Connected: The Hidden Science of Everything (2020) s01e03 Episode Script
Dust
1
[energetic music playing]
[Nasser] Buckle up. I want to tell you
an epic story about life and death.
And the hero of this story is
the smallest of things.
It's everywhere,
but it's mostly invisible,
and it has secrets
that are even harder to see.
Secrets that connect space lasers,
a seaborne vacuum cleaner,
and the biggest bowl of salad on earth.
Secrets like how it defies death,
and how it's helping keep you
and virtually every living thing alive
right now.
To unlock all these secrets,
I need to travel to one of the most barren
and unforgiving places anywhere,
because that's the best place of all
to meet our unassuming hero.
This is a story about our dynamic
yet precarious planet,
where the littlest thing
can make the biggest difference.
-[music stops]
-[wind howling]
[upbeat music playing]
I'm Latif Nasser,
and this is a show about
the astonishing connections all around us,
connections between you and me
and our world
that'll make you see that world
in a whole new way.
[dramatic music playing]
This story begins
in the Central African nation of Chad.
So, it turns out
getting to the dustiest place
on planet Earth
is really, really difficult.
I've been traveling
for, like, three days now.
I flew into the capital city of Chad,
N'Djamena,
then from there
I flew into an oasis town in the north.
And from there, with Dr. Moussa here,
we're driving Whoa! [laughs]
We're driving a full day
straight into the Sahara Desert,
the hot, dry, bathroom-less Sahara Desert.
We are on our way
to a place called the Bodélé Depression
to look for a fish.
[energetic music playing]
We had to go with all of these soldiers
and paramedics
because if anything happened,
like if you get hurt,
there's nobody around to help you.
[wind blowing]
It's rare to go to a place
and be able to look in 360 degrees
and see nothing.
Like, this is the middle of the desert,
the middle of nowhere.
So, why am I on
a literal fishing expedition
in the Sahara Desert of all places?
Well, that fish is the starting point
to a global dust journey.
Ah!
Latif,
welcome in Bodélé.
-[Nasser] This is it?
-[Moussa] Yeah.
-[Nasser] Oh, wow.
-[Moussa] See!
Wow, it kind of just looks
like everything else.
[laughs]
[in French] It is the lake.
Everything you see in white,
-Yeah.
-it's the lake.
-[in English] Yeah. Oh, this is the lake?
-Yeah.
[dramatic music playing]
It's almost unimaginable now,
but that whole swath of desert
used to be underwater.
It was called Lake Mega-Chad.
At its peak, the lake was about the size
of modern-day Germany,
and it was as deep
as the Washington Monument is tall.
And it was full of fish
and teeming with life.
And then about a thousand years ago,
most of the lake abruptly dried up.
I cannot believe your job
is to look for fish in the Sahara Desert.
[Moussa in French]
Here when you look,
locals think you're looking for gold.
-Ah!
-I tell them, "No, it's not gold.
I'm a researcher."
But they don't believe me.
That's how it is.
We keep looking, looking, and looking.
[Nasser in English] What is
Is this like Is this a poop?
[Moussa in French] From a camel.
-[in English] Oh, that's camel poop.
-Yeah, camel.
Uh-huh.
-[Moussa in French] Let's keep looking.
-[Nasser] Mm-hm.
Dr. Moussa is one of the world experts
on Lake Mega-Chad.
What is that?
He's probably spent more time out here
than anyone.
I think it's a bullet.
Yeah, it's a bullet.
-In a gun?
-[Moussa] Yeah.
Oh my god. That's really big.
[Moussa in French] It's a 17 cartridge.
[imitates gun shooting]
People fight a bit.
Wow.
[Nasser in English] And then suddenly,
we find what we're actually looking for.
-[Nasser] Oh!
-Wow!
[Moussa in French] It's a beautiful piece!
[in English] What is it?
[in French] It's a catfish.
[in English] It's a catfish?
[in French] A catfish, yes.
[in English] Aha! See, I told you
I was gonna find a fish,
and you probably assumed
it was gonna be an alive one.
So technically, what I did there
is I catfished you.
[Moussa in French]
All of this is the vertebrae. The back.
-One, two, three, four, five, six, seven.
-[Nasser] Oh! Wow!
Almost seven vertebrae. It's a big fish.
[Nasser] Wow.
[Moussa] Fifty centimeters.
-[in English] Wow, that's really big.
-Yeah.
[Moussa in French] That's the head.
[in English] That's the head?
[Moussa in French] Yeah, that's the head.
The whole head.
Here are probably the fins.
And look, this is one piece.
And you have one here too.
It's complete.
-[in English] It's complete.
-[in French] Yeah, it's complete.
[Moussa] All of this
same fish.
-[Nasser] Same fish.
-Same fish, yeah.
[Nasser] Wow.
[in English]
So, we very carefully extract the remains
so Dr. Moussa can take the sample back
and study it.
[Moussa in French] There's a lot of wind.
-[Nasser in English] There you go.
-[Moussa] Okay.
[Moussa in French] We connect like this.
This is the head.
And the tail is over there.
-[Nasser] Wow!
-With the whiskers over here.
[in English] Oh, mustache right here.
[Moussa in French] Yes, exactly,
6,000 to 8,000 years old.
It swims like this.
[both laugh]
[Nasser in English] After we found the
fossilized fish in the dried-up lake
[laughs]
Dr. Moussa told me
that that fish wasn't swimming alone.
[in French] There are a lot of fossils.
Fish fossils sometimes.
And sometimes we find
hippopotamus fossils. [chuckles]
[Nasser] Wow!
[Moussa] And also crocodile fossils.
[Nasser in English] This whole place
is basically a giant pit of fossils,
but there's one kind
that's easy to overlook.
So, then what is this stuff?
What is this white stuff?
[in French] These are the diatoms
on the lake in question.
Diatoms are the algae
when they were green on the lake.
[in English] Oh! So, it's like the algae
on top of the lake.
[in French] Exactly.
And when it died,
it built up on the bottom of the lake
and became white.
It became a rock.
These are the skeletons
of the unicellular algae.
[Nasser in English] So then how does this,
which is pretty hard,
how does this become dust?
Diatoms are not hard at all.
You do this,
and you already have dust in your hand.
It's not hard. It's a soft rock.
Oh! Ha!
[in English] That's funny. It tastes
kind of like freeze-dried marshmallow.
[Moussa in French] Exactly.
[Nasser in English]
What if I told you that that fish
and, really, all the little critters
that lived in Lake Mega-Chad
thousands of years ago,
are having
an astonishingly weird afterlife?
So, it's so light
that it just gets picked up
and then it just goes?
[Moussa in French]
So, you have the Tibesti
and the Ennedi mountain range here,
so it creates a wind tunnel.
[Nasser in English] That wind grinds
those fossils down into a fine dust,
even finer than the sand all around it.
And then it kicks the dust into the air.
You can see, since we got here,
it's getting windier and windier.
The wind is just picking up
this fine white dust
and it's blowing it into the sky.
You can see
the sky is, like, basically white.
That's all the dust.
[in French] I thought that dust was going
here and was going to fall down,
and that's it.
But that's not the case.
Now we know this dust travels very far.
It goes on a long trip.
[in English] And from here it takes off
and who knows where it goes next?
Is it always this windy?
[Moussa in French] Yes.
[in English] Do you think it's better
for me to wear a turban?
Yeah.
-[in French] I will give you one after.
-Okay.
-Do you want to wear one?
-[in English] Okay, great.
[in French] That is not good enough.
[in English]
Yeah, it's not really working.
That fishy pixie dust can affect
everything from deadly hurricanes
to the nuts in your snack drawer,
to the oxygen we breathe.
So, let's follow that dust.
And to do that, we need to go to NASA
to meet dust specialist Chip Trepte.
So, take me from the dust's POV.
So, I'm the dust.
I'm sitting on the floor in the Sahara.
One day, there's a big storm.
A gust of wind just picks me up.
And then, what?
I can get lifted up,
way up in the atmosphere.
Say, four kilometers up high. Quite high.
It gets up there and now the winds
can carry it further to the west.
[Nasser] So, this Saharan dust
gets lifted into the sky,
leaves the African continent entirely,
and flies westward
toward the Atlantic Ocean.
There's so much of it
that astronauts in space
can see it with their naked eyes.
But only recently
have scientists been able
to actually study the dust from space.
With satellites, we can start, now,
to piece together that story.
How does it get lifted?
How does it move to the west?
And we now have
a much richer understanding
for how much of that dust
comes across as well.
[dramatic music playing]
[Nasser] It's like, to see
something so small
moving through our air,
you don't microscope in,
you telescope out.
Space telescope out.
[Trepte] This is the CALIPSO satellite.
It's in orbit. It flies over the poles.
And it flies every 90 minutes,
up at an altitude of 700 kilometers.
Oh, it loops the world every 90 minutes?
Every 90 minutes.
And it's been doing that since 2006.
That's when it got launched.
Regularly going on and on and on.
Onboard, it has a laser,
a laser that points down to the surface
and sends pulses of light
20 times a second.
Wait, 20 laser beams a second?
Mm-hm.
Lasers.
They're tracking dust, from space,
with lasers.
Of course they are.
So, it's like you're taking
a slice of the air.
Let's say the satellite
is going down here, and it's
bzzz, bzzz, bzzz, bzzz
It's, like, buzzing out
these lasers, right?
Twenty a second.
And so it's doing that super-fast,
and so each of these
is like a little report
from each of those laser blasts?
[Trepte] That's right. It fills them in.
I mean, it's hard to tell
if that's a lot of dust or a little dust.
Oh, we're talking a lot of dust.
This is around 50 million elephants
[Nasser] Of dust?
[Trepte] of dust, each year,
come off of the Saharan desert.
Wow.
Like, just looking at this is very trippy.
-[Trepte] It's stunning, isn't it?
-[Nasser] Yeah.
I feel like I'm on drugs. [laughs]
According to the data from CALIPSO,
the Sahara churns out
approximately 150 million tons of dust
every year.
That's basically the weight
of half the human population
a year.
So, my question is
"What happens to it?"
[lively music playing]
[pilot] Lead pressure looks good.
I'll give it a quick test of the count.
[man] We're chasing a storm
that's way out in the Atlantic,
so we're gonna start getting
some turbulence.
[Nasser]
Scientist Jason Dunion wants to know
what happens to the dust so bad
that he and his team
are flying directly
into the path of a hurricane to find out.
[beeping]
Lorenzo's a strong category-four storm
right now,
and we're coming in
from the southwest here,
so we're approaching
the edges of the storm.
Mother Nature has set up
kind of an interesting play
where we've got the Sahara Desert,
and just to the south is the nursery,
the breeding ground
for all of these hurricanes that we see.
[Nasser] Irma. Matthew. Maria. Ivan.
Over half of the Atlantic storms
big enough to get named
start as baby storms here,
off the West African coast.
The air pressure and warm water
create the perfect conditions
for brewing up a hurricane.
Will this hurricane, Lorenzo,
continue on its path of destruction?
Enter dust.
[Dunion] Here's a Saharan dust storm.
Where you see the yellows to reds,
that's telling us
there's dry, dusty air in the atmosphere.
If you were to pop
the United States on top of this,
you'd see basically a dust storm
that was the size of the lower 48 states.
[Nasser] The dust layer
is just north of the storm,
but the two are on a collision course,
and that's exactly the spot
where Jason wants to be
to see what happens.
There's so much dust,
it's definitely worth looking at,
because even a small effect
could have a huge effect
on the overall meteorology
we see out here in the tropical Atlantic.
[Nasser] When they get to the right spot,
cruising above the storm at 45,000 feet,
Jason and his team launch a device
out of the back of the plane
called a dropsonde.
[Dunion] So, these dropsondes
that we're launching out the plane,
they're like mini weather stations
with parachutes.
And it measures everything
we want to know about the atmosphere:
temperature, humidity, pressure, the wind.
It's an incredible amount of data.
It's really a real-time operation.
So, I'm watching this dropsonde
that we just put out.
It just penetrated the Saharan air layer
and it's falling right now
through the bottom.
So, the layer looks about
maybe a mile and a half
to two miles thick right now,
and it's got about half the moisture
that you'd see
in the moist tropical atmosphere.
[tense music playing]
[Nasser] Half the moisture,
which means the dust layer
is denying Lorenzo
the water it needs to sustain itself.
Not only that,
the dust is whipping through the air
at up to 50 miles per hour,
which means
it's basically putting tiny bullet holes
through those storm clouds.
[Dunion] It actually ran into
that Saharan air layer.
Looked like to be eroding
the western side of the storm,
so I'm probably going to expect to see
a slow decline
over the next 24 to 48 hours.
[Nasser] The dust layer is
basically smothering
a category-four hurricane
in the middle of the ocean.
This is a few of the reasons
why these Saharan dust storms
are really hurricane killers.
[Nasser] Now, obviously this doesn't
always happen,
but Jason and his team are convinced
that without the dust,
we'd get more severe hurricanes
making landfall every year.
[Dunion] I think as you get
more advanced with our science,
we realize the Earth
is really a connected place.
We've got the high-resolution dropsondes,
compared to what we can see from space.
That starts to give you
an appreciation of the big picture.
Things that are happening over Africa
don't just stay over Africa.
There are millions of tons of dust
that get exported across the Atlantic
every year,
along with this dry air
and the strong winds
and the warm temperatures.
It just doesn't stay there,
it actually affects the entire Atlantic.
[Nasser] But the dust that goes up
must come down.
Down to the ocean.
To study the dust that falls
in the middle of the Atlantic Ocean,
you actually have to be
in the middle of the Atlantic Ocean.
Well, not quite.
That would be way too far.
We're really just off the Dutch coast,
but just pretend.
[man] We know that there's a lot of dust
blowing over the ocean
from satellite images.
And most of this stuff
ends up in the ocean.
But no one has really sampled it
on the spot in the open ocean.
[Nasser] Jan-Berend Stuut is
a marine geologist
at the Royal Netherlands Institute
for Sea Research,
and he wants to know exactly what effect
the dust has on the ocean.
[Stuut] But the problem
with the dust falling onto the ocean
is that the ocean is very big.
If you want to go to the ocean
to sample this stuff, it's not so easy.
So that's why we had the idea
to monitor Saharan dust
across the Atlantic Ocean.
[Nasser] To make this easier,
he and his team anchored
three strategically placed buoys
across the ocean.
[Stuut] We have a few of these buoys
to collect material from the atmosphere,
and we also have instruments hanging,
suspended in the ocean,
that are collecting material
that's sinking down
and raining down towards the sea floor.
[uplifting music playing]
[Nasser] Jan-Berend's team goes out
to retrieve the samples once a year,
and today they're offering us
a little demo.
[Stuut] So, what we're looking at here
is the pride and joy of this project.
-[clatters]
-This is a dust collecting buoy.
[Nasser] The buoys stay
out there year-round,
constantly collecting dust,
like solar-powered
seaborne vacuum cleaners.
The dust gets sucked in
through a small chimney,
and you can even see some of the residue
from the last time this buoy
was out on the open ocean.
You can see there's a lot of dust
on the solar panels.
This is all Saharan dust.
[lively music playing]
We're gonna remove the solar panel
so that we can access this box,
where the filters are in there.
We're excited to see
how much dust is on the filters.
[Nasser] Jan-Berend takes
these dust samples
back to his lab in the Netherlands.
But he's less interested
in finding the dust
than finding out what it's actually doing
to the ocean.
[music stops]
[gentle music playing]
[Jan] The open ocean is really barren.
It's like a desert.
The plants in the ocean,
especially the open ocean
far away from land,
they need food.
And it turns out
that there's a lot of nutrients
in and on that dust,
from which plankton in the ocean
can profit.
So, they actually use it
as a nutrient source.
So, the dust from deserts
feeds the ocean deserts.
[Nasser] The Saharan dust
feeds these random, microscopic plants.
Okay, so what?
Well, those random plants
may be gulping down
tons of carbon dioxide in our atmosphere,
which in turn,
may be one of our best hopes
at curbing climate change.
[dramatic music playing]
[Stuut] So, we have to do something
to fight this increase in CO2,
and dust may be an instrument to do that.
The dust particles,
they tend to work as anchors
and drag down organic matter
to the sea floor.
If you manage to get that organic matter
to the sea floor,
you'll really have a net effect
on CO2 of the atmosphere.
[Nasser] The theory goes like this:
the dust drags that carbon
down to the seafloor like an anchor,
where it can't contribute
to the greenhouse effect.
It's a literal carbon sink.
[Stuut] So, it may seem
that the dust particles,
which are really tiny
and get blown across the ocean,
are unimportant, but I'm convinced
that they can play a big role
in the problems that we try to solve.
That's the big question
that's driving this research:
Can we stop the global warming
or at least reduce CO2 in the atmosphere?
[Nasser] Oh, and one other thing.
And here's where it gets
right up in your face.
Some of those dust-fed plankton
photosynthesize,
which means they're eating up sunlight
and burping out what makes life
for you and everyone you know possible:
oxygen.
[lively music playing]
Approximately half of the oxygen
in our atmosphere,
including the oxygen that we all breathe,
comes from ocean phytoplankton.
Half!
And scientists suspect a bunch of that
is thanks to the Saharan dust.
Dust plays a huge role in this cycle
of oxygen production and uptake of CO2.
[Nasser] And you can breathe easy.
Scientists estimate
that there's enough dust in the Sahara
to last at least another thousand years.
So, once it's in the water,
we say "Goodbye," and say "Good luck.
See you in another year.
Catch some dust for us."
[Nasser] At times, the dust seeds life,
but at other times,
the dust is a harbinger of death.
[dramatic music playing]
Some Saharan dust manages to cross
the entire Atlantic Ocean
and fall near the gulf coast of Florida
where Dale Griffin and his team
at the US Geological Survey
are waiting for it.
So, the amount of African dust
that falls out in Florida
is about two tons,
and iron content of African dust
is about five percent.
So that much iron alone
is coming from the Sahara
and setting down on Florida each year.
[Nasser] Dale is tracing
one devastating effect
of all that iron raining from the sky.
[Griffin] We have just started
doing experiments with Karenia brevis,
looking at the influence
of dust from different deserts
on how it will grow.
[Nasser] Karenia brevis is a microalgae,
and it triggers something biblically bad.
Right now, along more than a hundred miles
of the west coast of Florida,
it's killing fish
by the tens of thousands.
Dead. The whole bay is dead.
[Nasser] It's called "red tide."
A red tide can be red. It can be white.
It can be brown. There are mahogany tides.
[Nasser] Cynthia Heil heads
a research institute
devoted exclusively to studying red tide.
What we have here
are cultures of red tide,
basically red tide in a bottle.
There's literally hundreds of millions
of cells in here.
They're too small
to see the individual cells,
but when they get very, very concentrated,
you can see them at the surface here.
And it wouldn't be an issue,
except it's toxic.
[Nasser] It produces neurotoxins
that affect turtles, dolphins, manatees
[Cynthia] And we have fish kills
of literally hundreds of millions of fish.
[Nasser] But it doesn't just affect
marine life,
it affects us too.
When red tide hits the beach,
the sea spray
is full of those red tide toxins,
and people breathe them in.
And if you're healthy,
you feel like you're catching a cold.
We call it the "red tide tickle."
You get a tickle in your throat
and a stuffy nose,
and it's a little more difficult
to breathe.
If you have asthma or respiratory issues,
we advise to leave the beach immediately
because that can have
more serious impacts.
[Nasser] These red tide blooms
happen almost every year,
and they can be massive,
wreaking havoc on the ecosystem,
and doing millions of dollars in damage
to local economies.
[Griffin] Our main thing
is to develop an understanding
of how desert dust affects these blooms,
and is there some way
to contribute to minimizing the effects?
[Nasser] Who'd have thought
that a long-dead fish in a dried-up lake
could vault so high into the air
that astronauts could see it from space?
That it could fly across the Atlantic
and dry up the wettest
and wildest of hurricanes?
That it could seed plankton
that put oxygen in our air,
but also seed algae
that make it hard
for some of us to breathe it?
But we still haven't gotten
to the best part.
Every year, millions of tons
of Saharan dust finds its resting place
in the last place you'd ever expect.
A place that could not be
any more different
than the place it started.
That dust lands here,
thousands of miles from where it started,
in the Amazon rainforest.
[chuckles] Okay, so, you can't
actually see
the dust falling in the Amazon
with your naked eye.
According to scientists,
27 million tons of dust arrive here,
in the Amazon basin, every year.
That's the equivalent
of the Sydney Opera House
plus the Beijing National Stadium
plus the Burj Khalifa
plus the Great Pyramid of Giza
plus the Hoover Dam.
Now take all of those.
Double that
of dust
every year.
But in order to study it,
they have to catch it as it falls.
So, I'm going to go do that with them.
[percussion music playing]
I'm headed to a research station
deep in the Amazon.
It's around a six-hour trek
from the nearest city,
including a boat ride
along a tributary of the Amazon river.
I'm meeting a German researcher,
Stefan Wolff.
[Wolff] Hey, Latif.
-Very good to see you here.
-[Nasser] Hi.
-Give me your hand.
-[Nasser] Nice to meet you.
Nice to meet you.
Very welcome to the ATTO site.
[Nasser] Thank you so much. Wow.
What is your specialty?
What do you actually study here?
Actually, I'm a meteorologist,
and so, my scientific focus
is about how the forest
is interacting with the atmosphere.
[Nasser] As a meteorologist, you're here,
you're kind of looking up
Sometimes you don't even have to look up.
It looks like the clouds
are coming down to us.
But it sounds like
there's something else in the sky,
uh that's coming
all the way from Africa. [chuckles]
[Wolff]This is true. This is also
one very big part of our research.
So, the ecosystems
of very different regions of the Earth
are strongly interconnected.
Thousands of tons of Saharan dust sand
are brought regularly to the Amazon.
[bird chirping]
[Nasser] I'm kind of imagining
this cloud of dust and it just comes
and it's over the canopy
of the rainforest,
And then just
Can you paint a picture for me?
-[Stefan laughs]
-What happens?
Actually, it's like a very big
kind of invisible cloud for our eyes.
So, we have very sensitive instruments,
and they will make an analysis
of every particle,
and then we can detect,
"Okay, those particles were coming
from the Saharan desert."
[lively music playing]
[Nasser] After two planes, a bus, a boat,
a pickup truck, and a hike,
I finally made it.
So, what is this place? Where are we?
-We are at the ATTO site.
-ATTO.
ATTO. ATTO stands for
Amazon Tall Tower Observatory.
-[Wolff] Yeah.
-[Nasser] Oh. Wow.
Oh, my God. [laughs]
And he's not kidding
when he says "tall."
This thing reaches higher
than the Eiffel Tower.
[Wolff] This is the highest structure
we have in South America.
It's a tower
where we try to understand better
the Amazon basin.
It's about the whole system itself,
how it works, how it interacts,
and how it's very important
for the planet.
[Nasser] So, you made
a scientific skyscraper
-in the middle of the rainforest?
-[Wolff] Yes.
Yes.
There's an elevator, right?
[Wolff] The elevator's just not working.
Oh, God.
[energetic music playing]
So, guess where I'm going.
Up.
All right.
[Wolff] You see that this bunch of trees
is just kind of an area full of salad.
And then if you go higher up,
the salad is changed
into very big broccolis.
And then closer to the top of the tower,
these big spots of broccolis
are getting smaller and smaller.
And then you have
the whole green ocean below your feet
and seeing, "Wow. This is the Amazonian
ecosystem which you are seeing."
-The last steps.
-[Nasser grunts]
[groans]
Oh, my God.
-I can't feel my feet.
-Whoo!
[Nasser] Okay.
Three, two, one!
[laughs]
-You made it! [laughs]
-Oh, my God. [groans]
-Very, very great.
-Okay.
Oh, my God.
Oh, wow.
[Nasser laughs]
I'm at the top of this thing.
[tranquil music playing]
[Nasser] Wow!
[Wolff] Isn't it amazing to see
the Amazon basin here,
just in front of us?
So, the dust, it's coming over,
it gets swept up in Chad,
and then what happens here?
The dust is reaching
this Amazon basin,
and a big part of it
is just getting set down here
in the rainforest.
Thousands of tons will just settle down
and be picked up
by the upper canopy, by the middle canopy,
and even by the soil.
And this is acting like nutrition
for this ecosystem here.
The interesting point in the Amazon
is that the soil, basically,
in this region, is very unfertile.
[Nasser] Wait, what?
Yeah. The Amazon has a dirty secret:
the soil here sucks.
All the rain constantly washes away
nutrients, like phosphorus.
But guess what else contains phosphorus?
The corpses of the long-dead residents
of Lake Mega-Chad.
Every year, an estimated 22,000 tons
of Saharan phosphorus lands here,
almost exactly the amount
that the Amazon loses
to rain and flooding.
So, what falls from the sky
replenishes what gets washed away.
Without the dust, the Amazon may not have
what it needs to keep going.
So, it's keeping
this entire rainforest stable?
[Wolff] Exactly.
So basically, every one of those trees
should have been in contact with this dust
in the last years.
So, like every one of these trees
has a tiny bit of Sahara in them?
-Yeah.
-[Nasser] What?
That's nuts.
There are so many trees.
That's right,
our fishy friends from Lake Mega-Chad
have been fertilizing the Amazon
for at least a thousand years.
Without the world's driest,
most desolate place,
the world's most vital and vibrant place
wouldn't be what it is.
Out of death, life.
[in French] It's very important
and it's very beautiful.
All of this contributes.
They didn't die for nothing.
The dead diatom skeletons
and the fish skeletons contribute
to the life of another biodiversity.
So it didn't die.
That's the beauty of nature.
Like we say, "The dead are not dead."
So, the dead are alive somewhere.
[energetic music playing]
[Nasser in English] Alive in all kinds
of ways you'd never expect:
in a climate-change-fighting
plankton bloom,
in a family home
that didn't get hit by a hurricane,
in the trees of Brazil,
but also potentially
the nuts and berries they produce
that you eat every day.
Maybe even in the oxygen
in the breath you just took.
But there's one final thing
you should know.
The Bodélé Depression
isn't the only source of the world's dust.
Above our heads
is a planetary dust ballet.
Dust from Mongolia blows north over Canada
and lands on Arctic ice,
while dust from Patagonia
blows south onto Antarctic ice.
North African dust makes its way
to the Caribbean island of Guadeloupe
where it may trigger
more premature births.
And another branch of Saharan dust
goes north, past the Mediterranean,
and falls as snow in Central Europe.
So, if you're skiing in the Alps,
you're actually skiing
on top of the Saharan desert.
Scientists have yet to figure out
so many more of these dusty secrets,
but there's one thing we do know for sure:
wherever on this globe you take a breath,
you're breathing in somewhere else.
For better or worse,
we're all connected.
[energetic music playing]
[Nasser] Buckle up. I want to tell you
an epic story about life and death.
And the hero of this story is
the smallest of things.
It's everywhere,
but it's mostly invisible,
and it has secrets
that are even harder to see.
Secrets that connect space lasers,
a seaborne vacuum cleaner,
and the biggest bowl of salad on earth.
Secrets like how it defies death,
and how it's helping keep you
and virtually every living thing alive
right now.
To unlock all these secrets,
I need to travel to one of the most barren
and unforgiving places anywhere,
because that's the best place of all
to meet our unassuming hero.
This is a story about our dynamic
yet precarious planet,
where the littlest thing
can make the biggest difference.
-[music stops]
-[wind howling]
[upbeat music playing]
I'm Latif Nasser,
and this is a show about
the astonishing connections all around us,
connections between you and me
and our world
that'll make you see that world
in a whole new way.
[dramatic music playing]
This story begins
in the Central African nation of Chad.
So, it turns out
getting to the dustiest place
on planet Earth
is really, really difficult.
I've been traveling
for, like, three days now.
I flew into the capital city of Chad,
N'Djamena,
then from there
I flew into an oasis town in the north.
And from there, with Dr. Moussa here,
we're driving Whoa! [laughs]
We're driving a full day
straight into the Sahara Desert,
the hot, dry, bathroom-less Sahara Desert.
We are on our way
to a place called the Bodélé Depression
to look for a fish.
[energetic music playing]
We had to go with all of these soldiers
and paramedics
because if anything happened,
like if you get hurt,
there's nobody around to help you.
[wind blowing]
It's rare to go to a place
and be able to look in 360 degrees
and see nothing.
Like, this is the middle of the desert,
the middle of nowhere.
So, why am I on
a literal fishing expedition
in the Sahara Desert of all places?
Well, that fish is the starting point
to a global dust journey.
Ah!
Latif,
welcome in Bodélé.
-[Nasser] This is it?
-[Moussa] Yeah.
-[Nasser] Oh, wow.
-[Moussa] See!
Wow, it kind of just looks
like everything else.
[laughs]
[in French] It is the lake.
Everything you see in white,
-Yeah.
-it's the lake.
-[in English] Yeah. Oh, this is the lake?
-Yeah.
[dramatic music playing]
It's almost unimaginable now,
but that whole swath of desert
used to be underwater.
It was called Lake Mega-Chad.
At its peak, the lake was about the size
of modern-day Germany,
and it was as deep
as the Washington Monument is tall.
And it was full of fish
and teeming with life.
And then about a thousand years ago,
most of the lake abruptly dried up.
I cannot believe your job
is to look for fish in the Sahara Desert.
[Moussa in French]
Here when you look,
locals think you're looking for gold.
-Ah!
-I tell them, "No, it's not gold.
I'm a researcher."
But they don't believe me.
That's how it is.
We keep looking, looking, and looking.
[Nasser in English] What is
Is this like Is this a poop?
[Moussa in French] From a camel.
-[in English] Oh, that's camel poop.
-Yeah, camel.
Uh-huh.
-[Moussa in French] Let's keep looking.
-[Nasser] Mm-hm.
Dr. Moussa is one of the world experts
on Lake Mega-Chad.
What is that?
He's probably spent more time out here
than anyone.
I think it's a bullet.
Yeah, it's a bullet.
-In a gun?
-[Moussa] Yeah.
Oh my god. That's really big.
[Moussa in French] It's a 17 cartridge.
[imitates gun shooting]
People fight a bit.
Wow.
[Nasser in English] And then suddenly,
we find what we're actually looking for.
-[Nasser] Oh!
-Wow!
[Moussa in French] It's a beautiful piece!
[in English] What is it?
[in French] It's a catfish.
[in English] It's a catfish?
[in French] A catfish, yes.
[in English] Aha! See, I told you
I was gonna find a fish,
and you probably assumed
it was gonna be an alive one.
So technically, what I did there
is I catfished you.
[Moussa in French]
All of this is the vertebrae. The back.
-One, two, three, four, five, six, seven.
-[Nasser] Oh! Wow!
Almost seven vertebrae. It's a big fish.
[Nasser] Wow.
[Moussa] Fifty centimeters.
-[in English] Wow, that's really big.
-Yeah.
[Moussa in French] That's the head.
[in English] That's the head?
[Moussa in French] Yeah, that's the head.
The whole head.
Here are probably the fins.
And look, this is one piece.
And you have one here too.
It's complete.
-[in English] It's complete.
-[in French] Yeah, it's complete.
[Moussa] All of this
same fish.
-[Nasser] Same fish.
-Same fish, yeah.
[Nasser] Wow.
[in English]
So, we very carefully extract the remains
so Dr. Moussa can take the sample back
and study it.
[Moussa in French] There's a lot of wind.
-[Nasser in English] There you go.
-[Moussa] Okay.
[Moussa in French] We connect like this.
This is the head.
And the tail is over there.
-[Nasser] Wow!
-With the whiskers over here.
[in English] Oh, mustache right here.
[Moussa in French] Yes, exactly,
6,000 to 8,000 years old.
It swims like this.
[both laugh]
[Nasser in English] After we found the
fossilized fish in the dried-up lake
[laughs]
Dr. Moussa told me
that that fish wasn't swimming alone.
[in French] There are a lot of fossils.
Fish fossils sometimes.
And sometimes we find
hippopotamus fossils. [chuckles]
[Nasser] Wow!
[Moussa] And also crocodile fossils.
[Nasser in English] This whole place
is basically a giant pit of fossils,
but there's one kind
that's easy to overlook.
So, then what is this stuff?
What is this white stuff?
[in French] These are the diatoms
on the lake in question.
Diatoms are the algae
when they were green on the lake.
[in English] Oh! So, it's like the algae
on top of the lake.
[in French] Exactly.
And when it died,
it built up on the bottom of the lake
and became white.
It became a rock.
These are the skeletons
of the unicellular algae.
[Nasser in English] So then how does this,
which is pretty hard,
how does this become dust?
Diatoms are not hard at all.
You do this,
and you already have dust in your hand.
It's not hard. It's a soft rock.
Oh! Ha!
[in English] That's funny. It tastes
kind of like freeze-dried marshmallow.
[Moussa in French] Exactly.
[Nasser in English]
What if I told you that that fish
and, really, all the little critters
that lived in Lake Mega-Chad
thousands of years ago,
are having
an astonishingly weird afterlife?
So, it's so light
that it just gets picked up
and then it just goes?
[Moussa in French]
So, you have the Tibesti
and the Ennedi mountain range here,
so it creates a wind tunnel.
[Nasser in English] That wind grinds
those fossils down into a fine dust,
even finer than the sand all around it.
And then it kicks the dust into the air.
You can see, since we got here,
it's getting windier and windier.
The wind is just picking up
this fine white dust
and it's blowing it into the sky.
You can see
the sky is, like, basically white.
That's all the dust.
[in French] I thought that dust was going
here and was going to fall down,
and that's it.
But that's not the case.
Now we know this dust travels very far.
It goes on a long trip.
[in English] And from here it takes off
and who knows where it goes next?
Is it always this windy?
[Moussa in French] Yes.
[in English] Do you think it's better
for me to wear a turban?
Yeah.
-[in French] I will give you one after.
-Okay.
-Do you want to wear one?
-[in English] Okay, great.
[in French] That is not good enough.
[in English]
Yeah, it's not really working.
That fishy pixie dust can affect
everything from deadly hurricanes
to the nuts in your snack drawer,
to the oxygen we breathe.
So, let's follow that dust.
And to do that, we need to go to NASA
to meet dust specialist Chip Trepte.
So, take me from the dust's POV.
So, I'm the dust.
I'm sitting on the floor in the Sahara.
One day, there's a big storm.
A gust of wind just picks me up.
And then, what?
I can get lifted up,
way up in the atmosphere.
Say, four kilometers up high. Quite high.
It gets up there and now the winds
can carry it further to the west.
[Nasser] So, this Saharan dust
gets lifted into the sky,
leaves the African continent entirely,
and flies westward
toward the Atlantic Ocean.
There's so much of it
that astronauts in space
can see it with their naked eyes.
But only recently
have scientists been able
to actually study the dust from space.
With satellites, we can start, now,
to piece together that story.
How does it get lifted?
How does it move to the west?
And we now have
a much richer understanding
for how much of that dust
comes across as well.
[dramatic music playing]
[Nasser] It's like, to see
something so small
moving through our air,
you don't microscope in,
you telescope out.
Space telescope out.
[Trepte] This is the CALIPSO satellite.
It's in orbit. It flies over the poles.
And it flies every 90 minutes,
up at an altitude of 700 kilometers.
Oh, it loops the world every 90 minutes?
Every 90 minutes.
And it's been doing that since 2006.
That's when it got launched.
Regularly going on and on and on.
Onboard, it has a laser,
a laser that points down to the surface
and sends pulses of light
20 times a second.
Wait, 20 laser beams a second?
Mm-hm.
Lasers.
They're tracking dust, from space,
with lasers.
Of course they are.
So, it's like you're taking
a slice of the air.
Let's say the satellite
is going down here, and it's
bzzz, bzzz, bzzz, bzzz
It's, like, buzzing out
these lasers, right?
Twenty a second.
And so it's doing that super-fast,
and so each of these
is like a little report
from each of those laser blasts?
[Trepte] That's right. It fills them in.
I mean, it's hard to tell
if that's a lot of dust or a little dust.
Oh, we're talking a lot of dust.
This is around 50 million elephants
[Nasser] Of dust?
[Trepte] of dust, each year,
come off of the Saharan desert.
Wow.
Like, just looking at this is very trippy.
-[Trepte] It's stunning, isn't it?
-[Nasser] Yeah.
I feel like I'm on drugs. [laughs]
According to the data from CALIPSO,
the Sahara churns out
approximately 150 million tons of dust
every year.
That's basically the weight
of half the human population
a year.
So, my question is
"What happens to it?"
[lively music playing]
[pilot] Lead pressure looks good.
I'll give it a quick test of the count.
[man] We're chasing a storm
that's way out in the Atlantic,
so we're gonna start getting
some turbulence.
[Nasser]
Scientist Jason Dunion wants to know
what happens to the dust so bad
that he and his team
are flying directly
into the path of a hurricane to find out.
[beeping]
Lorenzo's a strong category-four storm
right now,
and we're coming in
from the southwest here,
so we're approaching
the edges of the storm.
Mother Nature has set up
kind of an interesting play
where we've got the Sahara Desert,
and just to the south is the nursery,
the breeding ground
for all of these hurricanes that we see.
[Nasser] Irma. Matthew. Maria. Ivan.
Over half of the Atlantic storms
big enough to get named
start as baby storms here,
off the West African coast.
The air pressure and warm water
create the perfect conditions
for brewing up a hurricane.
Will this hurricane, Lorenzo,
continue on its path of destruction?
Enter dust.
[Dunion] Here's a Saharan dust storm.
Where you see the yellows to reds,
that's telling us
there's dry, dusty air in the atmosphere.
If you were to pop
the United States on top of this,
you'd see basically a dust storm
that was the size of the lower 48 states.
[Nasser] The dust layer
is just north of the storm,
but the two are on a collision course,
and that's exactly the spot
where Jason wants to be
to see what happens.
There's so much dust,
it's definitely worth looking at,
because even a small effect
could have a huge effect
on the overall meteorology
we see out here in the tropical Atlantic.
[Nasser] When they get to the right spot,
cruising above the storm at 45,000 feet,
Jason and his team launch a device
out of the back of the plane
called a dropsonde.
[Dunion] So, these dropsondes
that we're launching out the plane,
they're like mini weather stations
with parachutes.
And it measures everything
we want to know about the atmosphere:
temperature, humidity, pressure, the wind.
It's an incredible amount of data.
It's really a real-time operation.
So, I'm watching this dropsonde
that we just put out.
It just penetrated the Saharan air layer
and it's falling right now
through the bottom.
So, the layer looks about
maybe a mile and a half
to two miles thick right now,
and it's got about half the moisture
that you'd see
in the moist tropical atmosphere.
[tense music playing]
[Nasser] Half the moisture,
which means the dust layer
is denying Lorenzo
the water it needs to sustain itself.
Not only that,
the dust is whipping through the air
at up to 50 miles per hour,
which means
it's basically putting tiny bullet holes
through those storm clouds.
[Dunion] It actually ran into
that Saharan air layer.
Looked like to be eroding
the western side of the storm,
so I'm probably going to expect to see
a slow decline
over the next 24 to 48 hours.
[Nasser] The dust layer is
basically smothering
a category-four hurricane
in the middle of the ocean.
This is a few of the reasons
why these Saharan dust storms
are really hurricane killers.
[Nasser] Now, obviously this doesn't
always happen,
but Jason and his team are convinced
that without the dust,
we'd get more severe hurricanes
making landfall every year.
[Dunion] I think as you get
more advanced with our science,
we realize the Earth
is really a connected place.
We've got the high-resolution dropsondes,
compared to what we can see from space.
That starts to give you
an appreciation of the big picture.
Things that are happening over Africa
don't just stay over Africa.
There are millions of tons of dust
that get exported across the Atlantic
every year,
along with this dry air
and the strong winds
and the warm temperatures.
It just doesn't stay there,
it actually affects the entire Atlantic.
[Nasser] But the dust that goes up
must come down.
Down to the ocean.
To study the dust that falls
in the middle of the Atlantic Ocean,
you actually have to be
in the middle of the Atlantic Ocean.
Well, not quite.
That would be way too far.
We're really just off the Dutch coast,
but just pretend.
[man] We know that there's a lot of dust
blowing over the ocean
from satellite images.
And most of this stuff
ends up in the ocean.
But no one has really sampled it
on the spot in the open ocean.
[Nasser] Jan-Berend Stuut is
a marine geologist
at the Royal Netherlands Institute
for Sea Research,
and he wants to know exactly what effect
the dust has on the ocean.
[Stuut] But the problem
with the dust falling onto the ocean
is that the ocean is very big.
If you want to go to the ocean
to sample this stuff, it's not so easy.
So that's why we had the idea
to monitor Saharan dust
across the Atlantic Ocean.
[Nasser] To make this easier,
he and his team anchored
three strategically placed buoys
across the ocean.
[Stuut] We have a few of these buoys
to collect material from the atmosphere,
and we also have instruments hanging,
suspended in the ocean,
that are collecting material
that's sinking down
and raining down towards the sea floor.
[uplifting music playing]
[Nasser] Jan-Berend's team goes out
to retrieve the samples once a year,
and today they're offering us
a little demo.
[Stuut] So, what we're looking at here
is the pride and joy of this project.
-[clatters]
-This is a dust collecting buoy.
[Nasser] The buoys stay
out there year-round,
constantly collecting dust,
like solar-powered
seaborne vacuum cleaners.
The dust gets sucked in
through a small chimney,
and you can even see some of the residue
from the last time this buoy
was out on the open ocean.
You can see there's a lot of dust
on the solar panels.
This is all Saharan dust.
[lively music playing]
We're gonna remove the solar panel
so that we can access this box,
where the filters are in there.
We're excited to see
how much dust is on the filters.
[Nasser] Jan-Berend takes
these dust samples
back to his lab in the Netherlands.
But he's less interested
in finding the dust
than finding out what it's actually doing
to the ocean.
[music stops]
[gentle music playing]
[Jan] The open ocean is really barren.
It's like a desert.
The plants in the ocean,
especially the open ocean
far away from land,
they need food.
And it turns out
that there's a lot of nutrients
in and on that dust,
from which plankton in the ocean
can profit.
So, they actually use it
as a nutrient source.
So, the dust from deserts
feeds the ocean deserts.
[Nasser] The Saharan dust
feeds these random, microscopic plants.
Okay, so what?
Well, those random plants
may be gulping down
tons of carbon dioxide in our atmosphere,
which in turn,
may be one of our best hopes
at curbing climate change.
[dramatic music playing]
[Stuut] So, we have to do something
to fight this increase in CO2,
and dust may be an instrument to do that.
The dust particles,
they tend to work as anchors
and drag down organic matter
to the sea floor.
If you manage to get that organic matter
to the sea floor,
you'll really have a net effect
on CO2 of the atmosphere.
[Nasser] The theory goes like this:
the dust drags that carbon
down to the seafloor like an anchor,
where it can't contribute
to the greenhouse effect.
It's a literal carbon sink.
[Stuut] So, it may seem
that the dust particles,
which are really tiny
and get blown across the ocean,
are unimportant, but I'm convinced
that they can play a big role
in the problems that we try to solve.
That's the big question
that's driving this research:
Can we stop the global warming
or at least reduce CO2 in the atmosphere?
[Nasser] Oh, and one other thing.
And here's where it gets
right up in your face.
Some of those dust-fed plankton
photosynthesize,
which means they're eating up sunlight
and burping out what makes life
for you and everyone you know possible:
oxygen.
[lively music playing]
Approximately half of the oxygen
in our atmosphere,
including the oxygen that we all breathe,
comes from ocean phytoplankton.
Half!
And scientists suspect a bunch of that
is thanks to the Saharan dust.
Dust plays a huge role in this cycle
of oxygen production and uptake of CO2.
[Nasser] And you can breathe easy.
Scientists estimate
that there's enough dust in the Sahara
to last at least another thousand years.
So, once it's in the water,
we say "Goodbye," and say "Good luck.
See you in another year.
Catch some dust for us."
[Nasser] At times, the dust seeds life,
but at other times,
the dust is a harbinger of death.
[dramatic music playing]
Some Saharan dust manages to cross
the entire Atlantic Ocean
and fall near the gulf coast of Florida
where Dale Griffin and his team
at the US Geological Survey
are waiting for it.
So, the amount of African dust
that falls out in Florida
is about two tons,
and iron content of African dust
is about five percent.
So that much iron alone
is coming from the Sahara
and setting down on Florida each year.
[Nasser] Dale is tracing
one devastating effect
of all that iron raining from the sky.
[Griffin] We have just started
doing experiments with Karenia brevis,
looking at the influence
of dust from different deserts
on how it will grow.
[Nasser] Karenia brevis is a microalgae,
and it triggers something biblically bad.
Right now, along more than a hundred miles
of the west coast of Florida,
it's killing fish
by the tens of thousands.
Dead. The whole bay is dead.
[Nasser] It's called "red tide."
A red tide can be red. It can be white.
It can be brown. There are mahogany tides.
[Nasser] Cynthia Heil heads
a research institute
devoted exclusively to studying red tide.
What we have here
are cultures of red tide,
basically red tide in a bottle.
There's literally hundreds of millions
of cells in here.
They're too small
to see the individual cells,
but when they get very, very concentrated,
you can see them at the surface here.
And it wouldn't be an issue,
except it's toxic.
[Nasser] It produces neurotoxins
that affect turtles, dolphins, manatees
[Cynthia] And we have fish kills
of literally hundreds of millions of fish.
[Nasser] But it doesn't just affect
marine life,
it affects us too.
When red tide hits the beach,
the sea spray
is full of those red tide toxins,
and people breathe them in.
And if you're healthy,
you feel like you're catching a cold.
We call it the "red tide tickle."
You get a tickle in your throat
and a stuffy nose,
and it's a little more difficult
to breathe.
If you have asthma or respiratory issues,
we advise to leave the beach immediately
because that can have
more serious impacts.
[Nasser] These red tide blooms
happen almost every year,
and they can be massive,
wreaking havoc on the ecosystem,
and doing millions of dollars in damage
to local economies.
[Griffin] Our main thing
is to develop an understanding
of how desert dust affects these blooms,
and is there some way
to contribute to minimizing the effects?
[Nasser] Who'd have thought
that a long-dead fish in a dried-up lake
could vault so high into the air
that astronauts could see it from space?
That it could fly across the Atlantic
and dry up the wettest
and wildest of hurricanes?
That it could seed plankton
that put oxygen in our air,
but also seed algae
that make it hard
for some of us to breathe it?
But we still haven't gotten
to the best part.
Every year, millions of tons
of Saharan dust finds its resting place
in the last place you'd ever expect.
A place that could not be
any more different
than the place it started.
That dust lands here,
thousands of miles from where it started,
in the Amazon rainforest.
[chuckles] Okay, so, you can't
actually see
the dust falling in the Amazon
with your naked eye.
According to scientists,
27 million tons of dust arrive here,
in the Amazon basin, every year.
That's the equivalent
of the Sydney Opera House
plus the Beijing National Stadium
plus the Burj Khalifa
plus the Great Pyramid of Giza
plus the Hoover Dam.
Now take all of those.
Double that
of dust
every year.
But in order to study it,
they have to catch it as it falls.
So, I'm going to go do that with them.
[percussion music playing]
I'm headed to a research station
deep in the Amazon.
It's around a six-hour trek
from the nearest city,
including a boat ride
along a tributary of the Amazon river.
I'm meeting a German researcher,
Stefan Wolff.
[Wolff] Hey, Latif.
-Very good to see you here.
-[Nasser] Hi.
-Give me your hand.
-[Nasser] Nice to meet you.
Nice to meet you.
Very welcome to the ATTO site.
[Nasser] Thank you so much. Wow.
What is your specialty?
What do you actually study here?
Actually, I'm a meteorologist,
and so, my scientific focus
is about how the forest
is interacting with the atmosphere.
[Nasser] As a meteorologist, you're here,
you're kind of looking up
Sometimes you don't even have to look up.
It looks like the clouds
are coming down to us.
But it sounds like
there's something else in the sky,
uh that's coming
all the way from Africa. [chuckles]
[Wolff]This is true. This is also
one very big part of our research.
So, the ecosystems
of very different regions of the Earth
are strongly interconnected.
Thousands of tons of Saharan dust sand
are brought regularly to the Amazon.
[bird chirping]
[Nasser] I'm kind of imagining
this cloud of dust and it just comes
and it's over the canopy
of the rainforest,
And then just
Can you paint a picture for me?
-[Stefan laughs]
-What happens?
Actually, it's like a very big
kind of invisible cloud for our eyes.
So, we have very sensitive instruments,
and they will make an analysis
of every particle,
and then we can detect,
"Okay, those particles were coming
from the Saharan desert."
[lively music playing]
[Nasser] After two planes, a bus, a boat,
a pickup truck, and a hike,
I finally made it.
So, what is this place? Where are we?
-We are at the ATTO site.
-ATTO.
ATTO. ATTO stands for
Amazon Tall Tower Observatory.
-[Wolff] Yeah.
-[Nasser] Oh. Wow.
Oh, my God. [laughs]
And he's not kidding
when he says "tall."
This thing reaches higher
than the Eiffel Tower.
[Wolff] This is the highest structure
we have in South America.
It's a tower
where we try to understand better
the Amazon basin.
It's about the whole system itself,
how it works, how it interacts,
and how it's very important
for the planet.
[Nasser] So, you made
a scientific skyscraper
-in the middle of the rainforest?
-[Wolff] Yes.
Yes.
There's an elevator, right?
[Wolff] The elevator's just not working.
Oh, God.
[energetic music playing]
So, guess where I'm going.
Up.
All right.
[Wolff] You see that this bunch of trees
is just kind of an area full of salad.
And then if you go higher up,
the salad is changed
into very big broccolis.
And then closer to the top of the tower,
these big spots of broccolis
are getting smaller and smaller.
And then you have
the whole green ocean below your feet
and seeing, "Wow. This is the Amazonian
ecosystem which you are seeing."
-The last steps.
-[Nasser grunts]
[groans]
Oh, my God.
-I can't feel my feet.
-Whoo!
[Nasser] Okay.
Three, two, one!
[laughs]
-You made it! [laughs]
-Oh, my God. [groans]
-Very, very great.
-Okay.
Oh, my God.
Oh, wow.
[Nasser laughs]
I'm at the top of this thing.
[tranquil music playing]
[Nasser] Wow!
[Wolff] Isn't it amazing to see
the Amazon basin here,
just in front of us?
So, the dust, it's coming over,
it gets swept up in Chad,
and then what happens here?
The dust is reaching
this Amazon basin,
and a big part of it
is just getting set down here
in the rainforest.
Thousands of tons will just settle down
and be picked up
by the upper canopy, by the middle canopy,
and even by the soil.
And this is acting like nutrition
for this ecosystem here.
The interesting point in the Amazon
is that the soil, basically,
in this region, is very unfertile.
[Nasser] Wait, what?
Yeah. The Amazon has a dirty secret:
the soil here sucks.
All the rain constantly washes away
nutrients, like phosphorus.
But guess what else contains phosphorus?
The corpses of the long-dead residents
of Lake Mega-Chad.
Every year, an estimated 22,000 tons
of Saharan phosphorus lands here,
almost exactly the amount
that the Amazon loses
to rain and flooding.
So, what falls from the sky
replenishes what gets washed away.
Without the dust, the Amazon may not have
what it needs to keep going.
So, it's keeping
this entire rainforest stable?
[Wolff] Exactly.
So basically, every one of those trees
should have been in contact with this dust
in the last years.
So, like every one of these trees
has a tiny bit of Sahara in them?
-Yeah.
-[Nasser] What?
That's nuts.
There are so many trees.
That's right,
our fishy friends from Lake Mega-Chad
have been fertilizing the Amazon
for at least a thousand years.
Without the world's driest,
most desolate place,
the world's most vital and vibrant place
wouldn't be what it is.
Out of death, life.
[in French] It's very important
and it's very beautiful.
All of this contributes.
They didn't die for nothing.
The dead diatom skeletons
and the fish skeletons contribute
to the life of another biodiversity.
So it didn't die.
That's the beauty of nature.
Like we say, "The dead are not dead."
So, the dead are alive somewhere.
[energetic music playing]
[Nasser in English] Alive in all kinds
of ways you'd never expect:
in a climate-change-fighting
plankton bloom,
in a family home
that didn't get hit by a hurricane,
in the trees of Brazil,
but also potentially
the nuts and berries they produce
that you eat every day.
Maybe even in the oxygen
in the breath you just took.
But there's one final thing
you should know.
The Bodélé Depression
isn't the only source of the world's dust.
Above our heads
is a planetary dust ballet.
Dust from Mongolia blows north over Canada
and lands on Arctic ice,
while dust from Patagonia
blows south onto Antarctic ice.
North African dust makes its way
to the Caribbean island of Guadeloupe
where it may trigger
more premature births.
And another branch of Saharan dust
goes north, past the Mediterranean,
and falls as snow in Central Europe.
So, if you're skiing in the Alps,
you're actually skiing
on top of the Saharan desert.
Scientists have yet to figure out
so many more of these dusty secrets,
but there's one thing we do know for sure:
wherever on this globe you take a breath,
you're breathing in somewhere else.
For better or worse,
we're all connected.