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The story of life on Earth

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has been marked

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by a series of catastrophic
extinction events.

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Natural disasters which have
threatened to wipe out

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many of the creatures
that call our planet home.

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But after every brush
with death

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life has come back
even stronger.

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One of the most recent disasters

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happened just
12,000 years ago

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in North America.

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A vast dam of ice
and rock collapsed,

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unleashing one of
the greatest floods

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the world has ever seen.

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A catastrophe so enormous,

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it slammed the Northern
Hemisphere back into an ice age.

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In this turmoil,

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even the mightiest
struggled to survive.

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But out of the chaos

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rose the most dominant species
on Earth today

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Humans.

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Northern North America

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at the end
of the last Ice age.

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A land of glaciers,
snow, and ice.

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While the frozen landscapes

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and endless forests
may look familiar

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the giant creatures that
live amongst them

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are anything but.

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A dire wolf.

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A whole one third bigger than
the gray wolf we know today.

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He’s picked up the scent
of fresh blood.

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His nose leads him
to an abandoned carcass.

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Something to fill his belly.

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A giant short-faced bear...

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...North America’s
largest bear ever.

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She is ferocious,

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especially now she’s defending
two new cubs.

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This Mama Bear needs
all the meat she can get

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to help them all survive
their long hibernation.

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Three months later,

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spring arrives
across North America.

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It’s coming earlier
with each passing year.

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The Ice Age that has gripped
the Earth

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for tens of thousands of years
is losing its hold.

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As the snow and ice melt away,

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the wonderful creatures of
these dense forests

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begin to stir.

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The lush new growth has drawn
in other animals...

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...like these mammoths.

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Outside her den,

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Mama Bear prepares for
her first hunt of the spring.

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Her cubs want to tag along,

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but they are still too small
to leave the den.

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Before she hunts,

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she needs to do something

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she’s been
dreaming of all winter.

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Oh yeah, that’s the spot.

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Yet, this is much more
than back-scratching.

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She’s marking her territory
by spreading her unique scent,

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vital for warning
off other bears

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while her cubs are home alone.

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And now, onto the hunt.

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She picks up
the distinctive smell of prey.

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After months of hibernation,

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she’s lost a third
of her body weight

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and is ravenous.

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A shelter, which can mean
only one thing...

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humans.

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Only a handful
of humans roam these lands.

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And they’re smart enough not
to mess with a giant bear.

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This Mama Bear
is still too heavy

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to climb a tree,
even though she’s half starved.

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Our giant short-faced bear,
however,

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is dwarfed by
a much greater force.

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One that looms
over her territory.

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Only a few miles from her den,
the Laurentide Ice Sheet.

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Formed during an ice age that
gripped the Earth

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for tens of
thousands of years,

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it covers millions of
square miles

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of the North American continent,

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north of the Great Lakes.

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It is one of the largest
expanses of ice

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the world has seen in hundreds
of millions of years.

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But now,
as temperatures rise,

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this massive ice sheet
is melting.

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Downstream, the meltwater
is swelling rivers.

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A stag-moose.

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Our Mama Bear knows
there’ll be easier prey.

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A stag-moose is a formidable
foe With six-foot antlers.

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But this one is old
and past his prime.

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And he is unaware
he’s being tracked

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A dire wolf.

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Still, no threat
to this old boy.

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Except this wolf
brought friends.

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After a desperate winter,
they have formed a super pack.

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Now, even the giant moose
is in trouble.

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It is the end of the last
Ice Age 12,000 years ago

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and still, most of
what will become Canada

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is covered in
an ancient ice sheet.

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However, this is
beginning to melt,

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swelling all the local rivers.

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In a valley below,

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our older stag-moose has been
targeted by dire wolves.

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They have formed a super pack

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and now, even powerful animals
like this stag-moose are prey.

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Few animals can outrun a pack
of dire wolves for long.

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Our stag-moose chooses deep
waters, over being eaten alive.

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But this river is now swollen
by water from the melting ice.

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And the current
is too strong to fight.

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It was a brave attempt.

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The wolves watch

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to see if
the stag’s body washes up

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at the bottom of the falls.

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Eventually, they give up.

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Miracles can happen

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and this old timer is proof.

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He has survived the falls.

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He’s lost an antler,

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but it’s a small price to pay
for cheating death.

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Months later,
spring gives way to summer.

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Our Mama Bear is now well-fed

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and is taking her cubs
on field trips

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further and further
from their den.

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In the valley,
there are more mammoths now

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And they’ve been joined
by a distant cousin...

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a mastodon.

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Shorter than a modern elephant,
but more heavily built.

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Mammoth and mastodon have
roamed this continent together

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for millions of years.

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Yet all these creatures
are living on borrowed time.

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The giant ice sheet
is a ticking time bomb.

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As it continues to melt,

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it’s doing more
than just swelling rivers.

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Vast quantities of water
are on the move.

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Trickles feed streams
that turn into torrents.

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Entire rivers vanish down
deep holes in the ice.

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But this glacial meltwater
doesn’t just disappear.

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Along the edge of
the Laurentide Ice Sheet,

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a giant lake
has been building...

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year by year.

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Now, it covers an area

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larger than all
the Great Lakes combined.

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23 hundred cubic miles
of meltwater,

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held back by dams
of rock and ice.

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And as the pressure builds,

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these dams are about to break.

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The magnificent creatures in
the valleys

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have no idea what’s on its way.

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The vast Laurentide Ice Sheet
that covers most of Canada

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is melting and along its edges,
enormous lakes have developed.

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So far, they have been
held back by ice dams,

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but they are about to reach
their breaking point.

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On the wooded slopes below,

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our Mama Bear has poached
a fresh carcass.

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But her cubs are not
where she left them.

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A mother’s work is never done.

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They are playing hooky,

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lured away by a fascinating,
prickly creature...

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a porcupine.

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With 30,000 barbed quills
covering his body,

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most in this forest
just leave him alone.

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Our naive cubs, however,
are new to the neighborhood.

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Rude.

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Our Mama Bear’s jaws may be
bone-crushingly powerful,

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but she can also use them
for delicate cub maintenance.

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This little one won’t be
messing with porcupines again.

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After months of
only their mother’s milk,

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this is the cubs’
first taste of meat.

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But Mama Bear senses
something’s not right.

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She leads her cubs back up
toward their den,

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high on the hillside.

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The giant wall of ice
finally breaks.

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Thousands of cubic miles
of glacial meltwater

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tear across North America
toward the Atlantic Ocean.

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This event, 12,000 years ago,

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is one of the greatest
flash floods

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in the history of the planet.

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Two months after
the catastrophic flood,

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a landscape decimated
by water and ice.

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Desolate, lifeless, except...

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our bears have survived.

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Mama bear’s instinct
saved her babies

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by heading up to the den.

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At this time of year,
they should be feasting.

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Instead, they are all starving.

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Another creature
that has survived the flood.

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A huge male short faced bear;

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but he’s not interested
in mating.

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He’s hunting the cubs.

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There is no chance to run.

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Our giant Mama Bear
has met her match.

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A gigantic flood
containing thousands

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of cubic miles of meltwater

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has stripped
this landscape bare.

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And now the few animals left

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face a bleak
struggle for survival.

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For our mama bear and her cubs,

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their worst nightmare
has just tracked them down.

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A hungry male.

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He is larger.

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But this mom
will fight to the death

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to defend her young.

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The winner of this battle
will decide the cub’s fate.

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A truce... for now.

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The male bear
has the cub’s scent.

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This is not over.

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Days later, tragedy.

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Our mama bear
did eventually lose

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one of her cubs to the male.

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Her whole world has been turned
upside down since the flood.

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But the devastation
is far wider.

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The deluge has swept
across the Great Lakes

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and followed
the St. Lawrence river,

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leaving a path
of destruction 500 miles long.

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And dumping 2,300 cubic miles

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of cold freshwater
into the Atlantic.

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The massive
outpouring of water

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changed the movement
of the ocean...

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leading to the collapse
of the North Atlantic current.

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Usually it transports as much
warm water northwards

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as 100 Amazon rivers.

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Now this vast source
of thermal energy

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has been interrupted
by the megaflood

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sending the northern hemisphere
back into the ice age.

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Most animals here
are tough and resilient

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and have seen cold
periods come and go.

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Large animals like mammoths
are able to move away

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in a desperate search
for something to eat.

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But these bears don’t migrate.

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00:27:07,250 --> 00:27:11,129
Our heartbroken mama bear
has found a new den

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to escape being discovered
by the male bear.

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In this cold weather,
they should start to hibernate.

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But she doesn’t
have enough milk

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to sustain her cub
to another winter.

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She must find more food.

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She’s alone
in this frozen wilderness.

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00:28:26,621 --> 00:28:29,082
She smells something familiar.

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Humans.

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Several families
drawn together.

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In these extreme conditions,

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they stand a better
chance of survival as a group.

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And it’s paid off, hunting
caribou.

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They even have enough to share.

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It’s dangerous approaching
this many humans.

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She is desperate, but this
is a fight she could lose.

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Following
the collapse of ocean currents,

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Ice Age rules
have returned to North America.

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00:29:40,194 --> 00:29:43,281
The speed of this climate change
has been catastrophic

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for some of the animals here.

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00:29:48,536 --> 00:29:52,123
Our Mama Bear has been unable
to prepare for hibernation

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00:29:52,164 --> 00:29:55,669
and now has
to leave her cave and her cub

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00:29:55,710 --> 00:29:58,046
in a desperate search for food.

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00:29:59,463 --> 00:30:02,842
Her nose leads her
to a human encampment

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but stealing from humans
carries enormous danger.

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She is huge but they are many,
and equally desperate.

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00:30:43,633 --> 00:30:45,593
She makes her escape

256
00:31:00,942 --> 00:31:05,280
She retreats after scavenging
some of the humans’ caribou.

257
00:31:08,699 --> 00:31:10,160
It’s not much,

258
00:31:10,201 --> 00:31:12,704
but it should
sustain her cub for now.

259
00:31:19,543 --> 00:31:22,755
The price, however,
has been high.

260
00:31:25,383 --> 00:31:28,803
There is a spear
deep in her side.

261
00:31:30,596 --> 00:31:37,312
She risked it all for her cub,
but soon he will be all alone.

262
00:31:40,314 --> 00:31:44,527
The Mama Bear’s strength
and devotion was enormous

263
00:31:45,194 --> 00:31:48,323
but it was no match
for this climate shock.

264
00:31:55,579 --> 00:31:58,375
The disruption
of the North Atlantic Current

265
00:31:58,416 --> 00:32:00,877
and rapid
cooling in North America

266
00:32:00,918 --> 00:32:03,254
has far reaching implications.

267
00:32:04,672 --> 00:32:08,843
For 1,000 years, ice age
conditions return,

268
00:32:08,884 --> 00:32:10,595
with fleeting summers,

269
00:32:10,636 --> 00:32:15,016
and winters that are much
longer, and colder.

270
00:32:15,558 --> 00:32:19,604
For all the creatures here,
it’s a profound climate shock.

271
00:32:21,272 --> 00:32:23,483
But, in an ever changing world,

272
00:32:23,524 --> 00:32:27,612
eventually, the warm
Atlantic currents recover.

273
00:32:28,404 --> 00:32:30,323
And temperatures shoot back up,

274
00:32:30,364 --> 00:32:32,784
even more quickly
than they dropped.

275
00:32:33,868 --> 00:32:36,621
At one point,
average temperatures rise

276
00:32:36,662 --> 00:32:40,166
by 18 degrees
in just a few decades.

277
00:32:41,709 --> 00:32:44,421
The impact
of violent swings in climate

278
00:32:44,462 --> 00:32:47,090
are too much
for many larger animals...

279
00:32:47,298 --> 00:32:50,468
...like
the giant short-faced bears.

280
00:32:51,302 --> 00:32:53,513
And yet, it is the making

281
00:32:53,554 --> 00:32:56,599
of one particular
mammal species...

282
00:32:57,016 --> 00:32:59,310
...humans.

283
00:33:09,236 --> 00:33:12,156
Life has rebounded...

284
00:33:13,324 --> 00:33:15,076
... but is still racing
to catch up

285
00:33:15,117 --> 00:33:17,328
with the increasing
temperatures.

286
00:33:20,873 --> 00:33:23,501
Some familiar
creatures are thriving...

287
00:33:24,877 --> 00:33:31,342
... including elk,
caribou and musk ox.

288
00:33:34,345 --> 00:33:37,682
But few
of the ice age giants remain.

289
00:33:39,725 --> 00:33:42,604
There were once tens
of thousands of mastodons

290
00:33:42,645 --> 00:33:44,564
in this part of North America.

291
00:33:46,315 --> 00:33:50,862
Now this tired old male
is the last of his kind...

292
00:33:52,488 --> 00:33:55,116
forever in search of a mate.

293
00:33:59,703 --> 00:34:02,874
Today, at least,
he has found some company.

294
00:34:04,291 --> 00:34:07,712
A mother mammoth
with her seven-year-old calf.

295
00:34:08,921 --> 00:34:10,757
The iconic species

296
00:34:10,798 --> 00:34:13,384
is also teetering
on the edge of extinction.

297
00:34:18,097 --> 00:34:20,391
But these majestic creatures

298
00:34:20,683 --> 00:34:23,436
face a more
immediate challenge...

299
00:34:30,025 --> 00:34:31,861
Hunters.

300
00:34:47,126 --> 00:34:51,589
Once, these powerful animals
had little to fear from people.

301
00:34:53,382 --> 00:34:55,927
Now, things have changed.

302
00:34:58,512 --> 00:35:00,974
While the mastodon may be old,

303
00:35:01,015 --> 00:35:03,851
he can still leave
the humans in the dust.

304
00:35:04,977 --> 00:35:08,564
But these hunters
aren’t trying to catching up...

305
00:35:08,939 --> 00:35:12,735
...they are herding them
straight into a trap.

306
00:35:26,123 --> 00:35:29,418
A thousand years
after the Great Flood...

307
00:35:30,502 --> 00:35:33,047
The imperious
giants of the ice age,

308
00:35:33,088 --> 00:35:34,966
like mastodon and mammoths,

309
00:35:35,007 --> 00:35:38,052
once had little
to fear from humans.

310
00:35:39,720 --> 00:35:42,724
Now, humans
have grouped together

311
00:35:42,765 --> 00:35:45,518
to become ruthless hunters.

312
00:35:46,518 --> 00:35:49,522
They have become
the apex predator.

313
00:35:52,566 --> 00:35:55,153
These giants
are being driven exactly

314
00:35:55,194 --> 00:35:57,446
to where the humans want them.

315
00:36:00,574 --> 00:36:02,994
The hunters have spears.

316
00:36:03,744 --> 00:36:07,624
These are heavy, and tipped
with razor-sharp flint,

317
00:36:07,665 --> 00:36:11,002
capable
of piercing thick hide.

318
00:36:38,237 --> 00:36:40,782
The spear
has pierced a vital organ

319
00:36:40,823 --> 00:36:43,034
of this poor mother mammoth.

320
00:37:06,348 --> 00:37:10,144
By nightfall,
it’s all over.

321
00:37:13,897 --> 00:37:17,485
The old mastodon
has survived yet again.

322
00:37:17,943 --> 00:37:21,781
But he will remain
a tempting target for humans...

323
00:37:22,114 --> 00:37:25,451
... and will be lucky
to make it through the fall.

324
00:37:39,465 --> 00:37:44,595
For the humans, the killing
of a mammoth is a rare feat.

325
00:37:46,430 --> 00:37:49,183
So there is good
reason to celebrate.

326
00:37:55,189 --> 00:37:59,819
There are still only about
10,000 humans in North America,

327
00:38:02,029 --> 00:38:04,532
but they are skilled
hunters...

328
00:38:05,949 --> 00:38:10,997
...and, as a group, are able
to kill any animal they choose.

329
00:38:13,999 --> 00:38:19,005
This is what finishes off
the last of the Ice Age giants.

330
00:38:20,089 --> 00:38:23,884
It is the price
of human success.

331
00:38:33,685 --> 00:38:35,813
12,000 years have passed...

332
00:38:35,854 --> 00:38:38,399
since the great American flood

333
00:38:38,440 --> 00:38:41,694
led to the collapse
of the North Atlantic Current.

334
00:38:42,861 --> 00:38:47,033
Today, there are signs
it may happen again.

335
00:38:48,117 --> 00:38:50,536
Our warming planet
is now melting

336
00:38:50,577 --> 00:38:52,997
the Greenland Ice sheet
in the Arctic ...

337
00:38:53,038 --> 00:38:56,000
and vast amounts
of icy freshwater

338
00:38:56,041 --> 00:38:59,670
are pouring into
the North Atlantic every year.

339
00:39:01,630 --> 00:39:04,384
We now know
from the great ice age flood,

340
00:39:04,425 --> 00:39:08,220
the profound impact
on climate this could have.

341
00:39:12,933 --> 00:39:15,019
Extinction events
from Earth’s past

342
00:39:15,060 --> 00:39:18,689
can teach us a great deal
about our future...

343
00:39:22,901 --> 00:39:25,405
... Whether it’s toxic oceans...

344
00:39:25,446 --> 00:39:28,366
...rising carbon dioxide...

345
00:39:28,407 --> 00:39:31,243
...or falling asteroids...

346
00:39:33,078 --> 00:39:36,749
...our beautiful planet
can become a harsh home.

347
00:39:41,962 --> 00:39:46,259
But as we’ve seen,
life always adapts...

348
00:39:46,300 --> 00:39:49,178
and comes back stronger.

349
00:40:17,664 --> 00:40:21,878
Now, once again,
the Earth is changing.

350
00:40:21,919 --> 00:40:25,923
Unlike the catastrophes
of the past, however...

351
00:40:25,964 --> 00:40:28,968
there is one important
difference:

352
00:40:30,677 --> 00:40:34,432
This time,
one species has control

353
00:40:34,473 --> 00:40:36,892
over the causes of the change.

354
00:40:39,853 --> 00:40:42,523
♪ Trees of green ♪

355
00:40:42,564 --> 00:40:45,359
♪ Red roses, too ♪

356
00:40:45,400 --> 00:40:51,491
♪ I watched them bloom
for me and you ♪

357
00:40:51,532 --> 00:40:54,785
♪ And I think to myself ♪

358
00:40:55,869 --> 00:41:02,627
♪ What a wonderful world ♪

359
00:41:02,668 --> 00:41:07,047
♪ Yes,
I think to myself ♪

360
00:41:08,507 --> 00:41:12,970
♪ What a wonderful world ♪