Speaker 1: Since the Earth was formed billions of years ago, it's
been hit by a series of disasters. Two hundred and
fifty million years ago, the largest volcanic eruptions the planet
has ever seen nearly erased all life on Earth. It
was the greatest mass extinction in the history of the planet.
But without it, humans could never have evolved. This is
the story of the Planet of Fire. Over the last
four and a half billion years, life on Earth has
lurched from one terrible disaster to the next. It's difficult
to grasp the immense timescale of the events that shaped us,
so imagine Earth's history compressed into the twenty four hours
of a single day at ten forty in the evening.
That's two hundred and fifty million years ago, all life
on the planet faced extinction. The Earth was in a
period of prehistory called the Permian, A cataclysmic event kick
started a deadly chain reaction that wiped out nearly all
animal and plant species on the planet. It was called
the end Permian extinction and was the greatest die off
in the history of the planet. Ninety five percent of
all creatures around the globe were wiped out. According to
South African paleontologist Roger Smith, it was earth darkest hour.
Speaker 2: The income extinction was as dramatic as a mass extinction
could be. Since the beginning of life on Earth, there
has been no other one that has come close to
the ninety five percent of species on Earth, both in
land and sea, disappearing within a very short space of time.
Speaker 1: It was a catastrophic wipebout and changed the course of evolution.
We humans are only here today because of the five
percent of creatures who survived.
Speaker 2: Had it not been for those few survivors, those few
animals which were preadapted or able to get through that
great drought, we would not have had life on Earth.
Speaker 1: What happened? How did it happen? It's a mystery that's
puzzled scientist since evidence of the catastrophe was first discovered
almost half a century ago. Figuring out what cause the
extinction is a key element to understanding the evolution of
life on Earth. In the Karoo basin, South Africa, Smith
studies an area that was once teeming with animals that
predate the dinosaurs.
Speaker 2: But two hundred and fifty million years ago, this would
have looked a very different place. Rainfall in the mountain
areas were feeding Mississippi sized rivers, which meandered themselves slowly
across the plains. This was a fully developed, stable ecosystem.
Speaker 1: Small plant eating creatures called Dictodon thrived here, scurrying around
in the vegetation. Huge herds of calcized herbivores called dicynodonts
grazed on the plains, but a vicious killer stalked the herds.
Over one hundred and fifty million years before, t Rex
Gorgonopsian was Earth's deadliest carnivore. Armed with serrated, interlocking teeth,
this ferocious animal was the ancient world's top predator. But
all these creatures were doomed. None of them survived the
mass extinction. What killed them clues to how the Permian
world died. Lie buried in the rocks of South Africa's
Karu Basin. Under this scrub, Paleontologists have unearthed layers of
sedimentary rock from this turbulent time.
Speaker 3: Now.
Speaker 2: Sedimentary rocks like this are characterized by layers, each layer
representing a point in time when deposition was taking place.
The oldest layers are at the bottom and the youngest
layers at the top.
Speaker 1: These rocks are like a time machine, taking us back
a quarter of a billion years one layer higher up.
This formation offers clues to what ended the Permian world.
Speaker 2: Here we're sitting at the very top of the Permian
and this particular interval shows us something very dramatic in
the rock record. Below me we have green and bluish
gray rocks that pretty suggests that the environment was wet.
Speaker 1: These rocks are littered with fossils. But just above this layer,
it's a very different story.
Speaker 2: Suddenly everything turns red, and that's reddening is an indication
of drying, rapid drying and warming.
Speaker 1: These red rocks reveal a sudden and dramatic rise in
temperature and mark the point in time when life on
Earth nearly died.
Speaker 2: The fossils tell us at this point there is virtually
nothing left on Earth, and we go into a dead zone.
Speaker 1: Life had almost ceased to exist. And not just here.
The dead zone of red rock is found all around
the world. This meant that two hundred fifty million years ago,
the climate change in mass extinction was global. Something huge
on a planet wide scale pushed temperatures up by twenty
degrees fahrenheit and killed virtually all life on Earth ten
forty pm on our clock of the Earth's history. Two
hundred and fifty million years ago, the planet was in
climate free fall. Scientists have discovered the temperatures rose by
about twenty degrees. The sudden and dramatic global warming changed
the course of evolution on Earth. It caused a mass
extinction so devastating that some scientists thought it must have
been caused by something extraordinary, something extraterrestrial. Could it have
been an asteroid strike? They knew a cosmic impact would
have sent billions of tons of dust high into the atmosphere,
blocking out the sun, stopping plant growth, reducing temperatures, and
causing the food chain to collapse. An extinction from an
asteroid strike would have happened within decades, but that's not
the story the rock evidence is telling us. Over the
last decade, Professor Paul Wignall and researchers at Leeds University
in England have been examining rocks from the dead Zone
around the time of the devastating mass extinction. They've collected
thousands of samples and taken hours of video on their
expeditions to Greenland. The rocks confirm a period of climate change,
and much more. They record the story of mass extinction
on land and sea and provide a clearer picture of
the die off than ever.
Speaker 4: The extinction is like the biggest fossil crime scene of
all time, and so the great thing about Greenland is
that we have such a great record at the crime scene.
If you're like, there's just a huge amount of information
to be collected. So it provides us with an extremely
detailed record of what happened, probably one of the best
records of that time interval.
Speaker 1: What's more, these Greenland rocks build a solid case against
the asteroid impact theory.
Speaker 4: One of the most obvious clues would be that the
extinction should go extremely fast, within sort of days and
weeks of an impact, everything will just sassis drop dead
in a matter of years, and so that should be
raise a sharp when we see in a fossil record,
we should see just an abrupt line or termination, and
that's not what we see.
Speaker 1: Instead, Wignoll's rock showed that the extinction happened over a
period of one hundred thousand years, far too long to
be the result of a meteor strike. The Greenland's team's
discovery meant that something else must have caused the catastrophic extinction,
and geologist Mike Benton thinks he knows what. He believes
the disaster began deep beneath the Earth's surface.
Speaker 5: If it is not impact, then the next most obvious
dramatic instant kind of catastrophe is initiated by volcanic eruptions
of some kind, so you obviously look for some center
of volcanic eruptions.
Speaker 1: Volcanoes are nature's ultimate destructive force. Fueled by unimaginable pressure
deep within the planet, they shoot molten rock and toxic
gases high into our atmosphere. In nineteen seventy five, the
eruption of Mount Tobochik in Russia was so huge the
plume of ash and debris was visible from space. But
geologists know that volcanic eruptions were far bigger and more
powerful two hundred and fifty million years ago, because they
found the aftermath in eastern Russia. Today. Deep beneath the
frozen wastes of one of the most remote corners of
the Siberia is evidence of the catastrophe that nearly killed
off life. A vast expanse of ancient lava flows forming
a bleique landscape called the Siberian Traps.
Speaker 4: The Siberian Traps are a style of volcanism which we
don't see today. They represented the biggest style of vulcanism
that the Earth ever experiences or produces.
Speaker 1: Earth's ancient volcanic eruptions dwarf anything we might witness today.
At the end of the Permian period, millions of cubic
miles of magma built up beneath the Siberian crust. The
entire region began to bulge upwards, and then like a
giant blister, the Earth erupted, spewing out vast amounts of lava,
flooding the area under a sea of molten rock. It
was a type of volcanic eruption called a flood basalt.
Here was the force behind the mass extinction two hundred
and fifty million years ago. The Siberian flood basalt released
enough lava to cover an area of the size of
the United States under one mile of molten rock. Siberia
has long since cooled, but Iceland is still one of
the world's most geologically active places. Here, Mike Benton researches
the terrible impact even a small flood basalt could have had.
Speaker 5: We're here in the middle of a lava field in
Lachee in Iceland, because this is a very well documented
historical basalt eruption that can act as a good analogy
for the Siberian traps. In seventeen eighty three, a vent
eruption happened here which lasted for about eight months.
Speaker 1: Seventeen mile long volcanic vents shot fountains of lava four
thousand feet into the air, but it was tiny compared
to the Siberian eruptions. Even so, it was a disaster.
Speaker 5: Volcanoes produce three things. The lava is one that will
kill things locally, but it produces ash and most importantly gas.
Now the lava goes a relatively short distance, the ash
will go further flying through the air. But what really
kills are the gases.
Speaker 1: The Larky eruption produced huge quantities of sulfur dioxide. It's
a gas which has a deadly impact on the environment.
When it mixes with water vapor in the atmosphere, it
turns into sulfuric acid and falls to Earth as acid rain.
Speaker 5: That has a terrible effect, as was recorded by the
people at Lucky, where they reported that it burned people's eyeballs.
It made it hard for them to breathe because it
congested their lungs. Livestock suffered lesions and burning of their skin,
and plants were killed off.
Speaker 1: The whole food chain began to collapse, and that was
just the start. Some sulfuric acid didn't fall back to
earf It stayed in the atmosphere in small droplets. Question
These reflected sunlight away from the planet, cooling its surface.
Speaker 5: The cooling following the Lucky eruption was catastrophic. It killed
more people than the immediate damage by sulfuric acid. It
created very cold winters for two or three years after
the eruption, not just on Iceland, but throughout much of
northern Europe. People reported crop failures and death as a result.
Speaker 1: Benton's analysis of the Larky eruption has shown that the
cooling effect produced by volcanic sulfur dioxide is deadly and
that the effects can be felt thousands of miles away.
Imagine how devastating the Siberian traps must have been. Larkie
spewed out gas and lava for eight months and covered
an area of about two hundred square miles in molten rock.
The Siberian traps erupted for nearly half a million years.
They produced about two million square miles of lava that's
two hundred thousand times larger than Larkie. Using Larkie as
a model, Benton can begin to reconstruct the chain of
events that turned the Siberian eruptions into a global killer.
Speaker 5: The most likely sequence of events starts with these massive
eruptions in Siberia, with lava spreading over thousands of square
kilometers square miles of landscape and causing destruction and devastation
wherever they went.
Speaker 1: The eruptions released billions of tons of sulfur dioxide into
Earth's atmosphere, which created acid rain and volcanic winters and
scent global temperatures plummeting around the world. The climate change
killed plants, and the food chain fell apart. The plants failed,
herbivores like dicynodonts, starved, and where they starved, the carnivores
that ate them died too. Ten per cent of species perished.
But this was just the beginning. Another gas released by
the Siberian traps was about to make things much much worse.
Ten forty PM on Earth's evolutionary clock. Two hundred fifty
million years ago, a series of giant volcanic eruptions have
plunged the planet into chaos. The sulfur dioxide released by
the Siberian traps has devastated animal and plant populations. In England,
paleontologist Paul Wignall conducts post mortems on the victims of
the Permian extinction, and these fossils he collected in Greenland
definitely felt the effects of volcanic gases.
Speaker 4: The first things that start suffering in the entire fossil
record is the plant record. We start seeing a change
in the composition of plants, and also we start to
see the appearance of some very strange mutated sports.
Speaker 1: The fossilized plants reveal a world struggling to adapt to
climate change. They also record the effects of a second
deadly volcanic gas, carbon dioxide.
Speaker 4: Looking at the surfaces of leaves and the number of
little holes that are in the sources of leaves is
actually monitor of how much common dioxide there is.
Speaker 1: Plants need carbon dioxide to create energy. They breathe it
in through tiny holes on the back of their leaves.
The more carbon dioxide in the atmosphere, the fewer holes
the plant needs to absorb it. When scientists studied fossilized
leaves dating back two hundred and fifty million years, they
discovered a sudden, dramatic reduction in the number of breathing holes.
It seemed that at the start of the extinction, levels
of carbon dioxide surged, and that meant one thing. The
Siberian trap eruptions must have released billions of tons of
CO two. This greenhouse gas changed global cooling into global warming.
Scientists calculate that the amount of carbon dioe oxide in
Earth's atmosphere at the time of the eruptions was twenty
times higher than it is today, more than enough to
seriously affect the climate. It was global warming gone mad.
Speaker 5: The result of these Siberian Trap eruptions was a rise
in global temperature of at least five degrees centigrade, and
they happened episodically, so that it may be there were
pulses repeated and repeated off temperature rise.
Speaker 1: A rise of five degrees centigrade that's about ten degrees
fahrenheit may sound small to us, but it had a
massive impact on the Earth's climate. Warming Earth's atmosphere affects
how rain is generated and where it falls. By raising
Earth's temperature, volcanic CO two altered global weather systems in
equatorial regions, it simply stopped raining. In South Africa, the
Karou Basin felt the full impact of this change in climate.
Its lush floodplains became a scorched desert. Paleontologist Roger Smith
studies how this rapidly changing landscape impacted the Careu's inhabitants,
and he's just discovered one of the victims.
Speaker 2: Here we have an instituted skull of Dasyanodon. It's one
of the last of the big calcized herbivores of the
Permian period, and at this level, which is just below
the extinction, this represents probably the last gasp of the
Permian herbivores.
Speaker 1: The global warming marked and evolutionary watershed in Earth's history.
Animals and plants suffered drought and starvation. Thirty five percent
of them perished, But the fallout from the Siberian Traps
was only just beginning. The rise in global temperatures triggered
a domino effect and unleashed the next terrible phase of extinction.
This time in the oceans ten forty pm on the
Earth's clock. Two hundred and fifty million years ago, massive
volcanic eruptions first released sulfur dioxide that cooled the planet,
then carbon dioxide that heated it up. The sea sawing
climate killed animals and plants. By the millions, Extinction ruled
the land. It was the first terrible phase of the
extermination of virtually all life on Earth, but a critical
moment in the story of man's evolution. The future of
life hung by a thread, but not everywhere. So far,
the oceans had escaped unscathed.
Speaker 5: The oceans at the end of the permie were teeming
with life. There were quite complex reefs made up of
corals and various other kinds of creatures that were fixed
to the seabed. Those rich life there were sharks swimming
in the shallows. The water would have been pale blue,
like any typical tropical sea, so at a distance that
it would have looked like a modern coral reef.
Speaker 1: Perhaps climate change was about to end this. Paleontologist Paul
Wignall has found evidence of the next deadly phase of
the mass extinction, the death of the oceans.
Speaker 4: This is a really nice example of blocks that we
get from Greenland. The evidence is first of all, of
a black which is typical when you have no oxygen around.
But even more telltale is these these lovely sort of
golden crystals which we can see on the surface, and
this is pyrite or fool's gold, and we'd only find
this if there was no oxygen around on the seafloor.
Speaker 1: It's an important breakthrough. Fool's gold can only form in
an environment that lacks oxygen. Its discovery in two hundred
and fifty million year old rocks means only one thing.
Somehow the Earth's oceans had lost their oxygen.
Speaker 4: It was clear that there was something major going on
which hadn't been discovered before. What we could see was
it was sudden lack of oxygen at the end Permian
mass extinction, as a completely new extinction phenomenon. It is
then that we realized that we were now looking at
a very different way of killing life in the seas.
Speaker 1: But lower oxygen levels alone can't explain why so many
species died in the oceans. It's a mystery that research
at Green Lakes National Park in Upstate New York has
helped to solve. Marine geologist Lee Cump has discovered the
process that he thinks was responsible for the extermination of
nearly all marine life two hundred and fifty million years ago.
Speaker 3: We're here at Green Lake because as we view this
as a microcosm of the ocean that may have existed
at the end of the Permian at the time of
this great mass extinction. It's a really unique habitat here
that's unusual in terms of most lakes. It's like a
typical lake at the surface, but lurking down below is
this poisonous water.
Speaker 1: The lake looks normal, but under the surface it's dying,
just like the ancient Permian oceans. The water is stagnating,
its oxygen levels dropping. Over the past five years, comp
and divers from Penn State University have been monitoring the
lake's slow death. At the bottom, they found strange colonies
of purple sulfur bacteria, an organism that only lives in
water rich in a highly toxic gas called hydrogen sulfide.
Hydrogen sulfide is a waste product produced by bacteria which
thrive in water which has no oxygen.
Speaker 3: Once the auction level drops then to the point where
there's no oxygen left. Then organisms that can't stand oxygen
being to thrive, and these organisms have a waste product,
hydrogen sulfide that is poisonous to air breathing life.
Speaker 1: Hydrogen sulfide is a vital ingredient in the formation of
Fool's gold. The large amounts of Fool's gold discovered in
the two hundred and fifty million year old Greenland rocks
suggest that the same process that's happening in this lake
was happening in the Permian oceans. Cump and his team
research the rising levels of hydrogen sulfide in the lake.
They do this by measuring the growth of purple sulfur
bacteria recording the changing depth at which it can be found.
They know they found it when they pull out pink water.
Speaker 3: We're looking for the pink water because that's indicative of
where these purple sulfur bacteria live. So this is our
marker of where these organisms have a very large population density.
There are so many there that they create this pink water.
Speaker 1: Below this toxic layer of pink water, oxygen breathing animals
cannot survive. Cump is charted the changing depths at which
pink water can be found in Green Lake.
Speaker 3: Oh yeah, that's rotten eggs. That's nasty stuff.
Speaker 1: He's discovered that does oxygen levels in the lake drop,
the amount of poisonous hydrogen sulfide increases, and the pink
water can be found closer to the surface. It means
that the poison is rising up through the water, killing
all of the oxygen breathing animals who live there. The
Green Lakes are just a small expanse of water, but
imagine it on a global scale.
Speaker 3: If we were to take a satellite picture of the
Permian Ocean, the regions that are green today would have
been pink when viewed from space because of the abundance
of the purple sulfur bacteria.
Speaker 1: Comes Green Lakes research gives us an insight into what
was happening in the world's oceans at the time of
the mass extinction. Rocks from the same period tell us
that it was a global phenomenon. Oceans and seas were
starved of oxygen and saturated with poison. Something major must
have happened to trigger the removal of oxygen, But what
In the Green Lakes. It's caused by stagnating water. The
water has stopped circulating and Recently, researchers have discovered that
two hundred and fifty million years ago, the same thing
happened on a global scale. Normally, oxygen dissolves into seawater
at the surface. It's then transported by currents circulating between
the equator and the poles. Sunlight at the equator warms
the sea water. As this warm water moves towards the poles,
it cools and sinks, carrying its dissolved oxygen down with it,
allowing the oceans and its inhabitants to breathe. This same
process was happening two hundred and fifty million years ago,
but then the Siberian Traps came along and raised Earth's
temperature by about ten degrees.
Speaker 4: A significance of that for the world as a whole,
and particularly the oceans, is the way it affects circulation
in the world's oceans. It's a bit like leaving a
goldfish bowl in the window in bright sunshine. The water
there it warms up, it loses its oxygen, and it
essentially stagnates. And so if you magify that to an
oceanic scale, then that's effectually what we think is happening
in the oceans. At the end of the pomium.
Speaker 1: The evidence suggests that two hundred and fifty million years ago,
the rapid global warming created by volcanic gases warmed not
only the atmosphere, it also warmed the oceans. They stopped
circulating oxygen and stagnated, becoming breeding grounds for poisonous hydrogen
sulfide producing bacteria.
Speaker 3: We think that the warming then led to the development
of the build up of hydrogen sulfide and the deep ocean.
This built up to such large concentrations that it invaded
into the shallow part of the ocean and displaced all
of the air breathing organisms from those environments and eventually
provided them no place of shelter.
Speaker 1: Climate change triggered by the Siberian traps had already killed
around a third of all species on land. By raising
the temperature of Earth's oceans, it then caused the death
of virtually all life in the sea. But the killing
wasn't finished. Lurking at the bottom of the oceans was
another killer, one that would wipe out practically everything else
on Earth. Two hundred and fifty million years ago, the
Siberian trap eruptions rocked the Earth and covered an area
of the size of the United States in thick molten rock.
They set in motion a chain of events that would
wipe out virtually every species on Earth. Volcanic sulfur dioxide
created acid rain and sudden winters. Next, carbon dioxide raised
the planet's temperatures so high the food chain collapsed. Then
the oceans warmed and the oxygen levels dropped. As a result,
bacteria filled the water with lethal hydrogen sulfur, turning the
planet seas into one big kill zone. Together, they cut
global animal and plant populations by a staggering seventy percent
in just fifty thousand years. Now, the animal and plant
species that managed to survive suffered a final blow. In Iceland.
Geologist Mike ben is searching for clues to this final
deadly wave of extinctions.
Speaker 5: There is a mystery to understand how the production of
condoxide and a sudden rise in global temperature of about
five degrees could have caused such a catastrophic event. A
sudden rise in global temperature of about five degrees wouldn't
in itself kill life in the catastrophic way we see.
Something else must have caused that massive scale of extinction
that we know happened that time.
Speaker 1: The gases released from the Siberian traps triggered global warming
that wiped out species, first on the land, then in
the oceans. But then temperatures increased again by another ten degrees,
the result a catastrophic second wave of extinction on the land.
Scientists know that carbon dioxide released by the traps caused
the first leap in global temperatures, but the second jump
remained a puzzle. They needed to find something even stronger
than CO two that could accelerate global warming on an
unprecedented scale, and they found the answer to this mystery
hidden in the depths of the ocean off the coast
of Santa Barbara, California, About a mile off shore. Doctor
Ira Leefer, a climatologist from the University of California, is
on his way to monitor an unusual phenomenon. He's looking
for another greenhouse gas, not carbon dioxide, but methane.
Speaker 6: This area is where methane from deep within the Earth
rises through the Earth's crust until it reaches the seabed
and then through the water column to reach the sea
surface as bubbles.
Speaker 1: You can find these bubble seeps in coastal areas all
over the planet. But this one's proximity to southern California
has given scientists a unique opportunity to monitor one closely.
Diving deep into the cold Pacific waters, Lifer's students collect
methane samples straight from a vent in the seafloor. The
sample showed that when it comes to global warming, methane
is a supergas.
Speaker 6: Methane is a very potent greenhouse gas, perhaps twenty to
twenty five times more potent on a molecule per molecule
basis than CO two. That means, if we add one
molecule of CO two to the atmosphere one molecule of methane,
that methane has twenty five times the effect.
Speaker 1: The amount of methane released by seeps like this one
in Santa Barbara is too small to explain the additional
ten degree temperature rise recorded towards the end of the
mass extinction. But there's another source of the gas that might.
In the deep ocean, the most unexplored and least understood
part of our world, there are vast quantities of a
substance called methane hydrate. It's methane gas frozen in the
cold water at the bottom of the sea. Today, there's
an estimated thirty trillion tons of methane locked away in
ice on the sea bend. If it turned into gas,
there would be a global disaster. Lifer thinks that this
may be what happened two hundred and fifty million years ago.
Speaker 6: If we look at this massive extinction as comparable to
a genocidal crime on an unimaginable scale, and we ask
ourselves who are the criminal suspects, who's responsible? We'd look
at the evidence and at the top of the short
list is methane hydrates because of the vast size and
they're known instability.
Speaker 1: Frozen methane is ultrasensitive to heat. Raising its temperature by
even a few degrees can destabilize it and trigger the
release of this powerful greenhouse gas.
Speaker 6: If the atmosphere warms for any particular reason, the ocean
will methane hydrate will release methane. This will warm the atmosphere,
leading to warmer temperatures and even more methane hydrate in
the releasing its methane to the atmosphere, a positive feedback cycle.
Speaker 1: Two hundred and fifty million years ago, billions of tons
of volcanic gases produced by the Siberian traps triggered one
of these cycles. The eruptions increased global temperature by ten degrees,
enough to thaw the frozen methane hydrate at the bottom
of the oceans and release billions of tons of potent
greenhouse gas into the Earth's atmosphere. The temperature went up
another ten degrees. The world was now twenty degrees hotter.
Life couldn't adapt to the increase in heat and the
sudden change in climate. Now nearly all life died out.
First to go the remaining vegetation, next the few surviving herbivores,
and with them the last of the carnivores vanished. Earth's
food chain was more than broken. It hardly existed at all. Yet,
in spite of the overwhelming series of catastrophes, new life
and eventually humans, do evolve. We owe our existence to
an unlikely group of four legged heroes. Two hundred and
fifty million years ago, the planet had been brought to
its knees by savage volcanic eruptions. The toxic gases they
released created worldwide climate chaos and wiped out most life
on Earth. For the planet's dominant species, there was no
hope of survival.
Speaker 4: For something like a gogonopsian, it would have seen a
world which would be changing. The very animals that it
was eating would were becoming rarer. It were getting a
heck of a lot hotter, so terminal times for the
gorgonopsians and all around it as well.
Speaker 1: For these fearsome predators and for most living things, it
was the end of the line. But in evolutionary terms,
it was a new beginning.
Speaker 5: Catastrophes can reset the evolutionary clock. That means that evolution,
the whole direction of evolution, perhaps will change because the
dominant species disappear, and then other species that were taking
a less significant role before the event have their chance.
Speaker 1: Two hundred and fifty million years ago, the mass extinction
provided a priceless evolutionary opportunity to a small burrowing animal.
These are cynodonts. They'd been a favorite snack for gerganopsians,
but by burrowing underground, they'd stayed out of their predator's reach,
and it proved to be a useful habit. When climate
change scorched the earth's surface, tubers and roots underground provided
them with food and water. In South Africa's Careou Basin,
paleontologist Roger Smith has made an important discovery.
Speaker 2: We're looking at a burrow cast in the early Triassic,
and we know from fossils that have been found in
the ends of these casts that they are Cynodon. Cynodonts
were digging burrows during the end perme extinction event, and
it's very likely that that was one of the reasons
why it was able to survive the great drought at
that time.
Speaker 1: After the mouse extinction, these cynodonts went on to become
one of the dominant species in the New World. Without them,
we wouldn't be here today.
Speaker 2: One of the cynodont line eventually became a mammal, and
had it not been for the survivor through the cynodont line,
mammals would not have existed and evolved, and nor would we.
So we have a lot to thank the cynodonts for.
Speaker 1: Quarter of a billion years ago. Life suffered a devastating blow,
only to bounce back with new species and ecosystems. But
the same kind of catastrophe that gave our earliest ancestors
its chance could happen again. Eruptions like Iceland's Larkie come
roughly every twenty million years. Gigantic ones like the Siberian
Traps are rarer still they happen every few hundred million years,
but they do happen.
Speaker 5: It might shock be able to realize that the Earth
can cause extreme devastation, and of course there's nothing that
human beings with all their technology, could do to counter that.
So that if there were to be an eruption today
on the scale of Siberian Traps, it'd be hard to
know how large numbers of human beings could protect themselves
from it, So very likely that would be unbelievable death
and destruction. Nobody would be safe.
Speaker 1: But the biggest threat to mankind's future might not be
a naturally occurring phenomenon. For the first time in history,
the dominant species on Earth is upsetting the delicate balance
of its own ecosystem. Our production of carbon dioxide is
having a catastrophic impact on Earth systems.
Speaker 3: We have the potential to release two or three thousand
gigatons of carbon dioxide to the atmosphere in the next
couple centuries. When we look at the Siberian Trap volcanism,
we're talking about maybe similar quantities of carbon dioxide released
but over millennia to maybe a million years, And so
we're taking the whole Siberian Trap event and compressing it
into the timescale of human activity one or two centuries,
and that's scary.
Speaker 1: It's already causing the plant to heat up, and scientists
fear the runaway global warming of the past could happen
again in the future. With more than thirty trillion tons
of methane locked up as hydrates on the seafloor, the
potential for another hydrate meltdown is as real today as
it was two hundred and fifty million years ago, but
this time we would have started it.
Speaker 4: I'm sure that if you carry on what we're doing
today in terms of pollution, we will cause a catastrophe.
But how quickly is the big question.
Speaker 1: The end Permian extinction was one of the most important
chapters in the story of the evolution of life. It
nearly wiped out life itself from the face of the planet.
The few survivors became our direct ancestors. Without this mass
extinction event, we probably wouldn't be here at all.
Speaker 4: M