"Our planet is full of astonishing natural wonders." "Look at that!" "Oh!" "It has immense power." "that's rarely mentioned in our history books." "I'm here to change that." "I'm looking at four ways that the power of the planet has shaped our history. the source of great technological breakthroughs." "Water... my gosh!" "You're getting all wet there." "...our struggle to control it has directed human progress." "The deep Earth..." "Blooming heck!" "That really is deep." "...that provided the raw materials for our conquest of the planet." "But this time I'm looking at the power of the wind. the wind has shaped the destiny of peoples across the globe." "It has built fortunes and brought ruin." "we.re still at the mercy of the wind. at sea." "this boat is the place to be." "This is one of the fastest sailing boats ever built." "It's capable of up to 50 miles an hour. you can really feel that phenomenal speed." "But what makes this thing really special is when it starts to fly." "Whoo!" "But the real key to this craft's phenomenal breakneck pace is up there. every inch of it grabbing every bit of energy from the wind and converting it to pure power. one of the most powerful and least understood forces on Earth." "We tend to think of the wind as chaotic and difficult to predict. a very different view emerges. follow the same routes around the planet again and again. lie at the heart of some of the greatest adventures in human history." "To see a remarkable example of how powerful the wind can be I've come to a small town in the middle of the Sahara Desert called Chinguetti. but once it was so much more." "There's a timelessness about this." "Some of the buildings are over 700 years old. 000 people." "And twice as many camels! there's a reminder of Chinguetti's glorious past." "bonjour." "ca va." "The Al Ahmad Mahmoud Library has been run by the same family for over 300 years and contains hundreds of ancient manuscripts." "What is the oldest...?" "Plus ancien livre?" "Ah." "Le plus ancien livre chez moi..." " It's in a shoebox!" " Ah." "It's not hermetically sealed." "wow." "Look at that." "Ah." "What is this?" "c'est le plus vieux Coran en Afrique de l'Ouest." "It's the oldest Koran in West Africa?" "Dixieme siecle." "It dates back to the 10th century." "the writing's tiny." "This priceless book is one of thousands stored in dozens of libraries throughout Chinguetti." "c'est les arabesques." "yeah." "The colour is beautiful. and it owed its existence as a thriving town to the wind." "Chinguetti is in the heart of the Sahara." "inhospitable wilderness." "The largest desert on the planet." "Ah." "Look at that." "It just goes on and on." "The Sahara is so hostile that crossing it is dangerous and difficult." "immense distances." "It's effectively a climate barrier. they simply don't stand still." "They are constantly on the move." "these are some of the most dynamic and rapidly changing landscapes on Earth. so following a route across the desert is incredibly hard." "But it's not only the shifting sand that's controlled by the wind." "The entire Sahara Desert itself was created by large-scale wind movements." "These winds begin at the equator." "so the air is continually rising. heating up again in the process." "dry deserts around the world including the Sahara and Arabian deserts. the desert was a formidable barrier. but by the desert that made climate a barrier too." "nomads were forging routes through the Sahara." "Chinguetti was an oasis town along one of these routes." "To the south was gold and ivory." "the markets of Europe." "Chinguetti's fortune was made because it was a gateway connecting two worlds that were separated by the power of the wind." "But this city's great days didn't last." "The winds that created the desert barrier had brought it riches." "its decline was also due to the wind. transforming the fate of people around the globe." "And it was all down to a pivotal discovery about how the winds work." "on the west coast of Africa." "it's dominated by bustling fishing ports." "Everyone's got piles offish!" "it was an important centre for the gold trade. to protect their commercial interests." "And you could say it was here that the remaking of the world began. you'd have seen a Portuguese ship hove into view carrying materials to build this fort." "On board was a man who would end up inadvertently changing the destiny of this whole region. but with a discovery about how the Earth's atmosphere worked." "He also happened to discover a new continent." "His name?" "Cristoforo Colombo." "Christopher Columbus visited these shores at an important moment in European history. easier routes to the riches of Asia. because he reckoned he knew a shortcut route to the Far East. he'd been keeping a close eye on the winds. so sailors here were sometimes forced into the open ocean. the winds seemed to be always blowing in the same direction " "away from Africa." "Columbus reckoned he could use that wind to blow him all the way round the world." "Columbus had no way of knowing whether the wind he'd encountered along the West African coast would carry on leaving him stranded in the middle of the ocean." "he headed west into the apparently endless ocean in search of his new route to the Far East." "It's hard to appreciate today just what an epic leap into the unknown this voyage was." "Columbus's hunch was right - there was a wind that blew right across the Atlantic." "his grasp of sailing was much better than his grasp of geography." "It wasn't the Far East he'd landed in." "It was the Bahamas. his name is known throughout the world." "America wasn't his greatest discovery." "Columbus's real genius was his instinctive understanding of the way the winds blow across the Atlantic." "He had discovered what we now call the trade winds - winds that blow steadily in a south-westerly direction." "It was the trade winds that took him all the way from the African coast to the Bahamas. but now Columbus had to find his way back home. then that would carry him straight into the wind that brought him here in the first place. and here he picked up another wind" "from west to east - what's known as a westerly." "it must have seemed he was just outrageously lucky with the winds." "But luck had nothing to do with it." "Columbus sailed back to America three more times." "he found the same winds." "the wind blew east to west." "it blew in the opposite direction. but he was right about something far more important - how to repeatedly use the circulation of the atmosphere to cross the Atlantic Ocean and get safely home." "we know that the trade winds and westerlies that Columbus exploited the same atmospheric circulation that creates deserts over continents." "the descending air flows back towards the equator." "These are the trade winds." "They close the loop and form what's known as an atmospheric cell." "It's the spin of the Earth that deflects these surface winds so that they move towards the Americas." "Each hemisphere has three giant atmospheric cells which define the prevailing surface winds around the entire Earth. it spurred them on to set sail for other new lands." "The fate of nations now depended on where they lay in relation to the winds." "The Dutch connected with the westerlies in the Southern Hemisphere to reach the Far East as it's now known." "The trade winds took them home." "Africa and the Americas for the first time. which became a Spanish colony. and landed in California." "you can still see the legacy of that distant Spanish influence in the names that are so familiar to us today." "Los Angeles and San Francisco. a network of trade routes had spread out across the world." "It was the start of globalisation." "the conquest of the winds and waves was a triumph." "But there was a terrible price." "Many other civilisations were devastated by European contact." "back in Ghana." "And you can trace those changing fortunes in the story of the Elmina fort." "the function of this trading fort had changed dramatically. and instead the storerooms here were swollen with a very different kind of commodity." "These dark cellars had once contained the stock for the gold trade." "Now the fort of Elmina had become a staging post for the slave trade." "it's really ugly to think of this place as a storeroom for gold and ivory and all these beautiful riches changed into a prison." "Africa's place in the world had been changed for ever." "it was. low passageway to this - a gate barely one person wide. you'd go onto a gangplank and you'd be shipped to the Americas as slaves. nearly 12 million slaves were shipped across the Atlantic. in the Sahara. so the town was eclipsed" "by human exploitation of the very winds that had made it great." "The atmospheric cells are the framework for winds around the planet. the course of human history." "High in the atmosphere are giant conductors that orchestrate weather patterns around the world." "They.re called jet streams." "Jet streams are powerful currents of fast-moving wind that whip along the boundary between two cells." "They.re several hundred kilometres wide but only a few kilometres thick. directing the course of weather systems below." "We.re only really aware of their significance when they stray from their normal path. far from their usual route to the north." "a jet stream wandered off course leaving 45 people dead and forcing hundreds of thousands from their homes." "But perhaps the most catastrophic example of the power of the jet stream was on the High Plains of the United States in the 1930s." "towns like Capa in South Dakota lie empty and abandoned. farmers were rushing here to claim new land." "disaster struck." "intense drought choking dust storms." "It became known as the Dust Bowl." "Millions of acres of farmland turned to wasteland." "Half a million people were uprooted from their homes." "Most never returned. but we now know that the jet stream was the trigger." "it had drifted hundreds of kilometres south taking the rains with it." "The jet stream controls the short-term patterns of wind and weather across the world." "But perhaps the most significant way that the wind has affected history is by defining the climate and character of entire continents offering huge opportunities." "Take China." "China has become a world superpower. and its success was built on something delivered by the wind." "This is central China. because this is where the wealth and power of China's ancient dynasties began." "High above the Yellow River is what made it all possible." "A resource that was the key to China's earliest beginnings." "This plateau was the foundation stone for China's ancient agriculture." "But what made it that wasn't a stone at all." "It's what's under my feet." "It's soft and crumbly. except it's called loess." "This dust is rich in minerals fertile soil. and it was the first sites of rice cultivation in the world." "And the reason all this loess is here is because of the winds. and that pushed up the Himalayas." "These mountains created a completely new pattern of winds." "forming clouds and rain. it's bone dry. and it forms some of the driest and dustiest places on Earth - the Taklamakan and the Gobi deserts. and the prevailing winds act like a huge conveyor belt that blows it all the way to central China. farming could develop here on an enormous scale. and surplus food is the first and most important prerequisite" "for any self-respecting empire. the first of China's famous dynastic empires was formed." "It was based in the centre of the loess plateau." "The Great Wall of China was built across the northern edge of the plateau to safeguard the empire's heartland." "The importance of the loess plateau has also shaped China's cultural heritage." "they built these - the Buddhist temples at Yungang." "Carved into solid rock beneath the layer of loess 000 Buddhist statues." "But the crowning glory of the loess plateau is this." "000-strong Terracotta Army. the terracotta from which they were created is itself made from loess. and it was all made possible by the winds." "China was lucky." "It found itself at the end of a wind pattern that delivered some of the finest-quality soil in the world." "Not everywhere was so fortunate." "Perhaps no continent on Earth has been more limited by the wind than Australia." "Nothing quite prepares you for the sheer scale of the Australian outback." "very barren." "I wouldn't like to be a farmer out here." "It's also amazingly dusty." "I can feel it." "Bitter taste in my mouth." "Australia's Red Centre couldn't be a harsher place to live. it could be mistaken for the surface of Mars." "But at this watering hole there are signs that people settled here a very long time ago." "000 years old." "And well-crafted stone tools as well." "round stones like these were used for grinding up millet seeds and tubers." "It's a very similar technology as that used by the first farmers in Asia and the Middle East." "it's fascinating to think why this didn't lead to the type of farming that emerged elsewhere. the development of agriculture on other continents large-scale societies." "farming never really took off." "You might think that's because it's parched and dry." "But it's just as much to do with the wind." "Here you can see the effects of the wind down at ground level." "what you'd normally expect to find all jumbled up with plant debris to give us soil." "here you get something that looks rather bizarre. where the finer stuff's just been blown away by the wind." "And what it produces is an armoured cap to the land surface - what we call a desert pavement." "This crust makes it very difficult for plants to grow." "It isn't just a localised problem." "The winds strip dust and soil away across much of the continent." "what causes this stripping action?" "you need to be in the centre of the continent and you need to get up high." "also known as Mount Conner." "It's a huge natural monument right in the centre of Australia." "that makes it all worth it." "Look at that." "That's a hell of a view." "Whoo!" "it's just so flat." "You don't get a sense of the sheer scale of this landscape." "It's only being up high that you can just see how...how big it is." "You also appreciate from here must have made these high places just so special." "Mount Conner sits at the geographical and spiritual heart of Australia." "But it also lies at the centre of an amazing wind system." "The incredible thing about the atmosphere above central Australia is that there's a giant circular wind pattern thousands of feet above my head." "The prevailing winds swirl in a great anticlockwise spiral around the continent." "They.ve been stripping the fertility from the soil for hundreds of thousands of years." "fertility was carried in by the wind. leaving sand and stones behind. lined up with the path of the winds." "It's a process that continues to this day." "Giant dust storms regularly engulf eastern Australia." "000 kilometres long." "Nearly 5 million tons of dust were removed in just this one storm. an essential part of the marine food chain." "So the climate and the winds dealt a tough hand to the ancient Aboriginal peoples. continuing with the hunter-gatherer lifestyle made more sense than taking up farming." "you realise that the people here were ingenious and adaptable. they instead diversified into a wide range of wild food sources. always able to move in search of food." "The differing fate of Australia and China is down to large-scale wind patterns over continents that are stable over thousands of years." "But the wind has had some of its most dramatic effects on human history when it interacts with the energy of the oceans. but it can also bring short-term disaster." "The sea acts as an immense store of the sun's heat." "There's more energy in the top 3 metres of the ocean than the whole of the atmosphere - enough to power America for 50 years. the ocean is constantly influencing the wind a principle that is graphically demonstrated each year. the ultimate example of the violent partnership" "between the atmosphere and the ocean. drawing the wind inwards in a vicious spiral." "Each 1 degree rise in sea temperature increases wind speeds by more than 20 kilometres per hour. leaving a calm centre around which the winds rotate." "It's the spin of the Earth that gives a hurricane its distinctive spiral shape. hurricanes are caught up in the same atmospheric circulation that drives the trade winds and westerlies." "Their tracks cluster in bands of destruction on either side of the equator. their effects are relatively minor and short-lived." "But it turns out that the ocean affects winds and that discovery has answered a great puzzle in the story of the human conquest of the globe." "The Pacific is the largest ocean on Earth. some of the most inaccessible places on the planet. our distant ancestors have spread across the continents." "But there's always been a bit of a gap - the Pacific Ocean. the Pacific lay empty. it's little wonder that the Pacific remained unexplored for so long. the chances are you'd run out of food or water" "long before you reached the next tropical paradise." "sailors set off from Asia far-flung islands" "New Zealand and Easter Island." "It was a journey that took them a quarter of the way around the world. it's also the direction." "with Japan." "This is supposed to be the Americas here." "Australia down here. the winds blow in the opposite direction - from east to west." "Trying to sail into the wind from such long distances would have taken a lifetime." "So quite how they did this has always been a big mystery. and the best place to see it in action is in the middle of the Pacific." "An island like Yap." "A tiny dot of dense rainforest 000 kilometres from the nearest continent." "how did people get to islands like Yap and then move on to the other islands of the Pacific when they were heading into the prevailing winds and all they had were these - wooden outrigger canoes?" "These boats have barely changed since the first sailors set off across the Pacific." "So how did they sail across the entire ocean against the wind?" "sailing into the wind would involve taking a zigzag route called tacking." "The problem with sailing into the wind is this - which means you need to move the sail from the front to the back so that the front of the boat becomes the back." "And then..." "It's actually quite tricky and quite dangerous. gradually moving forward." "But it's a slow and difficult process." "It's good?" "Yeah?" "I always get slightly nervous." "this looks dangerous." "Ali Haleyalur is the chief navigator. how did they do that against the wind? and then another storm hits you there." "So it's better you have to wait when the westerly wind comes." "There are always short periods when the wind blows from the west but not long enough to undertake long voyages." "But the ancient navigators realised that there are certain times when the winds change direction and blow consistently for long periods from west to east." "The secret of this change lies in the relationship between the Pacific Ocean and the winds." "warm water from the west Pacific surges into the cooler waters of the east." "changing air pressure and making the trade winds weaken or swap directions completely." "Today we know this phenomenon as El Nino." "These changes over the Pacific have a huge impact on the weather causing flash floods on the American continent. causing wildfires." "it would have transformed their options. the exploration of the Pacific would have been much easier." "So what happens to the winds during El Nino years? the wind is extended very long and very strong." "It remains coming from the west." "That's what I see during that time." "So the westerlies stay for longer." "kind of stay for a longer time." " Right." "And this may be the key to the mystery of how the Pacific was colonised." "El Ninos tend to come in phases. each El Nino phase coincided with a wave of colonisation across the Pacific. were at least partly the result of how the ocean affects the winds." "It would be nice to think that the ocean and winds because El Nino is just one phase in a larger climatic system called the Southern Oscillation." "This oscillation in the Pacific is so powerful that it's had profound effects on civilisations across much of the planet. once home to a people who built a sophisticated civilisation." "wow!" "Look at that." "She's beautiful." "That is so big! and still this jumps out at you." "You can just tell that this place was built to last." "It looks like the people here figured they'd be here for a very long time." "At the heart of the canyon are the remains of a structure called a "great house"." "Pueblo Bonito." "000 years ago." "Ooh!" "Must have been a wee bit smaller than me!" "Pueblo Bonito was the centre of the Anasazi civilisation." "Thousands of people lived nearby in the surrounding farms and villages." "there's a good reason why the people at Chaco Canyon and that's because the water is from up there. runs off into ravines and then comes cascading down into the valley. the Anasazi would build dams and channels to pool the water" "or to divert it off to where it was needed. and the big question was why." "The answer lay thousands of kilometres away." "they were at the mercy of the Southern Oscillation in the distant Pacific Ocean. taking rain and storms away from the Americas and leaving communities inland parched. leading to a series of mega droughts lasting decades." "It wasn't just the Anasazi civilisation that was affected. the result was a similarly devastating mega drought." "Mogollon and Hohokam cultures all declined at the same time as the Anasazi. the Toltecs and the Zapotecs were all weakened or collapsed because of changes in the Southern Oscillation." "And droughts caused by the Southern Oscillation also brought to a close the first era of the mighty Mayan empire." "Severe droughts weren't the only factor behind the collapse of these civilisations. so they were highly vulnerable to climatic changes." "that's a message that still resonates today. but extraordinarily powerful. set the limits for human development over much of the world." "the winds set us free from these limits. altering the distribution of heat and moisture around the world." "How we cope will depend on how close we are to our own limits. we've gained so much by exploiting and adapting to the rhythms of the wind." "But we've never really mastered it." "We can only ever be one step behind. still erratic and ultimately still shapes our future." "Next time - fire." "Oh!" "It's deadly and yet it's also the power behind human progress." "Our dependence on fire means that events deep in the Earth's past have changed the course of human history." "Ah..."