All language subtitles for The UnXplained s08e03 Unnatural Disasters.eng

[William Shatner]
A dense forest,

leveled without explanation.

Ravenous insects on a path
of total destruction.

And a massive tremor

that may have been caused
by human hands.

Fire.

Floods. Earthquakes.

Humanity has always faced

natural disasters that often
strike without warning,

leaving death and destruction
in their wake.

But there are many other strange

and rare events that
are just as frightening

and deadly.

Like mysterious fireballs
that race through the sky,

exploding toxic lakes

and powerful tsunamis
that some believe

can summon the dead.

Are these disasters
simply freak events?

Or could they be signs
of something unnatural at work?

Well, that is what
we'll try and find out.

? ?

[Shatner reads on-screen text]

At over two million
square miles,

it's the largest forest
on Earth.

And on June 30, 1908,

this remote
and inhospitable landscape

experienced
a devastating disaster

known as the Tunguska event.

On this June morning in 1908,
a massive explosion

occurs over this
remote part of Siberia.

This became a major mystery
in world history.

At this period in time,
this area was mostly inhabited

by an Indigenous group
called the Evenki.

They had traditionally engaged
in reindeer herding,

and there were
several of them who were out

pretty close
to the epicenter of the blast.

Evenki herders see
a bright object in the sky,

described as
brighter than the Sun.

[loud booming]

And then,
they heard these loud booms,

louder than gunshots.

[Ben McGee] What the Evenki
described was nightmarish.

Suddenly, another sun
appears in the sky.

[loud booming]

You hear the loudest noise
you've ever heard

along with
a very violent shockwave.

People were blasted
off their feet

and thrown a distance.

And then,
almost as fast as it started,

this fades away, and

you're left wondering,
what happened?

[Tony McMahon]
There is an enormous explosion,

and what happens
is that something like

80 million trees are flattened

over an 800-square-mile area.

I mean, this is
absolutely bizarre,

and yet, here you have
this devastation.

[Paul Byrne]
It must've been terrifying.

Every single tree is flattened
in the same direction.

80 million of them
over 800 square miles.

We just see flattened trees

completely scorched and devoid
of any branches or leaves.

[Shatner]
What kind of explosive force

had the power to annihilate

an 800-square-mile area?

It's been estimated
this would require

the energy equivalent
of 1,000 atomic bombs.

Early 20th century theories
proposed the disaster

was the work of a massive meteor

striking
the Siberian wilderness.

[Bruno] When the Tunguska blast
occurred in 1908,

and even when it was first
investigated in the late 1920s,

the expectation was

that this must be
one of the largest

meteorite events
in modern times.

One of the early researchers
was this guy, Leonid Kulik,

who gets support from the
Soviet Academy of Sciences

to begin these expeditions.

In 1928, Leonid Kulik
expected to find

a crater
and a big chunk of metal.

But he did not find
a crater or a meteorite.

Even to this day,
we have not found

a crater that was caused
by Tunguska or even material

that can clearly be traced back
to a cosmic origin in 1908.

[Byrne] How did something
smashing into Earth

leave no crater
and flatten 80 million trees

without leaving
any other trace of it?

When an asteroid or comet
smacks into Earth's surface,

the classic thing that you get
is an impact crater.

Meteor Crater in Arizona
is a perfect example of this.

But in the Tunguska event,

we see no evidence
of a crater at all.

And so, the enigma here is,

how do you get, potentially,
something striking Earth, but

not seemingly
to strike Earth at all?

[Shatner] In the absence
of an impact crater

or verified cosmic debris,

attempts to explain
the unnatural event

have ranged from a black hole
passing through Earth

to weapons of mass destruction.

But 70 years after Tunguska,

a strange anomaly on a small
island in Newfoundland, Canada

may offer some clues
to the cause

of the mysterious
Siberian disaster.

It's known
as the Bell Island Boom.

April 2, 1978, in Newfoundland,

about 5,000 residents
of Bell Island

suddenly, spontaneously,
see an enormous flash of light,

and it's followed
by an explosion

that damages almost
every building in the town.

Gouts of blue fire erupt
from power outlets.

Livestock were killed,

and the sound of this blast
was heard 80, 90 miles away.

And initially,
they thought, well,

maybe this was a giant
meteor impact, but

there was no crater,
there was no impact debris.

So, people thought immediately
of similarities with Tunguska.

One possible explanation
for the Bell Island Boom

is what we call a superbolt.

We think that superbolts
are basically lightning bolts,

but they're far, far
more powerful than a normal one.

They release trillions of watts
of energy instantaneously.

So, that leads scientists
to wonder,

could a superbolt be responsible
for this Bell Island Boom?

[Shatner] Was an extremely rare
and powerful lightning strike

the cause of both
the Bell Island Boom

and perhaps the Tunguska event?

While it's a matter
of speculation,

many scientists believe the real
answer came even more recently,

and much closer to where
the Tunguska event took place.

[Shatner reads on-screen text]

This major industrial center

near the border
of the Siberian taiga

is one of the largest
cities in Russia.

On February 15, 2013,
at approximately 9:20 a.m.,

residents record
incredible footage

of a meteor the size of a house

rocketing through the sky.

Sometimes, an asteroid
or a comet can come in

at a very shallow angle,

parallel with the surface
of the Earth

to blow up in the atmosphere,

and it's there where you can get
something we call an airburst.

In 2013, there was
just such an airburst.

It was about 14 or 15 miles up.

It came in, heated up,
turned into a fireball

brighter than the Sun, and left

a huge cloud
through the atmosphere.

[man speaks Russian]

[McGee]
And people filed outside

to see what the bright light
was caused by.

And little did they know,
that whole time, through the air

was an invisible shock wave
carrying the sound

and the force of that blast,
half a megaton.

And boom!

Every window in the town
is shattered.

Every car alarm
goes off at the same time.

Thousands of buildings
were damaged,

thousands of people injured.

And this was a small-scale
Tunguska that we got on video.

[Byrne] We now think that
the most likely explanation

for the Tunguska event
is that an object

hit Earth's atmosphere
at extremely high velocity

and exploded, and that
energy release was enough

to flatten those trees,
scorch the ones nearby.

And rather than
excavating a crater,

it basically just
blasts out a wave of energy

that flattens trees.

And it may be that
the Chelyabinsk event

explains all
of the eyewitness testimony

of people back in 1908
reporting what they saw.

It's our best explanation
right now,

but we may never know for sure

what caused the blast in 1908.

[Shatner reads on-screen text]

This dry and arid region
encompassing Kenya,

Ethiopia, and Somalia

is famous for
its dramatic mountains

and vast savannas.

But in 2019,
it became ground zero

for a locust swarm
of unimaginable proportions.

[Jeffrey Lockwood] The most
famed or infamous locust

is the desert locust of Africa.

Where they land,
it's utter devastation.

They are descending
in order to feed,

and you can watch your fields
disappear before your eyes.

So, to understand locust swarm,

you have to kind of
go back a few,

a few months or a few years.

The parents of these locusts

would've appeared
as garden-variety grasshoppers.

But then, the conditions change.

It becomes drier,
and they undergo

a Dr. Jekyll to Mr. Hyde
transmogrification.

And instead of their offspring
looking like their parents,

they're like mobs of small,
wingless, uh, locusts

that march across the land just
eating whatever they encounter.

And then,
after about three weeks,

they molt into adults,
winged adults.

And they rise
into the sky, and they

appear to be kind of
a glittering storm cloud

on the horizon.

And if you're a farmer,
you watch

your crops melt in front of you

so it looks like a wildfire
has swept through.

Nothing is gonna stop them
until they're done.

They leave nothing behind
except misery and hunger.

[Shatner] The East African
locust swarm of 2019

destroyed an estimated $8.5
billion dollars' worth of crops,

resulting in a food crisis

affecting nearly
25 million people.

But history's most devastating
and mysterious swarm of locusts

assembled nearly 150 years
before the African disaster.

This time, in the United States.

[Shatner reads on-screen text]

From the Rocky Mountains
to the Mississippi River,

American farmers
struggle to survive.

Years of harsh
weather conditions and drought

creates hard, dry
prairie soil difficult to farm.

But even more devastating
is the freakish mega swarm of

Rocky Mountain locusts
that have assembled

on a biblical scale.

[McGee] This wasn't just
any locust swarm.

There were more than 12 trillion
locusts that made a swath

that was a thousand miles long,

and basically, you can think of

a swarm the size of California

munching its way
across the American Midwest.

And these locusts
were so ravenous,

they not only
absolutely annihilated

all the crops
in the American Midwest,

the locusts began eating

anything else they could find
that was organic.

That includes
the wool off of live sheep,

it includes wood
structural elements of houses,

and it includes clothing
that people were wearing.

And so, this was terrifying.

These things were alive
and they were hungry.

[Lockwood]
This mega swarm of 1875

is the largest recorded swarm
in human history.

It was 2,000 times larger than
the next largest known swarm

of locusts on planet Earth.

Something that summer coalesced
them into this mega swarm.

It was a natural disaster
of unimaginable scale.

500 to a thousand tons
of vegetation

have to be consumed every day
to fuel that swarm.

Much of the Midwest
was gonna face hunger.

People are gonna die.

But we don't really know very
much about what led up to it.

[Shatner]
Over the course of three years,

the ravenous insects devoured
$116 billion dollars' worth

of crops and property,

leading to widespread starvation

and complete financial ruin
for countless families.

And based on this unfathomable
devastation, many wondered

was this mysterious disaster
a grim judgement

from the Almighty?

[McMahon] If you read
the newspapers from the time,

it really conveys the terror

that these farming
communities felt

as these locusts completely
destroyed their livelihoods.

And of course,
many of these God-fearing people

looked to the Bible
and thought, "Well,

Pharaoh in Egypt
was punished with locusts.

Surely, we're being punished
for our sinfulness.

We have done something wrong

and we are now facing
divine retribution."

That's what many people thought.

[Lockwood]
Governors in five western states

declared days of prayer.

And then, you say, "Well,

God helps those
who help themselves."

What do you do in the
industrial age to fight nature?

Build a machine. Right?

Machinery must be the answer.

All kinds of machines are built.

One was called
the King Suction Machine.

A belt-driven, gigantic vacuum
that would suck up

the nymphs- these are
the wingless immatures-

and bag them.

[horse neighs]

You might try various rolling
devices to crush these locusts.

One of my favorites
was, basically,

a flamethrower
to torch the locusts.

Not very effective, but it
probably felt pretty good.

Now, did it make a dent
in the locusts, probably not,

but it did give the people
a sense of being in control.

[Shatner] While we still don't
know what caused the largest,

most destructive
locust swarm in history,

what's even more perplexing

is that, by the year 1902,
just 27 years later,

the Rocky Mountain locust
completely vanished

from the face of the Earth.

[McGee] It was only
a couple of decades after

this titanic storm

of locusts
that the Rocky Mountain locusts

went extinct,
disappeared forever.

You talk about
a dynamic contrast.

It went from effectively
swallowing the country...

...to vanishing without a trace.

And why?

Well, perhaps
it was loss of habitat

and human civilization's advance
just meant the conditions

weren't favorable
for them anymore.

We don't really know.

[Lockwood]
Another theory was

they didn't go anywhere,
they're still here.

And it just so happens
that the right conditions

have not happened again

that would transform
an existing grasshopper

into the Rocky Mountain locust.

We still can't explain
what caused the rise

of the Rocky Mountain
locust swarm

and ultimately
what caused their demise.

And it may forever
remain a mystery.

? ?

It's baffling to think
that trillions of locusts,

swarming over an area more than
a thousand miles wide,

could suddenly vanish
into extinction.

[clicks tongue]

But that's not
the only mystery of nature

that continues to defy
scientific understanding.

For example,
there's a lake in Cameroon

that may be part of a network
of toxic, ticking time bombs.

[Shatner reads on-screen text]

The Sun rises
over the hills surrounding

an ancient body of water
known as Lake Nyos

and reveals
an apocalyptic scene.

In nearby villages,
lifeless bodies are strewn about

as if a mysterious force
had swept across the land

killing nearly everything
in its path.

There was a terrifying

geological catastrophe
that occurred.

Something disrupted this lake.

Locals reported a rumbling sound
and what might be described

as an explosion as the lake
suddenly came to life.

And anyone who was caught
in its path

instantly dropped dead.

[Shatner]
The death toll was staggering.

It's estimated around
1,700 people and 3,500 animals

were killed
across a 14-mile radius.

With no obvious cause of death,

an international team
of scientists-

including American
biologist George Kling-

was dispatched to investigate.

We really didn't know what had
happened, what had caused this.

And the lake itself was

very reddish-orange,

like a rust color

that we really don't see
very often in lakes.

And there was a lot of damage
around the shoreline

from some large wave

that must have been produced
with enough force

to wash away all the vegetation
and soil down to bare rock.

And lakes just
don't explode like that.

[Shatner]
What exploded out of Lake Nyos

killing everything in its path?

Given that the lake was formed
in an ancient volcanic crater,

investigators feared
that an eruption,

deep underground,
released a surge of deadly gas.

[Kling] Many of the survivors
reported smelling rotten eggs

or gunpowder, and that's
an unmistakable smell of sulfur,

and they reported feeling warm.

And we know volcanoes produce
a lot of sulfur gas

and a lot of heat.

But when we started
analyzing our samples,

we found no sulfur
in the lake water.

We found no excess sulfur
in the plants

around the lake that had been
exposed to this gas cloud.

And when the army pathologists
did autopsies,

they found no evidence

that people were poisoned
by sulfur gas.

[Shatner]
No poisoning by sulfur gas?

Experts were left wondering

if the cause
of this deadly disaster

was even geological at all.

Local rumors swirled
about chemical spills,

weapon tests,

even stories about
vengeful spirits in the lake.

But George Kling
found something intriguing

buried in old medical reports.

A clue pointing to
a rather unlikely culprit,

a gas that we all produce
when we exhale,

carbon dioxide,
otherwise known as CO2.

[Kling] We ran across
some older medical literature

that had used
high concentrations of CO2

to test for oxygen stress
in fighter pilots.

And it turns out that CO2

above concentrations
of about six percent

acts as a sensory hallucinogen.

And one of the most common
reports from the fighter pilots

was that they smelled
rotten eggs and gunpowder

and that they felt very warm.

So, we knew that
this was a CO2 release,

and we suspected that the gas
was held in the lake.

It turns out that
the lake itself

could hold a huge amount
of gas in the bottom waters.

[Shatner]
Kling's tests reveal

that Lake Nyos
was primed for disaster.

Over centuries, the lake
had become a pressurized

chamber of carbon dioxide.

And when that chamber exploded,

it released a massive wave
of suffocating gas

that raced across the land
at over 60 miles per hour.

Lake Nyos, as it turns out,

was supercharged
in carbon dioxide,

much like a soda can

if you shook it up
before you opened it.

So, anyone unfortunate
to be caught in its path

couldn't breathe.

[Kling] One of the things
that made this event so deadly

was that this CO2 gas cloud
was enormous, first off,

but because
it was heavier than air,

it flowed out of the lake
and down the river valleys

very quickly,
so even if people had seen

the cloud coming, they couldn't
have gotten out of the way.

And people just
essentially died in place.

Lake Nyos was vulnerable
to this kind of an event because

it was formed
by volcanic activity,

and it's also very deep.

So, those deep waters
could store a lot of gas.

But once we have the gas build
up, we have to have a trigger,

and this could be
any number of things.

For example,
it could be a landslide

that caused the gas burst,

but we'll probably
never know for sure

what triggered this disaster.

[Shatner]
Based on Kling's discovery,

Lake Nyos is now monitored
around the clock

to help anticipate
another deadly gas event.

But solving
the Lake Nyos disaster reveals

a far more terrifying question.

With more lakes
potentially primed

for the same kind
of catastrophe,

when and where
could this happen again?

Lake Kivu in East Africa is the
nasty big brother of Lake Nyos.

It's 1,600 times larger.

It has a thousand times
more gas in it.

And because there are
millions of people

living around
the shoreline of that lake,

it's the largest
ticking time bomb in the world.

There are active volcanoes
in the area.

And these volcanoes
could destabilize it

and trigger a gas burst.

We haven't looked at
every single lake in the world,

but we know now
enough about what

kinds of lakes
could be dangerous.

[McGee]
Knowing that this is a process

that the Earth can throw at us,

it's natural to wonder,
are other lakes susceptible?

The good news is
it doesn't happen everywhere.

But the bad news is, if there's
one that we don't know about,

we need to find it first
before it lets us know

it's there
in all the worst ways.

How many lakes around the world
are filled with poisonous gases

that could explode
at any minute?

While there's
much left to learn,

there are some disasters

that aren't triggered
by natural processes

that take millions of years
to unleash.

Like in the case
of a catastrophic earthquake

that may have been the result

of human engineering.

[Shatner] Throughout history,
Mother Nature has revealed

that the ground beneath our feet

is far less stable
than we like to imagine.

In the last century alone,

cities have been suddenly
reduced to rubble.

And nearly two million people
around the world

have been killed
by the unbelievable ruin

caused by earthquakes.

[Klose] Earthquakes we can
observe around the world.

Wherever you are
on any continent,

you have plenty
of fault zones everywhere.

Large fault zones
will cause large earthquakes,

and an earthquake happens
if you build up stress

over thousands
and millions of years,

and those fault zones can
basically rupture at some point.

[Shatner]
While scientists can't predict

when an earthquake will strike,

we generally assume
that they're caused

by natural processes that take
an extraordinarily long time.

But could some of the deadliest
earthquakes of the modern age

be caused by human hands?

[Shatner reads on-screen text]

This region is home
to over 80 million people,

making it one of the most
populous places in all of China.

But just before 2:30
in the afternoon,

a massive earthquake unleashes

unspeakable death
and destruction.

[Shatner] The deadly earthquake
struck along

a 155-mile fault line

running the base
of the Longmen Mountains.

But when scientists pinpointed
the quake's epicenter,

they found something massive
and man-made.

The question is,
what triggered that earthquake?

Although we know
that this region

is a natural seismic region

where we have earthquakes
every other hundreds of years,

seismologists
are able to measure

how waves propagate
through the Earth's crust.

And that's what they did.

They looked at the seismic wave
they recorded

and they could see that,
in the first ten to 15 seconds,

most of the energy was released

right in the vicinity
of the Zipingpu Dam.

[Shatner] The Zipingpu Dam
stands over 500 feet tall,

and its reservoir holds

more than 296 billion
gallons of water,

weighing more than
one trillion tons.

Scientists began to wonder,

did this monumental
engineering project somehow

trigger the earthquake

that killed
an estimated 87,000 people?

When it comes to the idea
of humans

artificially triggering
earthquakes to occur,

if you do something to add
a lot of weight to an area-

like create a dam
and then generate a new lake-

well, the weight
of all of that water

can induce
any number of changes.

And in some areas,
definitely activate earthquakes.

That's what led us to suggest

that the pressure
can be that large

and that could weaken the fault
and trigger the earthquake.

[Shatner] While it seems
the Zipingpu reservoir

could have a role in
the deadly Sichuan earthquake,

the theory remains controversial

and is not acknowledged
by the Chinese government.

But it all raises
a chilling question.

What other massive man-made
structures could potentially

bring about
an unnatural disaster?

[Byrne] Closer to home,
the Hoover Dam is among

the largest reservoirs
in the world.

[explosions]

And in fact, even during
its construction in the 1930s,

there were quakes nearby
because there are structures

in the ground
that are going to move.

The big question becomes this,
if those structures move again,

are we going to have
an issue with this dam?

There's no doubt that

whether it's caused
by man or Mother Nature,

those impacted
by a disaster are left

haunted by the event itself

and the aftermath that follows.

But when the tsunami of 2011

destroyed parts of Japan,
some locals were affected

on an otherworldly level,

when the living
were reportedly visited

by the dead.

[Shatner reads on-screen text]

A massive
9.1 magnitude earthquake

strikes dangerously close
to the Japanese mainland.

This seismic event
displaces so much water,

it sends hundred-foot waves

barreling towards
Japan's eastern shore

at 500 miles per hour,

in an event known as the
Tohoku earthquake and tsunami.

[Parry] The earthquake set off
a massive tsunami,

which struck
the coastline of Eastern Japan,

and that is what caused
devastating damage.

It's like the tide coming in

unstoppably, massively,
and very, very, very fast.

The tsunami smashed
into villages, towns, ports

all along the coast.

It caused a meltdown

at the Fukushima Daiichi
nuclear power station,

which turned into
the second worst

nuclear disaster in history.

The devastation is overwhelming.

Imagine turning all houses,
factories sideways,

spreading out
all the chemicals and debris,

destroying roads.

You have flows that are filled,
not just with mud and trees,

but cars, and building
fragments and rooftops.

And this is spread
all the way inland, many miles,

and then dragged
back out to sea.

There were more than
19,000 people killed

in this event, and it becomes

the deadliest event in Japan's
history since World War II.

[Shatner] The entire region
grappled with enormous loss

and unimaginable trauma.

And some who managed
to escape death

would also experience
disturbing events

of an otherworldly kind.

Because in the months
after the tragedy,

tsunami survivors
started to report

ghostly encounters
with the dead.

[Parry] Six months or so
after the tsunami,

among many people
who survived it,

you did begin to hear

various stories about

supernatural mysterious events.

There were stories about

mysterious figures glimpsed
by the coast on the beach.

And then, there were

also the stories told
by-by taxi drivers.

A taxi driver is flagged down
by a lonely figure

who got in the back of the taxi

and gave him an address.

And he gets there

and, sure enough,
there is nothing there.

All the houses have been
smashed to pieces by the wave.

He looks in the back
of the taxi-

the person isn't there.

And he understands that

the passenger was a ghost
who wanted to go back

to the place where
they'd formerly lived.

There was something ghostly

happening along
that stricken coast.

[Shatner] Did thousands
of sudden deaths unleash

the spirits of those
that perished in the tsunami?

It's an unnerving question

because there were also
reports that these spirits

possessed the living.

[speaking Japanese]

[translated]
I perform purification rituals,

but also exorcism, if you will.

Living people
were possessed by spirits.

After the tsunami,
everyone around there

had almost no physical
or mental immunity left.

So, they were
in a state where spirits

could easily attach themselves.

So, our method of exorcism

involved guiding them
into a meditative state

and then expelling it
with a big breath.

Strangely enough,
with one woman,

smoke suddenly puffed out of her
mouth and the spirit left her.

And when she
came back to normal,

she was like, "Why am I here?

Did something happen to me?"

[Shatner]
While the actual number

of claimed spirit possessions
is unknown,

mediums, folk healers,
and holy men

became inundated
with desperate calls for help.

[speaking Japanese]

[translated]
I was in the thick of it,

facing people
suffering from possession

and doing whatever I could.

They're in a daze. Their face
is blank. They're limp.

It feels like
their personality has changed.

We performed rites to calm them.

You need the power of ritual
and the power of deep listening.

I engaged with them and
released them from possession,

and brought them back
to daily life.

But facing possession
takes so much out of you,

to the point
you feel you might die.

[Shatner] Did tsunami ghosts
roam Japan's devastated coast

and possess those that survived?

While some are convinced
that this was a real

supernatural phenomenon,

others suggest
a less esoteric explanation.

After a terrible
disaster like this,

I think there are two impulses
that people have.

One is naturally to feel

horror about what has happened,

and I think
these stories of ghosts,

the sense of the supernatural
bearing in on all sides,

is an aspect of that,
of that fear and that horror.

But there was
another side to it.

There's a strong,
strong yearning

to connect with the dead.

To say the goodbyes,
the farewells

that weren't possible
in this sudden catastrophe.

But to the people
having the experiences,

they were very, very real,

and they needed
to be taken seriously.

[Shatner] Natural disasters
have always threatened humanity.

Some believe the danger's
only growing.

Between the year 2000 and 2019,

there were over 7,000
major recorded disaster events

around the world,

nearly twice as many
than the previous two decades.

And scientists warn
that the next major disaster

could come from immense forces

buried beneath
the Earth's crust.

[loud booming]

[Byrne]
One source of catastrophic

environmental change we know
happened in Earth history

are gigantic volcanic eruptions.

If we look through
the geological record,

we see thousands
of these events.

Like we saw in Siberia
about 250 million years ago

leading to the biggest mass
extinction in Earth history.

98% of all species
on Earth went extinct.

The atmosphere was rendered
almost unbreathable

because of how much CO2
came out.

We know that these kinds
of events have happened

through Earth history.

In fact, geologically,
they happen regularly,

and we do not have the ability

to predict if or when
the next one will happen.

There are catastrophic eruptions
that volcanoes are capable of,

and Yellowstone
is a great example.

Yellowstone Caldera is
a huge depression in the ground

with an enormous body
of magma at depth.

Now, right now, that magma
seems to be relatively stable,

but we know that there were
gigantic volcanic eruptions

in the past, and it may yet
explode in the future.

[Shatner] Could a massive
volcanic eruption

unleash Earth's next
mass extinction event?

It has happened before.

But there are other apocalyptic
forces not born of this Earth,

like the same cosmic threat

believed to have killed
the dinosaurs.

A lot of extinctions in our past
were actually caused by comets.

If you were to look
at our solar system,

the whole solar system
is surrounded

by a giant sphere of old junk.

Think of it as icy spare parts

from when the solar system
was first built.

This is where
all comets come from.

And one hypothesis is that,

as our solar system moves
through the galaxy- bam.

A slew of comets are fired in
toward the inner solar system,

and so it really does
make you wonder

whether future mass extinctions

have to do with our
galactic neighborhood.

[Shatner]
Will a series of comets

soon bombard Earth
like artillery shells?

The fact is, we can't accurately
predict future disasters at all.

And mankind lives and dies

at the mercy of forces
that are beyond our control.

[Byrne]
At some point in the future,

it won't be a question
of if, but when

Earth decides to clean house.

But every time
these disasters happen,

the environment bounces back.

Now, I hope we won't learn this
on our own lifetimes,

but it will surely
happen again at some point.

One question we should ask is,
have we figured out all the ways

in which these disasters
might happen?

[Kling] Most of us understand
that being prepared

doesn't always help us when
we're exposed to the unknown.

We have to accumulate
more facts,

more information.

Sometimes, people assume that

scientists have it all
figured out,

that they have seen everything.

They pretty much understand
what's happening.

But these disasters
have really shown us

that we had no idea
about major events

that have happened in the past

and may happen
in the future as well.

Is Earth overdue
for an unspeakable disaster

on a scale we've
never witnessed before?

Well, I sure hope not.

And whether
a massive volcano erupts,

a giant space rock
collides with Earth,

or any number of terrible
cataclysms are on the horizon,

it's clear that deadly
catastrophes are inevitable

as long as we call
this planet our home.

While Mother Nature has taught
us to respect the elements,

it's the unpredictable

and unnatural disasters
that leave us humbled

by forces that remain
unexplained.

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