Original subtitles

A jagged maze of rock and ice...

...where temperatures plunge to 40 below...

and brutal blizzards dump 30 feet of snow.

Winter in the Rockies is not for the faint-hearted.

But for one creature...

...it's the challenge he's built for.

Where we see treacherous slopes,

this wolverine sees a playground.

His thick fur sheds snow like a winter jacket.

His claws dig in like climber's crampons.

He plows through the most punishing winters...

with just a carefree shake of his coat.

But mountain solitude has its downsides.

There are few other animals around.

And for a hungry meat eater, that is a challenge.

He treks up to 20 miles in a day...

searching for a meal above...

and below the snow.

But he needs to keep an eye on the skies too.

Because the peaks above hold a deadly threat.

After months of heavy snowfall, the mountain is about to unload.

A deluge of frozen violence.

Over three million cubic feet of snow and ice...

thundering down its peaks...

at up to 100 miles an hour.

For pretty much any creature caught in its path,

the roaring snow...

...is the sound of death itself.

But for this lucky wolverine, it's a dinner bell.

He locks into a scent

and sets to work.

An avalanche may be bad news for an unlucky mountain goat...

but it's just what a hungry wolverine has been counting on.

Disaster for some...

is salvation for him.

Because life doesn't just need our planet's soft side.

It also relies on its rage.

The most destructive forces on Earth

are the same forces that bring our planet to life.

Volcanoes are great destroyers.

But they also release vast amounts of steam.

So much so that our oceans are now filled with water

once locked in the Earth's interior.

Their lava cools to create new land.

None more precious than volcanic islands.

These remote archipelagos churn the ocean's currents,

drawing up nutrient-rich waters from the deep,

igniting an explosion of life.

Both above...

and below the waves.

Volcanic islands form oases of life in the Big Blue...

...for those who know where to find them.

This young hammerhead is on her maiden voyage,

traveling hundreds of miles from her coastal nursery

out into the vast Pacific.

She might not know where she's heading...

but she has a guide.

Her strange snout bristles with receptors

that can detect the magnetic signature of the volcanic seabed.

Cooled lava signposts her way across the ocean.

She only has to follow her nose

and let instinct lead the way.

Cocos Island,

the peaks of an ancient volcano rising 12,000 feet from the ocean floor.

And to her senses,

it lights up like a magnetic beacon in the wilderness.

After a 300-mile journey, she's earned a pit stop.

So she sets her sights on one particular Cocos resident.

But the shark isn't browsing the buffet.

She's serving the snacks.

Her first ocean voyage has left her riddled with parasites.

Clouds of butterfly fish pick them off and clean up her infected scars.

Their nibbles are like a mini massage,

keeping her calm while they feed and help her heal.

And it's a timely service

because this volcanic wonderland isn't just a shark spa.

Other travelers have been drawn to this special meeting place...

forming a circling school hundreds strong.

Scientists suspect that this gathering is like the hammerhead summer ball...

where they relax...

socialize...

and if they're lucky, find a mate.

As this debutante joins the dance...

it could be the start of a new journey

towards motherhood.

A journey made possible by underwater volcanic trails

millions of years in the making.

Our oceans are still home

to some of the planet's most violent natural phenomena.

The sun's energy burns most fiercely in the tropics

where much of its heat is absorbed by the ocean.

But these warming seas have a release valve.

Transferring their energy into the sky, they vent their excess heat

by feeding the most devastating storms on Earth.

Hurricanes.

This growing monster

will transform the lives of all those caught in its path.

In a Miami park,

one of America's most fiercely territorial creatures...

...is marking his turf.

Anole lizard.

Tough guy.

His push-ups show off his strength,

warning his rivals to keep off his tree.

So he gets more food and more females.

But not everyone is getting the message.

An intruder...

with his eye on the tough guy's tree.

Has he got the moves to muscle in?

Not bad.

The tough guy needs to show him who's boss.

Behold.

The ultimate lizard power move.

But two can play at that game.

There's only one way to settle this.

But while they do battle...

the mega storm is closing in.

They bolt for the treetops...

to escape the inevitable flood.

As the storm makes landfall...

anole lizards cling to high branches.

Lose their grip,

and they lose everything.

The tough guy's future hangs by a fingernail.

And his rival is struggling too.

The champ has kept his grip and his territory.

In this battle...

only the strongest survive.

But it's a fragile victory.

Today, man-made climate change is making hurricanes stronger

and more frequent.

Faced with this growing rage, these lizards' bodies are changing.

Remarkably, over just a few generations,

they've evolved larger toe pads to help them keep a stronger grip.

Where a warming climate will leave these creatures, we don't yet know.

But we do know that it is pushing our weather to even greater extremes.

While some places drown, others scorch.

Growing deserts are changing the face of entire continents.

All life must adapt

or die.

West Africa, south of the Sahara Desert.

The wet season has grown erratic and unpredictable.

Daytime highs of 110 degrees...

transform this thorny scrub into an open-air oven.

Wildfires rip through the landscape...

leaving blackened skeletons in their wake.

But one group won't give up on their old home.

This baby is growing fast.

So she's always hungry.

And if anyone can find food in this wilderness,

it's her clever family.

There's a knack to extracting the seeds from a woolly kapok fruit...

even if they are a little dry.

To survive here, she must use that big brain of hers.

She learns by example.

A promising student...

but still working on the basics.

Knowledge and skills passed down through generations

have helped these survivors cling on even in this desiccated landscape.

But the one thing they can't do without

is safe drinking water.

And the most important lesson is where to find it.

The riverbed is bone dry.

They may know where the best fruit still grows,

but even her family can't magic water out of the ground.

But grandma has roamed these plains for 40 dry seasons.

If anyone can lead them out of this, it's her.

And the family falls in behind.

Their home is drying out.

Habitat loss and poaching have seen this species decline by 80%

in the last 30 years.

Today, survivors need to be smarter and more adaptable than ever.

Grandma leads the troop to a water hole that hasn't failed her yet.

But even this reliable oasis has dried to a stagnant pool.

The water is undrinkable.

Grandma digs a hole near the edge of the pool.

It starts to fill.

Water filtered clean by the sand.

The family joins in.

Grandma's wisdom has saved them.

And baby has learned another crucial lesson for her future.

As this part of Africa dries out...

it has consequences for life far beyond.

Even on the other side of the planet.

As deserts grow,

they can pump ever more dust and sand into the atmosphere...

where high-altitude winds carry it into weather systems

that spread across the globe.

Towards the poles, it settles on glaciers and ice caps.

Dulling their sheen,

absorbing more solar radiation...

and warming up their icy surroundings.

The world's largest land predator

has spent a hungry summer foraging along the shoreline.

Now the season is changing.

He checks out the sea ice.

He can only reach the seals he'd rather prey on

when it freezes hard enough to support him.

But this autumn is warm.

And the sea ice is late.

And he's not the only one hungry for the chance to hunt.

Hundreds of polar bears gather on Canada's northern shores

to wait for the freeze-up.

For a curious adolescent,

it's an irresistible chance to test his strength.

Either of these thousand-pound heavyweights

could land a fatal blow...

...if they were fighting for real.

Sparring kills some time,

but he's still hungry.

There's only one place left where he might find something to eat.

He turns his back on the sea and heads the other way.

Inland.

Towards the forest.

Who knows what he might find here?

Wolves.

Pack hunters.

They rule the northern forests.

Patrolling their thousand-square mile territory every day...

in search of food and intruders.

Wolves and polar bears do not usually cross paths.

But today, encounters are on the rise.

A lone wolf is no match for a bear.

But the pack is closing in.

Who's top dog now?

Are you a meal...

...or a mortal threat?

There's easier pickings to be had elsewhere.

By standing his ground, this intrepid bear wins the day.

Forced to spend more time away from the sea ice,

polar bears must figure out their place in a strange new world.

His gamble in wolf territory has paid off this time.

An abandoned moose carcass.

Enough food to keep him going until the sea freezes again.

But not all creatures have the skills to keep up with their fast-changing world.

Climate change is creating ever more extreme conditions,

breaking fundamental connections in the webs of life.

And it's causing havoc...

in ways that you'd least expect.

Deep in the heart of the Sierra Nevada Forest...

this pine tree is under siege.

Its foe,

a western pine beetle.

This tiny assassin searches for a weakness...

to drill in and lay her eggs.

If she succeeds, her hungry larvae will destroy the tree from the inside.

But this isn't just a tree.

It's a battle-ready fortress.

Behind its barricades flow hidden supply lines.

A hundred gallons of rain water pump from its roots to its crown every day.

And this water powers another line of defense.

Resin.

It flows to the breach.

And repels the invader.

She's programmed to keep drilling, and a bit of liquid won't stop her.

But the tree's resin...

has another trick.

As it dries,

it hardens.

Stopping even the most determined beetles...

in their tracks.

But the pines can't always mount such a powerful defense.

A changing climate is seeing Pacific weather patterns

shift to the north.

Storms that once rained on these Californian forests

now hit the Canadian coast.

In recent years, these trees received just two-thirds of the usual rainfall.

And without enough water to keep their resin flowing...

...the balance of power has tipped in the beetles' favor.

They breach the defenses...

and their larvae tunnel through the trees' supply lines...

cutting off the water it needs to survive.

It's the tree's last stand.

In a silent scream...

the forest is dying.

All it takes is a single spark.

A million acres burning at 2,000 degrees for months on end.

In some places more than 80% of the dead trees fueling these fires

is ponderosa pine killed by beetles.

But even as burning forests paint the San Francisco skies orange...

...the trees have a glimmer of hope.

They're starting a slow exodus northwards to safety.

Some at a rate of a mile every three years.

Pine trees now grow in latitudes once too cold for them to survive.

As the tree line moves north

it opens up opportunities for others to follow...

which could have surprising consequences for us all.

This pair of intrepid beavers are following the march of the trees,

pioneering further north than any other beaver before them.

As far as the Alaskan tundra.

And this new neighborhood now provides everything they need to get busy.

They must build their brand-new lodge and dam.

By tooth...

and by paw.

In just a few short months,

these meadows will be locked in the frozen grip of an Arctic winter.

To survive this far north, their dam needs careful construction.

Hold back too much water, and it could drown their lodge.

Too little, and their pond will freeze solid, trapping them inside.

It's a delicate balance of precision engineering

and furious gnawing.

And only the elements will decide if they've got it right.

Winter.

Has their lodge prevailed?

Or have they built their own icy tomb?

They've pulled it off.

A perfectly crafted home.

Fit for a new frontier.

Only when spring arrives do we see that their dam has had another effect.

Our beavers have turned their pond into a lake.

It absorbs the spring sun, heating up the frozen ground beneath.

As the soil thaws, more streams flow and more trees can take root.

A gold rush of building material

for more beavers moving up from the south.

Turning this virgin land into a bustling frontier community.

But this budding utopia isn't everything it seems.

Alaska's frozen bog land holds a dark secret.

As it thaws...

...it releases methane.

A greenhouse gas with the power to tip our climate out of balance.

It traps up to 80 times more heat in our atmosphere than carbon dioxide,

speeding up the thawing of underground ice.

Which can release still more methane

in a vicious cycle of ever-increasing temperatures.

Ninety percent of this excess heat

feeds back into our oceans...

...fueling more hurricanes,

and in some places, something far more insidious.

The legs of an abandoned oil rig

provide the perfect anchor point for this tiny polyp.

From its prime location...

it scopes out new spots

to deposit a clone.

In a warming ocean,

it doesn't take long for a single polyp to create a clone army.

But that is just the first step in their relentless expansion.

After a few short weeks, the clones start to transform.

Losing their tentacles and remodeling their bodies into tiny towers.

Each clone becomes a production line.

A conveyor belt of babies.

A warm and overfished ocean has fewer predators.

So these babies can survive in record numbers.

They grow to adulthood in just a few weeks.

Becoming jellyfish.

Without a shell or a skeleton, they can endure

even as a changing climate makes our oceans ever more acidic.

The planet's ultimate survivors.

And these simple gelatinous creatures will eventually produce more polyps,

each with the power to create its own army of clones, millions strong.

Our changing oceans are now bearing witness

to what some scientists call "the rise of slime."

Oceans of jelly.

Legions of rodents.

Swarms of insects.

All warnings that nature's network is at breaking point.

We are all starting to feel the knock-on effects.

But there are still ways to nurse our sick planet back to health.

We share our home with extraordinary species

whose struggles to feed their families...

save their children,

and protect their homes

can help nature's network to recover.

Our living world's most powerful healers.

They hold our future in their hands.