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(Majestic music)

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NARRATOR:
In a realm of snow and ice...

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(Ice crackling)

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..water transforms into nature's
most powerful sculptor.

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From fragile snowflakes...

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to towering glaciers...

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..it shapes landscapes...

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(Low bellow)

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..and lives.

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Driving epic journeys...

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..extraordinary adaptations...

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..and crowning rulers.

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This is the magic...
of frozen water.

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(Waves crashing)

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Take a dive into our planet's
mesmerising world of water.

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(Epic music)

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From the monumental open ocean,

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to the rugged coasts
that serve as the dividing line

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between two worlds.

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From the changing rivers
that carve through continents...

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..to mysterious lakes and swamps.

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Immerse yourself in the magic
that unfolds...

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..as we reveal...

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The Secrets of Our Enchanted Waters.

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(Gentle music)

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Water shapes life
in the most unexpected ways.

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When seasons change,
and temperatures plummet,

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water takes on its mightiest
personal.

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Building frozen empires,

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and influencing everything
in its path.

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Water in its solid state
even has the power

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to create an entirely
new species

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and then turn it invisible.

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(Intriguing music)

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This female polar bear
is conserving her energy.

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She has thrived throughout
the long, dark winter.

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But now, as temperatures
steadily rise,

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her kingdom of ice
is disappearing.

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She needs to make the most
of the frozen water

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while she still can.

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(Water sloshing)

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Soon, the sea ice
will melt away completely,

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along with her hunting advantage.

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(Polar bear groaning)

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Even the greatest apex predators

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struggle to find the motivation
to get going.

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But her inertia
is not due to the cold.

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She was born
for these conditions.

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(Birds squawking)

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Her ancestors diverged
from brown bears.

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When a small population
was trapped in the north

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as the Ice Age descended,

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they had to adapt to survive...
and fast.

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(Inspiring music)

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Over the next 500,000 years,

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the frozen realm gradually
transformed those brown bears

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into the polar bears
that now roam the far north.

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The iconic Arctic residents
we see today

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are the result of one of the
fastest evolutionary changes

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amongst all mammals.

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To endure the deep freeze,

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wandering foragers
became masterful hunters.

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Forged by ice
and guided by instinct...

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lumbering land animals
were streamlined

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to fit their new
semi-aquatic lifestyle.

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(Water splashing,
polar bear groaning)

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(Gentle music)

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And to combat the cold,

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extra layers of fur grew with
a crucial additional feature.

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Each hair has a hollow core,
offering life-saving insulation.

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As a result, their ancestral
brown fur lost its pigment

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and turned translucent.

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Blending in seamlessly
with their winter wonderland.

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Now, having perfectly evolved
to a life in the Arctic,

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this polar bear needs the sea
to freeze over

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so she can use the ice as a platform

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for hunting her primary prey.

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But as it begins to fracture,

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just finding food
is a monumental challenge.

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She may have to swim hundreds of
kilometres in search of a meal.

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Until finally,
she picks up a scent.

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A bearded seal
hauled out on an ice floe.

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The melting ice means
her journey across the sea

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may be more unstable.

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But it also offers her
the opportunity for an ambush.

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(Water splashing)

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(Tense music)

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Her sleek shape makes her
an efficient swimmer,

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with her huge paddle-like paws
pushing her silently

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through the water.

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She can't risk being spotted.

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Her smooth movements
mimic the floating ice.

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Silently, she fully submerges
in the water...

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..and swims under the ice...

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..for the ultimate sneak attack.

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(Dramatic stinger)

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(Splashing)

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Even an ice queen
can't win every time.

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(Polar bear panting)

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With one shake of her
water-resistant fur,

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she'll be dry in no time.

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(Gentle music)

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Every failed hunt
costs her valuable energy,

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and time is running out.

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When summer peaks,
most of her ice will disappear,

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and she'll be forced
to return to dry land.

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Left to scavenge
whatever scraps she can find

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until the freeze returns.

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This seasonal thaw brings
hardship for the polar bears.

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But every year,
it is this great melt

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that breathes life
back into the Arctic,

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igniting an entire food chain.

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(Enchanting music)

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For much of the year,
the Arctic is a frozen wilderness.

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But beneath the ice
lies a hidden secret...

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waiting for the sun
to unlock its potential.

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After the darkness of winter,
spring approaches.

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It's still well below freezing,

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but the daylight hours
are getting longer,

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and the sun's force is increasing.

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Then a pivotal moment arrives...

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..and the balance is tipped.

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The sun's power becomes
just strong enough

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to set off a chain of events

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that will bring new life
to the Arctic.

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(Mesmerising music)

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Underneath the sea's
frozen surface,

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the ice has been stained green
by algae, a tiny marine plant

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that has lain dormant
throughout the winter.

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(Clouds whooshing)

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As the sun's rays start
to penetrate the ice...

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..it awakens the algae.

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Like all plants,

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they use photosynthesis
to turn sunlight into food.

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And now,
there's just enough of it

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to kick the algae into action,

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which in turn, stirs another creature
from its winter torpor.

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The Copepod.

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These tiny marine crustaceans,
just two millimetres long,

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rise up from the depths.

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(Water bubbling)

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Despite their diminutive size,

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these creatures are the key to
all life in the polar regions.

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They devour the algae
in their millions.

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This transfers the sun's energy
to the copepods...

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..where it's stored in their
bodies as a fatty oil.

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Now, locked beneath the ice
within the copepods,

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lies a store of
pure bottled sunshine,

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waiting to be released.

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(Joyful music)

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Above the water, the sun continues
to melt the surface ice...

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..slowly unlocking the pantry door.

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(Water sloshing)
Fish are the first to arrive,

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to feed on the abundant copepods.

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Followed by Arctic seabirds.

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(Birds squawking)

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(Majestic music)

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And then, the largest predators
join the feast.

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The sun's life-giving energy now
flows throughout the food web,

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all triggered by the Great Melt.

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This explosion of life
will fuel the Arctic residents

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during the summer months,

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until the big freeze returns

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and the waters
fall silent once again.

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(Sombre music)

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Frozen worlds can rise

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and fall with
the changing temperatures.

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(Snow pattering)

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But when the snow arrives early,

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being caught in last season's
wardrobe could be fatal.

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(Intriguing music)

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It's late autumn in Norway.

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Among the changing leaves
of the forest,

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this stoat is prepping
for winter.

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He doesn't hibernate

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but needs to store some
emergency rations, just in case.

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He has time.

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Highly attuned to the dwindling
daylight hours,

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his internal clock will warn him
when change is coming.

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(Gentle music)

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But this year, winter arrives
unseasonably early...

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..taking everyone by surprise.

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(Enchanting music)

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And it seems some creatures
like surprises.

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(Playful music)

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As fun as it is,
there is a problem.

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The early snow has caught
the stoat unprepared.

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(Ominous music)

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As he ventures out
to look for food,

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his brown fur stands
out against the white,

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making him an easy target
for his greatest foe.

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The golden eagle.

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He needs a costume change.

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Stoats have the remarkable ability

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to turn completely white in winter,

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to blend in with their
changing surroundings.

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But it's not the arrival
of snow on its own

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that triggers
the change in colour.

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It's actually
the length of the day.

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As the days shorten,
he produces more melatonin,

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which changes
the way his fur grows.

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(Stoat pattering)

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Meaning his transformation
is usually perfectly timed.

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(Curious music)

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But now, the sudden change
in weather

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sends the melatonin
within his body into overdrive,

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speeding up his moult.

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First, he waits for the thicker
white hairs to grow...

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..before he sheds
all of his brown fur.

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While he moults, he's neither
one colour, nor the other.

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So he needs to remain wary.

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Oops, still not quite ready yet.

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A few days later...

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..his makeover is complete.

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As white as pure snow.

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And hard to spot.

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He's even changed his name.

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Now, he's known as Ermin.

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He still has the black tip
to his tail.

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This acts as a useful decoy for
predators, so he's keeping it.

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Now fully camouflaged,

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he can safely continue
his search for food.

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Snow can influence coat colour
throughout the Arctic.

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But could winter white
be going out of fashion?

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(Gentle music)

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The ice worlds of our planet's
wild north have helped create

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one of nature's most charismatic
shapeshifters.

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The Arctic fox.

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Like the stoat,

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this female has already changed
her coat for winter.

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She is equipped for survival

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in the most changeable
of environments.

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As the frozen brown earth
of the tundra turned white,

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so did she.

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Becoming a ghost in the snow.

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(Wind howling)

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(Delicate music)

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The ice and snow have demanded
a thicker winter coat,

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00:18:46,360 --> 00:18:48,120
to protect her against
temperatures

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as low as
minus 50 degrees Celsius.

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(Harsh wind gusting)

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But winter brings
other challenges.

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The snow that conceals her
also buries her prey.

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Finding food beneath
layers of ice and snow takes...

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..a different approach.

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00:19:22,880 --> 00:19:24,840
(Wind whistling)

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No luck today.

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00:19:32,880 --> 00:19:36,120
But this hunter
is also happy to scavenge.

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The border where the tundra
meets the unfrozen sea...

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..brings new opportunities.

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(Waves crashing over gentle music)

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She scours the beach.

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The ocean never fails
to deliver tasty morsels

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to this shoreline,
whatever the season.

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00:20:06,920 --> 00:20:11,240
But she's not the only one
looking for leftover seafood.

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Another Arctic fox.

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A perfect shadow of herself.

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Despite the snowfall,
this fox never turns white.

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He's what's known as a blue morph.

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He's the same species,

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00:20:41,320 --> 00:20:44,760
but a genetic mutation means
his coat only ever turns

262
00:20:44,800 --> 00:20:47,680
different hues
of a grey-brown colour.

263
00:20:50,920 --> 00:20:53,800
This is his domain,

264
00:20:53,840 --> 00:20:55,880
and he's not one for sharing.

265
00:21:00,680 --> 00:21:04,240
She'll have no luck
on this stretch of beach.

266
00:21:06,360 --> 00:21:09,840
In this salty habitat,
snow rarely lingers.

267
00:21:11,920 --> 00:21:13,400
Her white coat,

268
00:21:13,440 --> 00:21:16,440
which camouflaged her
so well on the tundra,

269
00:21:16,480 --> 00:21:18,480
now works against her.

270
00:21:20,120 --> 00:21:22,200
(Pensive music)

271
00:21:25,640 --> 00:21:27,880
Whereas the blue morph's colouring,

272
00:21:27,920 --> 00:21:30,840
tailormade for this
ice-free environment,

273
00:21:30,880 --> 00:21:33,960
gives him a unique
evolutionary edge.

274
00:21:37,040 --> 00:21:40,440
And the numbers of his kind
are on the rise.

275
00:21:42,680 --> 00:21:48,240
As climate change increasingly
disrupts nature's calendar,

276
00:21:48,280 --> 00:21:52,120
white might no longer be
the most fitting colour here.

277
00:21:55,080 --> 00:21:59,960
By living near the sea,
where saltwater melts snow,

278
00:22:00,000 --> 00:22:03,520
the blue morph fox has
inadvertently prepared itself

279
00:22:03,560 --> 00:22:07,480
for a future where snowfall
could become more unpredictable.

280
00:22:13,280 --> 00:22:18,240
The transformative power of snow
is extraordinary.

281
00:22:18,280 --> 00:22:22,280
The collective force of trillions
of individual ice crystals,

282
00:22:22,320 --> 00:22:25,400
each one uniquely crafted.

283
00:22:28,880 --> 00:22:30,040
(Enchanting music)

284
00:22:30,080 --> 00:22:33,600
As water freezes,
the sorcery begins.

285
00:22:34,720 --> 00:22:37,040
Creating long icicles...

286
00:22:38,320 --> 00:22:40,040
..vast sheets...

287
00:22:41,480 --> 00:22:43,000
..huge blocks...

288
00:22:44,800 --> 00:22:48,320
and some of the most beautiful
and delicate patterns

289
00:22:48,360 --> 00:22:50,600
in the natural world.

290
00:22:50,640 --> 00:22:52,520
(Ice crackling)

291
00:22:53,600 --> 00:22:58,160
Snowflakes appear seemingly
out of thin air.

292
00:22:58,800 --> 00:23:03,600
Their fleeting, ephemeral nature
is what makes them so magical.

293
00:23:05,440 --> 00:23:09,160
Each ice crystal
is a one-of-a-kind phenomenon...

294
00:23:10,920 --> 00:23:13,760
..shaped by its origin story.

295
00:23:13,800 --> 00:23:15,720
(Clouds whooshing)

296
00:23:17,000 --> 00:23:21,520
It all begins high in the
atmosphere, within a cloud.

297
00:23:24,400 --> 00:23:27,720
When water vapour encounters
frigid temperatures,

298
00:23:27,760 --> 00:23:32,000
the individual droplets cling to
a microscopic dust particle

299
00:23:32,040 --> 00:23:34,120
found floating in the air...

300
00:23:36,720 --> 00:23:38,960
..and start to freeze.

301
00:23:39,000 --> 00:23:40,000
(Twinkling music)

302
00:23:41,640 --> 00:23:45,160
And as each dust particle
is shaped differently,

303
00:23:45,200 --> 00:23:48,640
so are the foundations
of every snowflake.

304
00:23:52,520 --> 00:23:56,920
More water molecules
then freeze around this core,

305
00:23:56,960 --> 00:24:01,240
creating the framework
for a tiny ice masterpiece.

306
00:24:04,360 --> 00:24:06,200
It extends outwards...

307
00:24:08,760 --> 00:24:12,240
..naturally forming
a six-armed lattice -

308
00:24:12,280 --> 00:24:15,120
the snowflake's signature shape.

309
00:24:16,680 --> 00:24:21,040
Each branch lengthens with every
minuscule addition of water.

310
00:24:23,640 --> 00:24:27,520
Its intricacies fashioned
by subtle variations.

311
00:24:30,280 --> 00:24:33,960
Dancing within its cloud,
it encounters pockets of air

312
00:24:34,000 --> 00:24:36,560
with different temperatures
and densities,

313
00:24:36,600 --> 00:24:39,440
which also influence the
snowflake's form and design.

314
00:24:41,600 --> 00:24:44,960
Some grow slender needles.

315
00:24:45,000 --> 00:24:47,920
Others bloom into
star-shaped crystals.

316
00:24:50,640 --> 00:24:53,280
By each taking a different journey,

317
00:24:53,320 --> 00:24:57,200
their identities are finessed
into something unique.

318
00:24:59,120 --> 00:25:02,760
It takes a billion billion
water molecules

319
00:25:02,800 --> 00:25:06,360
to make a single snowflake,

320
00:25:06,400 --> 00:25:11,720
sculpted in just fifteen minutes
of fleeting magic.

321
00:25:13,040 --> 00:25:14,640
(Enchanting music)

322
00:25:15,480 --> 00:25:18,160
As they continue to grow
bigger and heavier...

323
00:25:21,000 --> 00:25:22,800
..gravity eventually wins.

324
00:25:25,280 --> 00:25:28,200
Pulling them towards the Earth.

325
00:25:28,240 --> 00:25:32,520
Gracefully falling together,
their arms intertwine,

326
00:25:32,560 --> 00:25:34,840
forming fluffy clumps of snow.

327
00:25:36,680 --> 00:25:40,560
Snowflakes are one of nature's
true marvels.

328
00:25:40,600 --> 00:25:44,440
And when they settle,
blanketing the landscape,

329
00:25:44,480 --> 00:25:47,880
wildlife is forced
to find imaginative ways

330
00:25:47,920 --> 00:25:50,160
to escape the cold.

331
00:25:53,240 --> 00:25:54,880
(String music)

332
00:25:55,720 --> 00:25:58,800
Deep in the snow-covered
Japanese Alps...

333
00:26:03,240 --> 00:26:04,760
(Macaques chattering)

334
00:26:05,240 --> 00:26:10,080
..this troop of macaques scour
through the frozen drifts.

335
00:26:10,120 --> 00:26:11,920
(Macaques chattering)

336
00:26:13,000 --> 00:26:15,200
Food is scarce.

337
00:26:16,200 --> 00:26:17,680
(Twigs snapping)

338
00:26:22,320 --> 00:26:25,640
But their real prize
in this frosted world...

339
00:26:27,080 --> 00:26:28,640
..is warmth.

340
00:26:30,360 --> 00:26:32,080
(Water rippling)

341
00:26:34,920 --> 00:26:38,080
Geothermal forces
beneath the Earth's surface

342
00:26:38,120 --> 00:26:40,000
heat the groundwater here...

343
00:26:41,600 --> 00:26:44,720
..to a balmy 40 degrees Celsius.

344
00:26:46,280 --> 00:26:48,400
(Relaxing music)

345
00:26:53,520 --> 00:26:57,000
This troop is the only group
of monkeys in the world

346
00:26:57,040 --> 00:26:59,360
to enjoy a natural spa.

347
00:27:05,840 --> 00:27:10,240
A comforting bath where they
can escape the winter chill.

348
00:27:21,280 --> 00:27:26,280
But access to this exclusive
retreat is strictly controlled.

349
00:27:29,800 --> 00:27:34,600
The alpha male moves through
his subjects like a king.

350
00:27:36,240 --> 00:27:37,520
(Macaque chatters)

351
00:27:40,720 --> 00:27:45,560
Physical strength alone
secures his status.

352
00:27:45,600 --> 00:27:48,560
But his partner,
the alpha female,

353
00:27:48,600 --> 00:27:52,840
has earned her position by climbing
up through the social ranks.

354
00:27:56,280 --> 00:28:01,240
For most, the water is a welcome
escape and time to relax.

355
00:28:02,560 --> 00:28:04,160
But not for her.

356
00:28:05,640 --> 00:28:09,480
Her authority comes with a job

357
00:28:09,520 --> 00:28:11,720
as the enforcer of social rank.

358
00:28:14,240 --> 00:28:16,640
She holds court
in the warm water,

359
00:28:16,680 --> 00:28:20,960
attended by subordinates
who groom her, currying favour.

360
00:28:25,640 --> 00:28:29,120
At the pool's edge,
the outcasts wait.

361
00:28:32,560 --> 00:28:36,000
Watching, hoping for her
permission to bathe.

362
00:28:37,160 --> 00:28:39,800
Entrance is not a right.

363
00:28:39,840 --> 00:28:42,320
It's a privilege.

364
00:28:42,360 --> 00:28:45,120
Even when it's
minus 20 degrees outside,

365
00:28:45,160 --> 00:28:49,840
she decides who can benefit
from the soothing hot water

366
00:28:49,880 --> 00:28:52,320
and who can't.

367
00:28:52,360 --> 00:28:57,600
All based on strict hierarchy
and favouritism.

368
00:29:01,880 --> 00:29:04,280
One nod, and you're in.

369
00:29:04,320 --> 00:29:05,640
(Splashing)

370
00:29:12,520 --> 00:29:17,360
Nearby, her partner lounges,
unbothered by pool politics.

371
00:29:20,000 --> 00:29:23,400
Unlike him,
her power is precarious.

372
00:29:24,440 --> 00:29:26,840
(Tense music)

373
00:29:28,240 --> 00:29:33,680
Just one challenge to her rule,
and she could lose everything.

374
00:29:33,720 --> 00:29:35,080
(Macaques screeching)

375
00:29:42,080 --> 00:29:43,920
(Macaques continue screeching)

376
00:29:48,840 --> 00:29:52,520
So, despite the daily spa,

377
00:29:52,560 --> 00:29:56,960
for her, this is the most
stressful time of year.

378
00:29:57,000 --> 00:29:58,640
(Water rushing, gentle music)

379
00:29:59,440 --> 00:30:01,840
Order must be maintained

380
00:30:01,880 --> 00:30:05,080
if she's going to keep the perks
that come with the job.

381
00:30:08,120 --> 00:30:11,840
But in this frozen world,
it's worth it.

382
00:30:14,760 --> 00:30:16,600
While these monkeys
are fortunate enough

383
00:30:16,640 --> 00:30:19,160
to have the luxury
of a winter hot tub...

384
00:30:22,160 --> 00:30:25,280
..other creatures
need the force of a bulldozer

385
00:30:25,320 --> 00:30:27,560
to reach their own thermal waters.

386
00:30:32,520 --> 00:30:34,640
In the depths of winter,

387
00:30:34,680 --> 00:30:38,480
Yellowstone National Park
falls silent.

388
00:30:39,720 --> 00:30:41,680
(Gentle music)

389
00:30:41,720 --> 00:30:44,520
Each year,
over three metres of snow

390
00:30:44,560 --> 00:30:47,440
envelops this vast
volcanic landscape.

391
00:30:51,920 --> 00:30:55,960
Its sprawling forests
and plains transform,

392
00:30:56,000 --> 00:30:59,320
now locked in a deep freeze.

393
00:30:59,800 --> 00:31:03,600
For the wild residents,
life grinds to a halt.

394
00:31:03,640 --> 00:31:05,040
(Mountain goat bleating)

395
00:31:05,600 --> 00:31:07,160
Food vanishes.

396
00:31:09,000 --> 00:31:10,840
Trails disappear.

397
00:31:13,680 --> 00:31:16,080
Leaving many stranded.

398
00:31:19,680 --> 00:31:22,760
There's only one group
of municipal workers

399
00:31:22,800 --> 00:31:27,160
who can get this snowbound town
up and running again.

400
00:31:27,200 --> 00:31:28,920
(Country music)

401
00:31:30,000 --> 00:31:32,800
Bison are nature's snowploughs.

402
00:31:39,320 --> 00:31:42,240
This female is the
leader of the convoy.

403
00:31:44,040 --> 00:31:47,040
Her job? Creating roads in the snow.

404
00:31:50,440 --> 00:31:53,880
Broad and muscular,
driven by powerful neck muscles

405
00:31:53,920 --> 00:31:55,640
and extra long vertebrae,

406
00:31:55,680 --> 00:31:59,520
she ploughs through
even the deepest drifts.

407
00:32:00,920 --> 00:32:02,880
(Wind whistles, bison huffing)

408
00:32:07,560 --> 00:32:12,360
With every swing of her head,
she uncovers buried treasure,

409
00:32:12,400 --> 00:32:15,120
grasses locked beneath the snow.

410
00:32:23,080 --> 00:32:25,240
(Bison grunting)

411
00:32:27,360 --> 00:32:31,160
And as they clear the snow
to graze,

412
00:32:31,200 --> 00:32:34,880
their tracks become
Yellowstone's winter highways.

413
00:32:43,320 --> 00:32:45,040
Benefiting the community...

414
00:32:46,560 --> 00:32:49,640
..coyotes eagerly
follow the trail.

415
00:32:56,520 --> 00:33:00,280
And deer nibble vegetation
exposed by the bison.

416
00:33:02,440 --> 00:33:05,920
And smaller inhabitants
can roam again.

417
00:33:09,680 --> 00:33:11,920
The matriarch drives her way

418
00:33:11,960 --> 00:33:14,480
towards Yellowstone's
geothermal basins.

419
00:33:17,960 --> 00:33:19,960
(Bison grunting)

420
00:33:21,120 --> 00:33:25,600
Here, The Earth's heat
melts the snow,

421
00:33:25,640 --> 00:33:29,640
revealing expansive grasses
and mineral rich soils.

422
00:33:31,760 --> 00:33:33,600
(Enchanting music)

423
00:33:37,880 --> 00:33:40,000
Other bison herds gather,

424
00:33:40,040 --> 00:33:42,680
heading towards
the volcanic warmth.

425
00:33:47,760 --> 00:33:51,800
Together, they are the caretakers
of this wilderness.

426
00:33:54,320 --> 00:33:56,120
Along with snow clearing,

427
00:33:56,160 --> 00:33:59,320
their grazing and scattering
of nutrients

428
00:33:59,360 --> 00:34:02,240
leave behind
a healthier ecosystem.

429
00:34:03,680 --> 00:34:06,480
Come spring,
thanks to their work,

430
00:34:06,520 --> 00:34:10,960
bison grazed areas will regrow
faster and stronger.

431
00:34:12,960 --> 00:34:17,800
But there are other giants
made of ice

432
00:34:17,840 --> 00:34:20,159
that leave their stamp
on the landscape

433
00:34:20,199 --> 00:34:22,520
on a much grander scale.

434
00:34:26,560 --> 00:34:28,400
(Intriguing music)

435
00:34:29,800 --> 00:34:34,560
Glaciers have been weaving
their magic across our planet

436
00:34:34,600 --> 00:34:37,159
for billions of years.

437
00:34:37,199 --> 00:34:40,040
Shaping everything
in their path.

438
00:34:43,040 --> 00:34:46,080
These slow-moving rivers of ice

439
00:34:46,120 --> 00:34:50,880
flow to the rhythm
of a deeper passage of time,

440
00:34:50,920 --> 00:34:54,239
sculpting the land on their
relentless march onwards.

441
00:34:56,320 --> 00:34:59,240
They are the largest
moving objects on the planet

442
00:35:01,160 --> 00:35:05,400
and keepers of 70 percent
of Earth's fresh water.

443
00:35:08,000 --> 00:35:10,360
Gravity slowly propels them
downhill.

444
00:35:13,800 --> 00:35:17,360
Gouging out lakes and valleys
in their wake.

445
00:35:17,400 --> 00:35:19,480
(Awe-inspiring music)

446
00:35:20,600 --> 00:35:24,600
Their faces tell the story
of their long lives.

447
00:35:26,680 --> 00:35:30,760
A tapestry of dark deposits
reveals their journey

448
00:35:30,800 --> 00:35:34,440
through land and time.

449
00:35:34,480 --> 00:35:37,720
While their jagged spines
chronicle a lifetime

450
00:35:37,760 --> 00:35:40,040
of melting and refreezing.

451
00:35:43,640 --> 00:35:45,600
(Wind gusting)

452
00:35:47,360 --> 00:35:48,880
(Magical music)

453
00:35:51,240 --> 00:35:52,600
In contrast,

454
00:35:52,640 --> 00:35:56,840
their rarely seen underbelly
is as smooth as glass.

455
00:35:59,760 --> 00:36:03,000
Over eons,
the glacier's colossal weight

456
00:36:03,040 --> 00:36:08,880
has slowly compressed snow layers
into clear, solid ice.

457
00:36:12,960 --> 00:36:16,400
Allowing light to travel deeper
within its core.

458
00:36:16,440 --> 00:36:19,560
Producing a luminous
turquoise glow.

459
00:36:19,600 --> 00:36:21,480
(Water dripping and flowing)

460
00:36:23,520 --> 00:36:27,600
Some glaciers, like this one,
have a hollow heart.

461
00:36:32,800 --> 00:36:34,720
(Intriguing music)

462
00:36:35,480 --> 00:36:37,120
When temperatures warm...

463
00:36:39,480 --> 00:36:42,840
..the glacier's outer layers
start to melt.

464
00:36:46,440 --> 00:36:49,520
Droplets flow down
through tiny cracks.

465
00:36:52,200 --> 00:36:57,320
Forming streams of meltwater
that bleed from their midst,

466
00:36:57,360 --> 00:37:00,120
carving out
glimmering ice caves.

467
00:37:05,400 --> 00:37:09,280
Although glaciers have always
given way to seasonal fall,

468
00:37:09,320 --> 00:37:11,360
their melting is now accelerating

469
00:37:11,400 --> 00:37:14,160
at an alarming pace.

470
00:37:14,200 --> 00:37:15,800
(Ice and water roaring)

471
00:37:17,440 --> 00:37:19,400
As the world gets warmer,

472
00:37:19,440 --> 00:37:22,080
ancient waters
once frozen in time...

473
00:37:23,160 --> 00:37:24,760
(Ice crashing)

474
00:37:24,800 --> 00:37:27,040
..start to cascade

475
00:37:27,080 --> 00:37:30,720
from land, into sea.

476
00:37:32,640 --> 00:37:34,560
Causing sea levels to rise...

477
00:37:36,800 --> 00:37:38,280
..land to flood...

478
00:37:40,120 --> 00:37:42,320
..and storms to intensify.

479
00:37:43,000 --> 00:37:44,880
(Dramatic music)

480
00:37:46,640 --> 00:37:52,000
These towering giants are vital
to the health of our planet.

481
00:37:52,040 --> 00:37:54,680
Holding fresh water
locked in ice

482
00:37:54,720 --> 00:37:57,000
for hundreds
of thousands of years.

483
00:37:59,280 --> 00:38:01,920
While many still
stand firm today,

484
00:38:01,960 --> 00:38:04,920
their future remains uncertain.

485
00:38:09,320 --> 00:38:10,560
(Lively country music)

486
00:38:11,640 --> 00:38:16,280
Ice can bring even the mightiest
rivers to a standstill.

487
00:38:19,240 --> 00:38:23,840
Each winter, parts of
the Mississippi freeze over,

488
00:38:23,880 --> 00:38:27,840
trapping the unwary
beneath its glassy surface.

489
00:38:29,720 --> 00:38:34,080
But one creature's demise
becomes another's lifeline.

490
00:38:36,960 --> 00:38:41,120
As the shallow backwaters thaw,
opportunity arises.

491
00:38:42,640 --> 00:38:43,760
(Bird crying)

492
00:38:43,800 --> 00:38:45,960
And for one smart parent,

493
00:38:46,000 --> 00:38:48,880
it's the moment
they've been waiting for.

494
00:38:51,400 --> 00:38:53,160
(Wings fluttering)

495
00:38:53,200 --> 00:38:55,320
(Gentle music)

496
00:38:57,040 --> 00:39:01,920
While late winter may seem an
unlikely time to lay their eggs,

497
00:39:01,960 --> 00:39:06,360
these bald eagles know better.

498
00:39:06,400 --> 00:39:09,360
For this feisty
Midwestern mother of two,

499
00:39:09,400 --> 00:39:11,000
it makes perfect sense.

500
00:39:14,960 --> 00:39:19,240
She finds it easier to keep
her brood warm in the cold season

501
00:39:19,280 --> 00:39:22,840
than it is to keep them cool
in the heat of the summer.

502
00:39:25,520 --> 00:39:28,080
Plus, there's another big advantage.

503
00:39:29,040 --> 00:39:31,360
(Wind whistling)

504
00:39:32,080 --> 00:39:35,880
As the frozen river cracks
under the strengthening sun,

505
00:39:35,920 --> 00:39:38,600
it reveals the ultimate
winter bonus.

506
00:39:39,520 --> 00:39:42,400
A wealth of frozen fish.

507
00:39:42,440 --> 00:39:43,960
(Birds squawking)

508
00:39:44,000 --> 00:39:46,200
Starved of oxygen beneath the ice,

509
00:39:46,240 --> 00:39:48,600
they now float to the surface.

510
00:39:50,840 --> 00:39:52,600
Perfectly preserved.

511
00:39:54,080 --> 00:39:55,800
The only catch?

512
00:39:55,840 --> 00:39:57,680
Every other parent in
the neighbourhood

513
00:39:57,720 --> 00:39:59,840
has had the same idea.

514
00:40:00,960 --> 00:40:02,880
Time to get pushy.

515
00:40:03,360 --> 00:40:05,360
(Birds squawking)

516
00:40:07,720 --> 00:40:10,520
She can't afford
to go home empty handed.

517
00:40:19,200 --> 00:40:22,880
Her chicks demand
100 grams of food a day...

518
00:40:23,960 --> 00:40:25,480
..each.

519
00:40:28,800 --> 00:40:31,280
But as the ice continues to retreat,

520
00:40:31,320 --> 00:40:35,120
more victims of the freeze
rise to the surface...

521
00:40:38,960 --> 00:40:40,640
..ready for collection.

522
00:40:42,600 --> 00:40:44,360
(Joyful music)

523
00:40:50,000 --> 00:40:52,680
This fleeting moment of abundance,

524
00:40:52,720 --> 00:40:56,400
delivered by the freeze
and unlocked by the thaw,

525
00:40:56,440 --> 00:40:59,400
makes winter nesting a success,

526
00:40:59,440 --> 00:41:02,760
as it fuels her chicks'
incredible growth.

527
00:41:05,720 --> 00:41:09,440
In just two months,
they'll be strong enough to fledge,

528
00:41:09,480 --> 00:41:11,520
ready to take to the skies...

529
00:41:13,080 --> 00:41:14,400
Like their mum.

530
00:41:16,240 --> 00:41:19,280
In nature, timing is everything.

531
00:41:22,800 --> 00:41:25,760
Further north,
a creature's imminent journey

532
00:41:25,800 --> 00:41:29,920
could hold the power
to shape our planet's future.

533
00:41:35,080 --> 00:41:37,720
In the far reaches of Scandinavia,

534
00:41:37,760 --> 00:41:41,000
the approach of snow and ice
is about to kickstart

535
00:41:41,040 --> 00:41:44,560
a migration
on a truly immense scale.

536
00:41:45,800 --> 00:41:46,920
(Reindeer grunting)

537
00:41:48,640 --> 00:41:51,400
As the first flakes of snow arrive...

538
00:41:53,400 --> 00:41:56,200
..it serves as a signal
for these reindeer.

539
00:42:02,280 --> 00:42:06,160
Over the past summer months,
this three-thousand-strong herd,

540
00:42:06,200 --> 00:42:08,240
mostly mothers and calves,

541
00:42:08,280 --> 00:42:11,960
have gorged
on these coastal pastures.

542
00:42:12,000 --> 00:42:13,560
(Reindeer grunting)

543
00:42:15,360 --> 00:42:19,440
But now, their real challenge
is about to begin.

544
00:42:20,640 --> 00:42:22,160
For over ten thousand years,

545
00:42:22,200 --> 00:42:25,080
snow has dictated
their winter migration.

546
00:42:25,120 --> 00:42:27,040
(Uplifting music)

547
00:42:28,280 --> 00:42:30,400
The oldest and wisest of the herd

548
00:42:30,440 --> 00:42:32,840
will lead them across the landscape.

549
00:42:35,000 --> 00:42:36,960
(Reindeer grunting)

550
00:42:44,120 --> 00:42:48,920
And along the way, the influence
of water in all its forms

551
00:42:48,960 --> 00:42:51,640
continues to shape their destiny.

552
00:42:52,960 --> 00:42:54,760
(Suspenseful music)

553
00:42:56,440 --> 00:43:01,680
Norway's fjords, ice cold
and up to 1300 metres deep,

554
00:43:01,720 --> 00:43:04,280
hide a maelstrom of undercurrents.

555
00:43:04,320 --> 00:43:05,960
(Waves crashing)

556
00:43:07,640 --> 00:43:09,800
She has made
this crossing before.

557
00:43:13,160 --> 00:43:17,560
But for the calves, it's their
first experience of deep water.

558
00:43:20,000 --> 00:43:22,520
Reindeer are built for snow and ice.

559
00:43:23,920 --> 00:43:26,440
But frigid,
choppy water like this

560
00:43:26,480 --> 00:43:29,880
poses the most serious threat.

561
00:43:29,920 --> 00:43:33,320
Her instincts tell her to wait
for calmer conditions.

562
00:43:37,680 --> 00:43:39,440
(Reindeer grunting)

563
00:43:40,480 --> 00:43:42,160
When the weather breaks...

564
00:43:45,680 --> 00:43:48,680
she makes the pivotal decision

565
00:43:48,720 --> 00:43:51,800
and steps forward.

566
00:43:51,840 --> 00:43:55,400
The others cautiously
follow her lead.

567
00:43:58,040 --> 00:44:01,080
The fjord's strong currents
and near-freezing waters

568
00:44:01,120 --> 00:44:03,120
are still treacherous.

569
00:44:05,000 --> 00:44:08,880
But reindeer are strong swimmers.

570
00:44:08,920 --> 00:44:13,280
Their powerful athletic legs
and wide concave hooves

571
00:44:13,320 --> 00:44:15,520
propel them through the water.

572
00:44:15,560 --> 00:44:17,680
(Tense music)

573
00:44:18,880 --> 00:44:20,960
But the crossing is long.

574
00:44:22,720 --> 00:44:24,320
As fatigue kicks in...

575
00:44:26,400 --> 00:44:29,040
..the calves struggle,

576
00:44:29,080 --> 00:44:31,680
their small bodies fighting
the currents...

577
00:44:37,640 --> 00:44:39,320
..and the cold.

578
00:44:40,720 --> 00:44:42,520
(Perilous music)

579
00:44:45,840 --> 00:44:49,920
The weary herd just need
one last push...

580
00:44:52,120 --> 00:44:53,920
..to reach the shore.

581
00:45:01,120 --> 00:45:02,920
(Reindeer grunting)

582
00:45:06,200 --> 00:45:10,080
This year, every member
has survived the crossing.

583
00:45:13,760 --> 00:45:17,240
Only another 80 kilometres to go.

584
00:45:17,280 --> 00:45:18,880
(Wind gusting)

585
00:45:18,920 --> 00:45:20,720
(Gentle music)

586
00:45:31,920 --> 00:45:36,720
Finally, they arrive at the
high plateaus, their winter home.

587
00:45:38,680 --> 00:45:40,440
(Enchanting music)

588
00:45:40,480 --> 00:45:44,160
Here, they can feast on
the carbohydrate rich lichen

589
00:45:44,200 --> 00:45:46,120
hidden just under the snow.

590
00:45:53,240 --> 00:45:55,680
It's the seasonal rhythm
of the Arctic ice

591
00:45:55,720 --> 00:45:58,480
that guides the reindeer
to these highlands.

592
00:46:01,640 --> 00:46:05,400
As they travel across
the vast landscape,

593
00:46:05,440 --> 00:46:09,080
their appetite plays a crucial
role in maintaining the balance

594
00:46:09,120 --> 00:46:11,800
of not just their ecosystem...

595
00:46:13,200 --> 00:46:16,280
..but the entire planet too.

596
00:46:18,680 --> 00:46:21,560
Throughout the year,
as reindeer graze,

597
00:46:21,600 --> 00:46:24,880
they trim back grasses
and shrubs,

598
00:46:24,920 --> 00:46:28,040
preventing them
from taking over the tundra.

599
00:46:28,080 --> 00:46:32,280
Allowing snow to settle unbroken

600
00:46:32,320 --> 00:46:35,520
in a shroud of pure white.

601
00:46:37,320 --> 00:46:39,680
Rather than absorbing
the sun's rays,

602
00:46:39,720 --> 00:46:43,160
this snow blanket
acts like a giant mirror,

603
00:46:43,200 --> 00:46:46,600
reflecting the solar heat
back into space.

604
00:46:48,520 --> 00:46:50,600
Known as the Albedo effect,

605
00:46:50,640 --> 00:46:54,360
this simple act keeps
the Arctic cold,

606
00:46:54,400 --> 00:46:59,160
which in turn creates more snow,
to deflect more heat.

607
00:47:03,800 --> 00:47:05,960
And when these cooler
temperatures are mixed

608
00:47:06,000 --> 00:47:07,720
with the warmth of the tropics,

609
00:47:07,760 --> 00:47:11,320
it helps stabilise
our global temperature.

610
00:47:11,880 --> 00:47:13,520
(Pensive music)

611
00:47:14,840 --> 00:47:18,320
It's vital that the poles
retain their snow cover

612
00:47:18,360 --> 00:47:20,640
for as long as possible each winter.

613
00:47:22,520 --> 00:47:24,920
And driven by the ice itself,

614
00:47:24,960 --> 00:47:27,720
these reindeer
are playing their part.

615
00:47:28,440 --> 00:47:29,960
(Majestic music)

616
00:47:30,000 --> 00:47:34,600
Every step they take echoes
far beyond their frozen realm

617
00:47:34,640 --> 00:47:39,080
to safeguard
this blue planet we all share.

618
00:47:40,640 --> 00:47:42,600
(Enchanting, majestic music)

619
00:47:43,800 --> 00:47:45,720
Water...

620
00:47:45,760 --> 00:47:47,760
from ice...

621
00:47:47,800 --> 00:47:50,400
to ocean...

622
00:47:50,440 --> 00:47:54,720
is our most dynamic force of nature.

623
00:47:54,760 --> 00:47:59,360
Life on Earth simply
wouldn't exist without it.

624
00:48:00,560 --> 00:48:03,640
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