0:00:16 > 0:00:20Our planet has immense power,
0:00:20 > 0:00:25and for most of human history it has dominated us.
0:00:30 > 0:00:34In the series so far we've seen how the forces of the planet,
0:00:34 > 0:00:37the deep Earth,
0:00:37 > 0:00:38wind...
0:00:39 > 0:00:41..fire...
0:00:42 > 0:00:45..and water
0:00:45 > 0:00:49have all had major impacts on human history.
0:00:51 > 0:00:57But now the relationship between us and the planet is changing.
0:00:58 > 0:01:00We're no longer at its mercy.
0:01:00 > 0:01:04We have now become a major planetary force.
0:01:06 > 0:01:10The fundamental elements of our planet have helped shape human history,
0:01:10 > 0:01:15but now we ourselves are a force of nature to be reckoned with.
0:01:17 > 0:01:20Even in the wildest corners of the Earth,
0:01:20 > 0:01:23you can't escape our human influence.
0:01:23 > 0:01:27The question is what does that mean for our future?
0:02:02 > 0:02:06If you want to get a sense of our changing relationship with the planet,
0:02:06 > 0:02:10then this vast expanse of mud is the place to come.
0:02:16 > 0:02:20This is no ordinary mud.
0:02:20 > 0:02:22The towering column of steam
0:02:22 > 0:02:27shows that this mud is emerging from within the Earth at boiling point.
0:02:32 > 0:02:34I'm in Indonesia,
0:02:34 > 0:02:37one of the most volcanically active countries on Earth.
0:02:39 > 0:02:43Which is a clue to the origin of this strange phenomenon.
0:02:43 > 0:02:45You know, what's happening down there
0:02:45 > 0:02:48is one of the most unusual eruptions on Earth.
0:02:49 > 0:02:54It's a volcano, but it's not spewing out molten lava.
0:02:54 > 0:02:57That is a mud volcano.
0:03:03 > 0:03:06This volcano began erupting in 2006,
0:03:06 > 0:03:11and for the people who live here, it's been a disaster.
0:03:13 > 0:03:18Around 30,000 people have been displaced by the mudflow,
0:03:18 > 0:03:21and around 10,000 homes have been destroyed.
0:03:26 > 0:03:29You know, the scale of this is truly enormous,
0:03:29 > 0:03:32and all the way around it's surrounded by villages,
0:03:32 > 0:03:37and many of them are half flooded with the mud...like that there.
0:03:42 > 0:03:45Look at that, completely burying these trees here.
0:03:59 > 0:04:03Down on the ground, there's a real sense of desolation.
0:04:18 > 0:04:23Up close, it's the sheer oddness of the scene that strikes you most,
0:04:23 > 0:04:28like the fact that I'm walking alongside the roof of a mosque,
0:04:28 > 0:04:31a mosque that was once the centre piece of a village
0:04:31 > 0:04:33that now lies entombed in solid mud beneath me.
0:04:33 > 0:04:37Such an eerie feeling.
0:04:43 > 0:04:48It's as if the planet has decided to reclaim this place from humanity.
0:04:51 > 0:04:54Life has been completely smothered.
0:04:57 > 0:05:02But there's something that makes this eruption unique.
0:05:02 > 0:05:04And that is what it was caused by.
0:05:06 > 0:05:09The eruption going on out there is really special,
0:05:09 > 0:05:13because it's almost certain it's not natural at all.
0:05:13 > 0:05:18Geologists think it was triggered by us...by human activities,
0:05:18 > 0:05:23when an underground probe for natural gas went horribly wrong.
0:05:27 > 0:05:31In 2006, developers were drilling in search of gas,
0:05:31 > 0:05:36but at around 3,000 metres, they withdrew the drill.
0:05:36 > 0:05:38The pressure in the well then dropped,
0:05:38 > 0:05:42which sucked in hot water from surrounding rock.
0:05:45 > 0:05:47This caused fractures in the rock.
0:05:47 > 0:05:50Water burst through and shot upwards
0:05:50 > 0:05:53mixing with layers of mudstone
0:05:53 > 0:05:56to form a liquid mud that boiled to the surface.
0:06:05 > 0:06:07Every day, enough mud emerges
0:06:07 > 0:06:11to fill more than 40 Olympic-size swimming pools.
0:06:18 > 0:06:23To try to contain the flow, enormous levees have been constructed.
0:06:23 > 0:06:27Wallowing machines are still trying to channel mud
0:06:27 > 0:06:30away from the surrounding villages.
0:06:32 > 0:06:36Concrete blocks have even been thrown into the centre of the volcano
0:06:36 > 0:06:38in an attempt to "plug" it.
0:06:39 > 0:06:44But every effort to hold back this relentless tide has failed.
0:06:46 > 0:06:49To me, this eruption symbolises
0:06:49 > 0:06:51our strange relationship with the planet today.
0:06:51 > 0:06:56On the one hand, we are an incredibly powerful force now,
0:06:56 > 0:06:59capable of triggering volcanic eruptions.
0:06:59 > 0:07:03But on the other hand, we're not really in control of that power.
0:07:03 > 0:07:08Much of the effect we have on the planet even takes us by surprise.
0:07:13 > 0:07:17These days, it's easy to see our impact on the planet
0:07:17 > 0:07:21in a negative light - the story of an Eden destroyed.
0:07:22 > 0:07:25But our relationship with the Earth
0:07:25 > 0:07:29is far more intriguing and surprising than that.
0:07:29 > 0:07:31We have a much longer history of
0:07:31 > 0:07:34transforming the planet than you might think.
0:07:34 > 0:07:38And not all of those changes have been bad news.
0:07:41 > 0:07:44To go back to the start of the story,
0:07:44 > 0:07:47I'm off to Canada's Rocky Mountains.
0:08:20 > 0:08:23This mountain scenery is spectacular,
0:08:23 > 0:08:26sculpted by one of the Earth's great cycles,
0:08:26 > 0:08:31a cycle that's not only transformed the surface the planet,
0:08:31 > 0:08:36but it's also been critically important for our evolution, to our history.
0:08:36 > 0:08:39It's the cycle of the ice ages.
0:08:47 > 0:08:49For millennia, the Rockies have been a battleground
0:08:49 > 0:08:53for immensely powerful geological forces.
0:08:53 > 0:08:58Ice has carved this landscape, creating these dramatic peaks
0:08:58 > 0:09:01and cutting deep valleys out of the rock.
0:09:01 > 0:09:04You know, for the past one million years or so,
0:09:04 > 0:09:09our planet's been swinging back and forth between long ice ages -
0:09:09 > 0:09:12when mountains like these were embedded deep in the ice -
0:09:12 > 0:09:15and much shorter warm periods, like we're in now.
0:09:19 > 0:09:23The ice waxed and waned according to small changes in the Earth's orbit,
0:09:23 > 0:09:25and that influenced the amount of heat
0:09:25 > 0:09:28falling on different parts of the Earth's surface.
0:09:36 > 0:09:39The ice age cycle is pretty well understood.
0:09:39 > 0:09:41I mean, it's not an exact science,
0:09:41 > 0:09:43and there are plenty of complicating factors,
0:09:43 > 0:09:46but what it means is that scientists can predict
0:09:46 > 0:09:50when ice ages should begin and when they should end.
0:09:52 > 0:09:56But until recently, geologists had been missing something.
0:09:58 > 0:10:01New data has provided a more accurate understanding
0:10:01 > 0:10:04of temperature changes between ice ages -
0:10:04 > 0:10:07periods known as interglacials.
0:10:09 > 0:10:13The data shows that during past interglacials,
0:10:13 > 0:10:16temperatures steadily declined.
0:10:16 > 0:10:20If that pattern had continued into the present interglacial,
0:10:20 > 0:10:23we would now be heading into a new ice age.
0:10:28 > 0:10:32From here you get a good idea of what that would have meant.
0:10:32 > 0:10:35If cooling had continued to the present day,
0:10:35 > 0:10:39that ice would have crept down and smothered the whole valley.
0:10:43 > 0:10:46From about 7,000 years ago,
0:10:46 > 0:10:50temperatures would have started to fall.
0:10:50 > 0:10:53In Europe, the glaciers of the Alps would have spread out
0:10:53 > 0:10:56across alpine meadows.
0:10:56 > 0:10:59If the cycle of the ice ages had continued to follow
0:10:59 > 0:11:02the same pattern as in the past,
0:11:02 > 0:11:06then human history would have followed a very different course.
0:11:15 > 0:11:17But it didn't happen.
0:11:17 > 0:11:19It was the ice age that never was.
0:11:19 > 0:11:21If you like, a great escape.
0:11:21 > 0:11:25So what prevented the ice from following the same rhythms
0:11:25 > 0:11:27that it always followed in the past?
0:11:31 > 0:11:33There's a clue in the timing.
0:11:33 > 0:11:36Just when it should have been getting cooler,
0:11:36 > 0:11:40a major change to the planet was under way.
0:11:44 > 0:11:46Farming.
0:11:48 > 0:11:51It's thought that farming began around 11,000 years ago
0:11:51 > 0:11:55in the Middle East, in what's known as the Fertile Crescent.
0:11:58 > 0:12:02It took a while to catch on, but by 7,000 years ago
0:12:02 > 0:12:05it was spreading fast, across Europe and Asia.
0:12:10 > 0:12:13Even though our numbers were still small,
0:12:13 > 0:12:16farming had a big impact on the planet.
0:12:18 > 0:12:21Fires were used to clear the forests for farmland,
0:12:21 > 0:12:27which increased the amount of carbon dioxide in the atmosphere.
0:12:27 > 0:12:31We domesticated wild animals, which produce a lot of methane.
0:12:33 > 0:12:39Both carbon dioxide and methane are powerful greenhouse gases.
0:12:41 > 0:12:46This new theory suggests that the gentle rise in greenhouse gases
0:12:46 > 0:12:50meant that instead of temperatures falling, as they had in the past,
0:12:50 > 0:12:52they stayed steady.
0:12:53 > 0:13:00The rise of farming was enough to halt the onset of the next ice age.
0:13:12 > 0:13:17It's fascinating to think that as far back as 7,000 years ago
0:13:17 > 0:13:22we had already made an impact on the planet at a global scale.
0:13:22 > 0:13:27This was the beginning of our role as a force of planetary change.
0:13:37 > 0:13:41Since then, human progress has been defined by our ability
0:13:41 > 0:13:43to find ever more inventive ways
0:13:43 > 0:13:46of exploiting the planet's natural systems.
0:13:50 > 0:13:54Around 5,000 years ago, our ancestors discovered
0:13:54 > 0:13:58that trapped within certain types of rock were metal ores.
0:14:00 > 0:14:04These mineral-rich rocks were formed deep inside the Earth
0:14:04 > 0:14:07over millions of years.
0:14:07 > 0:14:11The metals they released could be transformed into tools,
0:14:11 > 0:14:13the foundation of civilisation.
0:14:17 > 0:14:19By 2,000 years ago,
0:14:19 > 0:14:24people had found ingenious ways to intercept the water cycle.
0:14:24 > 0:14:27They tapped fresh water underneath deserts
0:14:27 > 0:14:30and used it to create some of the first cities.
0:14:35 > 0:14:37Around 500 years ago,
0:14:37 > 0:14:42sailors learnt how to exploit the power of the Earth's wind systems.
0:14:43 > 0:14:47They used them to develop global ocean trade routes.
0:14:53 > 0:14:56And more recently, we discovered that the fossilised remains
0:14:56 > 0:15:00of plants and animals, coal and oil,
0:15:00 > 0:15:02could become major sources of energy.
0:15:11 > 0:15:14Each of these discoveries was a landmark
0:15:14 > 0:15:20in our ability to use planetary systems for our own purposes.
0:15:36 > 0:15:37Today, the way in which
0:15:37 > 0:15:41we use the Earth's resources can be summed up by this...
0:15:50 > 0:15:52It's just great to be able to get up close
0:15:52 > 0:15:57to one of these beautiful machines. They're so elegant and streamlined.
0:15:57 > 0:16:01A kind of fusion of precision engineering and raw power.
0:16:01 > 0:16:03It's absolutely beautiful.
0:16:08 > 0:16:12But as a geologist, I can't help seeing these planes
0:16:12 > 0:16:14through a different lens.
0:16:15 > 0:16:18Just look at what goes into making one...
0:16:20 > 0:16:24Aluminium, or aluminum, comes from a mineral called bauxite.
0:16:27 > 0:16:31It's the most abundant metallic element in the Earth's crust,
0:16:31 > 0:16:35which has been concentrated within rock over millions of years.
0:16:37 > 0:16:42Perspex - in its most basic form, oil.
0:16:42 > 0:16:46It's made inside the Earth over hundreds of thousands of years
0:16:46 > 0:16:49from dead organic matter.
0:16:49 > 0:16:53And the wiring, loads of copper from a mineral like malachite.
0:17:00 > 0:17:04Anyway, you get the picture. This thing comes from the Earth.
0:17:10 > 0:17:14In many ways, it feels like modern life is detached from the planet,
0:17:14 > 0:17:17but actually we're linked to it
0:17:17 > 0:17:20in hundreds of subtle and surprising ways.
0:17:20 > 0:17:25This plane is a huge conglomeration of natural resources
0:17:25 > 0:17:30that have all been precisely extracted, transformed, moulded
0:17:30 > 0:17:32and connected by us.
0:17:33 > 0:17:38And what's staggering is the scale on which we do this.
0:17:38 > 0:17:43This airbase in the Arizona desert is home to over 4,000 planes.
0:17:43 > 0:17:45Many of them will never fly again.
0:17:49 > 0:17:52Effectively, this is a vast accumulation
0:17:52 > 0:17:54of the planet's minerals.
0:18:15 > 0:18:19Our impact on the planet is felt not just in what we transform,
0:18:19 > 0:18:25but also in what that transformation leaves behind.
0:18:25 > 0:18:29I've come here because rivers carry and deposit sediment.
0:18:29 > 0:18:32This is what forms the rocks of the future.
0:18:37 > 0:18:41The old geological hammer's not much use here. Urgh!
0:18:45 > 0:18:47You know, there's a lot of things in here that I would expect.
0:18:47 > 0:18:50There's lots of plant remains, some pollen grains.
0:18:50 > 0:18:53I see a few snail shells.
0:18:53 > 0:18:55But in amongst all that
0:18:55 > 0:18:59there's some very odd little fragments,
0:18:59 > 0:19:00like, a-ha, just here.
0:19:02 > 0:19:06Now that...looks like a little shell, but it's not.
0:19:06 > 0:19:09It's made of plastic...
0:19:09 > 0:19:12and what that is is a little plastic pellet,
0:19:12 > 0:19:16the kind of plastic pellets that go into making plastic bags, plastic bottles.
0:19:16 > 0:19:20There's more of them, there's loads of them, there's another one.
0:19:20 > 0:19:24And look at that, it's a plastic seal of a bottle.
0:19:26 > 0:19:28Now, that may not be so surprising
0:19:28 > 0:19:31when you consider exactly where this river is...
0:19:33 > 0:19:36I'm right in the centre of Los Angeles,
0:19:36 > 0:19:41home to around four million people and all that goes with them.
0:19:43 > 0:19:48But the impact of plastics reaches much further than major cities.
0:19:49 > 0:19:53Globally, around 26 million tonnes of plastic
0:19:53 > 0:19:56ends up in the ocean every year,
0:19:56 > 0:20:00where it becomes part of something much bigger.
0:20:06 > 0:20:09In the Pacific Ocean, plastic from America
0:20:09 > 0:20:14is swept into a large revolving ocean current known as a gyre.
0:20:14 > 0:20:20As this current circulates, it also picks up material from East Asia.
0:20:22 > 0:20:27Over time, these plastics accumulate in enormous flotillas.
0:20:29 > 0:20:33One of them is so big it's even got its own name -
0:20:35 > 0:20:39the Eastern Pacific Garbage Patch.
0:20:43 > 0:20:48Eventually, the plastic is broken down by the sun's ultraviolet rays
0:20:48 > 0:20:50into smaller particles,
0:20:50 > 0:20:54that sink to the sea floor, where they are buried.
0:20:56 > 0:21:01It's the first stage in their transformation into sedimentary rock.
0:21:10 > 0:21:13The Grand Canyon is a striking example
0:21:13 > 0:21:16of the scale this process operates on.
0:21:19 > 0:21:23These cliffs were once an ancient seabed,
0:21:23 > 0:21:28formed over millions of years, as layer after layer of sediment built up.
0:21:29 > 0:21:34Under immense pressure, these layers were cemented together
0:21:34 > 0:21:37to form the rock strata we see today.
0:21:40 > 0:21:44The plastics that lie at the bottom of the ocean
0:21:44 > 0:21:48will eventually form part of the rocks of the future -
0:21:48 > 0:21:51our geological legacy.
0:21:56 > 0:21:59You know, it's a sobering thought that from the planet's point of view,
0:21:59 > 0:22:03our enduring signature, the thing that marks out the modern human age
0:22:03 > 0:22:06in geological terms, will be the dead weight
0:22:06 > 0:22:10of millions of tonnes of different kinds of plastics.
0:22:13 > 0:22:16Our ability to take the Earth's resources
0:22:16 > 0:22:18and transform and deposit them in vast quantities
0:22:18 > 0:22:21means we've now made an indelible mark
0:22:21 > 0:22:25in the planet's 4.5 billion-year history.
0:22:43 > 0:22:47We can slice the tops off mountains
0:22:47 > 0:22:50and dig holes big enough to bury a city.
0:22:55 > 0:23:00In a single year, we now move more earth and rock
0:23:00 > 0:23:03than all the natural processes of erosion put together.
0:23:09 > 0:23:13Our machines have transformed the planet.
0:23:23 > 0:23:27So great is our impact on the Earth that it has been used
0:23:27 > 0:23:30to define a new geological epoch...
0:23:35 > 0:23:38..the Anthropocene, the human epoch.
0:23:48 > 0:23:51If you add together all the landscapes we've altered -
0:23:51 > 0:23:55our cities, towns, villages and farmland -
0:23:55 > 0:24:02then 75% of the Earth's ice-free landmass owes its appearance to us.
0:24:07 > 0:24:10This truly is a human planet.
0:24:32 > 0:24:36Sometimes our intervention in the planet's natural processes
0:24:36 > 0:24:39can have surprising and far-reaching consequences.
0:24:49 > 0:24:53This is South Dakota in the United States.
0:25:02 > 0:25:06It's hard to believe it, but this was once a busy little town,
0:25:06 > 0:25:09up to 300 people living here in its heyday.
0:25:10 > 0:25:14It's hard to imagine it as a jostling little farming community,
0:25:14 > 0:25:17but that's exactly what it was.
0:25:27 > 0:25:32In the early 1900s, this was a boom town.
0:25:32 > 0:25:36Farmers poured into the Great Plains of the western USA
0:25:36 > 0:25:38to develop new land.
0:25:40 > 0:25:44You'd think this place would be fantastic for farming.
0:25:44 > 0:25:49The whole landscape is covered in a thick blanket of silts and clays,
0:25:49 > 0:25:51blown or washed in after the last ice age.
0:25:55 > 0:25:58Soil is a mixture of minerals from broken-down rocks
0:25:58 > 0:26:01and nutrients from organic matter.
0:26:03 > 0:26:08It takes more than 500 years to create just 2cm of it.
0:26:13 > 0:26:17What keeps that fine sediment here is the vegetation -
0:26:17 > 0:26:20the grasses bind the topsoil together.
0:26:20 > 0:26:23But the first settlers ploughed over those grasses
0:26:23 > 0:26:28and exposed the delicate soil underneath, and that dried out in the sun.
0:26:31 > 0:26:36When the rains failed in the 1930s, the ploughed-up soil was exposed
0:26:36 > 0:26:39to the full force of the wind.
0:26:39 > 0:26:42The result was devastating.
0:26:42 > 0:26:46It became known as the Dust Bowl.
0:26:48 > 0:26:52Half a million people in the Great Plains were made homeless.
0:26:52 > 0:26:57100 million acres of farmland turned to wasteland.
0:27:04 > 0:27:07The homesteaders of the Great Plains had upset
0:27:07 > 0:27:10the delicate balance of the landscape.
0:27:12 > 0:27:1780 years on, that delicate balance is one we still find hard to keep.
0:27:23 > 0:27:27In China, deforestation and overgrazing
0:27:27 > 0:27:31means soils are being degraded 30 times faster
0:27:31 > 0:27:34than the planet's natural processes can replenish them.
0:27:38 > 0:27:42In Australia, clearing large areas of bush for farmland
0:27:42 > 0:27:46has allowed salt to infiltrate the topsoil,
0:27:46 > 0:27:49damaging around 60,000 square kilometres.
0:27:56 > 0:28:00In total, 25% of the world's farmland has now been degraded
0:28:00 > 0:28:06as an inadvertent consequence of our drive to increase food production.
0:28:10 > 0:28:12There's now an extraordinary contrast
0:28:12 > 0:28:15between the Earth's natural environments
0:28:15 > 0:28:18and the ones that we've created.
0:28:23 > 0:28:25To fully appreciate the extent
0:28:25 > 0:28:29of our interference in the planet's natural processes,
0:28:29 > 0:28:33take a look at one of the Earth's most fundamental cycles...
0:28:37 > 0:28:39...the water cycle.
0:28:42 > 0:28:47Rain that falls over mountains makes its way into streams and rivers.
0:28:52 > 0:28:54This is the Lena River.
0:28:57 > 0:29:00Its headwaters are in the Baikal Mountains,
0:29:00 > 0:29:04where rain and snowmelt set the cycle going.
0:29:06 > 0:29:11It travels 4,500 kilometres across Siberia...
0:29:12 > 0:29:16...before it reaches a huge delta,
0:29:16 > 0:29:19on the edge of the Arctic Ocean.
0:29:21 > 0:29:26Here it returns water to the sea, which evaporates to form clouds,
0:29:26 > 0:29:29and the cycle begins again.
0:29:37 > 0:29:39The Lena is one of the few major rivers
0:29:39 > 0:29:43that still completes the water cycle from source to sea
0:29:43 > 0:29:46without a single man-made interruption.
0:29:53 > 0:29:57Today, we've created an alternative water cycle.
0:30:01 > 0:30:04This is part of the Colorado River system.
0:30:04 > 0:30:09Along its 2,000-kilometre length, it has over 20 dams.
0:30:12 > 0:30:16So much water is diverted to the cities and farmland
0:30:16 > 0:30:18of the American West that most years,
0:30:18 > 0:30:20it no longer reaches the sea.
0:30:25 > 0:30:29The biggest city it supplies is Los Angeles.
0:30:32 > 0:30:36Fresh water is delivered across hundreds of kilometres of desert
0:30:36 > 0:30:40via a network of aqueducts, canals and pipelines.
0:30:42 > 0:30:47This system delivers 90% of the city's fresh water.
0:30:47 > 0:30:50Without it, LA wouldn't exist.
0:30:57 > 0:31:00The veins and arteries of our water supply
0:31:00 > 0:31:03are the lifeblood of our civilisation.
0:31:03 > 0:31:06And the human version of this planetary cycle
0:31:06 > 0:31:10operates at a global scale.
0:31:10 > 0:31:14We have altered the planet's water cycle to such an extent
0:31:14 > 0:31:19that five times as much fresh water is stored in reservoirs
0:31:19 > 0:31:21as flows in all the world's rivers.
0:31:25 > 0:31:30This change in the balance of power between us and the planet is based
0:31:30 > 0:31:35more than anything on our ability to exploit one particular resource.
0:31:54 > 0:32:00This is the Athabasca River, in the heart of Alberta in Canada.
0:32:00 > 0:32:04It doesn't look like it, but today this is a fresh frontier
0:32:04 > 0:32:07in one of the great geological quests of our age -
0:32:07 > 0:32:09the hunt for oil.
0:32:14 > 0:32:17Oil is central to our lives.
0:32:17 > 0:32:20It fuels a mechanised world.
0:32:23 > 0:32:28It's a concentrated form of energy, easily transported.
0:32:28 > 0:32:34Every year we burn around 31 billion barrels of it -
0:32:34 > 0:32:37that's 1,000 barrels a second.
0:32:37 > 0:32:41The problem is... it won't last forever.
0:32:42 > 0:32:45The amount of oil we're burning each year takes the planet
0:32:45 > 0:32:48over three million years to make.
0:32:52 > 0:32:53Thanks...
0:32:53 > 0:32:56Finding more oil is getting harder.
0:33:00 > 0:33:02Some say we've already reached a peak in oil production,
0:33:02 > 0:33:05and that from now on it's all downhill,
0:33:05 > 0:33:08with supply unable to keep pace with demand.
0:33:08 > 0:33:10But others say that's a load of rubbish -
0:33:10 > 0:33:14there's plenty of oil in the ground, it's just a case of finding it.
0:33:14 > 0:33:19For those in the second camp, one of their prime exhibits is here.
0:33:25 > 0:33:31Ah, now, this is what I've come to find. Look at this.
0:33:31 > 0:33:33Looks like the rock's bleeding, doesn't it?
0:33:33 > 0:33:36This place is just full of oil...
0:33:36 > 0:33:40coming out of the rock, and if you look at it, the thing is...
0:33:40 > 0:33:41Look at that - ugh!
0:33:41 > 0:33:44You feel as if, if you just squeeze it, it would come out.
0:33:44 > 0:33:50It's actually a sand, but all the sand grains are just coated in oil.
0:33:50 > 0:33:53We've got a name for this - we call it tar sands -
0:33:53 > 0:33:57and this is just about the dirtiest oil around.
0:33:57 > 0:33:59The whole cliff is just full of it.
0:34:02 > 0:34:07This kind of oil doesn't come shooting out in a great fountain.
0:34:07 > 0:34:09And you don't get at it by drilling down into the ground.
0:34:13 > 0:34:16This is a very different type of oilfield.
0:34:18 > 0:34:22To appreciate just how different it is, you have to go up high.
0:34:42 > 0:34:47Oh, my... Look at that! It's like we've gone into a different world.
0:34:54 > 0:34:57This oil deposit is thought to contain
0:34:57 > 0:35:00almost a trillion barrels of oil.
0:35:00 > 0:35:03It covers 50,000 square kilometres.
0:35:06 > 0:35:10I mean, look at that. The forest just ends there,
0:35:10 > 0:35:15and then after that, just industry for miles upon miles.
0:35:15 > 0:35:19To get at the tar sands involves scraping the surface
0:35:19 > 0:35:21off vast tracts of land.
0:35:21 > 0:35:25This is strip mining for oil.
0:35:25 > 0:35:29Right below me, you can see both the huge attraction of tar sands
0:35:29 > 0:35:31and their Achilles heel.
0:35:31 > 0:35:34On the one hand, there's just vast amounts of oil -
0:35:34 > 0:35:37those fields seem to go on and on forever.
0:35:37 > 0:35:41But on the other hand, getting it out comes at a price,
0:35:41 > 0:35:43a hell of a price.
0:35:46 > 0:35:50Although it's at the surface, it's much harder to extract
0:35:50 > 0:35:52than conventional oil.
0:35:52 > 0:35:54To separate the oil from the sand,
0:35:54 > 0:35:58huge volumes of steam have to be injected into it,
0:35:58 > 0:36:00and that's expensive.
0:36:01 > 0:36:06In a traditional oil well, you'd expect around 25 barrels of oil back
0:36:06 > 0:36:10for every one barrel of energy you use to extract it.
0:36:10 > 0:36:13Here, it's more like one barrel of energy in
0:36:13 > 0:36:15and only five barrels back.
0:36:19 > 0:36:21You know, tar sands may be messy,
0:36:21 > 0:36:24but we still get more energy out of them than we put in.
0:36:24 > 0:36:29So as far as oil's concerned, they're one of our best prospects.
0:36:29 > 0:36:33But it's not exactly an appealing image of hope, is it?
0:36:33 > 0:36:35Can't help but think...
0:36:35 > 0:36:38that we really are scraping the bottom of the barrel.
0:36:45 > 0:36:50The tar sands illustrate that the oil is still out there.
0:36:50 > 0:36:53And new sources are being discovered.
0:36:53 > 0:36:57It's just they tend to be exceptionally hard to reach.
0:37:00 > 0:37:05For centuries, our ingenuity has enabled us to find new forms of energy,
0:37:05 > 0:37:08so it's easy to think that trend will continue.
0:37:10 > 0:37:13History tells us that we don't tend to run out of resources.
0:37:13 > 0:37:18Instead, when push comes to shove, we find new ones.
0:37:18 > 0:37:22But that is a lesson from human history.
0:37:22 > 0:37:26The planet's history has perhaps a more important lesson for us.
0:37:27 > 0:37:32It's a lesson about the most dramatic human influence on the planet -
0:37:32 > 0:37:37the speed and scale at which we're changing the atmosphere.
0:37:55 > 0:37:59Levels of carbon dioxide and methane are higher than at any time
0:37:59 > 0:38:02in the last 15 million years.
0:38:07 > 0:38:10We can already see some of the effects.
0:38:11 > 0:38:14The thickness of the Arctic sea ice has almost halved.
0:38:17 > 0:38:20Some of the extra carbon dioxide we've pumped into the atmosphere
0:38:20 > 0:38:24has been absorbed by the oceans.
0:38:25 > 0:38:27This has increased their acidity by 30%,
0:38:27 > 0:38:31hindering the growth of marine creatures, like corals.
0:38:33 > 0:38:35Over the last few decades,
0:38:35 > 0:38:39the frequency of extreme hurricanes has doubled in some areas.
0:38:46 > 0:38:49We're at the beginning of a dramatic period of change.
0:38:49 > 0:38:52At the heart of it is the greenhouse effect,
0:38:52 > 0:38:56a global warming caused by the gases we release.
0:39:00 > 0:39:04The question is, how will the planet - and our civilisation -
0:39:04 > 0:39:07respond to this change?
0:39:07 > 0:39:11For me, the best way to answer this question is to look back
0:39:11 > 0:39:14into the Earth's past.
0:39:17 > 0:39:19Which is why I've come to the coast of California.
0:39:23 > 0:39:25There's something really strange going on in the ocean over here -
0:39:25 > 0:39:28the whole water looks as if it's fizzing away like mad.
0:39:28 > 0:39:30I've never known anything like it.
0:39:36 > 0:39:39This promises to be an unusual dive.
0:39:39 > 0:39:42The point is to take me back to the last time
0:39:42 > 0:39:48the Earth experienced a rapid and extreme increase in greenhouse gases.
0:40:10 > 0:40:12It's amazing.
0:40:12 > 0:40:15It's like...
0:40:15 > 0:40:17it's like swimming in champagne.
0:40:17 > 0:40:20Everywhere you look,
0:40:20 > 0:40:24wherever you are, you're surrounded with bubbles.
0:40:33 > 0:40:37These bubbles are the key to unlocking one of the Earth's great events.
0:40:41 > 0:40:4655 million years ago, the atmosphere went through something very similar
0:40:46 > 0:40:48to the changes happening today.
0:40:53 > 0:40:55The bubbles are full of a gas called methane,
0:40:55 > 0:40:58which is leaking out of a fault line deep below me
0:40:58 > 0:41:02and heading up there to the atmosphere.
0:41:04 > 0:41:09And it's this speed and intensity of bubble release that's a critical factor.
0:41:09 > 0:41:14Today, only relatively small amounts of methane bubble out
0:41:14 > 0:41:17from seeps like this at the bottom of the ocean.
0:41:17 > 0:41:19But 55 million years ago,
0:41:19 > 0:41:24methane started to erupt from the ocean in massive quantities.
0:41:24 > 0:41:26No-one is quite sure why it happened,
0:41:26 > 0:41:31but huge areas of the ocean would have been bubbling like this.
0:41:31 > 0:41:3455 million years ago,
0:41:34 > 0:41:37these bubbles wouldn't have been fizzing out,
0:41:37 > 0:41:41they would have been belching out. It would have had a devastating effect.
0:41:44 > 0:41:50Methane is 20 times more potent than carbon dioxide as a greenhouse gas.
0:41:50 > 0:41:53And as it burst up through those ancient oceans,
0:41:53 > 0:41:57it led to sudden, runaway global warming.
0:42:22 > 0:42:26That burst in methane levels 55 million years ago
0:42:26 > 0:42:28was the closest experience we've got
0:42:28 > 0:42:32of what continued global warming might bring.
0:42:32 > 0:42:34So what was it that happened to the planet
0:42:34 > 0:42:38during that ancient surge in global warming?
0:42:40 > 0:42:42And what did it mean for life?
0:42:43 > 0:42:46The answer can be found
0:42:46 > 0:42:50nearly 8,000 kilometres away, on the Svalbard archipelago.
0:42:53 > 0:42:56It's well within the Arctic Circle.
0:42:58 > 0:43:0260% of Svalbard is covered in glaciers.
0:43:06 > 0:43:09It's a landscape dominated by ice.
0:43:13 > 0:43:17But 55 million years ago, it was rather different.
0:43:18 > 0:43:21The clues are in the rocks.
0:43:28 > 0:43:30Let's see what we've got. Ooh!
0:43:30 > 0:43:33Ooh, look at this.
0:43:33 > 0:43:36It's what I was hoping to find.
0:43:36 > 0:43:40These rocks are stacked full of ancient leaves.
0:43:40 > 0:43:42Look, there's a frond of a plant there.
0:43:42 > 0:43:47There's another one here. There's a stem with branches going out.
0:43:47 > 0:43:52These rocks are packed full... of leaves.
0:43:52 > 0:43:54Better keep going.
0:43:55 > 0:43:57HE CHUCKLES
0:43:57 > 0:44:01Look at this! Would you believe it?!
0:44:07 > 0:44:09These fossil leaves originate
0:44:09 > 0:44:14from a time just after the methane surge in the oceans.
0:44:14 > 0:44:17They're from a distant relative of the beech,
0:44:17 > 0:44:20a broad-leafed deciduous tree.
0:44:21 > 0:44:24Some of these trees are preserved
0:44:24 > 0:44:27in the permafrost in other parts of the Arctic.
0:44:31 > 0:44:33It's amazing.
0:44:33 > 0:44:39You can just imagine these falling down from trees onto an ancient forest floor.
0:44:39 > 0:44:42But, I mean, today...
0:44:42 > 0:44:46you don't get trees here. You don't get trees like this for hundreds of miles.
0:44:46 > 0:44:49It just tells you that 55 million years ago,
0:44:49 > 0:44:53Svalbard was a very different place.
0:44:54 > 0:44:58Following the methane surge in the ocean,
0:44:58 > 0:45:02global temperatures would have been 10 degrees warmer than they are today.
0:45:04 > 0:45:06It caused immense upheaval.
0:45:06 > 0:45:10Plants and animals were forced to migrate towards the poles.
0:45:12 > 0:45:14Back then, I would have been walking through
0:45:14 > 0:45:20a completely different landscape - subtropical swamps and forest.
0:45:20 > 0:45:23Less High Arctic - more Florida Everglades.
0:45:29 > 0:45:33It would have been inhabited by ancestors of creatures
0:45:33 > 0:45:35like the hippopotamus and the crocodile.
0:45:38 > 0:45:41The lesson from the Earth's past
0:45:41 > 0:45:45is that the world we know today can change out of all recognition,
0:45:45 > 0:45:49simply by raising the level of greenhouse gases in the atmosphere.
0:45:56 > 0:46:00But the remarkable events of 55 million years ago
0:46:00 > 0:46:04offer another, more optimistic, lesson for us.
0:46:04 > 0:46:10Clearly this extraordinary warm period 55 million years ago didn't last -
0:46:10 > 0:46:13otherwise, I wouldn't be dressed like this.
0:46:13 > 0:46:17The planet cooled, ice came to the Arctic.
0:46:17 > 0:46:19So what happened?
0:46:27 > 0:46:29What happened was the Himalayas.
0:46:34 > 0:46:40The creation of this mountain range helped return ice to the Arctic.
0:46:46 > 0:46:50When the tectonic plates of India and Eurasia collided
0:46:50 > 0:46:52around 50 million years ago,
0:46:52 > 0:46:58the result was a mountain range that grew to become the biggest on Earth.
0:47:09 > 0:47:12In building the Himalayas, the planet unleashed
0:47:12 > 0:47:16its most formidable global-cooling weapon...
0:47:18 > 0:47:19..weathering.
0:47:24 > 0:47:28The process begins when carbon dioxide in the atmosphere
0:47:28 > 0:47:31is dissolved in rain and snow.
0:47:31 > 0:47:34This reacts with minerals in the rock
0:47:34 > 0:47:37to form a solution that's carried by rivers to the sea.
0:47:41 > 0:47:45Here, the carbon is absorbed by marine creatures.
0:47:45 > 0:47:49When these die, they sink to the sea floor,
0:47:49 > 0:47:53eventually becoming rock, locking the carbon away.
0:47:57 > 0:48:00Because the Himalayas were constantly rising,
0:48:00 > 0:48:04they were perpetually exposing new rock to the elements.
0:48:04 > 0:48:09This drew more carbon dioxide out of the atmosphere,
0:48:09 > 0:48:11cooling the planet
0:48:11 > 0:48:16and eventually leading to the re-freezing of the Arctic.
0:48:20 > 0:48:24So the planet had an entirely natural way
0:48:24 > 0:48:26of reducing greenhouse gases.
0:48:28 > 0:48:32But there's one obvious problem, and that is
0:48:32 > 0:48:36it takes millions of years to build a mountain range,
0:48:36 > 0:48:39and we don't have the luxury of that sort of time.
0:48:42 > 0:48:46Yet the lesson from history is not entirely wasted.
0:48:48 > 0:48:52Burying carbon has long been the sole preserve of the planet,
0:48:52 > 0:48:56but there's no reason why we can't have a go at doing the same thing ourselves.
0:48:57 > 0:49:02We are now developing ways to take carbon out of the atmosphere.
0:49:07 > 0:49:11One method is to stimulate the growth of immense blooms of algae
0:49:11 > 0:49:17that use photosynthesis to draw carbon dioxide from the atmosphere.
0:49:19 > 0:49:22On land, there are plans
0:49:22 > 0:49:26to create artificial trees that replicate photosynthesis.
0:49:26 > 0:49:29But the biggest challenge
0:49:29 > 0:49:34is to stop carbon dioxide reaching the atmosphere in the first place.
0:49:35 > 0:49:38This can be done by capturing it at source,
0:49:38 > 0:49:42filtering it from industrial chimneys
0:49:42 > 0:49:43and then burying it.
0:49:49 > 0:49:53Scientists are planning to try this out on Svalbard.
0:49:55 > 0:49:59If you happen to have thousands of tonnes of carbon to dispose of,
0:49:59 > 0:50:03the geology here is particularly helpful.
0:50:04 > 0:50:08That cliff behind me is a layer cake of sandstone and shale.
0:50:09 > 0:50:13And that arrangement is perfect for burying carbon.
0:50:17 > 0:50:21This sandstone is ideal for storing the carbon,
0:50:21 > 0:50:25because there's lots of spaces in the pores between the grains.
0:50:25 > 0:50:29And this dense, impermeable shale provides the ideal lid
0:50:29 > 0:50:33that stops the carbon escaping upwards.
0:50:34 > 0:50:39The plan is to drill a number of shafts through the dense shale lid
0:50:39 > 0:50:41and into the sandstone.
0:50:41 > 0:50:45Carbon dioxide will then be pumped down into the sandstone,
0:50:45 > 0:50:48where it will be locked within the pores of the rock.
0:51:04 > 0:51:08Carbon capture won't solve our greenhouse gas problem,
0:51:08 > 0:51:13but it might at least buy us some time to develop cleaner forms of energy.
0:51:15 > 0:51:20Burying and locking away carbon is an attempt to accelerate massively
0:51:20 > 0:51:24what the Earth has done for millions of years.
0:51:24 > 0:51:27It's the beginning of a new approach to the planet,
0:51:27 > 0:51:29deliberately transforming it
0:51:29 > 0:51:34to try and preserve the conditions for our survival.
0:51:39 > 0:51:44Up until now, the effects of our impact on the planet, whether good or bad,
0:51:44 > 0:51:48have been accidental and unintended.
0:51:48 > 0:51:53Whether it's a mud volcano in Indonesia or altering the Earth's climate,
0:51:53 > 0:51:57we never set out to create these changes.
0:52:02 > 0:52:06Science has given us an understanding of how the planet works
0:52:06 > 0:52:11that allows us to protect ourselves against Earth's unpredictable nature.
0:52:13 > 0:52:16But today, we're on the brink of a new era.
0:52:18 > 0:52:24We can now take control of our impact on the planet's natural processes
0:52:24 > 0:52:29and maintain the conditions for civilisation to flourish.
0:52:30 > 0:52:34It's a big challenge, which involves global co-operation.
0:52:36 > 0:52:40But there's an example of what can be achieved here in Svarlbad.
0:52:50 > 0:52:52You know, you'd never know it,
0:52:52 > 0:52:56but locked inside this mountain is something incredibly precious.
0:52:56 > 0:52:59And that...that's the way in.
0:52:59 > 0:53:01It's got a front door!
0:53:01 > 0:53:04HE CHUCKLES
0:53:04 > 0:53:06It looks like something out of James Bond!
0:53:18 > 0:53:24To protect its contents, this facility in Svalbard has been built high enough
0:53:24 > 0:53:28to be above any future rise in sea level.
0:53:28 > 0:53:31It's been excavated so deep into the mountain
0:53:31 > 0:53:34that it would survive a nuclear explosion.
0:53:35 > 0:53:39This is apocalypse planning for our future survival.
0:53:49 > 0:53:52You know, this is a giant vault,
0:53:52 > 0:53:56but in a way it's the modern equivalent of a Noah's ark,
0:53:56 > 0:53:58except that instead of sheltering animals,
0:53:58 > 0:54:02it's preserving the future of the world's food supply.
0:54:07 > 0:54:12The temperature is a constant minus 18 degrees Celsius
0:54:12 > 0:54:16to protect the precious contents stored here.
0:54:27 > 0:54:33This is a shrine to over 10,000 years of agricultural development.
0:54:33 > 0:54:36It's a global seed vault.
0:54:38 > 0:54:39I mean, take this -
0:54:39 > 0:54:42this is rice. But the thing is,
0:54:42 > 0:54:45there's not just one variety of rice in here, there's thousands,
0:54:45 > 0:54:49with different properties and different growing conditions,
0:54:49 > 0:54:51different resistance to disease.
0:54:51 > 0:54:55This is the genetic diversity of rice for the future.
0:55:00 > 0:55:05But of course it's not just about rice.
0:55:05 > 0:55:06This vault will one day store
0:55:06 > 0:55:13every variation of every staple crop from every country on the planet.
0:55:19 > 0:55:22It's a heck of an insurance policy.
0:55:30 > 0:55:34You know, for me, preserving these seeds,
0:55:34 > 0:55:39with all their precious genetic code, makes a really important point.
0:55:39 > 0:55:45And that is, we're taking conscious control over an uncertain world.
0:55:45 > 0:55:48And in that sense, this whole place is like a symbol
0:55:48 > 0:55:51of what can be achieved at a global level,
0:55:51 > 0:55:53if we put our minds to it.
0:55:59 > 0:56:04In this series, we've seen how the fate of past civilisations
0:56:04 > 0:56:07has been shaped by the planet's natural forces.
0:56:09 > 0:56:14The Khmers of Angkor Wat thrived on their ability to exploit the monsoon
0:56:14 > 0:56:17until their growing population
0:56:17 > 0:56:20outstripped their most precious resource - water.
0:56:23 > 0:56:27The Anasazi of Chaco Canyon came to ruin
0:56:27 > 0:56:32when a change in the El Nino cycle led to a sudden, prolonged drought.
0:56:35 > 0:56:38The Minoans of Santorini flourished
0:56:38 > 0:56:42in blissful ignorance of the volcano beneath them
0:56:42 > 0:56:45that would one day would destroy their civilisation.
0:56:51 > 0:56:56Today, our relationship with the planet is a different one.
0:56:58 > 0:57:03We are now a geological force to rival the Earth's natural forces.
0:57:05 > 0:57:09The ultimate test will be how well we use that power.
0:57:16 > 0:57:20As a species, we like to think that we're special.
0:57:20 > 0:57:24Well, this is our chance to prove it.