Fire How Earth Made Us


Fire

Professor Iain Stewart explores man's relationship with fire. Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt and takes a bath in crude oil.


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Transcript


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Our planet has immense power...

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..and yet that's rarely mentioned in our history books.

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I'm here to change that.

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I'm looking at four ways the power of the planet has shaped our history.

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The deep Earth that provided the raw materials for our conquest of the planet.

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Wind...that has influenced the rise and fall of empires.

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Water.

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Look at that!

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Our struggle to control it has defined the character of civilisations.

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But this week I'm looking at fire.

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It's deadly,

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yet it's also the driving force behind human progress.

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But our dependence on fire has meant that events deep in the Earth's past

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have changed the course of history.

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The vibrate is a low-air alarm.

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It'll let you know when you've got a quarter of a tank of oxygen.

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-When you hear that, you need to get out.

-Get out. OK.

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I'm preparing to undergo an experience that,

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on the face of it, is absolutely terrifying.

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AIR HISSES

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These stickers are to measure the temperature it reaches inside the suit.

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These will tell you how hot you're actually getting inside the suit.

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-So how hot does it go up to?

-130 degrees Fahrenheit.

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-That goes over your head.

-Mm-hm.

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OK. I'm fine.

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My suit is eight layers thick,

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its visor specially tempered, gold-plated glass.

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And I've got my own air supply.

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This is what it takes to survive just a few seconds...

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HISSING

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..inside the heart of a fire.

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FLAMES ROAR AND CRACKLE

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The temperature around me is 1,600 degrees Celsius.

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For all its danger, fire is compelling -

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almost hypnotic.

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Oh, my gosh!

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-HIS BREATHING HISSES

-Argh! Argh!

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MAN: Get his gloves. Get his gloves off.

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-MAN: Come on out. Go on! Go on!

-Argh! Oh!

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That was scary, right at the end.

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-That was scary.

-INAUDIBLE QUESTION

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No, no, no. I feel my arms burning, though. Ha-hargh!

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I'll move them around.

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Ah! That...

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..that is not a place where humans should be.

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But when you're going through and you see the flames licking up in front of you,

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just the raw energy of it is absolutely entrancing.

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But I'm burning.

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I mean, actually, my elbow, my hand... Argh-ha-ha!

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..is burning.

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I think I should get this off, actually.

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The paradox of fire is that it's lethal,

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and yet we depend on it completely.

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Fire generates our electricity.

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It drives our machines.

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We use it every day.

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But the history of our relationship with fire

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reveals how the Earth has exerted enormous power

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over the fate of peoples and nations.

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It's strange to think that for 90% of Earth's history,

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there simply was no fire.

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Ours was a barren planet of dust and rock.

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There was nothing to burn.

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Not until relatively recently,

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about 400 million years ago,

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did fire first appear.

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The key to this transformation...

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..vegetation.

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The first land plants had just appeared...

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..and they provided fuel for fire.

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But plants did something else as well.

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Every kid likes to climb trees,

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and the great thing about being grown up is the trees...

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they just get bigger, and the ways to get up them just get fancier.

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Vegetation supplied a second crucial ingredient for fire.

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HE GRUNTS

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You can see how up here in the forest canopy.

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Going on all around me is a chemical reaction - photosynthesis.

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It's happening in here, in the leaves.

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And what the photosynthesis is producing as a waste product

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is an essential ingredient for fire...

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oxygen.

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Flames cannot burn unless at least 13% of the atmosphere is oxygen.

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But the Earth's early atmosphere had almost none.

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Photosynthesising plants used sunlight to convert carbon dioxide into energy...

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..and in the process released oxygen.

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By around 400 million years ago,

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this process had raised the level of oxygen in the atmosphere

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to that critical 13%.

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Now there was only one more thing needed for fire to start.

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THUNDER CRASHES

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A spark.

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Starting fire was actually the easy bit.

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Lightning storms have raged on Earth

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for almost its entire history.

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30,000 bolts of lightning hit the ground every hour.

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THUNDER RUMBLES AND CRASHES

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CRACKLING AND ROARING

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For hundreds of millions of years,

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wildfires were controlled only by the forces of nature.

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They started spontaneously,

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spread freely...

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..and only stopped when they ran out of fuel

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or the rains came.

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But then something changed.

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We came along.

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Around 1.5 million years ago,

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early humans learnt how to control fire.

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Our distant ancestors probably first captured fire

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by grabbing a burning stick from a wildfire and keeping it nourished,

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fanning the flames to keep it alight.

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It was the beginning of a relationship that would transform the planet...

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and us.

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In that sense, fire is the human signature.

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It gave us immense power over our world.

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Cooking greatly expanded the range of foods available to us.

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It gave us warmth and light...

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..and protection against hungry predators.

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It allowed us to quickly clear large areas of land.

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Fire was the weapon that began our conquest of the planet.

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Fire was so central to our survival,

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perhaps it's no surprise that it was worshipped by some early civilisations.

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In the Middle East, one of the oldest religions in the world, Zoroastrianism,

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grew up around the worship of fire.

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For the Zoroastrians, the flame itself was sacred.

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Humans have always been drawn to fire.

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Flames have long been a symbol of a spirit far greater than ourselves -

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almost a divine presence.

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To this day, the eternal flame is still a potent symbol

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for the world's great religions.

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But the greatest landmark in our use of fire came about 6,000 years ago.

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The breakthrough centred on an extraordinary element - carbon.

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This is carbon in its purest form...

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..diamond.

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This particular stone is 25 carats

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and apparently it's worth £3.3 million.

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It's absolutely beautiful.

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Diamonds are made under extreme pressures and temperatures

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deep in the Earth.

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I've always loved the idea that the ultimate in glitz

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was to adorn ourselves in tiny pieces of the Earth's interior.

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Geological bling.

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But there are other forms of carbon that are far more valuable to us than this...

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..because carbon is the basis for all life on Earth.

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And it's the key ingredient in fire.

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And once again, it depends on photosynthesis.

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Plants use the sun's energy

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to extract carbon from carbon dioxide in the atmosphere,

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and use it to create their living tissue.

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It is this carbon that burns in a fire,

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releasing the energy that originally came from the sun as heat.

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The more carbon-rich a fuel is, the more heat it produces.

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Normal wood fires burn at about 700 degrees Celsius.

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But 6,000 years ago, our ancestors discovered the trick of burning wood

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in a low-oxygen environment.

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It only partially burns,

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but in doing so it creates a much purer, carbon-rich fuel...

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..charcoal.

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And that can burn at 1,100 degrees Celsius...

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..hot enough to melt metal out of rock.

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The invention of metal smelting, culminating in the use of iron,

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was one of the most critical turning points in human history.

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The age of metals had begun.

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HISSING

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CLANG!

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Our mastery of metal gave us tools...

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..money

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and weapons.

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It was the foundation on which human progress was built.

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So much so that by the Middle Ages,

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the production of charcoal for iron smelting was a major industry.

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But there was an inevitable problem.

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People began to run out of wood.

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CRACKING, SPLINTERING AND RUSTLING

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In prehistoric times,

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Britain had been almost completely covered in forest,

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but by the end of the 16th century,

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90% of the ancient woodland had gone.

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In London, which was growing fast,

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the shortage of accessible wood meant that the price rocketed.

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Around the growing cities of Europe and Asia,

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similar fuel shortages developed.

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In fact, the end of the 16th century

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was the world's first great energy crisis.

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In many societies, the demand for energy

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had reached the limits of what photosynthesis could provide.

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A new source of carbon was needed.

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And the planet had a solution.

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The answer to the energy shortage started out in cold, wet places...

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..like here in Oregon, in the western United States.

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This looks like a perfectly ordinary -

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if very beautiful - lake, but these waters hold a secret.

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Because down there is a lost world...and a very cold one.

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Melting glaciers keep the water clear.

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Ghostly shapes appear in the distance...

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..standing like sentinels.

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But this is not their natural home.

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These are 3,000-year-old tree trunks...

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..the remains of a drowned forest.

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They were submerged when lava from a nearby volcano dammed this valley

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and created the lake.

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These trees are completely waterlogged, but they're actually

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the crucial first stage in an extraordinary transformation.

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BREATHING HISSES

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Because the trees are under water, there is no oxygen to help rot them away.

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Instead, they're preserved, and eventually buried in mud

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at the bottom of the lake...

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..the start of a long transformation which turns wood

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into something very different.

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Oh!

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That was incredible.

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-It's absolutely freezing, though.

-HE SNIFFS

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The thing is, today, there are precious few places

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where whole forests die and get preserved,

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but 300 million years ago, this was happening right across the globe.

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It was just a lot warmer then!

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300 million years ago, trees dominated the planet.

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Many of these forests were in lowland swamps.

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So when the trees died, they fell into the water.

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In fact, so many carbon-rich trees were buried

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that this period in the Earth's history

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is known as the Carboniferous -

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the Age of Carbon.

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Eventually, these drowned trees would be squeezed and cooked

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deep inside the Earth and turned into something new and different.

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Coal.

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Coal was to change our relationship with fire in a fundamental way.

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Instead of burning carbon from the present, coal gave us access

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to a huge new source of carbon from the Earth's past.

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Coal was, in essence, an immense store of fossilised sunshine.

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But coal wasn't evenly distributed across the Earth,

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and this meant that from the 17th century onwards,

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the planet began to play a new and crucial role in human history.

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The first place to benefit was a small, north-European island...

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Britain.

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Britain was lucky.

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It had an abundance of coal,

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much of which could be easily collected from the surface.

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From the beginning of the 17th century,

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burning coal began to replace wood in homes and workshops.

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It was the beginning of a transition

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that would end up changing Britain and the world.

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To see how, I'm heading to the Forest of Dean, in Gloucestershire.

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It didn't take long for all that easy-to-get-at coal to be used up,

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so the miners were forced to tunnel into the Earth,

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chasing the coal seams underground,

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and down there they had a problem.

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But it was a problem which, it turned out,

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would unleash the Industrial Revolution.

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In the process, mining condemned millions

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to a dusty, dirty, existence as men and even children

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were sent underground.

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This mine is the nearest I can get

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to experiencing what early coal mining was like.

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It's owned by Robin Morgan, who's spent all his life mining.

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Is it falling down?

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No, I'm just putting this one back up. This is a new one I'm putting in here.

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So there we go.

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That's right - drop him down there in that hole, like that.

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The first mine I ever went down,

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-I was only 13 years of age.

-Oh!

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My two brothers had their own mine.

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They used to drop me down a shaft 100 foot deep

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in a 40-gallon drum with two hooks in the side

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on a hand winch.

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So where's the coal? That's what I'm looking forward to seeing.

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Well, the coal seam is actually on in there.

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-I can take you on into the seam.

-Yeah, please.

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-Keep your head down here.

-Yeah, OK.

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Just like the early miners, Robin hacks out the coal by hand.

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Robin, do you think I could have a go?

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You can have a go, by all means, Iain. But there's not much room up here.

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All right.

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PANTS WITH EFFORT

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Ah, dear, dear!

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I thought coal was supposed to be soft!

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Swing the pick instead of just tapping it.

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You've got to pull the pick right back

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and swing it right into those two-inch layers, and they will prise off there.

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Oh!

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My arms hurt. How do you do it, Robin?

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You get used to it over the years, you know.

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I mean to say, you've only been up there five minutes.

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-LAUGHING:

-I know! I have!

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-You will gradually get used to it.

-And you've been...

-HE SPITS

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I like rocks all right, but...

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spending 12 hours a day smashing lumps out of them...

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-Well, that coal isn't as hard as rocks.

-No.

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As you are performing at the moment, I definitely wouldn't give you a job,

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because the rate you're getting that off, you would not survive.

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But in the 17th and 18th centuries,

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the problem for Britain's miners

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was more fundamental than a lack of muscle power.

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The trouble was, the deeper they tunnelled,

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the more likely they were to encounter a major obstacle.

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Water, and plenty of it.

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300 years ago, when miners first followed the coal seams underground,

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this was a problem they faced,

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and solving this problem was the key to our industrial transformation.

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Once the miners got down to the water table, their tunnels flooded

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and the coal became inaccessible.

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It was impossible to pump the water out by hand.

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A technological solution was desperately needed...

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..and in the early 18th century, engineers came up with one.

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The steam engine.

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It was designed specifically to pump water out of mines,

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but it soon found other uses.

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Within decades, the combined power of steam and coal became the force

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behind an extraordinary, integrated economy.

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WHISTLE HOOTS

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Coal fuelled the blast furnaces which smelted steel.

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The steel was turned into trains and ships,

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powered by steam engines of course, which in turn burnt more coal.

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Today, we know this transformation in our use of fire

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as the Industrial Revolution.

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You know, being down here really focuses your mind.

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Britain owes a tremendous amount

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to that distant geological age when trees ruled the world.

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Think of the Industrial Revolution

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as the rise of carboniferous capitalism.

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But the planet was fickle with its favours.

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Britain was given huge reserves of coal

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and the geography to exploit it.

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Not everywhere was so lucky.

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There was another country

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blessed by the planet with huge reserves of coal.

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In the 17th century,

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it too was poised on the edge of an industrial revolution,

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but its story played out rather differently.

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That country

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was China.

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By this time, China had been moulded into a vast empire.

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It was rich and technologically advanced.

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China seemed perfectly positioned to exploit its coal reserves.

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There was one problem.

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China's coal reserves may have been massive,

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but they were a long way from the country's cities on the coast.

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However, running straight from the coalfields to the sea

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was the mighty Yellow River.

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So, in theory,

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transporting the coal to the market should have been possible.

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This is Qikou, a beautiful old town on the Yellow River.

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It's right in the heart of coal country.

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If coal was to be carried downstream to the coast,

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it would have to pass through here.

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Hello. How are you?

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Mr Li is 76 years old, and he's been navigating these waters since he was 11.

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His son runs a local ferry service.

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The water looks very calm.

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Very still - the water.

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Cos I get seasick.

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Can I get on? OK.

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The Li family are going to take me down the river

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in a traditional, flat-bottomed boat - a design used for generations.

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This is the route

0:31:030:31:05

that coal from China's coalfields would have had to travel.

0:31:050:31:08

It's like a nice, relaxing row down the Thames.

0:31:110:31:15

But just downstream from Qikou is an obstacle.

0:31:210:31:25

Mr Li and his friends, who boast an average age of 75,

0:31:320:31:37

are the last people who know how to ride these rapids.

0:31:370:31:40

SCRAPING

0:31:460:31:47

These rapids are only here because the channel of the Yellow River

0:31:490:31:52

gets constricted between these boulders over here and this hard rock here.

0:31:520:31:57

It's literally caught between a rock and a hard place.

0:31:570:32:00

It means it's really choppy.

0:32:000:32:02

And it would be even harder to get through if we were laden down with coal.

0:32:080:32:12

MAN SHOUTS

0:32:200:32:22

Well, we made it! Just a couple of hairy moments, but...

0:32:250:32:29

Mind you, it wasn't the worst set of rapids in the world,

0:32:290:32:32

but it makes you realise that if you're taking a bulky cargo like coal down here,

0:32:320:32:37

then either it or us are going to end up in the drink, at the bottom of the river.

0:32:370:32:42

This is only the start.

0:32:440:32:46

Downstream, there are many more rapids.

0:32:460:32:49

MAN SHOUTS

0:32:500:32:53

And just to add to the difficulties, the only way to get the boat

0:32:540:32:58

back upriver is sheer manpower.

0:32:580:33:02

What these rapids meant was

0:33:040:33:06

that you could transport goods downstream as far as Qikou over there,

0:33:060:33:09

but it was impossible to take it further.

0:33:090:33:12

For cargo boats, these rapids were the end of the line.

0:33:120:33:16

So the only way to get the coal to market was to carry it overland to the coast...

0:33:200:33:25

..1,000 kilometres away.

0:33:260:33:29

But its price doubled every 40 kilometres.

0:33:300:33:35

The geography of the Yellow River ensured

0:33:370:33:39

that coal could never be shipped directly to the big coastal markets,

0:33:390:33:45

and that meant that the empire was effectively cut off

0:33:450:33:48

from the vast reserves that could have completely transformed it.

0:33:480:33:52

The British invented the steam engine to overcome

0:33:570:34:00

the barrier posed by flooded mines.

0:34:000:34:02

But the Chinese failed to find a similar solution

0:34:040:34:08

to their geographical problems.

0:34:080:34:10

It was one of those moments

0:34:100:34:12

when human factors interacted

0:34:120:34:14

with the opportunities the planet had to offer.

0:34:140:34:17

While Britain was forging an industrial revolution,

0:34:210:34:24

the Chinese were building these enormous gardens at Chengde.

0:34:240:34:30

They were designed to celebrate the size and diversity of the empire.

0:34:310:34:35

There was a miniature replica of the Yellow River...

0:34:380:34:41

..a smaller version of the Great Wall...

0:34:430:34:46

and even a copy of the Dalai Lama's palace in Tibet.

0:34:460:34:51

These gardens symbolised China's preoccupation

0:34:510:34:55

with managing its vast territory.

0:34:550:34:57

It was such a high priority

0:35:000:35:02

that rather than focusing on technological innovation,

0:35:020:35:06

the brightest minds were sucked into running the empire.

0:35:060:35:11

Not until the middle of the 20th century

0:35:160:35:19

did China build extensive road and rail systems into its heartland

0:35:190:35:24

and start its own industrial revolution.

0:35:240:35:27

Ironically, China is now the biggest user and producer of coal in the world.

0:35:290:35:35

China's rulers might not have found a way

0:35:460:35:49

to solve their fuel crisis 300 years ago, but its people had a go.

0:35:490:35:54

They came up with a brilliant invention, which today is known across the world.

0:35:540:36:01

Until the 16th century, Chinese cuisine was renowned

0:36:010:36:05

for its delicious stews, which took loads of time and loads of wood to cook.

0:36:050:36:09

So in an era of growing wood shortage,

0:36:090:36:12

a radical new approach was needed, and this was it -

0:36:120:36:15

the wok.

0:36:150:36:17

It's funny to think that a crippling wood famine gave us

0:36:180:36:21

one of the most famous cuisines in the world - the Chinese stir-fry.

0:36:210:36:26

The story of coal shows how the planet

0:36:370:36:40

played a crucial role in transforming the fate of nations

0:36:400:36:43

at the time of the Industrial Revolution.

0:36:430:36:46

It turned fire into the energy that fuelled human progress.

0:36:500:36:54

And yet that was only the beginning.

0:36:560:36:59

Today, the planet's stores of ancient carbon

0:37:000:37:03

have an even greater impact on our world.

0:37:030:37:05

That impact hinges on another type of buried carbon.

0:37:100:37:14

To see how it's formed,

0:37:180:37:20

I've come to an amazing cave on an island off southern Iran.

0:37:200:37:24

BANGING AND MUFFLED SPEECH

0:37:270:37:30

-MAN: Do this one up nice and tight.

-Cheers.

0:37:310:37:34

-Is it straight down?

-Yeah.

0:37:360:37:37

There's a little bit of a lip and then it goes straight down,

0:37:370:37:40

and then it opens out wide and you just drop into space.

0:37:400:37:43

The last drop, 10-15 metres, you're in space.

0:37:430:37:46

I just looked. Oh, my God!

0:37:480:37:51

I have to abseil 50 metres to enter the cave system.

0:37:530:37:58

Inside is evidence that reveals

0:37:580:38:01

where this other store of ancient carbon comes from and how it's made.

0:38:010:38:05

That is just plain weird.

0:38:170:38:19

Look at those colours!

0:38:190:38:20

I'm heading for some caverns that are even deeper underground.

0:38:260:38:30

PANTING

0:38:350:38:37

Phew!

0:38:390:38:40

GRUNTS

0:38:400:38:42

Oh!

0:38:500:38:51

This...has got to be the toughest

0:38:510:38:54

and scariest cave climb I've ever done.

0:38:540:38:57

There's 100 metres of solid rock above me,

0:38:570:39:01

but it's going to be worth it,

0:39:010:39:03

because ahead is one of the most unusual cave systems in the world.

0:39:030:39:08

Most caves are made from solid rock.

0:39:120:39:14

This cavern is different.

0:39:160:39:18

Oh, wow, look at these!

0:39:240:39:26

These are stalactites.

0:39:260:39:29

They're the weirdest ones I've ever seen.

0:39:300:39:32

Normally, stalactites are made of limestone

0:39:320:39:35

and they drip vertically down, but these,

0:39:350:39:38

if you look at them closely,

0:39:380:39:40

they're made of small crystals that twist and turn.

0:39:400:39:43

You can check what they're made of really easily. You just need to lick them.

0:39:460:39:49

Wow! Yeah... salt.

0:39:510:39:53

Written in the roof is a clue to where the salt came from.

0:40:160:40:21

This magnificent, striped banding is a real giveaway clue.

0:40:240:40:27

The layers are formed when seawater evaporates away,

0:40:270:40:32

leaving behind a thin residue of salt crystal.

0:40:320:40:35

This is all evidence that the salt rock

0:40:350:40:37

was originally laid down in an ocean that dried up.

0:40:370:40:41

To create so much salt, you need to evaporate an awful lot of seawater.

0:40:560:41:01

Usually, this happens in shallow seas

0:41:020:41:06

which get cut off from the rest of an ocean.

0:41:060:41:09

Seawater then evaporates, leaving behind a thick layer of salt.

0:41:090:41:14

But it's not only salt that gets left behind

0:41:160:41:19

when an ocean evaporates.

0:41:190:41:21

Shallow seas are the most biologically productive part of the ocean.

0:41:250:41:29

They're teeming with life...

0:41:290:41:31

..all made from carbon.

0:41:320:41:34

When marine creatures die, their skeletons build up on the sea floor.

0:41:420:41:47

Over millions of years, these skeletons are transformed

0:41:480:41:51

into a sludge of carbon and buried under sediment and layers of salt.

0:41:510:41:58

One of the best places to see what that sludge ends up looking like...

0:42:010:42:05

..is in the republic of Azerbaijan.

0:42:060:42:10

Here they call it naftalan.

0:42:170:42:19

It's been used as a health treatment for thousands of years,

0:42:240:42:28

hailed as a cure for everything from rheumatism to baldness.

0:42:280:42:32

Look at that!

0:42:450:42:46

That looks disgusting!

0:42:460:42:48

GURGLING

0:42:490:42:52

It's said that 4,000 years ago,

0:42:520:42:54

the Babylonians mixed this stuff with beer and drank it as a medicine.

0:42:540:42:58

But there is another way to enjoy its healing properties.

0:43:000:43:05

Ah...

0:43:120:43:13

Ugh! It's so weird!

0:43:130:43:17

Ah...

0:43:180:43:19

Ugh!

0:43:190:43:21

It's so clingy.

0:43:210:43:23

Oh, my God!

0:43:230:43:25

Oh...

0:43:300:43:32

Ah...

0:43:320:43:34

People have been doing what I'm doing

0:43:390:43:41

way back to the time of the ancient Persians, although Lord knows

0:43:410:43:45

what made them get their kit off and start to bathe in this stuff.

0:43:450:43:49

I must admit, when I first saw it, it looked absolutely disgusting.

0:43:510:43:55

The feeling of it being warm and clingy was horrible.

0:43:550:44:00

But now, after five minutes,

0:44:000:44:03

it still feels absolutely disgusting.

0:44:030:44:06

Just as well this isn't its only use.

0:44:100:44:13

You known, I think I can smell someone smoking,

0:44:170:44:21

which is making me a bit jittery, because...

0:44:210:44:23

well, because this is oil.

0:44:230:44:26

I'm lying in a bath of petroleum.

0:44:260:44:30

Ugh!

0:44:300:44:31

ROARING

0:44:370:44:39

Today, we've thought of a few more ways of using oil.

0:44:410:44:45

It's the ultimate source of concentrated carbon energy.

0:44:450:44:49

It's more energy-rich than coal, easier to transport,

0:44:500:44:54

and it's got a million different uses.

0:44:540:44:57

The use of oil is the pinnacle of our mastery of fire.

0:45:060:45:10

Fittingly, the first country to benefit from the exploitation of oil

0:45:150:45:19

was the home of naftalan...

0:45:190:45:21

..Azerbaijan.

0:45:220:45:24

For centuries, this thick, black, oily sludge

0:45:290:45:32

was dug out of the ground here by hand, on a small-scale basis.

0:45:320:45:36

But in the middle of the 19th century, demand for oil really took off,

0:45:360:45:40

and what had been a cottage industry turned into this.

0:45:400:45:44

Within 20 years, these fields were the site

0:46:050:46:08

of the first great global oil boom.

0:46:080:46:11

From across the world,

0:46:110:46:12

entrepreneurs rushed to Azerbaijan to make their fortunes.

0:46:120:46:16

Some succeeded so well that their names are almost legendary.

0:46:160:46:20

The Shell oil company started life here, and the Nobel brothers of Nobel prize fame

0:46:200:46:26

built their business empire on Azeri oil.

0:46:260:46:30

This place oozed money!

0:46:300:46:33

By the early 1900s,

0:46:420:46:44

Baku, the capital of Azerbaijan,

0:46:440:46:48

boasted more millionaires than anywhere else on Earth.

0:46:480:46:51

But Azerbaijan really owed its sudden wealth to a fluke of geology.

0:46:580:47:04

In the land of naftalan, oil happens to be exceptionally close to the surface.

0:47:140:47:19

You can see how close at an unusual location in the south of the country.

0:47:230:47:28

If you want to appreciate why this country was the site of the first great oil boom,

0:47:330:47:37

you don't have to look any further than these curious mounds.

0:47:370:47:41

It's not so much the mounds that's interesting,

0:47:410:47:43

it's what's bubbling out of them - mud.

0:47:430:47:45

But not just ordinary mud.

0:47:450:47:47

Look what happens when I do this.

0:47:470:47:49

D'oh!

0:47:570:47:58

GLOOPING

0:48:010:48:04

The reason it's flammable is that the mud is full of natural gas,

0:48:060:48:11

which is formed along with the oil.

0:48:110:48:13

You know, these things are like miniature volcanoes, really...

0:48:160:48:20

..except that rather than hot, molten lava spewing out of the top,

0:48:220:48:26

it's just mud.

0:48:260:48:28

The thing is, you can dig into them, and you can see

0:48:280:48:33

what the kind of plumbing is like inside, which is exactly what I'm doing now.

0:48:330:48:37

GRUNTS

0:48:390:48:40

Ah, now, look at this, look at this.

0:48:400:48:42

You can see it in here.

0:48:420:48:45

Mud is just bubbling up in this cavity, and then there's a little vent pipe

0:48:450:48:50

that carries it up to the top, where it spews out.

0:48:500:48:53

BUBBLING

0:48:530:48:55

There were few places on Earth

0:48:570:48:59

where it was easier to extract oil and gas than Azerbaijan.

0:48:590:49:02

PLOPPING

0:49:020:49:04

But by the start of the 20th century, demand for oil was rocketing,

0:49:060:49:10

and new sources had to be found.

0:49:100:49:14

Once again, the Earth's distant past would play a decisive role

0:49:170:49:21

in meeting our needs.

0:49:210:49:23

The big question is why a few lucky places ended up with huge oilfields,

0:49:270:49:33

but others didn't.

0:49:330:49:34

I don't think it's an exaggeration to say that the answer to that puzzle

0:49:340:49:38

has shaped the global geopolitics of our age.

0:49:380:49:42

It's probably the most powerful way that the Earth has influenced human history.

0:49:420:49:47

After Azerbaijan faded from prominence,

0:49:520:49:55

the Middle East became the key oil-producing region in the world.

0:49:550:49:59

It owes this good fortune to a chain of events that began

0:50:010:50:06

almost 300 million years ago.

0:50:060:50:08

Back then, the two areas

0:50:120:50:14

that would one day form most of the modern Middle East were separate,

0:50:140:50:19

but they were on the move.

0:50:190:50:20

Remarkably, as they moved,

0:50:230:50:25

both areas spent much of the time submerged by shallow seas.

0:50:250:50:30

So layer upon layer of dead sea creatures built up on the ocean floor.

0:50:330:50:38

And when, periodically, the seas evaporated,

0:50:400:50:43

layers of salt were also deposited.

0:50:430:50:46

As the modern Middle East came together,

0:50:520:50:54

these layers were buried deep inside the Earth,

0:50:540:50:57

where the heat and pressure turned the dead sea creatures into oil.

0:50:570:51:02

But the Earth played one final role in turning this area

0:51:110:51:14

into the dominant oil-producing region in the world, and to see what it is...

0:51:140:51:19

..I've come to an unusual mountain range in Iran.

0:51:210:51:25

The drifting continents helped form the oil, but in most areas

0:51:300:51:35

the oil was buried deep in the Earth.

0:51:350:51:37

Too deep to be exploited.

0:51:430:51:45

It needed to be brought closer to the surface,

0:51:470:51:50

which is where salt returns to the story.

0:51:500:51:54

As a geologist, I've been lucky enough

0:51:540:51:56

to go to a lot of places and see a lot of rocks,

0:51:560:51:59

but nothing really prepares you for what you find here.

0:51:590:52:02

Cos here I am, walking in the scorching desert sun, looking down on a glacier.

0:52:020:52:08

But that isn't made of ice - it's made of salt.

0:52:080:52:12

This whole mountainside is covered in salt

0:52:170:52:21

that's oozed upwards from deep inside the Earth...

0:52:210:52:24

..the remains of a long lost ocean.

0:52:260:52:30

You know, this is such a surreal landscape.

0:52:440:52:47

What's hard to take is that virtually everything under my feet is moving.

0:52:470:52:51

You can see that - look at this here.

0:52:510:52:53

Look at these cracks that are opening up in the salt

0:52:530:52:56

as it opens up and then closes again.

0:52:560:52:59

And then also, here and there... Look, there's a bit.

0:52:590:53:02

This was carried down the glacier by the salt from somewhere up there.

0:53:030:53:09

I mean, this is exactly what ice does.

0:53:090:53:12

Salt is similar to ice because it's soft and plastic, which is why it flows.

0:53:170:53:22

On the Earth's surface, this means it can slide across the land like a glacier.

0:53:240:53:29

But even more spectacular

0:53:350:53:37

is the role it played underground in the formation of oil reserves.

0:53:370:53:43

As the continents collided to form the Middle East,

0:53:480:53:51

layers of salt and oil-rich rock strata began to buckle upwards.

0:53:510:53:57

The salt made it much easier for the rock to bend, until eventually...

0:53:570:54:02

..it cracked.

0:54:050:54:07

Now the oil could flow upwards until it was trapped in a fold in the rock,

0:54:070:54:12

kept in place by an impermeable layer above.

0:54:120:54:15

The salt helped the rock slide easily,

0:54:190:54:22

acting as a kind of lubricant, creating huge folds called anticlines,

0:54:220:54:27

which were perfect for trapping oil.

0:54:270:54:29

And where there are oil traps, there are generally oilfields.

0:54:290:54:34

If you take a look at a map of the world's buried salt deposits,

0:54:350:54:39

and overlay the major oilfields,

0:54:390:54:42

it's easy to see why geologists searching for oil go looking for salt.

0:54:420:54:46

It takes millions of years,

0:54:510:54:53

and some pretty extraordinary geological events, to create

0:54:530:54:57

an oil trap that we can exploit.

0:54:570:54:59

So it's not surprising that only a few countries have oil beneath them.

0:54:590:55:03

And when they find it, there's almost no limit to what they'll do

0:55:030:55:09

to get it out of the ground.

0:55:090:55:11

Nowhere symbolises this determination more than this town

0:55:130:55:17

in the former Soviet Union.

0:55:170:55:20

At first glance, this looks like your typical Eastern European town.

0:55:240:55:28

You've got your standard-issue apartment blocks,

0:55:280:55:31

and the architecture has got a real industrial feel to it.

0:55:310:55:34

It was first started in the 1940s.

0:55:400:55:42

It's got a football team...

0:55:440:55:46

..and even a mosque.

0:55:490:55:51

This place is called Oily Rocks,

0:55:540:55:57

and over 2,000 people live and work there.

0:55:570:56:00

If ever there was a monument to our obsession for oil, then this is it.

0:56:000:56:04

Because what you don't see from the ground is that Oily Rocks

0:56:040:56:08

was built in the middle of the Caspian Sea.

0:56:080:56:11

It's 50 kilometres from dry land.

0:56:240:56:27

Over the years, more than 600 oil wells

0:56:280:56:31

have been drilled from these platforms.

0:56:310:56:34

Today, Oily Rocks is still producing oil, but it's past its peak.

0:56:350:56:41

And that about sums up our relationship with oil more generally.

0:56:440:56:48

Today, we're burning it far faster than the planet can make it.

0:56:530:56:57

It would take the Earth three million years to make enough oil

0:56:570:57:03

for just one year of our consumption.

0:57:030:57:05

We've reached a turning point in human history.

0:57:120:57:16

Every major advance in human civilisation has been made possible

0:57:190:57:23

by our ability to raid the Earth

0:57:230:57:26

for ever more energy-rich forms of carbon.

0:57:260:57:29

But our love affair with burning carbon-based fuel is coming to an end.

0:57:310:57:36

Carbon itself has become the problem.

0:57:390:57:43

Burning it produces greenhouse gases which are changing our climate.

0:57:430:57:47

And that means if human civilisation is to continue to advance,

0:57:500:57:55

we will have to break the link between progress and the burning of carbon.

0:57:550:58:00

Next time, a very different planetary force...

0:58:110:58:15

us.

0:58:150:58:16

We are changing the surface of the planet more

0:58:160:58:19

than all the forces of nature put together.

0:58:190:58:23

But are we threatening the Earth's ability to support human civilisation?

0:58:240:58:29

E-mail: [email protected]

0:58:560:58:59

Professor Iain Stewart continues his epic exploration of how the planet has shaped human history.

Iain explores man's relationship with fire. He begins by embarking on an extraordinary encounter with this terrifying force of nature - a walk right through the heart of a raging fire.

Fire has long been our main source of energy, and Iain shows how this meant that the planet played a crucial role in Britain's industrial revolution, whilst holding China's development back.

Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt, crawls through an extraordinary cave in Iran and takes a therapeutic bath in crude oil.


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