(theatrical music)
Narrator: Earth is born out of chaos and catastrophe.
(planets explode)
Despite such hostile conditions,
life emerges on our planet.
But it must withstand deadly disasters again and again.
Planet Earth is a wild world
shaken by unimaginable impacts,
volcanic eruptions that flood the landscape,
and drastic climate changes that lead to ice ages
that freeze the world from pole to pole.
Yet, each assault creates a path for something new.
Life always finds a way
despite being constantly put to the test.
Without these catastrophes,
life as we know it would not exist
on our "Fateful Planet".
(theatrical music)
66 million years ago when an asteroid impacted Earth,
75% of all species became extinct,
including all the non-avian dinosaurs.
The tenacious life that re-emerged in the Cenozoic
would ultimately lead to humankind today.
But violent Earth forces and extreme climate changes
continue to threaten our path forward.
So scientists must investigate the past
to prevent our extinction in the future.
And while we have survived thus far,
more dire calamities loom on the horizon
that may again threaten all life as we know it,
including us.
(wind blowing)
Morocco.
Just two hours west of Marrakesh,
archeologists have uncovered the oldest remains
of homo sapiens, modern humans.
Professor Abdeljalil Bouzouggar from the National Institute
of Archeological Sciences and Heritage in Morocco
hopes that the ancient bones will reveal new information
about the development of humankind.
-: The extinction of the non-avian dinosaurs
66 million years ago paved the way
to the development of other mammals.
This leads to the development of hominids,
including homo sapiens.
Narrator: Humankind has had a long evolutionary journey.
Fossil records combined with DNA studies
reveal the last common ancestor
of both humans and chimpanzees
live between five and 6 million years ago.
After that, the species diverged.
The hominids developed an upright posture.
This was a critical point in human evolution
because it freed our hands to handle objects.
An upright posture is shared by all hominid species
that would appear throughout Earth's history.
Today, only one remains: homo sapiens.
To learn more about our early ancestors,
Abdeljalil meets with Professor Abdelouahed Ben-Ncer
at the excavation site of Jebel Irhoud.
The professor discovered remnants
of an ancient human shelter
that also yields groundbreaking information
about human evolution.
This is an exact replica of a skull
found here by Ben-Ncer.
It has rewritten the beginning of our human history.
-: It's exciting, I'm holding out
the oldest example of the homo sapiens in the world,
because the date is around 315,000 years ago.
We thought that homo sapiens existed in Africa
around 200,000 years ago.
With this new discovery in Jebel Irhoud,
the scientists pushed back the age
of more than 100,000 years ago.
(light music)
Narrator: Ben-Ncer also found sophisticated tools
and weapons from the Middle Paleolithic
between 250,000 and 25,000 years ago.
They represent a significant step in human evolution,
proof of the growing intelligence
that sets us apart from all other animals on Earth.
-: In this place, there are a lot of fireplaces,
and fire were used for many reasons.
One of them was to cook the meat.
That means that we will increase the protein in this food,
which was really very necessary and helpful for the body,
but especially for the brain,
which was really something,
a huge step in the human evolution
in this part of the world.
Narrator: A larger, more organized brain
was key to the next stages of our evolution.
A day's drive from Jebel Irhoud,
Professor Bouzouggar has found more evidence
of increasingly refined evolution
in our early ancestors.
(cinematic music)
Grotte Des Pigeons is a cave that was discovered
by scientists over a century ago.
-: This is a treasured trove.
It's helping us to better understand homo sapiens,
not only from a biological perspective,
but also from a social and cultural perspective.
Hi Miriam.
How are you?
-: I'm good, thank you.
Narrator: Professor Bouzouggar works
with PhD student Miriam Benagati
to record any archeological finds in the cave.
Miriam: Looks like there's something unusual here.
(light music)
-: Can you see?
Miriam: Yeah. -: It's perforated.
That's a shell bead.
The most interesting and fascinating things we found
are shell beads.
These snails, they are marines
and they came from the coast.
So those people around 82,000 years ago,
they went to the sea to collect these species,
which means that it is really a long distance walking
in order to collect such snails.
Narrator: The closest coastal spot today
is about 30 miles from the Grotte Des Pigeons.
Bouzouggar is certain this is where our ancestors
must have collected the shells.
-: Here in the beach,
you would have seen thousands of shells,
but our ancestors collected only tiny shells.
'Cause they are only three centimeters,
so they can't be brought to the cave
to be consumed by these people.
You have to get thousands of these tiny shells
to even get half a kilo of the shells.
So it can't have been
a food source.
So the question is,
why did our ancestors
bring them to the cave?
Narrator: When the scientists examined the shell beads,
they realized stone or bone tools
had been used to perforate them.
-: This is the first time when homo sapiens
will use something which is not a tool,
but something which probably was decorating their bodies
or probably their clothes.
Narrator: This crafting of shell beads
mark significant progress in our evolution.
-: To make such things like shell beads,
you need to be able to talk,
to explain to other members of the group
that in one or two days walking from the cave,
there is a coast where these shells are available.
Narrator: Our ancestors didn't just travel to the coast.
They would migrate out of Africa
in search of new food sources,
and their journey would take them to the site
of a deadly catastrophe.
It was an event that had potential to cause
the demise of humankind.
A world away from Morocco,
Antarctica holds surprising clues
about a calamity our ancestors had to face.
Ice can store vital details about our planet's history
over millions of years.
In the 1990s, scientists discovered something astonishing
in ice cores dating back to 74,000 years ago,
extremely high levels of sulfur.
The presence of sulfur was the first indication
that something catastrophic might have happened
and the magnitude of the deposits revealed
that it was possibly cataclysmic.
An event of this magnitude
had the potential to wipe out our early ancestors,
and perhaps all life on Earth.
Scientists scoured the planet for the possible origin
of such a massive eruption.
Their search finally drew them
to one of the few features on Earth
capable of producing such an event:
the Pacific Ring of Fire.
It's a vast chain of volcanoes that stretches
more than 25,000 miles
from the southern tip of South America
along the west coast of North America,
across the Bering Strait and down into Japan
and New Zealand.
The Ring of Fire boasts 75%
of all active volcanoes on Earth.
They form a horseshoe-like shape
around the edge of the Pacific Ocean
due to the movement of tectonic plates.
This is a geologically active region,
where the Pacific Plate slides beneath
the surrounding continental plates
in a process called subduction.
(tense music)
When the heavy Pacific Plate sinks below
the lighter continental plates,
pressure turns the dense mantle
of the Pacific Plate into magma
and pushes it towards Earth's surface.
Over millions of years,
this has created the chain of volcanoes.
Sumatra.
Indonesia is a country within the Ring of Fire.
It has some of the highest rates
of volcanic activity on the planet.
So, geologist Dr. Martin Danisik has come here
to search for clues about what may have happened
74,000 years ago.
His investigation begins at Mount Sinabung,
where a deposit near the active volcano
has caught his attention.
(rock cracks)
-: I'm using a hand lens to actually check
what kind of composition we have in this particular rock.
I can see it's very pores.
I can see different minerals here.
This rock is called ignimbrite.
Narrator: Ignimbrite is a volcanic rock
that forms during explosive eruptions.
The large size of this deposit
indicates it was produced by a massive event.
But although further analysis reveals
that the eruption occurred 74,000 years ago,
the geologist is doubtful it can be tied
to the sulfur-heavy cores found in Antarctica.
Danisik believes this volcano is not the culprit.
-: Sinabung Volcano is simply too small.
It's not capable to produce this size of pyroclastic flow.
And what that means is that
there must be a gigantic volcano
that produced these rocks.
(tense music)
Narrator: Danisik's search for possible sources
of the eruption leads him to one
of Sumatra's biggest landmarks.
-: This is Lake Toba.
It's enormous.
It goes a hundred kilometers this way.
It's about 30 kilometers wide.
Narrator: Lake Toba is so vast
it contains an island the size of Singapore at its center.
The island itself is also peculiar,
with sheer cliffs rising unusually high
above Lake Toba surface.
(light music)
-: This is Samosir Island.
It's highest point is over 1600 meters.
Now, we are at 900 meters.
This can give you an idea of how high
the island rises above this lake.
Narrator: Dr. Danisik is able to access
the island's sub-surface at a local quarry.
And an outcrop reveals a surprising layer of sediment.
-: It's actually sediments that form in lake.
Now, we are probably 400 meters
above the current lake level.
So the lake can be seen over here,
but these sediments formed below water,
if that makes sense.
(tense music)
Narrator: The scientist sees
only one explanation for this.
-: The answer is that Samosir Island
is a huge block that used to be below water,
and then it was pushed up, was uplifted
by a leftover magma in a magma chamber.
Essentially we're standing in the middle of a giant volcano.
(tense music)
Narrator: The extinct volcano is so large
it's difficult to even recognize it from the ground,
and Lake Toba is the caldera.
-: And approximately 74,000 years ago,
this volcano produced a gigantic eruption.
We call it super eruption.
(tense music)
Narrator: Toba exploded in a cataclysmic eruption
that released gas, ash, and magma
on an unprecedented scale.
The super volcano shot more than a thousand cubic miles
of volcanic matter into the sky.
The billowing clouds heated
to over 1,000 degrees Fahrenheit,
spelled death for any vegetation in their path.
When the plume collapsed,
it sent more than 8 trillion tons of volcanic material
hurdling towards the ground at over 250 miles an hour.
(intense music)
(thunder claps)
A lethal pyroclastic flow devastated everything in its path.
(pyroclastic flow swooshes)
-: Probably everything within a radius of 100 kilometers
was obliterated by pyroclastic flows.
Narrator: Volcanic debris spread across
the Indian Ocean and into Asia,
covering several million square miles
of the planet's surface.
But, long-term consequences of the mega eruption
would be even deadlier than the immediate aftermath.
Sulfur dioxide emitted from the volcano
formed a veil around the globe,
blocking out sunlight.
Some scientists believe Earth's temperature
dropped by up to 16 degrees Fahrenheit
-: On a global scale, it's been proposed
that this super eruption could have caused
a bottleneck in human population.
Meaning, that the number of individuals
living on this planet would reduce
to 3,000 to 10,000 individuals.
Narrator: If true, humankind came close to extinction
74,000 years ago,
and the theory assumes Africa and Asia
sheltered the few survivors.
(light music)
Back in Morocco, Professor Bouzouggar has been investigating
how our ancestors reacted to the super eruption.
He isn't convinced of the bottleneck theory.
-: We didn't only found 82,000 years old shell beads,
but we found others which are much younger,
like this one which is dated to around 70,000 years ago.
This means that the Toba eruption
didn't act as a bottleneck for homo sapiens.
'Cause here what we can see is an evolution
of homo sapiens without disruption.
Narrator: While the Toba eruption
may not have endangered humankind survival,
Earth still pose challenges for homo sapiens.
Evidence of an environmental shift
can be found within the cave.
Our ancestors apparently needed to keep warm.
-: This edge was probably used in order to cut,
you know, branches of the trees.
And this is something very new.
This is a new technology in this context.
And this shift could be related to a climate change.
Narrator: To understand how the environment changed,
Professor Bouzouggar and his student
search for hidden clues.
The researchers want to understand how eruptions
can affect the environment,
because during the millennia that followed
the Toba super eruption,
Earth posed new challenges for homo sapiens.
-: When analyzing these charcoals,
we understand that in this part of the world, in Africa,
the climate was dry.
And if we compare it with Europe during the Ice Age,
it's slightly different.
Narrator: The climate had changed
due to the shifting of Earth's position to the sun.
In the North, glaciers grew.
50,000 years after the Toba eruption,
they reached their maximum.
Our early ancestors forged their way
through the frozen wilderness of an Ice Age.
Sharing the challenges with colossal creatures,
somehow humans adapted and thrived.
This Ice Age boasted a surprising array of megafauna.
Majestic mammoths roamed the plains
and saber-toothed cats proud for prey.
Humans co-existed with these magnificent animals.
Pleistocene cave art reveals the art ancestors had
for these creatures
as they immortalized their encounters on the stone walls.
As the Ice Age drew to a close,
the changing climate altered habitats
and transformed landscapes.
Soon, the balance between humans and animals
also began to shift.
-: During the Ice Age,
homo sapiens was hunting megafauna for meat
and to use their hides for shelters or for warms.
And scientists now know that homo sapiens
was sufficiently reproducing,
and by having the size of the population growing,
they were in need of more resources, food resources.
Narrator: The human population was growing,
resources were dwindling,
and competition for them with us
may have caused the numbers of megafauna to decrease.
The huge animals began to disappear.
People hunted the once abundant Ice Age herds,
and the animals weren't able to reproduce quickly enough.
-: Homo sapiens group survived
because they have a long history,
and they were adopting also some kind of hunting strategies
which helped them to survived.
Narrator: The megafauna numbers rapidly declined
over about 2,000 years.
Most of the majestic creatures vanished,
never to roam the landscape again.
-: Around 10,000 years ago, ice melted,
which means that homo sapiens grew.
They need a new to adapt a new behavior,
and this behavior will lead
to what we now know about storing
and also about domesticating plants and other animals.
(light music)
Narrator: Crop cultivation and the keeping of livestock
provided our ancestors with a stable
and reliable food supply.
This radical shift from a nomadic, hunter-gatherer lifestyle
to an agrarian one would define the Neolithic Revolution.
-: And when you have this kind of activity,
you need private property.
When you got this, you need to build cities.
And then you need to defend these cities.
Narrator: Settlements grew into towns and then cities.
Trade became vital as civilizations were created.
This was the beginning of the modern world,
and it happened quickly.
(light music)
We have reshaped our planet
and even traveled beyond it.
But regardless of humankind's ingenuity,
Earth's primal forces remain beyond our control.
(light music)
Hebgen Lake, Montana.
We are a success as a species and we continue to progress.
But on our planet and in the cosmos,
unexpected threats to our survival still loom.
These bare trees are silent witnesses
to a catastrophe that unfolded here
during the summer of 1959.
Seismologist Dr. Jamie Farrell is investigating an event
that was triggered by the ceaseless reshaping of Earth.
-: On the night of August 17th,
there was an earthquake, magnitude 7.3,
that shook the entire region.
Unfortunately, there were some people in the Madison Canyon,
downstream from Hebgen Lake at a campground,
and just above them, the mountain gave way
due to the shaking.
And there was a huge landslide, rock slide that came down
on the campground.
(suspenseful music)
Reporter: One of America's worst series of earthquakes
in this century felt throughout the Northwest
centers its forests on Southwestern Montana.
In Madison River Canyon, 50 million tons of earth and rock,
the top of an 8,000-foot mountain
thundered across a forest campground
in one of the biggest landslides.
-: So many people were buried underneath that landslide
that are still there today.
(morose music)
Narrator: The event is tragic proof of the immense amount
of seismic activity that occurs in this region.
Around 2,000 earthquakes occur here every year.
Many are never even felt.
-: So right here where we're standing now,
we're now at the actual fault scarp here
from the Hebgen Lake earthquake in 1959.
And what you see here is
you see this big break in the earth here,
and prior to the earthquake,
these two levels would've been on the same level.
And instantaneously, as soon as the earthquake happened,
this side here mostly just dropped down along the fault.
So, six meters of offset,
(fingers snaps) like that.
Narrator: But something must have triggered
this fatal landslide.
Jamie's research leads him to a huge
and famous potential threat nearby.
Yellowstone, the first national park in the world.
Continuous hydrothermal activity beneath the park surface
creates a natural spectacle,
but it also hides a potentially lethal catastrophe
much larger than the Toba eruption.
-: So here we're looking at Grand Prismatic Spring.
This is one of the iconic hot springs
in Yellowstone National Park.
It's one of the largest hot springs in the world,
and this is one of many
of the thermal features here we have in Yellowstone.
We have over 10,000 thermal features here in the park.
Narrator: The incredible attractions
draw millions of visitors every year.
But while they're stunning,
the hydrothermal vents and pools
can quickly become dangerous.
Geologic activity in Yellowstone must be closely monitored.
One of Jamie's roles is to probe the source
of the hydrothermal springs and geysers.
-: So my job as a seismologist is to monitor Yellowstone
for seismic activity.
We have about 40 seismometers running
in Yellowstone all the time.
So this is a map of all the earthquakes
that have been located in the Yellowstone region
from the '70s to the present.
And what you can see here, the green outline here,
this is Yellowstone National Park.
Each one of these dots represents one earthquake.
There's over 50,000 earthquakes on this map
that we've located from the '70s to now.
(light music)
Narrator: The seismometers record
even the faintest ground movement.
-: So we can use data recorded on these instruments
to find out that, you know,
about five kilometers beneath our feet in Yellowstone,
there's a magma reservoir.
There's molten material beneath us
that's feeding all the things that we see in Yellowstone.
The thermal features, the earthquakes,
the ground deformation,
that's what's the source of all that,
all that change that we can see.
Narrator: Yellowstone's intricate network of hot springs
is fueled by magma stored below Earth's surface.
The magma is also responsible for pressure changes
that lead to the region's numerous earthquakes.
Three miles below the landscape,
the molten rock lies in a chamber
nearly 55 miles long and 25 miles wide.
It is the source for one
of the largest volcanoes in the world,
a super volcano like Toba.
-: We're standing right now on the north rim
of the Yellowstone Caldera.
And down there to our south, about 40 kilometers
where you can see those snow covered mountains,
that's the southern edge of the caldera.
So this is a good perspective
of just how massive this caldera is.
And this is the reason why, you know,
a lot of people don't realize,
they're asking where the volcano is,
but they've been in it most of the time.
Narrator: This giant chamber holds
a huge amount of magma.
-: So with the scale you can see here,
the magma is about the same size as the caldera
that you can see behind me right here.
And the amount of material that's down in there
is kind of mind-boggling.
There's enough material down there
that if you took all of it,
you could fill the Grand Canyon about 10 or 11 times.
Narrator: But where does all the magma come from?
While Toba and many other volcanoes were formed
from subduction at the boundary of tectonic plates,
Yellowstone is different.
This volcano was unusual
because it formed in the middle of a plate.
Underneath the plate lies an anomalous hotspot,
much warmer than the surrounding mantle.
Plumes of magma from the hotspot rise towards the surface
to feed the reservoir beneath Yellowstone.
Scientists need to know if the Yellowstone super volcano
poses a threat today.
Humankind survive the aftermath
of a super explosion in the past,
but what about in the future?
Volcanologist Dr. Madison Myers
is investigating Yellowstone's past
to learn more about the destructive power
this volcano might be capable of.
(light music)
-: A volcanologist job essentially is to look at rocks,
try to understand what happened in the past,
and then try to figure out what could happen in the future.
Narrator: Yellowstone's rocks reveal
that the volcano erupted multiple times
over millions of years.
Most eruptions were minor,
but two were devastating.
-: So by studying the deposits around Yellowstone,
we're able to tell that there was actually
two, large, super eruptions that occurred here.
The oldest at 2.1 million years ago
is the Huckleberry Ridge Tuff,
wrapped around 2,500 cubic kilometers,
and then the younger one, at 630,000 years ago,
is the Lava Creek Tuff,
which formed the Yellowstone Caldera,
which we can see here.
We're actually sitting on the caldera edge right now.
Narrator: Nearly 250 cubic miles of material
was ejected by Yellowstone's most recent eruption.
Ignimbrites, ash, and quartz crystals
are still found throughout the area.
These remnants of the enormous event
show that it dwarfed the most violent catastrophes
in modern history.
-: Well, if you think of Mount St. Helens,
Mount St. Helens was this enormous,
extremely impactful volcano.
And you can imagine just the plume going up,
the devastation that happened in the forest,
that was one cubic kilometer, right?
So if you have the ability to expand that
by multiplying it by a thousand,
that's what the Lava Creek Tuff eruption was like.
(suspenseful music)
Narrator: The landscape was in upheaval
because of this eruption,
and eventually the entire region collapsed.
Now, researchers wonder if a similar explosion
could happen again.
(intense music)
-: There's no reason to think that it couldn't happen again.
We do have like a chain of essentially volcanic centers
leading up to this that have shown
that multiple, large eruptions have happened.
So it is very feasible that in the future
you might have a super eruption.
(light music)
Narrator: To potentially forecast
how much warning time we'd have
before a catastrophic eruption.
Dr. Myers examines the ancient volcanic deposits for clues.
-: So with the rocks that we take back to the lab,
we're able to look into them and kind of dissect
what their histories were.
So we use different instrumentation to try to image it,
try to get a picture of what was happening.
Narrator: She is focused on tiny crystals
within the rocks, which are snapshots
from the last major eruption.
They record details,
much like the rings inside a tree trunk.
-: So, in trees, you see these different zones
that are representing growth of the tree's life.
The same thing's true for crystals.
They record the different kind of phases of their life.
And so by looking at these different zones,
we can see, oh, this eruption actually was triggered.
Narrator: Based on her research,
Madison is certain that geologists will be able to predict
an impending super eruption, well, in advance.
-: Volcanic systems often have warning signs,
and the more you monitor them
the more warning signs they often give.
And Yellowstone is one of the best monitored volcanoes
in the United States.
So it's gonna give off plenty of warning signs,
likely for the same kind of decades
to century long time skills that the crystals are recording,
'cause the crystals are recording changes
in pulses of magma coming in.
That's an earthquake, right?
So we would have signals that we could use
to understand that unrest was happening.
(suspenseful music)
Narrator: Seismologist Jamie Farrell
is also on the lookout for these signs.
-: The main things that we would look for,
the main things that we monitor for here in Yellowstone
are increased seismic activity,
increased ground deformation,
and then changes in the gas output in Yellowstone.
So we would look for those three things.
If one of those things changes,
that doesn't necessarily mean anything's outta the ordinary.
But if all three things happen at the same time
and they're all pointing to the same thing,
then we would know, okay, maybe magma's moving up
into the shallow crest.
It might make it to the surface.
Let's look at this deeper.
(intense music)
Narrator: The scientists know
that if a super eruption does occur,
it would have catastrophic consequences.
-: Yeah, another super eruption
would change our world completely.
I mean, it would have at least decades of impact.
-: One thing we would definitely have,
we'll have a big explosion.
You know, it would eject a lot of material, a lot of ash.
We would have a lot of asphalt in the surrounding areas.
We've had of pyroclastic flows coming out from the plume,
devastating the area around here in the park.
Narrator: The effects of such an eruption
would reach far beyond North America.
-: These large volume eruptions
are gonna have devastating consequences.
They shoot these huge plumes way up into the stratosphere
that likely cycle the world multiple times,
leading to this global winter
where vegetation's going to struggle,
animals will struggle,
and so it would be a completely devastating
and life altering event.
I would say that it's probably one of the top things
that could threaten humankind.
Narrator: It would be a global catastrophe,
far greater than the Toba eruption,
that would endanger all life on Earth once again.
(theatrical music)
But life on our planet isn't just threatened by disasters
created by Earth's processes.
In 2013, residents of Chelyabinsk, Russia
witnessed a dramatic event.
The sky blazed as an asteroid entered Earth's atmosphere.
Caught on dash cams and surveillance videos,
people were stunned.
(light music)
Frascati, Italy.
The European Space Agency is one of the few organizations
dedicated to monitoring space hazards.
Dr. Richard Moissl, head of Planetary Defense,
has been studying the Chelyabinsk event in detail.
-: We know that the impactor had about
a diameter of 20 meters.
The asteroid approached with an estimated velocity
of over 66,000 kilometers a second.
The damage went into the millions.
Unfortunately, many people got hurt.
In total, there were more than 1,400 people injured.
But we can consider this even a lucky event
because the energy deposited in the atmosphere
was several times that of the Hiroshima bomb.
(light music)
Narrator: Things could have been much worse.
With a diameter of 65 feet,
this asteroid is tiny compared to those
that impacted Earth in the past.
66 million years ago, an asteroid with a diameter
of around six miles struck Earth.
Instantly, the energy of billions of nuclear weapons.
was released when the impactor vaporized,
melting the bedrock into molten plasma.
The resulting thermal radiation, earthquakes, and tsunamis
wreaked havoc around the globe
on an unprecedented scale
and was one of the most disastrous events
in Earth's history.
The impact caused a chain reaction of horrific events
that caused the extinction of 75% of all species
alive at the time.
(asteroid explodes)
(dinosaur roaring)
(air swooshes)
Asteroids remain among the biggest threats to our planet.
-: There's a lot of stuff out there.
Today, we know more than a million asteroids already
which are out there.
But of these, 30,000 are especially interesting
because they come close to Earth.
That's what we call the near-Earth objects,
and these are the ones of particular interest to us.
We track them as much as we can,
but we don't only determine their orbits
where they are at the moment.
We determine their paths up to 100 years into the future
and check if they actually will become
a danger to us one day.
Narrator: Fortunately, most of these asteroids
are only a few inches to a few yards in diameter.
Every day, more than 100 tons
of harmless debris and dust from space
bombard our planet.
(asteroid whooshes)
-: They usually burn up in the atmosphere as shooting stars,
creating a spectacle, nothing more.
But once in a while, asteroids come along
which are bigger in size and do pose a danger.
Narrator: This is what happened in Tunguska,
a remote forested region of Siberia.
A monster explosion caused one
of the most devastating impacts in human history.
On the morning of June 30th 1908,
a massive event shook the landscape.
Brilliant lights illuminated the sky
and were seen as far away as the UK.
The first scientific expedition
to examine the resulting damage
didn't occur until 1927.
Footage taken at the location
shows widespread destruction.
Over 80 million trees were flattened
and a 1,250 square mile area of forest was destroyed.
But despite the devastation,
there was no sign of an impact crater
and scientists could not determine
where the asteroid struck.
-: So there has been no conclusive answer
to what caused the Tunguska event to date.
But the most probable explanation still remains to date
an impact of a very porous body with low density
that caused an airburst of the magnitude
that we observe here.
(asteroid swooshes)
Narrator: When an asteroid enters Earth's atmosphere,
it creates an airburst.
Because the impactor travels at high velocity,
pressure builds in front of it
until the asteroid bounces off its target or breaks apart.
When this happens, energy is released
in a huge burst of light and heat,
(asteroid explodes)
which causes immense destruction on the ground surface.
-: Luckily, this event didn't cause any confirmed casualties.
But it would be completely different story
if something like this were to happen
over a density populated area or a big city.
Narrator: At the European Space Agency,
the Planetary Defense Team regularly simulates
emergency scenarios so they will be prepared
if an asteroid threat becomes a reality.
Richard: We've taken the data
from the Tunguska simulations
and projected them right over Manhattan.
The software now shows us the impact effects
at the location.
(intense music)
Narrator: A Tunguska-sized asteroid
about 160 feet wide
would demolish the metropolis
even after it broke apart 20 miles above Earth.
(intense music)
(asteroid explodes)
-: The blast wave would shatter all windows,
would damage all buildings not built
out of reinforced concrete to a considerable degree.
(asteroids exploding)
Many people would die
and millions would be affected and injured.
Narrator: The blazing heat would destroy
block after block, affecting most of New York City.
An asteroid strike like this
would be a tremendous catastrophe for humankind.
(intense music)
-: These things are the reason why
we have developed early warning systems
so that we can notify the authorities ahead of time,
so that in turn they can step in
and evacuate the affected areas,
thereby saving up to millions of lives.
Narrator: Once an asteroid is spotted,
it is ranked and added to the asteroid risk list.
The more Richard and his team can learn
about the asteroid's potential path,
the better they can determine if it will strike our planet.
But is there anything that can be done
if a dangerous asteroid is heading straight for Earth?
(tense orchestral music)
In 2021, the European Space Agency teamed with NASA
to launch what became known as the DART mission,
or the Double Asteroid Redirection Test.
The goal was to prevent asteroids
that might pose imminent threats from hitting Earth.
The DART probe mission planned to rendezvous
with a double system
consisting of the asteroid Didymos
and its moon, Dimorphos.
This was the first attempt in space exploration
to change the course of an astronomical body.
The plan was to send a probe
that would deliberately collide with the asteroid.
-: During its final approach,
DART transmitted a live stream of images
while it was homing in on the double asteroid system.
This is footage that has never seen it the likes before.
And we first see how DART is closing in
on the double asteroid system.
Then passing by the primary, the big one,
zooming in ever closer on the small one, on Dimorphos.
Finally, the small one fitting the field of view
until, bam, DART hits the asteroid,
and the transmission ends.
Narrator: The test was successful.
But would the technology be sufficient to save us?
-: The course of the asteroid was indeed changed
for the first time in human history.
At first, it would only move by a fraction of a millimeter.
But in time, if an asteroid is hit early enough
when it still has billions of kilometers to go
to reach its target Earth,
a tiny distance can grow in time
to be thousands of kilometers,
turning a potential impact of a killer asteroid
into a harmless flyby.
(light music)
Narrator: Emergency strategies developed
by the Planetary Defense Team,
combined with ever advancing technology,
could potentially divert a rogue asteroid
to prevent the extinction of humankind.
But, even if we can avert threats from space
and from within the Earth itself,
humans pose a growing menace to our own survival.
Rhone Glacier, Switzerland.
The Swiss Alps are a relic from the last glacial period.
As the head of the Swiss Glacial Monitoring Network,
Dr. Matthias Huss
from the Swiss Federal Institute of Technology in Zurich
regularly checks on the conditions of the glacier.
-: This glacier, like all glaciers in the Alps and worldwide,
has receded considerably.
12 years ago, it extended all the way
to the end of the lake here,
which didn't exist at the time.
Now, the glacier has retreated.
Its thickness has decreased dramatically.
Narrator: Dr. Huss is worried about
the extent of the changes.
So, he has set up a monitoring system
to record the rate of the glacial melt.
(light music)
-: We have had so-called glacial selfie sticks
on this glacier for several years now.
They take a picture of the glacier every hour,
which allows us to see how much it melts from day to day.
The stick is firmly embedded in the ice.
As the ice melts and the camera sits on the surface,
it looks as if the stick is growing out of the ice.
Narrator: High resolution cameras
capture the rate at which the ice is receding.
-: The glacier surface decreases a lot throughout the year.
We lose around 20 to 26 feet of ice annually in this area.
Narrator: The Rhone Glacier is only one glacier
that is melting.
At the current rate, around two-thirds
of the continent's current glacial cover
will be lost by the end of the century.
Natural variation in ice volume is to be expected.
Since the beginning of the last Ice Age,
this glacier has grown and shrunk,
normal for such an immense body of ice.
But, what we are seeing now is different.
-: The warming we had until a few hundred years ago
was natural due to solar radiation and other factors.
But what we are witnessing now is manmade climate change.
Narrator: Human actions, like burning fossil fuels,
industrialization, deforestation,
and intensive agriculture, have all created
a tremendous increase in greenhouse gases.
The massive amount of CO2 we relentlessly pump
into the atmosphere is warming our planet
at an alarming rate.
Global temperatures are estimated to rise
by nearly five degrees Fahrenheit
by the end of this century.
-: Glaciers are primary indicators of climate change.
They clearly demonstrate the consequences
of rising temperatures as ice melts with warmer weather.
Everyone understands that.
You don't have to be a scientist to realize that.
Narrator: The changes seen here are impressive.
Within a single generation, the alpine landscape
has completely changed.
-: Globally, the melting of this glacier in the Alps
may seem insignificant.
However, if all glaciers worldwide
along with the large polar ice caps melt,
sea levels will rise.
This poses one of the greatest long-term threats
to life on Earth and to the way we currently live.
Narrator: Since industrialization began,
global warming has caused sea levels to rise
by nearly eight inches.
By the end of this century,
they could rise over three feet.
Mega cities like Jakarta, Indonesia
could be swallowed by the sea.
Coastal settlements would be lost
and even further inland, the severe effects would be felt.
-: We're talking about heavy rainfall, floods.
We're talking about droughts and heat waves
that will become much more frequent in the future.
All of this renders regions uninhabitable.
We will witness climate refugees,
and perhaps wars over water in the future
as a result of very, very significant consequences,
far reaching consequences
that humanity must somehow get control of.
Narrator: Global warming will cause natural disasters
like hurricanes, floods, and droughts to increase.
Fresh water is becoming increasingly scarce,
and famine is on the rise.
Forest migration and unrest leading to wars could result.
Between 3.3 and 3.6 billion people on Earth
are extremely vulnerable to the negative consequences
brought about by climate change.
-: The problem lies primarily in the extreme velocity
at which we can now observe manmade climate change.
We are transitioning from one dimension
to a completely different one
within a generation or two.
Adapting to this is incredibly difficult
and represents the greatest challenge
humanity will be facing in the coming decades.
Narrator: Yet, Dr. Huss remains optimistic.
While humans are the cause of this problem,
we also have the tools to create the solution,
if we act soon.
-: We actually have a choice now.
We still have it in our hands to set the direction
in which our planet is moving
and whether it will remain habitable in the future.
We still have a few decades to make this course correction,
and I hope that we can achieve this as a global community.
Narrator: Earth now has more than 8 billion people,
and collectively, our existence has caused the demise
of many other species.
The current rate of extinction is higher
than any of those seen during the last five,
major mass extinctions.
If Earth continues to grow warmer,
this rate will accelerate.
Some scientists believe that we are already experiencing
a sixth mass extinction,
and it is one that might eventually include humankind.
But as Earth stewards, we can learn from the past
while using technology now and in the future
to protect our planetary home
for ourselves and other species.
The future of life on our fateful planet
now rests in our hands.
It's up to us whether we are a part of it.
(cinematic music)
(water splashing)
(theatrical music)
(theatrical music continues)