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NARRATOR: Our planet is full of
astonishing natural wonders.

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Look at that!

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Oh!

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It 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 that the power
of the planet has shaped our history.

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The power of fire,

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the source of great
technological breakthroughs.

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Water...

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Oh, my gosh!
You're getting all wet there.

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...our struggle to control it
has directed human progress.

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The deep Earth...

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Blooming heck! That really is deep.

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...that provided the raw materials
for our conquest of the planet.

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But this time I'm looking at
the power of the wind.

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For thousands of years,

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the wind has shaped the destiny
of peoples across the globe.

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It has built fortunes and brought ruin.

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Even today, we're still
at the mercy of the wind.

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(WIND WHISTLES)

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People have exploited the wind
for thousands of years,

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on land and, most of all, at sea.

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And to really experience its awesome
force, this boat is the place to be.

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This is one of the fastest
sailing boats ever built.

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It's capable of up to 5O miles an hour.

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And when you're down close to the water,

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you can really feel
that phenomenal speed.

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But what makes this thing really special
is when it starts to fly.

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Whoo!

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(LAUGHS)

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But the real key to this craft's
phenomenal breakneck pace is up there.

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The sail. There's enough of it
to actually cover a tennis court,

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every inch of it grabbing
every bit of energy from the wind

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and converting it to pure power.

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This is the power of the wind,
the atmosphere in motion,

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one of the most powerful
and least understood forces on Earth.

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We tend to think of the wind
as chaotic and difficult to predict.

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But when you look
on a much bigger scale,

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at the global picture over time,

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a very different view emerges.

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Weather systems,
and with them the winds,

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follow the same routes around the planet
again and again.

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The discovery of these patterns,

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and sometimes the failure
to understand them,

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lie at the heart of some of the greatest
adventures in human history.

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To see a remarkable example
of how powerful the wind can be

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in changing people's lives,

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I've come to a small town in the middle of
the Sahara Desert called Chinguetti.

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Today, it's almost lost in a sea
of shifting sand dunes,

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but once it was so much more.

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There's a timelessness about this.

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Some of the buildings
are over 7OO years old.

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There's only a few thousand people
live here now,

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but in its heyday,
this place heaved with 2O,OOO people.

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And twice as many camels!

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Hidden away down the back streets
of this crumbling town,

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there's a reminder
of Chinguetti's glorious past.

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- Bonjour.
- Ah, bonjour.

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- Ca va tres bien?
- Ca va, ca va.

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The Al Ahmad Mahmoud Library

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has been run by the same family
for over 3oo years

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and contains hundreds
of ancient manuscripts.

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What is the oldest...?
Plus ancien livre?

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Ah. Le plus ancien livre chez moi...

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- (LAUGHS) It's in a shoebox!
- Ah.

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It's not hermetically sealed.

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- (SPEAKS FRENCH)
- Oh, wow.

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Look at that.

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Ah. What is this?

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Ca, c'est le plus vieux Coran
en Afrique de l'Ouest.

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It's the oldest Koran in West Africa?

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Dixieme siecle.

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It dates back to the 1 Oth century.

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Oh, look, the writing's tiny.

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This priceless book is one of thousands
stored in dozens of libraries

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throughout Chinguetti.

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Ca, c'est les arabesques.

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Arabesque, yeah, yeah.
The colour is beautiful.

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Chinguetti's glory days
were over 5oo years ago,

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and it owed its existence
as a thriving town to the wind.

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Chinguetti is in the heart
of the Sahara.

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It's a barren, inhospitable wilderness.

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The largest desert on the planet.

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Ah.

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Look at that.

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It just goes on and on.

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The Sahara is so hostile that
crossing it is dangerous and difficult.

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Searing heat, no water,
immense distances.

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It's effectively a climate barrier.

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(WIND HOWLING)

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Well, there's another reason why deserts
and dunes are so hard to cross,

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and that is,
they simply don't stand still.

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They are constantly on the move.

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In fact, these are some of the most
dynamic and rapidly changing landscapes

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on Earth.

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(COUGHS)

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There are few reliable landmarks,

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so following a route across the desert
is incredibly hard.

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But it's not only the shifting sand
that's controlled by the wind.

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The entire Sahara Desert itself was
created by large-scale wind movements.

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These winds begin at the equator.

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This is where the sun is at its hottest,
so the air is continually rising.

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As it spreads away from the equator,
it cools,

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until between about
2o and 3o degrees latitude,

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the air sinks back to Earth,
heating up again in the process.

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This pattern of winds creates a band
of hot, dry deserts around the world

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on either side of the equator,

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including the Sahara and Arabian
deserts.

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In an era when travelling
was done by foot,

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the desert was a formidable barrier.

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For most of human history,

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different corners of the world
have evolved as if in parallel universes,

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hemmed in not just by
mountains and oceans,

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but by the desert
that made climate a barrier too.

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But about 1,ooo years ago, nomads were
forging routes through the Sahara.

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Chinguetti was an oasis town
along one of these routes.

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To the south was gold and ivory.

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To the north, the markets of Europe.

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Chinguetti's fortune was made

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because it was a gateway
connecting two worlds

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that were separated
by the power of the wind.

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But this city's great days didn't last.

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The winds that created the
desert barrier had brought it riches.

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But ironically, its decline
was also due to the wind.

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In one short period,
about 5oo years ago,

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the world was entirely remade,

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transforming the fate of people
around the globe.

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And it was all down to a pivotal discovery
about how the winds work.

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This is the Gold Coast in Ghana,
on the west coast of Africa.

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Today, it's dominated
by bustling fishing ports.

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Everyone's got piles of fish!

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But in the 1 5th century, it was
an important centre for the gold trade.

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Europeans began to trade with
the rich empires of West Africa,

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and the Portuguese built this fort,
Elmina,

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to protect their commercial interests.

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And you could say it was here that
the remaking of the world began.

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You know, if you'd been
looking out from this spot in 1 482,

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you'd have seen a Portuguese ship
hove into view

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carrying materials to build this fort.

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On board was a man who would end up
inadvertently changing the destiny

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of this whole region.

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And he did that not with
swords and with cannons,

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but with a discovery about how
the Earth's atmosphere worked.

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He also happened to discover
a new continent.

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His name? Cristoforo Colombo.

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Christopher Columbus
visited these shores

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at an important moment
in European history.

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In the 1 5th century,

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the nations of Europe were competing
to find quicker, easier routes

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to the riches of Asia.

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Christopher Columbus
was a man with a plan,

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because he reckoned he knew
a shortcut route to the Far East.

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As he'd been sailing
up and down this coast,

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he'd been keeping
a close eye on the winds.

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Now, the West African coast juts out
into the Atlantic,

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so sailors here were sometimes
forced into the open ocean.

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Columbus realised that out there,
among the rolling waves,

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the winds seemed to be always blowing
in the same direction -

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away from Africa.

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Columbus reckoned he could use that wind
to blow him all the way round the world.

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Columbus had no way of knowing

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whether the wind he'd encountered along
the West African coast would carry on

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or peter out, leaving him stranded
in the middle of the ocean.

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But in 1 492, he headed west
into the apparently endless ocean

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in search of his new route
to the Far East.

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It's hard to appreciate today

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just what an epic leap into the unknown
this voyage was.

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It took five tough weeks,

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but as we all know,
Columbus's hunch was right -

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there was a wind that blew
right across the Atlantic.

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The thing is, his grasp of sailing was
much better than his grasp of geography.

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It wasn't the Far East he'd landed in.
It was the Bahamas.

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As far as Europeans were concerned,
he'd discovered a new continent,

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and for that, his name is known
throughout the world.

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Yet for me, America wasn't
his greatest discovery.

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Columbus's real genius
was his instinctive understanding

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of the way the winds blow
across the Atlantic.

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He had discovered what we now call
the trade winds -

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winds that blow steadily
in a south-westerly direction.

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It was the trade winds that took him
all the way from the African coast

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to the Bahamas.

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Getting across the Atlantic
was all well and good,

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but now Columbus had to
find his way back home.

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And that was going to be tricky,

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because if he just tried
to retrace his steps east,

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then that would carry him
straight into the wind

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that brought him here
in the first place.

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Instead, Columbus headed north,
along the American coast,

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and here he picked up another wind

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that blew consistently in the
opposite direction, from west to east -

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what's known as a westerly.

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At the time, it must have seemed he was
just outrageously lucky with the winds.

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But luck had nothing to do with it.

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To prove the point, Columbus sailed
back to America three more times.

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Each time, he found the same winds.

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00:17:08,829 --> 00:17:13,983
Between 2o and 3o degrees latitude,
the wind blew east to west.

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Between 4o and 5o degrees,
it blew in the opposite direction.

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00:17:19,789 --> 00:17:24,260
You know, Columbus was wrong
about the continent he'd discovered,

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00:17:24,309 --> 00:17:27,142
but he was right about
something far more important -

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00:17:27,189 --> 00:17:30,420
how to repeatedly use
the circulation of the atmosphere

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to cross the Atlantic Ocean
and get safely home.

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00:17:38,389 --> 00:17:42,860
Today, we know that the trade winds
and westerlies that Columbus exploited

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00:17:42,909 --> 00:17:45,218
are part of one system,

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00:17:45,269 --> 00:17:51,504
the same atmospheric circulation
that creates deserts over continents.

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00:17:51,549 --> 00:17:56,498
At the surface, the descending air
flows back towards the equator.

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00:17:56,549 --> 00:17:59,507
These are the trade winds.

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00:17:59,549 --> 00:18:05,067
They close the loop and form
what's known as an atmospheric cell.

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00:18:05,109 --> 00:18:08,181
It's the spin of the Earth
that deflects these surface winds

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00:18:08,229 --> 00:18:10,459
so that they move towards the Americas.

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00:18:12,749 --> 00:18:17,027
Each hemisphere has
three giant atmospheric cells

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00:18:17,069 --> 00:18:21,665
which define the prevailing
surface winds around the entire Earth.

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00:18:27,509 --> 00:18:31,218
Once people knew about
the prevailing wind patterns,

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00:18:31,269 --> 00:18:35,308
it spurred them on to set sail
for other new lands.

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00:18:37,389 --> 00:18:43,658
The fate of nations now depended on
where they lay in relation to the winds.

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00:18:45,469 --> 00:18:48,461
The Dutch connected with the westerlies in
the Southern Hemisphere

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00:18:48,509 --> 00:18:49,988
to reach the Far East

217
00:18:50,029 --> 00:18:52,668
and ended up in control
of the Dutch East Indies,

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00:18:52,709 --> 00:18:55,177
or Indonesia, as it's now known.

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00:18:55,229 --> 00:18:58,062
The trade winds took them home.

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In the Atlantic,

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00:19:01,909 --> 00:19:05,948
Columbus's voyage formed the basis
for a triangular trade route,

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00:19:05,989 --> 00:19:10,346
connecting Europe, Africa
and the Americas for the first time.

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00:19:12,309 --> 00:19:15,665
The Spanish crossed the Pacific
using the easterly trade winds,

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00:19:15,709 --> 00:19:18,621
so their ships made landfall
at the Philippines,

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00:19:18,669 --> 00:19:21,422
which became a Spanish colony.

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00:19:21,469 --> 00:19:24,700
To get home, the Spanish
picked up the westerlies,

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00:19:24,749 --> 00:19:29,186
bypassing Japan,
which preserved its isolation,

228
00:19:29,229 --> 00:19:32,062
and landed in California.

229
00:19:35,829 --> 00:19:39,378
Now, you can still see the legacy of
that distant Spanish influence

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00:19:39,429 --> 00:19:42,307
in the names that are
so familiar to us today.

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00:19:45,389 --> 00:19:46,788
San Diego,

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00:19:46,829 --> 00:19:49,024
Los Angeles

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00:19:49,069 --> 00:19:50,707
and San Francisco.

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00:19:53,469 --> 00:19:57,144
Within 1 5o years of Columbus's voyage,

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00:19:57,189 --> 00:20:01,228
a network of trade routes
had spread out across the world.

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00:20:01,269 --> 00:20:04,784
It was the start of globalisation.

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00:20:09,229 --> 00:20:15,145
For Europeans, the conquest
of the winds and waves was a triumph.

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00:20:15,189 --> 00:20:17,259
But there was a terrible price.

239
00:20:17,309 --> 00:20:22,429
Many other civilisations were devastated
by European contact.

240
00:20:24,629 --> 00:20:29,384
Perhaps the biggest impact was here,
back in Ghana.

241
00:20:29,429 --> 00:20:32,182
And you can trace
those changing fortunes

242
00:20:32,229 --> 00:20:34,379
in the story of the Elmina fort.

243
00:20:39,269 --> 00:20:44,662
By the early 1 5OOs, the function of this
trading fort had changed dramatically.

244
00:20:44,709 --> 00:20:47,860
Gone was the bartering
for ivory and gold,

245
00:20:47,909 --> 00:20:50,139
and instead the storerooms here

246
00:20:50,189 --> 00:20:53,579
were swollen with a very different kind
of commodity.

247
00:20:58,789 --> 00:21:03,146
These dark cellars had once contained the
stock for the gold trade.

248
00:21:09,509 --> 00:21:15,778
Now the fort of Elmina had become
a staging post for the slave trade.

249
00:21:18,429 --> 00:21:20,863
You know, it's really ugly
to think of this place

250
00:21:20,909 --> 00:21:23,503
as a storeroom for gold and ivory
and all these beautiful riches

251
00:21:23,549 --> 00:21:29,419
and then, just within a few years,
changed into a prison.

252
00:21:36,149 --> 00:21:37,946
While Europe boomed,

253
00:21:37,989 --> 00:21:41,743
Africa's place in the world
had been changed for ever.

254
00:21:50,509 --> 00:21:53,785
It looks like a way out,
and in a perverse kind of way, it was.

255
00:21:53,829 --> 00:21:56,741
Because after spending
a couple of months locked up in the cells,

256
00:21:56,789 --> 00:22:00,338
you'd be taken down this
long, low passageway to this -

257
00:22:00,389 --> 00:22:04,223
a gate barely one person wide.

258
00:22:04,269 --> 00:22:07,500
This was the door of no return,

259
00:22:07,549 --> 00:22:12,384
because when you left here,
blinking into that sharp African light,

260
00:22:12,429 --> 00:22:15,546
probably completely unaware
of what your fate was,

261
00:22:15,589 --> 00:22:20,982
you'd go onto a gangplank and you'd
be shipped to the Americas as slaves.

262
00:22:31,149 --> 00:22:34,858
In the 4oo years after
Columbus made his epic voyage,

263
00:22:34,909 --> 00:22:39,187
nearly 1 2 million slaves
were shipped across the Atlantic.

264
00:22:44,349 --> 00:22:49,548
The impact of new ocean trade routes
even reached as far as Chinguetti,

265
00:22:49,589 --> 00:22:51,580
in the Sahara.

266
00:22:51,629 --> 00:22:55,861
Sailing ships now bypassed
the old desert trade routes,

267
00:22:55,909 --> 00:22:57,945
so the town was eclipsed

268
00:22:57,989 --> 00:23:03,347
by human exploitation of the very winds
that had made it great.

269
00:23:15,109 --> 00:23:19,500
The atmospheric cells are the framework
for winds around the planet.

270
00:23:19,549 --> 00:23:23,178
But there's another global wind
that influences the climate,

271
00:23:23,229 --> 00:23:26,619
and with it,
the course of human history.

272
00:23:26,669 --> 00:23:30,344
High in the atmosphere
are giant conductors

273
00:23:30,389 --> 00:23:34,143
that orchestrate weather patterns
around the world.

274
00:23:34,189 --> 00:23:36,419
They're called jet streams.

275
00:23:39,109 --> 00:23:42,465
Jet streams are powerful currents
of fast-moving wind

276
00:23:42,509 --> 00:23:45,387
that whip along the boundary
between two cells.

277
00:23:47,149 --> 00:23:52,018
They're several hundred kilometres wide
but only a few kilometres thick.

278
00:23:55,269 --> 00:23:58,466
They snake around the globe
in wavy loops,

279
00:23:58,509 --> 00:24:01,626
directing the course
of weather systems below.

280
00:24:05,749 --> 00:24:08,058
We're only really aware
of their significance

281
00:24:08,109 --> 00:24:10,623
when they stray from their normal path.

282
00:24:12,229 --> 00:24:15,107
If the jet stream strays southward,

283
00:24:15,149 --> 00:24:18,505
it can send deadly tornadoes
across Florida,

284
00:24:18,549 --> 00:24:20,540
far from their usual route to the north.

285
00:24:20,589 --> 00:24:25,185
In 1 998,
a jet stream wandered off course

286
00:24:25,229 --> 00:24:30,223
and sent a devastating ice storm across
north-eastern America,

287
00:24:30,269 --> 00:24:35,946
leaving 45 people dead and forcing
hundreds of thousands from their homes.

288
00:24:40,349 --> 00:24:45,628
But perhaps the most catastrophic example
of the power of the jet stream

289
00:24:45,669 --> 00:24:50,618
was on the High Plains
of the United States in the 1 93os.

290
00:24:51,709 --> 00:24:55,748
Today, towns like Capa in South Dakota

291
00:24:55,789 --> 00:24:57,507
lie empty and abandoned.

292
00:25:02,149 --> 00:25:06,267
But in the early part of the century,

293
00:25:06,309 --> 00:25:08,379
farmers were rushing here
to claim new land.

294
00:25:11,029 --> 00:25:14,988
Then, in the 1 93os, disaster struck.

295
00:25:22,029 --> 00:25:25,101
Powerful winds, intense drought

296
00:25:25,149 --> 00:25:28,266
and dense, choking dust storms.

297
00:25:28,309 --> 00:25:32,860
It became known as the Dust Bowl.

298
00:25:40,989 --> 00:25:44,504
Millions of acres of farmland
turned to wasteland.

299
00:25:45,949 --> 00:25:49,305
Half a million people were
uprooted from their homes.

300
00:25:51,349 --> 00:25:53,738
Most never returned.

301
00:25:55,229 --> 00:25:58,380
At the time, it seemed like
a freak accident,

302
00:25:58,429 --> 00:26:01,466
but we now know that the jet stream
was the trigger.

303
00:26:01,509 --> 00:26:04,660
For several years, it had drifted hundreds
of kilometres south

304
00:26:04,709 --> 00:26:06,506
from its normal course,

305
00:26:06,549 --> 00:26:08,346
taking the rains with it.

306
00:26:20,629 --> 00:26:24,542
The jet stream controls the short-term
patterns of wind and weather

307
00:26:24,589 --> 00:26:26,864
across the world.

308
00:26:36,469 --> 00:26:39,939
But perhaps the most significant way
that the wind has affected history

309
00:26:39,989 --> 00:26:43,777
is by defining the climate and character
of entire continents

310
00:26:43,829 --> 00:26:46,104
over thousands of years,

311
00:26:46,149 --> 00:26:49,505
imposing limitations for people
in some parts of the world,

312
00:26:49,549 --> 00:26:53,019
and for others,
offering huge opportunities.

313
00:26:55,269 --> 00:26:56,748
Take China.

314
00:27:09,709 --> 00:27:12,781
Today, China has become
a world superpower.

315
00:27:16,509 --> 00:27:20,980
But China's civilisation
is one of the oldest in the world,

316
00:27:21,029 --> 00:27:25,386
and its success was built on
something delivered by the wind.

317
00:27:31,309 --> 00:27:33,539
This is central China.

318
00:27:33,589 --> 00:27:36,865
It's known as the cradle
of Chinese civilisation,

319
00:27:36,909 --> 00:27:38,979
because this is where

320
00:27:39,029 --> 00:27:41,463
the wealth and power of
China's ancient dynasties began.

321
00:27:46,709 --> 00:27:51,499
High above the Yellow River
is what made it all possible.

322
00:28:00,149 --> 00:28:04,381
A resource that was the key
to China's earliest beginnings.

323
00:28:12,069 --> 00:28:16,540
This plateau was the foundation stone
for China's ancient agriculture.

324
00:28:16,589 --> 00:28:19,422
But what made it that
wasn't a stone at all.

325
00:28:19,469 --> 00:28:21,027
It's what's under my feet.

326
00:28:21,069 --> 00:28:24,857
It's soft and crumbly.

327
00:28:24,909 --> 00:28:26,945
When you crunch it,
it just turns to dust,

328
00:28:26,989 --> 00:28:31,665
which is exactly what it is,
except it's called loess.

329
00:28:34,509 --> 00:28:36,739
This dust is rich in minerals

330
00:28:36,789 --> 00:28:41,579
and combines with rotten plant matter
to form a light, fertile soil.

331
00:28:45,029 --> 00:28:48,544
Chinese farmers settled here
more than 1 o,ooo years ago,

332
00:28:48,589 --> 00:28:52,741
and it was the first sites
of rice cultivation in the world.

333
00:28:55,909 --> 00:29:00,619
And the reason all this loess is here
is because of the winds.

334
00:29:04,469 --> 00:29:09,862
5o million years ago,
India collided with Asia,

335
00:29:09,909 --> 00:29:13,345
and that pushed up the Himalayas.

336
00:29:13,389 --> 00:29:18,827
These mountains created
a completely new pattern of winds.

337
00:29:18,869 --> 00:29:24,865
The Himalayas are so high that air
is forced up, forming clouds and rain.

338
00:29:24,909 --> 00:29:28,026
But when the wind reaches
the far side of the Himalayas,

339
00:29:28,069 --> 00:29:29,582
it's bone dry.

340
00:29:33,749 --> 00:29:36,741
It's called a rain shadow,

341
00:29:36,789 --> 00:29:40,907
and it forms some of the driest
and dustiest places on Earth -

342
00:29:40,949 --> 00:29:44,225
the Taklamakan and the Gobi deserts.

343
00:29:50,629 --> 00:29:54,941
So China is surrounded
by giant reserves of dust,

344
00:29:54,989 --> 00:29:58,902
and the prevailing winds act like
a huge conveyor belt

345
00:29:58,949 --> 00:30:01,622
that blows it all the way
to central China.

346
00:30:05,709 --> 00:30:08,143
Because the plateau is so vast,

347
00:30:08,189 --> 00:30:11,818
farming could develop here
on an enormous scale.

348
00:30:11,869 --> 00:30:14,224
That meant surplus food,

349
00:30:14,269 --> 00:30:18,387
and surplus food is the first
and most important prerequisite

350
00:30:18,429 --> 00:30:20,659
for any self-respecting empire.

351
00:30:23,349 --> 00:30:25,419
Over 3,ooo years ago,

352
00:30:25,469 --> 00:30:29,303
the first of China's famous
dynastic empires was formed.

353
00:30:31,629 --> 00:30:34,939
It was based in the centre
of the loess plateau.

354
00:30:36,269 --> 00:30:41,297
The Great Wall of China was built
across the northern edge of the plateau

355
00:30:41,349 --> 00:30:43,544
to safeguard the empire's heartland.

356
00:31:05,589 --> 00:31:08,342
The importance of the loess plateau

357
00:31:08,389 --> 00:31:11,586
has also shaped China's
cultural heritage.

358
00:31:18,029 --> 00:31:23,661
In the 5th century, they built these -
the Buddhist temples at Yungang.

359
00:31:23,709 --> 00:31:26,701
Carved into solid rock
beneath the layer of loess

360
00:31:26,749 --> 00:31:31,106
is a honeycomb of 25o man-made caves,

361
00:31:31,149 --> 00:31:36,223
the walls covered with over
5o,ooo Buddhist statues.

362
00:31:44,189 --> 00:31:48,660
But the crowning glory
of the loess plateau is this.

363
00:31:53,869 --> 00:31:57,498
The 8,ooo-strong Terracotta Army.

364
00:32:00,749 --> 00:32:03,627
Not only are they buried in the loess,

365
00:32:03,669 --> 00:32:06,979
the terracotta from which
they were created

366
00:32:07,029 --> 00:32:09,463
is itself made from loess.

367
00:32:16,309 --> 00:32:22,259
So what began with loess led to empires
and dynasties, art and religion,

368
00:32:22,309 --> 00:32:25,585
and it was all made possible
by the winds.

369
00:32:32,669 --> 00:32:34,421
China was lucky.

370
00:32:34,469 --> 00:32:37,142
It found itself at the end
of a wind pattern

371
00:32:37,189 --> 00:32:40,898
that delivered some of
the finest-quality soil in the world.

372
00:32:47,269 --> 00:32:49,578
Not everywhere was so fortunate.

373
00:33:01,189 --> 00:33:06,547
Perhaps no continent on Earth has been
more limited by the wind than Australia.

374
00:33:13,469 --> 00:33:17,428
Nothing quite prepares you for the
sheer scale of the Australian outback.

375
00:33:17,469 --> 00:33:19,903
It's very, very barren.

376
00:33:21,749 --> 00:33:24,058
I wouldn't like to be a farmer out here.

377
00:33:26,189 --> 00:33:28,623
It's also amazingly dusty.
I can feel it.

378
00:33:28,669 --> 00:33:31,388
Bitter taste in my mouth.

379
00:33:34,189 --> 00:33:38,819
Australia's Red Centre couldn't be
a harsher place to live.

380
00:33:38,869 --> 00:33:40,746
If it wasn't for the odd shrub,

381
00:33:40,789 --> 00:33:43,303
it could be mistaken
for the surface of Mars.

382
00:33:44,509 --> 00:33:45,988
But at this watering hole

383
00:33:46,029 --> 00:33:50,068
there are signs that people
settled here a very long time ago.

384
00:33:54,469 --> 00:33:58,348
Carvings up to 3o,ooo years old.

385
00:34:00,229 --> 00:34:03,665
And well-crafted stone tools as well.

386
00:34:07,709 --> 00:34:09,381
Flat, round stones like these

387
00:34:09,429 --> 00:34:12,387
were used for grinding up
millet seeds and tubers.

388
00:34:12,429 --> 00:34:16,388
It's a very similar technology
as that used by the first farmers

389
00:34:16,429 --> 00:34:18,385
in Asia and the Middle East.

390
00:34:18,429 --> 00:34:22,741
You know, it's fascinating to think why
this didn't lead to the type of farming

391
00:34:22,789 --> 00:34:24,666
that emerged elsewhere.

392
00:34:26,389 --> 00:34:28,266
About 1 o,ooo years ago,

393
00:34:28,309 --> 00:34:31,619
the development of agriculture
on other continents

394
00:34:31,669 --> 00:34:35,628
led to complex, large-scale societies.

395
00:34:35,669 --> 00:34:39,947
But here, farming never really took off.

396
00:34:39,989 --> 00:34:42,947
You might think that's because
it's parched and dry.

397
00:34:44,349 --> 00:34:47,580
But it's just as much
to do with the wind.

398
00:34:54,629 --> 00:34:58,258
Here you can see the effects of the wind
down at ground level.

399
00:34:58,309 --> 00:35:00,140
Now, what you'd normally expect to find

400
00:35:00,189 --> 00:35:02,419
is a kind of mixture
of sand, gravel and clay,

401
00:35:02,469 --> 00:35:05,905
all jumbled up with plant debris
to give us soil.

402
00:35:05,949 --> 00:35:09,908
Instead, here you get something
that looks rather bizarre.

403
00:35:09,949 --> 00:35:14,625
You can see a kind of mosaic
of larger fragments,

404
00:35:14,669 --> 00:35:17,024
where the finer stuff's just been
blown away by the wind.

405
00:35:17,069 --> 00:35:20,903
And what it produces
is an armoured cap to the land surface -

406
00:35:20,949 --> 00:35:24,066
what we call a desert pavement.

407
00:35:26,789 --> 00:35:30,304
This crust makes it very difficult
for plants to grow.

408
00:35:32,469 --> 00:35:35,506
It isn't just a localised problem.

409
00:35:35,549 --> 00:35:40,828
The winds strip dust and soil away
across much of the continent.

410
00:35:40,869 --> 00:35:43,542
So, what causes this stripping action?

411
00:35:45,269 --> 00:35:51,105
To understand the answer, you need to be
in the centre of the continent

412
00:35:51,149 --> 00:35:52,821
and you need to get up high.

413
00:36:03,189 --> 00:36:09,264
This tabletop mountain is called Attila,
also known as Mount Conner.

414
00:36:09,309 --> 00:36:13,746
It's a huge natural monument
right in the centre of Australia.

415
00:36:29,629 --> 00:36:31,301
(CHUCKLES)

416
00:36:31,349 --> 00:36:33,465
Oh, that makes it all worth it.

417
00:36:33,509 --> 00:36:35,340
Look at that.

418
00:36:35,389 --> 00:36:37,539
That's a hell of a view.

419
00:36:37,589 --> 00:36:39,068
Whoo!

420
00:36:40,829 --> 00:36:43,662
You know, when you're down there,
it's just so flat.

421
00:36:43,709 --> 00:36:48,385
You don't get a sense
of the sheer scale of this landscape.

422
00:36:48,429 --> 00:36:53,139
It's only being up high that you can just
see how...how big it is.

423
00:36:55,749 --> 00:36:57,421
You also appreciate from here

424
00:36:57,469 --> 00:37:01,303
that for the people that had this
landscape, being so precious to them,

425
00:37:01,349 --> 00:37:03,226
that being able to get up here,

426
00:37:03,269 --> 00:37:06,659
and seeing the land laid out
almost like a map,

427
00:37:06,709 --> 00:37:10,384
must have made these high places
just so special.

428
00:37:17,949 --> 00:37:22,943
Mount Conner sits at the geographical
and spiritual heart of Australia.

429
00:37:24,349 --> 00:37:28,900
But it also lies at the centre
of an amazing wind system.

430
00:37:33,989 --> 00:37:37,823
The incredible thing about the atmosphere
above central Australia

431
00:37:37,869 --> 00:37:40,781
is that there's a giant
circular wind pattern

432
00:37:40,829 --> 00:37:43,548
thousands of feet above my head.

433
00:38:02,709 --> 00:38:06,497
The prevailing winds swirl
in a great anticlockwise spiral

434
00:38:06,549 --> 00:38:08,301
around the continent.

435
00:38:12,749 --> 00:38:15,058
They've been stripping the fertility
from the soil

436
00:38:15,109 --> 00:38:17,862
for hundreds of thousands of years.

437
00:38:23,429 --> 00:38:26,944
In China,
fertility was carried in by the wind.

438
00:38:26,989 --> 00:38:32,586
But here in Australia, fertile dust
and nutrients were simply blown away,

439
00:38:32,629 --> 00:38:35,189
leaving sand and stones behind.

440
00:38:37,949 --> 00:38:41,658
The sand has been shaped into
vast fields of dunes,

441
00:38:41,709 --> 00:38:47,067
which circle the centre of Australia,
lined up with the path of the winds.

442
00:38:52,589 --> 00:38:55,786
It's a process
that continues to this day.

443
00:38:57,309 --> 00:39:01,018
Giant dust storms
regularly engulf eastern Australia.

444
00:39:05,029 --> 00:39:11,946
In 2oo2, the largest ever recorded
was more than 2,ooo kilometres long.

445
00:39:15,349 --> 00:39:21,504
Nearly 5 million tons of dust
were removed in just this one storm.

446
00:39:23,269 --> 00:39:28,707
Most of it ends up in the ocean, where its
nutrients create huge algal blooms,

447
00:39:28,749 --> 00:39:31,661
an essential part
of the marine food chain.

448
00:39:39,349 --> 00:39:41,817
So the climate and the winds
dealt a tough hand

449
00:39:41,869 --> 00:39:44,144
to the ancient Aboriginal peoples.

450
00:39:47,509 --> 00:39:51,058
With large areas of the continent
bare and arid,

451
00:39:51,109 --> 00:39:55,580
continuing with the hunter-gatherer
lifestyle made more sense

452
00:39:55,629 --> 00:39:57,824
than taking up farming.

453
00:40:01,629 --> 00:40:05,907
You know, you realise that the people here
were ingenious and adaptable.

454
00:40:05,949 --> 00:40:10,625
For a start, rather than relying
on one or two intensive crops,

455
00:40:10,669 --> 00:40:15,504
they instead diversified into
a wide range of wild food sources.

456
00:40:15,549 --> 00:40:19,781
And also, instead of living
in permanent, settled communities,

457
00:40:19,829 --> 00:40:22,582
they lived instead
in small, mobile groups,

458
00:40:22,629 --> 00:40:26,144
always able to move in search of food.

459
00:40:30,909 --> 00:40:33,867
The differing fate
of Australia and China

460
00:40:33,909 --> 00:40:37,424
is down to large-scale wind patterns
over continents

461
00:40:37,469 --> 00:40:40,142
that are stable over thousands of years.

462
00:40:43,469 --> 00:40:48,020
But the wind has had some of its most
dramatic effects on human history

463
00:40:48,069 --> 00:40:51,778
when it interacts
with the energy of the oceans.

464
00:40:54,309 --> 00:40:59,588
It's an interaction that can have
major long-term consequences,

465
00:40:59,629 --> 00:41:03,304
but it can also bring
short-term disaster.

466
00:41:03,349 --> 00:41:07,262
The sea acts as an immense store
of the sun's heat.

467
00:41:07,309 --> 00:41:11,063
There's more energy
in the top 3 metres of the ocean

468
00:41:11,109 --> 00:41:15,819
than the whole of the atmosphere -
enough to power America for 5o years.

469
00:41:20,189 --> 00:41:23,226
By pumping this energy into the air,

470
00:41:23,269 --> 00:41:26,579
the ocean is constantly
influencing the wind...

471
00:41:28,549 --> 00:41:33,100
...a principle that is graphically
demonstrated each year.

472
00:41:45,389 --> 00:41:48,301
Hurricanes are the most extreme storms
on Earth,

473
00:41:48,349 --> 00:41:51,819
the ultimate example
of the violent partnership

474
00:41:51,869 --> 00:41:54,508
between the atmosphere and the ocean.

475
00:41:54,549 --> 00:41:58,508
The hotter the ocean,
the faster the air above rises,

476
00:41:58,549 --> 00:42:01,825
drawing the wind inwards
in a vicious spiral.

477
00:42:01,869 --> 00:42:04,463
Each 1 degree rise in sea temperature

478
00:42:04,509 --> 00:42:09,822
increases wind speeds
by more than 2o kilometres per hour.

479
00:42:09,869 --> 00:42:12,667
Around the eye of the hurricane,

480
00:42:12,709 --> 00:42:15,507
the clouds build up
like the inside of a stadium,

481
00:42:15,549 --> 00:42:20,020
leaving a calm centre
around which the winds rotate.

482
00:42:28,189 --> 00:42:33,138
It's the spin of the Earth that gives
a hurricane its distinctive spiral shape.

483
00:42:39,029 --> 00:42:42,226
And as they move
across the surface of the globe,

484
00:42:42,269 --> 00:42:45,898
hurricanes are caught up
in the same atmospheric circulation

485
00:42:45,949 --> 00:42:48,782
that drives the trade winds
and westerlies.

486
00:42:48,829 --> 00:42:51,901
Their tracks cluster
in bands of destruction

487
00:42:51,949 --> 00:42:54,258
on either side of the equator.

488
00:42:59,909 --> 00:43:01,945
Devastating as hurricanes are,

489
00:43:01,989 --> 00:43:06,699
on a planetary scale, their effects
are relatively minor and short-lived.

490
00:43:09,549 --> 00:43:12,017
But it turns out
that the ocean affects winds

491
00:43:12,069 --> 00:43:15,539
over much larger areas
and longer timescales,

492
00:43:15,589 --> 00:43:18,945
and that discovery
has answered a great puzzle

493
00:43:18,989 --> 00:43:22,425
in the story of the human conquest
of the globe.

494
00:43:26,629 --> 00:43:30,304
The Pacific is the largest ocean
on Earth.

495
00:43:30,349 --> 00:43:33,785
The only land is a scattering
of tiny islands,

496
00:43:33,829 --> 00:43:36,866
some of the most inaccessible places
on the planet.

497
00:43:41,149 --> 00:43:45,859
Ever since modern humans left Africa
several tens of thousands of years ago,

498
00:43:45,909 --> 00:43:49,584
our distant ancestors
have spread across the continents.

499
00:43:51,949 --> 00:43:57,262
But there's always been a bit of a gap -
the Pacific Ocean.

500
00:43:59,749 --> 00:44:03,662
Long after the rest of the planet
was colonised by humans,

501
00:44:03,709 --> 00:44:06,303
the Pacific lay empty.

502
00:44:08,749 --> 00:44:11,183
With its scattering of tiny islands,

503
00:44:11,229 --> 00:44:15,586
it's little wonder that the Pacific
remained unexplored for so long.

504
00:44:15,629 --> 00:44:19,304
If you were a would-be explorer
heading out into the unknown,

505
00:44:19,349 --> 00:44:22,227
the chances are
you'd run out of food or water

506
00:44:22,269 --> 00:44:26,581
long before you reached
the next tropical paradise.

507
00:44:34,949 --> 00:44:39,625
Then,just over 3,ooo years ago,
sailors set off from Asia

508
00:44:39,669 --> 00:44:43,503
and began to spread to nearly
every island in this vast ocean,

509
00:44:43,549 --> 00:44:46,268
ending up in the distant,
far-flung islands

510
00:44:46,309 --> 00:44:50,461
of Hawaii, New Zealand
and Easter Island.

511
00:44:50,509 --> 00:44:54,661
It was a journey that took them
a quarter of the way around the world.

512
00:45:00,909 --> 00:45:05,061
You know, it's not just the distances
that people travelled that amazes me,

513
00:45:05,109 --> 00:45:06,940
it's also the direction.

514
00:45:06,989 --> 00:45:12,017
This is my crummy map of the Pacific.
Here's Asia over here, with Japan.

515
00:45:12,069 --> 00:45:15,778
This is supposed to be the Americas here.
Australia down here.

516
00:45:15,829 --> 00:45:19,868
It's thought that this whole area was
peopled by going from west to east,

517
00:45:19,909 --> 00:45:22,787
but the thing is, in this region,
the winds blow in the opposite direction -

518
00:45:22,829 --> 00:45:24,945
from east to west.

519
00:45:24,989 --> 00:45:28,026
Trying to sail into the wind
from such long distances

520
00:45:28,069 --> 00:45:30,503
would have taken a lifetime.

521
00:45:30,549 --> 00:45:33,985
So quite how they did this
has always been a big mystery.

522
00:45:36,869 --> 00:45:42,102
The answer lies in that turbulent link
between the atmosphere and the ocean,

523
00:45:42,149 --> 00:45:46,461
and the best place to see it in action
is in the middle of the Pacific.

524
00:45:50,269 --> 00:45:52,578
An island like Yap.

525
00:45:53,709 --> 00:45:56,428
A tiny dot of dense rainforest

526
00:45:56,469 --> 00:45:59,745
over 1,ooo kilometres
from the nearest continent.

527
00:46:02,949 --> 00:46:08,421
The question is,
how did people get to islands like Yap

528
00:46:08,469 --> 00:46:11,063
and then move on
to the other islands of the Pacific

529
00:46:11,109 --> 00:46:14,226
when they were heading
into the prevailing winds

530
00:46:14,269 --> 00:46:19,741
and all they had were these -
wooden outrigger canoes?

531
00:46:21,749 --> 00:46:23,626
(TRUMPETS)

532
00:46:42,669 --> 00:46:45,502
These boats have barely changed

533
00:46:45,549 --> 00:46:49,224
since the first sailors set off
across the Pacific.

534
00:46:54,549 --> 00:46:59,145
So how did they sail
across the entire ocean against the wind?

535
00:47:02,829 --> 00:47:06,617
Normally, sailing into the wind
would involve taking a zigzag route

536
00:47:06,669 --> 00:47:08,944
called tacking.

537
00:47:11,789 --> 00:47:14,223
The problem with
sailing into the wind is this -

538
00:47:14,269 --> 00:47:16,464
you keep needing to tack all the time,

539
00:47:16,509 --> 00:47:18,943
which means you need to move
the sail from the front to the back

540
00:47:18,989 --> 00:47:21,662
by swinging the mast and the boom round,

541
00:47:21,709 --> 00:47:24,177
so that the front of the boat
becomes the back.

542
00:47:24,229 --> 00:47:28,620
And then... It's actually quite tricky
and quite dangerous.

543
00:47:33,549 --> 00:47:37,747
By moving this sail
from the front of the boat to the back,

544
00:47:37,789 --> 00:47:43,341
these canoes can indeed tack
back and forth across the wind,

545
00:47:43,389 --> 00:47:45,141
gradually moving forward.

546
00:47:46,829 --> 00:47:49,707
But it's a slow and difficult process.

547
00:47:51,949 --> 00:47:54,179
It's good? Yeah?

548
00:47:54,229 --> 00:47:55,901
I always get slightly nervous.

549
00:47:55,949 --> 00:47:59,988
For you, thousands of times.
For me, this looks dangerous.

550
00:48:00,029 --> 00:48:03,339
Ali Haleyalur is the chief navigator.

551
00:48:05,429 --> 00:48:10,583
So in the past, when your predecessors
made lots of long journeys,

552
00:48:10,629 --> 00:48:12,620
how did they do that against the wind?

553
00:48:13,669 --> 00:48:15,944
If it's really far,
it's not safe to go east,

554
00:48:15,989 --> 00:48:21,302
because within that four or five days
that you tack in it,

555
00:48:21,349 --> 00:48:23,340
you still cannot arrive,

556
00:48:23,389 --> 00:48:25,664
and then another storm hits you there.

557
00:48:25,709 --> 00:48:29,338
So it's better you have to wait
when the westerly wind comes.

558
00:48:31,149 --> 00:48:34,459
There are always short periods
when the wind blows from the west

559
00:48:34,509 --> 00:48:36,101
due to seasonal changes,

560
00:48:36,149 --> 00:48:40,108
but not long enough
to undertake long voyages.

561
00:48:40,149 --> 00:48:43,107
But the ancient navigators realised

562
00:48:43,149 --> 00:48:46,505
that there are certain times
when the winds change direction

563
00:48:46,549 --> 00:48:50,542
and blow consistently for long periods
from west to east.

564
00:48:52,429 --> 00:48:55,068
The secret of this change
lies in the relationship

565
00:48:55,109 --> 00:48:57,942
between the Pacific Ocean and the winds.

566
00:49:02,629 --> 00:49:06,508
Every few years,
warm water from the west Pacific

567
00:49:06,549 --> 00:49:09,382
surges into the cooler waters
of the east.

568
00:49:09,429 --> 00:49:13,741
This warm water heats the air above,
changing air pressure

569
00:49:13,789 --> 00:49:17,941
and making the trade winds weaken
or swap directions completely.

570
00:49:21,829 --> 00:49:26,107
Today we know this phenomenon
as El Nino.

571
00:49:27,589 --> 00:49:32,743
These changes over the Pacific
have a huge impact on the weather...

572
00:49:34,909 --> 00:49:39,221
...causing flash floods
on the American continent.

573
00:49:41,749 --> 00:49:46,300
Meanwhile, in places as far apart
as Australia and Africa,

574
00:49:46,349 --> 00:49:50,228
temperatures soar, causing wildfires.

575
00:49:57,189 --> 00:50:02,343
But for the ancient Pacific colonisers,
it would have transformed their options.

576
00:50:02,389 --> 00:50:06,064
With the wind blowing consistently
from west to east,

577
00:50:06,109 --> 00:50:09,306
the exploration of the Pacific
would have been much easier.

578
00:50:10,749 --> 00:50:13,263
So what happens to the winds
during El Nino years?

579
00:50:13,309 --> 00:50:18,258
I realised that
during the El Nino years,

580
00:50:18,309 --> 00:50:22,700
the wind is extended very long
and very strong.

581
00:50:22,749 --> 00:50:28,699
It remains coming from the west.
That's what I see during that time.

582
00:50:28,749 --> 00:50:31,183
So the westerlies stay for longer.

583
00:50:31,229 --> 00:50:33,697
- Yeah, kind of stay for a longer time.
- Right.

584
00:50:37,589 --> 00:50:42,788
And this may be the key to the mystery
of how the Pacific was colonised.

585
00:50:42,829 --> 00:50:46,583
El Ninos tend to come in phases.

586
00:50:46,629 --> 00:50:48,460
It now seems that in the past,

587
00:50:48,509 --> 00:50:53,867
each El Nino phase coincided with a wave
of colonisation across the Pacific.

588
00:50:56,589 --> 00:51:00,264
And so the most epicjourneys
in history,

589
00:51:00,309 --> 00:51:04,587
journeys that took people to the most
far-flung corners of the world,

590
00:51:04,629 --> 00:51:09,020
were at least partly the result
of how the ocean affects the winds.

591
00:51:14,069 --> 00:51:16,867
It would be nice to think
that the ocean and winds

592
00:51:16,909 --> 00:51:22,700
always had positive effects on history.
But the reality is more complex,

593
00:51:22,749 --> 00:51:27,584
because El Nino is just one phase
in a larger climatic system

594
00:51:27,629 --> 00:51:29,506
called the Southern Oscillation.

595
00:51:30,669 --> 00:51:34,628
This oscillation in the Pacific
is so powerful

596
00:51:34,669 --> 00:51:40,699
that it's had profound effects on
civilisations across much of the planet.

597
00:51:45,829 --> 00:51:50,266
Chaco Canyon in the south-west corner
of the USA,

598
00:51:50,309 --> 00:51:54,939
once home to a people
who built a sophisticated civilisation.

599
00:52:01,149 --> 00:52:03,219
Oh, wow! Look at that.

600
00:52:03,269 --> 00:52:05,260
She's beautiful.

601
00:52:05,309 --> 00:52:07,186
That is so big!

602
00:52:07,229 --> 00:52:09,868
I mean, that's what really strikes you -
this is a big landscape,

603
00:52:09,909 --> 00:52:11,865
and still this jumps out at you.

604
00:52:11,909 --> 00:52:16,778
You can just tell that
this place was built to last.

605
00:52:16,829 --> 00:52:21,619
It looks like the people here figured
they'd be here for a very long time.

606
00:52:24,109 --> 00:52:26,987
At the heart of the canyon
are the remains of a structure

607
00:52:27,029 --> 00:52:28,667
called a ''great house''.

608
00:52:30,189 --> 00:52:32,066
Pueblo Bonito.

609
00:52:40,149 --> 00:52:45,701
It was built by the Anasazi
over 1,ooo years ago.

610
00:52:52,229 --> 00:52:54,584
Ooh!

611
00:52:54,629 --> 00:52:57,268
Must have been
a wee bit smaller than me!

612
00:52:57,309 --> 00:53:01,302
Pueblo Bonito was the centre
of the Anasazi civilisation.

613
00:53:01,349 --> 00:53:07,299
Thousands of people lived nearby
in the surrounding farms and villages.

614
00:53:12,149 --> 00:53:14,788
You know, there's a good reason
why the people at Chaco Canyon

615
00:53:14,829 --> 00:53:17,548
built their settlements
at the base of these massive cliffs,

616
00:53:17,589 --> 00:53:20,467
and that's because
the water is from up there.

617
00:53:20,509 --> 00:53:23,148
There's hardly any rainfall around here,

618
00:53:23,189 --> 00:53:27,819
but the rain that does fall lands on the
mesa behind here, runs off into ravines

619
00:53:27,869 --> 00:53:31,748
and then comes cascading down
into the valley.

620
00:53:44,149 --> 00:53:46,458
Rather than let it drain off
into the river,

621
00:53:46,509 --> 00:53:50,218
the Anasazi would build
dams and channels to pool the water

622
00:53:50,269 --> 00:53:52,908
or to divert it off
to where it was needed.

623
00:53:59,149 --> 00:54:04,177
But by 1 3OO, this whole region
had become effectively deserted,

624
00:54:04,229 --> 00:54:07,221
and the big question was why.

625
00:54:14,749 --> 00:54:18,344
The answer lay
thousands of kilometres away.

626
00:54:18,389 --> 00:54:22,541
Unknown to them, they were at the mercy
of the Southern Oscillation

627
00:54:22,589 --> 00:54:24,181
in the distant Pacific Ocean.

628
00:54:31,149 --> 00:54:35,267
When unusually warm water moves
to the west of the Pacific,

629
00:54:35,309 --> 00:54:37,027
it changes the winds,

630
00:54:37,069 --> 00:54:40,744
taking rain and storms
away from the Americas

631
00:54:40,789 --> 00:54:43,622
and leaving communities inland
parched.

632
00:54:57,029 --> 00:55:00,465
Normally, this isn't enough
to have a lasting impact,

633
00:55:00,509 --> 00:55:05,867
but around 1 3oo AD,
the climate got stuck in this phase,

634
00:55:05,909 --> 00:55:09,822
leading to a series of mega droughts
lasting decades.

635
00:55:14,349 --> 00:55:18,388
It wasn't just the Anasazi civilisation
that was affected.

636
00:55:18,429 --> 00:55:21,739
Each time the Southern Oscillation
got stuck in this position,

637
00:55:21,789 --> 00:55:25,702
the result was a similarly
devastating mega drought.

638
00:55:29,549 --> 00:55:33,258
The Fremont, Mogollon
and Hohokam cultures

639
00:55:33,309 --> 00:55:37,302
all declined at the same time
as the Anasazi.

640
00:55:38,909 --> 00:55:43,380
In South America,
the Tiwanaku and the Sican,

641
00:55:43,429 --> 00:55:46,785
and in Central America,
the Toltecs and the Zapotecs

642
00:55:46,829 --> 00:55:48,467
were all weakened or collapsed

643
00:55:48,509 --> 00:55:51,421
because of changes
in the Southern Oscillation.

644
00:55:52,869 --> 00:55:54,985
And droughts caused
by the Southern Oscillation

645
00:55:55,029 --> 00:56:00,581
also brought to a close the first era
of the mighty Mayan empire.

646
00:56:04,469 --> 00:56:07,108
Severe droughts weren't the only factor

647
00:56:07,149 --> 00:56:09,902
behind the collapse
of these civilisations.

648
00:56:12,829 --> 00:56:18,665
At Chaco Canyon, the people were living
close to the limits of their resources,

649
00:56:18,709 --> 00:56:22,543
so they were highly vulnerable
to climatic changes.

650
00:56:26,269 --> 00:56:30,547
For me, that's a message
that still resonates today.

651
00:56:38,789 --> 00:56:43,783
The impact of the winds on human history
has been subtle and often unseen,

652
00:56:43,829 --> 00:56:46,468
but extraordinarily powerful.

653
00:56:47,949 --> 00:56:51,385
They define climate zones
that, for thousands of years,

654
00:56:51,429 --> 00:56:56,219
set the limits for human development
over much of the world.

655
00:57:03,109 --> 00:57:09,298
Then, paradoxically,
the winds set us free from these limits.

656
00:57:11,669 --> 00:57:15,662
Now, as our climate is changing,

657
00:57:15,709 --> 00:57:19,304
we can expect significant changes
in wind patterns,

658
00:57:19,349 --> 00:57:24,218
altering the distribution
of heat and moisture around the world.

659
00:57:25,469 --> 00:57:30,384
How we cope will depend on
how close we are to our own limits.

660
00:57:36,309 --> 00:57:38,664
Whether it's on land or at sea,

661
00:57:38,709 --> 00:57:43,908
we've gained so much by exploiting
and adapting to the rhythms of the wind.

662
00:57:43,949 --> 00:57:46,304
But we've never really mastered it.

663
00:57:46,349 --> 00:57:48,988
We can only ever be one step behind.

664
00:57:49,029 --> 00:57:50,508
I mean, even today,

665
00:57:50,549 --> 00:57:54,588
when we can virtually track every twist
and turn of the air above our head,

666
00:57:54,629 --> 00:57:57,746
the atmosphere is still mysterious,
still erratic

667
00:57:57,789 --> 00:58:01,384
and ultimately still shapes our future.

668
00:58:03,869 --> 00:58:05,666
Next time - fire.

669
00:58:05,709 --> 00:58:06,858
Oh!

670
00:58:06,909 --> 00:58:11,903
It's deadly and yet it's also the power
behind human progress.

671
00:58:11,949 --> 00:58:16,659
Our dependence on fire
means that events deep in the Earth's past

672
00:58:16,709 --> 00:58:19,177
have changed the course
of human history.

673
00:58:19,229 --> 00:58:21,379
Ah...