Earth: A New Wild (2015) s01e05 Episode Script
Water
The wilds of planet Earth are spectacular.
Yet one species is always missing from the picture.
Us.
I'm Dr.
M.
Sanjayan.
As a scientist and conservationist, I've dedicated the past 25 years of my life to studying and protecting the wildlife I love.
Hold on, buddy! Now, my mission is to tell you an untold story, where we humans are not separate from nature.
We are part of it.
And nowhere do we rely on nature more than in our thirst for water.
We've learned the hard way that if we disrupt the flow of water too much, both wildlife and humans can suffer.
I'm just hot, man.
I'm gonna collapse.
But on my journey, I'm discovering that by changing our perspective, we can restore the natural pulse of water.
Are you seeing this? The results can be extraordinary.
February 25h, 2015 In northern Kenya, for half the year, little or no rain will fall.
During this dry season, animals face a stark reality-- find water or die.
The trouble is, for hundreds of miles around, the rivers here run dry.
So wherever you find water like this, accessible from the surface, you will find the most amazing collection of wildlife.
This whole ecology of these areas, these dry areas, is based on water.
These elephants would not be here if not for the water.
They wouldn't be able to find enough to live out here.
Water is so vital, even natural enemies declare an uneasy truce when it comes to drinking.
But these watering holes wouldn't exist if it weren't for the actions of one particular species- us.
For centuries, people like these Samburu warriors have known a secret.
In certain spots beneath the sand, the bedrock forces the water close to the surface.
So when the rest of East Africa lies parched, here they know how to create their own fresh water supply.
These wells aren't intended for people.
The Samburu have walked over 100 miles so that their livestock can survive the dry season.
With multiple wells and sometimes hundreds of cows, it's important to keep organized.
So each herder manages his own well and sings his own unique song.
And remarkably, each cow has learned to recognize their owner's tune.
They're coming right to his well if they recognize his song.
So, in this well, there's one song, in that well, there's a slightly different song, and so on and so forth.
So every group of cows knows their owner's song.
They're musical cows.
When the livestock have had enough, the Samburu herd them away in search for grass.
When the people are gone, the wildlife take over the wells once more.
These elephants wouldn't survive here if it weren't for the Samburu.
But equally, the Samburu need the elephants.
These giants will eat enough trees and shrubs to help keep the land open for livestock grazing.
By bringing water to the surface, humans make it possible for even the biggest wild animals to survive in a dry land.
And it's not just in dry areas.
Further south, in Africa's Rift Valley, you find some of the largest freshwater lakes on the planet.
And here, too, humans and wildlife are inextricably linked.
We've just discovered that one tiny fish in particular is all that stands between us and a deadly disease.
Larger than the state of Maryland, and nearly twice as deep as the Empire State Building, Lake Malawi is an evolutionary wonder.
I'm in the most diverse spot on Earth for freshwater fish.
Maybe 5% of all freshwater fish on the entire planet are found in this one lake, Lake Malawi.
You just don't expect it.
You just don't expect to come to a fresh water lake and to see what you might see in the greatest coral reefs on Earth.
The vast majority of these fish belong to a single family called cichlids.
Cichlids are famous for rapidly evolving into new species, each with a new and sometimes bizarre strategy for survival.
Like most cichlids, this one is a mouthbrooder, whose babies know that the safest place is inside their parent's jaws.
And this is the playing-dead fish.
Curious scavengers who get too close are in for a surprise.
My personal favorite is a fish who builds sand castles.
This incredible arena has been built by a fish.
And there he is.
That's a bower-builder.
That's the guy who makes this incredible bower.
It's basically a stadium for him to just one thing, and that is display to a female.
The bigger your stadium, the bigger your arena, or bower, the more likely it is that a female will find you attractive.
There's something in that, I guess.
A bit like California.
My fingers are being nibbled by little cichlids.
Look at this! This is amazing! I'm looking at this construction fish on one side, and then I'm having a manicure on the other side.
The evolution of cichlids in Lake Malawi is one of the great wonders of the natural world.
And for humans, these cichlids also provide food and income.
Fishermen here feed an estimated 20 million people with their catch.
And one cichlid in particular keeps the lake free from disease, a fact we only discovered the hard way.
In the 1980s, two deadly epidemics devastated this freshwater paradise.
First, World Health experts noticed that HIV spread faster here than anywhere else.
They then discovered this was because the lake shore had suddenly been infested by bilharzia.
The disease bilharzia is caused by a parasitic fluke that swims in the water and burrows through human skin.
It breeds in your liver, damaging organs, and introduces blood into your urine.
And this makes people with bilharzia more likely to contract HIV.
The sudden appearance of bilharzia was a mystery until a university professor studying fish made a key discovery.
Jay Staufer was observing cichlids when the epidemic struck.
In 1988, family members got it, I got it, my most of my crew contracted bilharzia, from swimming just in the open waters.
Jay had learnt that the bilharzia flukes were carried by a freshwater snail that had invaded shallow water.
This little guy controls the fate of many tens of thousands of people who live around this lake.
When this snail becomes predominant, so does bilharzia.
But where had the snail come from? The answer involves a cichlid with a rather special diet.
Look, look, look, look, look! There's a pair of them.
A female and a male.
And that's the fish that I'm after.
That's the placodon.
And this fish might hold the key to saving the people of this lake.
Placodon has jaws designed to crack open snail shells.
And by patrolling the shallows in large numbers, it kept the shoreline snail-free.
Before the 1980s, fishermen rarely fished for placodon because the real bounty lay in deep water.
But then famines in Africa drove them to fish so hard that deep water stocks collapsed.
Desperate, fishermen turned to the shallows, and placodon were swept up in their nets.
When I first started diving here in 1983, you couldn't snorkel or put a facemask on in shallow water and not see a placodon.
Now you really have to work to see placodon at all.
Without the snail-eating fish, the snails and bilharzia spread like wildfire.
Do the folks here know about these snail-eating fish? - Absolutely.
- They do? These people know about the snail-eating fishes, but the point is, you make the decision-- Do I go to bed tonight hungry or maybe catch a disease eight weeks from now? Hunger is a driving force, a powerful force.
Yeah.
The situation here is critical, but at least now we know how to make it better.
The village has a plan to build fish farms so that people don't have to fish the shallows, and hopefully placodon can recover.
If we can save the fish in this lake, then the people here will be healthier.
And that story can be told about nature everywhere.
Give nature a helping hand, and people will benefit from it.
Back in the desert, one man gave nature a helping hand and ended up helping feed a nation.
The Sahel is the southern border of the Sahara desert, stretching right across Africa.
All living things here await the arrival of rain.
Water has a pulse-- a time when it's plentiful and a time when it's absent.
In the Sahel, this pulse is erratic.
In the past half-century, due to climate change and poor land management, the desert has swallowed vast amounts of the Sahel, causing some of the worst famines in recent memory.
The village of Gourga was all but destroyed by the desert until one man took a stand.
Yacouba Sawadogo has no formal science education.
Yet what he has managed to achieve stunned the world.
He's stopped the desert.
Nearly 40 years ago, after a bad famine, Yacouba started farming in the height of the dry season, when nothing grows.
Because he was ignoring common sense, everyone, including the local chief, thought Yacouba was insane.
People criticized you before, saying what you were doing wasn't good and that it was against the rules.
They said it was madness, that you were going crazy.
They said that I was damaging tradition.
These words didn't hurt me.
The head of my own family said the same thing, and everybody laughed, but I kept my mouth shut.
The young Yacouba realized that before the rains came, he had to be ready to capture as much water in the soil as possible.
Chopping through the concrete-like earth, Yacouba dug wide holes and filled them up with dung and litter.
In fact, he was recruiting an unusual ally.
The dung attracted termites, who started using Yacouba's pits to grow the fungus that is their staple diet.
And in doing so, they dug a network of tiny tunnels in the soil, which served Yacouba's aims.
When the rains come, the tunnels in the termite nest retain the water, stopping it from running off.
The water runs into the tunnels and stays there, and the soil is greatly improved.
When the rains finally came, Yacouba fought for every drop of water.
He built low walls to slow the runoff of rain from his fields.
And instead of just planting crops, Yacouba also planted trees.
Locals remained hostile, calling Yacouba the village idiot.
But Yacouba persevered, and gradually, his alliance with wild plants and animals paid off.
Over four decades, the trees he planted encouraged birds that brought with them seeds for even more trees.
Yacouba's desert started looking more like a forest.
This is my very first tree.
I planted it here 38 years ago.
It's impossible to fully appreciate its importance.
Trees pump life into the world.
Yacouba's forest transforms the microclimate.
It locks wind and provides shade.
And crucially, it raises the water table, holding life-giving water in the soil.
Nearby, Yacouba's crops are also flourishing.
And he's no longer the village idiot.
Yacouba is the local hero.
During harvest time, the whole village joins him to gather millet.
They grow enough food to feed everyone.
Yacouba's ideas have been so successful, his methods are now taught across the Sahel, and his ideas are credited with helping Niger through a recent famine.
With help from the smallest creatures, a single farmer can harness the natural pulse of water.
Since the dawn of civilization, this ability to manipulate fresh water has been a key to our success as a species.
We learned to irrigate.
Harnessing gravity, we fed our cities.
And over the centuries, our control of the world's fresh water has only grown.
We can use water to power our world.
We can even move entire rivers uphill over vast distances.
But if we ignore nature and take too much water for our own use, it can end up in a disaster.
Like here, where our aggressive use of water unleashed forces beyond our control and caused one of the worst environmental disasters ever wrought by man.
Just decades ago, Moynaq, Uzbekistan was the principal harbor on the fourth largest fresh water lake on Earth.
So large, they called it a sea.
But today, the local kids here have never even seen the water.
What remains of the lake lies 100 miles from here.
The Aral Sea was half the size of England.
A fleet of fishing ships hauled around 10,000 tons of fish from its waters every year.
In any other place, I would think, "Wow, this is a magnificent set of sand dunes.
" But then you come across this, you come across the rusting hulk of ships, you come across these beached whales, and you realize that the sea was really right here.
And in my lifetime, certainly, it was right where I'm standing.
It's kind of hard to fathom.
When a lake this size disappears, it should take millennia, not decades.
So how did it happen? To get the full picture, I need to find what's left of the water.
That's easier said than done.
Film crews are not welcome in this former Soviet Republic.
There might be a couple of guys up here.
Um We go undercover as tourists.
Yeah, there are a couple of guys, so you might want to just keep the thing down.
The government here is sensitive Here we go.
That-- that is what it's all about.
And denies forcing school kids to work on cotton fields.
That's it right here.
A ball of cotton right in my hand.
Cotton is the reason the aral sea is dry today.
In the 1960s, the Soviet leaders wanted this region to become the world's leading exporter of this "white gold".
So engineers diverted the two great rivers that feed the Aral Sea.
But drying the rivers alone doesn't explain the scale and pace of destruction.
We unleashed other forces, evidence of which should be at the water's edge if I can find it.
We've been probing into this dry lakebed further and further in, trying to hit water, and it's been hours and hours of driving on this kind of dry, flat emptiness.
100 miles later, we finally find it-- water.
Wow.
That's what it's supposed to look like.
All that land that we traversed was once this.
Ahh! My God.
The water itself contains evidence for what has happened here.
Oh, my God.
And if you taste this, this water it does not taste like any sea that I've ever tasted.
I mean, it is wretched.
It is so salty.
50 years ago, the Aral Sea was nearly fresh enough to drink.
Today, it's three times saltier than any ocean.
So what happened to all that fresh water? Through our actions, we literally pushed the sea over a tipping point, and a perfect storm of forces drained all the water and life out of this region.
The story begins in the 1970s, when Soviet engineers cut off the rivers for cotton.
With less water coming in, and the sun beating down, the sea begins to evaporate.
As the lake begins to drop, all the plants on the lakeshore now start to die.
Without that resistance, the wind just howls across this landscape.
The wind increases evaporation, and that means the lake level drops even faster.
It exposes the lakebed, and it leaves behind a crust of salt.
This salt is now picked up by the wind, and that poisons the soil and the plants up to 500 kilometers away from here.
And things keep getting worse.
The shrinking lake causes the climate to shift, winters get colder, and the summers even hotter.
The Aral Sea is now in a death spiral.
Less water, more salt, more wind.
From this nightmare, there really can't be any recovery.
The amount of water lost in just 40 years is simply staggering.
The water level is here now, but when I was born, it would've been way above my head, six stories above my head.
We won't be able to recover that fresh water anytime soon.
Nor are we likely to ever see the hundreds of species of fish, birds and mammals that vanished, some for all time.
I still somehow don't believe it, or don't want to believe it.
Because it's just too big.
Just too big.
The lesson that I'm taking home is this-- if we cut off the natural pulse of water across the land, watch out.
Because changes can be sudden and irreversible.
But surely nothing like this could happen in the wealthiest nation on Earth.
Or could it? The Colorado River has been dubbed the American Nile.
Our ingenious management of this water supports an estimated 36 million people in the driest part of North America.
Cities like Denver, Las Vegas, Phoenix and Los Angeles all depend on the Colorado.
But like the Aral Sea, could we be pushing the Colorado towards a tipping point? To answer that, I plan to follow the river from the Grand Canyon to Mexico's Sea of Cortez.
About halfway down the river, the Glen Canyon Dam is just one of over 20 major dams on the Colorado.
Giant projects like this allow us to be in charge of the pulse of water instead of nature.
Let's go up here a little bit and take a look.
I'm dying to see over the edge of this thing.
Peter McBride, author and photographer, has spent the last four years studying the story of the Colorado.
I'm inclined to say it's a long, long way down there.
Pretty sure it's over 700 feet, the drop right here.
He's gonna guide me down the river to the ocean.
Holy Moses.
When I first started looking at this river, I didn't know what became of it, and nobody seems to know what happens downstream.
Everybody only worries about their water and upstream, but I've met engineers that have worked on major projects on this river, and they have no idea what happens at the end of the river.
No, I got it, I got it.
Below the Glen Canyon Dam, we enter the Grand Canyon.
I'm pretty sure this is Horseshoe Bend.
God, the scale is so big.
Do you love this river? Yeah.
I'm kind of alarmed at what's become of it, particularly downstream.
This river once cut a chasm through stone a mile deep.
Now, because of the dams, the river only has a fraction of its power.
Kayaking is much too slow, so we're going to drive part of the way.
Meet the beast.
After the Grand Canyon, we pass dozens of large water projects that divert the Colorado River.
Pumps push water uphill to Phoenix, Tucson and Los Angeles.
But in the Imperial Valley, we meet the biggest water user of all-- agriculture.
There it is.
There's the river.
All that water from the river? Yeah, over 70% of the river goes to the agriculture.
That water came right through the Grand Canyon.
We were on that water, and here it is, growing lettuce.
So this area produces the entire lettuce crop for the US in the winter months.
So, no matter where you live in the US, you actually eat the Colorado River.
You gotta eat.
Gotta have food.
By pouring water on one of the sunniest deserts in North America, we can grow greens even in deep winter.
It's a brilliant combination of solar energy and water.
Farmers here provide 80% of America's winter vegetables.
I'm gonna be-- This thing's getting heavier by the day.
But at what point do we know we're taking too much water away from the river? Wow! By the time the Colorado reaches Mexico, 90% of the water has been used up.
Looks really different down here.
You can't even believe it's the same river.
You know what's pretty hard to believe? This looks pretty clean right here.
Yeah.
Don't tell me.
But they say by the time we reach the border, it's been used eight times.
No, no, don't tell me that.
Why do you have to tell me that now? Really, I mean, this is a really beautiful place.
Why-- why are you-- That's inappropriate.
No, don't do that.
It's a little salty.
Dude, that is-- For the next 17 miles, the river is a border notorious for illegal immigration and drug trafficking.
What are you guys doing? We're just exploring the Colorado River.
Just to let you know real quick, this is the international border.
Behind us is Mexico.
This is the US.
Anybody here is allowed to go towards the Mexican side, as long as you don't make landfall or throw your anchor or get off and then come back.
That'll be an illegal entry.
Either way.
At some points, this river goes fully into Mexico, doesn't it? - That is correct.
- How far down? It's about 1/4 of a mile or less.
There's the Morelos Dam.
Hey, thanks a bunch.
You're welcome.
You guys be safe.
Thanks very much.
You guys do the same.
Beautiful.
The Morelos Dam in Mexico is the final diversion on the Colorado.
That's it, huh? Like, right there? That's it.
But why is it so low? There's not that much water.
By treaty, Mexico is entitled to use the final 10% of the river for its own agriculture.
You get all your gear? Yeah.
Yeah.
Beyond the Morelos Dam, our kayaks are too big for what remains of the river, so we switch to portable rafts.
We're still 100 miles from the Sea of Cortez.
This really-- I keep pinching myself that this is downstream on the Colorado.
Most rivers get bigger as you get closer to the sea, and this one gets smaller, you know? It's getting thin here.
100 years ago, steamships drove up this same channel.
Ohh! Really? Wow.
The river's gonna end at some point.
Look at that.
That looks like a real end to me.
Wow.
That's water from the Grand Canyon.
And it's like watching little baby sea turtles going to the sea right now.
It is just trying so hard.
It's never gonna make it.
It's got-- How far's it got? - 100 miles? - 100-plus.
It's got 100 miles to go, and that's just not gonna get us there.
It is beautiful, in a weird way.
It's like-- I actually don't want to leave this.
All of a sudden, it feels like a living thing to me.
And all of a sudden, it feels like it's got a mind of its own and it's trying to do something it's been doing for a few million years.
It's sort of weird to leave the river behind, in some strange way.
Okay.
As planned, we're going to follow the river's old path to the Sea of Cortez water or no water.
This was once the largest desert estuary in North America.
This is it.
This is a story about choice.
We've fed a nation, but at a price.
A century ago, this was a wetland nearly twice the size of the state of Rhode Island.
It was home to countless birds, mammals, even jaguars hunted here.
A community of 20,000 Native Americans fished and hunted in this delta.
All of it has dried up and vanished.
And what shocks me the most is that, like most people, I didn't even know that this was the choice I was making.
If the Grand Canyon dried up, people would come unglued.
There would be outrage.
Yet those same people have no idea that this is the same river that we're standing on right here.
This is the exact same river.
And that-- Part of me makes me a little outraged to a degree.
Like, how did we get to this point? The Colorado River flowed to the sea for six million years.
And not a single drop of it has reached the sea since the late '90s.
Not a drop of it.
- On our watch.
- On our watch.
It is genuinely hot down here.
It is baking.
What happened here is depressing.
I'm just hot, man.
I can't even think straight.
I'm gonna collapse.
But there is hope.
Just when I think I can't take any more walking, Pete's friend Will comes to the rescue.
- Is that him? - That's Will.
He takes us on a magical journey.
Because hidden in the middle of this dry delta lies an emerald jewel.
Wow, look at that.
A forgotten wetland called La Ciénega de Santa Clara.
All of a sudden, I feel like I'm on top of the Everglades.
I haven't seen that much water since the Grand Canyon.
This is what this whole area would looked like 100 years ago.
Wow.
Look at the birds down there.
La Ciénega is 40,000 acres of magnificent wetlands.
And though it's just a fraction of the original estuary, it's packed with wildlife, including several endangered species.
But what is most amazing about this place is how it got here.
La Ciénega is an accident.
In the 1970s, the agricultural industry to the north needed somewhere to pump water that was too salty and chemical-ridden for crops.
So they dug a ditch and dumped the water onto barren sand.
Over 30 years, nature worked a miracle.
Cattail seeds blew in on the wind and started to grow in the foul water.
Their roots pumped oxygen into the soil, which fed microbes that broke down the poisons.
In time, the water cleared, and soon birds began to nest in the reeds, and fish swam in the lagoons.
It cannot but leave you with just this enormous sense of possibility, of endless possibility.
Man, if this happens on an accident, imagine what could happen with a little bit of help, with a little bit of human ingenuity, with a little bit of forethought.
If you want to see what ingenuity and forethought can do for wildlife, look no further than the American heartland.
Are you seeing this? 80 years ago, the people of Missouri hatched a plan to save a natural wetland.
Today, the results are a spectacle that stretches from horizon to horizon.
These are snow geese, on their annual migration from the Gulf of Mexico up into Canada.
1.
2 million land in the lake behind me.
They'll stay here before continuing their journey north.
There's a spectacle here that, honestly, minute for minute, rivals the greatest things that I have ever seen in my life.
And it's all because people here, for 80 years, decided to let a little bit of water go for nature.
They just decided that they were going to share-- not share 50/50, share, like, 2% of the water for wildlife.
And because of that you have that.
The Squaw Creek National Wildlife Refuge was started in 1935, when local citizens grew concerned that America was losing its migratory birds.
Despite the country being in the midst of the Great Depression, they dug ditches and built dams.
Anywhere else, you'd imagine water projects like this being built for agriculture.
But here, this is actually for wildlife.
And you realize that all the engineering might that we have-- if, I guess, it were reversed-- can also benefit nature.
Among the chief beneficiaries of these water diversions is the bald eagle.
Over 150 bald eagles migrate to Squaw Creek because it is a good place for them to find food.
This juvenile hasn't yet developed its white head and golden beak.
But now it's time it learnt to hunt.
As soon as the eagle approaches, the geese take evasive action.
In the chaos, it's hard to tell friend from foe.
The juvenile learns to single out a particular goose.
It's a dogfight.
Snow geese have spectacular evasive maneuvers.
This goose injured its wing.
And that gives the eagle the chance it needs.
North America once had incredible concentrations of wildlife.
And Squaw Creek shows us that, with relatively little effort, we can bring some of it back.
All we need to do is engineer ways to restore that natural pulse of water.
Across America, there are dams that have outlived their usefulness.
Fire.
By removing them, we can reconnect the rivers to the sea.
Then species like salmon and steelhead can swim upstream to spawn.
And we don't always need to remove dams.
Sometimes all we need is a new perspective on how we use them.
On the Glen Canyon Dam, where I started my journey down the Colorado, engineers are releasing sudden pulses of water to mimic natural floods in spring.
The sudden surge flushes out sediments and creates the kind of riverbank habitat that existed naturally before the dam.
And just months after Pete and I walked the dry Colorado Delta, this happened.
Conservationists have convinced the Unites States and Mexico to let an annual pulse of water flow through the Morelos Dam down the Colorado.
For the first time in over a decade, the Colorado River has connected to the sea.
I've seen how, if we're not careful with water, we can set off a spiral of destruction.
But equally, by sharing our water with nature, we can spark an explosion of life.
And that gives me hope-- that water doesn't have to divide people from nature.
Water if shared, if we allow a little bit of that pulse go, can be that amazing place where humans and nature can find common ground.
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Yet one species is always missing from the picture.
Us.
I'm Dr.
M.
Sanjayan.
As a scientist and conservationist, I've dedicated the past 25 years of my life to studying and protecting the wildlife I love.
Hold on, buddy! Now, my mission is to tell you an untold story, where we humans are not separate from nature.
We are part of it.
And nowhere do we rely on nature more than in our thirst for water.
We've learned the hard way that if we disrupt the flow of water too much, both wildlife and humans can suffer.
I'm just hot, man.
I'm gonna collapse.
But on my journey, I'm discovering that by changing our perspective, we can restore the natural pulse of water.
Are you seeing this? The results can be extraordinary.
February 25h, 2015 In northern Kenya, for half the year, little or no rain will fall.
During this dry season, animals face a stark reality-- find water or die.
The trouble is, for hundreds of miles around, the rivers here run dry.
So wherever you find water like this, accessible from the surface, you will find the most amazing collection of wildlife.
This whole ecology of these areas, these dry areas, is based on water.
These elephants would not be here if not for the water.
They wouldn't be able to find enough to live out here.
Water is so vital, even natural enemies declare an uneasy truce when it comes to drinking.
But these watering holes wouldn't exist if it weren't for the actions of one particular species- us.
For centuries, people like these Samburu warriors have known a secret.
In certain spots beneath the sand, the bedrock forces the water close to the surface.
So when the rest of East Africa lies parched, here they know how to create their own fresh water supply.
These wells aren't intended for people.
The Samburu have walked over 100 miles so that their livestock can survive the dry season.
With multiple wells and sometimes hundreds of cows, it's important to keep organized.
So each herder manages his own well and sings his own unique song.
And remarkably, each cow has learned to recognize their owner's tune.
They're coming right to his well if they recognize his song.
So, in this well, there's one song, in that well, there's a slightly different song, and so on and so forth.
So every group of cows knows their owner's song.
They're musical cows.
When the livestock have had enough, the Samburu herd them away in search for grass.
When the people are gone, the wildlife take over the wells once more.
These elephants wouldn't survive here if it weren't for the Samburu.
But equally, the Samburu need the elephants.
These giants will eat enough trees and shrubs to help keep the land open for livestock grazing.
By bringing water to the surface, humans make it possible for even the biggest wild animals to survive in a dry land.
And it's not just in dry areas.
Further south, in Africa's Rift Valley, you find some of the largest freshwater lakes on the planet.
And here, too, humans and wildlife are inextricably linked.
We've just discovered that one tiny fish in particular is all that stands between us and a deadly disease.
Larger than the state of Maryland, and nearly twice as deep as the Empire State Building, Lake Malawi is an evolutionary wonder.
I'm in the most diverse spot on Earth for freshwater fish.
Maybe 5% of all freshwater fish on the entire planet are found in this one lake, Lake Malawi.
You just don't expect it.
You just don't expect to come to a fresh water lake and to see what you might see in the greatest coral reefs on Earth.
The vast majority of these fish belong to a single family called cichlids.
Cichlids are famous for rapidly evolving into new species, each with a new and sometimes bizarre strategy for survival.
Like most cichlids, this one is a mouthbrooder, whose babies know that the safest place is inside their parent's jaws.
And this is the playing-dead fish.
Curious scavengers who get too close are in for a surprise.
My personal favorite is a fish who builds sand castles.
This incredible arena has been built by a fish.
And there he is.
That's a bower-builder.
That's the guy who makes this incredible bower.
It's basically a stadium for him to just one thing, and that is display to a female.
The bigger your stadium, the bigger your arena, or bower, the more likely it is that a female will find you attractive.
There's something in that, I guess.
A bit like California.
My fingers are being nibbled by little cichlids.
Look at this! This is amazing! I'm looking at this construction fish on one side, and then I'm having a manicure on the other side.
The evolution of cichlids in Lake Malawi is one of the great wonders of the natural world.
And for humans, these cichlids also provide food and income.
Fishermen here feed an estimated 20 million people with their catch.
And one cichlid in particular keeps the lake free from disease, a fact we only discovered the hard way.
In the 1980s, two deadly epidemics devastated this freshwater paradise.
First, World Health experts noticed that HIV spread faster here than anywhere else.
They then discovered this was because the lake shore had suddenly been infested by bilharzia.
The disease bilharzia is caused by a parasitic fluke that swims in the water and burrows through human skin.
It breeds in your liver, damaging organs, and introduces blood into your urine.
And this makes people with bilharzia more likely to contract HIV.
The sudden appearance of bilharzia was a mystery until a university professor studying fish made a key discovery.
Jay Staufer was observing cichlids when the epidemic struck.
In 1988, family members got it, I got it, my most of my crew contracted bilharzia, from swimming just in the open waters.
Jay had learnt that the bilharzia flukes were carried by a freshwater snail that had invaded shallow water.
This little guy controls the fate of many tens of thousands of people who live around this lake.
When this snail becomes predominant, so does bilharzia.
But where had the snail come from? The answer involves a cichlid with a rather special diet.
Look, look, look, look, look! There's a pair of them.
A female and a male.
And that's the fish that I'm after.
That's the placodon.
And this fish might hold the key to saving the people of this lake.
Placodon has jaws designed to crack open snail shells.
And by patrolling the shallows in large numbers, it kept the shoreline snail-free.
Before the 1980s, fishermen rarely fished for placodon because the real bounty lay in deep water.
But then famines in Africa drove them to fish so hard that deep water stocks collapsed.
Desperate, fishermen turned to the shallows, and placodon were swept up in their nets.
When I first started diving here in 1983, you couldn't snorkel or put a facemask on in shallow water and not see a placodon.
Now you really have to work to see placodon at all.
Without the snail-eating fish, the snails and bilharzia spread like wildfire.
Do the folks here know about these snail-eating fish? - Absolutely.
- They do? These people know about the snail-eating fishes, but the point is, you make the decision-- Do I go to bed tonight hungry or maybe catch a disease eight weeks from now? Hunger is a driving force, a powerful force.
Yeah.
The situation here is critical, but at least now we know how to make it better.
The village has a plan to build fish farms so that people don't have to fish the shallows, and hopefully placodon can recover.
If we can save the fish in this lake, then the people here will be healthier.
And that story can be told about nature everywhere.
Give nature a helping hand, and people will benefit from it.
Back in the desert, one man gave nature a helping hand and ended up helping feed a nation.
The Sahel is the southern border of the Sahara desert, stretching right across Africa.
All living things here await the arrival of rain.
Water has a pulse-- a time when it's plentiful and a time when it's absent.
In the Sahel, this pulse is erratic.
In the past half-century, due to climate change and poor land management, the desert has swallowed vast amounts of the Sahel, causing some of the worst famines in recent memory.
The village of Gourga was all but destroyed by the desert until one man took a stand.
Yacouba Sawadogo has no formal science education.
Yet what he has managed to achieve stunned the world.
He's stopped the desert.
Nearly 40 years ago, after a bad famine, Yacouba started farming in the height of the dry season, when nothing grows.
Because he was ignoring common sense, everyone, including the local chief, thought Yacouba was insane.
People criticized you before, saying what you were doing wasn't good and that it was against the rules.
They said it was madness, that you were going crazy.
They said that I was damaging tradition.
These words didn't hurt me.
The head of my own family said the same thing, and everybody laughed, but I kept my mouth shut.
The young Yacouba realized that before the rains came, he had to be ready to capture as much water in the soil as possible.
Chopping through the concrete-like earth, Yacouba dug wide holes and filled them up with dung and litter.
In fact, he was recruiting an unusual ally.
The dung attracted termites, who started using Yacouba's pits to grow the fungus that is their staple diet.
And in doing so, they dug a network of tiny tunnels in the soil, which served Yacouba's aims.
When the rains come, the tunnels in the termite nest retain the water, stopping it from running off.
The water runs into the tunnels and stays there, and the soil is greatly improved.
When the rains finally came, Yacouba fought for every drop of water.
He built low walls to slow the runoff of rain from his fields.
And instead of just planting crops, Yacouba also planted trees.
Locals remained hostile, calling Yacouba the village idiot.
But Yacouba persevered, and gradually, his alliance with wild plants and animals paid off.
Over four decades, the trees he planted encouraged birds that brought with them seeds for even more trees.
Yacouba's desert started looking more like a forest.
This is my very first tree.
I planted it here 38 years ago.
It's impossible to fully appreciate its importance.
Trees pump life into the world.
Yacouba's forest transforms the microclimate.
It locks wind and provides shade.
And crucially, it raises the water table, holding life-giving water in the soil.
Nearby, Yacouba's crops are also flourishing.
And he's no longer the village idiot.
Yacouba is the local hero.
During harvest time, the whole village joins him to gather millet.
They grow enough food to feed everyone.
Yacouba's ideas have been so successful, his methods are now taught across the Sahel, and his ideas are credited with helping Niger through a recent famine.
With help from the smallest creatures, a single farmer can harness the natural pulse of water.
Since the dawn of civilization, this ability to manipulate fresh water has been a key to our success as a species.
We learned to irrigate.
Harnessing gravity, we fed our cities.
And over the centuries, our control of the world's fresh water has only grown.
We can use water to power our world.
We can even move entire rivers uphill over vast distances.
But if we ignore nature and take too much water for our own use, it can end up in a disaster.
Like here, where our aggressive use of water unleashed forces beyond our control and caused one of the worst environmental disasters ever wrought by man.
Just decades ago, Moynaq, Uzbekistan was the principal harbor on the fourth largest fresh water lake on Earth.
So large, they called it a sea.
But today, the local kids here have never even seen the water.
What remains of the lake lies 100 miles from here.
The Aral Sea was half the size of England.
A fleet of fishing ships hauled around 10,000 tons of fish from its waters every year.
In any other place, I would think, "Wow, this is a magnificent set of sand dunes.
" But then you come across this, you come across the rusting hulk of ships, you come across these beached whales, and you realize that the sea was really right here.
And in my lifetime, certainly, it was right where I'm standing.
It's kind of hard to fathom.
When a lake this size disappears, it should take millennia, not decades.
So how did it happen? To get the full picture, I need to find what's left of the water.
That's easier said than done.
Film crews are not welcome in this former Soviet Republic.
There might be a couple of guys up here.
Um We go undercover as tourists.
Yeah, there are a couple of guys, so you might want to just keep the thing down.
The government here is sensitive Here we go.
That-- that is what it's all about.
And denies forcing school kids to work on cotton fields.
That's it right here.
A ball of cotton right in my hand.
Cotton is the reason the aral sea is dry today.
In the 1960s, the Soviet leaders wanted this region to become the world's leading exporter of this "white gold".
So engineers diverted the two great rivers that feed the Aral Sea.
But drying the rivers alone doesn't explain the scale and pace of destruction.
We unleashed other forces, evidence of which should be at the water's edge if I can find it.
We've been probing into this dry lakebed further and further in, trying to hit water, and it's been hours and hours of driving on this kind of dry, flat emptiness.
100 miles later, we finally find it-- water.
Wow.
That's what it's supposed to look like.
All that land that we traversed was once this.
Ahh! My God.
The water itself contains evidence for what has happened here.
Oh, my God.
And if you taste this, this water it does not taste like any sea that I've ever tasted.
I mean, it is wretched.
It is so salty.
50 years ago, the Aral Sea was nearly fresh enough to drink.
Today, it's three times saltier than any ocean.
So what happened to all that fresh water? Through our actions, we literally pushed the sea over a tipping point, and a perfect storm of forces drained all the water and life out of this region.
The story begins in the 1970s, when Soviet engineers cut off the rivers for cotton.
With less water coming in, and the sun beating down, the sea begins to evaporate.
As the lake begins to drop, all the plants on the lakeshore now start to die.
Without that resistance, the wind just howls across this landscape.
The wind increases evaporation, and that means the lake level drops even faster.
It exposes the lakebed, and it leaves behind a crust of salt.
This salt is now picked up by the wind, and that poisons the soil and the plants up to 500 kilometers away from here.
And things keep getting worse.
The shrinking lake causes the climate to shift, winters get colder, and the summers even hotter.
The Aral Sea is now in a death spiral.
Less water, more salt, more wind.
From this nightmare, there really can't be any recovery.
The amount of water lost in just 40 years is simply staggering.
The water level is here now, but when I was born, it would've been way above my head, six stories above my head.
We won't be able to recover that fresh water anytime soon.
Nor are we likely to ever see the hundreds of species of fish, birds and mammals that vanished, some for all time.
I still somehow don't believe it, or don't want to believe it.
Because it's just too big.
Just too big.
The lesson that I'm taking home is this-- if we cut off the natural pulse of water across the land, watch out.
Because changes can be sudden and irreversible.
But surely nothing like this could happen in the wealthiest nation on Earth.
Or could it? The Colorado River has been dubbed the American Nile.
Our ingenious management of this water supports an estimated 36 million people in the driest part of North America.
Cities like Denver, Las Vegas, Phoenix and Los Angeles all depend on the Colorado.
But like the Aral Sea, could we be pushing the Colorado towards a tipping point? To answer that, I plan to follow the river from the Grand Canyon to Mexico's Sea of Cortez.
About halfway down the river, the Glen Canyon Dam is just one of over 20 major dams on the Colorado.
Giant projects like this allow us to be in charge of the pulse of water instead of nature.
Let's go up here a little bit and take a look.
I'm dying to see over the edge of this thing.
Peter McBride, author and photographer, has spent the last four years studying the story of the Colorado.
I'm inclined to say it's a long, long way down there.
Pretty sure it's over 700 feet, the drop right here.
He's gonna guide me down the river to the ocean.
Holy Moses.
When I first started looking at this river, I didn't know what became of it, and nobody seems to know what happens downstream.
Everybody only worries about their water and upstream, but I've met engineers that have worked on major projects on this river, and they have no idea what happens at the end of the river.
No, I got it, I got it.
Below the Glen Canyon Dam, we enter the Grand Canyon.
I'm pretty sure this is Horseshoe Bend.
God, the scale is so big.
Do you love this river? Yeah.
I'm kind of alarmed at what's become of it, particularly downstream.
This river once cut a chasm through stone a mile deep.
Now, because of the dams, the river only has a fraction of its power.
Kayaking is much too slow, so we're going to drive part of the way.
Meet the beast.
After the Grand Canyon, we pass dozens of large water projects that divert the Colorado River.
Pumps push water uphill to Phoenix, Tucson and Los Angeles.
But in the Imperial Valley, we meet the biggest water user of all-- agriculture.
There it is.
There's the river.
All that water from the river? Yeah, over 70% of the river goes to the agriculture.
That water came right through the Grand Canyon.
We were on that water, and here it is, growing lettuce.
So this area produces the entire lettuce crop for the US in the winter months.
So, no matter where you live in the US, you actually eat the Colorado River.
You gotta eat.
Gotta have food.
By pouring water on one of the sunniest deserts in North America, we can grow greens even in deep winter.
It's a brilliant combination of solar energy and water.
Farmers here provide 80% of America's winter vegetables.
I'm gonna be-- This thing's getting heavier by the day.
But at what point do we know we're taking too much water away from the river? Wow! By the time the Colorado reaches Mexico, 90% of the water has been used up.
Looks really different down here.
You can't even believe it's the same river.
You know what's pretty hard to believe? This looks pretty clean right here.
Yeah.
Don't tell me.
But they say by the time we reach the border, it's been used eight times.
No, no, don't tell me that.
Why do you have to tell me that now? Really, I mean, this is a really beautiful place.
Why-- why are you-- That's inappropriate.
No, don't do that.
It's a little salty.
Dude, that is-- For the next 17 miles, the river is a border notorious for illegal immigration and drug trafficking.
What are you guys doing? We're just exploring the Colorado River.
Just to let you know real quick, this is the international border.
Behind us is Mexico.
This is the US.
Anybody here is allowed to go towards the Mexican side, as long as you don't make landfall or throw your anchor or get off and then come back.
That'll be an illegal entry.
Either way.
At some points, this river goes fully into Mexico, doesn't it? - That is correct.
- How far down? It's about 1/4 of a mile or less.
There's the Morelos Dam.
Hey, thanks a bunch.
You're welcome.
You guys be safe.
Thanks very much.
You guys do the same.
Beautiful.
The Morelos Dam in Mexico is the final diversion on the Colorado.
That's it, huh? Like, right there? That's it.
But why is it so low? There's not that much water.
By treaty, Mexico is entitled to use the final 10% of the river for its own agriculture.
You get all your gear? Yeah.
Yeah.
Beyond the Morelos Dam, our kayaks are too big for what remains of the river, so we switch to portable rafts.
We're still 100 miles from the Sea of Cortez.
This really-- I keep pinching myself that this is downstream on the Colorado.
Most rivers get bigger as you get closer to the sea, and this one gets smaller, you know? It's getting thin here.
100 years ago, steamships drove up this same channel.
Ohh! Really? Wow.
The river's gonna end at some point.
Look at that.
That looks like a real end to me.
Wow.
That's water from the Grand Canyon.
And it's like watching little baby sea turtles going to the sea right now.
It is just trying so hard.
It's never gonna make it.
It's got-- How far's it got? - 100 miles? - 100-plus.
It's got 100 miles to go, and that's just not gonna get us there.
It is beautiful, in a weird way.
It's like-- I actually don't want to leave this.
All of a sudden, it feels like a living thing to me.
And all of a sudden, it feels like it's got a mind of its own and it's trying to do something it's been doing for a few million years.
It's sort of weird to leave the river behind, in some strange way.
Okay.
As planned, we're going to follow the river's old path to the Sea of Cortez water or no water.
This was once the largest desert estuary in North America.
This is it.
This is a story about choice.
We've fed a nation, but at a price.
A century ago, this was a wetland nearly twice the size of the state of Rhode Island.
It was home to countless birds, mammals, even jaguars hunted here.
A community of 20,000 Native Americans fished and hunted in this delta.
All of it has dried up and vanished.
And what shocks me the most is that, like most people, I didn't even know that this was the choice I was making.
If the Grand Canyon dried up, people would come unglued.
There would be outrage.
Yet those same people have no idea that this is the same river that we're standing on right here.
This is the exact same river.
And that-- Part of me makes me a little outraged to a degree.
Like, how did we get to this point? The Colorado River flowed to the sea for six million years.
And not a single drop of it has reached the sea since the late '90s.
Not a drop of it.
- On our watch.
- On our watch.
It is genuinely hot down here.
It is baking.
What happened here is depressing.
I'm just hot, man.
I can't even think straight.
I'm gonna collapse.
But there is hope.
Just when I think I can't take any more walking, Pete's friend Will comes to the rescue.
- Is that him? - That's Will.
He takes us on a magical journey.
Because hidden in the middle of this dry delta lies an emerald jewel.
Wow, look at that.
A forgotten wetland called La Ciénega de Santa Clara.
All of a sudden, I feel like I'm on top of the Everglades.
I haven't seen that much water since the Grand Canyon.
This is what this whole area would looked like 100 years ago.
Wow.
Look at the birds down there.
La Ciénega is 40,000 acres of magnificent wetlands.
And though it's just a fraction of the original estuary, it's packed with wildlife, including several endangered species.
But what is most amazing about this place is how it got here.
La Ciénega is an accident.
In the 1970s, the agricultural industry to the north needed somewhere to pump water that was too salty and chemical-ridden for crops.
So they dug a ditch and dumped the water onto barren sand.
Over 30 years, nature worked a miracle.
Cattail seeds blew in on the wind and started to grow in the foul water.
Their roots pumped oxygen into the soil, which fed microbes that broke down the poisons.
In time, the water cleared, and soon birds began to nest in the reeds, and fish swam in the lagoons.
It cannot but leave you with just this enormous sense of possibility, of endless possibility.
Man, if this happens on an accident, imagine what could happen with a little bit of help, with a little bit of human ingenuity, with a little bit of forethought.
If you want to see what ingenuity and forethought can do for wildlife, look no further than the American heartland.
Are you seeing this? 80 years ago, the people of Missouri hatched a plan to save a natural wetland.
Today, the results are a spectacle that stretches from horizon to horizon.
These are snow geese, on their annual migration from the Gulf of Mexico up into Canada.
1.
2 million land in the lake behind me.
They'll stay here before continuing their journey north.
There's a spectacle here that, honestly, minute for minute, rivals the greatest things that I have ever seen in my life.
And it's all because people here, for 80 years, decided to let a little bit of water go for nature.
They just decided that they were going to share-- not share 50/50, share, like, 2% of the water for wildlife.
And because of that you have that.
The Squaw Creek National Wildlife Refuge was started in 1935, when local citizens grew concerned that America was losing its migratory birds.
Despite the country being in the midst of the Great Depression, they dug ditches and built dams.
Anywhere else, you'd imagine water projects like this being built for agriculture.
But here, this is actually for wildlife.
And you realize that all the engineering might that we have-- if, I guess, it were reversed-- can also benefit nature.
Among the chief beneficiaries of these water diversions is the bald eagle.
Over 150 bald eagles migrate to Squaw Creek because it is a good place for them to find food.
This juvenile hasn't yet developed its white head and golden beak.
But now it's time it learnt to hunt.
As soon as the eagle approaches, the geese take evasive action.
In the chaos, it's hard to tell friend from foe.
The juvenile learns to single out a particular goose.
It's a dogfight.
Snow geese have spectacular evasive maneuvers.
This goose injured its wing.
And that gives the eagle the chance it needs.
North America once had incredible concentrations of wildlife.
And Squaw Creek shows us that, with relatively little effort, we can bring some of it back.
All we need to do is engineer ways to restore that natural pulse of water.
Across America, there are dams that have outlived their usefulness.
Fire.
By removing them, we can reconnect the rivers to the sea.
Then species like salmon and steelhead can swim upstream to spawn.
And we don't always need to remove dams.
Sometimes all we need is a new perspective on how we use them.
On the Glen Canyon Dam, where I started my journey down the Colorado, engineers are releasing sudden pulses of water to mimic natural floods in spring.
The sudden surge flushes out sediments and creates the kind of riverbank habitat that existed naturally before the dam.
And just months after Pete and I walked the dry Colorado Delta, this happened.
Conservationists have convinced the Unites States and Mexico to let an annual pulse of water flow through the Morelos Dam down the Colorado.
For the first time in over a decade, the Colorado River has connected to the sea.
I've seen how, if we're not careful with water, we can set off a spiral of destruction.
But equally, by sharing our water with nature, we can spark an explosion of life.
And that gives me hope-- that water doesn't have to divide people from nature.
Water if shared, if we allow a little bit of that pulse go, can be that amazing place where humans and nature can find common ground.
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