Series in which Professor Iain Stewart looks at how geology has shaped human history. He explores the newest force, humans, whose impact is both positive and negative.
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Our planet has immense power,
and for most of human history it has dominated us.
In the series so far we've seen how the forces of the planet,
the deep Earth,
have all had major impacts on human history.
But now the relationship between us and the planet is changing.
We're no longer at its mercy.
We have now become a major planetary force.
The fundamental elements of our planet have helped shape human history,
but now we ourselves are a force of nature to be reckoned with.
Even in the wildest corners of the Earth,
you can't escape our human influence.
The question is what does that mean for our future?
If you want to get a sense of our changing relationship with the planet,
then this vast expanse of mud is the place to come.
This is no ordinary mud.
The towering column of steam
shows that this mud is emerging from within the Earth at boiling point.
I'm in Indonesia,
one of the most volcanically active countries on Earth.
Which is a clue to the origin of this strange phenomenon.
You know, what's happening down there
is one of the most unusual eruptions on Earth.
It's a volcano, but it's not spewing out molten lava.
That is a mud volcano.
This volcano began erupting in 2006,
and for the people who live here, it's been a disaster.
Around 30,000 people have been displaced by the mudflow,
and around 10,000 homes have been destroyed.
You know, the scale of this is truly enormous,
and all the way around it's surrounded by villages,
and many of them are half flooded with the mud...like that there.
Look at that, completely burying these trees here.
Down on the ground, there's a real sense of desolation.
Up close, it's the sheer oddness of the scene that strikes you most,
like the fact that I'm walking alongside the roof of a mosque,
a mosque that was once the centre piece of a village
that now lies entombed in solid mud beneath me.
Such an eerie feeling.
It's as if the planet has decided to reclaim this place from humanity.
Life has been completely smothered.
But there's something that makes this eruption unique.
And that is what it was caused by.
The eruption going on out there is really special,
because it's almost certain it's not natural at all.
Geologists think it was triggered by us...by human activities,
when an underground probe for natural gas went horribly wrong.
In 2006, developers were drilling in search of gas,
but at around 3,000 metres, they withdrew the drill.
The pressure in the well then dropped,
which sucked in hot water from surrounding rock.
This caused fractures in the rock.
Water burst through and shot upwards
mixing with layers of mudstone
to form a liquid mud that boiled to the surface.
Every day, enough mud emerges
to fill more than 40 Olympic-size swimming pools.
To try to contain the flow, enormous levees have been constructed.
Wallowing machines are still trying to channel mud
away from the surrounding villages.
Concrete blocks have even been thrown into the centre of the volcano
in an attempt to "plug" it.
But every effort to hold back this relentless tide has failed.
To me, this eruption symbolises
our strange relationship with the planet today.
On the one hand, we are an incredibly powerful force now,
capable of triggering volcanic eruptions.
But on the other hand, we're not really in control of that power.
Much of the effect we have on the planet even takes us by surprise.
These days, it's easy to see our impact on the planet
in a negative light - the story of an Eden destroyed.
But our relationship with the Earth
is far more intriguing and surprising than that.
We have a much longer history of
transforming the planet than you might think.
And not all of those changes have been bad news.
To go back to the start of the story,
I'm off to Canada's Rocky Mountains.
This mountain scenery is spectacular,
sculpted by one of the Earth's great cycles,
a cycle that's not only transformed the surface the planet,
but it's also been critically important for our evolution, to our history.
It's the cycle of the ice ages.
For millennia, the Rockies have been a battleground
for immensely powerful geological forces.
Ice has carved this landscape, creating these dramatic peaks
and cutting deep valleys out of the rock.
You know, for the past one million years or so,
our planet's been swinging back and forth between long ice ages -
when mountains like these were embedded deep in the ice -
and much shorter warm periods, like we're in now.
The ice waxed and waned according to small changes in the Earth's orbit,
and that influenced the amount of heat
falling on different parts of the Earth's surface.
The ice age cycle is pretty well understood.
I mean, it's not an exact science,
and there are plenty of complicating factors,
but what it means is that scientists can predict
when ice ages should begin and when they should end.
But until recently, geologists had been missing something.
New data has provided a more accurate understanding
of temperature changes between ice ages -
periods known as interglacials.
The data shows that during past interglacials,
temperatures steadily declined.
If that pattern had continued into the present interglacial,
we would now be heading into a new ice age.
From here you get a good idea of what that would have meant.
If cooling had continued to the present day,
that ice would have crept down and smothered the whole valley.
From about 7,000 years ago,
temperatures would have started to fall.
In Europe, the glaciers of the Alps would have spread out
across alpine meadows.
If the cycle of the ice ages had continued to follow
the same pattern as in the past,
then human history would have followed a very different course.
But it didn't happen.
It was the ice age that never was.
If you like, a great escape.
So what prevented the ice from following the same rhythms
that it always followed in the past?
There's a clue in the timing.
Just when it should have been getting cooler,
a major change to the planet was under way.
It's thought that farming began around 11,000 years ago
in the Middle East, in what's known as the Fertile Crescent.
It took a while to catch on, but by 7,000 years ago
it was spreading fast, across Europe and Asia.
Even though our numbers were still small,
farming had a big impact on the planet.
Fires were used to clear the forests for farmland,
which increased the amount of carbon dioxide in the atmosphere.
We domesticated wild animals, which produce a lot of methane.
Both carbon dioxide and methane are powerful greenhouse gases.
This new theory suggests that the gentle rise in greenhouse gases
meant that instead of temperatures falling, as they had in the past,
they stayed steady.
The rise of farming was enough to halt the onset of the next ice age.
It's fascinating to think that as far back as 7,000 years ago
we had already made an impact on the planet at a global scale.
This was the beginning of our role as a force of planetary change.
Since then, human progress has been defined by our ability
to find ever more inventive ways
of exploiting the planet's natural systems.
Around 5,000 years ago, our ancestors discovered
that trapped within certain types of rock were metal ores.
These mineral-rich rocks were formed deep inside the Earth
over millions of years.
The metals they released could be transformed into tools,
the foundation of civilisation.
By 2,000 years ago,
people had found ingenious ways to intercept the water cycle.
They tapped fresh water underneath deserts
and used it to create some of the first cities.
Around 500 years ago,
sailors learnt how to exploit the power of the Earth's wind systems.
They used them to develop global ocean trade routes.
And more recently, we discovered that the fossilised remains
of plants and animals, coal and oil,
could become major sources of energy.
Each of these discoveries was a landmark
in our ability to use planetary systems for our own purposes.
Today, the way in which
we use the Earth's resources can be summed up by this...
It's just great to be able to get up close
to one of these beautiful machines. They're so elegant and streamlined.
A kind of fusion of precision engineering and raw power.
It's absolutely beautiful.
But as a geologist, I can't help seeing these planes
through a different lens.
Just look at what goes into making one...
Aluminium, or aluminum, comes from a mineral called bauxite.
It's the most abundant metallic element in the Earth's crust,
which has been concentrated within rock over millions of years.
Perspex - in its most basic form, oil.
It's made inside the Earth over hundreds of thousands of years
from dead organic matter.
And the wiring, loads of copper from a mineral like malachite.
Anyway, you get the picture. This thing comes from the Earth.
In many ways, it feels like modern life is detached from the planet,
but actually we're linked to it
in hundreds of subtle and surprising ways.
This plane is a huge conglomeration of natural resources
that have all been precisely extracted, transformed, moulded
and connected by us.
And what's staggering is the scale on which we do this.
This airbase in the Arizona desert is home to over 4,000 planes.
Many of them will never fly again.
Effectively, this is a vast accumulation
of the planet's minerals.
Our impact on the planet is felt not just in what we transform,
but also in what that transformation leaves behind.
I've come here because rivers carry and deposit sediment.
This is what forms the rocks of the future.
The old geological hammer's not much use here. Urgh!
You know, there's a lot of things in here that I would expect.
There's lots of plant remains, some pollen grains.
I see a few snail shells.
But in amongst all that
there's some very odd little fragments,
like, a-ha, just here.
Now that...looks like a little shell, but it's not.
It's made of plastic...
and what that is is a little plastic pellet,
the kind of plastic pellets that go into making plastic bags, plastic bottles.
There's more of them, there's loads of them, there's another one.
And look at that, it's a plastic seal of a bottle.
Now, that may not be so surprising
when you consider exactly where this river is...
I'm right in the centre of Los Angeles,
home to around four million people and all that goes with them.
But the impact of plastics reaches much further than major cities.
Globally, around 26 million tonnes of plastic
ends up in the ocean every year,
where it becomes part of something much bigger.
In the Pacific Ocean, plastic from America
is swept into a large revolving ocean current known as a gyre.
As this current circulates, it also picks up material from East Asia.
Over time, these plastics accumulate in enormous flotillas.
One of them is so big it's even got its own name -
the Eastern Pacific Garbage Patch.
Eventually, the plastic is broken down by the sun's ultraviolet rays
into smaller particles,
that sink to the sea floor, where they are buried.
It's the first stage in their transformation into sedimentary rock.
The Grand Canyon is a striking example
of the scale this process operates on.
These cliffs were once an ancient seabed,
formed over millions of years, as layer after layer of sediment built up.
Under immense pressure, these layers were cemented together
to form the rock strata we see today.
The plastics that lie at the bottom of the ocean
will eventually form part of the rocks of the future -
our geological legacy.
You know, it's a sobering thought that from the planet's point of view,
our enduring signature, the thing that marks out the modern human age
in geological terms, will be the dead weight
of millions of tonnes of different kinds of plastics.
Our ability to take the Earth's resources
and transform and deposit them in vast quantities
means we've now made an indelible mark
in the planet's 4.5 billion-year history.
We can slice the tops off mountains
and dig holes big enough to bury a city.
In a single year, we now move more earth and rock
than all the natural processes of erosion put together.
Our machines have transformed the planet.
So great is our impact on the Earth that it has been used
to define a new geological epoch...
..the Anthropocene, the human epoch.
If you add together all the landscapes we've altered -
our cities, towns, villages and farmland -
then 75% of the Earth's ice-free landmass owes its appearance to us.
This truly is a human planet.
Sometimes our intervention in the planet's natural processes
can have surprising and far-reaching consequences.
This is South Dakota in the United States.
It's hard to believe it, but this was once a busy little town,
up to 300 people living here in its heyday.
It's hard to imagine it as a jostling little farming community,
but that's exactly what it was.
In the early 1900s, this was a boom town.
Farmers poured into the Great Plains of the western USA
to develop new land.
You'd think this place would be fantastic for farming.
The whole landscape is covered in a thick blanket of silts and clays,
blown or washed in after the last ice age.
Soil is a mixture of minerals from broken-down rocks
and nutrients from organic matter.
It takes more than 500 years to create just 2cm of it.
What keeps that fine sediment here is the vegetation -
the grasses bind the topsoil together.
But the first settlers ploughed over those grasses
and exposed the delicate soil underneath, and that dried out in the sun.
When the rains failed in the 1930s, the ploughed-up soil was exposed
to the full force of the wind.
The result was devastating.
It became known as the Dust Bowl.
Half a million people in the Great Plains were made homeless.
100 million acres of farmland turned to wasteland.
The homesteaders of the Great Plains had upset
the delicate balance of the landscape.
80 years on, that delicate balance is one we still find hard to keep.
In China, deforestation and overgrazing
means soils are being degraded 30 times faster
than the planet's natural processes can replenish them.
In Australia, clearing large areas of bush for farmland
has allowed salt to infiltrate the topsoil,
damaging around 60,000 square kilometres.
In total, 25% of the world's farmland has now been degraded
as an inadvertent consequence of our drive to increase food production.
There's now an extraordinary contrast
between the Earth's natural environments
and the ones that we've created.
To fully appreciate the extent
of our interference in the planet's natural processes,
take a look at one of the Earth's most fundamental cycles...
...the water cycle.
Rain that falls over mountains makes its way into streams and rivers.
This is the Lena River.
Its headwaters are in the Baikal Mountains,
where rain and snowmelt set the cycle going.
It travels 4,500 kilometres across Siberia...
...before it reaches a huge delta,
on the edge of the Arctic Ocean.
Here it returns water to the sea, which evaporates to form clouds,
and the cycle begins again.
The Lena is one of the few major rivers
that still completes the water cycle from source to sea
without a single man-made interruption.
Today, we've created an alternative water cycle.
This is part of the Colorado River system.
Along its 2,000-kilometre length, it has over 20 dams.
So much water is diverted to the cities and farmland
of the American West that most years,
it no longer reaches the sea.
The biggest city it supplies is Los Angeles.
Fresh water is delivered across hundreds of kilometres of desert
via a network of aqueducts, canals and pipelines.
This system delivers 90% of the city's fresh water.
Without it, LA wouldn't exist.
The veins and arteries of our water supply
are the lifeblood of our civilisation.
And the human version of this planetary cycle
operates at a global scale.
We have altered the planet's water cycle to such an extent
that five times as much fresh water is stored in reservoirs
as flows in all the world's rivers.
This change in the balance of power between us and the planet is based
more than anything on our ability to exploit one particular resource.
This is the Athabasca River, in the heart of Alberta in Canada.
It doesn't look like it, but today this is a fresh frontier
in one of the great geological quests of our age -
the hunt for oil.
Oil is central to our lives.
It fuels a mechanised world.
It's a concentrated form of energy, easily transported.
Every year we burn around 31 billion barrels of it -
that's 1,000 barrels a second.
The problem is... it won't last forever.
The amount of oil we're burning each year takes the planet
over three million years to make.
Finding more oil is getting harder.
Some say we've already reached a peak in oil production,
and that from now on it's all downhill,
with supply unable to keep pace with demand.
But others say that's a load of rubbish -
there's plenty of oil in the ground, it's just a case of finding it.
For those in the second camp, one of their prime exhibits is here.
Ah, now, this is what I've come to find. Look at this.
Looks like the rock's bleeding, doesn't it?
This place is just full of oil...
coming out of the rock, and if you look at it, the thing is...
Look at that - ugh!
You feel as if, if you just squeeze it, it would come out.
It's actually a sand, but all the sand grains are just coated in oil.
We've got a name for this - we call it tar sands -
and this is just about the dirtiest oil around.
The whole cliff is just full of it.
This kind of oil doesn't come shooting out in a great fountain.
And you don't get at it by drilling down into the ground.
This is a very different type of oilfield.
To appreciate just how different it is, you have to go up high.
Oh, my... Look at that! It's like we've gone into a different world.
This oil deposit is thought to contain
almost a trillion barrels of oil.
It covers 50,000 square kilometres.
I mean, look at that. The forest just ends there,
and then after that, just industry for miles upon miles.
To get at the tar sands involves scraping the surface
off vast tracts of land.
This is strip mining for oil.
Right below me, you can see both the huge attraction of tar sands
and their Achilles heel.
On the one hand, there's just vast amounts of oil -
those fields seem to go on and on forever.
But on the other hand, getting it out comes at a price,
a hell of a price.
Although it's at the surface, it's much harder to extract
than conventional oil.
To separate the oil from the sand,
huge volumes of steam have to be injected into it,
and that's expensive.
In a traditional oil well, you'd expect around 25 barrels of oil back
for every one barrel of energy you use to extract it.
Here, it's more like one barrel of energy in
and only five barrels back.
You know, tar sands may be messy,
but we still get more energy out of them than we put in.
So as far as oil's concerned, they're one of our best prospects.
But it's not exactly an appealing image of hope, is it?
Can't help but think...
that we really are scraping the bottom of the barrel.
The tar sands illustrate that the oil is still out there.
And new sources are being discovered.
It's just they tend to be exceptionally hard to reach.
For centuries, our ingenuity has enabled us to find new forms of energy,
so it's easy to think that trend will continue.
History tells us that we don't tend to run out of resources.
Instead, when push comes to shove, we find new ones.
But that is a lesson from human history.
The planet's history has perhaps a more important lesson for us.
It's a lesson about the most dramatic human influence on the planet -
the speed and scale at which we're changing the atmosphere.
Levels of carbon dioxide and methane are higher than at any time
in the last 15 million years.
We can already see some of the effects.
The thickness of the Arctic sea ice has almost halved.
Some of the extra carbon dioxide we've pumped into the atmosphere
has been absorbed by the oceans.
This has increased their acidity by 30%,
hindering the growth of marine creatures, like corals.
Over the last few decades,
the frequency of extreme hurricanes has doubled in some areas.
We're at the beginning of a dramatic period of change.
At the heart of it is the greenhouse effect,
a global warming caused by the gases we release.
The question is, how will the planet - and our civilisation -
respond to this change?
For me, the best way to answer this question is to look back
into the Earth's past.
Which is why I've come to the coast of California.
There's something really strange going on in the ocean over here -
the whole water looks as if it's fizzing away like mad.
I've never known anything like it.
This promises to be an unusual dive.
The point is to take me back to the last time
the Earth experienced a rapid and extreme increase in greenhouse gases.
it's like swimming in champagne.
Everywhere you look,
wherever you are, you're surrounded with bubbles.
These bubbles are the key to unlocking one of the Earth's great events.
55 million years ago, the atmosphere went through something very similar
to the changes happening today.
The bubbles are full of a gas called methane,
which is leaking out of a fault line deep below me
and heading up there to the atmosphere.
And it's this speed and intensity of bubble release that's a critical factor.
Today, only relatively small amounts of methane bubble out
from seeps like this at the bottom of the ocean.
But 55 million years ago,
methane started to erupt from the ocean in massive quantities.
No-one is quite sure why it happened,
but huge areas of the ocean would have been bubbling like this.
55 million years ago,
these bubbles wouldn't have been fizzing out,
they would have been belching out. It would have had a devastating effect.
Methane is 20 times more potent than carbon dioxide as a greenhouse gas.
And as it burst up through those ancient oceans,
it led to sudden, runaway global warming.
That burst in methane levels 55 million years ago
was the closest experience we've got
of what continued global warming might bring.
So what was it that happened to the planet
during that ancient surge in global warming?
And what did it mean for life?
The answer can be found
nearly 8,000 kilometres away, on the Svalbard archipelago.
It's well within the Arctic Circle.
60% of Svalbard is covered in glaciers.
It's a landscape dominated by ice.
But 55 million years ago, it was rather different.
The clues are in the rocks.
Let's see what we've got. Ooh!
Ooh, look at this.
It's what I was hoping to find.
These rocks are stacked full of ancient leaves.
Look, there's a frond of a plant there.
There's another one here. There's a stem with branches going out.
These rocks are packed full... of leaves.
Better keep going.
Look at this! Would you believe it?!
These fossil leaves originate
from a time just after the methane surge in the oceans.
They're from a distant relative of the beech,
a broad-leafed deciduous tree.
Some of these trees are preserved
in the permafrost in other parts of the Arctic.
You can just imagine these falling down from trees onto an ancient forest floor.
But, I mean, today...
you don't get trees here. You don't get trees like this for hundreds of miles.
It just tells you that 55 million years ago,
Svalbard was a very different place.
Following the methane surge in the ocean,
global temperatures would have been 10 degrees warmer than they are today.
It caused immense upheaval.
Plants and animals were forced to migrate towards the poles.
Back then, I would have been walking through
a completely different landscape - subtropical swamps and forest.
Less High Arctic - more Florida Everglades.
It would have been inhabited by ancestors of creatures
like the hippopotamus and the crocodile.
The lesson from the Earth's past
is that the world we know today can change out of all recognition,
simply by raising the level of greenhouse gases in the atmosphere.
But the remarkable events of 55 million years ago
offer another, more optimistic, lesson for us.
Clearly this extraordinary warm period 55 million years ago didn't last -
otherwise, I wouldn't be dressed like this.
The planet cooled, ice came to the Arctic.
So what happened?
What happened was the Himalayas.
The creation of this mountain range helped return ice to the Arctic.
When the tectonic plates of India and Eurasia collided
around 50 million years ago,
the result was a mountain range that grew to become the biggest on Earth.
In building the Himalayas, the planet unleashed
its most formidable global-cooling weapon...
The process begins when carbon dioxide in the atmosphere
is dissolved in rain and snow.
This reacts with minerals in the rock
to form a solution that's carried by rivers to the sea.
Here, the carbon is absorbed by marine creatures.
When these die, they sink to the sea floor,
eventually becoming rock, locking the carbon away.
Because the Himalayas were constantly rising,
they were perpetually exposing new rock to the elements.
This drew more carbon dioxide out of the atmosphere,
cooling the planet
and eventually leading to the re-freezing of the Arctic.
So the planet had an entirely natural way
of reducing greenhouse gases.
But there's one obvious problem, and that is
it takes millions of years to build a mountain range,
and we don't have the luxury of that sort of time.
Yet the lesson from history is not entirely wasted.
Burying carbon has long been the sole preserve of the planet,
but there's no reason why we can't have a go at doing the same thing ourselves.
We are now developing ways to take carbon out of the atmosphere.
One method is to stimulate the growth of immense blooms of algae
that use photosynthesis to draw carbon dioxide from the atmosphere.
On land, there are plans
to create artificial trees that replicate photosynthesis.
But the biggest challenge
is to stop carbon dioxide reaching the atmosphere in the first place.
This can be done by capturing it at source,
filtering it from industrial chimneys
and then burying it.
Scientists are planning to try this out on Svalbard.
If you happen to have thousands of tonnes of carbon to dispose of,
the geology here is particularly helpful.
That cliff behind me is a layer cake of sandstone and shale.
And that arrangement is perfect for burying carbon.
This sandstone is ideal for storing the carbon,
because there's lots of spaces in the pores between the grains.
And this dense, impermeable shale provides the ideal lid
that stops the carbon escaping upwards.
The plan is to drill a number of shafts through the dense shale lid
and into the sandstone.
Carbon dioxide will then be pumped down into the sandstone,
where it will be locked within the pores of the rock.
Carbon capture won't solve our greenhouse gas problem,
but it might at least buy us some time to develop cleaner forms of energy.
Burying and locking away carbon is an attempt to accelerate massively
what the Earth has done for millions of years.
It's the beginning of a new approach to the planet,
deliberately transforming it
to try and preserve the conditions for our survival.
Up until now, the effects of our impact on the planet, whether good or bad,
have been accidental and unintended.
Whether it's a mud volcano in Indonesia or altering the Earth's climate,
we never set out to create these changes.
Science has given us an understanding of how the planet works
that allows us to protect ourselves against Earth's unpredictable nature.
But today, we're on the brink of a new era.
We can now take control of our impact on the planet's natural processes
and maintain the conditions for civilisation to flourish.
It's a big challenge, which involves global co-operation.
But there's an example of what can be achieved here in Svarlbad.
You know, you'd never know it,
but locked inside this mountain is something incredibly precious.
And that...that's the way in.
It's got a front door!
It looks like something out of James Bond!
To protect its contents, this facility in Svalbard has been built high enough
to be above any future rise in sea level.
It's been excavated so deep into the mountain
that it would survive a nuclear explosion.
This is apocalypse planning for our future survival.
You know, this is a giant vault,
but in a way it's the modern equivalent of a Noah's ark,
except that instead of sheltering animals,
it's preserving the future of the world's food supply.
The temperature is a constant minus 18 degrees Celsius
to protect the precious contents stored here.
This is a shrine to over 10,000 years of agricultural development.
It's a global seed vault.
I mean, take this -
this is rice. But the thing is,
there's not just one variety of rice in here, there's thousands,
with different properties and different growing conditions,
different resistance to disease.
This is the genetic diversity of rice for the future.
But of course it's not just about rice.
This vault will one day store
every variation of every staple crop from every country on the planet.
It's a heck of an insurance policy.
You know, for me, preserving these seeds,
with all their precious genetic code, makes a really important point.
And that is, we're taking conscious control over an uncertain world.
And in that sense, this whole place is like a symbol
of what can be achieved at a global level,
if we put our minds to it.
In this series, we've seen how the fate of past civilisations
has been shaped by the planet's natural forces.
The Khmers of Angkor Wat thrived on their ability to exploit the monsoon
until their growing population
outstripped their most precious resource - water.
The Anasazi of Chaco Canyon came to ruin
when a change in the El Nino cycle led to a sudden, prolonged drought.
The Minoans of Santorini flourished
in blissful ignorance of the volcano beneath them
that would one day would destroy their civilisation.
Today, our relationship with the planet is a different one.
We are now a geological force to rival the Earth's natural forces.
The ultimate test will be how well we use that power.
As a species, we like to think that we're special.
Well, this is our chance to prove it.
Professor Iain Stewart explores the most recently established force - humans. It's easy to think of the human impact on the planet as a negative one, but as Iain discovers, this isn't always the case. It is clear that humans have unprecedented control over many of the planet's geological cycles. The question is, how will the human race use this power?