All language subtitles for 70039BD13696E369C91EC05D285E88D2_eng

Summer has arrived.

And what was paradise is no more.

The fresh water that flooded the delta…

only stays for a few months.

And water holes are now vanishing.

Fast.

This means only one thing

for the thousands of elephants
who've been living here.

It's time to move on.

This has been the only home
Metsi and Bosigo have ever known.

But in a few weeks,
all the water will be gone.

So they must leave the delta
with the rest of their family.

A herd of females,

sisters, aunts, and cousins,

led by their grandmother,

the great matriarch, Pula.

They're embarking on a journey
along with thousands of other families…

out into the desert…

in search of water.

For the next eight months,

they will migrate
from water hole to water hole…

and navigate ancient elephant trails…

…using the matriarch Pula's knowledge,

handed down to her through generations.

The trek will put all their lives at risk.

And they'll need
every one of their exceptional senses…

…to endure the dangers.

Making this journey is not a choice.

Without water, they will die.

Even on our blue planet,

fresh liquid water is scarce.

And if we search beyond the shores
of our own planet…

it's rarer still.

Even the most arid desert on Earth

is nothing compared
to the rest of our solar system.

In the cold outer reaches…

…the only surface water is ice.

Like Saturn's frozen moons…

where fountains of ice

shoot kilometers into space.

Closer to the Sun on Mars,

water is stripped away
by savage solar winds.

And on Venus,

it simply boils away.

There's only one world we know of

that has the gift
of liquid water on its surface.

A pale blue dot.

Our home…

where right now,

water is driving one particular family

on a quest for survival.

Just a month after leaving the delta,

only a scattering of muddy pools remain.

And they're getting fewer
and farther apart each day.

Pula is using her highly tuned memory
to lead her family to a water hole.

She can remember the exact route,

even decades later.

It's been a long day's march,

and all of them are desperate for a drink.

But so are the other 130,000 elephants

that live in Botswana.

The dry season has drawn herds
from far and wide…

…to this water hole.

All competing
for the same shrinking resource.

The adults teach the young ones
clever survival tricks,

like how to skim a muddy pool
to get the freshest water.

And how to use some muddy water
as refreshing sunscreen.

Their wrinkly skin is perfect
for trapping water and keeping cool.

But Metsi and Bosigo are also learning…

mud pools aren't just a place to drink.

They're water parks too.

With so many thirsty elephants,

the water hole has been drained.

Pula's family must press on…

and try to make it to the next water hole
before the blazing sun sucks it dry.

This battle between sun and scorched earth

has raged ever since our world was born…

when our blue planet
was anything but blue.

Four and a half billion years ago…

Earth was in its infancy.

A fireball of molten rock…

…destined to become a dry, barren world.

But millions of kilometers
out in the coldest reaches

of the solar system…

water crystals were forming

on the surface of dust particles.

Over time, these grains
of dust clumped together into asteroids.

Millions and millions of them.

And these became the asteroid belt.

A vast expanse of icy rocks.

Yet they've laid tantalizingly out
of Earth's reach.

As luck would have it, however,

a giant was on the move.

Young Jupiter.

A monster of a planet.

Forces within
the turbulent inner solar system

were slowly pulling it in toward the Sun.

A flight path that brought it
into a collision course

with the asteroid belt.

As it thundered through the asteroids…

…its massive gravitational force

flung rocks in every direction.

And yet,
from all this chaos and destruction

came the ultimate cosmic gift.

Icy, water-rich rocks
were hurled towards the Earth…

…bringing the promise of life
one step closer.

Over billions of years,

asteroids were woven
into the fabric of Earth as it formed.

Caught in the turmoil wrought by Jupiter…

…driven deep into the Earth by asteroids,

water molecules did not have
an easy journey getting here.

And they still had a long way to go,

imprisoned for millions of years,

locked within Earth's molten core…

waiting for another miracle…

to set them free.

Today, much of Earth's water
is still trapped underground.

So elephants have evolved special skills

to find it.

Even the muddy pools are empty.

This dry season
has become a full-on drought.

But Pula has a superpower.

Her incredible trunk,

packed with millions of sense receptors…

can smell water from kilometers away…

and pinpoint its sources deep underground.

But you have to dig for it.

Metsi isn't a big digger.

But Bosigo is a natural.

And Metsi is offered a seat at the bar.

These few sips won't last them long.

But if water
had stayed trapped in the Earth,

there would be none to drink.

There would be no elephants.

No life at all.

After water
was delivered here by asteroids

and consumed by the Earth…

it was locked into the rock as crystals

deep inside the planet.

It stayed buried for millions of years,

beneath a vast sea of magma.

Until slowly but surely, Earth cooled.

And its surface hardened to a thick crust.

Then, finally,
the boiling interior broke through.

Enormous volcanoes

blasted gas and vapor
kilometers into the sky.

At last, water molecules…

…were set free…

…and formed the first clouds.

Growing and building
for millions of years,

becoming laden with water…

…until the temperature
dropped just enough…

…for the very first raindrop…

…to form and fall.

What followed was a deluge…

that lasted thousands of years.

Puddles turned into rivers.

Lakes…

…became seas.

And great oceans flooded Earth's surface.

And here, water gave rise
to something magical.

The first life.

From these first cells

sprang every living thing.

Water is the fundamental ingredient

of every cell of every creature on Earth.

And today…

the herd still carries
this ancient water within them.

It transports nutrients and oxygen.

It powers every heartbeat.

And drives every breath.

Life evolved because of water,

which is why no life
can survive without it.

In Botswana,
the drought is only getting worse.

The elephants' world is on fire.

The herd manages
to escape the burning forest…

but walks straight into a new threat.

In this drought, everyone is suffering…

…from thirst and hunger.

And for lions,
baby elephants would satisfy both.

The adults rally around Metsi and Bosigo.

It's enough to keep the threat at bay.

But lions are patient creatures.

And the herd still has to cross
an unforgiving wasteland…

before the next water hole.

They need a lifeline.

And the Earth provides it

in the most unexpected of places.

The acacia tree is a beacon of hope.

And a haven for creatures of all kinds.

Its long roots reach
much deeper underground

than an elephant could ever dig…

…drawing water up to its branches…

and leaves.

It's just enough water to keep them going.

Especially vital for Metsi's mother,

still nursing her baby.

But this is so much more
than just a local oasis.

It's the vital link
in water's eternal cycle.

The acacia tree connects ground and sky…

…breathing oxygen and vapor into the air.

Feeding clouds

and powering water's journey
around the planet.

Ever since rain

fed the first green shoots…

and gave life to the first tree…

…plants have made our planet habitable…

…bringing a once barren ball of rock

to life.

But the gifts our universe bestows

can also be taken away.

A long time ago,

there was another planet

whose surface was covered in liquid water.

A water world just like ours.

The same forces
that delivered water to Earth

also gave it to Mars.

With an atmosphere in place,

clouds formed,

rain fell,

rivers flowed.

And an ocean surged across its surface.

It was a world of possibility.

It had the potential for life.

But it didn't last.

Because not far away
was a raging nuclear inferno.

Our Sun.

It unleashes torrents
of high-energy particles

so powerful and deadly…

…they can devastate planets.

This solar wind streams through space…

at 400 kilometers per second.

And it ripped through
the Martian atmosphere,

tearing water molecules apart.

Bit by bit,

over millions of years,

the planet's protective layer
was stripped away by the Sun's fury…

…until its ocean evaporated…

and its water was lost to space.

Mars became a desolate, frozen shadow

of its former self.

Consumed by dust storms.

Any chance of complex life…

gone forever.

This could have been our story too.

But somehow, on Earth,

water and life
have found a way to cling on.

In Botswana,

after 200 days in the burning sun…

…there is no water to be found.

Violent winds whip the scorched earth

into a dust bowl.

And the elephants' struggle
hasn't gone unnoticed.

In daylight,
adults can usually protect their young.

But when night falls…

…it's a different story.

Lions are masters of chaos and confusion.

They pick the most vulnerable target…

…working as a pack…

…until there's nowhere left to run.

Without the entire herd as protection,

the lions overwhelm their prey.

The drought and endless search
for food and water

have taken their ultimate toll on Bosigo.

Elephants form deep emotional bonds.

All the family mourn Bosigo's loss.

The herd gathers to comfort Metsi,

who feels it hardest of all.

The never-ending fight to survive

plays out every year,

across the Okavango…

across our planet…

and beyond.

But in this battle for survival,

Earth got truly lucky…

with a secret guardian that protects it.

Deep within…

…the planet's raging molten furnace burns

and churns…

…generating a powerful magnetic field

that extends from the heart of the planet…

…65,000 kilometers out towards the Sun.

A vital force field defending Earth…

…from the same savage solar winds

that stripped water from Mars.

Defeating them
before they hit our atmosphere.

Safeguarding our essential water.

Hugging every drop close to our planet.

This is what makes our pale blue dot

unlike anywhere else.

A place where life can thrive.

Bringing relief to the elephants.

Ensuring rains return each year
without fail.

In the distance,
storm clouds are building.

Elephants can detect
the low-frequency rumble of thunder

from 240 kilometers away.

And it's telling them it's time
to return to the Okavango.

From the highlands of Angola,

water is weaving its way through Botswana…

…to rejuvenate the delta…

with the kiss of life.

Every step
that brings the herd closer to home…

is a continuation
of a much larger cosmic odyssey.

From tiny molecules hitching a ride
on dust beyond Jupiter…

to surviving the crushing heat
of early Earth.

Imprisoned in the planet's core…

…then set free…

…to sow the seeds of life…

…every drop of water
has an amazing tale to tell.

Every molecule…

…a link in an unbroken chain…

…cycling over tens of thousands of years…

…through air…

oceans…

rocks…

…and elephants.

After eight months
and hundreds of kilometers,

Metsi and her family have finally reached

the life-giving waters of the delta.

It's well past time to drink…

and play.

And then, drink some more.

And show the newest member of the family…

…how they do things in the delta.

Metsi and her new baby cousin

are the latest in a long line

to benefit from water's miraculous arrival

on this planet.

They will forever be connected

to the universe

that gave our planet this magic ingredient

and gave us the ability
to preserve and treasure it.

Next, the story of our universe concludes…

…with the force that brings everything
we've seen so far together.

The great sculptor of the cosmos,

gravity.

It's a force of attraction
that built our planet.

And we'll bring two penguins together
at Earth's southern pole.

But when did gravity
start exerting its influence?

How does it create both order and chaos?

And why does it make ours
the perfect planet for life…

…and love?