet
simply couldn't function...

for all life on land
depends on the weather.

We all know that the weather
can change on a daily,

even hourly, basis.

But annual weather patterns
have been stable for millennia...

and it's this reliability
on which life depends.

Every year in October, the weather
brings a dramatic transformation

to this tiny patch
of forest in Zambia.

Storm clouds begin to build.

And right on cue, straw-coloured
fruit bats start to appear.

They've travelled hundreds, if not
thousands, of miles to be here.

And they always arrive
at exactly the same time.

They know that these rains
will transform this forest,

allowing countless
fruit trees to ripen.

And the bats gorge on
the new-found abundance.

For just 12 weeks every year,

this forest becomes home
to ten million fruit bats.

One of the greatest gatherings
of mammals on Earth,

all crowding into an area no bigger
than a dozen football pitches.

From this hub, the bats fan out,

consuming more than
300,000 tonnes of fruit,

spreading the seeds and
regenerating the forests.

Africa's largest wildlife migration
entirely dependent on the rain

that comes to this
small corner of Zambia

at the same time each year.

Every second,
over 13 million tonnes of water

evaporate from our oceans,
forming clouds.

The spin of the Earth
and the prevailing winds

determine where these clouds blow.

As a consequence,
some places get less rain...

and others much more.

The Amazon rainforest...

one of the wettest
places on Earth.

It gets three metres
of rain a year...

so life has learned to deal
with the near-daily downpours.

Every year, for thousands of years,

the persistent rains have flooded
vast tracts of the Amazon...

turning the jungle
into a seasonal wetland.

Anything living here
must either climb or swim.

But there's one extraordinary
animal that has turned this deluge

from a disaster into an opportunity.

This fire ant has reached
the edge of her known world.

Her way forward has now become
blocked by the rising waters.

She's one of many,
and in a few minutes

their underground home
will be submerged.

Forced to evacuate,
workers and soldiers try
to save the larval young.

As their nest floods,
the colony seems to be doomed.

But from chaos comes order.

The fire ants band together, each
locking legs with its neighbours.

They're building a living raft.

Each ant is covered in fine hairs
that trap air against its body.

As the raft forms, this air creates
a cushion for them all to float on.

This is the power of the colony.

By working together,
they've become unsinkable.

And no-one gets left behind.

Pulled from the shallows, the colony
is now at the mercy of the flood.

Holding tight to the larvae

and keeping their queen hidden
at the centre of the raft,

the colony drifts
into deeper water...

where they're vulnerable to fish

that now swim through
the flooded forest.

Those that lose their grip must
get back to the safety of the raft.

With jaws that join to
become a surgical needle,

this pond skater
could suck an ant dry.

But together the colony is strong,

and it's time to repel boarders.

The ants can travel
like this for weeks.

They've even come to depend
on the flood to carry them

to new feeding grounds.

At last, the ants can
make their raft secure.

Surging forward, they
claim their new home...

evicting current tenants
without hesitation.

One of the first to safety
is their larval queen,

carried from the heart of the raft.

This palm will be their home
for the next three months,

until the floodwaters recede
and they can head back underground.

The average temperature
of our planet hasn't varied

by more than a single degree
Celsius in 10,000 years.

This has made our climate stable,

allowing animals to
fine-tune their behaviour

around predictable weather patterns.

October in the Amazon.

The heaviest rains
have come to an end,

and the falling river level
exposes a new landscape.

Three weeks ago, these mile-wide
sand bars didn't exist.

In another three months,
they'll be back under water.

But now they provide a crucial
opportunity for giant river turtles.

They've been coming here
at precisely this time
of year for generations.

50,000 of them - a quarter
of the world's population.

They're all here for one reason.

But their window of
opportunity is short,

so timing is everything.

Scaling the three-metre-high
banks will take this female

higher and drier than
she's been for months.

She's come here to lay her eggs.

But others have beaten her to it.

The early arrivals
have already claimed

nearly every inch of the beach...

and there are still
many more turtles to come.

Wherever she turns,
the space is taken.

But being fashionably late
does have an advantage.

Had she arrived earlier,
her eggs might have been

dug up by those searching
for somewhere to lay.

She's found her spot.

Settling down, she lays
nearly 100 eggs.

Burying them keeps them
safe from predators,

and the warm sand
incubates the clutch.

They must hatch before the river
rises again and floods the sandbar.

Any turtles that lay after her
may have left it too late.

Hopefully, she has
got her timing right.

Two months on, and the hatchlings
emerge into the world.

They were laid at the perfect time.

Hundreds scramble for the river

just as the water starts to rise.

Those still to hatch
aren't so lucky.

This year, the heavy rains
have returned early.

The nesting beach is
beginning to flood.

Most hatchlings can escape in time.

Those still below ground...

will drown in their nests.

For thousands of years, giant river
turtles have timed their breeding

around the Amazon's
reliable cycles of rain.

But today, our weather is changing.

Disastrous early floods like this
used to happen once every 20 years.

Now the turtles have to
deal with them every four.

Winds may carry huge amounts
of rain to the Amazon,

but they don't provide this service
to every corner of the planet.

A third of the land receives
less than 25cm of rain a year.

Deserts are scarred by desiccating
winds and baked by the sun.

But even weather as challenging as
this can be perfect for the locals.

As darkness falls in the
coastal deserts of South Africa,

the dunes come alive...

with the call of a
surprising desert dweller.

A rain frog.

Not what you'd expect in a place
that gets just 7cm of rain a year.

To survive here, she has
to avoid the heat of the day

buried in the sand.

But each night, she heads out...

..on her hunt for moisture.

Short, stumpy legs and a plump body
are ideal for digging...

but not so good
for getting around.

She can't hop, so she
waddles across the dunes.

The world's slowest steeplechaser.

Obstacles are tackled
with dogged perseverance.

She can travel a whopping
38 metres a night.

No mean feat when you're the same
size and shape as a marshmallow.

Termites.

They are 75% water -

a meal and a drink in one.

But she's not the
most agile predator.

Maybe if they just
came a little closer...?

Oh, dear.

Perhaps if they stop moving...?

At last.

But now she has another challenge.

To swallow her food, she
must squash in her eyeballs

to push it down her throat.

Termites may be juicy,

but they don't provide her with
quite enough water to survive.

It rarely rains here,

but coastal deserts do get another
reliable source of moisture.

At night - cool, moist air
is blown in from the ocean,

forming fog banks that
shroud the desert in mist.

It condenses on vegetation,
wetting the sand beneath.

So it's here that she waits,
absorbing moisture through her skin.

Rain frogs are so dependent on this
water that they can only survive

in places with at least
100 days of fog a year.

And on the foggiest nights,

when other frogs have
emerged onto the dunes,

she takes her opportunity
to find love.

Male rain frogs are
smaller than the females,

and his stubby legs
make it hard to hold on...

..so he glues himself onto her back.

Still locked in their embrace,

the pair head back beneath the sand,
where they'll lay their eggs,

safe from the heat
of the desert sun.

But there's one desert
that gets so cold

that liquid water
simply can't exist.

Winter in Mongolia's Gobi Desert.

40 degrees below freezing.

One of the driest and most extreme
environments in the world.

Most animals can't survive
weather like this...

but there's one unique mammal

that manages to eke
out a living here.

The Gobi is home to the last 1,000
wild Bactrian camels on Earth...

surviving at the very
edge of what's possible.

Even camels need moisture,

but any water here
is now frozen solid.

It's down to the bull
to find a solution.

Setting off with his herd,

his search could cover
thousands of square miles.

Driving them forward, he can
keep going for days on end.

Herds come together from
across their vast range...

all looking for the same thing.

These long-distance specialists can
smell moisture from 30 miles away...

and they've picked up a scent.

Even in the Gobi, one of
the driest places on Earth,

wind can provide a rare
source of moisture.

Snow is blown to this
desert from Siberia.

Where it settles is
impossible to predict,

and it may not last long.

But for now, at least, this bull has
found what he's been searching for.

In the cold, dry air,

snow doesn't melt...

so it must be eaten.

The Gobi's windblown
snow is a lifeline

that will sustain his herd
throughout the winter.

Even in this most hostile of places,

weather still provides
just enough for survival.

The largest, most unpredictable
weather on the planet

starts far out at sea.

Hurricanes, typhoons
and tropical cyclones

are violent, short-lived megastorms.

But there's a far more
reliable weather system

that originates over the ocean...

one that is eagerly
anticipated by all in its path.

Monsoons are seasonal winds that
blow at the same time each year...

and they carry colossal amounts
of water from the ocean to the land.

Christmas Island.

A remote speck of rock
in the Indian Ocean.

For the last four months, its forest
interior has remained dry and dusty.

Life here is waiting for change.

In November, the first storms
of the monsoon reach the island.

They're a welcome relief for those
that have suffered through the dry.

And they are vital for the island's
most numerous residents.

The red crabs of Christmas Island.

They've spent the dry season
sheltering in damp burrows

beneath the leaf litter.

Crabs breathe through gills
that must be kept moist.

So it's only with the return
of the annual monsoon

that these land crabs
can finally emerge.

With the humidity now high enough,

they can begin an
epic trek to the coast.

Every red crab comes together
from across the island,

and they do so in their millions.

50 million, to be precise.

They've come to release their eggs
that can only develop in the ocean.

There's just one small problem.

They may be crabs...

but they can't swim.

They're scared of the sea.

But they don't have a choice.

They must release their eggs
on the highest tide.

Each carries around 100,000 eggs,

so over just two or three nights,

trillions are released
into the ocean.

Though some are more
successful than others.

Once their work is done,
the crabs will return to the forest.

Then, four weeks later,

on the next highest tide...

having hatched out to sea,

a new generation of red crabs
returns to the same beach.

In good years like this one,

countless millions arrive back on
the shores of Christmas Island,

turning the beaches red.

Like their parents, they also need
moisture in the air to breathe.

So before the rains move on,

the young crabs must undertake their
own epic journey into the forest,

where they'll wait out
the next few months of dry.

The Christmas Island crab -

entirely reliant on the
return of the monsoon.

The annual rhythms of the weather
shape life across our planet.

In some parts of the world,

seasonal cycles of wet and dry
can bring dramatic change.

And there are few places
where this is more apparent

than southern Africa.

The Zambezi River.

It flows across six countries and
drains half a million square miles.

At the peak of the wet season,

5,000 tonnes of water cascade
over Victoria Falls every second.

And yet, each year
when the rains stop,

these falls run dry.

It's almost as if someone
turns off the tap.

May...

..December.

Wet season...

..dry season.

It's happened like this
for thousands of years.

But there are signs that
the weather here is changing.

In recent years, the volume of
water flowing over Victoria Falls

has dropped by half.

A concern for animals
that have come to rely on

the natural rhythms of wet and dry.

Zambia's Luangwa River is a
major tributary of the Zambezi.

Every year, as the
dry season takes hold,

it dwindles into pools.

Accommodation starts to
get tight for the locals.

With no other water around, the
river becomes a magnet for visitors.

Millions of red-billed quelea
flock to the water's edge.

These seed eaters need
to drink every day...

and Nile crocodiles know it.

They may not have
eaten for six months.

For them, the dry season is
the start of the good times.

And they are not the only ones
to depend on this time of year.

Carmine bee-eaters have
flown hundreds of miles

from the rainforests of the Congo...

arriving at the
peak of the dry season,

when steep sandbanks are
exposed by the falling water.

They're a perfect place to nest,

out of reach of
predators from above.

Bee-eater burrows can extend for
two metres into the soft river sand.

Already home to 6,000 nests,

real estate at Bee-eater Towers
is in high demand.

But it pays not to build
too close to the neighbours.

As more birds arrive, competition
for the best nesting sites heats up.

It's thirsty work.

In the sudden commotion,
they're vulnerable from below...

and above.

African fish eagles.

They are permanent residents here.

But at this time of the year,
they don't just eat fish.

The safest place to be
is inside a burrow.

But an eagle fly-by sends shock
waves of panic through the colony.

The eagles' strategy is to pin
their prey against the river bank.

With the colony in disarray,

the predators have the advantage.

These fish eagles also choose
to breed in the dry season,

because they need the bee-eaters
as food for their chicks.

But this year's dry season
shows no sign of letting up.

Parts of the river are now bone-dry,

forcing huge male hippos
from their home.

With nowhere left to turn,

they must converge on the few
remaining patches of water...

..but these are already occupied.

The resident bull here can't
tolerate another big male

in his shrinking pool.

The newcomer is banished.

Still the sun bakes the land...

with devastating consequences.

Hundreds of nests are wiped out.

Southern Africa has
experienced dry seasons

for thousands of years.

But this is something different.

Record high temperatures and the
lowest rainfall in nearly 40 years

have thrown parts of Africa into one
of the worst droughts in a century.

Across the planet, our once
stable climate is changing.

Weather is less reliable...

and is getting more extreme.

Wildfires are becoming
more frequent.

Droughts are more intense.

And storms are more ferocious.

All this from a recent rise
in global temperatures

of just a single degree Celsius.

Yet if climate change
continues unchecked,

we may see a rise of almost five
degrees by the end of the century.

We can only imagine what
this will do to our weather.

There are a few things more daunting
for the wildlife film crew

than the prospect of finding
a very rare animal in a vast area.

But that is the mission
in Mongolia's Gobi Desert -

to film an animal
numbering less than 500

in a wilderness of
half a million square miles.

We're all loaded up. We got 40 cases
of gear, we got nine vehicles.

We're off,
we're heading to the Gobi.

From the capital, Ulaanbaatar,

it'll take the team
five days to cross Mongolia

in the depths of winter -

travelling in a convoy
of large camping trucks,

home for the next five weeks.

1,000 miles later, the convoy
reaches the Gobi and makes camp.

Well, we have woken up
on our first morning,

and it's about an hour-and-a-half
before sunrise,

and rather foolishly we let the
fire go out last night, so it's...

..a cool minus 20 in here.

Everything's frozen solid -
toothpaste, hot sauce for breakfast,

even the AP's pee bottle...

..so that's nice.

Finding a scarce animal in
an area the size of Belgium

is clearly no small task...

but impossible without
the help of local researchers.

Each day, the team scour
thousands of square miles.

It's a huge area,
and there's only 450 camels,

so it really is a bit like
a needle in a haystack.

A truly enormous haystack.

450 camels...

28,000 square miles.

Easy, yeah? Yeah.

And when scanning the
horizon for camels,

mistakes are all too easy.

Another bush.

A bush. Sorry.

Sometimes there's not
even a bush to look at.

See anything? Nothing.

Another hill climbed.

Another trail followed.

Another dead end.

Thankfully, the experts
remain positive.

I hope you can see them soon.

Yeah, yeah. Please.

Two weeks since leaving the UK.

I'm just hoping that we haven't...

been slightly
overambitious on this one.

Getting slightly worried it
might actually be impossible.

Hmm... Good support there, thanks.

Eventually, the team
spot their first camel...

..but, unfortunately,
it spotted them first.

Very far away.

Poaching has made the
surviving camels very nervous,

and once they start running
they can keep going for miles.

And when the winter winds kick off,

all signs of camel vanish.

So, for about the past 24 hours,
we've been experiencing

the Gobi winds. It's been gusting
up to 70mph hour all night,

and the temps have probably
been down to almost -50

with the wind-chill. We just have to
hunker down, we can't film in this.

When the gale eases,
the search reveals new hope.

We got a load of fresh
camel tracks here.

And all tracks head one way -

towards the even more remote
mountainous southern Gobi.

The team must decide
if they should follow.

Do you think that landscape
is likely to be better for us?

More camels and
closer encounters or...?

What's your gut telling you?

Because of the wintertime,

we need to see some snow... Mm.

To see camels.

To survive in this waterless desert,
the camels depend on finding snow.

So, with none in sight,

the team decide to try their luck
in the icy mountains to the south.

Sure enough, there's snow -

and lots of it.

But the larger camping trucks
struggle in the mountainous terrain,

and the team are forced
to go on without them,

leaving them somewhat more
exposed to the winter conditions.

It's been down to
-25 over the last week.

So very thin canvas tents
will be a whole new experience

in the Gobi Desert for us.

I'm wearing, currently,
two pairs of trousers, thermals,

thermals on top, two pairs of
jumpers, three coats, two hats...

So I THINK I should be all right.

You all right, Eddie?

Oh, I'm terrific, yeah.

Really terrific!

I'm all cosy.

I'm not. I'm cold.

Really cold!

As Adiya predicted,
with snow come camels.

The signs are everywhere.

But having travelled so far,

they can't risk anything
ruining this chance.

Camels don't seem
to like the cars so...

now we walk.

We've been walking for
about five miles now,

and hiking across this landscape,

it really does give you a new-found
respect for the camels.

We've seen some camels
way out on the plain here,

but in order not to scare them,
John's going to head out on his own.

Yeah, yeah, I can see him.
He's, um...

Going to south?

Yeah, he's going to the south,
he's just this side of the ridge.

The camels come to John.

They are? The camels
are coming to John?

Yes! Really?

Maybe grab the bags
and come down to where I am now

by these bushes, and we'll see if
we can't slip down into the oasis.

This is just amazing.
It's hard fought...

..but the reward is so worth it.

Because right now we're
about 100 metres away...

from some of the rarest and
hardiest mammals on the planet.

What a privilege.

The team film behaviour
very few people have seen.

Rare images of one of the world's
most endangered creatures.

Once widespread across Central Asia,

this uninhabited desert is
the wild camels' final home.

Were it not for Adiya's team, it
might have disappeared altogether,

but because of their work we may yet
save this icon of the Gobi.

Next time...

..oceans.

All marine life depends on the
continuous movement of water.

Our oceans are linked
by powerful tides...

..and where there are currents,

there is life.

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.