Original subtitles

A hungry hunter...

with his eyes on the prize.

But whatever he tries, he's just not fast enough.

It's as if the dragonfly can see him coming in slow motion.

And maybe he can.

Dragonflies' food is tiny and quick.

But unlike the frog...

nine strikes out of ten,

he gets a meal.

Because his visual processors work five times faster than ours

and effectively slow down time.

The frog won't stop trying.

Close...

but no cigar.

The dragonfly isn't just keeping an eye on his slow-motion stalker.

He also has to defend his territory from rivals.

With his eyes on the skies,

he is less likely to spy someone hiding below.

The frog may not have the dragonfly's lightning moves,

but this time, he's right on cue.

A sense of timing is crucial to survival throughout our webs of life.

Nature works best when it's in sync with the planet's rhythms.

To make the most of it, life must time its opportunities to perfection.

Sometimes in milliseconds.

Sometimes across millennia.

Late afternoon in the Kalahari.

A lioness has hungry mouths to feed.

Her growing cubs need fresh meat every two days.

There's food everywhere.

But most of her targets are faster than she is.

Chase them around under the blazing sun,

and she'll quickly overheat.

She needs to get close enough for an ambush.

Tricky in broad daylight.

Her prey are primed to spot movement.

And once her cover is blown,

she's much less of a threat.

But she's not fully committed yet.

Because she knows the tables are about to turn.

As the sun sets, the odds shift in her favor.

She's harder to spot...

...less likely to overheat.

And her night vision comes into its own.

A herd of buffalo.

Five times her weight,

these armored giants are a dangerous target.

But if they haven't seen her, then she has the edge.

She targets a calf.

Weaker, less risky.

In the twilight, she makes it look effortless.

She has already cashed in on the advantage that dusk brings.

And her cubs will feast tonight.

The sun is always setting somewhere on Earth,

creating an endless beat of changing fortunes.

But our ever-spinning planet gives us more than just day and night.

Because the sun's power isn't the only force

that holds sway over life on Earth.

The moon carves its own path through the night sky,

pulling our oceans into a watery waltz.

And sea creatures must dance to its tune.

In Northern Australia, the tide recedes.

Beneath the mangroves, a new world appears.

Home to a banana fiddler crab.

He lives his life in the windows between the high tides.

So he's on a tight schedule.

Time to feed as fast as he can...

while his female neighbors go double-time.

His banana claw might be slowing him down now,

but when the moon is right,

his time will come.

The tide turns, and it's back to his burrow.

The cycle repeats.

But as the month moves on, the moon's pull on the ocean weakens.

Each high tide covers less of the beach.

Until eventually... for a few days...

his burrow won't get covered at all.

Now he's got one of the best spots on the beach.

And another male wants in.

Bananas at the ready.

In a shoving contest,

there's not much between them.

But when it comes to the grapple...

our champ's got the upper claw.

Go find your own burrow.

But time and tide wait for no crab.

He's got to find a mate.

A quick preen and he is ready to show off his winning claw.

But in which direction?

The beach is covered in crabs.

And he's not great at sizing them up.

How about her?

He's not her type...

of crab.

Ah...

Time to claw back some dignity.

She is more like it.

But now he's got competition from all sides.

He tries to tempt her with a wave.

But they all know that trick.

What if he goes a bit higher?

They do too.

Another and another.

It's turning into quite the beach party.

How's a girl to choose?

Finally, she selects the best banana on the beach.

And only just in time.

He seals her in his burrow before the tide returns.

She'll release her larvae on the next full moon...

when the strongest ebb will carry them far out to sea.

A lucky few will survive.

The rest provide a pulse of food to the ocean,

connecting whole webs of life to the never-ending rhythms of the moon.

But our planet has another cycle that shapes nature's networks in a slower

but perhaps more profound way.

The precession of the seasons.

A yearly pulse that life must adapt to.

With Earth's longer time scales, the stakes get higher.

Because when opportunities only come around once a year,

you've got to grab them while you can.

On Norwegian tundra...

...an old warrior watches over the herd.

The females will be in season for just a few weeks.

His only chance to father next year's calves.

Other males will want to stake their claim.

So each year,

this musk ox must face a ritual tournament to retain his crown.

A rival.

For the king, the gauntlet has been thrown down.

He puts up a front.

It's an old trick to psych out his opponent.

But the challenger doesn't back down.

They walk in parallel, hoping their size will scare the other off.

Not this time.

An airbag beneath their armored horns cushions them from an impact...

...as violent as a car crash.

The king is a veteran of many battles.

He uses the slope to make the most of his weight.

As he tries to gouge his opponent, he loses the upper ground.

Not for long.

This time, experience wins the day.

There will be more jousts to come in this annual tournament.

And only if he can win them all

will he secure his position for another year.

Now, all across the Northern Hemisphere, winter closes in.

In this harshest of seasons,

everyone must bide their time.

Resources freeze.

Temperatures plummet.

And life is held in suspended animation.

The only certainty of winter is that in time, it will draw to a close.

The earth's yearly journey around the sun

brings the Northern Hemisphere back into more direct sunlight.

Longer days return.

And winter yields to spring.

This is the season that life makes its own.

All powered by the growing warmth of the sun.

Seedlings race for their place in the strengthening light...

...each with its own strategy to get ahead.

Leaves sprout and unfurl.

Each one, a natural solar panel, harnessing the sun's energy...

drawing in carbon dioxide and converting it into food to grow.

So many plants come to life

that the planet seems to take a deep breath in.

Carbon dioxide levels dip dramatically,

helping bring balance to the atmosphere we all depend on.

The changing season triggers countless creatures to move north

as nature's networks spring back to life.

Billions of birds flock towards distant breeding grounds.

Ocean giants travel thousands of miles in search of food...

...while huge herds surge across the waking landscape.

To succeed, all of these heroic journeys must be timed to perfection,

even those of the most miniature migrators.

As the last snow melts deep in the forest,

pools appear.

In just a few weeks, they'll dry out in the heat.

By the time one creature wakes from her winter sleep...

a countdown has already begun.

This salamander needs to reach her pool and complete her breeding cycle

before the water disappears.

The first spring rain...

is the starting gun for the race of her life.

In salamander speed,

she's sprinting.

Her ancestors followed the same routes through the forest.

But times have changed since they first walked the Earth.

In a few hours, she's almost at the finish line.

The pool where her own life began.

Now she needs to find a mate as quickly as she can.

Other salamanders have also raced to this pool.

And they may just have a trick to help them with their speed dating.

In the forest shadows, mostly blue light penetrates.

Their vision is particularly sensitive in the twilight.

And in this blue hue, their bodies begin to glow.

Scientists have only recently discovered this phenomenon.

Could it be that it helps in their race to find a mate?

Now she can lay her fertilized eggs.

But time is already working against the next generation.

They need to hatch and finish developing...

before their pool disappears.

And it's already started shrinking.

Every spotted salamander's life is hurried by the ticking of the seasonal clock.

So too are countless other creatures.

Their lives tied to the rhythms of the earth, moon, and sun.

But some mysterious beings dance to their own beat,

keeping time not in seasons, but in decades.

Inside a maple tree, sap flows for the first time since last fall...

kick-starting new growth.

But deep below ground, one creature is using this pulse

to count the passing of the seasons.

A periodical cicada.

She feeds on the tree's sweet sap.

So as it rises each spring, she can tell that another year has passed.

She burrowed underground 17 years ago.

Now she's tunneled to the surface,

ready for the moment she's been waiting for.

As darkness cloaks this Indiana woodland,

things are about to get strange.

Aboveground, she's vulnerable.

But she's timed her emergence to perfection.

There's safety in numbers.

Billions of cicadas have synchronized their 17-year life cycle.

Like a zombie horde, they rise in unison.

Safely off the ground,

they begin the next stage of their resurrection.

An eerie transformation

into their adult form.

For the first time in 17 years,

dawn breaks to a chorus of cicadas almost as loud as a chainsaw.

The neighbors barely know what's hit them.

The last time these insects appeared was long before they were born.

It would be terrifying if they weren't so tasty.

For the next few weeks, this banquet puts meat on everyone's menu.

But with more than a million in a single acre...

the diners barely make a dent in the buffet.

So the risen can finally achieve their purpose.

They mate, and the females lay their eggs.

It's their final act.

Within a matter of weeks, all that's left are husks.

A massive dose of fertilizer,

pulsing life back into nature's underground networks.

Why 17 years?

We still don't really know.

But this pattern evolved deep in the past

when a long life cycle may have helped to survive more frequent cold snaps.

Because our planet also has climatic rhythms

that span tens of thousands of years.

Far beyond any living creature's sense of timing.

But the slowest changes can have the most profound effects on life.

For better and for worse.

The Sahara Desert, as large as the United States

and one of the harshest environments on Earth.

If you're not adapted to the heat, you won't survive.

This light-footed agama lizard

is small enough to find shelter.

And his scaly skin keeps much-needed moisture locked in.

But even he needs to drink sometimes.

Fortunately for him, even in this barren wilderness,

there is water.

A miraculous oasis for weary desert travelers.

But it might not be as welcoming as it seems.

Incredibly, this pool is full of crocodiles...

in the middle of the desert.

A hundred miles from the nearest flowing water.

While their far-flung relatives swim through lush swamps,

these crocodiles are trapped here.

For them, it's not an oasis,

it's a prison...

...where every inmate must fight for themselves.

There's fierce competition for anything that moves.

A migrating honey buzzard stops to drink...

...and wades in to cool off.

It won't feed everyone.

If they stay here, they could starve.

But if they make a break for freedom...

It's a desperate dilemma as their world shrinks around them.

But the fact they're here at all is a sign of a rhythm measured in millennia.

Because it wasn't always like this.

Just a few thousand years ago, this desert was green and fertile.

Crocodiles swam in flowing rivers.

Because our spinning planet has a long-term wobble

that repeats over millennia,

moving its hemispheres closer to and then further from the sun,

and altering our climate as it goes.

On its current path, the West African monsoon weakened,

and rain stopped falling in the Sahara.

Within just a few hundred years, the crocodiles' lush swamps

became one of the planet's largest deserts.

But even in today's searing climate...

there is still an echo of the long-lost past.

Just a few precious days of rainfall each year.

This briefest of wet seasons lets us travel back in time...

to glimpse what life was like here 10,000 years ago...

in a green Sahara.

If the inmates can cling on, in another 10,000 years or so,

the planetary wobble will run full circle.

Water will flow again,

freeing their distant descendants to reclaim long-lost rivers.

The creeping pace of our planet's slowest rhythms

makes them almost impossible to see.

But if these rhythms are interrupted even by the smallest increment,

we can start to see things change before our eyes.

Autumn in Oregon's Cascade Mountains.

This hare is trying to stay out of trouble.

With good reason.

Hares rarely die of old age.

A hunting goshawk will spot anything that moves.

So the skittish hare freezes.

Barely even breathing.

Hidden in plain sight.

The hawk moves on,

and the hare can breathe a sigh of relief.

But her home is about to transform beyond recognition.

If your best bet for staying alive is camouflage,

how do you cope when your world suddenly changes color?

You change too.

As the winter days shorten, she molts from brown to white.

An incredible costume change.

Once again, all she has to do is freeze.

And like magic,

she vanishes.

But now, a new threat.

Man-made climate change means that some winter days

are unseasonably warm, and snow cover can disappear overnight.

Her color change is triggered not by temperature, but by day length.

And these warmer days are still short.

So now, she's desperately out of sync with her surroundings

and an easy target.

Time for plan B.

Speed.

She's lost him.

But when you're this conspicuous, staying hidden isn't an option.

Next time, she may not be so lucky.

Mismatched hares are more likely to be picked off.

And now they're out of step more often.

Her kind could still have a future in this changing world.

This snowshoe hare has adapted to stay brown all year round.

So his life is easier when snow is thin on the ground.

The future of their species may depend on more guys like him.

Nature works best when life keeps step with the planet's many rhythms.

So what happens when human activity disrupts the tempo?

As the world changes suddenly all around us...

can nature survive...

...the coming storm?