♪ ♪ ("Koyaaanisqatsi" by Courtney Hartman playing) ♪ Your breath is burning my skin ♪ ♪ Your mouth takes in my water ♪ ♪ And the clouds roll like a river ♪ ♪ The rain falls sharp as ice ♪ ♪ And the oceans tumble over like mist in the night ♪ ♪ And my heart is a machine, a machine keeping time ♪ ♪ And my body is a building scraping at the sky ♪ ♪ And water looks like water running ♪ ♪ Water looks like water running ♪ Funding is provided by The Arthur Vining Davis Foundations, Lynn Bay Dayton and Bruce C. Dayton, Anne Ray Foundation, and viewers like you.
Thank you.
(animals chittering) KELLY McEVERS: Probably because I use it every day, I take water for granted.
I'm Kelly McEvers, and I'm a radio journalist.
And for this story, I have teamed up with filmmakers and scientists to make a podcast-style documentary... (drop echoes) ...about what might be the most important substance on our planet: water.
And since embarking on this journey, I am now starting to see this molecule everywhere.
We call it the water lens.
Look through it, and you'll see water inside everything that lives.
(elephant trumpeting, birds twittering) You'll see rivers in the sky.
You'll even see water shaping human evolution.
You'll see water in the blueprint of civilization.
♪ ♪ (people talking, distant gunfire) You'll see water connected to changes and even conflicts across the world.
And for me, after seeing all this, I think one thing becomes clear... We really can't take water for granted anymore.
(wind whipping) (wind whipping continues) So, if there are endless ways to combine atoms to make molecules, what's so special about water?
STEPHEN MOJZSIS: Water is, of course, a molecule, but it is in the most... intense and intimate relationship with life that one can imagine.
McEVERS: Geologist Stephen Mojzsis speaks to the heart of this film.
♪ ♪ We need to understand this relationship between water and life because, to be blunt, our survival depends on it.
(steam hissing) ♪ ♪ Stephen is one of the many experts we met on our journey.
And his particular expertise takes us back to the very beginning of this story about water and life.
Stephen shocked the science world when he discovered where Earth's water came from.
MOJZSIS: We long held this idea-- a belief, really-- that water was delivered by comets and asteroids and so on.
But instead, what we found is that water was already here.
And we know this from the investigation of the very oldest minerals of all.
McEVERS: Stephen says water first showed up on the surface about 4.3 billion years ago.
So much of the surface was molten rock that we call this time the Hadean, which means "hell."
MOJZSIS: This is very much like what we might imagine the Hadean earth was like-- a bright red sky, that atmosphere is dominantly carbon dioxide.
Soon after it had finished its cooling, rocks and minerals released water as steam.
♪ ♪ It goes into the atmosphere, expands and cools, and as clouds then result in rain.
McEVERS: So began the first water cycle.
And it rained so much that two-thirds of our planet was submerged under water.
♪ ♪ This water has special powers.
MOJZSIS: Well, water is like the superhero of molecules.
Water is a really great solvent.
♪ ♪ McEVERS: We call it "the universal solvent" because it dissolves more substances than any other liquid.
And that meant our ancient oceans were this primordial soup of chemicals.
That is the crucible of life's origin.
McEVERS: We don't know for sure, but scientists think there was a spark.
And then... MOJZSIS: A water molecule is the link between the non-living and the living world.
♪ ♪ McEVERS: Stephen says the development of life could not have happened at a more crucial moment.
Because, at this time, Earth's atmosphere was mostly carbon dioxide, which acted like a blanket hugging the earth.
That heated things up and threatened to vaporize all our water.
♪ ♪ MOJZSIS: Earth's fate would have been a super-hothouse with a dense carbon dioxide atmosphere.
No water, no life.
Hellish surface.
McEVERS: But then, Stephen told me, early life evolved to rescue Earth from this scorching apocalypse.
Because a kind of bacteria photosynthesized the carbon dioxide out of the atmosphere.
And replaced it with...
The highly toxic substance called oxygen.
Now, that's ironic, because without oxygen, we can't... (inhales and exhales deeply) McEVERS: And it's this interplay between life and the atmosphere that continues to keep Earth at the perfect temperature-- not too hot, not too cold, just right for liquid water.
MOJZSIS: Life has actually perpetuated the liquid water on the surface of our planet for geologic time.
(helicopter blades churn) (indistinct talking over radio) McEVERS: Stephen has spent his career trying to find evidence of early life-forms and their watery origins, searching for fossils that might have survived for 3.8 billion years.
MOJZSIS (over radio): These rocks here to the east and north; they're called the Amitsoq, which is one of the most exciting places in the world to see the earliest evidence for life on our planet.
McEVERS: Almost all of the fossil rocks from such an ancient time have been churned up or weathered away.
This is one of the three places on Earth where the original sea beds still survive.
Stephen has traveled thousands of miles to see this single rock face.
Get the sun angled right.
There's a layer, here.
McEVERS: At first, it's hard to tell if Stephen is impressed... MOJZSIS: Look like a... McEVERS: And then... MOJZSIS: Holy (no audio).
I think... holy, holy, holy cow.
McEVERS: Stephen thinks he might be looking at the oldest life form ever found.
It'll take months of testing in a lab before Stephen can confirm that these markings were once living beings.
MOJZSIS: It's the kind of thing that many of us have been looking for for many, many, many years.
This is the ultimate search for a relative at the base of the family tree of all life itself.
McEVERS: Ever since, all life has been bound to water.
(water rushing) It is such a fundamental bond, no life can exist without it.
Even when life moved onto land, and the plants colonized the surface of the earth, even in the driest deserts, they still carry a little bit of the ocean with them.
♪ ♪ JILL FARRANT: All plants are 90 to 95% water in the first place.
And it's part of their structure, it's part of their metabolism, it's part of absolutely everything that they are.
♪ ♪ McEVERS: Vast regions of our world are getting hotter and drier.
For humans to adapt, it makes sense to study how nature overcomes the absence of water.
So, for 25 years, plant scientist Jill Farrant has championed a rare group of plants that can dry out and still come back to life.
FARRANT: So, this is a resurrection moss.
It rehydrates extremely quickly, it's gonna happen fast, so watch as I pour the water.
McEVERS: Mosses like this were among the first life forms to colonize dry land.
FARRANT: The plants that I work with are commonly called resurrection plants because they appear to resurrect from the dead state.
They're not dead at all; they're just so dry that they look dead.
But you just have to add water.
♪ ♪ McEVERS: Back in her lab in Cape Town, Jill is trying to discover how resurrection plants are able to break the sacred bond with water and still survive.
She wants to use this knowledge to help farmers get through droughts.
FARRANT: My dream is to create a crop that tolerates water loss and does not die and produce food security in the face of drought.
Where if there hasn't been rain and you get a rain, there's a guaranteed comeback of your crop.
All yours.
McEVERS: Imagine if a crop could resurrect in 24 hours the way the resurrection bush does.
FARRANT: Okay, let's pour some water on.
McEVERS: In its dry state, the bush transformed its insides into a glass-like substance.
♪ ♪ And now, as it rehydrates, these glassy tissues soften and come back to life.
♪ ♪ FARRANT: The strategy is extremely rare.
There are only 135 species in the world that can do this.
But in a drought-prone world, this strategy is a game-changer.
(birds chirping) McEVERS: Resurrection plants might be rare, but the genetic potential for resurrection is actually common.
It's in every plant that makes a seed.
Every single crop that we have makes a dry seed.
It has the genetics to be a resurrection plant, it just doesn't switch those genes on in face of a drought.
Let's actually just turn on those genes.
McEVERS: As water sources for crops become more and more erratic, Jill hopes she can develop her resurrection crop in time to save the world's most vulnerable farmers.
In the Northern Cape, Jill took our camera team to film a spectacular event that dramatically shows this ability of life to survive, even in the driest extremes.
Now, what fascinates me is this leaf.
Look at this one, eh?
It's going to... (chuckling): Yeah.
Purple juice.
And it's got this capsule, which all the seeds will erupt from.
McEVERS: Jill is introducing us to a secret desert bloom location where we might film the mass flowering of the desert.
FARRANT: There's so much life here.
It's dormant, and it's waiting.
But, you know, you're gonna have to have faith in the system that the rain's going to bring it around.
McEVERS: Christian Muñoz and his son-- also named Christiaan-- are time-lapse experts, and they have already spent decades chasing these elusive desert blooms.
CHRISTIAN MUÑOZ: Some people call us the plant hunters.
We want to show and to capture the change from the desert to the beautiful super blooms.
McEVERS: They use a computer-controlled camera, which means they can combine two shots, filmed at different times: once with the bloom, and once without.
The trouble is, there's at least a six-month gap between filming the two images.
And they're not just shooting in South Africa.
They are chasing super blooms all over the world.
The Muñoz's biggest challenge has been to film the bloom back home in Chile.
The Atacama Desert is the driest desert on Earth.
There are areas with no record of rain at all.
♪ ♪ Checking the weather radar, the Muñoz family has a reason to be hopeful.
CHRISTIAN MUÑOZ: Well, believe it or not, it is raining.
There's just a few drops but it looks like more rain is coming this way.
McEVERS: Sometimes a few drops is all it takes.
♪ ♪ Finally, after a decade of work, the Muñozes can show us the transformative power of water in a desert.
♪ ♪ ♪ ♪ (birds chirping) ♪ ♪ ♪ ♪ (birds chirping) Before they die, these flowers produce millions of seeds.
And with just a few molecules of water sealed inside each seed, these time-capsules of life can survive everything the desert throws at them.
We know of seeds that have sat for 30,000 years and still germinated when they finally got water.
Seeds, you know, seeds are-- I call them miracle technology.
Imagine if you had seeds of a Ferrari.
You know, human technology.
Ferrari, a nice car, beautiful, the object of desire of many people, and now you can buy a Ferrari that will arrive within an envelope through the mail.
And you get this seed you put in a pot with soil, you water it, and a few months later you have a Ferrari there.
Imagine-- imagine that.
And that's precisely what nature is doing quietly, silently, with a tree.
It started with a seed that weighed just a few grams.
And it's able to build it, the whole thing, from gas, water, and sunshine, right?
No, stop and think about this, what technology we have that match that?
(birds chirping) ♪ ♪ McEVERS: I have never met someone who loves trees as much as Antonio Nobre does.
He's not hugging the tree, he's listening to the water rising up through the trunk.
(wildlife calling in distance) (dull thudding) NOBRE: The leaves are pulling the water column, and it cavitates.
It makes tak-tak-tak-tak, and you can hear it on the stem, on the tree trunk.
(dull thudding) McEVERS: Antonio, a scientist at INPE-- Brazil's equivalent of NASA-- has dedicated his career to tracking the water molecule on its journey through the greatest forest on Earth.
(wildlife chittering) ♪ ♪ Antonio and his colleagues started by tracking the journey of the water rising through the trees, measuring the molecules as they are drawn 200 feet high into the canopy.
(insects chirping) Coloring the water with a U.V.
dye, scientists can even observe the flow of water through each individual leaf.
A rainforest tree can pump 260 gallons of water a day.
Heated by the sun, the water escapes as vapor into the sky.
But Antonio noticed that alongside water, the trees were also releasing something else.
Rising out of the forest, they measured tiny particles of dust-- so small they would be dwarfed by the spray from a perfume bottle.
NOBRE: Why trees are releasing this dust?
You know, this is like Sherlock Holmes, sort of, of mystery-- what is going on there?
McEVERS: Antonio and his team discovered the forest was conducting transactions in the air, creating its own cloud system.
Because every cloud and every raindrop is formed on a speck of dust.
(thunder rumbling) The technical term is "condensation nuclei," but Antonio gave it a name that I like a lot better.
It's like you're dropping magical dust, like fairy dust, and then pfff, it start raining.
McEVERS: Fairy dust is another seemingly magical expression of the bond between life and water.
It's like seeding the air, so that it would benefit itself.
♪ ♪ So, forest is cranking its own rain.
♪ ♪ McEVERS: Antonio's discovery immediately sparked a new mystery.
Everyone assumed that in the dry season, Amazon trees stop pumping water.
But that's not what happens.
NOBRE: The Amazon trees do something that is counter-intuitive.
They transpire more water during the dry season than during the wet season.
♪ ♪ The trees there are crazy.
But they don't care-- they, they just pump, pump, and pump.
They respond as a group.
McEVERS: And it's a big group.
400 billion trees pumping a staggering 20 billion tons of water each day into the sky.
It rises and condenses on fairy dust to make clouds.
And then all these clouds move like a river.
(wildlife chattering) Only this river is in the sky.
NOBRE: It captured the imagination; people said, "Wow, there are rivers in the sky?
How come?"
Well, it's a concentrated flow of moisture, and they bring moisture from point A to point B, like a river.
♪ ♪ McEVERS: Above the forest, the aerial river is even bigger than the Amazon River itself.
♪ ♪ You could think of this as the largest river on Earth.
And it flows far beyond the boundaries of the forest.
Blocked by the Andes mountains, it is forced to turn south, traveling 2,000 miles, beyond the city of Sao Paulo.
Dumping water as it goes, it transforms areas that should be deserts into fertile plains, and floods the prairies of the Pantanal, creating the largest wetland on Earth...
Which boasts the highest concentrations of wildlife in South America.
(birds squawking) So much water arrives that the usual rules for animals seem to be turned upside down.
Fish eat fruit from trees.
(water splashing) A tapir, having lost its meadows, grazes while holding its breath.
Even jaguars move from land and hunt in the water.
(birds chirping) ♪ ♪ (jaguar emits high-pitched grunts) ♪ ♪ The Amazon isn't the only flying river.
From the rainforests of Borneo to the African Congo, there are many forests with the power to shape global weather.
Combine this with the natural ebb and flow of the seasons and what you get is nature's great pulse.
NOBRE: This is ten years of data, of what plants are doing all... the whole biosphere.
Low productivity in red and yellow, and high productivity in green and blue.
This is showing you what the biosphere is all about.
Life... it's pulsating, like a heart... heartbeat.
McEVERS: Water is Earth's bloodstream.
And life is the result.
And now researchers are following the paths that water and life take together.
♪ ♪ (helicopter rotors beating) And new technology can open up an even greater understanding of how the movement of animals is connected to the pulse of water.
When we caught up with Martin Wikelski, he was busy putting a tracking device on a young giraffe.
But it's not just giraffe that he studies.
(crew conversing) Martin is actually coordinating a worldwide animal tracking revolution.
Martin's high-tech miniature tags can relay live feeds via the international space station to scientists anywhere in the world.
WIKELSKI: Well done!
(chuckles) Well, on animals we have these tiny little tags, that have a solar panel and a battery and electronics inside and an antenna.
And that can be as a backpack or it can be a little ear tag.
McEVERS: Martin even makes tags small enough for insects.
Like this death's-head hawkmoth.
(plane engine roars) With these smaller tags, Martin follows the signal from his airplane, downloading the tracks to his global maps.
WIKELSKI (over microphone): It's really amazing, this is the first time that we tracked, that anybody ever tracked any of these nocturnal moths, that we really know what they're doing.
This is completely new.
McEVERS: Martin is able to gather all this data from creatures big and small, into the Icarus database.
♪ ♪ Or, as some call it, "the internet of wings."
It gives him a live, global overview, where he can actually see how the patterns of animals connect with the pulse of water.
WIKELSKI: So, water is actually the most important thing.
In a lot of cases we see that water is driving migrations, movements or entire life histories of animals.
McEVERS: Wildebeest follow the rains as they sweep across the Serengeti.
(wildebeest braying) They know the rain will transform a desert into one of the richest grasslands on Earth.
♪ ♪ As they graze, these 1.4 million stomachs break down the grass and return the nutrients to the soil in the form of dung and urine.
And discoveries in the Serengeti reveal the greater the animal impact, the more the landscape is enriched and is able to hold even more water.
(birds squawking) The movement of animals can affect the landscape just as much as the movement of water does.
12 million snow geese seem to know the exact moment the snow will melt in the far north.
On their migration they disperse nutrients and seeds they have eaten across thousands of miles.
A lot of the movements we see here are related to water.
So we have the ice, when it melts... you see the snow geese going up from California.
The productivity of populations of animals, like geese in the Arctic, is highly dependent upon water.
So it's... it's really a system that drives almost everything.
McEVERS: Everything from great herds to tiny insects is perfectly synchronized with the pulse of water.
(birds squawking) (thunder roaring) But, for us, one story really stood out-- an incredible journey following water on a record-breaking adventure.
(birds chirping) Wandering glider dragonflies hatch in the rice paddies of India.
And as the monsoon rains sweep off the southern coast, the tiny insects rise 5,000 feet into the air, following the water far out into the Indian Ocean.
♪ ♪ The mystery of where the dragonflies go caught the attention of biologist Charles Anderson, when millions of wandering gliders suddenly appeared in the Maldives, 400 miles off the coast of India.
ANDERSON: I realized that something quite extraordinary was going on because dragonflies absolutely need fresh water to breed.
And Maldives is a place with no surface fresh water.
So, what on earth are they doing?
Why are they coming here, what on earth is going on?
McEVERS: Without breeding waters, flying all the way from India makes no sense.
Unless... the dragonflies were en route to somewhere else.
Remember those flying rivers over the Amazon?
In a similar way, the monsoon brings rain from India to Africa.
Charles tracked how the dragonflies were hitching a ride on these storms.
Incredibly, the tiny insects spend about a week flying 2,500 miles across the Indian Ocean... All the way to Africa.
ANDERSON: Most people cannot believe that a five centimeter insect could possibly cross an ocean.
And yet they do.
♪ ♪ McEVERS: The rains create temporary pools.
And the dragonflies arrive to be among the first to colonize them.
In the water, their nymphs prey on mosquito larvae.
♪ ♪ Within just seven weeks, they're ready to emerge and transform into adults.
The wandering gliders wait for the seasons to change.
A circuit of the Indian Ocean takes four generations to complete... A round-trip of 10,000 miles.
♪ ♪ (insects chirping, buzzing) ANDERSON: This is the-the largest, most amazing migration of any insect, in some ways of any animal.
To cross oceans, to pass between continents it is quite extraordinary.
McEVERS: Their relationship with water is extraordinary.
And, in Africa, they eat so many mosquitoes they can end up being the most effective way to control diseases, like malaria.
So imagine... what if farmers in India spray too many pesticides and kill the dragonflies?
It could cause a deadly malaria outbreak in Africa.
♪ ♪ WIKELSKI: We are really just at the beginning of a new phase of understanding Earth's systems because we finally get a glimpse of how life is moving and interacting around the planet, and this is super exciting to us.
♪ ♪ (thunder roaring) McEVERS: The pulse of water connects all the plants, all the forests, and all the animals.
But, of course, this pulse also connects you and me.
♪ ♪ Over seven billion of us depend on the pulse of water.
Our success as a species has been to harness the pulse.
We use water, above all, to feed ourselves.
But we now know that droughts are increasing in intensity-- becoming longer, breaking records.
The pulse of water might not be as reliable as we thought.
♪ ♪ ♪ ♪ On our travels across America, we met farmers who are experts at growing food in dry climates.
But for many of them, the most recent droughts have been overwhelming.
JIM LEDERHOS: There are folks that have run out of water.
And if there's no water here, there's no value.
There's no value at all.
PASTOR ON RADIO: All right, we're so thankful this morning for the rain that we've had.
I know here every drop counts, and we've been praying that drought is broken in West Texas.
KEVIN GOSS: After 2010 we've had a pretty good decline in rain and I've been stuck pretty dry for the most part for about the last nine years.
JEANNE GOSS: We try to sustain until we get rain, and if there's no rain then we have to sell.
MIKE CALLICRATE: So, the water table has dropped significantly in this area.
Without water, there's no livestock, there's no people.
McEVERS: It's not only farmers who suffer.
♪ ♪ Without water, entire communities are collapsing.
And it seems like nothing can be done... other than to pray.
GOSS: Heavenly Father, we thank you for this day, we thank you for the blessing.
We please ask that you keep the rainfall coming and let it nourish our pastures and nourish our crops.
ALL: Amen.
(lightning crackles) (airplane engine droning) Scientists have developed a unique technology to follow the droughts and to measure the amount of water held in the vegetation below.
SCIENTIST (on radio): If this is clear all to the... all the way to the end, you wanna continue down?
GREG ASNER (on radio): You're gonna run these.... how many miles down?
About ten to go.
Uh, yeah.
Yeah, the sand always clouds up.
McEVERS: They call Greg Asner "the drought chaser."
ASNER: We have found ourselves chasing these drought events.
And when I say chasing, it's somebody calling me up and saying, "Greg, we have this drought, can you come and help us to make that assessment?"
And it used to be that we'd get that call once a year and now I'm getting that call, I'm not kidding, at least once a month if not once a week.
McEVERS: Greg's technology can see and measure water in ways impossible with the naked eye.
As he flies over, lidar scanners use a laser to create a high-resolution 3D map of the forest below.
At the same time, Greg's cameras record a spectral image, which means they can see the chemical makeup of each tree, including the movement of water in the canopies.
In 2010, the drought chasers were called in to analyze a drought in the Amazon.
ASNER: We had this megadrought show up across a lot of the Amazon basin, especially in Brazil.
The imaging systems on board our plane were lighting up, literally the big screens were showing enormous amounts of loss.
And we saw this everywhere, all over the western Amazon.
We saw mortality that easily was over 50% of the tree canopy, and the reason this is alarming is that at any given moment in time, you would expect to see about one to two percent of the canopy in a state of dying, just naturally.
When you see 50%, 50 times the rate, you-you don't have words for it.
McEVERS: Scientists like Greg Asner believe if just 25% of the Amazon is lost, it will reach a tipping point that could fatally damage the rivers that fly above the forest.
People like Antonio Nobre think we're already there.
And in 2015 there were worrying signs he might be right.
2,000 miles away in Brazil's biggest city, Sao Paolo, the flying river had stopped its flow and the people were running out of water.
(protestors shouting) Antonio Nobre lives there.
The drought struck us, you know, head on, and... and I started getting really concerned.
The army start preparing for riots because, imagine, 22 million people in the largest Brazilian metropolis running out of water, and... people got so it was, like, "What are we going to do?
We don't have water, not even for drinking."
The only explanation is that we are damaging the Amazon.
You damage the forest, you damage the flying rivers, therefore you damage the water cycle, the pulses stop, it's like a heartbeat that all of a sudden stops.
McEVERS: While we were filming here we found one of the most unexpected effects of the Amazon drought on the Rio Tietê.
Normally, there's enough water to flush pollutants from Sao Paolo out to the sea.
But in the drought, the pollution intensifies.
Phosphates and industrial chemicals combine to create this toxic foam.
♪ ♪ To kayak here, you have to wear a biohazard suit.
It is the saddest image of a river I have ever seen.
Multiple organ failure-- you have that term in intensive care units.
Multiple organ failure, it's going on right now on the planet.
McEVERS: And that organ failure has been even more clear as the Amazon forest recently started to burn.
That connection between drought and fire is a story we know well where I live in California.
Our drought started in 2011 and lasted six years.
It got so bad the governor asked Greg Asner to come map its effects on our forests.
ASNER: This is a dramatic landscape where we're seeing, I would say, 30% are severely drought stricken and maybe 20% are surviving.
McEVERS: Greg estimates the drought in California killed 140 million trees.
Without moisture, the forests are like a tinderbox.
(siren blares) REPORTER: The famous Malibu coastline beneath a rising tower of smoke.
McEVERS: 2018 was the worst fire season in California's history, with over 8,500 fires burning close to two million acres and killing over a hundred people.
WOMAN: Oh my God, I don't know what to do.
Oh my God, I'm surrounded by fire and I don't know which way to go.
(sighs) Oh please, dear God... MAN: Oh, no way.
ASNER: So, you know, the system is changing, the water cycle is changing on us.
MAN: Yeah, it's time to go.
Those are really big, fundamental, planetary-scale changes that are affecting everybody.
McEVERS: Amidst all this destruction, Greg Asner remains hopeful.
Because, whenever he flies, he finds places that somehow manage to beat the drought.
He calls these places "refugia."
Whenever I've seen these massive losses, whether it's in the Amazon basin or in California or in the Pacific islands like Hawaii, we always have refugia emerge... as places of survival.
This is an example of a refugia, or a refuge, during the 2016 peak of the drought in California, and what you see here are mostly coastal redwood trees.
What defines this as a refuge is the fact that there was enough water on the landscape persisting in the soil to generate a sustained or resilient set of trees in this forest, and that's why they're showing up in blue.
♪ ♪ McEVERS: Protecting refugia protects water supplies of the future.
ASNER: To me those are the... the nuggets, the gold nuggets of nature that give me hope.
And not just hope, but literally the biological resource for re-expansion of those species.
The key is finding them and protecting them and allowing them to persist into the future.
♪ ♪ McEVERS: Our future is bound to water because of the intimate connection between life and the molecule that made us.
On Earth you have a paradise-- you have water in the liquid form for four billion years.
What is allowing for the water to remain on Earth?
It's life.
The take-home message here is that life is the key.
McEVERS: The pulse of water, moving across the Earth, is the very thing keeping our planet alive.
♪ ♪ But that pulse is changing.
Because of us.
And you don't have to be a scientist to realize what's at stake.
Even though our human world is vulnerable to these changes, what fascinates me is how resilient nature can be, if we give it a chance.
I realize now, it's not the water I was taking for granted... (thunder rumbling) but where it comes from.
It's nature we need to fight for, as if our lives depend on it.
Because they do.
Next time on "The Molecule that Made Us"-- episode two, "Civilizations."
An entire civilization ends here.
MAN: That's what we come from, a water-wading ape.
This is unbelievable.
To order "H2O: The Molecule That Made Us" on DVD, visit ShopPBS.org or call 1-800-PLAY-PBS.
This program is also available on Amazon Prime Video.
♪ ♪ Follow the story of water at pbs.org/molecule.
♪ ♪
