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Just 50 years ago,
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we finally ventured to the moon.
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For the very first time,
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we looked back at our own planet.
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Since then, the human population
has more than doubled.
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This series will celebrate
the natural wonders that remain
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and reveal what we must preserve
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to ensure people and nature thrive.
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Fresh water.
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Everything that lives on land,
animal or plant,
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depends upon it.
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Yet only one percent of it
is within reach.
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The desert of central Australia.
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One of the hottest, driest places
on Earth.
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Virtually nothing can live here
for any length of time.
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Yet once a decade,
this vast, empty desert is transformed.
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For that to happen,
a chain reaction has to be triggered
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two thousand kilometers to the north.
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There, each year,
the moisture-laden clouds of the monsoon
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begin to build.
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Eventually they burst,
and the process begins.
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Riverbeds that have been dry for years
suddenly fill.
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The torrents join together
and race towards the interior
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and the lowest land on the continent.
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Here, they flood over the desert
and create Australia's largest lake,
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Kati Thanda, Lake Eyre.
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Huge numbers of fish
swim down these wide waterways
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and into the growing lake.
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Pelicans arrive from Australia's coasts,
hundreds of kilometers away.
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Many will only see the lake fill
once in their entire lives,
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so how they know the lake has formed,
and in which direction to reach it,
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is still a mystery.
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These new waters now contain so much food
that the birds start to breed.
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But the clock is ticking.
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The pelicans feed...
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and feed...
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and feed.
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The chicks must grow quickly,
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for they have to be strong enough
to leave within a matter of weeks.
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But time is short,
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for the parents
will only be able to find food
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while the water remains.
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The young pelicans set off
on their first long journey.
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It will be a demanding one, to the coast,
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and the nearest is 500 kilometers away.
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The lake will soon dry,
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and water may not return here
for another decade.
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This boom to bust transformation
is an exceptional event.
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But everywhere,
the availability of fresh water
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is becoming increasingly unpredictable
and uncertain.
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Much of the planet's fresh water,
however, is locked away.
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Almost two-thirds of it
lies frozen around the poles.
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This ice is several kilometers thick
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and may have been lying here
for millions of years.
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Every summer, some of it melts
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and carves its way
into the heart of the glaciers.
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These great caves
are beautiful and romantic,
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but they're also dangerous places,
for glaciers are always on the move.
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Even away from the poles,
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much of the land's fresh water
freezes each winter.
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But when spring arrives,
this vast snowy reservoir melts
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and a great journey begins.
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Racing down the steep mountain slopes,
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the ice-cold waters
collect a life-giving ingredient...
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oxygen.
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Here, on the rivers of the Andes
in South America,
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there is a living to be made
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for those that can cope
with the powerful currents.
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And torrent ducks can.
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These chilly headwaters
may be oxygen-rich,
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but they contain few nutrients.
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The torrent ducks collect
what little food there is
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from below the surface.
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Stonefly and mayfly larvae have gills,
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with which they extract oxygen
from the water.
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Their flattened bodies
resist the relentless pull of the current.
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Black fly larvae.
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One of the ducks' favorite prey.
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Their specialized mouthparts
filter out the tiny particles of food
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as they race by.
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Hooks at the rear end
anchor them to the rocks,
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but the current
is sometimes irresistible.
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However, they have a special safety line,
with which they can pull themselves back.
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Every year, visitors come
to these rushing, oxygen-rich waters.
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Salmon.
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They have spent most of their lives
in the Pacific Ocean.
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Now, fully grown, they're returning
to the particular rivers in North America
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where they will now lay their eggs.
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Salmon have an extraordinary ability
to leap up waterfalls,
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but even they cannot, unaided,
cross the dams that we have built.
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Today, Pacific salmon number less than
one percent of the numbers they used to,
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and that's causing problems
for many other animals.
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Alaskan brown bears
wait for them at the waterfalls.
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Without these fish,
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the bears cannot build up
the fat reserves they need
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to sustain themselves
through their long winter hibernation.
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There is fierce competition
for the best fishing spots.
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Where water flows over hard rock,
it collects few nutrients,
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so few plants can grow in it.
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Here, in South America, however,
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this plant, Macarenia,
manages to flourish.
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For a few months each year,
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when the water level is low enough
for sunlight to reach the bottom,
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the Macarenia bursts into bloom.
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This is the Caño Cristales,
Colombia's rainbow river.
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Sometimes, however,
water disappears underground,
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beyond the reach of light,
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and there, no plants can live.
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Thirty percent of the planet's fresh water
lies beneath the surface of the land,
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either within the substance
of porous rocks
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or as subterranean lakes and rivers.
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Made slightly acid by rain,
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it slowly dissolves limestone,
creating great caves.
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A labyrinth of such passages and chambers
underlies much of the state of Florida.
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For the most part, they're barren.
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But where the water comes to the surface,
it's full of life.
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Fish are abundant.
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And so are fish eaters.
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Otters.
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All over the state,
fresh water bubbles to the surface
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from the greatest concentration of springs
on Earth.
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They feed rivers and pools,
in which all kinds of life flourish,
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including one of Florida's specialities...
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manatees.
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Many spend the summer in the sea,
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but when winter approaches,
they swim up the rivers,
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which are relatively warm.
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And there they graze
on an abundance of freshwater plants.
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But human beings are now taking
so much water from these springs,
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and polluting many of the others,
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that the manatees
are losing their winter homes.
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Rivers, being comparatively shallow,
warm quickly,
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and in spring, across Europe,
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the rising temperatures
trigger a sudden surge of life.
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On Hungary's Tisza River,
giant mayfly are starting to emerge.
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For three years,
they've lived underwater as larvae.
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Now, in just three hours,
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millions of the winged adults
dance together and mate before they die.
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This extraordinary spectacle
was once common in Eastern Europe,
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but so many rivers
now have stabilized banks
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and are badly polluted
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that the mayflies
have largely disappeared.
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But when the rivers are clean,
wildlife is quick to return.
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The kingfisher,
the most glorious of divers.
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The osprey, the most skillful of graspers.
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Iguazu, on the frontier
between Brazil and Argentina.
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These are
the largest waterfalls on the planet.
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Thousands of tons of fresh water
thunder over them every second.
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Much of Iguazu's water
comes from the Amazon rainforest,
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a thousand kilometers away.
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There, it rose as vapor
from the surface of the jungle canopy.
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A single tree can give off
a thousand liters a day.
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As the vapor rises into the sky,
it condenses into clouds.
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Twenty billion tons of water
leave the forest each day,
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more than travels
down the Amazon River itself.
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If the rainforest is destroyed,
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this life-giving cycle will be broken.
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As the clouds travel across the continent,
they shed their water,
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irrigating farmland and forest alike.
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And on the plains of Brazil,
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they create
the largest tropical wetland on Earth,
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the Pantanal.
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Each year, however,
seasonal changes reduce the river's flow,
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and the Pantanal shrinks
to just a few river channels.
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This suits the top predator very well.
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The jaguar.
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It's a competent swimmer, but in water,
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it can't make the killing pounce
which makes it such a fearsome hunter.
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Now, in the dry season,
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the banks can get somewhat crowded.
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But the jaguar has spotted prey
on the river's edge.
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Capybara.
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It must get close to be successful.
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Two capybara incautiously
are standing in the shallows.
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They have seen one another.
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Which will run first?
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Farther along the river,
dense vegetation provides better cover,
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but the bank here is quite high.
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Capybara have acute hearing.
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One noisy footfall...
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...and the chance is lost.
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Another failure.
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Perhaps it's time to try a different prey.
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Tackling one of these would be risky,
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but the jaguar is really hungry.
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If a jaguar is to catch a caiman,
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it must bite its neck and then hold on
to prevent the caiman striking back.
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It has to get into a position
directly above its prey.
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This is dangerous.
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The caiman rolls
to try and drown the jaguar.
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Predator and prey seem evenly matched.
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The jaguar won't let go.
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After 20 minutes, and near to exhaustion,
the jaguar wins.
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Sometimes, a river's downward journey
is interrupted by lakes.
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Together, they contain 40 times more water
than all the world's rivers combined.
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Africa's Lake Tanganyika
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holds almost a fifth
of all accessible fresh water on Earth.
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But, considering its great size,
Tanganyika contains little life.
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It's almost a kilometer and a half deep,
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but at the bottom the water barely moves
and there is no oxygen.
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It's only close to the surface,
in its top 150 meters,
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that the water contains enough oxygen
for life to exist.
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But here, it flourishes in abundance.
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Two hundred and fifty species
of cichlid fish have evolved here,
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many of which are found nowhere else.
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Competition in these crowded waters
is intense.
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A male callipterus cichlid
collects shells.
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The more shells a male has,
the more females he will attract.
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And this one is doing very well.
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His neighbor has a rather smaller mound.
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And the neighbor is a thief.
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As soon as he turns his back,
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the thief swoops in...
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and steals a shell.
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00:30:14,187 --> 00:30:18,650
The hardworking owner of the larger mound
doesn't seem to notice.
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So, the thief commits the crime again...
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00:30:26,991 --> 00:30:27,991
and again...
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00:30:32,205 --> 00:30:35,667
until he has built the largest mound.
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The shells are not just for display.
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They will be used by the females
as cradles.
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One arrives.
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She's tiny, only a tenth of his size.
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She's so small,
she can slip inside a shell.
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There, she lays her eggs,
and the male quickly fertilizes them.
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She will then stay inside protecting them
for up to a fortnight until they hatch.
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The emperor,
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the largest of all the cichlids
in Tanganyika.
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At almost a meter long, this female
must raise her young in the open.
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Guarding them is therefore
a full-time job for both parents.
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But the future for all these fish
is uncertain.
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As global temperatures rise,
Lake Tanganyika is warming.
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Its waters are no longer mixing as well
as they once did,
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so the top oxygenated layer is reducing.
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The Mekong River in Southeast Asia.
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Four thousand kilometers long
and with the widest falls anywhere.
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Today, over 60 million people
depend upon it for their livelihood.
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The monsoon rains create
such a colossal surge of water
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that the falls themselves
almost disappear.
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The water is loaded with sediment,
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collected during the Mekong's long journey
from the Tibetan Plateau.
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Even before the flood,
the water covers a vast area of land.
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These exposed roots are evidence
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of the great rise in water level
that is to come.
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When the main flood does arrive,
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the trees are submerged
up to their branches.
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For a few months, the floodwaters create
the planet's greatest breeding grounds
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for freshwater fish.
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One species
has a particularly ingenious solution
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to the problems of living
in shallow, oxygen-poor water.
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The Siamese fighting fish.
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The male breathes
by gulping air from the surface,
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and during the breeding season
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he uses that ability
to build a raft of bubbles.
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Day after day he labors.
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A female, waiting nearby,
rises to inspect the raft.
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They wrap themselves around one another
in a tender embrace.
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This union encourages her
to release her eggs.
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As they sink downwards,
the male fertilizes them.
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Both carefully collect them,
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and then blow them, one by one,
into the bubble nest.
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00:35:58,865 --> 00:36:01,868
Oxygen is scarce in these stagnant waters,
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but the eggs
will get enough from the bubbles
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to allow them to develop.
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The climax of the flood is still to come.
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Eventually,
so much water surges down the Mekong
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that the Tonlé Sap Lake expands
to five times its dry-season size.
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Vast numbers of fish now swim
into these new feeding grounds.
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People have harvested this seasonal event
for millennia.
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They set nets across half of the river,
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leaving the other half free
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for the rest of the fish
to swim on and breed.
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The Mekong, in fact, supports
the largest inland fishery in the world.
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One-fifth of all the freshwater fish
caught by people worldwide
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comes from this one river system.
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But the future of the Mekong,
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like that of so many other rivers
around the world,
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is increasingly at risk.
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We have changed the natural flow
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00:37:23,241 --> 00:37:26,786
of more than two-thirds
of the planet's longest rivers
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by, amongst other things,
building dams across them.
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00:37:39,507 --> 00:37:44,136
So now, many rivers across the world
no longer flow.
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00:37:50,977 --> 00:37:54,897
Here in East Africa, in Ruaha, Tanzania,
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these elephants are searching for water.
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00:38:01,779 --> 00:38:08,077
Each needs to drink 200 liters every day,
and there doesn't seem to be any here.
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00:38:09,704 --> 00:38:14,709
But the elephants know that baobab wood
contains a lot of moisture.
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00:38:17,211 --> 00:38:21,215
And in an emergency,
they eat it in great quantities.
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00:38:28,514 --> 00:38:31,100
Lions also need water.
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00:38:35,771 --> 00:38:41,027
And conveniently for the lions,
water is where their prey will gather.
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So both predators and prey
head for the rivers.
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00:38:54,832 --> 00:38:56,334
Until 30 years ago,
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00:38:56,417 --> 00:38:59,337
rivers in this part of Africa
never ran dry.
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00:39:04,717 --> 00:39:08,637
Now, agriculture upstream
is taking great quantities,
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00:39:08,721 --> 00:39:13,351
and during the dry season,
the rivers shrink into isolated pools.
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00:39:30,493 --> 00:39:36,207
Hippos rely on flowing water
to keep themselves cool during the day,
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00:39:36,832 --> 00:39:40,211
but now they have to make do with mud.
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00:39:44,465 --> 00:39:48,427
As the water level falls still further,
they cram together.
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00:39:52,640 --> 00:39:54,475
Tempers begin to fray.
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00:40:14,787 --> 00:40:20,709
Each day, the mud pools shrink further,
and the hippos' plight worsens.
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00:40:33,806 --> 00:40:36,976
Buffalo, in the urgent search for water.
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00:40:49,071 --> 00:40:52,950
The lions are already here
at this water hole.
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00:41:01,834 --> 00:41:07,131
However, the buffalo are driven on
by their desperate need for fresh water.
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00:41:20,936 --> 00:41:23,314
They need to drink every day.
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00:41:38,787 --> 00:41:41,081
Every drink is now a risk,
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00:41:42,833 --> 00:41:44,793
but the buffalo have no choice.
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00:42:59,743 --> 00:43:03,747
As the drought continues,
the buffalo begin to weaken.
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00:43:05,624 --> 00:43:08,586
The odds are changing,
in the lions' favor.
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The elephants have reached their river.
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00:43:31,025 --> 00:43:35,112
Nothing else is here because it's dry.
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00:43:47,207 --> 00:43:50,878
But elephants can find water
where others can't.
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00:43:52,671 --> 00:43:57,051
They use their trunks to dig holes
in the sand of the riverbed.
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The extraordinary sense of smell
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that enables them to detect open water
from kilometers away
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00:44:13,776 --> 00:44:17,404
also helps them
to locate places underground
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00:44:17,488 --> 00:44:20,282
where it lies closest to the surface.
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00:44:25,037 --> 00:44:29,291
In severe droughts,
the wells they dig can be their lifeline.
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00:44:38,592 --> 00:44:42,471
The hardships of the dry season
have always been part of life
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00:44:42,554 --> 00:44:44,306
on East Africa's plains,
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00:44:45,182 --> 00:44:46,850
but as the planet warms,
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00:44:46,934 --> 00:44:50,604
and we ourselves take so much water
for our own purposes,
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00:44:51,188 --> 00:44:54,692
the droughts are becoming more frequent
and more severe.
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00:45:08,997 --> 00:45:12,876
The Platte River,
in Nebraska, North America.
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00:45:30,894 --> 00:45:36,358
Each year, sandhill cranes arrive here
as they travel north across America
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00:45:36,442 --> 00:45:40,446
on one of the last great migrations
made by any animal.
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00:45:42,781 --> 00:45:45,325
It's one of their crucial staging posts.
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00:45:53,959 --> 00:45:58,547
The river once flooded the prairie
for a mile in all directions.
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00:46:02,134 --> 00:46:06,680
This was a perfect place
for them to feed and rest.
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00:46:12,519 --> 00:46:14,980
Now, we have dammed the river
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00:46:15,439 --> 00:46:18,484
and taken so much of its water
for our own use
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00:46:19,026 --> 00:46:22,404
that there is little space left
for the cranes.
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00:46:36,919 --> 00:46:41,507
But conservationists
now manage the river's flow in such a way
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00:46:42,049 --> 00:46:45,803
that it still creates the sandbanks
the cranes need.
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00:46:57,981 --> 00:47:00,984
We are not alone in our need for water,
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00:47:06,949 --> 00:47:12,830
but we have the ability to ensure
the fresh waters of the world do flow,
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00:47:14,915 --> 00:47:19,378
and we alone can determine
how they are shared.
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00:47:29,888 --> 00:47:34,393
Please visit ourplanet.com
to discover what we need to do now
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to ensure fresh water keeps flowing.
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00:47:39,231 --> 00:47:45,153
♪ I can hear the whole world
Singing together ♪
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00:47:47,781 --> 00:47:53,704
♪ I can hear the whole world
Say it's now or never ♪
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00:47:56,582 --> 00:48:00,836
♪ 'Cause it's not too late
If we change our ways ♪
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00:48:00,919 --> 00:48:04,423
♪ And connect the dots to our problems ♪
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00:48:04,798 --> 00:48:10,888
♪ I can hear the whole world
Say we're in this together ♪
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00:48:10,971 --> 00:48:12,723
♪ We're in this together ♪