"perhaps none has greater power over us than water." "water's the most magical force on Earth." "renews and nourishes our planet." "my gosh!" "You're getting all wet there!" "It's our planet's lifeblood. delivering vital ingredients for life." "it's glorious." "Water makes Earth alive." "Yet water is just one of the ways that the power of the planet has shaped our lives." "The Earth has immense power and yet that's rarely mentioned in our history books." "I'm here to change that." "I'm exploring four great planetary forces that have influenced our history." "The power of the deep Earth that fuelled technological innovation." "Wind." "It has shaped the fate of entire continents." "And fire which gave us the power to conquer the planet." "But I'm going to start with water. shifting between guises and from place to place." "Our struggle to control it has been behind the rise and fall of some of the greatest civilisations on Earth." "The centre of the Sahara Desert in North Africa." "One of the driest places on Earth." "I'm over six hours' drive from civilisation. and there's less than a centimetre of rainfall each year." "Ah...." "The whole thing's moving." "It's like walking on water." "Yet hidden amongst these dry dunes are clues that point to the dramatic influence the planet has had on human lives. the story of this place is all about water." "The clues are etched into that rock face there. and depicting the most unlikely cast of characters you've ever seen." "what is that?" "It's a giraffe... there's the neck. and its mouth." "isn't it? drinking some water - we've got a herd of giraffes here!" "There's two cats." "They're fighting." "This..." "What is this?" "but he's wearing a bikini." "which is especially odd here." "it doesn't just paddle around. all the creatures that are depicted on these rocks are not desert animals - they need wet conditions." "how can this be?" "this place was wet." "the evidence is all around. and it's been carved by running water and then cascaded down into the valley and off there." "that was a big river." "Satellite images reveal that the river bed I'm standing in is just one of a network of past river valleys that crisscross the Sahara Desert." "empty place was entirely different. but we do know that they depended entirely on water." "Water formed the lakes in which they swam." "Water nourished the plants which fed the animals they hunted." "Water filled the clay pots from which they drank." "But then the climate changed." "the Sahara began to dry." "and the lakes dried out." "For the early Saharan people there was only one option - to follow the rains and abandon the desert." "The fortunes of the early Saharan people timeless truth - our fate is inextricably linked to water." "water never stands still." "It's always on the move across the planet." "We think of this as a blue planet." "most of it is no use." "which we can't drink or use to grow crops." "on which all human life hangs. because fresh water has a life cycle all of its own." "in all its elusive glory." "doesn't it?" "But to see its remarkable qualities you have to go to some extreme lengths." "Here we go..." "Ho-ho!" "Feel that!" "Ride Of The Valkyries" "Here we go!" "we're off!" "my God!" "It's a bit bouncy!" "I shouldn't have had that bacon and eggs this morning." "O-o-o-h!" "The fresh water that we depend on begins its life in the oceans. they heat the water molecules until some evaporate." "It's the start of an extraordinary journey. it feels as if it vanishes into thin air. water molecules are suspended around us all the time." "It's just that we're only aware of it when they clump together as cloud." "less than a thousandth of the world's fresh water is up here in the atmosphere." "but this is what spreads water from the seas to the land." "A water molecule doesn't hang around up here for very long." "it spends less time up here in the atmosphere than at any other time on its journey - a mere nine days until the typical water molecule crashes to Earth as rain." "rain is perhaps but notoriously the least reliable. cascading and carving its way across the land surface as streams and rivers." "Look at that!" "Water absolutely everywhere!" "Rivers and rain are the part of the water cycle that we depend on." "Whoo-hoo!" "And yet they.re only a tiny proportion of the world's fresh water a measly 2% of all fresh water on the planet." "The rest of the Earth's fresh water on the ground." "Oh..." "Oh!" "What a landing!" "The vast majority of it is stored as ice. where it's known as groundwater." "Hidden away down here is the planet's second-largest store of fresh water. and the cycle begins again." "What that circulation means for us humans is that water is a moving target." "We constantly have to seek it out on its endless cycle and intercept it wherever and whenever we can." "This quest to... to pin down water has played a defining role in human history." "You can trace the impact of our quest for water 000 years ago." "It all began with a big block of ice. huge ice sheet." "And even today you can see its legacy here in Iceland." "This glacier is a tiny remnant of that once enormous expanse of ice. a store into which water can be deposited or withdrawn." "And it was a shift in the amount of water locked up here that was to drive one of the greatest ever transformations of human society. and releasing this great armada of icebergs. it's a very different story. sucking moisture out of the atmosphere in vast quantities" "and locking it away in the ice." "And the effects of that were felt right across the planet." "Thousands of kilometres away in the Middle East it led to a drought which lasted for centuries." "It had its most profound impact in what would become known an area famed for its exceptionally rich soil." "This drought would trigger the start of the defining characteristic of human civilisation." "every human on the planet was a hunter-gatherer." "thrived on rich pickings with plenty of deer and ibex to hunt." "to survive they would have to adapt." "They came up with two distinct strategies. state-of-the-art arrowhead that allowed them to tackle a drought by hunting more efficiently." "But a second group came up with something a little bit more subtle. and it offered a completely new approach to gathering food." "stone blade represented but to stay put and grow it." "The Harif point did a good job for the hunters." "But it was the sickle that really changed history. but that decision to remain in one place meant planting crops was essential. you can collect far more food. these people had begun the agricultural revolution." "is history." "A lack of water and a simple but ingenious response led to the birth of civilisation." "it had a profound impact on our relationship with water." "No longer could we simply follow the rains." "reliable sources of water to make sure their crops grew." "So the need for water began to define where the first civilisations could flourish." "That led people to the one stage of the water cycle that offers reliable fresh water - rivers. they became magnets." "But rivers did more than supply a steady source of water." "They changed the very character of the civilisations influencing everything from politics to social organisation." "The power of rivers to shape history is graphically illustrated by perhaps the greatest of all early civilisations Ancient Egypt." "You might think you know the story - a mighty civilisation that built the pyramids under the autocratic rule of ruthless Pharaohs. you have to leave the pyramids and the temples behind... to a small place that hardly anyone visits. 000-year-old steps." "But this staircase is what made Ancient Egypt tick." "You get an idea of its true purpose by the markings on the side wall - these grooves were carefully carved into the marble - because this was a beautifully simple measuring device." "you have to pop round the corner." "Oh!" "It's all wet!" "And this is it - the Nile river." "That set of steps and markings is a Nilometer." "It measured the changing level of the river." "the maximum height that the waters came to would directly predict the yield of the crops the profits that the farmers made." "It worked because the water of the river carried something special within it - an almost invisible treasure that was the secret of Egypt's economic might." "What made Egypt great is this stuff - silt." "which..." "It's like an espresso." "Tiny flecks of rock and minerals that the river picked up over its wandering course and swept along with the flow. where the rock is young and volcanic." "This forms the richest of silts." "140 million tonnes of the stuff are carried by the Nile down river to Egypt each year." "the seasonal flood covered the fields and left behind nutrient-rich silt that fertilised the crops." "the more food was produced." "It was the size of the flood - and with it the bounty of silt - that the Nilometer was used to predict." "the Egyptians were able the profits of the farmers." "they used this information to set tax levels." "So the wealth and the might and the splendour of Ancient Egypt is all down to a simple twist of geographical fate." "Ethiopia itself gets almost no benefit from that fertile soil washed from its highlands." "It's even said that its greatest export is the silt silt that made the Pharaohs rich." "But the ebb and flow of the Nile had more far-reaching implications for the Egyptian people than mere taxes. that actually determines the way a society is organised and even its use of slavery." "Where water is in short supply - as it is in Egypt - then you need a highly structured society to get the best out of it." "you need bureaucrats to decide where to dig the water channels." "really - to do the actual hard work of digging." "you need farmers with money enough to buy the water it's delivered. and I haven't even mentioned the Pharaohs." "hierarchical structure of Egyptian society wasn't just dictated by the Pharaohs." "It also emerged because the Egyptians had only one water source - the Nile. it wasn't just the Ancient Egyptians who noticed the value of rivers." "Other great civilisations were also forming along the banks of rivers. the Sumerian civilisation flourished between the Tigris and the Euphrates." "the Harappan civilisation formed by the Indus." "And early Chinese civilisations were emerging along the Yellow River." "But not all early farmers were content to settle by rivers. in the unlikeliest places." "in Libya. 500 years ago was the centre of a powerful empire." "but from up here the way the streets interconnect." "You get a real sense of how this place must have worked in its prime." "This was the home of the Garamantians... are a rather forgotten people. the Greeks and the Romans." "000 years." "They were the society that first brought civilisation to the desert. the Garamantes were flourishing." "They grew crops such as cereals and grapes." "They kept horses and pigs." "they needed large amounts of water." "here in the middle of the desert?" "this is the key to the Garamantians' incredible success." "It's vertical holes that are sunk deep into the ground 40 to 50 metres - that's about 150 feet." "And the purpose of them was pretty simple - it was to bring water up from below ground." "it must have seemed like it was almost magic." "the Garamantians had discovered groundwater." "Beneath the surface of the Sahara is a surprising part of the great water cycle - a massive store of groundwater." "This is water that has seeped into the ground and has collected in porous layers of rock." "The water came from the period when the Sahara was lush and wet. despite the dramatic drying above until the Garamantes found it." "You kind of dig them down until you hit the water table and then you just keep doing the same thing." "all in a whole line." "But these holes aren't wells - they.re maintenance shafts." "They reach down to tunnels which carried the water. down to the kind of oasis over there." "that's where the Garamantians' city was." "What they could have done is they could have dug wells down but that's a lot of work for very little return." "Much better to use gravity to channel the water in an underground tunnel straight to where they need it." "That was the Garamantians' real ingenuity." "The Garamantes had managed to tap the same water that the early Saharans had enjoyed thousands of years earlier." "the Garamantians managed to turn the clock back on the Sahara - they made the desert bloom again." "But the human struggle to pin down water is forever balanced on a knife edge." "Get that balance wrong and you pay the price." "the Garamantes over-exploited their groundwater." "and so did their civilisation." "Now all that remains are the bats. by using pumps to reach deeper than the Garamantes could." "they.re exploiting a finite resource." "it will last only another 50 years." "But water in this most inaccessible stage of the water cycle is found in many other places." "in Florida." "divers are just beginning to explore a mysterious series of caves carved out by groundwater over millions of years." "This is one of the planet's least known frontiers." "these divers had no idea of the extent of the cave network. travelling more than ten kilometres from the cave entrance." "They.re sometimes underwater for 24 hours at a time." "Their efforts have revealed one of the world's largest underwater cave systems. that underlies all of Florida and reaches into neighbouring states." "And it's not just the USA." "There's groundwater in the most unexpected places." "More than 30% of all the fresh water on Earth is under our feet." "our apparently solid planet is more like a sponge. the need for reliable supplies of water led us to rivers and groundwater." "they learned to exploit the vagaries of the water cycle in many different ways." "The key was adaptation." "Take rain." "A familiar occurrence in many parts of the world." "But this is rain at its most extreme - the monsoon." "The significance of the monsoon isn't the human discomfort but how the people here have learned to live with it. which holds the world record for the highest rainfall in a single year." "I thought I knew rain. it's different rain." "It's hard to explain." "It's the sheer intensity of it - it just comes barrelling down." "the raindrops are massive. you're just soaked." "It's pointless with a hood and all the rest of it" " I'm soaked." "like this chap." "Very wet!" "Wet." "it's very slidy." "the average annual rainfall the annual average rainfall is more than ten times that - between 11 and 12 metres." "That's nearly the height of a four-storey building." "and rivers turn to torrents." "you have to adapt... just to get around." "And that's exactly what the local Khasi people have done." "Look at this!" "Isn't this fantastic?" "Look at it!" "you can see all these roots coming down." "The texture of them is beautiful." "this entire structure is built of growing rubber tree." "It's just mad when you follow it!" "You can see that this is the perfect union of the tree and the villagers. knitted them together." "What they've done here is they've grabbed some rootlets like this here it is... this set of rootlets here." "That's incredibly strong." "It's an anchor for the bridge." "Ordinary bridges would rot under the relentless drenching of the monsoon." "What's clever about these root bridges is they get stronger as they get older." "a whole village could get through here." "the intensity of the monsoon rain is all down to a basic property of water." "water takes a lot of energy to heat up." "So the land and the ocean react very differently to the rising temperatures of early summer." "India's land surface heats up much more than the surrounding Indian Ocean. creating low pressure. which brings rain." "It's because the whole system is driven by the sun's heat that the rains come in the summer." "But it also means that the monsoon only lasts for three months of the year." "there's virtually no rain. to these extremes of the monsoon." "I think it's this way." "you have to use your elbows in here." "But outsiders are not always so sensitive to its rhythms." "the changing strength of the monsoon year on year had really tremendous impacts on the country's political fortunes. the story of which was played out against a backdrop of water abundance and scarcity." "Clearly there are lots of reasons to explain the fate but one of the least explored and most intriguing is water." "the failure of the British to manage India's water supply had significant consequences... for them and for the Indian people. but the British never really got to grips with the monsoon." "people here have been developing ways to deal with the monsoon." "And this was one of the most important - it's a huge open well that was dug down deep enough to reach groundwater." "the water was filtered through the surrounding ground and held in the well like a gigantic bucket. were more than water collectors." "The genius of this design was it turned the mundane need for water into a social ritual. they even worshipped." "up until the 19th century." "they were the main source of water." "Despite the fact that structures like this helped the Indian people the British didn't like it." "They were concerned that people bathing in the same water they drank from was bad news." "they shut them down. they imported another problem much worse. 000 kilometres of them - perhaps their biggest engineering achievement anywhere. these huge bodies of standing water were a health hazard - the perfect environment for malaria to breed and spread. it's perhaps ironic that the monsoon played a significant role" "in undermining British rule in India." "the monsoon rains failed." "there were repeated droughts." "and there were terrible famines." "But the British failed to respond effectively - they even continued to export rice." "This indifference to the rhythms of the monsoon fuelled popular anger and the independence movement grew rapidly." "the step wells are being repaired." "Pumps accessing groundwater are used to protect against the unreliable monsoon." "And that's made India the largest user of groundwater in the world." "Adapting to the water cycle has meant the difference between success and failure for many civilisations." "But there was another strategy that also brought success and that was to take control of the water cycle." "There was one early civilisation above all others that took control of the planet's most dramatically changing source of water." "They mastered the monsoon. they dominated the area we now know as Cambodia." "And this was their greatest achievement... the legendary temple complex of Angkor. 200 years ago." "you can see it's showing the age. that looks as if it could have been carved just yesterday." "Angkor was built to honour the Hindu gods and it symbolised the extraordinary success of the Khmers." "this place is a monument to something else - the Khmers' ability to harness the power of the monsoon." "The Khmers were first drawn to this region by the Tonle Sap lake and the river that feeds it. replete with all the necessary amenities." "All life here is lived on the river - everything." "A hardware store! or just chilling out." "People settle here today for the same reason 000 years ago - the unusual behaviour of the lake around monsoon time." "the land around here swells enormously. the largest freshwater lake in Southeast Asia." "the water brings with it a spectacular bounty." "nibbling away at your toes in this murky water." "the Tonle Sap lake becomes the richest source of freshwater fish in the world." "the Khmers realised that this annual influx of fish and water offered a glittering opportunity. they built the temples of Angkor." "the Khmer kingdom faced a stumbling block." "the fish and water would vanish." "the inhabitants were plunged into drought and hunger." "The Khmer rose to the challenge magnificently. they would make it work for them." "This is part of a vast network of irrigation tunnels that crisscross the whole of Angkor. people had seen nothing like them." "This was plumbing on a grand scale." "it's still visible today." "the Khmers managed to divert a river by 80 kilometres." "They built canals 000 square kilometres and dug reservoirs that could hold up to 600 million cubic metres of monsoon water." "the Khmers seized control of the planet's water cycle. all-year-round water supply." "enabling Angkor at its peak to support a population in excess of one million. the Khmers had built the largest pre-industrial city in the world. which was when the kingdom of Angkor finally went to the wall." "They were victims of their own success. including - despite all that incredible engineering - including the water supply." "I guess that there are limits to what even the mighty monsoon can sustain." "we control water on a massive scale." "000 cubic kilometres of water." "That's five times as much water as in all the rivers on Earth. the extra weight has slightly changed how the Earth spins on its axis. shortening the day by 8 millionths of a second in the last 40 years." "we take our control of water for granted." "Modern civilisation couldn't exist without it." "But there's still only a finite amount of water to go around. scarcity has led to a bitter struggle for control over the available supply." "And that's true in even the wealthiest countries." "Los Angeles is a city with every luxury and convenience." "Los Angeles was struggling." "hemmed in on three sides by desert and on the fourth by ocean." "So it lacked the most basic requirement for city life - a reliable water supply." "So it came up with a plan to get the water it so needed. was a place called Owens Valley." "where people were settling and building farms." "At the heart of it was plentiful water - a wide river feeding a huge lake." "This valley must have seemed like the answer to Los Angeles' prayers." "There was enough water here to easily supply over one million people." "There was only one problem... it didn't belong to them." "It belonged to the farmers of Owens Valley." "It would have to be taken by stealth. masquerading as investors. just to get the water rights that went with it." "but it was certainly shady." "And it worked. an aqueduct was opened." "And this is it. certainly as far as Los Angeles was concerned." "It allowed millions of people 200 miles down there to live in a growing and vibrant city." "But that's not how people here saw it." "The Owens Valley farmers didn't give up without a struggle. allowing the water to pour back down into Owens Valley." "And regularly they'd dynamite the aqueduct. and a game of cat and mouse continued for three more dynamite-filled years. and the rebellion fizzled out." "The city had won." "the Los Angeles Aqueduct is just part of a giant network of pipes and aqueducts all serving one of the world's great cities. and the river is barely a trickle." "The story of Owens Valley is not an isolated case." "there are conflicts over water taking place all around the world." "Syria and Jordan dispute access to the River Jordan." "Sudan and Ethiopia quarrel over the waters of the Nile." "India and Pakistan are in conflict over dams built on the river's tributaries." "And these are only some of the more well-known examples." "we lived at the whim of the unpredictable water cycle." "we have harnessed the power of rivers to advance our civilisations." "We have extracted groundwater from the depths of the most unlikely places." "And we have learned to redirect and store water on a massive scale." "we have unprecedented power over the planet's water." "But one thing hasn't changed - there's still only a finite amount of water on Earth." "It seems to me that water is the Achilles heel of our modern civilisation. with the potential to limit our ambitions." "The fundamental limits of the water cycle are still there." "But the lesson of history is that the most successful civilisations learn to adapt to those limits." "So the problem is more with us." "more optimistic." "at least the future's in our hands." "the contradictory role of the deep Earth. but its gifts... came at a price."