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[radio static]

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[radio beeps]

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[indistinct chatter over radio]

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[narrator] <i>Just 50 years ago,</i>

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00:00:23,483 --> 00:00:26,319
<i>we finally ventured to the moon.</i>

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<i>For the very first time,</i>

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<i>we looked back at our own planet.</i>

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<i>Since then, the human population</i>
<i>has more than doubled.</i>

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<i>This series will celebrate</i>
<i>the natural wonders that remain</i>

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<i>and reveal what we must preserve</i>

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<i>to ensure people and nature thrive.</i>

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<i>Fresh water.</i>

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<i>Everything that lives on land,</i>
<i>animal or plant,</i>

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<i>depends upon it.</i>

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<i>Yet only one percent of it</i>
<i>is within reach.</i>

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<i>The desert of central Australia.</i>

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<i>One of the hottest, driest places</i>
<i>on Earth.</i>

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<i>Virtually nothing can live here</i>
<i>for any length of time.</i>

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<i>Yet once a decade,</i>
<i>this vast, empty desert is transformed.</i>

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<i>For that to happen,</i>
<i>a chain reaction has to be triggered</i>

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<i>two thousand kilometers to the north.</i>

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<i>There, each year,</i>
<i>the moisture-laden clouds of the monsoon</i>

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<i>begin to build.</i>
[thunder rumbling]

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<i>Eventually they burst,</i>
<i>and the process begins.</i>

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<i>Riverbeds that have been dry for years</i>
<i>suddenly fill.</i>

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[birdsong]

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<i>The torrents join together</i>
<i>and race towards the interior</i>

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<i>and the lowest land on the continent.</i>

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<i>Here, they flood over the desert</i>
<i>and create Australia's largest lake,</i>

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<i>Kati Thanda, Lake Eyre.</i>

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<i>Huge numbers of fish</i>
<i>swim down these wide waterways</i>

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<i>and into the growing lake.</i>

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<i>Pelicans arrive from Australia's coasts,</i>
<i>hundreds of kilometers away.</i>

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<i>Many will only see the lake fill</i>
<i>once in their entire lives,</i>

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<i>so how they know the lake has formed,</i>
<i>and in which direction to reach it,</i>

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<i>is still a mystery.</i>

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[pelicans cawing]

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<i>These new waters now contain so much food</i>
<i>that the birds start to breed.</i>

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<i>But the clock is ticking.</i>

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<i>The pelicans feed...</i>

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<i>and feed...</i>

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<i>and feed.</i>

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<i>The chicks must grow quickly,</i>

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<i>for they have to be strong enough</i>
<i>to leave within a matter of weeks.</i>

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<i>But time is short,</i>

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<i>for the parents</i>
<i>will only be able to find food</i>

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<i>while the water remains.</i>

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<i>The young pelicans set off</i>
<i>on their first long journey.</i>

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<i>It will be a demanding one, to the coast,</i>

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<i>and the nearest is 500 kilometers away.</i>

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<i>The lake will soon dry,</i>

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<i>and water may not return here</i>
<i>for another decade.</i>

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<i>This boom to bust transformation</i>
<i>is an exceptional event.</i>

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<i>But everywhere,</i>
<i>the availability of fresh water</i>

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<i>is becoming increasingly unpredictable</i>
<i>and uncertain.</i>

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<i>Much of the planet's fresh water,</i>
<i>however, is locked away.</i>

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<i>Almost two-thirds of it</i>
<i>lies frozen around the poles.</i>

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<i>This ice is several kilometers thick</i>

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<i>and may have been lying here</i>
<i>for millions of years.</i>

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<i>Every summer, some of it melts</i>

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<i>and carves its way</i>
<i>into the heart of the glaciers.</i>

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<i>These great caves</i>
<i>are beautiful and romantic,</i>

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<i>but they're also dangerous places,</i>
<i>for glaciers are always on the move.</i>

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[glacier creaking]
<i>Even away from the poles,</i>

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<i>much of the land's fresh water</i>
<i>freezes each winter.</i>

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<i>But when spring arrives,</i>
<i>this vast snowy reservoir melts</i>

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<i>and a great journey begins.</i>

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<i>Racing down the steep mountain slopes,</i>

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<i>the ice-cold waters</i>
<i>collect a life-giving ingredient...</i>

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<i>oxygen.</i>

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<i>Here, on the rivers of the Andes</i>
<i>in South America,</i>

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<i>there is a living to be made</i>

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<i>for those that can cope</i>
<i>with the powerful currents.</i>

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<i>And torrent ducks can.</i>

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[ducks squawking]

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<i>These chilly headwaters</i>
<i>may be oxygen-rich,</i>

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<i>but they contain few nutrients.</i>

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<i>The torrent ducks collect</i>
<i>what little food there is</i>

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<i>from below the surface.</i>

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<i>Stonefly and mayfly larvae have gills,</i>

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<i>with which they extract oxygen</i>
<i>from the water.</i>

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<i>Their flattened bodies</i>
<i>resist the relentless pull of the current.</i>

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<i>Black fly larvae.</i>

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<i>One of the ducks' favorite prey.</i>

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<i>Their specialized mouthparts</i>
<i>filter out the tiny particles of food</i>

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<i>as they race by.</i>

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<i>Hooks at the rear end</i>
<i>anchor them to the rocks,</i>

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<i>but the current</i>
<i>is sometimes irresistible.</i>

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<i>However, they have a special safety line,</i>
<i>with which they can pull themselves back.</i>

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<i>Every year, visitors come</i>
<i>to these rushing, oxygen-rich waters.</i>

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<i>Salmon.</i>

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<i>They have spent most of their lives</i>
<i>in the Pacific Ocean.</i>

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<i>Now, fully grown, they're returning</i>
<i>to the particular rivers in North America</i>

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<i>where they will now lay their eggs.</i>

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<i>Salmon have an extraordinary ability</i>
<i>to leap up waterfalls,</i>

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<i>but even they cannot, unaided,</i>
<i>cross the dams that we have built.</i>

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<i>Today, Pacific salmon number less than</i>
<i>one percent of the numbers they used to,</i>

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<i>and that's causing problems</i>
<i>for many other animals.</i>

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<i>Alaskan brown bears</i>
<i>wait for them at the waterfalls.</i>

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<i>Without these fish,</i>

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<i>the bears cannot build up</i>
<i>the fat reserves they need</i>

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<i>to sustain themselves</i>
<i>through their long winter hibernation.</i>

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<i>There is fierce competition</i>
<i>for the best fishing spots.</i>

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[growling]
[gulls cawing]

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<i>Where water flows over hard rock,</i>
<i>it collects few nutrients,</i>

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<i>so few plants can grow in it.</i>

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<i>Here, in South America, however,</i>

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<i>this plant, Macarenia,</i>
<i>manages to flourish.</i>

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<i>For a few months each year,</i>

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<i>when the water level is low enough</i>
<i>for sunlight to reach the bottom,</i>

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<i>the Macarenia bursts into bloom.</i>

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<i>This is the Caño Cristales,</i>
<i>Colombia's rainbow river.</i>

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<i>Sometimes, however,</i>
<i>water disappears underground,</i>

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<i>beyond the reach of light,</i>

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<i>and there, no plants can live.</i>

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<i>Thirty percent of the planet's fresh water</i>
<i>lies beneath the surface of the land,</i>

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<i>either within the substance</i>
<i>of porous rocks</i>

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<i>or as subterranean lakes and rivers.</i>

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<i>Made slightly acid by rain,</i>

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<i>it slowly dissolves limestone,</i>
<i>creating great caves.</i>

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<i>A labyrinth of such passages and chambers</i>
<i>underlies much of the state of Florida.</i>

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<i>For the most part, they're barren.</i>

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00:14:29,661 --> 00:14:33,415
<i>But where the water comes to the surface,</i>
<i>it's full of life.</i>

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<i>Fish are abundant.</i>

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<i>And so are fish eaters.</i>

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<i>Otters.</i>

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<i>All over the state,</i>
<i>fresh water bubbles to the surface</i>

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<i>from the greatest concentration of springs</i>
<i>on Earth.</i>

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<i>They feed rivers and pools,</i>
<i>in which all kinds of life flourish,</i>

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<i>including one of Florida's specialities...</i>

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<i>manatees.</i>

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<i>Many spend the summer in the sea,</i>

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<i>but when winter approaches,</i>
<i>they swim up the rivers,</i>

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<i>which are relatively warm.</i>

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<i>And there they graze</i>
<i>on an abundance of freshwater plants.</i>

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<i>But human beings are now taking</i>
<i>so much water from these springs,</i>

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<i>and polluting many of the others,</i>

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<i>that the manatees</i>
<i>are losing their winter homes.</i>

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<i>Rivers, being comparatively shallow,</i>
<i>warm quickly,</i>

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<i>and in spring, across Europe,</i>

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<i>the rising temperatures</i>
<i>trigger a sudden surge of life.</i>

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[tweets]

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<i>On Hungary's Tisza River,</i>
<i>giant mayfly are starting to emerge.</i>

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<i>For three years,</i>
<i>they've lived underwater as larvae.</i>

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<i>Now, in just three hours,</i>

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<i>millions of the winged adults</i>
<i>dance together and mate before they die.</i>

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<i>This extraordinary spectacle</i>
<i>was once common in Eastern Europe,</i>

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00:17:45,774 --> 00:17:49,069
<i>but so many rivers</i>
<i>now have stabilized banks</i>

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00:17:49,152 --> 00:17:50,862
<i>and are badly polluted</i>

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00:17:50,946 --> 00:17:53,323
<i>that the mayflies</i>
<i>have largely disappeared.</i>

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00:17:56,701 --> 00:18:00,997
<i>But when the rivers are clean,</i>
<i>wildlife is quick to return.</i>

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00:18:23,395 --> 00:18:27,149
<i>The kingfisher,</i>
<i>the most glorious of divers.</i>

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00:18:57,095 --> 00:19:00,891
<i>The osprey, the most skillful of graspers.</i>

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00:19:39,346 --> 00:19:43,975
<i>Iguazu, on the frontier</i>
<i>between Brazil and Argentina.</i>

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00:19:46,519 --> 00:19:50,023
<i>These are</i>
<i>the largest waterfalls on the planet.</i>

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00:19:51,733 --> 00:19:56,655
<i>Thousands of tons of fresh water</i>
<i>thunder over them every second.</i>

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00:20:06,998 --> 00:20:11,461
<i>Much of Iguazu's water</i>
<i>comes from the Amazon rainforest,</i>

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00:20:11,544 --> 00:20:13,421
<i>a thousand kilometers away.</i>

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00:20:22,722 --> 00:20:26,726
<i>There, it rose as vapor</i>
<i>from the surface of the jungle canopy.</i>

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00:20:28,561 --> 00:20:32,357
<i>A single tree can give off</i>
<i>a thousand liters a day.</i>

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00:20:34,276 --> 00:20:39,781
<i>As the vapor rises into the sky,</i>
<i>it condenses into clouds.</i>

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00:20:43,076 --> 00:20:46,955
<i>Twenty billion tons of water</i>
<i>leave the forest each day,</i>

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00:20:47,038 --> 00:20:50,125
<i>more than travels</i>
<i>down the Amazon River itself.</i>

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00:20:53,336 --> 00:20:55,672
<i>If the rainforest is destroyed,</i>

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00:20:55,755 --> 00:20:58,300
<i>this life-giving cycle will be broken.</i>

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00:21:00,343 --> 00:21:04,306
<i>As the clouds travel across the continent,</i>
<i>they shed their water,</i>

167
00:21:04,389 --> 00:21:07,058
<i>irrigating farmland and forest alike.</i>

168
00:21:08,310 --> 00:21:10,145
<i>And on the plains of Brazil,</i>

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00:21:10,228 --> 00:21:13,940
<i>they create</i>
<i>the largest tropical wetland on Earth,</i>

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00:21:14,899 --> 00:21:16,109
<i>the Pantanal.</i>

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00:21:17,986 --> 00:21:22,365
<i>Each year, however,</i>
<i>seasonal changes reduce the river's flow,</i>

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00:21:22,449 --> 00:21:26,202
<i>and the Pantanal shrinks</i>
<i>to just a few river channels.</i>

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00:21:31,416 --> 00:21:34,336
<i>This suits the top predator very well.</i>

174
00:21:38,298 --> 00:21:39,257
<i>The jaguar.</i>

175
00:21:42,177 --> 00:21:44,554
<i>It's a competent swimmer, but in water,</i>

176
00:21:44,637 --> 00:21:48,516
<i>it can't make the killing pounce</i>
<i>which makes it such a fearsome hunter.</i>

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00:21:49,017 --> 00:21:50,310
[mewls]

178
00:21:53,938 --> 00:21:55,732
<i>Now, in the dry season,</i>

179
00:21:57,484 --> 00:21:59,778
<i>the banks can get somewhat crowded.</i>

180
00:22:04,783 --> 00:22:09,245
<i>But the jaguar has spotted prey</i>
<i>on the river's edge.</i>

181
00:22:24,260 --> 00:22:25,095
<i>Capybara.</i>

182
00:22:28,598 --> 00:22:30,975
<i>It must get close to be successful.</i>

183
00:22:59,879 --> 00:23:04,217
<i>Two capybara incautiously</i>
<i>are standing in the shallows.</i>

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00:23:15,895 --> 00:23:17,313
<i>They have seen one another.</i>

185
00:23:22,986 --> 00:23:24,362
<i>Which will run first?</i>

186
00:23:25,196 --> 00:23:26,156
[barks]

187
00:23:47,260 --> 00:23:52,098
<i>Farther along the river,</i>
<i>dense vegetation provides better cover,</i>

188
00:23:54,225 --> 00:23:56,769
<i>but the bank here is quite high.</i>

189
00:24:00,482 --> 00:24:02,942
<i>Capybara have acute hearing.</i>

190
00:24:05,904 --> 00:24:07,989
<i>-One noisy footfall...</i>
-[branch snaps]

191
00:24:09,282 --> 00:24:10,533
<i>...and the chance is lost.</i>
<i>Another failure.</i>

192
00:24:57,288 --> 00:24:58,164
[barks]

193
00:25:10,552 --> 00:25:14,639
<i>Perhaps it's time to try a different prey.</i>

194
00:25:21,479 --> 00:25:23,606
<i>Tackling one of these would be risky,</i>

195
00:25:24,190 --> 00:25:26,818
<i>but the jaguar is really hungry.</i>

196
00:25:36,869 --> 00:25:38,913
<i>If a jaguar is to catch a caiman,</i>

197
00:25:38,997 --> 00:25:43,668
<i>it must bite its neck and then hold on</i>
<i>to prevent the caiman striking back.</i>

198
00:25:46,504 --> 00:25:50,550
<i>It has to get into a position</i>
<i>directly above its prey.</i>

199
00:25:56,848 --> 00:25:58,600
<i>This is dangerous.</i>

200
00:26:21,456 --> 00:26:24,626
<i>The caiman rolls</i>
<i>to try and drown the jaguar.</i>

201
00:26:30,423 --> 00:26:32,675
<i>Predator and prey seem evenly matched.</i>

202
00:26:40,016 --> 00:26:41,976
<i>The jaguar won't let go.</i>

203
00:27:01,162 --> 00:27:06,793
<i>After 20 minutes, and near to exhaustion,</i>
<i>the jaguar wins.</i>

204
00:27:17,136 --> 00:27:21,557
<i>Sometimes, a river's downward journey</i>
<i>is interrupted by lakes.</i>

205
00:27:22,850 --> 00:27:28,773
<i>Together, they contain 40 times more water</i>
<i>than all the world's rivers combined.</i>

206
00:27:31,984 --> 00:27:34,278
<i>Africa's Lake Tanganyika</i>

207
00:27:34,362 --> 00:27:39,200
<i>holds almost a fifth</i>
<i>of all accessible fresh water on Earth.</i>

208
00:27:44,288 --> 00:27:49,419
<i>But, considering its great size,</i>
<i>Tanganyika contains little life.</i>

209
00:27:55,591 --> 00:27:58,428
<i>It's almost a kilometer and a half deep,</i>

210
00:27:59,137 --> 00:28:03,766
<i>but at the bottom the water barely moves</i>
<i>and there is no oxygen.</i>

211
00:28:06,269 --> 00:28:11,107
<i>It's only close to the surface,</i>
<i>in its top 150 meters,</i>

212
00:28:11,190 --> 00:28:15,027
<i>that the water contains enough oxygen</i>
<i>for life to exist.</i>

213
00:28:17,864 --> 00:28:21,033
<i>But here, it flourishes in abundance.</i>

214
00:28:24,120 --> 00:28:28,332
<i>Two hundred and fifty species</i>
<i>of cichlid fish have evolved here,</i>

215
00:28:28,416 --> 00:28:30,585
<i>many of which are found nowhere else.</i>

216
00:28:40,803 --> 00:28:44,640
<i>Competition in these crowded waters</i>
<i>is intense.</i>

217
00:28:47,852 --> 00:28:51,773
<i>A male callipterus cichlid</i>
<i>collects shells.</i>

218
00:28:53,983 --> 00:28:58,321
<i>The more shells a male has,</i>
<i>the more females he will attract.</i>

219
00:29:03,034 --> 00:29:05,119
<i>And this one is doing very well.</i>

220
00:29:34,690 --> 00:29:37,819
<i>His neighbor has a rather smaller mound.</i>

221
00:29:43,783 --> 00:29:46,035
<i>And the neighbor is a thief.</i>

222
00:29:52,166 --> 00:29:53,876
<i>As soon as he turns his back,</i>

223
00:29:57,129 --> 00:29:59,090
<i>the thief swoops in...</i>

224
00:30:01,843 --> 00:30:03,427
<i>and steals a shell.</i>

225
00:30:14,230 --> 00:30:18,693
<i>The hardworking owner of the larger mound</i>
<i>doesn't seem to notice.</i>

226
00:30:21,445 --> 00:30:25,116
<i>So, the thief commits the crime again...</i>

227
00:30:27,034 --> 00:30:27,869
<i>and again...</i>

228
00:30:32,248 --> 00:30:35,710
<i>until he has built the largest mound.</i>

229
00:30:40,214 --> 00:30:42,758
<i>The shells are not just for display.</i>

230
00:30:42,842 --> 00:30:46,512
<i>They will be used by the females</i>
<i>as cradles.</i>

231
00:30:50,349 --> 00:30:51,809
<i>One arrives.</i>

232
00:30:52,435 --> 00:30:55,646
<i>She's tiny, only a tenth of his size.</i>

233
00:30:57,732 --> 00:31:01,319
<i>She's so small,</i>
<i>she can slip inside a shell.</i>

234
00:31:10,286 --> 00:31:15,374
<i>There, she lays her eggs,</i>
<i>and the male quickly fertilizes them.</i>

235
00:31:18,169 --> 00:31:23,466
<i>She will then stay inside protecting them</i>
<i>for up to a fortnight until they hatch.</i>

236
00:31:29,388 --> 00:31:30,389
<i>The emperor,</i>

237
00:31:30,473 --> 00:31:33,100
<i>the largest of all the cichlids</i>
<i>in Tanganyika.</i>

238
00:31:36,020 --> 00:31:40,441
<i>At almost a meter long, this female</i>
<i>must raise her young in the open.</i>
<i>Guarding them is therefore</i>
<i>a full-time job for both parents.</i>

239
00:32:00,169 --> 00:32:03,673
<i>But the future for all these fish</i>
<i>is uncertain.</i>

240
00:32:07,134 --> 00:32:11,430
<i>As global temperatures rise,</i>
<i>Lake Tanganyika is warming.</i>

241
00:32:13,474 --> 00:32:16,769
<i>Its waters are no longer mixing as well</i>
<i>as they once did,</i>

242
00:32:17,269 --> 00:32:20,606
<i>so the top oxygenated layer is reducing.</i>

243
00:32:31,117 --> 00:32:33,536
<i>The Mekong River in Southeast Asia.</i>

244
00:32:34,412 --> 00:32:39,250
<i>Four thousand kilometers long</i>
<i>and with the widest falls anywhere.</i>

245
00:32:43,170 --> 00:32:47,925
<i>Today, over 60 million people</i>
<i>depend upon it for their livelihood.</i>

246
00:33:11,157 --> 00:33:15,119
<i>The monsoon rains create</i>
<i>such a colossal surge of water</i>

247
00:33:15,202 --> 00:33:17,830
<i>that the falls themselves</i>
<i>almost disappear.</i>

248
00:33:20,875 --> 00:33:23,127
<i>The water is loaded with sediment,</i>

249
00:33:23,210 --> 00:33:27,214
<i>collected during the Mekong's long journey</i>
<i>from the Tibetan Plateau.</i>

250
00:33:30,551 --> 00:33:35,264
<i>Even before the flood,</i>
<i>the water covers a vast area of land.</i>

251
00:33:41,395 --> 00:33:44,273
<i>These exposed roots are evidence</i>

252
00:33:44,356 --> 00:33:47,318
<i>of the great rise in water level</i>
<i>that is to come.</i>

253
00:33:52,823 --> 00:33:54,617
<i>When the main flood does arrive,</i>

254
00:33:54,700 --> 00:33:57,703
<i>the trees are submerged</i>
<i>up to their branches.</i>

255
00:34:02,583 --> 00:34:07,338
<i>For a few months, the floodwaters create</i>
<i>the planet's greatest breeding grounds</i>

256
00:34:07,421 --> 00:34:08,756
<i>for freshwater fish.</i>

257
00:34:12,718 --> 00:34:16,764
<i>One species</i>
<i>has a particularly ingenious solution</i>

258
00:34:16,847 --> 00:34:20,684
<i>to the problems of living</i>
<i>in shallow, oxygen-poor water.</i>

259
00:34:23,979 --> 00:34:26,190
<i>The Siamese fighting fish.</i>

260
00:34:31,654 --> 00:34:35,116
<i>The male breathes</i>
<i>by gulping air from the surface,</i>

261
00:34:35,199 --> 00:34:36,742
<i>and during the breeding season</i>

262
00:34:36,826 --> 00:34:40,746
<i>he uses that ability</i>
<i>to build a raft of bubbles.</i>

263
00:34:42,623 --> 00:34:45,209
<i>Day after day he labors.</i>

264
00:34:52,091 --> 00:34:56,929
<i>A female, waiting nearby,</i>
<i>rises to inspect the raft.</i>

265
00:35:11,902 --> 00:35:16,949
<i>They wrap themselves around one another</i>
<i>in a tender embrace.</i>

266
00:35:26,917 --> 00:35:30,671
<i>This union encourages her</i>
<i>to release her eggs.</i>

267
00:35:33,674 --> 00:35:37,136
<i>As they sink downwards,</i>
<i>the male fertilizes them.</i>

268
00:35:42,975 --> 00:35:44,977
<i>Both carefully collect them,</i>

269
00:35:49,773 --> 00:35:54,945
<i>and then blow them, one by one,</i>
<i>into the bubble nest.</i>

270
00:35:58,908 --> 00:36:01,911
<i>Oxygen is scarce in these stagnant waters,</i>

271
00:36:01,994 --> 00:36:04,371
<i>but the eggs</i>
<i>will get enough from the bubbles</i>

272
00:36:04,455 --> 00:36:05,831
<i>to allow them to develop.</i>

273
00:36:08,500 --> 00:36:11,378
<i>The climax of the flood is still to come.</i>

274
00:36:14,048 --> 00:36:17,718
<i>Eventually,</i>
<i>so much water surges down the Mekong</i>

275
00:36:17,801 --> 00:36:23,432
<i>that the Tonlé Sap Lake expands</i>
<i>to five times its dry-season size.</i>

276
00:36:25,809 --> 00:36:30,481
<i>Vast numbers of fish now swim</i>
<i>into these new feeding grounds.</i>

277
00:36:32,483 --> 00:36:36,320
<i>People have harvested this seasonal event</i>
<i>for millennia.</i>

278
00:36:37,863 --> 00:36:40,157
<i>They set nets across half of the river,</i>

279
00:36:40,658 --> 00:36:42,576
<i>leaving the other half free</i>

280
00:36:42,660 --> 00:36:45,496
<i>for the rest of the fish</i>
<i>to swim on and breed.</i>

281
00:36:49,583 --> 00:36:55,214
<i>The Mekong, in fact, supports</i>
<i>the largest inland fishery in the world.</i>

282
00:37:01,595 --> 00:37:06,058
<i>One-fifth of all the freshwater fish</i>
<i>caught by people worldwide</i>

283
00:37:06,558 --> 00:37:08,686
<i>comes from this one river system.</i>

284
00:37:11,063 --> 00:37:13,107
<i>But the future of the Mekong,</i>

285
00:37:13,190 --> 00:37:15,693
<i>like that of so many other rivers</i>
<i>around the world,</i>

286
00:37:15,776 --> 00:37:17,736
<i>is increasingly at risk.</i>

287
00:37:21,156 --> 00:37:23,200
<i>We have changed the natural flow</i>

288
00:37:23,284 --> 00:37:26,829
<i>of more than two-thirds</i>
<i>of the planet's longest rivers</i>

289
00:37:26,912 --> 00:37:31,041
<i>by, amongst other things,</i>
<i>building dams across them.</i>

290
00:37:39,550 --> 00:37:44,179
<i>So now, many rivers across the world</i>
<i>no longer flow.</i>

291
00:37:51,020 --> 00:37:54,940
<i>Here in East Africa, in Ruaha, Tanzania,</i>

292
00:37:55,899 --> 00:37:58,360
<i>these elephants are searching for water.</i>

293
00:38:01,822 --> 00:38:08,120
<i>Each needs to drink 200 liters every day,</i>
<i>and there doesn't seem to be any here.</i>

294
00:38:09,747 --> 00:38:14,752
<i>But the elephants know that baobab wood</i>
<i>contains a lot of moisture.</i>

295
00:38:17,254 --> 00:38:21,258
<i>And in an emergency,</i>
<i>they eat it in great quantities.</i>

296
00:38:28,557 --> 00:38:31,143
<i>Lions also need water.</i>

297
00:38:35,814 --> 00:38:41,070
<i>And conveniently for the lions,</i>
<i>water is where their prey will gather.</i>

298
00:38:44,948 --> 00:38:48,911
<i>So both predators and prey</i>
<i>head for the rivers.</i>

299
00:38:54,875 --> 00:38:56,377
<i>Until 30 years ago,</i>

300
00:38:56,460 --> 00:38:59,380
<i>rivers in this part of Africa</i>
<i>never ran dry.</i>

301
00:39:04,760 --> 00:39:08,680
<i>Now, agriculture upstream</i>
<i>is taking great quantities,</i>

302
00:39:08,764 --> 00:39:13,394
<i>and during the dry season,</i>
<i>the rivers shrink into isolated pools.</i>

303
00:39:30,536 --> 00:39:36,250
<i>Hippos rely on flowing water</i>
<i>to keep themselves cool during the day,</i>

304
00:39:36,875 --> 00:39:40,254
<i>but now they have to make do with mud.</i>

305
00:39:44,508 --> 00:39:48,470
<i>As the water level falls still further,</i>
<i>they cram together.</i>

306
00:39:52,683 --> 00:39:54,518
<i>Tempers begin to fray.</i>

307
00:40:03,944 --> 00:40:05,612
[roaring]

308
00:40:14,830 --> 00:40:20,752
<i>Each day, the mud pools shrink further,</i>
<i>and the hippos' plight worsens.</i>

309
00:40:33,849 --> 00:40:37,019
<i>Buffalo, in the urgent search for water.</i>

310
00:40:49,114 --> 00:40:52,993
<i>The lions are already here</i>
<i>at this water hole.</i>

311
00:41:01,877 --> 00:41:07,174
<i>However, the buffalo are driven on</i>
<i>by their desperate need for fresh water.</i>

312
00:41:20,979 --> 00:41:23,357
<i>They need to drink every day.</i>

313
00:41:38,830 --> 00:41:41,124
<i>Every drink is now a risk,</i>

314
00:41:42,876 --> 00:41:44,836
<i>but the buffalo have no choice.</i>

315
00:42:59,786 --> 00:43:03,790
<i>As the drought continues,</i>
<i>the buffalo begin to weaken.</i>

316
00:43:05,667 --> 00:43:08,629
<i>The odds are changing,</i>
<i>in the lions' favor.</i>

317
00:43:24,519 --> 00:43:27,230
<i>The elephants have reached their river.</i>

318
00:43:31,068 --> 00:43:35,155
<i>Nothing else is here because it's dry.</i>

319
00:43:47,250 --> 00:43:50,921
<i>But elephants can find water</i>
<i>where others can't.</i>

320
00:43:52,714 --> 00:43:57,094
<i>They use their trunks to dig holes</i>
<i>in the sand of the riverbed.</i>

321
00:44:06,603 --> 00:44:09,314
<i>The extraordinary sense of smell</i>

322
00:44:09,398 --> 00:44:13,110
<i>that enables them to detect open water</i>
<i>from kilometers away</i>

323
00:44:13,819 --> 00:44:17,447
<i>also helps them</i>
<i>to locate places underground</i>

324
00:44:17,531 --> 00:44:20,325
<i>where it lies closest to the surface.</i>

325
00:44:25,080 --> 00:44:29,334
<i>In severe droughts,</i>
<i>the wells they dig can be their lifeline.</i>

326
00:44:38,635 --> 00:44:42,514
<i>The hardships of the dry season</i>
<i>have always been part of life</i>

327
00:44:42,597 --> 00:44:44,349
<i>on East Africa's plains,</i>

328
00:44:45,225 --> 00:44:46,893
<i>but as the planet warms,</i>

329
00:44:46,977 --> 00:44:50,647
<i>and we ourselves take so much water</i>
<i>for our own purposes,</i>

330
00:44:51,231 --> 00:44:54,735
<i>the droughts are becoming more frequent</i>
<i>and more severe.</i>

331
00:45:09,040 --> 00:45:12,919
<i>The Platte River,</i>
<i>in Nebraska, North America.</i>

332
00:45:30,937 --> 00:45:36,401
<i>Each year, sandhill cranes arrive here</i>
<i>as they travel north across America</i>

333
00:45:36,485 --> 00:45:40,489
<i>on one of the last great migrations</i>
<i>made by any animal.</i>

334
00:45:42,824 --> 00:45:45,368
<i>It's one of their crucial staging posts.</i>

335
00:45:54,002 --> 00:45:58,590
<i>The river once flooded the prairie</i>
<i>for a mile in all directions.</i>

336
00:46:02,177 --> 00:46:06,723
<i>This was a perfect place</i>
<i>for them to feed and rest.</i>

337
00:46:12,562 --> 00:46:15,023
<i>Now, we have dammed the river</i>

338
00:46:15,482 --> 00:46:18,527
<i>and taken so much of its water</i>
<i>for our own use</i>

339
00:46:19,069 --> 00:46:22,447
<i>that there is little space left</i>
<i>for the cranes.</i>

340
00:46:36,962 --> 00:46:41,550
<i>But conservationists</i>
<i>now manage the river's flow in such a way</i>

341
00:46:42,092 --> 00:46:45,846
<i>that it still creates the sandbanks</i>
<i>the cranes need.</i>

342
00:46:58,024 --> 00:47:01,027
<i>We are not alone in our need for water,</i>

343
00:47:06,992 --> 00:47:12,873
<i>but we have the ability to ensure</i>
<i>the fresh waters of the world do flow,</i>

344
00:47:14,958 --> 00:47:19,421
<i>and we alone can determine</i>
<i>how they are shared.</i>

345
00:47:29,931 --> 00:47:34,436
<i>Please visit ourplanet.com</i>
<i>to discover what we need to do now</i>

346
00:47:34,519 --> 00:47:36,771
<i>to ensure fresh water keeps flowing.</i>

347
00:47:39,274 --> 00:47:45,196
<i>♪ I can hear the whole world</i>
<i>Singing together ♪</i>

348
00:47:47,824 --> 00:47:53,747
<i>♪ I can hear the whole world</i>
<i>Say it's now or never ♪</i>

349
00:47:56,625 --> 00:48:00,879
<i>♪ 'Cause it's not too late</i>
<i>If we change our ways ♪</i>

350
00:48:00,962 --> 00:48:04,466
<i>♪ And connect the dots to our problems ♪</i>

351
00:48:04,841 --> 00:48:10,931
<i>♪ I can hear the whole world</i>
<i>Say we're in this together ♪</i>