Original subtitles

On a river in the American Pacific Northwest...

...the yearly salmon run has collided with the modern world.

This floodplain used to be easy passage for fish on a mission.

But a road has turned it into a deadly gamble.

The salmon must take their chances...

...to reach their spawning grounds upstream.

They are driven by an overwhelming instinct

to swim against the current.

So they've just gotta go.

And where one succeeds...

others can too.

Millions of migrating salmon must today run a treacherous gauntlet.

From the open ocean...

...inland past tarmac, concrete, and steel...

...these determined travelers will stop at nothing to reach their goal.

If they succeed,

their migration will bring a pulse of vital nutrients in their bodies

that nourishes a vast forest network that spans the Pacific Northwest.

To stay healthy,

this forest and everything that depends on it...

...needs its fish.

And these heroic salmon

are just one in a cast of incredible creatures

all over the world...

...whose battles to survive...

...adapt, and reproduce

also have the power to help nurse our ailing planet back to health.

They are our most powerful allies on the Earth's road to recovery.

While they fight for their futures,

they are in fact fighting for ours.

Humans.

We've done some strange things to this planet.

By attempting to build our dream homes...

...we've created a confusing world for the neighbors.

Wherever we've spread,

the dangers we've introduced are causing havoc.

But one creature has been preparing for the worst...

his entire life.

Hunkered down in his Florida bunker...

the ultimate doomsday prepper.

Inside a rock-hard shell six feet underground.

Now that's how you stay safe.

But even a recluse needs to eat.

For a gopher tortoise, leaving your burrow may well be daunting.

But to find fresh shoots, he needs to come out of his shell

and out of his comfort zone.

Come on, how scary can it be?

Here goes nothing.

The neighbors seem pretty harmless.

All busy keeping Florida's longleaf pine forest in tip-top condition.

Pollinators.

Tree planters.

Even pest controllers.

But it's best to give some a wide berth.

For our play-it-safe tortoise,

coming out of his shell seems to have paid off...

...with a midsummer feast.

But he can't let his guard down.

Because high summer is also

wildfire season.

It's nature's way of making space for new life to grow.

If he can't get back to his burrow,

he'll be cooked in his own shell.

Time to put the pedal to the metal.

Burning at over 600 degrees...

...the fire claims an acre every ten seconds.

Amazingly...

the tortoise has survived.

But how?

He didn't make it home.

But he has dug safety bunkers all over this forest.

And his doomsday prepping hasn't just saved his own skin.

Over 300 different species seek shelter from summer wildfires

in the burrows of gopher tortoises.

He has saved his neighbors.

And as each animal plays its own role in the forest,

together they'll help their home to recover.

We will increasingly rely on heroes like him

as the web of life on which we all depend...

...is threatened from all sides.

In 2020,

Australia suffered its worst ever bushfire season.

One-fifth of all its forests turned to ash.

Three billion animals killed or harmed.

But there may yet be a way to heal this broken land.

A flying fox descends on Downtown Sydney...

...with thousands of other fruit bats.

Her forest destroyed, these refugees are trying to survive in a new home.

This world is like no forest she's ever seen.

A canopy of concrete.

Electric branches.

Razor blade undergrowth.

Nothing in 50 million years of evolution has prepared her for this.

But she's learning fast.

And pinpoint night vision helps her find food

even in the heart of the city.

She must eat her fill before dawn.

Because after the night shift, she's got a day job to clock on to.

In a park nearby,

what used to be a rest stop for migrating bats,

has now become a permanent roost.

Hiding something truly precious...

her hungry baby waiting for his morning milk.

But the day shift brings its own challenge.

Heat.

Sydney summers now regularly top 110 degrees.

Far hotter than shaded forests.

And deadly for young bats.

But mom has some neat tricks up her sleeve.

Blood flows through the thin skin of her wings

so she can try to cool down.

And she can fan her pup.

But the temperature is still rising.

He's in trouble.

She must find a way to cool him down.

There's one thing left to try.

Water.

It calls for a daredevil descent.

The airspace is crowded...

...with fierce competition.

But it's nothing she can't handle.

A single dip soaks her fur.

Enough water to cool her pup...

...with a soggy, life-saving embrace.

Whatever this hostile place throws at her, she will do her best to find a way.

And there's more than just her baby's survival at stake.

Because fruit bats have the power to shape the world around them.

Amazingly, each flying fox can pollinate 50 different species of tree...

and spread thousands of seeds in a single night.

Even here in Sydney's parks,

there are signs that they are nursing nature back to health.

Over time, if these bats can return to their wilderness home...

...this vast tree-planting air force...

could help regrow their lost forest anew.

The healthier the Earth's wild places,

the harder they work to the benefit of us all...

...protecting the air we breathe and the water we drink.

The future health of our entire planet

may rest with nature's last great strongholds...

...and their most important inhabitants.

This grandmother has a growing family to support.

Every new baby, a blessing.

But also another mouth to feed.

Forest elephants have demanding nutritional needs.

And there's only so much grass you can stomach.

So, it's just as well she has Africa's biggest drugstore

right on her doorstep.

The Congo rainforest.

Bulldozing their way through the dense undergrowth is slow-going.

But there's a quicker way.

A path.

Generations of her ancestors have walked these same routes...

creating thousands of miles of elephant-sized corridors...

...making it far easier to browse the aisles.

And this path leads...

...to a forest pharmacy.

The clay is rich in salts and minerals...

that help them survive the sweltering heat.

Like an isotonic mud drink.

But to grow big and strong, this family needs fresh vitamins.

And Grandma knows every trick in the book to find them.

Elephants can hear some of the lowest frequencies

of any animal.

And they can even use the sensitive pads of their feet

to pick up the faintest of tremors.

And that is the sound of fresh fruit hitting the shop floor.

Grandma has a bearing...

and she knows the quickest route there.

And in their quest for a healthy diet,

wherever this family roams,

they also boost the forest's health.

Each elephant spreads over 200 pounds of mineral-rich compost...

...and weeds out several miles of choking undergrowth...

...every single day...

...which gives the forest's slow-growing saplings

the chance they need to transform into giants.

Giants with the power to help save us all.

As humans drive up the amount of carbon dioxide in our atmosphere,

this mighty elephant-grown tree is drawing it down.

It then performs one of nature's greatest magic tricks.

Transforming carbon dioxide into sugars

through the power of sunlight on its leaves.

Locking planet-warming carbon safely away

into its branches, trunk, and roots.

The work of gardening elephants allows Africa's tropical trees

to draw down an extra billion tons of carbon every single year.

These giants could help us turn the tide on rising carbon dioxide levels...

...and actually fight climate change.

While Grandma simply searches for what she needs

to keep her family healthy.

But in the last 30 years,

we have lost three-quarters of Africa's forest elephants to poaching.

With so little of our planet's wilderness still intact,

we need its wildlife now more than ever.

Nature's greatest healers are disappearing on our watch.

Species that do most for our planet's health

are amongst those most at risk of extinction.

And as everything is connected to the vast web of life,

their fate could soon become ours.

But what if we could help some of these vital animals...

to rise again?

Saiga antelope.

They once roamed the steppe from Europe to China in their millions.

Grazing and spreading seeds,

these nomads maintained the world's biggest grassland

for millennia.

Until the 1990s,

when rampant poaching devastated their herds.

Their numbers fell faster than any mammals in history.

And as the grazers disappeared,

so too did the grasslands that depended on them.

But a decade later, saiga hunting was banned throughout their range.

The future of the steppe rested on whether a few survivors

could come back from the brink.

A new hope.

And one becomes three.

Tomorrow's grazers ready to roam.

And thankfully, they are not alone.

Other saiga mothers have gathered at the nursery grounds.

At a year old, they give birth to twins,

and even triplets.

So with each yearly baby boom,

the herds nearly double in size.

In just 20 years,

a few thousand survivors have become a force a million strong.

This new generation is ready to reclaim their ancestral home.

Marching for thousands of miles every year.

Breathing life into the grassland wherever they spread.

And securing the future of the steppe for everyone who lives here.

Scientists have calculated that supporting the return of just 20 large mammal species

could help revive nearly a quarter of all the land on Earth.

So today, a movement is gathering pace across more than 70 countries worldwide...

to hand damaged landscapes back to their natural caretakers

in a process called "rewilding."

In Argentina's IberáWetlands, over a million acres of swamps, forests,

and grasslands once thronged with over 4,000 species.

But centuries of cattle ranching drove out the wildlife

leaving this rich tapestry at risk of collapse...

...until the turn of the millennium...

when work began to hand this land back to nature.

But now, one species is standing in the way of complete recovery.

With the cattle gone, clans of capybara are filling the vacuum.

Hundred-pound rodents...

mowing down any new shoots that try to grow.

Which means Iberá's recovery has hit the skids.

Not that these giant guinea pigs seem worried.

They're so laid back...

...they're horizontal.

But all that is about to change.

This pen holds one of South America's most feared predators...

...hunted out here over 70 years ago.

This rescued jaguar could solve the capybara conundrum.

While her challenge is feeding her twin daughters.

Everything now hinges on whether this killer can learn to hunt...

...on the other side of the fence.

The first free-roaming jaguars to set foot here since the 1950s.

It's all theirs for the taking...

if Mom can just tune into her killer Instinct.

Stealth mode.

Keep low.

Get close.

Then wait for your moment.

These capybara have only ever danced to their own tune.

Until now.

Her daughters witness a masterclass

and share the spoils.

They too will become agents of change...

...unlocking the full potential of this vast landscape.

This family of assassins will now bring fear wherever they tread.

The capybara will keep to the waterways where they feel safer.

Keeping grazers on the move gives more plants a chance to recover...

so pockets of new habitat can emerge.

And even more species can return to this old cattle ranch...

...building their own connections, making it more resilient to change.

Iberá's restored webs of life

will help it endure long into the future.

Thanks to the return of one missing piece of the puzzle.

Empowering nature's healers

can protect us from many of the perils of a changing planet.

Wildflower meadows boost bee populations...

...helping secure a quarter of our food supplies

from increasingly unpredictable seasons.

Protecting sea otters revives kelp forests...

which shield coastlines from increasingly stormy seas.

And rising whale numbers fertilize the oceans,

helping to feed blooms of plankton

that capture ten billion tons of carbon every year.

As much as all our rainforests combined.

When we help nature, nature helps us.

The signs of a hopeful recovery are there to see.

Across Washington State,

the paths of the mighty salmon run are blocked

by more than 10,000 man-made obstacles.

Numbers of some salmon species have crashed by up to 95%.

But as we begin to see the bigger picture,

today on one river...

things are about to change.

A campaign to tear down old dams

is transforming waterways across North America.

So far, over 1,900 have been dismantled.

Thousands of miles of rivers can once again run free.

So too can their salmon.

Finally, they can reach their ancestral spawning grounds.

As they lay their eggs in the cool, shaded streams...

their journey is complete.

But their legacy will endure.

An entire generation of salmon give up their bodies.

And their death pumps life back into the forest.

This vast transfer of nutrients from ocean to land,

from one life to the next,

is the forest's lifeblood...

providing up to 80% of the nitrogen it needs to grow.

The salmons' offspring will travel downstream

to start their cycle anew.

With our help, their numbers could flourish again,

sustaining an entire web of connections...

from mountain...

...to sea.

Bringing new hope for everyone that relies on them.

Nature can help heal our world...

if we just give it a chance.

Every living being is an invaluable link in the web of life...

on which, ultimately, we all depend.

In our connected world, every action has consequences.

And the choices we make

really matter.

Armed with new knowledge,

we can take steps to help nature nurse our planet back to health.

The time to act

is now.

Because it's no longer just a case of whether we can still save nature,

but whether nature can still save us.