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♪ ♪

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NARRATOR:
252 million years ago,

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a catastrophe killed
nearly all life on Earth.

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This is closest our planet
has ever been

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to going back to square one.

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As many as 90% of species
across the Earth died.

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SURESH SINGH:
This extinction was much greater

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than the one that ended
the age of the dinosaurs.

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NARRATOR:
But an asteroid wasn't to blame.

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SONIA TIKOO:
It is not easy to kill
so many species,

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so this had to be something
utterly catastrophic.

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(rumbling)

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NARRATOR:
The culprit was lurking

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just beneath the surface.

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We're finally able to
piece together

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clues from this
ancient crime scene.

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Now we finally know
the culprit:

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enormous volcanic eruptions.

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TIKOO:
It is as if the Earth itself
turned on life.

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NARRATOR:
Yet some life stubbornly
hung on.

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♪ ♪

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And when the threat passed,

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thrived again.

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PAUL WIGNALL:
Mass extinction events,

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although terrible, provide new
opportunities for life.

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Death and extinction

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shaped the biodiversity
of the living world.

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♪ ♪

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NARRATOR:
From the ashes of a lost world

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comes the story of

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"Ancient Earth: Inferno."

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Right now, on "NOVA."

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♪ ♪

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♪ ♪

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NARRATOR:
In a time long before

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the rise of
human civilization...

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♪ ♪

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Before the last
glacial period...

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♪ ♪

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Before an asteroid impact
wiped out the dinosaurs...

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♪ ♪

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In fact, a time before dinosaurs
even existed at all...

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An apocalypse destroyed
nearly all life on Earth,

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and it may hold lessons
for our future.

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♪ ♪

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Over a quarter of a billion
years ago,

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the disaster looms.

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♪ ♪

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("Never Close Enough"
by SIPHO. playing)

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♪ Oh, we won't ever hear
the silence ♪

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♪ Or ever see the colors ♪

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(exploding)

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♪ That never lived in
our minds ♪

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♪ ♪

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♪ Just a moment ♪

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♪ Never too far out ♪

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♪ Never close enough ♪

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♪ ♪

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NARRATOR:
253 million years ago.

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Earth looks very
different than it does today.

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On one side, a water world.

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No land in sight.

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♪ ♪

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But on the other side,

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Earth's landmasses are clustered

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into a colossal supercontinent.

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♪ ♪

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This is Pangaea.

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♪ ♪

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Lush forest ecosystems flourish.

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(animals grunting)

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♪ ♪

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And its waters teem with

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weird and wonderful creatures.

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♪ ♪

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The Permian Earth is
rich, diverse,

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and full of life.

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♪ ♪

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There are no ecosystems
on Earth today

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that look exactly like those of
the Permian period,

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but some share
a few similarities.

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♪ ♪

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Life at the end of the Permian
was beautiful.

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We had a very diverse ecosystem,

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both in the marine realm, but
also on land.

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EMMA DUNNE:
It doesn't contain any mammals,

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any birds, any flowers,

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so completely different.

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♪ ♪

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JEFFREY BENCA:
But you would recognize

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some of the early forerunners

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to our modern conifers,
for example.

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♪ ♪

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So, the rock I'm holding here

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has a lot of fossil leaves

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from a plant called
Glossopteris--

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one of the tree-forming plants

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that lived in
the Southern Hemisphere.

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It's pretty cool to hold a
fossil from that time period.

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It's like going back

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in a, in a time machine.

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♪ ♪

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NARRATOR:
Pangaea is dominated by
animals that lived before

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dinosaurs and mammals evolved.

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(animals grunting)

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Forgotten creatures that
scientists only know about

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from the fossil record.

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You would have had

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these giant armored herbivores

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with these crazy, big, bony
sort of processes

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on their skulls called
pareiasaurs.

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BRANDON PEECOOK:
And the big predators are
called gorgonopsians.

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They've got a mouth full of
sharp teeth.

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Smaller sharp teeth up in the
front,

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and then
these incredible sabers.

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This is the first time
that we know of predators

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evolving saber teeth
to kill their prey.

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On land during the Permian,
we had insects, as well.

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We see wings,
some of which span

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more than a foot long.

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Much larger than
the ones we see today.

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♪ ♪

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DUNNE:
And we also see the very first
beetles.

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The beetles haven't appeared yet
in the fossil record

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until about the Permian.

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NARRATOR:
There is also great diversity
to be found in the oceans.

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The oceans would look

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completely different to now,

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but with a couple of familiar
characters,

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ray-finned fish and sharks.

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There were lots of reefs,

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but made of very different
types of organisms.

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And there would have been
trilobites

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scuttling about on the ocean
floor--

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more or less seafloor bugs.

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By the end of the Permian, life
had become

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very rich and diverse in, in a
whole range

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of habitats,
both on land and in the sea.

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SINGH:
I would love to go back

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and see all these animals
living together.

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It would be
a great prehistoric safari.

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♪ ♪

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NARRATOR:
But life is about to change
forever.

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Deep beneath Northern Pangaea,

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superheated liquid rock--
magma-- is rising.

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It pushes up against

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the Earth's rigid upper layer,
the crust,

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until it can take no more.

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♪ ♪

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The crust splits open.

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(erupting)

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Within hours,

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the local landscape
is torn apart.

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Cracks grow,
forming great curtains of fire,

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as lava floods onto the surface.

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♪ ♪

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The insides of Earth spew out.

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The eruptions came from
a giant volcanic system

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in Northern Pangaea
called the Siberian Traps.

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♪ ♪

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The remnants, the rock record

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of these volcanic eruptions,

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still exists in Siberia.

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♪ ♪

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There's a huge footprint of lava
left behind,

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covering a huge area
of modern-day Siberia.

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BURGESS:
I've actually been to
the Siberian Traps

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and floated down rivers
where both sides of the river

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were huge cliffs of
stacked-up lava flows.

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♪ ♪

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NARRATOR:
These rocks reveal that
the Siberian Traps

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erupted on and off
for around two million years...

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♪ ♪

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...emitting about 700,000
cubic miles of magma and rock.

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The eruptions at the end of
the Permian are absolutely huge.

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They're, they're vastly greater
in scale

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than anything
that we've seen today.

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WHITESIDE:
This is a planetary-scale
eruption that would

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cover the United States
in lava around 300 yards deep.

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♪ ♪

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NARRATOR:
We can try to grasp the scale
of these eruptions

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by comparing them
to recently active volcanoes.

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Witnessing a volcanic eruption

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just gives you a sense of how
powerful

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the Earth is.

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MATHER:
The explosions make
the ground throb,

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so you can feel sound traveling
through your whole body.

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♪ ♪

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And the smell and the fumes
can be really intense.

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♪ ♪

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NARRATOR:
In 2021,

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the volcano Tajogaite erupted
and released around

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300 million cubic yards
of material.

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That's enough to fill...
80 football stadiums?

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NARRATOR:
Other eruptions in
human history,

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like the Krakatau Volcano,
were much bigger.

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MATHER:
So, when Krakatau erupted
in the 1880s,

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it spewed out about
two cubic miles of magma.

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YING CUI:
The eruption was so large

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that it led to global
temperature decrease

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because of the gases emitted.

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NARRATOR:
But even Krakatau was minuscule
compared to the eruptions...

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(eruption roars)

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00:11:26,533 --> 00:11:29,000
...of the Siberian Traps.

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♪ ♪

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WHITESIDE:
The Siberian Traps would be like
a Krakatau erupting

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every year for 300,000 years.

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NARRATOR:
Eruptions on this vast scale

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are devastating to life nearby.

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♪ ♪

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Fire fountains blast
volcanic material

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00:11:54,266 --> 00:11:58,566
up into the atmosphere.

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00:11:58,566 --> 00:12:02,866
Untold numbers of creatures
perish in the forest fires

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00:12:02,866 --> 00:12:06,033
that burn close by.

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00:12:06,033 --> 00:12:11,333
Sulfur dioxide builds up and
reacts in the atmosphere,

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partially blocking out the sun.

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Plants wilt and die as
a volcanic winter sets in.

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♪ ♪

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Ash falls on a dying landscape.

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After each eruption,

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vast swaths of Northern Pangaea
are scorched.

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00:12:38,166 --> 00:12:42,666
But is it enough to
cause mass extinction?

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00:12:42,666 --> 00:12:46,933
♪ ♪

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Although these
early eruptions are huge,

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Pangaea is big, too.

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Most of the supercontinent

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remains untouched by
deadly lava.

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Elsewhere in Pangaea,
something curious is happening.

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♪ ♪

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A strange haze hangs in the air.

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00:13:21,033 --> 00:13:23,566
♪ ♪

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00:13:23,566 --> 00:13:29,333
Created by nutrient-rich
volcanic ash and sulfur,

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blown here from the eruptions

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happening
thousands of miles away.

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00:13:36,566 --> 00:13:38,966
♪ ♪

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At first, plant life seems
unaffected,

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and may have even benefited
from the nutrients and the ash.

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There is no mass extinction.

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For now.

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But death is coming.

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00:14:03,333 --> 00:14:08,700
♪ ♪

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These rocks,
formed 252 million years ago,

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contain evidence
of a massive die-off.

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00:14:21,666 --> 00:14:24,166
As we go up
in this section,

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00:14:24,166 --> 00:14:27,300
we are traveling
forward in time.

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00:14:27,300 --> 00:14:32,433
So, these rocks here are older
than the ones on the top.

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00:14:32,433 --> 00:14:35,400
♪ ♪

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00:14:35,400 --> 00:14:39,400
NARRATOR:
These ancient rocks were
formed on the ocean floor,

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00:14:39,400 --> 00:14:42,800
before being pushed up
to make these mountains.

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Rocks not only tell us about

251
00:14:48,100 --> 00:14:50,233
the environment in which
they were formed,

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00:14:50,233 --> 00:14:52,666
but something
extraordinary about them,

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00:14:52,666 --> 00:14:54,633
it's that they are
full of fossils.

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00:14:54,633 --> 00:14:59,366
So, for example, clams,
marine snails,

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00:14:59,366 --> 00:15:03,533
shelled organisms,
and other fossils,

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00:15:03,533 --> 00:15:05,266
like this nautilus,

257
00:15:05,266 --> 00:15:07,666
that were living during
that time.

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NARRATOR: The diverse fossils in
these rocks show that this

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00:15:12,366 --> 00:15:15,966
was a vibrant marine ecosystem.

260
00:15:15,966 --> 00:15:20,933
But that was about to change.

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00:15:20,933 --> 00:15:23,100
So, all the complex ecosystem

262
00:15:23,100 --> 00:15:26,333
that we are seeing here,
full of life,

263
00:15:26,333 --> 00:15:28,466
after

264
00:15:28,466 --> 00:15:32,600
this level, it becomes, like,
super-hard to find fossils.

265
00:15:32,600 --> 00:15:36,366
And the things that we do find
are really tiny,

266
00:15:36,366 --> 00:15:40,300
and we see how all the diversity
that we have below

267
00:15:40,300 --> 00:15:42,266
seems to have just disappeared.

268
00:15:43,866 --> 00:15:46,833
NARRATOR:
Over just a few hundred years--

269
00:15:46,833 --> 00:15:49,133
a geological blink of an eye--

270
00:15:49,133 --> 00:15:53,566
almost all life here vanishes.

271
00:15:53,566 --> 00:15:58,066
This is death
on an astounding scale.

272
00:15:59,633 --> 00:16:04,033
But curiously, these rocks
show no direct evidence

273
00:16:04,033 --> 00:16:06,700
of this volcanic activity.

274
00:16:06,700 --> 00:16:09,500
GÓMEZ CORREA:
So it's actually
really surprising

275
00:16:09,500 --> 00:16:12,533
that here we are,
thousands of miles away

276
00:16:12,533 --> 00:16:15,600
from the eruptions going on
in the north of Pangaea,

277
00:16:15,600 --> 00:16:20,600
and still you see
the consequences going on there.

278
00:16:20,600 --> 00:16:22,266
This event,

279
00:16:22,266 --> 00:16:24,533
it's not only found here,

280
00:16:24,533 --> 00:16:27,233
but also across the planet.

281
00:16:27,233 --> 00:16:29,366
Life just vanished.

282
00:16:29,366 --> 00:16:31,666
You will see this line of that.

283
00:16:31,666 --> 00:16:35,200
You will see how life
seems to just vanish.

284
00:16:35,200 --> 00:16:39,566
♪ ♪

285
00:16:39,566 --> 00:16:41,433
NARRATOR:
How could volcanic eruptions
in the north

286
00:16:41,433 --> 00:16:46,100
wipe out so much life
across the entire planet?

287
00:16:51,933 --> 00:16:53,466
Scientists think that the
Siberian Traps

288
00:16:53,466 --> 00:16:56,766
was erupted in different phases.

289
00:16:56,766 --> 00:16:59,733
Phase one was characterized
by lava flows

290
00:16:59,733 --> 00:17:03,466
for around 300,000 years.

291
00:17:03,466 --> 00:17:06,100
♪ ♪

292
00:17:06,100 --> 00:17:08,266
NARRATOR:
It's not just Earth's surface

293
00:17:08,266 --> 00:17:11,333
that is affected by
the eruptions.

294
00:17:11,333 --> 00:17:15,700
They also eject
billions upon billions

295
00:17:15,700 --> 00:17:19,533
of tons of gas and
tiny particles into the air.

296
00:17:19,533 --> 00:17:21,966
♪ ♪

297
00:17:21,966 --> 00:17:26,066
Water vapor, sulfur dioxide,

298
00:17:26,066 --> 00:17:30,266
toxic heavy metals,
and carbon dioxide,

299
00:17:30,266 --> 00:17:34,366
which begin to disperse
in the atmosphere.

300
00:17:36,233 --> 00:17:38,300
So, what we want to understand
is,

301
00:17:38,300 --> 00:17:40,300
how were these gases affecting
the planet?

302
00:17:40,300 --> 00:17:43,533
♪ ♪

303
00:17:43,533 --> 00:17:47,300
TIKOO:
Sulfur dioxide and carbon
dioxide have opposite effects

304
00:17:47,300 --> 00:17:49,000
on the Earth's atmosphere.

305
00:17:49,000 --> 00:17:51,500
Sulfur dioxide reflects sunlight

306
00:17:51,500 --> 00:17:53,300
back into outer space,

307
00:17:53,300 --> 00:17:54,633
causing global cooling,

308
00:17:54,633 --> 00:17:56,966
whereas carbon dioxide
is a greenhouse gas

309
00:17:56,966 --> 00:17:58,500
and can lead to global warming.

310
00:18:00,166 --> 00:18:03,600
NARRATOR:
The cooling and heating effects
of these gases in the atmosphere

311
00:18:03,600 --> 00:18:06,200
act on different timescales.

312
00:18:09,033 --> 00:18:11,400
Sulfur dioxide tends to stay in
the atmosphere

313
00:18:11,400 --> 00:18:12,700
for a shorter period of time,

314
00:18:12,700 --> 00:18:16,566
because it can get rained out.

315
00:18:16,566 --> 00:18:19,500
TIKOO:
But carbon dioxide can stay
in the Earth's atmosphere

316
00:18:19,500 --> 00:18:21,133
for hundreds,
if not thousands, of years.

317
00:18:21,133 --> 00:18:23,300
(rumbling)

318
00:18:23,300 --> 00:18:26,966
NARRATOR:
After each pulse or surge
of volcanic activity,

319
00:18:26,966 --> 00:18:32,833
any cooling effects from sulfur
dioxide wouldn't last long.

320
00:18:32,833 --> 00:18:35,600
But for heat-trapping
carbon dioxide,

321
00:18:35,600 --> 00:18:37,566
it's a different story.

322
00:18:39,566 --> 00:18:42,133
Carbon dioxide released during
one pulse

323
00:18:42,133 --> 00:18:44,000
of the Siberian Traps volcanism

324
00:18:44,000 --> 00:18:46,666
would have stuck around

325
00:18:46,666 --> 00:18:49,633
for the next pulse.

326
00:18:49,633 --> 00:18:53,266
NARRATOR:
And as carbon dioxide builds up
in the atmosphere,

327
00:18:53,266 --> 00:18:57,800
it affects the entire planet.

328
00:18:57,800 --> 00:19:01,833
BURGESS:
So, the biggest driver of
environmental change

329
00:19:01,833 --> 00:19:07,466
that leads to mass extinction
is not the lavas themselves.

330
00:19:07,466 --> 00:19:11,300
It's the gases that they release
into the atmosphere.

331
00:19:11,300 --> 00:19:17,033
♪ ♪

332
00:19:17,033 --> 00:19:19,066
NARRATOR:
We're witnessing the impacts

333
00:19:19,066 --> 00:19:24,633
of increasing levels
of greenhouse gases today,

334
00:19:24,633 --> 00:19:27,866
but at a much smaller scale.

335
00:19:27,866 --> 00:19:29,866
CUI:
As we are adding

336
00:19:29,866 --> 00:19:32,833
more carbon dioxide to the
atmosphere today,

337
00:19:32,833 --> 00:19:35,633
the global temperature is
rising,

338
00:19:35,633 --> 00:19:38,800
which lead to a series of
environmental changes.

339
00:19:41,266 --> 00:19:46,033
NARRATOR:
Studying our oceans and the
impacts of modern climate change

340
00:19:46,033 --> 00:19:51,366
gives clues as to how life
might have been affected

341
00:19:51,366 --> 00:19:56,366
by the warming
252 million years ago.

342
00:19:56,366 --> 00:19:58,500
We can see right now, in our own
world,

343
00:19:58,500 --> 00:19:59,933
coral reefs affected by climate
change.

344
00:19:59,933 --> 00:20:01,466
The oceans are getting warmer

345
00:20:01,466 --> 00:20:04,833
and they're getting more acidic.

346
00:20:04,833 --> 00:20:06,466
SHUKLA:
This is really stressful
for corals,

347
00:20:06,466 --> 00:20:09,533
and it causes vast swaths
of places

348
00:20:09,533 --> 00:20:11,533
like the Great Barrier Reef
to bleach,

349
00:20:11,533 --> 00:20:14,566
turning corals white.

350
00:20:14,566 --> 00:20:16,533
NARRATOR:
Bleached corals are
more likely to die,

351
00:20:16,533 --> 00:20:22,533
and this can have
devastating consequences.

352
00:20:22,533 --> 00:20:25,400
Coral reefs are a
poster child ecosystem

353
00:20:25,400 --> 00:20:27,866
for one that's complex
and full of life.

354
00:20:27,866 --> 00:20:29,766
If you start taking
away those corals,

355
00:20:29,766 --> 00:20:31,266
it's really easy to see

356
00:20:31,266 --> 00:20:32,466
how ecosystems like that can
collapse.

357
00:20:35,933 --> 00:20:38,100
NARRATOR:
But it's not just coral reefs

358
00:20:38,100 --> 00:20:39,900
that are being
pushed off balance

359
00:20:39,900 --> 00:20:43,300
by present-day climate change.

360
00:20:43,300 --> 00:20:44,900
As temperatures rise
in the ocean,

361
00:20:44,900 --> 00:20:47,500
that allows algae to
reproduce really quickly.

362
00:20:47,500 --> 00:20:49,400
And when it rains,

363
00:20:49,400 --> 00:20:53,400
that pushes nutrients that
we have on land into the ocean,

364
00:20:53,400 --> 00:20:55,933
and the algae
feed on that and grow,

365
00:20:55,933 --> 00:20:58,833
resulting in these
enormous algal blooms.

366
00:20:58,833 --> 00:21:01,100
♪ ♪

367
00:21:01,100 --> 00:21:03,366
NARRATOR:
These vast algal blooms today

368
00:21:03,366 --> 00:21:05,533
have consequences for
life in the oceans.

369
00:21:07,366 --> 00:21:08,866
And in this case,

370
00:21:08,866 --> 00:21:11,100
it's not the rising
temperatures that kill.

371
00:21:12,733 --> 00:21:14,733
As algal blooms occur,

372
00:21:14,733 --> 00:21:17,066
they actually take up the oxygen
in the ocean,

373
00:21:17,066 --> 00:21:18,533
leaving less oxygen behind,

374
00:21:18,533 --> 00:21:21,866
and therefore, organisms
can't live in it.

375
00:21:21,866 --> 00:21:25,533
NARRATOR:
Changes in modern-day ecosystems

376
00:21:25,533 --> 00:21:29,666
show how the process
of extinction can play out.

377
00:21:29,666 --> 00:21:31,933
FORMOSO:
So, these subtle changes

378
00:21:31,933 --> 00:21:34,466
may not seem
so striking at first:

379
00:21:34,466 --> 00:21:36,400
the loss of one species here,

380
00:21:36,400 --> 00:21:38,966
the change in this environment
over there.

381
00:21:38,966 --> 00:21:40,766
But given enough time

382
00:21:40,766 --> 00:21:42,766
and given enough of these
subtle changes,

383
00:21:42,766 --> 00:21:47,033
you can have drastic
negative impacts on ecosystems.

384
00:21:49,733 --> 00:21:52,300
This slow relentless change
is likely what led to

385
00:21:52,300 --> 00:21:54,500
the huge loss of life
at the end of the Permian.

386
00:21:54,500 --> 00:21:57,533
♪ ♪

387
00:21:57,533 --> 00:22:01,666
NARRATOR:
Mass extinction can
take place slowly

388
00:22:01,666 --> 00:22:05,333
over thousands or
even millions of years,

389
00:22:05,333 --> 00:22:08,300
as environmental changes
become too much

390
00:22:08,300 --> 00:22:10,366
for many species to adapt to.

391
00:22:10,366 --> 00:22:15,033
♪ ♪

392
00:22:19,966 --> 00:22:24,366
In Pangaea,
as greenhouse gases build up

393
00:22:24,366 --> 00:22:26,833
over hundreds of thousands
of years,

394
00:22:26,833 --> 00:22:29,600
the temperature rises.

395
00:22:29,600 --> 00:22:30,966
MONARREZ:
During the mass extinction,

396
00:22:30,966 --> 00:22:33,033
it is thought
the ocean warmed up

397
00:22:33,033 --> 00:22:35,633
between 14 and 18 degrees
Fahrenheit,

398
00:22:35,633 --> 00:22:39,933
and on land,
they warmed up even more.

399
00:22:39,933 --> 00:22:45,366
NARRATOR:
On the supercontinent,
trees begin to die.

400
00:22:45,366 --> 00:22:51,266
(trunk cracking slowly)

401
00:22:54,533 --> 00:22:56,533
(creaking)

402
00:22:56,533 --> 00:22:58,966
♪ ♪

403
00:22:58,966 --> 00:23:03,266
Holes appear in the canopy,

404
00:23:03,266 --> 00:23:06,500
bathing the ground in sunlight.

405
00:23:10,266 --> 00:23:14,933
For some life,
it's an opportunity.

406
00:23:14,933 --> 00:23:17,633
Weed-like lycophyte plants

407
00:23:17,633 --> 00:23:20,766
flourish in this new
environment.

408
00:23:22,966 --> 00:23:25,233
And with the
warmer temperatures,

409
00:23:25,233 --> 00:23:29,266
other species migrate.

410
00:23:33,433 --> 00:23:37,666
Woody, seed-bearing plants
called cycads

411
00:23:37,666 --> 00:23:40,100
that are believed to have
once grown in the tropics

412
00:23:40,100 --> 00:23:44,333
now thrive closer to the poles.

413
00:23:44,333 --> 00:23:46,500
♪ ♪

414
00:23:46,500 --> 00:23:50,166
Fossil evidence suggests
that some ecosystems

415
00:23:50,166 --> 00:23:54,433
are now more diverse
than before the warming began.

416
00:23:54,433 --> 00:23:59,500
♪ ♪

417
00:23:59,500 --> 00:24:03,100
But this ecosystem
is still vulnerable.

418
00:24:05,400 --> 00:24:10,000
A few more degrees of warming
and it could crumble.

419
00:24:13,000 --> 00:24:17,033
♪ ♪

420
00:24:19,633 --> 00:24:24,500
But then,
something strange happens.

421
00:24:24,500 --> 00:24:28,433
A silence descends
on the Siberian Traps.

422
00:24:28,433 --> 00:24:33,933
♪ ♪

423
00:24:33,933 --> 00:24:36,800
Greenhouse gas emissions,

424
00:24:36,800 --> 00:24:40,933
including carbon dioxide,
taper off.

425
00:24:40,933 --> 00:24:46,266
After 300,000 years
of lava flows,

426
00:24:46,266 --> 00:24:49,533
the eruptions finally stop.

427
00:24:52,233 --> 00:24:54,566
For now.

428
00:24:54,566 --> 00:24:59,666
♪ ♪

429
00:24:59,666 --> 00:25:02,766
When scientists try
to calculate the amount of

430
00:25:02,766 --> 00:25:07,133
greenhouse gases
released by the eruptions,

431
00:25:07,133 --> 00:25:09,800
and then compare that to
the amount of global warming

432
00:25:09,800 --> 00:25:13,000
implied in the rock record,

433
00:25:13,000 --> 00:25:15,900
something doesn't add up.

434
00:25:17,333 --> 00:25:18,533
When we add up all the carbon

435
00:25:18,533 --> 00:25:21,066
we think we would have got
from the magmas,

436
00:25:21,066 --> 00:25:22,933
making our best guess,

437
00:25:22,933 --> 00:25:26,900
it's not enough to account for
the level of climate devastation

438
00:25:26,900 --> 00:25:29,566
that the geological
record suggests.

439
00:25:29,566 --> 00:25:31,833
♪ ♪

440
00:25:31,833 --> 00:25:34,933
BURGESS:
About half of the
greenhouse gases

441
00:25:34,933 --> 00:25:37,366
needed to drive the
extinction to

442
00:25:37,366 --> 00:25:39,833
the end of the Permian
are missing.

443
00:25:41,633 --> 00:25:45,933
NARRATOR:
So, where do all the extra
greenhouse gases come from?

444
00:25:45,933 --> 00:25:49,200
♪ ♪

445
00:25:49,200 --> 00:25:53,100
One answer
can be found underground.

446
00:25:55,700 --> 00:26:01,266
♪ ♪

447
00:26:01,266 --> 00:26:05,500
It's quiet on the surface.

448
00:26:06,766 --> 00:26:11,033
But beneath
the Siberian lava field...

449
00:26:13,933 --> 00:26:17,066
...reaching
almost eight miles deep...

450
00:26:20,400 --> 00:26:23,866
...hot magma still flows,

451
00:26:23,866 --> 00:26:28,466
forming great
reservoirs underground,

452
00:26:28,466 --> 00:26:32,400
encountering rocks hundreds
of millions of years old

453
00:26:32,400 --> 00:26:34,566
deep below.

454
00:26:39,333 --> 00:26:42,433
The amount of lava that,
over time,

455
00:26:42,433 --> 00:26:43,700
was released from the Siberian
Traps

456
00:26:43,700 --> 00:26:45,266
was so immense

457
00:26:45,266 --> 00:26:47,533
that it caps the Earth's surface
eventually.

458
00:26:50,733 --> 00:26:53,400
 
NARRATOR:
After 300,000 years of lava

459
00:26:53,400 --> 00:26:55,666
building up on Earth's surface,

460
00:26:55,666 --> 00:26:59,200
the path of the magma changes.

461
00:27:01,666 --> 00:27:05,300
The volcanism enters phase two.

462
00:27:06,900 --> 00:27:10,233
BURGESS:
Instead of lavas flowing
on the surface,

463
00:27:10,233 --> 00:27:13,100
magma started
to spread laterally underground.

464
00:27:15,966 --> 00:27:18,100
MATHER:
The Earth's crust is
in some ways

465
00:27:18,100 --> 00:27:19,900
like a layer cake.

466
00:27:19,900 --> 00:27:22,433
So as the magma forced its way
up,

467
00:27:22,433 --> 00:27:24,500
it encountered different layers
of rock.

468
00:27:24,500 --> 00:27:28,366
♪ ♪

469
00:27:28,366 --> 00:27:30,633
NARRATOR:
One such rock was coal.

470
00:27:30,633 --> 00:27:32,566
WHITESIDE:
In this case,
the magma literally

471
00:27:32,566 --> 00:27:34,700
started burning fossil fuels

472
00:27:34,700 --> 00:27:36,266
similar to the way we're burning
them

473
00:27:36,266 --> 00:27:37,866
through our pistons and power
plants.

474
00:27:40,433 --> 00:27:44,133
NARRATOR:
But carbon dioxide
doesn't act alone.

475
00:27:45,333 --> 00:27:48,766
It isn't just coal
in the Earth's crust.

476
00:27:50,100 --> 00:27:52,566
TIKOO:
Beneath the volcanic rocks
released

477
00:27:52,566 --> 00:27:54,333
by the Siberian Traps eruptions

478
00:27:54,333 --> 00:27:57,933
lies an ancient seabed that
contains the salt

479
00:27:57,933 --> 00:28:01,033
 
left behind
whenever the sea dried up.

480
00:28:03,000 --> 00:28:04,600
In some places, the salt layers

481
00:28:04,600 --> 00:28:07,033
were 650 feet thick.

482
00:28:07,033 --> 00:28:09,166
Now, that's quite a lot of salt.

483
00:28:10,533 --> 00:28:14,166
 
NARRATOR:
When salt and magma
make contact,

484
00:28:14,166 --> 00:28:17,900
the consequences
can be devastating.

485
00:28:19,533 --> 00:28:22,000
So, salt is-- I have a piece
with me here.

486
00:28:22,000 --> 00:28:24,933
 
On its own, salt's
a fairly sort of innocuous,

487
00:28:24,933 --> 00:28:28,100
not very dangerous-looking
rock type, as we know.

488
00:28:28,100 --> 00:28:29,733
We put salt on our food
and so on.

489
00:28:29,733 --> 00:28:32,066
But it can be very dangerous.

490
00:28:32,066 --> 00:28:34,500
So, when the hot magma comes
into contact

491
00:28:34,500 --> 00:28:37,000
with these salt layers,
it, it bakes them,

492
00:28:37,000 --> 00:28:40,966
releasing all
sorts of horrible gases.

493
00:28:40,966 --> 00:28:42,966
TIKOO:
The burning coal

494
00:28:42,966 --> 00:28:45,933
and the heated-up deposits
of salt

495
00:28:45,933 --> 00:28:48,066
that were
triggered by these eruptions

496
00:28:48,066 --> 00:28:50,533
just basically
created a huge time bomb.

497
00:28:52,666 --> 00:28:55,600
♪ ♪

498
00:28:57,833 --> 00:29:00,333
NARRATOR:
The salt and coal underground
are heated

499
00:29:00,333 --> 00:29:03,833
to as much as
1,400 degrees Fahrenheit.

500
00:29:06,300 --> 00:29:10,033
And begin to release
their toxins.

501
00:29:12,233 --> 00:29:15,933
The pressure
beneath the surface increases.

502
00:29:17,933 --> 00:29:21,566
Until the land
above can take no more.

503
00:29:22,533 --> 00:29:25,666
(rock cracking)

504
00:29:27,433 --> 00:29:33,933
♪ ♪

505
00:29:33,933 --> 00:29:36,733
(eruption roars)

506
00:29:36,733 --> 00:29:40,700
Volcanic material
flies miles into the air.

507
00:29:43,433 --> 00:29:46,566
Each eruption releases more
greenhouse gases

508
00:29:46,566 --> 00:29:48,833
from burning coal.

509
00:29:51,366 --> 00:29:54,466
This is thought to be
the missing link that accounts

510
00:29:54,466 --> 00:29:58,700
for the full extent
of global temperature rise.

511
00:30:00,066 --> 00:30:04,933
And the scorching salt
releases deadly chemicals, too.

512
00:30:06,633 --> 00:30:10,933
Toxic gases called halogens,

513
00:30:10,933 --> 00:30:14,000
which can spell trouble
if they reach the ozone layer.

514
00:30:17,266 --> 00:30:19,300
WIGNALL:
It's a layer high in our
atmosphere,

515
00:30:19,300 --> 00:30:21,366
and what it does is,

516
00:30:21,366 --> 00:30:23,833
it protects our planet
from ultraviolet radiation

517
00:30:23,833 --> 00:30:27,200
from the sun, which is
very harmful for all life.

518
00:30:27,200 --> 00:30:28,900
SINGH:
When these halogens react
with the ozone layer,

519
00:30:28,900 --> 00:30:30,566
they weaken it,

520
00:30:30,566 --> 00:30:32,800
and that allows harmful
radiation

521
00:30:32,800 --> 00:30:35,300
from the sun to come through.

522
00:30:37,133 --> 00:30:40,233
 
NARRATOR:
We've seen the Earth's
ozone layer temporarily degraded

523
00:30:40,233 --> 00:30:43,033
in recent history.

524
00:30:43,033 --> 00:30:45,233
In the 1980s,

525
00:30:45,233 --> 00:30:48,100
industrial activity created
a hole in the ozone layer

526
00:30:48,100 --> 00:30:51,600
over Antarctica.

527
00:30:51,600 --> 00:30:53,300
One that is now closing.

528
00:30:56,333 --> 00:30:59,700
But during the extinction event
at the end of the Permian,

529
00:30:59,700 --> 00:31:01,433
the halogens damaged

530
00:31:01,433 --> 00:31:06,433
the ozone layer
on a devastating scale,

531
00:31:06,433 --> 00:31:09,000
bathing life with a massive dose

532
00:31:09,000 --> 00:31:12,066
of harmful
ultraviolet radiation.

533
00:31:21,900 --> 00:31:23,966
The loss of ozone is thought

534
00:31:23,966 --> 00:31:26,800
to have contributed
to the extinctions.

535
00:31:27,900 --> 00:31:30,800
But can scientists
find a way to prove it?

536
00:31:32,633 --> 00:31:34,866
BENCA:
A way we can really understand

537
00:31:34,866 --> 00:31:36,600
the mass extinction is by
looking at

538
00:31:36,600 --> 00:31:38,166
fossilized pollen grains,

539
00:31:38,166 --> 00:31:40,233
microscopic
reproductive structures

540
00:31:40,233 --> 00:31:42,533
plants left behind
in the fossil record.

541
00:31:44,766 --> 00:31:48,800
NARRATOR:
Some tree pollen has remained
relatively unchanged

542
00:31:48,800 --> 00:31:50,866
for hundreds of millions
of years.

543
00:31:53,266 --> 00:31:55,966
So modern-day pollen
should look the same

544
00:31:55,966 --> 00:31:59,566
as that in the fossil record.

545
00:31:59,566 --> 00:32:00,966
So, I have a picture here

546
00:32:00,966 --> 00:32:04,600
of a modern pollen grain
of a pine tree.

547
00:32:04,600 --> 00:32:06,466
It's basically one central body,

548
00:32:06,466 --> 00:32:08,833
and there are these two
structures on the side

549
00:32:08,833 --> 00:32:10,766
that are called sacci.

550
00:32:10,766 --> 00:32:14,466
These help this grain
catch the wind and fly.

551
00:32:14,466 --> 00:32:16,666
And this is very much what
the pollen grains

552
00:32:16,666 --> 00:32:19,000
in the end-Permian trees would
have looked like

553
00:32:19,000 --> 00:32:20,400
under normal conditions.

554
00:32:22,000 --> 00:32:24,600
NARRATOR:
But the fossil pollen from
the extinction event

555
00:32:24,600 --> 00:32:26,900
doesn't look the same.

556
00:32:29,100 --> 00:32:32,066
So, during the mass extinction
at the end of the Permian,

557
00:32:32,066 --> 00:32:34,800
the pollen grains start looking
more like this,

558
00:32:34,800 --> 00:32:37,333
and, boy, they're strange.

559
00:32:37,333 --> 00:32:42,100
This one here has three
sacci when it should have two.

560
00:32:42,100 --> 00:32:43,566
And this one has four sacci.

561
00:32:43,566 --> 00:32:47,466
This here is two grains
that are stuck together.

562
00:32:47,466 --> 00:32:49,166
They come in all sorts

563
00:32:49,166 --> 00:32:52,500
of strange shapes and forms
that really deviate

564
00:32:52,500 --> 00:32:54,300
from what a healthy pollen grain
should look like.

565
00:32:54,300 --> 00:32:57,300
They're malformations.

566
00:32:59,366 --> 00:33:02,833
NARRATOR:
Could increased ultraviolet
radiation be the cause?

567
00:33:04,766 --> 00:33:06,266
To find out,

568
00:33:06,266 --> 00:33:09,866
paleobotanist Jeffrey Benca
grew modern pine trees

569
00:33:09,866 --> 00:33:12,733
under high ultraviolet
radiation in a lab.

570
00:33:14,366 --> 00:33:15,800
BENCA:
We wondered if the plants

571
00:33:15,800 --> 00:33:18,666
would just die on us
under these extreme conditions.

572
00:33:18,666 --> 00:33:21,466
But that's not what we found.

573
00:33:21,466 --> 00:33:24,100
Instead, we found the exact
same types of malformations

574
00:33:24,100 --> 00:33:28,833
in the fossil record were
produced by our modern pines.

575
00:33:30,033 --> 00:33:32,566
NARRATOR:
Although this high
ultraviolet radiation

576
00:33:32,566 --> 00:33:35,000
didn't kill the plants outright,

577
00:33:35,000 --> 00:33:39,700
malformations in the pollen did
have catastrophic consequences.

578
00:33:41,800 --> 00:33:44,100
The results of this experiment
are telling us

579
00:33:44,100 --> 00:33:46,066
that at the end of the Permian,

580
00:33:46,066 --> 00:33:48,233
the forests would
have been sterilized,

581
00:33:48,233 --> 00:33:50,033
unable to reproduce.

582
00:33:53,600 --> 00:33:57,033
NARRATOR:
It is a slow march
to extinction.

583
00:34:00,533 --> 00:34:05,666
♪ ♪

584
00:34:05,666 --> 00:34:07,833
The Permian forests
have been exposed

585
00:34:07,833 --> 00:34:11,566
to extreme
ultraviolet radiation.

586
00:34:16,100 --> 00:34:20,233
Healthy-looking trees
are now sterile.

587
00:34:20,233 --> 00:34:26,333
♪ ♪

588
00:34:26,333 --> 00:34:29,266
As trees die
and are not replaced,

589
00:34:29,266 --> 00:34:34,700
animals lose precious habitat
and food supplies dwindle.

590
00:34:36,033 --> 00:34:41,466
♪ ♪

591
00:34:41,466 --> 00:34:43,766
During the mass extinction,

592
00:34:43,766 --> 00:34:47,866
life on land is
under threat from all sides.

593
00:34:49,233 --> 00:34:51,166
The mass extinction at the end
of the Permian

594
00:34:51,166 --> 00:34:53,266
is like
"Murder on the Orient Express."

595
00:34:53,266 --> 00:34:57,533
There's not one killer
that can do it all.

596
00:34:57,533 --> 00:34:59,100
SINGH:
There's still a lot of debate

597
00:34:59,100 --> 00:35:00,700
about how all these killers came
together

598
00:35:00,700 --> 00:35:02,133
to kill off life on land.

599
00:35:02,133 --> 00:35:04,866
We're talking global warming,
heavy metal poisoning,

600
00:35:04,866 --> 00:35:09,766
acid rain, wild fires,
deadly U.V. radiation.

601
00:35:09,766 --> 00:35:11,533
This was hell on Earth.

602
00:35:11,533 --> 00:35:13,800
♪ ♪

603
00:35:13,800 --> 00:35:16,366
BENCA:
There probably were pulses
of ozone weakening

604
00:35:16,366 --> 00:35:18,733
that were happening throughout
the duration

605
00:35:18,733 --> 00:35:21,100
of the Siberian Traps activity,

606
00:35:21,100 --> 00:35:23,966
but over even longer time spans,

607
00:35:23,966 --> 00:35:26,966
global warming was kicking in

608
00:35:26,966 --> 00:35:30,100
and really driving
ecosystems to full collapse.

609
00:35:32,033 --> 00:35:34,400
NARRATOR:
The collapse
of life in the oceans

610
00:35:34,400 --> 00:35:36,666
is even more dramatic.

611
00:35:39,333 --> 00:35:43,566
The warmer, nutrient-rich waters
contain less oxygen.

612
00:35:45,366 --> 00:35:51,666
Oxygen that marine life
uses to breathe.

613
00:35:51,666 --> 00:35:55,000
And as carbon dioxide reacts
with seawater,

614
00:35:55,000 --> 00:35:59,433
the oceans become more acidic.

615
00:35:59,433 --> 00:36:03,966
Algae and bacteria bloom
across the planet,

616
00:36:03,966 --> 00:36:09,500
poisoning the oceans with the
hydrogen sulfide they release.

617
00:36:10,900 --> 00:36:14,300
Creatures across the oceans die.

618
00:36:17,500 --> 00:36:22,466
Huge stretches of the seafloor
become fetid beds of death.

619
00:36:26,533 --> 00:36:28,166
MONARREZ:
So, in the oceans,

620
00:36:28,166 --> 00:36:30,933
the combination of increases
in temperature,

621
00:36:30,933 --> 00:36:33,966
loss of oxygen, and
acidification

622
00:36:33,966 --> 00:36:36,700
 
all contributed to the loss of
life

623
00:36:36,700 --> 00:36:40,033
we see at the end of the
Permian.

624
00:36:40,033 --> 00:36:42,300
These ocean killers could have
worked together

625
00:36:42,300 --> 00:36:45,033
to be exceptionally devastating
to ocean life.

626
00:36:45,033 --> 00:36:49,966
NARRATOR:
Exactly how much life
died is debated by scientists,

627
00:36:49,966 --> 00:36:54,433
because the fossil
record is incomplete.

628
00:36:54,433 --> 00:36:56,000
But evidence shows

629
00:36:56,000 --> 00:36:58,566
that the great Glossopteris
forests,

630
00:36:58,566 --> 00:37:01,700
the giant sabertooth predators,

631
00:37:01,700 --> 00:37:05,800
and almost
all marine life disappears.

632
00:37:05,800 --> 00:37:07,966
♪ ♪

633
00:37:07,966 --> 00:37:11,400
By the time
the eruptions finally stop,

634
00:37:11,400 --> 00:37:13,966
the average global
atmospheric temperature

635
00:37:13,966 --> 00:37:19,133
has risen as much
as 22 degrees Fahrenheit.

636
00:37:23,666 --> 00:37:27,600
Countless species have gone.

637
00:37:27,600 --> 00:37:32,466
The rich complexity
of life on Earth has vanished.

638
00:37:32,466 --> 00:37:34,966
The words "mass extinction"
are not

639
00:37:34,966 --> 00:37:37,166
lightly put together by
scientists.

640
00:37:37,166 --> 00:37:40,066
They carry real weight.

641
00:37:40,066 --> 00:37:42,966
And the extinction
at the end of the Permian

642
00:37:42,966 --> 00:37:45,933
was the most
severe of all of these.

643
00:37:48,333 --> 00:37:50,500
It's been called the mother of
mass extinctions,

644
00:37:50,500 --> 00:37:52,366
it's been called the Great
Dying.

645
00:37:52,366 --> 00:37:54,500
It's, it's by far the worst
thing

646
00:37:54,500 --> 00:37:57,000
that's, that life has ever had
to endure.

647
00:37:57,000 --> 00:38:00,566
♪ ♪

648
00:38:00,566 --> 00:38:03,433
NARRATOR:
With so much death
and destruction,

649
00:38:03,433 --> 00:38:07,100
how could any
life hold on at all?

650
00:38:09,266 --> 00:38:12,733
Life on Earth is adapted to
living on Earth.

651
00:38:12,733 --> 00:38:14,500
It has evolved that way.

652
00:38:14,500 --> 00:38:16,100
And if circumstances change,

653
00:38:16,100 --> 00:38:19,333
organisms can adapt
to that change.

654
00:38:19,333 --> 00:38:21,233
(hisses)

655
00:38:21,233 --> 00:38:23,500
And those that cannot adapt
will eventually go extinct.

656
00:38:23,500 --> 00:38:26,300
♪ ♪

657
00:38:26,300 --> 00:38:29,400
NARRATOR:
If species can adapt
to the new conditions,

658
00:38:29,400 --> 00:38:32,933
it gives them
an opportunity to thrive.

659
00:38:35,933 --> 00:38:39,066
Death and extinction shape
the evolution of life.

660
00:38:39,066 --> 00:38:40,466
It's through this act

661
00:38:40,466 --> 00:38:42,800
of creative destruction,
where one species go extinct,

662
00:38:42,800 --> 00:38:47,000
that allows for another species
to actually rise.

663
00:38:47,000 --> 00:38:50,666
Over time, the combination
of these interactions,

664
00:38:50,666 --> 00:38:56,066
of extinction,
adaptation, and evolution,

665
00:38:56,066 --> 00:38:58,966
create resilient ecosystems.

666
00:39:02,600 --> 00:39:08,066
NARRATOR:
But even resilient ecosystems
aren't indestructible.

667
00:39:08,066 --> 00:39:11,333
An ecosystem is a lot like a
Jenga tower,

668
00:39:11,333 --> 00:39:14,266
where each brick is its own
species.

669
00:39:14,266 --> 00:39:16,733
And as you remove one to two
species,

670
00:39:16,733 --> 00:39:19,066
 
the ecosystem
stays relatively intact.

671
00:39:19,066 --> 00:39:21,133
But the more species you lose,

672
00:39:21,133 --> 00:39:23,633
the more unstable
the ecosystem becomes

673
00:39:23,633 --> 00:39:27,200
until it fully collapses.

674
00:39:27,200 --> 00:39:28,800
PEECOOK:
Today, organisms are really
struggling

675
00:39:28,800 --> 00:39:31,166
to adapt to
an ever-changing planet.

676
00:39:34,300 --> 00:39:36,966
SHUKLA:
And it's not
just climate change.

677
00:39:36,966 --> 00:39:38,966
It's also things
like habitat destruction.

678
00:39:40,766 --> 00:39:44,533
Loss of coral reefs,
loss of sea ice.

679
00:39:44,533 --> 00:39:47,366
Deforestation.

680
00:39:47,366 --> 00:39:48,633
Loss of wetlands.

681
00:39:48,633 --> 00:39:50,600
Loss of grasslands and prairies.

682
00:39:53,200 --> 00:39:55,700
NARRATOR:
But even after ecosystems
collapse,

683
00:39:55,700 --> 00:40:00,400
like they did 252 million
years ago,

684
00:40:00,400 --> 00:40:03,500
some life survives.

685
00:40:03,500 --> 00:40:08,266
If it can adapt,
there's a chance to rebuild.

686
00:40:10,333 --> 00:40:14,100
♪ ♪

687
00:40:14,100 --> 00:40:19,466
The Permian apocalypse
isn't just the end of one world.

688
00:40:19,466 --> 00:40:21,833
It's the beginning of a new one.

689
00:40:26,166 --> 00:40:28,633
♪ ♪

690
00:40:28,633 --> 00:40:31,566
Fossil evidence is patchy,

691
00:40:31,566 --> 00:40:36,866
so scientists don't know
exactly where life holds on.

692
00:40:36,866 --> 00:40:42,933
On land, some life likely
survived near the cooler poles.

693
00:40:42,933 --> 00:40:47,800
And many creatures could
have sought refuge underground,

694
00:40:47,800 --> 00:40:50,166
sheltering from
blistering temperatures

695
00:40:50,166 --> 00:40:52,866
and intense solar radiation.

696
00:40:55,300 --> 00:40:58,200
And some life
survives above ground, too.

697
00:41:01,400 --> 00:41:03,600
A single type of plant dominates

698
00:41:03,600 --> 00:41:06,600
much of the post-extinction
landscape.

699
00:41:09,600 --> 00:41:12,533
Pleuromeia.

700
00:41:12,533 --> 00:41:16,366
A hardy plant that makes
it through the apocalypse.

701
00:41:18,933 --> 00:41:20,933
This ecosystem provides

702
00:41:20,933 --> 00:41:23,266
just enough sustenance
for the cockroaches,

703
00:41:23,266 --> 00:41:28,033
who also make it through.

704
00:41:28,033 --> 00:41:32,533
Life endures.

705
00:41:32,533 --> 00:41:35,033
But the searing heat does, too.

706
00:41:38,233 --> 00:41:40,333
The period immediately
after the Permian

707
00:41:40,333 --> 00:41:43,300
is the Triassic period,
and it was very, very hot.

708
00:41:45,066 --> 00:41:47,200
NARRATOR:
Scientists know about these
conditions

709
00:41:47,200 --> 00:41:48,700
from studying fossils

710
00:41:48,700 --> 00:41:52,600
and the chemical composition
of rocks formed at the time.

711
00:41:54,133 --> 00:41:55,800
It's incredible what we can get
from rocks.

712
00:41:55,800 --> 00:41:57,333
They look so unassuming, but
actually,

713
00:41:57,333 --> 00:41:58,800
they hold so many clues

714
00:41:58,800 --> 00:42:00,266
to past environments and past
life.

715
00:42:03,366 --> 00:42:06,400
LOOY:
We, for instance, know that
there were forests growing

716
00:42:06,400 --> 00:42:09,533
on the South Pole,
and to make that happen,

717
00:42:09,533 --> 00:42:11,600
you need a warm planet.

718
00:42:14,800 --> 00:42:18,666
WHITESIDE:
Temperatures on land would be
120 degrees Fahrenheit,

719
00:42:18,666 --> 00:42:21,600
possibly up to 140,
with heat waves on top of that.

720
00:42:24,200 --> 00:42:27,900
LOOY:
And that is so hot that in
several places of the world,

721
00:42:27,900 --> 00:42:30,566
complex life would
not have been possible anymore.

722
00:42:32,500 --> 00:42:35,000
NARRATOR:
It's also hot in the oceans.

723
00:42:36,900 --> 00:42:39,633
Surface ocean temperature may
have reached as high

724
00:42:39,633 --> 00:42:41,833
as 100 degree Fahrenheit,

725
00:42:41,833 --> 00:42:46,600
and that's as hot as a hot tub.

726
00:42:46,600 --> 00:42:48,600
These extreme ocean temperatures
would have been

727
00:42:48,600 --> 00:42:50,233
inhospitable to most ocean life.

728
00:42:52,666 --> 00:42:54,700
MONARREZ:
The mass extinction at the end
of the Permian

729
00:42:54,700 --> 00:42:57,300
was so devastating
to coral reefs

730
00:42:57,300 --> 00:43:01,100
that for about 14 million years
into the Triassic,

731
00:43:01,100 --> 00:43:04,766
we don't see corals
anywhere on the planet.

732
00:43:08,066 --> 00:43:12,066
NARRATOR:
For life to bounce back,
the planet needs to cool down.

733
00:43:14,466 --> 00:43:18,833
♪ ♪

734
00:43:18,833 --> 00:43:22,266
Normally, over vast timescales,

735
00:43:22,266 --> 00:43:27,433
Earth's temperature
naturally resets itself.

736
00:43:27,433 --> 00:43:31,000
Carbon dioxide
is removed from the atmosphere,

737
00:43:31,000 --> 00:43:35,400
in part by
reacting with rainwater.

738
00:43:35,400 --> 00:43:39,100
But vast areas of
Central Pangaea are desert.

739
00:43:41,766 --> 00:43:43,300
Little rain falls.

740
00:43:46,400 --> 00:43:50,633
It takes millions
of years for Earth to cool.

741
00:43:50,633 --> 00:43:55,666
♪ ♪

742
00:43:57,900 --> 00:44:02,333
Much of the supercontinent
remains barren and dry.

743
00:44:03,500 --> 00:44:09,066
But 18 million years
after the mass extinction began,

744
00:44:09,066 --> 00:44:13,800
life is about
to get an enormous boost.

745
00:44:13,800 --> 00:44:16,300
(thunder rumbling)

746
00:44:16,300 --> 00:44:21,033
And traces of what that was
can still be seen today.

747
00:44:22,966 --> 00:44:27,133
♪ ♪

748
00:44:34,966 --> 00:44:39,533
These mountains are largely made
of a hard rock called dolomite.

749
00:44:41,133 --> 00:44:42,566
But hidden within them

750
00:44:42,566 --> 00:44:46,100
are layers of an altogether
different rock.

751
00:44:47,500 --> 00:44:49,933
One that holds clues

752
00:44:49,933 --> 00:44:53,466
to an extraordinary time
in Earth's history.

753
00:44:55,266 --> 00:44:57,066
EVELYN KUSTATSCHER:
This is the rock that formed

754
00:44:57,066 --> 00:44:59,800
during this strange period
of time.

755
00:44:59,800 --> 00:45:01,500
This is a sandstone.

756
00:45:01,500 --> 00:45:04,600
It's a relatively soft stone,
and you can see

757
00:45:04,600 --> 00:45:07,600
all the single grains
of the sand.

758
00:45:08,866 --> 00:45:11,300
And if we take this ones
in here,

759
00:45:11,300 --> 00:45:13,766
this is a softer stone still,

760
00:45:13,766 --> 00:45:16,066
and it easily breaks down
in my fingers,

761
00:45:16,066 --> 00:45:19,933
because it's a mudstone.

762
00:45:19,933 --> 00:45:22,666
These rocks in here are looking
completely different

763
00:45:22,666 --> 00:45:24,633
from the ones below and above
us,

764
00:45:24,633 --> 00:45:27,500
because these are sandstones
and mudstones,

765
00:45:27,500 --> 00:45:29,733
whereas those above and below
are dolomites.

766
00:45:31,066 --> 00:45:34,400
NARRATOR:
The secret of this unusual layer
of rock

767
00:45:34,400 --> 00:45:36,666
is how it was formed.

768
00:45:39,133 --> 00:45:42,133
Sandstones and mudstones
are sediments

769
00:45:42,133 --> 00:45:43,933
that are typically formed

770
00:45:43,933 --> 00:45:47,533
by the erosion of sand and mud
on the continents

771
00:45:47,533 --> 00:45:51,200
which were
washed into the ocean.

772
00:45:52,600 --> 00:45:54,233
NARRATOR:
All over the Dolomites,

773
00:45:54,233 --> 00:45:55,900
there are examples of this

774
00:45:55,900 --> 00:45:59,500
strange layer of softer rocks
made from sand and mud.

775
00:46:02,300 --> 00:46:04,500
KUSTATSCHER:
So now, of course,
we have to ask ourself,

776
00:46:04,500 --> 00:46:06,500
what caused
this dramatic change?

777
00:46:09,200 --> 00:46:13,100
NARRATOR:
The answer came from the sky.

778
00:46:13,100 --> 00:46:16,400
And it was rain, a lot of rain.

779
00:46:16,400 --> 00:46:18,600
This episode
lasted for a long time.

780
00:46:18,600 --> 00:46:20,766
About two million years.

781
00:46:22,866 --> 00:46:25,600
NARRATOR:
A deluge on this scale seems
so unlikely

782
00:46:25,600 --> 00:46:28,433
that when scientists
first discovered the evidence,

783
00:46:28,433 --> 00:46:33,866
some believed
it was just a local event.

784
00:46:33,866 --> 00:46:36,366
KUSTATSCHER:
But later on,
evidence of it popped up

785
00:46:36,366 --> 00:46:39,533
also at China,
Iran, North America.

786
00:46:39,533 --> 00:46:44,100
So nowadays, it is
believed to be a global event.

787
00:46:44,100 --> 00:46:48,566
This period of time is called
the Carnian Pluvial Episode.

788
00:46:51,666 --> 00:46:54,233
(thunder rumbling)

789
00:46:59,100 --> 00:47:02,633
NARRATOR:
18 million years after
the mass extinction began,

790
00:47:02,633 --> 00:47:06,633
the skies become heavy
with moisture...

791
00:47:09,433 --> 00:47:11,466
...until the clouds burst.

792
00:47:11,466 --> 00:47:14,300
(rain falling, thunder rumbling)

793
00:47:14,300 --> 00:47:17,233
Rain falls across Pangaea.

794
00:47:19,866 --> 00:47:23,366
And Earth is changed once more.

795
00:47:23,366 --> 00:47:25,533
♪ ♪

796
00:47:25,533 --> 00:47:28,266
Lush forests grow again.

797
00:47:30,533 --> 00:47:33,800
This two-million-year event
lasted just as long

798
00:47:33,800 --> 00:47:37,466
as the volcanism
that preceded it

799
00:47:37,466 --> 00:47:42,400
and may have marked
the rise of a new life form.

800
00:47:42,400 --> 00:47:44,766
The Carnian Pluvial Episode set
the stage

801
00:47:44,766 --> 00:47:46,766
for the dawn of the age
of dinosaurs.

802
00:47:46,766 --> 00:47:50,966
♪ ♪

803
00:47:50,966 --> 00:47:54,466
SINGH:
My research suggests that this
era of warm,

804
00:47:54,466 --> 00:47:57,533
wet conditions really boosted
plant diversity.

805
00:47:57,533 --> 00:48:00,133
And from the plants, we get

806
00:48:00,133 --> 00:48:02,033
more herbivores,
more carnivores,

807
00:48:02,033 --> 00:48:05,466
and dinosaurs are
part of that growth.

808
00:48:05,466 --> 00:48:08,900
So, this is Herrerasaurus, this
is one of the first dinosaurs

809
00:48:08,900 --> 00:48:11,633
to appear just after
the Carnian Pluvial Episode,

810
00:48:11,633 --> 00:48:14,466
and as you can see by
the sharp teeth here,

811
00:48:14,466 --> 00:48:18,200
this was a meat-eater,
one of the top predators.

812
00:48:18,200 --> 00:48:20,066
The Carnian Pluvial Episode,

813
00:48:20,066 --> 00:48:21,700
and what it might have meant
for dinosaurs,

814
00:48:21,700 --> 00:48:25,666
 
is a brand-new avenue of
research.

815
00:48:25,666 --> 00:48:27,766
DUNNE:
We see a lot of fossils that we
can't quite

816
00:48:27,766 --> 00:48:31,433
figure out exactly how they fit
into the grand family tree

817
00:48:31,433 --> 00:48:33,933
of ancient life,
and so we are working with

818
00:48:33,933 --> 00:48:36,133
some very difficult fossils,

819
00:48:36,133 --> 00:48:37,600
and putting all this stuff
together

820
00:48:37,600 --> 00:48:39,766
is very, very difficult
for scientists.

821
00:48:39,766 --> 00:48:42,000
(rain falling, thunder rumbling)

822
00:48:42,000 --> 00:48:43,866
PEECOOK:
We can see that the ecosystems
were changing.

823
00:48:43,866 --> 00:48:46,066
We can see
that the climate was changing.

824
00:48:46,066 --> 00:48:47,633
But how those interact,

825
00:48:47,633 --> 00:48:49,333
what actually would have
affected the dinosaurs,

826
00:48:49,333 --> 00:48:51,733
what would have caused them
to be successful,

827
00:48:51,733 --> 00:48:53,733
we don't know yet.

828
00:48:53,733 --> 00:48:55,533
This is why there are
so many paleontologists

829
00:48:55,533 --> 00:48:57,900
doing active research.

830
00:49:00,133 --> 00:49:02,466
NARRATOR:
What scientists do know today

831
00:49:02,466 --> 00:49:05,366
is that the world
of the dinosaurs will persist

832
00:49:05,366 --> 00:49:08,933
for over 160 million years.

833
00:49:10,766 --> 00:49:15,866
♪ ♪

834
00:49:21,533 --> 00:49:23,366
Life on our planet...

835
00:49:23,366 --> 00:49:25,233
(explosion roars)

836
00:49:25,233 --> 00:49:28,566
...has been punctuated by
catastrophes.

837
00:49:28,566 --> 00:49:31,500
And although
the extinction at the end

838
00:49:31,500 --> 00:49:34,733
of the Permian might seem
like a distant nightmare,

839
00:49:34,733 --> 00:49:38,733
it holds lessons
for our own future.

840
00:49:38,733 --> 00:49:43,133
CUI:
Both the end of the Permian
and today,

841
00:49:43,133 --> 00:49:45,066
we are seeing
rising global temperatures,

842
00:49:45,066 --> 00:49:50,266
lower oxygen levels in the sea,
and ocean acidification.

843
00:49:50,266 --> 00:49:53,500
Today, there's no volcano--
it's just us.

844
00:49:54,933 --> 00:49:57,066
TIKOO:
While we're not releasing
as much greenhouse gas

845
00:49:57,066 --> 00:49:58,933
as was released during

846
00:49:58,933 --> 00:50:00,800
the entirety of
the Siberian Traps eruptions,

847
00:50:00,800 --> 00:50:04,466
the fact is, we're releasing
them a lot faster today.

848
00:50:06,133 --> 00:50:08,500
NARRATOR:
And our fast-changing
environment

849
00:50:08,500 --> 00:50:11,966
is affecting life everywhere.

850
00:50:11,966 --> 00:50:13,233
We are driving things
to extinction

851
00:50:13,233 --> 00:50:14,733
at, at an extremely rapid rate.

852
00:50:17,366 --> 00:50:18,600
SHUKLA:
If the loss of life

853
00:50:18,600 --> 00:50:20,933
continues to go unchecked,
we may very well

854
00:50:20,933 --> 00:50:25,700
be in the midst of another
mass extinction on this planet.

855
00:50:25,700 --> 00:50:28,966
NARRATOR:
But even after the worst
catastrophes

856
00:50:28,966 --> 00:50:31,900
in Earth's history,

857
00:50:31,900 --> 00:50:34,833
life recovers.

858
00:50:34,833 --> 00:50:36,900
DUNNE:
The extinction at the end
of the Permian

859
00:50:36,900 --> 00:50:39,033
both shows
us the fragility of life,

860
00:50:39,033 --> 00:50:42,100
but also shows us
how resilient life can be.

861
00:50:43,733 --> 00:50:45,633
FORMOSO:
The most amazing thing
about life

862
00:50:45,633 --> 00:50:48,666
is how it bounces back from
these devastating events.

863
00:50:48,666 --> 00:50:52,400
However,
it comes back differently.

864
00:50:52,400 --> 00:50:53,933
BENCA:
It takes a long time

865
00:50:53,933 --> 00:50:56,733
for life to rebound from
these sorts of events.

866
00:50:56,733 --> 00:51:01,033
MONARREZ:
If we continue on our
current path,

867
00:51:01,033 --> 00:51:02,500
we risk altering
life as we know it.

868
00:51:02,500 --> 00:51:06,633
We also risk our place
as humans on this planet.

869
00:51:08,000 --> 00:51:10,866
NARRATOR:
And yet hope remains.

870
00:51:12,900 --> 00:51:15,833
Human beings are
an ingenious species.

871
00:51:17,600 --> 00:51:20,333
SINGH:
We've gone from hunter-gatherers
to traveling through space.

872
00:51:20,333 --> 00:51:22,066
If we can do all that,

873
00:51:22,066 --> 00:51:24,733
I'm confident we can
sort out our current problems.

874
00:51:26,166 --> 00:51:28,800
NARRATOR:
What does the legacy
of mass extinction

875
00:51:28,800 --> 00:51:33,333
mean for our future?

876
00:51:33,333 --> 00:51:35,766
Whether it's a massive eruption
of lava

877
00:51:35,766 --> 00:51:38,866
or human beings
burning fossil fuels,

878
00:51:38,866 --> 00:51:42,433
the Earth is going to be fine--
it's the species

879
00:51:42,433 --> 00:51:44,133
that are living on the Earth
at the time

880
00:51:44,133 --> 00:51:46,200
that might not make it through.

881
00:51:48,133 --> 00:51:50,033
In the long term,
the Earth will come back

882
00:51:50,033 --> 00:51:51,966
from where we are today.

883
00:51:51,966 --> 00:51:54,400
The question is just
whether we as a species

884
00:51:54,400 --> 00:51:56,000
will be here to see it.

885
00:51:56,000 --> 00:51:59,900
♪ ♪

886
00:52:06,666 --> 00:52:07,866
NARRATOR:
On "NOVA: Ancient Earth"...

887
00:52:07,866 --> 00:52:09,166
AISHA MORRIS: One major event

888
00:52:09,166 --> 00:52:10,666
can have these ripple effects

889
00:52:10,666 --> 00:52:12,033
throughout the rest of history,

890
00:52:12,033 --> 00:52:14,300
and this event is almost
unmatched.

891
00:52:14,300 --> 00:52:17,066
STEVE BRUSATTE:
In the history of life,
it is one unfolding story--

892
00:52:17,066 --> 00:52:20,033
so many new characters coming in

893
00:52:20,033 --> 00:52:22,133
and old characters
going extinct.

894
00:52:22,133 --> 00:52:25,166
ZERAY ALEMSEGED:
What I'm holding is the earliest
child ever discovered.

895
00:52:25,166 --> 00:52:27,566
This species was at the cusp
of being human.

896
00:52:27,566 --> 00:52:31,466
NARRATOR:
"Humans" on "NOVA."

897
00:52:31,466 --> 00:52:32,966
Next time.

898
00:52:32,966 --> 00:52:34,866
SINGER:
♪ Wish I could go back in time ♪

899
00:52:46,300 --> 00:52:53,833
♪ ♪

900
00:52:57,666 --> 00:53:05,266
♪ ♪

901
00:53:06,900 --> 00:53:14,433
♪ ♪

902
00:53:16,066 --> 00:53:23,600
♪ ♪

903
00:53:29,333 --> 00:53:36,500
♪ ♪