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How Earth Made Us -

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(generated from captions) Of all our planet's forces, over us than water. perhaps none has greater power magical force on Earth. For me, water's the most renews and nourishes our planet. The presence of water shapes, You're getting all wet there! Oh, my gosh! It's our planet's lifeblood. It pumps through it continuously, for life. Ah, it's glorious. delivering vital ingredients Water makes Earth alive. Yet water is just one of the ways has shaped our lives. that the power of the planet The Earth has immense power... in our history books. ..and yet that's rarely mentioned I'm here to change that. four great planetary forces In this series, I'm exploring that have influenced our history. The power of the deep Earth... innovation. ..that fuelled technological Wind. of entire continents. It has shaped the fate And fire... to conquer the planet. ..which gave us the power But I'm going to start with water. it's constantly transforming itself, The magic of water is that and from place to place. shifting between guises has been behind the rise and fall Our struggle to control it civilisations on Earth. of some of the greatest in North Africa. The centre of the Sahara Desert One of the driest places on Earth.

from civilisation. I'm over six hours' drive 40 degrees Celsius, Temperatures here regularly reach of rainfall each year. and there's less than a centimetre Ah... The whole thing's moving. (HE STRAINS) It's like walking on water. are clues Yet hidden amongst these dry dunes the planet has had on human lives. that point to the dramatic influence you'd never know it, I've come here because although is all about water. the story of this place into that rock face there. The clues are etched dating back 6,000 years, Prehistoric rock art cast of characters you've ever seen. and depicting the most unlikely Wow, what is that? It's a giraffe... there's the neck. It's a giraffe, look at it, There's its ears, that's an eye, and its mouth. That's really natural, isn't it? dipping its head down, And this looks like the giraffe we've got a herd of giraffes here! drinking some water - There's two cats. They're fighting. This... What is this? but he's wearing a bikini. It looks like the figure of a man, which is especially odd here. And this is clearly a crocodile, it doesn't just paddle around. This is an aquatic animal, In fact, It needs a lot of water to live in. these rocks are not desert animals - all the creatures are depicted on they need wet conditions. how can this be? In such a parched wilderness, 6,000 years ago, this place was wet. The only explanation is that the evidence is all around. Once you know what to look for, that's been carved out into the rock, Up there is a river valley and it's been carved by running water smoothing off this rock bed, which has flowed down here, the valley and off there. and then cascaded down into that was a big river. 6,000 years ago, that the river bed I'm standing in Satellite images reveal of past river valleys is just one of a network that crisscross the Sahara Desert. place was entirely different. 10,000 years ago, this dry, empty Saharans who lived here then, Little is known about the early entirely on water. but we do know that they depended in which they swam. Water formed the lakes which fed the animals they hunted. Water nourished the plants from which they drank. Water filled the clay pots But then the climate changed. the Sahara began to dry. About 5,500 years ago, and the lakes dried out. The rains failed, the rivers shrank, there was only one option - For the early Saharan people and abandon the desert. to follow the rains of the early Saharan people The fortunes reveal a universal, timeless truth - linked to water. our fate is inextricably water never stands still. The problem is, across the planet. It's always on the move We think of this as a blue planet. most of it is no use. But while water is abundant, is salty ocean, which we can't drink More than 97% of the Earth's water or use to grow crops. on which all human life hangs. Less than 3% is fresh water, is often hard to pin down, What's more, that tiny fraction has a life cycle all of its own. because fresh water in all its elusive glory. I'm about to explore that cycle, doesn't it? You know, water seems so familiar, But to see its remarkable qualities to some extreme lengths. you have to go (MOTOR CHUGS INTO LIFE) (REVVING) Here we go... Ho-ho! Feel that! # WAGNER: Ride Of The Valkyries Here we go! Oh... Hey-hey! Oh, we're off! Oh, my God! It's a bit bouncy! that bacon and eggs this morning. I shouldn't have had O-o-o-h! (LAUGHS) begins its life in the oceans. The fresh water that we depend on on the surface of the sea, As the sun's rays beat down until some evaporate. they heat the water molecules of an extraordinary journey. It's the start You know, when water evaporates, into thin air. it feels as if it vanishes But although we barely notice it, around us all the time. water molecules are suspended when they clump together as cloud. It's just that we're only aware of it the world's fresh water is up here At any one time, less than 1,000th of in the atmosphere. the seas to the land. what spreads water from It may not seem much, but this is up here for very long. A water molecule doesn't hang around up here in the atmosphere In fact, it spends less time on its journey - than at any other time a mere nine days crashes to Earth as rain. until the typical water molecule (THUNDER RUMBLES) (BIRD SQUAWKS) For most of us, rain is perhaps of the water cycle, the most familiar stage but notoriously the least reliable. it joins a bigger system, As the water falls as rain, the land surface cascading and carving its way across 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 is locked away down there, on the ground. Oh... (LAUGHING) Oh! What a landing! The vast majority of it is stored as ice. Most of the rest seeps deep into the Earth, where it's known as groundwater. Hidden away down here is the planet's second-largest store of fresh water. But in the end, all water arrives back in the oceans, 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 right back to the dawn of civilisation, about 12,000 years ago. It all began with a big block of ice. 12,000 years ago, much of the northern hemisphere was covered in a single, huge ice sheet. And even today you can see its legacy... in Iceland. This glacier is a tiny remnant of that once enormous expanse of ice. Ice is like a storage cupboard in the circulation of water around the planet, 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. Today, the ice sheet here is melting and retreating, and releasing this great armada of icebergs. But if you go back 12,500 years ago, it's a very different story. Then the ice was expanding, 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... led to a drought which lasted for centuries. It had its most profound impact in what would become known as the Fertile Crescent, an area famed for its exceptionally rich soil. This drought would trigger the start of the defining characteristic of human civilisation. Back then, every human on the planet was a hunter-gatherer. Those living in the Fertile Crescent, the Natufians, thrived on rich pickings of fruit and berries, with plenty of deer and ibex to hunt. But as the drought took hold, to survive they would have to adapt. They came up with two distinct strategies. One group developed this, the Harif point, a new, 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. Although you wouldn't know it, this is a sickle, and it offered a completely new approach to gathering food. This small, stone blade represented a decision not to chase food, 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. In a drought, it's safer to stay close to water, but that decision to remain in one place meant planting crops was essential. If you go foraging in the forest, you can only collect so much food with your bare hands, but if you've got one of these, you can harvest fast and furious, and for the same amount of effort, you can collect far more food. With this simple tool, these people had begun the agricultural revolution. And the rest, as they say, is history. A lack of water and a simple but ingenious response led to the birth of civilisation. But once farming took hold, it had a profound impact on our relationship with water. No longer could we simply follow the rains. Now people needed regular, 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. Across the planet, rivers cover a tiny proportion of the Earth's surface, but for the first farmers, they became magnets. But rivers did more than supply a steady source of water. They changed the very character of the civilisations that grew up along them, 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. But if you want to understand what really made Egypt great, you have to leave the pyramids and the temples behind... ..and come here, to a small place that hardly anyone visits. You know, at first glance these look like your average, everyday, 2,000-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. And to see what it was measuring, 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. Each year when it flooded, the maximum height that the waters came to would directly predict the yield of the crops and, with that, 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. It's a rich soup of minerals, 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. All rivers carry some silt, but the Nile has the benefit of starting in Ethiopia, 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. Every year, the seasonal flood covered the fields and left behind nutrient-rich silt that fertilised the crops. The more silt, 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. So, simply by measuring the height of the Nile, the Egyptians were able to forecast food production and, with it, the profits of the farmers. Each year, 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. In fact, 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 that it sends down the Nile, 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. Intriguingly, it may be that where access to water is limited, that actually determines the way a society is organised and even its use of slavery. Where water is in short supply - or from a single source, as it is in Egypt - then you need a highly structured society to get the best out of it. For large-scale irrigation, you need bureaucrats to decide where to dig the water channels. You need teams of working men - slaves, really - to do the actual hard work of digging. And once the channels are in place, you need farmers with money enough to buy the water it's delivered. So right away you've got three tiers of society, and I haven't even mentioned the Pharaohs. So the rigid, 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. 5,000 years ago, it wasn't just the Ancient Egyptians who noticed the value of rivers. Other great civilisations were also forming along the banks of rivers. In Mesopotamia, the Sumerian civilisation flourished between the Tigris and the Euphrates. Further east, 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. Others learned to exploit new sources of water, in the unlikeliest places. Like the Sahara Desert, in Libya. These are the remains of the ancient city of Garama, which about 2,500 years ago was the centre of a powerful empire. Today, it's a bit of a maze, but from up here you can see the shapes of the buildings, 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... ..which, for me, are a rather forgotten people. They've been eclipsed in the history books by their showy contemporaries, the Greeks and the Romans. The Garamantians dominated the Sahara Desert for almost 2,000 years.

They were the society that first brought civilisation to the desert. Far from just scraping by in this harsh landscape, the Garamantes were flourishing. They grew crops such as cereals and grapes. They kept horses and pigs. Clearly, they needed large amounts of water. So where did they find it, here in the middle of the desert? Now, 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. In this environment, it must have seemed like it was almost magic. In fact, 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 thousands of years before, when the Sahara was lush and wet. Some of that water percolated into the rocks below and remained there, 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. There's one after another, after another, all in a whole line. But these holes aren't wells - they're maintenance shafts. They reach down to tunnels which carried the water. The point is, right up there at the end is where the water source is, so the water flows naturally from the escarpment up there, underground, down to the kind of oasis over there. Now, that's where the Garamantians' city was. What they could have done is they could have dug wells down a lot of work for very little return. and lifted the water out, but that's to channel the water Much better to use gravity straight to where they need it. in an underground tunnel real ingenuity. That was the Garamantians' to tap the same water The Garamantes had managed thousands of years earlier. that the early Saharans had enjoyed

the Garamantians managed By mining groundwater, they made the desert bloom again. on the Sahara - to turn the clock back to pin down water But the human struggle is forever balanced on a knife edge. and you pay the price. Get that balance wrong their groundwater. the Garamantes over-exploited For all their ingenuity, and so did their civilisation. Eventually it ran out, Now all that remains are the bats. (SQUEAKING AND FLUTTERING) Today, modern Libyans have tapped into this same groundwater supply, by using pumps to reach deeper than the Garamantes could. But just like their ancient predecessors, they're exploiting a finite resource. At most, 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 Tallahassee, in Florida. It's at its most spectacular explore a mysterious series of caves Here, divers are just beginning to groundwater over millions of years. called a karst system, carved out by least known frontiers. This is one of the planet's these divers had no idea When they began, of the extent of the cave network. the longest dives in history, To explore these caves, they've made from the cave entrance. travelling more than ten kilometres for 24 hours at a time. They're sometimes underwater

Their efforts have revealed underwater cave systems. one of the world's largest groundwater, of varying depths, It's part of a huge store of neighbouring states. and reaches into that underlies all of Florida 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. Looked at this way, our apparently solid planet is more like a sponge. In our early history, the need for reliable supplies of water led us to rivers and groundwater. But as humans spread across the planet, they learned to exploit in many different ways. the vagaries of the water cycle The key was adaptation. (THUNDER RUMBLES) Take rain. in many parts of the world. A familiar occurrence at its most extreme - But this is rain the monsoon. isn't the human discomfort The significance of the monsoon have learned to live with it. but how the people here of the monsoon, I'm travelling to the very epicentre a place called Cherrapunjee, highest rainfall in a single year. which holds the world record for the (THUNDER RUMBLES) I thought I knew rain. you've met rain before, If you're from the west of Scotland, it's different rain. but this is different, It's the sheer intensity of it - It's hard to explain. it just comes barrelling down. But also, the raindrops are massive. You feel as if you could fill an egg cup with them, which means that, within minutes, you're just soaked. It's pointless with a hood and all the rest of it - I'm soaked. What I really need is a brolly, like this chap. Very wet! Wet. Just watch it, it's very slidy. from, the average annual rainfall Back in west Scotland, where I'm horrify a Californian, is nearly a metre, and that might the annual average rainfall but here in Cherrapunjee, between 11 and 12 metres. is more than ten times that - of a four-storey building. That's nearly the height and rivers turn to torrents. Streams turn to rivers, you have to adapt... When you live with so much water, just to get around. the local Khasi people have done. And that's exactly what Look at this! Isn't this fantastic? Look at it! see all these roots coming down. It's a living bridge - look, you can The texture of them is beautiful. is built of growing rubber tree. I mean, this entire structure It's just mad when you follow it! union of the tree and the villagers. You can see that this is the perfect trained the roots, The locals have kind of knitted them together. kind of guided them through, grabbed some rootlets like this What they've done here is they've And look, here it is... and taken it round. That's incredibly strong. this set of rootlets here. It's an anchor for the bridge. of the monsoon. under the relentless drenching Ordinary bridges would rot as they get older. root bridges is they get stronger What's clever about these could get through here. So wide! I mean, a whole village (THUNDER RUMBLES) of the monsoon rain is all down Surprisingly, the intensity to a basic property of water. takes a lot of energy to heat up. Compared to other substances, water react very differently So the land and the ocean of early summer. to the rising temperatures surface heats up much more During these months, India's land than the surrounding Indian Ocean. reduces the density of the air, The high temperature creating low pressure. onto the land, That sucks moist ocean air 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. For the rest of the time, there's virtually no rain. (TRAIN HOOTER BLARES) The people of India have adapted, as much as they can, to these extremes of the monsoon. I think it's this way. you have to use your elbows in here. It's great, so sensitive to its rhythms. But outsiders are not always of the monsoon year on year Here in India, the changing strength on the country's political fortunes. had really tremendous impacts of its recent colonial past, That's especially true the story of which was played out of water abundance and scarcity. against a backdrop to explain the fate Clearly there are lots of reasons of British colonial rule in India, and most intriguing is water. but one of the least explored In the 19th century, the failure of the British had significant consequences... to manage India's water supply for them and for the Indian people. it was because they were outsiders, Perhaps it was naivety, perhaps to cope with extreme weather, perhaps it was their inability but the British never really got to grips with the monsoon. For thousands of years, 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. When the rains came, the water was filtered through the surrounding ground like a gigantic bucket. and held in the well as they were known, But these stepwells, were more than water collectors. it turned the mundane need for water The genius of this design was into a social ritual. to dip for water - they gossiped, People didn't just come here they bathed, they even worshipped. up until the 19th century. Over 3,000 stepwells were built, they were the main source of water. For millions,

like this helped the Indian people Despite the fact that structures the British didn't like it. survive droughts, they drank from was bad news. bathing in the same water They were concerned that people they shut them down. So on health grounds, I mean, they may have had a point, by bringing in piped water, and they solved that issue they imported another problem but at the same time,

that was much, much worse. It's a little-known fact, on a colossal scale across India, but the British built canals of them - more than 57,000 kilometres engineering achievement anywhere. perhaps their biggest even more than stepwells, Yet the British didn't realise that, these huge bodies of standing water were a health hazard - the perfect environment for malaria to breed and spread. Given the lack of sensitivity the British showed to the Indian climate, it's perhaps ironic that the monsoon played a significant role in undermining British rule in India. At the end of the 19th century, the monsoon rains failed. For a decade, there were repeated droughts. Crops were ruined, and there were terrible famines. But the British failed to respond effectively - in fact, they even continued to export rice. This indifference to the rhythms of the monsoon fuelled popular anger against colonial rule, and the independence movement grew rapidly. Today, the stepwells 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 were the Khmers, and from the 9th century, they dominated the area we now know as Cambodia. And this was their greatest achievement... the legendary temple complex of Angkor. You get a real sense of the age of this place here, cos this was built over 1,200 years ago. In a few places, like here, you can see it's showing the age. Look, the faces have all gone, but, look at this, that looks as if it could have been carved just yesterday. (THUNDER CRASHES) Angkor was built to honour the Hindu gods and it symbolised the extraordinary success of the Khmers. In a way, 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. Today, it's home to a floating, permanent community, replete with all the necessary amenities. All life here is lived on the river - the whole village, houses, shops, churches, schools, everything. A hardware store! Everybody's watching telly. They're all watching soap operas, or just chilling out. People settle here today for the same reason the Khmers did over 1,000 years ago - the unusual behaviour of the lake around monsoon time. Each year when the monsoon rains fall, the land around here just can't drain fast enough, and this lake, Tonle Sap, swells enormously. It more than trebles in size, becoming, for just a few months, the largest freshwater lake in Southeast Asia. And every year, the water brings with it a spectacular bounty. Fish! Loads of them, nibbling away at your toes in this murky water. So many, that when it floods, the Tonle Sap lake becomes the richest source of freshwater fish in the world. Back in the 9th century, the Khmers realised that this annual influx of fish and water offered a glittering opportunity. They set about building a fishing industry here, and with the profits, they built the temples of Angkor. But as it grew, the Khmer kingdom faced a stumbling block. When the monsoon finished each year, the fish and water would vanish. So each year, the inhabitants were plunged into drought and hunger. The Khmer rose to the challenge magnificently. They decided that rather than be at the whim of the monsoon, they would make it work for them. This is part of a vast network of irrigation tunnels that crisscross the whole of Angkor. When the Khmer started digging these in the 9th century, people had seen nothing like them. This was plumbing on a grand scale. From the air, it's still visible today. Over 1,000 years ago, the Khmers managed to divert a river by 80 kilometres. They built canals that extended over an area of 1,000 square kilometres and dug reservoirs that could hold up to 600 million cubic metres of monsoon water. With this system, the Khmers seized control of the planet's water cycle. They turned the seasonal rainfall of the monsoon into a reliable, all-year-round water supply. It was an enormous achievement, enabling Angkor at its peak to support a population in excess of one million. Thanks to their control of water, the Khmers had built the largest pre-industrial city in the world. The Khmer hung on until the 15th century, which was when the kingdom of Angkor finally went to the wall. They were victims of their own success. Their population went through the roof, and they simply outstripped their resources, including - despite all that incredible engineering - including the water supply. I guess that there are limits to what even the mighty monsoon can sustain. Today, we control water on a massive scale. The world's reservoirs now hold over 10,000 cubic kilometres of water. That's five times as much water as in all the rivers on Earth. And because most of it is pooled in the more populated northern hemisphere, away from the equator, the extra weight has slightly changed how the Earth spins on its axis. It's caused the Earth's rotation to speed up, shortening the day by 8 millionths of a second in the last 40 years. Today, 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. In many parts of the world, scarcity has led to a bitter struggle for control over the available supply. And that's true in even the wealthiest countries. Today, Los Angeles is a city with every luxury and convenience. Yet not so long ago, at the turn of the last century, Los Angeles was struggling. LA's problem was its location, 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. 400 kilometres to the north of the growing city, nestled within the Sierra Nevada mountain range, was a place called Owens Valley. It was a verdant place, 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. It wasn't long before men appeared in the valley, masquerading as investors. They offered to buy up farmland at seemingly irresistible prices, just to get the water rights that went with it. It wasn't technically illegal, but it was certainly shady. And it worked. In 1913, after six years of construction, an aqueduct was opened. And this is it. In a way, this aqueduct was a triumph, 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. A kind of loose resistance movement started, and they would take over places like this and open the sluice gates, allowing the water to pour back down into Owens Valley. And regularly they'd dynamite the aqueduct. But the city rebuilt it, and a game of cat and mouse continued for three more dynamite-filled years. Eventually, the police clamped down with a "shoot to kill" policy, and the rebellion fizzled out. The city had won. Today, the Los Angeles Aqueduct is just part of a giant network of pipes and aqueducts all serving one of the world's great cities. But, back in Owens Valley, the lake has all but vanished, and the river is barely a trickle. The story of Owens Valley is not an isolated case. Today, there are conflicts over water taking place all around the world. Israel, the Palestinians, Syria and Jordan dispute access to the River Jordan. Egypt, Sudan and Ethiopia quarrel over the waters of the Nile. On the Indus river, 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. 10,000 years ago, we lived at the whim of the unpredictable water cycle. Since then, 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. Today, 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. It's the one resource, more than any other, 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. Now, that prospect may find you gloomy or, like me, more optimistic. But either way, at least the future's in our hands. Next time, wind. For thousands of years, the wind has shaped the destiny of people across the planet. It's made fortunes and brought ruin.

Even today, we're still at its mercy.

This Program is Captioned

Good evening, Ali Moore with

Good evening, Ali Moore with a Lateline update. The Japanese Government has conceded that

radiation levels near a

quake-stricken nuclear power plant

are harmful. The dire warning came today after

today after another two explosions