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We are entranced
by the beauty of our planet.
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00:00:31,763 --> 00:00:34,323
Just take in this view
for a moment.
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00:00:34,323 --> 00:00:39,403
Lush green meadows, thick forest,
jagged mountain peaks -
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00:00:39,403 --> 00:00:41,123
it's magnificent.
5
00:00:46,043 --> 00:00:48,483
But whilst we appreciate
that beauty,
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00:00:48,483 --> 00:00:53,243
I think sometimes we forget that
all of this is so fleeting.
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00:00:53,243 --> 00:00:56,403
For the last four-and-a-half
billion years,
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00:00:56,403 --> 00:01:00,963
our Earth has been a constantly
changing ball of rock,
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00:01:00,963 --> 00:01:05,643
transforming itself
over and over again.
10
00:01:05,643 --> 00:01:09,283
It's more fragile
than we like to acknowledge.
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00:01:09,283 --> 00:01:12,723
It's more indifferent to us
than we care to admit.
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00:01:16,043 --> 00:01:19,963
Now, thanks to pioneering
new science,
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00:01:19,963 --> 00:01:25,483
we can explore our planet's
four-and-a-half-billion-year story
14
00:01:25,483 --> 00:01:26,963
like never before.
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00:01:30,043 --> 00:01:34,643
In this series, we'll witness
five pivotal moments
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00:01:34,643 --> 00:01:36,283
in Earth's history...
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00:01:39,283 --> 00:01:41,363
..moments of drama...
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00:01:42,923 --> 00:01:44,443
..of crisis...
19
00:01:45,763 --> 00:01:48,043
..and of rebirth...
20
00:01:51,763 --> 00:01:55,603
..events that shaped
the planet we live on.
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00:01:58,243 --> 00:02:03,123
Wherever you are, you have beneath
your feet the most precious object
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00:02:03,123 --> 00:02:04,883
in the universe -
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00:02:04,883 --> 00:02:09,203
a living, breathing,
life-sustaining world.
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00:02:09,203 --> 00:02:11,843
And this is its story.
25
00:02:48,283 --> 00:02:54,043
It can feel as if our living world
was somehow inevitable...
26
00:03:00,323 --> 00:03:03,963
..that ours is a planet
with all the right ingredients
27
00:03:03,963 --> 00:03:06,523
for a rich assortment of life...
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00:03:08,403 --> 00:03:13,363
..not only to arise,
but to flourish and endure.
29
00:03:14,843 --> 00:03:20,203
But, in fact, it's death that is
the only true inevitability.
30
00:03:21,483 --> 00:03:25,523
There's an uncomfortable truth
about life on Earth.
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00:03:25,523 --> 00:03:29,563
You see, this great diversity,
this weird, wonderful
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00:03:29,563 --> 00:03:33,443
and beautiful mix of species,
of plants, animals and fungi
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00:03:33,443 --> 00:03:38,323
are all only here because
something else has died -
34
00:03:38,323 --> 00:03:43,483
in fact, because an enormous number
of other things have died.
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00:03:43,483 --> 00:03:47,723
If we were to take the sum total
of every living thing
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00:03:47,723 --> 00:03:52,963
on our planet today, it would add up
to less than 1% of those
37
00:03:52,963 --> 00:03:56,043
that have ever existed on Earth.
38
00:03:56,043 --> 00:04:00,923
But this colossal loss of life
is not a tragedy.
39
00:04:00,923 --> 00:04:04,283
Extinction is a vital part
of evolution.
40
00:04:07,603 --> 00:04:10,003
If nothing ever went extinct,
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00:04:10,003 --> 00:04:13,363
there would be no room for
new species to evolve.
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00:04:14,723 --> 00:04:19,803
Over time, extinction helped create
our rich living world.
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00:04:21,243 --> 00:04:24,083
But our planet walks a tightrope.
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00:04:25,883 --> 00:04:28,603
If extinction goes unchecked,
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00:04:28,603 --> 00:04:32,203
the complex web of life crumbles.
46
00:04:37,123 --> 00:04:42,083
Imagine 90% of species
suddenly dying -
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00:04:42,083 --> 00:04:46,443
not just a few endangered plants
or animals becoming extinct,
48
00:04:46,443 --> 00:04:49,043
or a handful of
ecosystems disappearing,
49
00:04:49,043 --> 00:04:54,363
but nine out of ten living things
wiped off the face of the Earth.
50
00:04:58,923 --> 00:05:03,643
Imagine what that Earth would
look like in the aftermath -
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00:05:03,643 --> 00:05:08,163
shattered, broken,
bereft of the beautiful complexity
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00:05:08,163 --> 00:05:10,123
that we take for granted today.
53
00:05:13,483 --> 00:05:18,923
We may think modern climate change
is our planet's darkest hour,
54
00:05:18,923 --> 00:05:21,603
or the loss of the dinosaurs,
55
00:05:21,603 --> 00:05:24,323
but the Earth has seen worse.
56
00:05:26,043 --> 00:05:30,323
This is the story of the greatest
mass extinction event
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00:05:30,323 --> 00:05:31,883
in Earth's history.
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00:05:36,803 --> 00:05:42,723
Something caused our planet's
life-support systems to fail,
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00:05:42,723 --> 00:05:47,483
wiping out most of
the species on Earth.
60
00:05:48,883 --> 00:05:51,883
And this is not
an apocalyptic vision,
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00:05:51,883 --> 00:05:53,843
not a doomsday prophesy.
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00:05:53,843 --> 00:05:56,403
This actually happened.
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00:05:56,403 --> 00:06:00,043
252 million years ago,
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00:06:00,043 --> 00:06:05,243
the Earth turned on the life
that it had nurtured for so long.
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00:06:09,323 --> 00:06:14,563
What does it take to destroy
almost all life on Earth?
66
00:06:18,403 --> 00:06:20,403
And could it happen again?
67
00:06:26,043 --> 00:06:29,603
Well, the answer lies in
Earth's deep history...
68
00:06:35,843 --> 00:06:40,483
..in a time long before humans
transformed the planet's surface...
69
00:06:46,043 --> 00:06:48,643
..before the last Ice Age...
70
00:06:53,403 --> 00:06:57,523
..before the asteroid impact
wiped out the dinosaurs...
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00:07:03,403 --> 00:07:07,443
..in fact, back to a time
before dinosaurs
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00:07:07,443 --> 00:07:09,523
even existed at all.
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00:07:28,763 --> 00:07:34,923
From space, the Earth in the
Late Permian is a strange sight.
74
00:07:34,923 --> 00:07:38,283
From one side, a water world,
75
00:07:38,283 --> 00:07:39,923
no land in sight.
76
00:07:45,523 --> 00:07:50,803
But as the planet turns,
something else creeps into view...
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00:07:54,203 --> 00:07:59,043
..all the Earth's major landmasses
clustered as one.
78
00:08:00,843 --> 00:08:03,643
This is Pangea...
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00:08:08,723 --> 00:08:12,323
..a supercontinent rich with life.
80
00:08:18,923 --> 00:08:23,483
Coastal waters teem with weird
and wonderful creatures.
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At once both alien,
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00:08:28,683 --> 00:08:31,363
yet eerily familiar.
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00:08:35,163 --> 00:08:41,723
And in lush forests, a cacophony
of animal cries fill the air.
84
00:09:09,523 --> 00:09:12,883
In many ways,
the Earth in the Late Permian
85
00:09:12,883 --> 00:09:15,163
was like the Earth we have today -
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00:09:15,163 --> 00:09:18,323
millions of species of plants
and animals, living together
87
00:09:18,323 --> 00:09:20,763
in complex, interconnected webs
88
00:09:20,763 --> 00:09:24,043
which are nurturing
and self-sustaining.
89
00:09:24,043 --> 00:09:28,643
But in other ways,
it was a very alien world.
90
00:09:28,643 --> 00:09:35,563
This was a time long before mammals
or even dinosaurs walked the Earth.
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00:09:35,563 --> 00:09:39,563
But life was no less remarkable.
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Scuttling around in the scrub
of the Late Permian,
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00:09:42,483 --> 00:09:44,563
you might have found one of these.
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00:09:44,563 --> 00:09:49,083
This is the cast of a beautiful
fossil of Nycteroleter.
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00:09:49,083 --> 00:09:53,963
It's part of an extinct group of
reptiles, and fed on things
96
00:09:53,963 --> 00:09:57,563
like proto-cockroaches,
dragonflies, millipedes.
97
00:09:57,563 --> 00:09:58,843
It's got quite large eyes,
98
00:09:58,843 --> 00:10:01,003
suggesting that it might have
been nocturnal,
99
00:10:01,003 --> 00:10:05,003
and we also know that it had
really good hearing -
100
00:10:05,003 --> 00:10:07,683
something quite unique
for animals of that time.
101
00:10:08,843 --> 00:10:11,083
But then, look at this chap.
102
00:10:11,083 --> 00:10:12,803
It's Dvinia.
103
00:10:12,803 --> 00:10:14,723
It would've grown to about
50 centimetres.
104
00:10:14,723 --> 00:10:16,883
Looked like a small dog.
105
00:10:16,883 --> 00:10:20,963
Neither a mammal, nor a reptile,
it's got forward-facing eyes.
106
00:10:20,963 --> 00:10:23,803
It was perhaps
a predator of some kind.
107
00:10:23,803 --> 00:10:27,403
But, look, from the top, you can see
it's got really wide cheeks,
108
00:10:27,403 --> 00:10:30,723
and the remains here of perhaps
a sagittal crest,
109
00:10:30,723 --> 00:10:34,323
suggesting that it had very
powerful muscles, a powerful bite.
110
00:10:34,323 --> 00:10:38,323
In fact, it might have been fishing
for shellfish down on the beach
111
00:10:38,323 --> 00:10:42,123
and crunching them up with
its powerful jaws.
112
00:10:42,123 --> 00:10:45,203
But last, and perhaps
most impressive,
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this is a magnificent specimen of
a super predator, Inostrancevia.
114
00:10:51,803 --> 00:10:53,163
What an animal.
115
00:10:53,163 --> 00:10:56,483
Just look at those
sabre-tooth teeth there.
116
00:10:56,483 --> 00:10:58,083
Now, those are slashing tools.
117
00:10:58,083 --> 00:11:01,923
Those are for wounding prey,
waiting for it to bleed to death,
118
00:11:01,923 --> 00:11:06,363
and then catching up with it
and swallowing large chunks whole.
119
00:11:06,363 --> 00:11:09,203
This animal would've grown
to about 3 metres in length
120
00:11:09,203 --> 00:11:11,083
and very fast-moving
121
00:11:11,083 --> 00:11:15,163
and been terrorising
the large herbivores of its time.
122
00:11:15,163 --> 00:11:17,923
What a fantastic beast
it must have been.
123
00:11:20,603 --> 00:11:22,523
But by the end of the Permian,
124
00:11:22,523 --> 00:11:26,123
along with nearly every other
living thing on Earth,
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00:11:26,123 --> 00:11:28,323
they would be dead.
126
00:11:50,083 --> 00:11:52,963
We're not certain how it started,
127
00:11:52,963 --> 00:11:56,403
but deep inside the ancient Earth,
128
00:11:56,403 --> 00:11:59,643
superheated rock is rising...
129
00:12:01,923 --> 00:12:05,563
..pushing upwards against
the solid outer crust...
130
00:12:09,363 --> 00:12:12,683
..until it can take no more.
131
00:12:17,283 --> 00:12:19,243
The crust fails.
132
00:12:29,803 --> 00:12:33,203
The landscape physically torn apart,
133
00:12:33,203 --> 00:12:35,643
as lava floods onto the surface...
134
00:12:36,843 --> 00:12:39,963
..forming great curtains of fire.
135
00:12:45,083 --> 00:12:49,923
This is just the beginning of
the most deadly volcanic event
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00:12:49,923 --> 00:12:51,323
in Earth's history.
137
00:13:01,763 --> 00:13:05,603
We can get clues to what
these ancient eruptions were like
138
00:13:05,603 --> 00:13:08,043
by studying modern volcanoes.
139
00:13:16,163 --> 00:13:19,923
This is Tajogaite Volcano,
in the Canary Islands,
140
00:13:19,923 --> 00:13:23,843
and in September of 2021,
the ground here split
141
00:13:23,843 --> 00:13:28,403
and tonnes of lava, ash
and toxic gases exploded,
142
00:13:28,403 --> 00:13:31,003
shaking the entire island.
143
00:13:40,043 --> 00:13:41,803
Over three months,
144
00:13:41,803 --> 00:13:48,763
170 million cubic metres of lava
poured onto the surface.
145
00:13:51,163 --> 00:13:55,083
It was the first eruption
on the island in 50 years.
146
00:14:03,003 --> 00:14:07,403
More than 7,000 people had
to flee their homes.
147
00:14:19,843 --> 00:14:23,243
This volcano spewed out
enough lava to fill around
148
00:14:23,243 --> 00:14:26,243
70,000 Olympic-sized swimming pools,
149
00:14:26,243 --> 00:14:30,203
and that lava covered an area around
ten square kilometres -
150
00:14:30,203 --> 00:14:32,323
which sounds pretty impressive,
151
00:14:32,323 --> 00:14:38,363
but it's just a teaspoon compared
to those at the end of the Permian.
152
00:14:38,363 --> 00:14:41,003
252 million years ago,
153
00:14:41,003 --> 00:14:47,563
around four million cubic kilometres
of lava, ash and toxic gases
154
00:14:47,563 --> 00:14:51,203
erupted in a series
of volcanic explosions
155
00:14:51,203 --> 00:14:55,243
that went on for 2 million years.
156
00:14:55,243 --> 00:14:59,803
The Permian eruptions
were 1,000 times greater than
157
00:14:59,803 --> 00:15:01,883
any witnessed by humans.
158
00:15:03,563 --> 00:15:07,443
And the ancient lava
is still with us.
159
00:15:07,443 --> 00:15:09,563
In Northwestern Siberia,
160
00:15:09,563 --> 00:15:13,843
beneath a landscape of swamps
and flood plains,
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00:15:13,843 --> 00:15:18,483
scientists have discovered
a colossal lava field,
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00:15:18,483 --> 00:15:23,043
dated a little over
250 million years old...
163
00:15:25,283 --> 00:15:28,843
..lava that covers over
two-and-a-half million
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00:15:28,843 --> 00:15:30,363
square kilometres...
165
00:15:33,003 --> 00:15:38,083
..enough to bury the entire
continent of Australia
166
00:15:38,083 --> 00:15:40,083
hundreds of metres deep.
167
00:15:46,403 --> 00:15:53,643
252 million years ago,
Northern Pangea was hell on Earth.
168
00:15:57,843 --> 00:16:03,043
Fire fountains blast volcanic
material over six miles up
169
00:16:03,043 --> 00:16:04,403
into the atmosphere...
170
00:16:08,243 --> 00:16:12,083
..burning millions of square miles
of forests.
171
00:16:21,723 --> 00:16:25,763
And clouds bloom high into
the atmosphere,
172
00:16:25,763 --> 00:16:27,443
blocking out the sun.
173
00:16:32,403 --> 00:16:35,003
Plants wilt and die...
174
00:16:40,243 --> 00:16:42,683
..ash falls like snow...
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00:16:46,843 --> 00:16:52,603
..as vast swathes of Northern Pangea
lie in ruins.
176
00:17:01,763 --> 00:17:06,363
These eruptions are on a scale
almost beyond imagination.
177
00:17:08,603 --> 00:17:15,563
But lava still only covers
less than 1% of Pangea's surface.
178
00:17:15,563 --> 00:17:19,963
And elsewhere, something curious
is happening.
179
00:17:24,723 --> 00:17:28,403
A strange haze hangs in the air.
180
00:17:34,923 --> 00:17:38,763
Nutrient-rich volcanic ash
and sulphur,
181
00:17:38,763 --> 00:17:44,443
transported thousands of miles,
reflect the sun's rays...
182
00:17:46,043 --> 00:17:49,243
..pushing global
temperatures down...
183
00:17:56,243 --> 00:18:01,363
..and in places, causing a surge
of plant life to flourish.
184
00:18:07,523 --> 00:18:10,083
But death is coming.
185
00:18:26,163 --> 00:18:29,483
I've come to an outcrop
in Northern Italy,
186
00:18:29,483 --> 00:18:35,243
made of rock that formed at the same
time as those ancient eruptions.
187
00:18:38,283 --> 00:18:41,523
It's a fossilised crime scene
188
00:18:41,523 --> 00:18:44,443
with a chilling tale to tell.
189
00:18:46,643 --> 00:18:52,563
Look at this thin, black seam
that runs all the way down here.
190
00:18:55,363 --> 00:18:57,603
It looks like coal to me,
191
00:18:57,603 --> 00:19:00,443
which would indicate that
at one point...
192
00:19:02,283 --> 00:19:03,843
..it was full of plant life.
193
00:19:03,843 --> 00:19:05,923
Probably full of lots
of other life, too.
194
00:19:07,843 --> 00:19:11,203
Coal is little more than
ancient organic matter
195
00:19:11,203 --> 00:19:14,803
that's been subjected to
extreme temperatures and pressures
196
00:19:14,803 --> 00:19:17,123
over millions of years.
197
00:19:17,123 --> 00:19:19,643
So, where we find coal today,
198
00:19:19,643 --> 00:19:22,563
we know there was once life.
199
00:19:22,563 --> 00:19:26,483
But the rocks above it here
tell an altogether different story.
200
00:19:32,963 --> 00:19:36,083
They're grey, dull,
look a bit boring,
201
00:19:36,083 --> 00:19:38,603
a bit of a geological mush.
202
00:19:38,603 --> 00:19:40,763
But that's the point -
203
00:19:40,763 --> 00:19:44,883
because, aside from a few
fossil microorganisms,
204
00:19:44,883 --> 00:19:50,563
scientists have found very little
evidence of life in these rocks.
205
00:19:50,563 --> 00:19:56,123
So, what they are telling us
is that 252 million years ago,
206
00:19:56,123 --> 00:19:59,883
the landscape here
was almost devoid of life.
207
00:20:02,403 --> 00:20:08,963
In a geological blink of an eye,
almost all life here vanished.
208
00:20:08,963 --> 00:20:12,803
You can't help but feel
a certain sense of sadness.
209
00:20:12,803 --> 00:20:16,243
Holding this makes it so tangible.
210
00:20:19,283 --> 00:20:23,563
This was death on
an unimaginable scale.
211
00:20:25,203 --> 00:20:29,323
But there's no evidence of lava here
at all.
212
00:20:31,003 --> 00:20:34,523
When these rocks were laid down
in this part of Italy,
213
00:20:34,523 --> 00:20:38,403
they were thousands of miles away
from the eruptions in the north -
214
00:20:38,403 --> 00:20:42,083
certainly too far away
for any direct impacts.
215
00:20:42,083 --> 00:20:44,723
But what's interesting
is that geologists
216
00:20:44,723 --> 00:20:49,443
have found this line of death
all over the planet -
217
00:20:49,443 --> 00:20:52,443
China, Australia, South Africa.
218
00:20:52,443 --> 00:20:56,123
And no matter how far away
from the lava fields,
219
00:20:56,123 --> 00:20:58,803
there's a deathly silence
in the fossil record.
220
00:21:01,203 --> 00:21:07,043
The question is, what could have
killed this many creatures?
221
00:21:07,043 --> 00:21:12,043
What could have wiped out
almost all life on Earth?
222
00:21:31,643 --> 00:21:35,483
Something more than lava
was emerging from the Earth
223
00:21:35,483 --> 00:21:37,203
in Northern Pangea.
224
00:21:42,003 --> 00:21:47,403
Billions of tonnes of gases are
injected high into the atmosphere.
225
00:21:56,243 --> 00:21:59,403
Water vapour, sulphur dioxide...
226
00:22:01,203 --> 00:22:06,203
..but primarily a gas
we all know too well -
227
00:22:06,203 --> 00:22:09,923
the greenhouse gas
carbon dioxide.
228
00:22:30,163 --> 00:22:33,523
We're all becoming depressingly
familiar with what happens
229
00:22:33,523 --> 00:22:39,243
when you pump huge quantities of
carbon dioxide into the atmosphere.
230
00:22:39,243 --> 00:22:41,563
It's an experiment we've been
running ourselves
231
00:22:41,563 --> 00:22:43,643
for more than 100 years.
232
00:22:43,643 --> 00:22:48,003
And the more the CO2,
the more the heat is locked in,
233
00:22:48,003 --> 00:22:50,923
and the hotter our Earth becomes.
234
00:22:52,003 --> 00:22:55,563
Global warming isn't
a localised effect.
235
00:22:55,563 --> 00:22:58,123
The whole planet feels the burn.
236
00:22:59,363 --> 00:23:00,963
Here we are, yeah, dead ahead.
237
00:23:00,963 --> 00:23:03,003
No creature is safe.
238
00:23:03,003 --> 00:23:06,323
You've got a little feeding party
taking place here at the moment.
239
00:23:06,323 --> 00:23:08,523
Oh, look at that!
240
00:23:09,523 --> 00:23:11,923
Oh, yes, yes!
241
00:23:15,283 --> 00:23:18,403
Sorry to be a child,
but it's always...
242
00:23:18,403 --> 00:23:20,923
Oh, oh, oh, oh!
243
00:23:20,923 --> 00:23:23,323
Oh, I just saw it catch a fish!
244
00:23:23,323 --> 00:23:24,403
Oh!
245
00:23:25,923 --> 00:23:28,283
There are several species here.
246
00:23:28,283 --> 00:23:29,723
Bottlenose...
247
00:23:31,923 --> 00:23:35,963
..common, rough tooth, spotted.
248
00:23:37,563 --> 00:23:41,723
And dolphins, of course, can live
in much warmer waters than these.
249
00:23:41,723 --> 00:23:44,323
So, you might imagine
they're not the sorts of creatures
250
00:23:44,323 --> 00:23:47,443
that would be harmed
by global warming.
251
00:23:47,443 --> 00:23:51,643
But sadly, I've got to tell you,
these dolphins are in trouble.
252
00:23:58,003 --> 00:24:02,763
It's not always the temperature
that poses a danger to life.
253
00:24:02,763 --> 00:24:06,123
In fact, for some,
the heat is a blessing.
254
00:24:08,363 --> 00:24:11,043
Let's see what
I've managed to catch.
255
00:24:12,483 --> 00:24:14,803
Wow, rather a lot.
256
00:24:14,803 --> 00:24:19,043
This mass of detritus here
is plankton,
257
00:24:19,043 --> 00:24:22,203
much of it phytoplankton, algae.
258
00:24:22,203 --> 00:24:25,603
Now, most of the organisms
wouldn't hurt anything,
259
00:24:25,603 --> 00:24:29,043
but there is one species,
Karenia Brevis -
260
00:24:29,043 --> 00:24:31,803
well, that's an algae
with a superpower.
261
00:24:31,803 --> 00:24:34,283
You see, when the water
warms up here,
262
00:24:34,283 --> 00:24:37,683
it goes into a reproductive frenzy,
263
00:24:37,683 --> 00:24:41,323
producing blooms
many hundreds of times greater
264
00:24:41,323 --> 00:24:43,203
than it normally would.
265
00:24:43,203 --> 00:24:45,483
But what's good for the algae,
it turns out,
266
00:24:45,483 --> 00:24:48,003
is not so good for the dolphins.
267
00:24:48,003 --> 00:24:52,803
Because recent research has shown
that this is extremely toxic.
268
00:24:52,803 --> 00:24:55,203
So, the small fish eat the algae,
269
00:24:55,203 --> 00:24:57,283
the bigger fish eat the small fish,
270
00:24:57,283 --> 00:24:59,883
the dolphins the larger fish.
271
00:24:59,883 --> 00:25:03,123
And this organism
has been implicated
272
00:25:03,123 --> 00:25:06,003
in the deaths of dozens of dolphins,
273
00:25:06,003 --> 00:25:08,443
found dead floating in the sea here.
274
00:25:10,403 --> 00:25:14,843
Rising temperatures affect
different parts of the food chain
275
00:25:14,843 --> 00:25:16,963
in different ways,
276
00:25:16,963 --> 00:25:20,803
throwing ecosystems
out of balance...
277
00:25:20,803 --> 00:25:23,603
..often with deadly results.
278
00:25:25,083 --> 00:25:27,403
You see, when it comes
to global warming,
279
00:25:27,403 --> 00:25:30,523
it's not the actual heat
that kills those creatures.
280
00:25:30,523 --> 00:25:34,723
It's the increases or decreases
in plant or animal populations
281
00:25:34,723 --> 00:25:40,523
which disrupt those long-evolved,
stable, beautiful ecosystems.
282
00:25:40,523 --> 00:25:46,163
Death by global warming
is not short, sharp, and painless.
283
00:25:46,163 --> 00:25:48,923
It's prolonged and torturous.
284
00:26:06,883 --> 00:26:09,923
As the temperatures rise
across Pangea...
285
00:26:16,563 --> 00:26:18,643
..trees begin to die.
286
00:26:33,683 --> 00:26:37,443
Holes appear in
the once-thick canopy,
287
00:26:37,443 --> 00:26:40,483
bathing the ground in sunlight.
288
00:26:45,803 --> 00:26:48,403
For some, it's an opportunity.
289
00:26:49,403 --> 00:26:51,443
Weed-like plants flourish,
290
00:26:51,443 --> 00:26:53,723
like spore-bearing lycophytes.
291
00:26:57,083 --> 00:26:59,563
No longer struggling in the shadows,
292
00:26:59,563 --> 00:27:02,283
in times of stress, they thrive.
293
00:27:06,123 --> 00:27:08,923
And foreign species appear.
294
00:27:08,923 --> 00:27:13,523
Woody, seed-bearing cycads
that once only grew in the tropics
295
00:27:13,523 --> 00:27:16,283
are now abundant
closer to the Poles.
296
00:27:21,403 --> 00:27:26,043
Surprisingly, some areas
are now more diverse
297
00:27:26,043 --> 00:27:28,323
than before the warming began.
298
00:27:29,563 --> 00:27:33,883
But this is an ecosystem
out of balance.
299
00:27:37,123 --> 00:27:39,283
A few more degrees' warming,
300
00:27:39,283 --> 00:27:42,003
and the living world will crumble.
301
00:27:57,163 --> 00:28:00,843
But then something strange happens.
302
00:28:03,403 --> 00:28:06,603
Red hot rivers of lava...
303
00:28:06,603 --> 00:28:09,243
..turn to solid rock.
304
00:28:11,203 --> 00:28:14,003
Just as quickly as they started,
305
00:28:14,003 --> 00:28:17,163
the eruptions fall silent.
306
00:28:30,283 --> 00:28:33,443
The CO2 released
from the Permian lavas
307
00:28:33,443 --> 00:28:36,763
likely dwarfed human emissions
to date.
308
00:28:39,123 --> 00:28:43,403
But even that may have been
just part of the story.
309
00:28:47,283 --> 00:28:49,083
These eruptions would have produced
310
00:28:49,083 --> 00:28:51,763
an inordinate amount
of carbon dioxide -
311
00:28:51,763 --> 00:28:53,363
gigatons of the stuff,
312
00:28:53,363 --> 00:28:56,203
certainly enough to manifest
some global warming,
313
00:28:56,203 --> 00:29:00,283
perhaps in the realm of an increase
of 5 or 6 degrees Celsius,
314
00:29:00,283 --> 00:29:02,123
something like that.
315
00:29:02,123 --> 00:29:05,163
Now, that's a substantial amount
of heating,
316
00:29:05,163 --> 00:29:08,803
but it's not significant enough
to account for all of the deaths
317
00:29:08,803 --> 00:29:11,203
that we see in the fossil record.
318
00:29:11,203 --> 00:29:13,483
Yes, there would have
been extinctions,
319
00:29:13,483 --> 00:29:17,203
but not 90% of all life on Earth.
320
00:29:29,043 --> 00:29:33,003
The effects of carbon dioxide
can be lethal.
321
00:29:33,003 --> 00:29:36,563
But some scientists think
there was another killer.
322
00:29:39,803 --> 00:29:42,763
The volcanism hadn't stopped.
323
00:29:42,763 --> 00:29:46,883
It had just entered
a terrifying new phase.
324
00:29:49,763 --> 00:29:52,363
Beneath the desolate lava field...
325
00:29:53,363 --> 00:29:57,123
..hot magma still flows,
326
00:29:57,123 --> 00:30:00,763
forming great reservoirs
underground...
327
00:30:00,763 --> 00:30:04,963
..and slowly baking
the Earth's crust.
328
00:30:17,963 --> 00:30:20,523
The rocks underground were older -
329
00:30:20,523 --> 00:30:24,443
hundreds of millions of years
older than the land above.
330
00:30:24,443 --> 00:30:26,683
And amongst them,
331
00:30:26,683 --> 00:30:29,843
there was plenty of this stuff -
332
00:30:29,843 --> 00:30:33,323
coal and other rocks rich in carbon.
333
00:30:33,323 --> 00:30:36,443
Now, what happens
when magma meets coal?
334
00:30:36,443 --> 00:30:42,323
Well, the coal burns, releasing
yet more dangerous carbon dioxide.
335
00:30:42,323 --> 00:30:44,283
But that was just the half of it.
336
00:30:44,283 --> 00:30:46,883
You see, it wasn't just coal.
337
00:30:46,883 --> 00:30:50,563
There was also lots of salt.
338
00:30:50,563 --> 00:30:56,803
And salt like this can form
when ancient lakes and seas dry up.
339
00:30:56,803 --> 00:30:59,923
And when magma comes into contact
with salt,
340
00:30:59,923 --> 00:31:02,203
things get really nasty.
341
00:31:04,883 --> 00:31:07,163
The salt begins to bake,
342
00:31:07,163 --> 00:31:12,563
releasing toxic halogen gases
rich in bromine and chlorine -
343
00:31:12,563 --> 00:31:17,403
archenemies of the Earth's
fragile ozone layer,
344
00:31:17,403 --> 00:31:23,923
that thin layer that protects us
from the sun's most harmful rays.
345
00:31:23,923 --> 00:31:28,243
So, what I'm trying to say here
is that the magma had found its way
346
00:31:28,243 --> 00:31:32,723
into the worst possible place
on the planet.
347
00:31:32,723 --> 00:31:35,283
It had created a time bomb.
348
00:31:41,563 --> 00:31:45,483
That magma begins to
heat up the coal and salt
349
00:31:45,483 --> 00:31:49,083
to a temperature of
800 degrees Celsius.
350
00:31:53,363 --> 00:31:56,603
A poisonous cocktail of gases
begins to build...
351
00:32:03,563 --> 00:32:07,283
..until the land above
can take no more.
352
00:32:40,483 --> 00:32:43,403
More CO2 floods the atmosphere,
353
00:32:43,403 --> 00:32:46,163
pushing global temperatures
even higher.
354
00:32:48,363 --> 00:32:53,843
But this time, there were also
those toxic halogen gases.
355
00:33:01,443 --> 00:33:06,603
We've seen the Earth's ozone layer
damaged in recent history,
356
00:33:06,603 --> 00:33:11,603
when artificial chemicals
created a so-called ozone hole.
357
00:33:13,043 --> 00:33:16,123
But in the Permian,
the halogens may have eroded
358
00:33:16,123 --> 00:33:18,883
the ozone layer away entirely...
359
00:33:21,523 --> 00:33:26,363
..bathing all life
in deadly UV radiation.
360
00:33:28,363 --> 00:33:32,083
Scientists have noticed something
strange going on with the pollen
361
00:33:32,083 --> 00:33:34,363
at the end of the Permian.
362
00:33:34,363 --> 00:33:36,083
Take a look at this.
363
00:33:36,083 --> 00:33:42,043
This is a highly-magnified image
of a modern pine pollen grain.
364
00:33:42,043 --> 00:33:44,803
And you can see it's got two
essential parts to its structure -
365
00:33:44,803 --> 00:33:47,603
the central circular part here,
the corpus,
366
00:33:47,603 --> 00:33:49,883
and then these winged sacchi.
367
00:33:49,883 --> 00:33:53,843
These are wind-pollinated
pollen species,
368
00:33:53,843 --> 00:33:56,363
and these help it float
through the air.
369
00:33:56,363 --> 00:33:58,683
But have a look at this.
370
00:33:58,683 --> 00:34:02,203
This is an image of a fossilised
coniferous pollen grain
371
00:34:02,203 --> 00:34:04,323
from the time of those eruptions.
372
00:34:04,323 --> 00:34:08,043
It's got three of these
wing structures.
373
00:34:08,043 --> 00:34:10,963
This one has four.
374
00:34:10,963 --> 00:34:15,083
These pollen grains are malformed,
misshapen and, in fact,
375
00:34:15,083 --> 00:34:17,123
if you look at this last one,
376
00:34:17,123 --> 00:34:21,003
this appear to have been
in the process of dividing,
377
00:34:21,003 --> 00:34:23,443
but somehow it's failed.
378
00:34:23,443 --> 00:34:26,483
These are mutant pollen grains,
379
00:34:26,483 --> 00:34:29,803
and it's thought that
the mutation was caused by
380
00:34:29,803 --> 00:34:32,603
the excessive UV radiation -
381
00:34:32,603 --> 00:34:38,843
evidence that those gases had really
damaged the Earth's ozone layer.
382
00:34:38,843 --> 00:34:41,003
Now, other theories are available.
383
00:34:41,003 --> 00:34:43,563
Others believe that, in fact,
it was acid rain
384
00:34:43,563 --> 00:34:48,243
that caused these mutations,
or merely the extreme heat.
385
00:34:48,243 --> 00:34:50,323
But whatever the cause,
386
00:34:50,323 --> 00:34:55,083
what's clear is that at this point,
life was on the brink.
387
00:35:10,483 --> 00:35:15,203
At first glance,
it seems nothing has changed.
388
00:35:15,203 --> 00:35:18,523
But this already fragile ecosystem
389
00:35:18,523 --> 00:35:23,363
has taken a lethal dose
of UV radiation.
390
00:35:23,363 --> 00:35:27,083
Healthy-looking plants
are now sterile.
391
00:35:29,603 --> 00:35:33,483
As individuals die,
they aren't replaced.
392
00:35:38,043 --> 00:35:42,603
Once-lush forests
become ravaged wastelands.
393
00:35:49,643 --> 00:35:54,323
The collapse in the oceans
is even more dramatic.
394
00:35:54,323 --> 00:35:57,283
Carbon dioxide reacts
with sea water,
395
00:35:57,283 --> 00:35:59,643
which begins to turn to acid.
396
00:36:04,563 --> 00:36:07,483
And oxygen levels plummet -
397
00:36:07,483 --> 00:36:10,723
in some places, dropping to zero.
398
00:36:13,603 --> 00:36:16,203
Algae blooms across the planet.
399
00:36:17,923 --> 00:36:21,163
As it decomposes,
it poisons the ocean
400
00:36:21,163 --> 00:36:24,123
with toxic hydrogen sulphide...
401
00:36:34,043 --> 00:36:40,483
..until the seafloor becomes
a foetid bed of slime.
402
00:36:44,283 --> 00:36:47,763
Sulphurous tides lap barren shores,
403
00:36:47,763 --> 00:36:51,163
and a smell like rotten eggs
hangs in the air.
404
00:36:53,443 --> 00:36:58,243
The Earth's rich complexity
has vanished,
405
00:36:58,243 --> 00:37:00,483
seemingly for good.
406
00:37:13,563 --> 00:37:15,643
It's been called many things -
407
00:37:15,643 --> 00:37:20,043
the Great Dying, the mother of
all mass extinction events
408
00:37:20,043 --> 00:37:24,043
or, simply, when life nearly died.
409
00:37:24,043 --> 00:37:27,163
The details are still a bit hazy.
410
00:37:27,163 --> 00:37:30,883
Was it a single short, sharp,
giant catastrophe,
411
00:37:30,883 --> 00:37:34,243
or a wave of smaller catastrophes?
412
00:37:34,243 --> 00:37:37,403
To what extent did the extinctions
occur on land
413
00:37:37,403 --> 00:37:40,523
versus extinctions in the water?
414
00:37:40,523 --> 00:37:42,763
The fossil record is patchy,
415
00:37:42,763 --> 00:37:45,043
so there's plenty of room
for academic debate.
416
00:37:45,043 --> 00:37:49,203
But the one thing that
almost everyone agrees upon
417
00:37:49,203 --> 00:37:53,043
is that these ancient eruptions
caused extinctions
418
00:37:53,043 --> 00:37:55,963
on an unprecedented scale.
419
00:37:55,963 --> 00:38:01,843
Figures frequently cited suggest
that 70% of land vertebrates
420
00:38:01,843 --> 00:38:06,083
and 96% of marine life
421
00:38:06,083 --> 00:38:09,763
vanished off the face of
the Earth forever.
422
00:38:12,203 --> 00:38:15,563
By the time the eruptions
finally stop,
423
00:38:15,563 --> 00:38:20,803
the average global temperature has
risen by over 10 degrees Celsius.
424
00:38:23,443 --> 00:38:29,843
Vast areas of the Earth's surface
are completely uninhabitable,
425
00:38:29,843 --> 00:38:33,443
and nearly all species are gone.
426
00:38:42,043 --> 00:38:47,283
The End-Permian extinction
has a virtually undisputed claim
427
00:38:47,283 --> 00:38:51,883
to being the worst moment
in the history of the Earth.
428
00:38:53,003 --> 00:38:57,683
But from the ashes,
there was a glimmer of hope,
429
00:38:57,683 --> 00:39:00,563
because life had survived somewhere.
430
00:39:00,563 --> 00:39:04,963
It must have.
Otherwise, we wouldn't be here.
431
00:39:06,443 --> 00:39:11,203
In a way, we are all survivors
of the Great Dying.
432
00:39:11,203 --> 00:39:17,723
You see, every living organism on
the planet has an ancient ancestor,
433
00:39:17,723 --> 00:39:21,403
perhaps millions, perhaps billions
of generations back,
434
00:39:21,403 --> 00:39:24,843
that not only survived
that mass extinction event
435
00:39:24,843 --> 00:39:28,603
but then went on to prosper
in the aftermath
436
00:39:28,603 --> 00:39:31,683
and then to repopulate the Earth.
437
00:39:34,683 --> 00:39:38,443
The Great Dying may have been
the end of one world,
438
00:39:38,443 --> 00:39:42,283
but it was also the beginning
of a new one.
439
00:39:53,163 --> 00:39:57,283
The Triassic Earth
is a shadow of its former self.
440
00:40:02,003 --> 00:40:05,123
Many creatures
seek refuge underground...
441
00:40:11,043 --> 00:40:13,923
..sheltering from
blistering temperatures
442
00:40:13,923 --> 00:40:16,283
and lethal UV radiation.
443
00:40:21,643 --> 00:40:27,003
Above ground, a single plant species
dominates the landscape.
444
00:40:28,203 --> 00:40:32,483
Pleuromeia - a weed-like plant
lucky enough to make it
445
00:40:32,483 --> 00:40:37,123
through the apocalypse and
find itself with few competitors.
446
00:40:41,083 --> 00:40:44,083
It helps provide sustenance
for the cockroaches,
447
00:40:44,083 --> 00:40:46,923
who also made it through unscathed.
448
00:40:51,883 --> 00:40:55,163
But just because
the eruptions have stopped
449
00:40:55,163 --> 00:40:59,243
doesn't mean that life's troubles
are over.
450
00:41:12,163 --> 00:41:15,843
The Early Triassic was dominated
by extreme heat.
451
00:41:15,843 --> 00:41:19,243
The fossil record shows us that
ocean temperatures could have been
452
00:41:19,243 --> 00:41:22,043
up to 14 degrees centigrade warmer
453
00:41:22,043 --> 00:41:24,403
than they were prior
to the eruptions.
454
00:41:24,403 --> 00:41:28,763
In some places, the water was
as warm as it is in a hot tub -
455
00:41:28,763 --> 00:41:31,723
too extreme for most
marine organisms.
456
00:41:35,523 --> 00:41:39,003
And on land, things weren't
faring much better.
457
00:41:39,003 --> 00:41:43,083
There were probably heatwaves of
up to 60 degrees centigrade -
458
00:41:43,083 --> 00:41:47,523
a temperature that would have
seriously inhibited photosynthesis.
459
00:41:47,523 --> 00:41:53,123
In fact, for the 10 million years
following the mass extinction event,
460
00:41:53,123 --> 00:41:58,363
we see no significant coal reserves
laid down anywhere on Earth.
461
00:41:58,363 --> 00:42:02,443
There simply weren't enough trees.
462
00:42:02,443 --> 00:42:07,483
For life to bounce back,
the planet needed to cool down.
463
00:42:14,963 --> 00:42:18,843
In normal times,
the Earth can cool itself -
464
00:42:18,843 --> 00:42:22,163
over thousands of years,
removing carbon dioxide
465
00:42:22,163 --> 00:42:26,523
from the atmosphere, in part
through reacting with rainwater.
466
00:42:27,803 --> 00:42:32,003
But vast areas of Pangea are desert.
467
00:42:32,003 --> 00:42:33,643
Little rain falls.
468
00:42:36,883 --> 00:42:41,483
So, it takes millions of years
for temperatures to drop.
469
00:42:52,923 --> 00:42:56,923
And even then, recovery is slow.
470
00:43:00,963 --> 00:43:06,003
The living world's struggling to
regain the diversity it once knew.
471
00:43:17,003 --> 00:43:19,603
But salvation was coming.
472
00:43:25,163 --> 00:43:31,443
High in the Dolomite Mountains
is evidence for a bizarre event,
473
00:43:31,443 --> 00:43:35,043
one that may have helped
life rebound.
474
00:43:38,363 --> 00:43:40,283
Look at this.
475
00:43:40,283 --> 00:43:43,323
Absolutely stunning.
476
00:43:43,323 --> 00:43:49,123
And these mountains were formed very
shortly after the extinction event,
477
00:43:49,123 --> 00:43:52,483
and they're made up of
sedimentary rock -
478
00:43:52,483 --> 00:43:55,363
layers of sediment on top
of one another,
479
00:43:55,363 --> 00:43:59,043
each corresponding to a time
in the Earth's history.
480
00:43:59,043 --> 00:44:01,323
The oldest rocks are at the bottom,
481
00:44:01,323 --> 00:44:03,563
around 238 million years old.
482
00:44:03,563 --> 00:44:05,363
The youngest at the top,
483
00:44:05,363 --> 00:44:08,283
about 200 million years old.
484
00:44:08,283 --> 00:44:11,443
Now, you might imagine that
if we wanted to uncover the secrets
485
00:44:11,443 --> 00:44:14,243
in these rocks, we'd take some,
break them open
486
00:44:14,243 --> 00:44:17,163
and look for some details -
but not here.
487
00:44:17,163 --> 00:44:21,963
The secrets in these rocks
are held in plain view.
488
00:44:21,963 --> 00:44:25,363
The key is the shape
of the mountains.
489
00:44:25,363 --> 00:44:30,323
It hints at a planetary intervention
that, just a few decades ago,
490
00:44:30,323 --> 00:44:33,483
we had no idea happened.
491
00:44:33,483 --> 00:44:38,523
Look, it starts steep at the bottom,
rises sharply,
492
00:44:38,523 --> 00:44:40,803
and then there's a shallow shelf,
493
00:44:40,803 --> 00:44:44,483
and then it rises steeply again
to the peak,
494
00:44:44,483 --> 00:44:46,523
currently in the clouds.
495
00:44:46,523 --> 00:44:51,043
But the bit that we're interested in
is that shallow slope,
496
00:44:51,043 --> 00:44:56,443
which corresponds to about 2 million
years in the Earth's history,
497
00:44:56,443 --> 00:44:59,363
and to a very strange
period of time.
498
00:45:01,083 --> 00:45:05,563
This shallow slope is evidence
of a softer rock type
499
00:45:05,563 --> 00:45:07,963
that's been eroded over the years.
500
00:45:10,363 --> 00:45:11,683
Here we go.
501
00:45:15,723 --> 00:45:18,443
This is a lump of sandstone.
502
00:45:18,443 --> 00:45:21,243
It's a soft sedimentary rock.
503
00:45:21,243 --> 00:45:23,363
The key is in the name.
504
00:45:23,363 --> 00:45:27,723
It's made up of sediments, like
sand, which wash off of the land,
505
00:45:27,723 --> 00:45:31,203
down into the rivers
and then down into the sea.
506
00:45:31,203 --> 00:45:34,723
So, what I'm holding here
is evidence of rain -
507
00:45:34,723 --> 00:45:36,323
rather a lot of rain,
508
00:45:36,323 --> 00:45:40,963
because in places,
this layer is about 80 metres deep.
509
00:45:42,643 --> 00:45:44,883
Sandstone is a common rock,
510
00:45:44,883 --> 00:45:47,923
but scientists have discovered
similar layers
511
00:45:47,923 --> 00:45:50,323
right across the planet,
512
00:45:50,323 --> 00:45:55,363
leading some to think this was
the result of a global deluge.
513
00:45:56,843 --> 00:45:59,723
Now, we're not precisely sure
why it started.
514
00:45:59,723 --> 00:46:02,643
It could have been
underwater volcanic activity
515
00:46:02,643 --> 00:46:04,683
disrupting the water cycle.
516
00:46:04,683 --> 00:46:07,203
But at some point in the Triassic,
517
00:46:07,203 --> 00:46:11,923
a time famed for being
excruciatingly hot and arid,
518
00:46:11,923 --> 00:46:14,083
it started to rain.
519
00:46:14,083 --> 00:46:17,683
And, boy, did it rain -
because that rain
520
00:46:17,683 --> 00:46:22,923
defined the Earth's climate
for almost 2 million years.
521
00:46:36,483 --> 00:46:41,003
18 million years
after the mass extinction,
522
00:46:41,003 --> 00:46:42,723
the heavens open...
523
00:46:45,043 --> 00:46:48,963
..a sudden increase in rainfall
across Pangea.
524
00:46:51,483 --> 00:46:54,123
The rain causes more extinctions...
525
00:46:56,003 --> 00:46:58,403
..but the planet is reborn.
526
00:47:06,883 --> 00:47:09,843
Where arid shrub land once stood...
527
00:47:11,363 --> 00:47:14,043
..lush forests now grow.
528
00:47:15,643 --> 00:47:19,883
It's been called
the greening of Triassic Earth,
529
00:47:19,883 --> 00:47:24,483
and it marked the beginning
of much of the life we know today.
530
00:47:36,443 --> 00:47:38,883
There were new species
of crocodiles...
531
00:47:41,003 --> 00:47:42,963
..amphibians...
532
00:47:46,123 --> 00:47:49,723
..even early ancestors
of modern mammals.
533
00:48:00,043 --> 00:48:03,403
But the mammals would have to
wait in the wings.
534
00:48:03,403 --> 00:48:07,683
Other creatures were set
to inherit this renewed world.
535
00:48:14,883 --> 00:48:16,203
Look at this.
536
00:48:17,843 --> 00:48:19,563
See this impression
in the rock here?
537
00:48:19,563 --> 00:48:24,723
Look, there are one, two,
three toes.
538
00:48:24,723 --> 00:48:27,483
This is a dinosaur footprint,
539
00:48:27,483 --> 00:48:31,123
and I love the fact that
I can put my hand
540
00:48:31,123 --> 00:48:34,123
where a dinosaur once put its foot.
541
00:48:34,123 --> 00:48:37,723
Now, whether dinosaurs existed
before the rains, we can't be sure.
542
00:48:37,723 --> 00:48:41,003
If they did, it was only
as an obscure group
543
00:48:41,003 --> 00:48:42,763
in the south of Pangea.
544
00:48:42,763 --> 00:48:45,403
But in the millions of years
after the rains,
545
00:48:45,403 --> 00:48:46,883
they certainly prospered.
546
00:48:46,883 --> 00:48:53,203
In some places, 90% of the
vertebrate fossils are dinosaurs.
547
00:48:53,203 --> 00:48:55,403
Why did they suddenly do so well?
548
00:48:55,403 --> 00:48:57,043
Well, it could be down to the food.
549
00:48:57,043 --> 00:49:01,163
They could use it more efficiently
to grow bigger more quickly.
550
00:49:01,163 --> 00:49:03,283
But whatever the reason,
551
00:49:03,283 --> 00:49:06,403
dinosaurs went on
to dominate the Earth.
552
00:49:07,483 --> 00:49:08,683
I love this!
553
00:49:15,323 --> 00:49:17,563
By the end of the Triassic,
554
00:49:17,563 --> 00:49:21,763
the stage is set for the reptiles
to rule supreme.
555
00:49:26,083 --> 00:49:32,123
This will be their world
for the next 140 million years.
556
00:49:35,563 --> 00:49:38,643
The age of the dinosaurs is dawning.
557
00:49:51,523 --> 00:49:55,083
In one way,
the End-Permian extinction
558
00:49:55,083 --> 00:49:59,443
exposed the fundamental fragility
of life.
559
00:49:59,443 --> 00:50:02,563
Countless species of plants
and animals were wiped out
560
00:50:02,563 --> 00:50:04,483
by those volcanic eruptions,
561
00:50:04,483 --> 00:50:07,643
and it took millions of years
to recover.
562
00:50:07,643 --> 00:50:11,483
But perhaps the event also taught us
another lesson
563
00:50:11,483 --> 00:50:14,003
about the tenacity of life -
564
00:50:14,003 --> 00:50:18,403
because the living world did
bounce back, to be just as complex
565
00:50:18,403 --> 00:50:22,803
and just as beautiful,
in fact, maybe even more so.
566
00:50:29,523 --> 00:50:33,323
But there's a big
unspoken question here.
567
00:50:33,323 --> 00:50:37,203
For over 100 years, we've been
pumping carbon dioxide into
568
00:50:37,203 --> 00:50:41,803
the atmosphere and watching
as global temperatures creep up.
569
00:50:43,483 --> 00:50:49,923
So, what can the mass extinction
252 million years ago teach us
570
00:50:49,923 --> 00:50:52,883
about our own climate change event?
571
00:50:58,603 --> 00:51:03,403
I think the big lesson we've just
learned is that the living world
572
00:51:03,403 --> 00:51:05,763
will ultimately be fine.
573
00:51:05,763 --> 00:51:09,923
Even if we don't address
our climate and biodiversity crisis,
574
00:51:09,923 --> 00:51:13,603
if we burn every last lump of coal
and drop of oil,
575
00:51:13,603 --> 00:51:17,123
if we leave this place
as a complete hellscape,
576
00:51:17,123 --> 00:51:21,523
whilst we might perish,
life will bounce back,
577
00:51:21,523 --> 00:51:25,683
and this will all be
beautiful again -
578
00:51:25,683 --> 00:51:27,403
which begs the question,
579
00:51:27,403 --> 00:51:31,203
"Should we bother to preserve
and protect it?"
580
00:51:31,203 --> 00:51:35,843
Well, that extinction event
252 million years ago
581
00:51:35,843 --> 00:51:37,923
was part of a planetary process.
582
00:51:37,923 --> 00:51:40,603
It was a chance volcanic eruption.
583
00:51:43,523 --> 00:51:45,443
Think of all of that suffering.
584
00:51:45,443 --> 00:51:47,563
Think of all of that wastage.
585
00:51:50,163 --> 00:51:54,523
Do we want those sorts of
extinctions on our conscience?
586
00:51:56,163 --> 00:51:57,403
I don't think so.
587
00:52:16,523 --> 00:52:21,163
In this episode, we saw how
an Earth-shattering eruption
588
00:52:21,163 --> 00:52:24,443
destroyed almost all life on Earth.
589
00:52:29,283 --> 00:52:32,003
This is the closest
our planet has ever been
590
00:52:32,003 --> 00:52:33,683
to going back to square one.
591
00:52:35,883 --> 00:52:38,043
To understand the scale
of the event,
592
00:52:38,043 --> 00:52:41,603
scientists mapped
the Permian lava fields of Russia -
593
00:52:41,603 --> 00:52:44,643
known as the Siberian Traps.
594
00:52:46,483 --> 00:52:50,243
I have actually been to
the Siberian Traps
595
00:52:50,243 --> 00:52:53,043
and flown helicopters.
596
00:52:54,403 --> 00:52:58,763
The helicopter is right, mm...there.
597
00:52:58,763 --> 00:53:02,803
Floated on boats, hiked,
598
00:53:02,803 --> 00:53:07,563
ridden on trains
all over Arctic Siberia,
599
00:53:07,563 --> 00:53:10,843
looking for remnants of
the Siberian Traps.
600
00:53:12,163 --> 00:53:17,843
And these lava flows go distances
that boggle the mind.
601
00:53:17,843 --> 00:53:23,483
The 1 million cubic miles that we
have is probably a minimum number,
602
00:53:23,483 --> 00:53:26,643
and it's a minimum
because not all of the rocks
603
00:53:26,643 --> 00:53:28,763
are exposed at the surface.
604
00:53:28,763 --> 00:53:32,123
We also sampled the rocks of
the Siberian Traps
605
00:53:32,123 --> 00:53:35,203
with sledgehammers and rock hammers
606
00:53:35,203 --> 00:53:37,003
and a lot of hard work.
607
00:53:39,043 --> 00:53:41,963
The rock samples were key
to understanding
608
00:53:41,963 --> 00:53:45,963
why the Earth's climate
changed so dramatically.
609
00:53:45,963 --> 00:53:49,083
When magma comes up from
deep within the Earth,
610
00:53:49,083 --> 00:53:52,123
it has gases dissolved in it,
611
00:53:52,123 --> 00:53:56,003
gases like carbon dioxide
and sulphur dioxide.
612
00:53:56,003 --> 00:53:59,083
These gases come out into bubbles,
613
00:53:59,083 --> 00:54:03,963
a bit like when you take the lid off
a soda bottle and it fizzes.
614
00:54:03,963 --> 00:54:08,763
But these gases told
a contradictory story.
615
00:54:08,763 --> 00:54:12,323
Sulphur dioxide and carbon dioxide
have opposite effects
616
00:54:12,323 --> 00:54:14,163
on the Earth's atmosphere.
617
00:54:14,163 --> 00:54:17,803
Sulphur dioxide reflects sunlight
back into outer space,
618
00:54:17,803 --> 00:54:19,403
causing global cooling,
619
00:54:19,403 --> 00:54:21,963
whereas carbon dioxide
is a greenhouse gas
620
00:54:21,963 --> 00:54:23,563
and can lead to global warming.
621
00:54:26,003 --> 00:54:29,563
It turns out that different volcanic
gases hang around in our atmosphere
622
00:54:29,563 --> 00:54:31,083
for different amounts of time
623
00:54:31,083 --> 00:54:35,403
because of their different
chemical properties.
624
00:54:35,403 --> 00:54:37,683
Sulphur dioxide tends to stay
in the atmosphere
625
00:54:37,683 --> 00:54:39,883
for a shorter period of time,
626
00:54:39,883 --> 00:54:41,803
because it can get rained out.
627
00:54:42,883 --> 00:54:46,083
But carbon dioxide can stay in
the Earth's atmosphere for hundreds,
628
00:54:46,083 --> 00:54:47,563
if not thousands of years.
629
00:54:49,003 --> 00:54:52,963
Scientists think that
heat-trapping carbon dioxide
630
00:54:52,963 --> 00:54:56,843
would have built up in
the atmosphere, warming the planet.
631
00:54:59,483 --> 00:55:03,763
And there were other clues
in the fossil record.
632
00:55:03,763 --> 00:55:06,523
So, we can measure what
temperatures were like in the past
633
00:55:06,523 --> 00:55:08,243
by the study of fossils,
634
00:55:08,243 --> 00:55:10,563
and particularly
fossil bone material.
635
00:55:10,563 --> 00:55:12,163
So, when the bone is formed,
636
00:55:12,163 --> 00:55:14,683
it's partly controlled
by the temperature.
637
00:55:14,683 --> 00:55:17,163
And so by studying these bones,
we're able to see
638
00:55:17,163 --> 00:55:19,643
what the temperatures were like
back in the past.
639
00:55:23,443 --> 00:55:29,843
Temperature rises of up to 7 degrees
brought a deluge of rainfall.
640
00:55:29,843 --> 00:55:33,163
Known as the Carnian
Pluvial Episode,
641
00:55:33,163 --> 00:55:37,123
some scientists think
these conditions were essential
642
00:55:37,123 --> 00:55:39,323
to the success of the dinosaurs.
643
00:55:40,643 --> 00:55:45,963
My research suggests that more rain
means it's better for the plants.
644
00:55:45,963 --> 00:55:51,363
This era of warm, wet conditions
really boosted plant diversity.
645
00:55:51,363 --> 00:55:54,643
More plants equals more insects,
more plant-eaters,
646
00:55:54,643 --> 00:55:57,323
and then you get more meat-eaters
as well,
647
00:55:57,323 --> 00:55:59,283
and dinosaurs are part
of that growth.
648
00:56:01,683 --> 00:56:03,203
So, this is Herrerasaurus.
649
00:56:03,203 --> 00:56:05,803
This is one of the first dinosaurs
to appear.
650
00:56:05,803 --> 00:56:08,523
And as you can see
by the sharp teeth here,
651
00:56:08,523 --> 00:56:12,283
this was a meat-eater,
one of the top predators.
652
00:56:12,283 --> 00:56:16,803
The evidence for this growth
is written in the rock record.
653
00:56:16,803 --> 00:56:20,123
The success of the dinosaurs
after this event is seen in
654
00:56:20,123 --> 00:56:23,843
just an abundance of their fossils,
but also in their sort of indirect
655
00:56:23,843 --> 00:56:27,643
records that they leave in the forms
of their footprints as well.
656
00:56:27,643 --> 00:56:29,923
Before the Carnian Pluvial Episode,
657
00:56:29,923 --> 00:56:32,963
dinosaurs and their relatives only
made up around 5% of the footprints
658
00:56:32,963 --> 00:56:35,363
at these different fossil sites.
659
00:56:35,363 --> 00:56:38,843
After the Carnian Pluvial Episode,
we see a big increase -
660
00:56:38,843 --> 00:56:40,643
it jumps up to 70%.
661
00:56:42,243 --> 00:56:45,523
The explosion in the population
of dinosaurs
662
00:56:45,523 --> 00:56:48,963
is a brand-new area of research.
663
00:56:48,963 --> 00:56:51,963
We can see that the ecosystems
were changing,
664
00:56:51,963 --> 00:56:54,123
but what actually would've
affected the dinosaurs,
665
00:56:54,123 --> 00:56:56,523
what would've caused them
to be successful,
666
00:56:56,523 --> 00:56:58,323
we don't know yet.
667
00:56:58,323 --> 00:57:00,323
This is why there's
so many palaeontologists
668
00:57:00,323 --> 00:57:02,083
doing active research.
669
00:57:08,523 --> 00:57:09,843
Next time...
670
00:57:13,243 --> 00:57:17,003
..we journey deeper into the past,
671
00:57:17,003 --> 00:57:20,803
to witness one of the strangest
moments in history...
672
00:57:22,683 --> 00:57:25,603
..a global deep freeze..
673
00:57:27,243 --> 00:57:30,163
..that transformed the Earth...
674
00:57:30,163 --> 00:57:32,043
..into an ice world.
675
00:57:37,243 --> 00:57:40,163
If the Earth could talk,
what would it tell us?
676
00:57:40,163 --> 00:57:42,723
Well, the Open University imagine
how it might answer
677
00:57:42,723 --> 00:57:44,203
some of our questions.
678
00:57:44,203 --> 00:57:46,803
To experience
this interactive presentation,
679
00:57:46,803 --> 00:57:49,363
go to the website on the screen
and follow the links
680
00:57:49,363 --> 00:57:51,243
to The Open University.
87541
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