Nova (1974–…): Season 47, Episode 15 - Can We Cool the Planet? - full transcript

As global temperatures rise, scientists look to geoengineering solutions, from planting trees to sucking carbon out of the air, as a means to cool the planet.

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NARRATOR:Are rising temperatures driving

Earth's ecosystems past a point
of no return?

JANE LONG:
We can't go back.

There is no path backwards.

STEVE PACALA:
Every year, the damages
are worse.

NARRATOR:
We have promising technologies

that put solutions
within our grasp,

but are we reaching far enough?

FRANK KEUTSCH:
We have to have emissions

cut to zero.



Even if we stop emitting CO2,

we still have the CO2
we've already emitted.

NARRATOR:
So scientists are building
a new toolkit...

ATTICUS STOVALL:
It has power.

NARRATOR:
...to ensure
a prosperous future.

Our society has to survive.

SHEILA JASANOFF:
We need to reduce
the heating effect.

NARRATOR:
Cutting-edge solutions...

ALDO STEINFELD:It's going to be revolutionary.

LOLA FATOYINBO AGUEH:
It's like science fiction.

DAVID KEITH:
And there's the balloon
up there.

NARRATOR:
...and high-risk measures...

I really hope we'll never
have to do this.

It's really important that
humanity has a backstop.



NARRATOR:
...in a race to discover:

can we cool the planet?

Right now, on "NOVA."



ANNOUNCER:
Major funding for "NOVA"
is provided by the following:

JASANOFF:
It's a new time
in the Earth's history

in which we are not just
inhabiting our planet,

we're operating as stewards
of the very thing

that we're living on.

NARRATOR:Since the Industrial Revolution,
humanity has been running

an unintentional experiment

in Earth's atmosphere,

pushing the climate
to new extremes.

LONG:
Things are going to get hot.

MAN:
Boy, you can feel the heat.

This is insane!

Oh, my God.

PACALA:
Attitudes have changed rapidly

because everyone can see
for themselves

the climate change
that is occurring.

NARRATOR:A child born today will witness,
across her lifetime,

a planet transformed
by rising temperature.

MAN:
I got you, I got you.

NARRATOR:
How did we get here?



LONG:Every time you get in your car,

every time you fly a plane,

every time you turn the heat on,

all of those things
are putting carbon dioxide

into the atmosphere,

and if there's more carbon
dioxide in the atmosphere,

there's a higher temperature.

NARRATOR:
And now temperatures
have started to spike.

KEITH:
If we keep pumping billions
of tons of CO2

into the atmosphere each year,

we really will cook ourselves,
literally, in the end.

(birds squawking)

NARRATOR:
To stop the worst impacts

of planetary heating,
we need rapid emissions cuts,

starting now.

PACALA:
The developed nations
of the world

need to go fromthe energy system they have now

to one that emits nothing, zero,
in 30 years' time.



The good news is, we know
how to do that.

Renewables now are the cheapest
form of electricity

on two-thirds
of the Earth's surface,

and it's going to be everywhere.

NARRATOR:
A world of carbon-free energy
is coming.

(thunder crackling)

But climate impacts
are coming faster.

KATE MURPHY:
Lasers are at power.

There it is.

NARRATOR:
So scientists are openinga second front in the battle...

STOVALL:
Sweet. It has power.

NARRATOR:
Bringing new technologies

to bear on the way we fight
climate change...

FATOYINBO AGUEH:
We now have so much data.

This is going to be
a game-changer.

PACALA:
There are a whole class
of solutions

to actually get this job
all the way done.

NARRATOR:By removing CO2 from the air...

SANDRA SNAEBJORNSDOTTIR:
This little guy,

this is just the beginning.

NARRATOR:
Converting CO2 from a waste

to a resource...

APOORV SINHA:
We see this kind of
as a testing ground.

NARRATOR:
Even extreme measures,

like shielding us from the sun.

(machinery whirring)

PACALA:
There's been a technical
revolution

in the last few years

that's unlike anything
we've seen

in the previous hundred.

This is a problem
with a solution.

NARRATOR:
Can a new wave of climate tech
take us the rest of the way

to turn down
the global thermostat?

KEUTSCH:
We need to look at everything
that's out there--

natural solutions,

CO2 sequestration,

solar geoengineering.

There may be this idea out therethat nobody has come up with yet

that could be really
transformative.



NARRATOR:Cooling the planet means, first,
stopping more CO2

from entering the atmosphere

and then finding ways
to remove it.

But just how much CO2
are we talking about?

Imagine you filled
the National Mall all the way

from the Lincoln Memorial to the
Capitol steps with coal...



...and you piled it up
all the way

to the top of the
Washington Monument ten times.

That would be a gigaton of coal.

"Giga" means billion,
so that's a billion tons.

Now, we actually burn ten times
that much carbon every year.

People actually go dig that
stuff up out of the ground,

ten billion tons of it,

and set it on fire
in power plants, in engines,

in factories all over the world.

(imitating combustion)



And then because that carbon has
reacted with oxygen,

ten gigatons of carbon
is burned,

but it creates 37 gigatons
of CO2.

NARRATOR:At our current rate, that's just
one year of CO2 emissions.



To blunt the impacts
of heating the planet,

we need to shrink that number,

to zero.



But there's another problem--

the gigatons that came before.

LONG:
The single most important fact
about climate change

is that the carbon dioxidethat we emit into the atmosphere

stays there
for thousands of years.

NARRATOR:
Year after year, we live with
the carbon dioxide

we've added over time--
nearly 1,000 metric gigatons

since the Industrial Revolution
began.

LONG:
Almost everything we emit
stays there,

and it's staying there

until you do something about
taking it out.



NARRATOR:
Pulling CO2 out of the air.

(men speaking on radios)

NARRATOR:
It sounds futuristic,

but it's a problem
we've encountered before.

JAN WURZBACHER:
Remember Apollo 13?

It was all about CO2 filtering,
right?

That was the big problem, how to
get the CO2 out of the air.

(indistinct radio chatter)

NARRATOR:In 1970, following an accident,

the crew of Apollo 13 aborted a
mission to land on the moon.

JOHN SWIGERT (archival):
Houston, we've had a problem.

NARRATOR:
Forced to return to Earth
in a smaller capsule,

the astronauts faced
a big problem.

WURZBACHER:
You're in confined spaces.

People exhale CO2.

You need to remove that CO2.

(person exhales)

NARRATOR:
Every exhale caused
carbon dioxide to build up,

making the air
increasingly toxic.

MAN (archival):
Okay, now, let's everybody
keep cool.

Let's solve the problem

but let's not make it any worse
by guessing.



NARRATOR:
The astronauts survivedby modifying their air scrubber

to remove more carbon dioxide.

(air flowing)

Inside the scrubber,
negatively charged sites

on the filter polarize and bond
with the CO2,

removing it from the air.

Could something like this work
in Earth's atmosphere?

DENNING:
There's not a lot of CO2
in the air compared to

nitrogen and oxygen.

Imagine a box with 10,000
ping pong balls in it

and four of them
are painted black--

those are the CO2 molecules.

Trying to find those four balls
out of that big box

full of ping pong balls is hard!



NARRATOR:
Removing CO2 from a spacecraft
is one thing.

Removing it from our atmosphere
poses a much bigger challenge.



Is it realistic?

WURZBACHER:
Most people to whom we told
we are taking CO2

out of the air would say,
"You're crazy."

But here you see a full-scale
direct air capture plant.

You see it consists of
12 individual modules

capturing the CO2
out of the air.



NARRATOR:
Jan Wurzbacher is a co-founder

of Climeworks,
a Swiss start-up specializing

in what's called
direct air capture.

Through this side, we suck in
ambient air with 400 PPM--

that's 400 parts per million
CO2.



And on the other side, we expel
about 100 PPM CO2 content.

So three-quarters
are kept inside.

NARRATOR:
A filter with highly reactive
chemicals called amines

catches even small
concentrations of CO2.

Heating the filter
then breaks the bond.

WURZBACHER:You release the CO2 and you can
extract pure concentrated CO2.

And then you start
all over again.



NARRATOR:But generating the energy to do
this can produce its own CO2.



Their solution for that

is garbage.

Here we are on top of
the waste incineration plant.

The reason why we're here is
the main energy source

for our process of CO2 capture
from the air,

waste heat from the
incineration process.

NARRATOR:Heat that would have been wasted
instead heats the filters

inside the array,

which capture nearly 1,500metric tons of pure CO2 a year--

about what's expelledfrom the tailpipes of 300 cars.

PACALA:
Once you've pulled

CO2 out of the atmosphere with
a direct air capture machine,

the question is what to do
with it.

WURZBACHER:
The big picture is taking

one percent of CO2 out of the
atmosphere

within the next
five to ten years--

that is roughly 400 milliontons-- and store it underground.



NARRATOR:
Could we put carbon right back
where we found it--

underground?

PACALA:
There are lots of rocks
near the surface of the Earth

that would want to bond
spontaneously with CO2.

There's enough of thesekinds of minerals that you could

remove all of the atmospheric
CO2 many, many times over.



NARRATOR:
One of the best places to try
that out is Iceland.



SNAEBJORNSDOTTIR:
Here we are--

the land of ice and fire.
(laughs)

We have eruptions.

We have earthquakes.

NARRATOR:Iceland is an island formed outof volcanic rock called basalt.

We see the basaltic mountains
here around me

and actually extending
several kilometers downwards.

NARRATOR:
Basalt is porous rock
that readily bonds with CO2

over centuries.

Sandra Snaebjornsdottir's team
has found a way

to speed up that process.

SNAEBJORNSDOTTIR:
CarbFix is the method

of capturing CO2
and turning it into stone.

It's magic, but it's magic that
already occurs in nature.

NARRATOR:CarbFix is turning one-third of
the CO2 from this power plant

into solid rock
in less than two years.

The key is water.

Inside this scrubber, gaseous
CO2 is dissolved in water

to react with basalt
more quickly.

SNAEBJORNSDOTTIR:
This scrubber is actually

just a giant SodaStream.

NARRATOR:
The fizzy water is then pumped
into injection wells.

SNAEBJORNSDOTTIR:
This is actually my favorite
part of it all.

From here, the magic
starts to happen.

This pipe extends
to over 2,000 feet.

And there, we finally release
this fluid to the rock.



NARRATOR:
Once inside the basalt, thedissolved CO2 reacts with metals

in the rock to form new solidminerals like calcium carbonate.

Once we have injected the CO2
into the rock,

it's there forever.

NARRATOR:
And Sandra is looking
beyond Iceland.

She is test-driving

a direct air capture unit
that can suck up CO2 anywhere.

SNAEBJORNSDOTTIR:
We don't need the power plant.

This can be done

anywhere where you have
a formation to store your CO2.



LONG:
What that means is,
you can go backwards.



You can reverse the process

of emitting carbon dioxide
into the air.

NARRATOR:Negative emissions technologies
like direct air capture

could play a role
in reaching net zero,

the moment when humans removeas much CO2 from the atmosphere

as they put in.

So why isn't this the ultimate
answer to our CO2 problem?

LONG:
These technologies are

very hard to scale up
to a meaningful amount.



WURZBACHER:
The base module of our direct
air capture plant,

that's a 40-foot
shipping container.

In order to take one percent ofglobal emissions out of the air,

we would need 750,000
shipping containers.

NARRATOR:
All to remove just half agigaton of our annual emissions.



DENNING:
Direct air capture
is very expensive

and it takes energy to suck CO2
out of the air.

So I hope you're not imagining

direct air capture vacuuming upthe entire fossil fuel emissions

of the world, because it ain't
gonna happen.

NARRATOR:
We'll need lower-cost clean
energy everywhere

before the promise
of direct air capture can meet

the scale of the problem.

(switch clicks)

M7 is on.

NARRATOR:
So some are exploring another
idea: recycling our emissions.

MAN:
Correction factor 0.7.

LONG:
We need to think about this
problem very pragmatically.

We can electrify
a lot of things.

But there are certain parts
of the energy system

that are extremely hard
to decarbonize.



PACALA:
A good example is aviation.

WURZBACHER:
You couldn't build today
a commercial airplane

for long distances
which could fly on batteries.

You would just carry way
too much weight.

STEINFELD:
This is physically impossible.

There is no way around jet fuel.



LONG:
We need to be producing fuel
that, when you burn that fuel,

it doesn't emit carbon dioxide.

Remo, go ahead and rotate.

NARRATOR:
Aldo Steinfeld thinks
he's found a way.



STEINFELD:
Perfect. We are on target.

We have demonstrated that we canproduce liquid hydrocarbon fuels

from two ingredients.

Sunlight

and ambient air.



(whirring)

It may sound like
science fiction or magic...

(whirring)

But it is chemistry,

it is heat transfer,

and also, it's a lot
of engineering.



NARRATOR:
Aldo captures CO2 and water
from the air

and feeds them into
a solar reactor.

STEINFELD:
Solar radiation is reflected

and concentrated at the focus
by a factor of 5,000.

It is like the intensity
of 5,000 suns.

NARRATOR:
Concentrated solar energy

drives a reaction that generates
a synthetic gas,

which can then be
converted into fuels.

And here in my hands,
I have an example of

solar methanol.



NARRATOR:
When it's burned,

the carbon in this fuel
returns to the atmosphere.

But since it was harvested
there, the net CO2 is zero.

This is called carbon-neutral,

and hundreds of scientists
like Aldo are working to make

carbon-neutral fuels a reality.

If they succeed,annual net emissions would drop

by as much as one billion tons.

It's going to be something
revolutionary.

NARRATOR:
But with these fuels up to sixtimes the cost of standard fuel,

it's a revolution
that has only just begun.

But it raises the question:

what else can we make
by recycling CO2?

DENNING:
Carbon is this incredible
building block.

Think of it like

those little sort of Lego toys
that we used to have,

only there's four little
plug-ins for it.

So you could bond carbon
to carbon to carbon to carbon

to build all kinds of stuff.

MAN:
Imagine a world
where everything around you

is made from carbon emissions,

from the products you use
everyday

to the clothes you wear.

NARRATOR:
This ad from the
XPrize Foundation pitches

a future where recycled CO2
shapes our world--

and a $20 million bounty
to make that a reality.

We announced, "Hey, there's
a $20 million prize out there,

"we're looking for innovators
around the world.

"If you know how to convert CO2
into a useful material,

consider entering this prize."



We are trying to help catalyze
the whole ecosystem

of companies, of investors,

of people that can deploy these
technologies.



NARRATOR:
The Carbon XPrize has brought
five of the finalists here

to put their innovations
to the test.

They're setting up shop next to
a plentiful supply of CO2.

EXTAVOUR:
They've got to take
the emissions

from a natural gas power plant

and convert those into whatever
material they like.

NARRATOR:
From toothpaste...

to yoga mats...

to watches.

Each team will be scored
on its net CO2 reduction.

EXTAVOUR:
You could have a process

that uses up a lot of CO2to make its product,

but in the end, just produces
more CO2 than it uses up.

Okay.

We don't want that.
Yup.

We want things that actually
are reducing CO2 overall.



SINHA:
We just moved to site
about two weeks ago.

A day later,
and I think we'd have

(chuckling):
snow in here that we'd be
shoveling out, so...

NARRATOR:
Apoorv Sinha is the C.E.O. of
Carbon Upcycling Technologies,

or CUT.

We're a carbon tech company
which takes carbon emissions

and converts them into solid
nanomaterial products

for use in anything from cutlery
to car parts.



NARRATOR:
But to make the biggest impacton CO2 and win this competition,

Apoorv is focused on cement.

Cement is an essential component
of concrete--

the glue that binds
it together.

But producing it creates
a lot of CO2.

SINHA:
Cement production accounts

for over eight percent of the
world's annual emissions.

If all the cement-producing
companies were a country,

they would be the third-largest
emitter in the world.



NARRATOR:
Apoorv's process converts CO2

into a needed ingredient
for concrete.

And he believes it will also

reduce the amount of cement that
concrete manufacturers need.

He starts with an industrial
waste powder

left over from burning coal

called fly ash.

With the reactor
that we have behind us,

we're scaling up
and commercializing

an enhanced fly ash,
where the fly ash has been

chemically activated
to capture CO2.

As the reactor spins
the fly ash, we inject CO2.

Ball bearings coated
with a catalyst

speed up the chemical reaction.

As the ball bearings
rise and fall,

the motion breaks up
the fly ash

and roughs up the surface, so
that more CO2 can be absorbed.

NARRATOR:
As the CO2 penetrates
the fly ash surface,

it forges tunnels along the way.

In effect, carbondioxide has bonded with fly ash

to create a nanoparticlewith more reactive surface area,

which can bind
concrete together

and strengthen it
with less cement.

SINHA:
If concrete producers
are able to use less cement

in their production, they could
considerably reduce

the emissions that come
from their industry.

NARRATOR:
The question remains:

is it strong enough
for concrete makers to buy it?

We just want to make sure
that the technology is good,

and that it works really well.

SINHA:
One of our local partnersis a family-owned Calgary-based

concrete business called Burnco.

NARRATOR:
Burnco is testing the strength
of concrete held together

using Apoorv's nanoparticle.



MAN:When the cylinder breaks,

we will have our final pressure
read up there.



NORM KUNTZ:
These are impressive results.

In normal production,
you're looking for changes

of three to four percent,
and these are showing

results in, in double digits,

which is very encouraging.



SINHA:
We're very confident
that we can get

up to a ten percent reduction

in the amount of cement
used today.

But our real target is to get
that number up to 20% or 25%.



Then we start talking aboutsignificantly moving the needle

on the 37-gigaton-a-year number.

NARRATOR:
But even if these new
technologies can scale

to their full potential,

they could only lock away
a fraction of our emissions.

KEITH:
The total volume of CO2that we create in the atmosphere

is so much biggerthan the volume of any product.

I think people are losing track
of the central issue,

which is, we have to reduce
net CO2 emissions.

DENNING:
The easiest thing,

believe it or not,
is to burn less carbon, right?

To, to not generate the CO2
in the first place.

NARRATOR:
Carbon-free energy like wind,
solar, and nuclear power

can drive down most of our
annual emissions.

And the rest could be offset

with negative-emissions
technologies

that remove CO2 from the air.

KEITH:
We will do it.

We will get to the day--there'll be global celebrations

when we get to net zero day,

where we brought human CO2
emissions to zero.

I think it'll happen
in my lifetime.

It is doable.

But on that day,

we have not solved
the climate problem.

All we've done
is stop making it worse.



NARRATOR:
The problem that remains
is heat.



DENNING:
The temperature of the Earthis determined by heat coming in

from the sun

and heat going out
by radiation out to space.



NARRATOR:
Every single day,
CO2 from our past emissions

traps energy
in the Earth's system--

the same amount of energy
as 500,000 of the bomb

dropped on Hiroshima
detonating at once.

That heat is altering
our climate.

What's it going to be like when,
you know,

three months of the year
are 115 degrees?

When vast ecosystems have
died out?

People are going to push for,for doing something about this.

NARRATOR:
And many fear Earth is
approaching a tipping point

that will trigger rapid change.

PACALA:
The uncertainties that keep me
up at night are,

what if we aren't doing enough,

and there's some monster lurking
behind the door

that all of a sudden comes

out into the world
among us?



It's a good idea that humanity

has some sort of
a backstop technology,

something to do if we get
surprised in a way

that is very, very dangerous.

NARRATOR:
Some think that backstop could
be solar geoengineering.

PACALA:It's a way to intercept sunlight
coming into the planet

to cool the planet.

KEITH:
The core idea is that humans
might deliberately alter

the Earth's energy balance to
compensate for

some of the warming and
climate changes

that come from greenhouse gases.



NARRATOR:Geoengineering the climate is a
controversial idea.

But nature can show us examples
of where we might start--

clouds.

SARAH DOHERTY:
A cloud is just water that's
condensed down onto particles

into small droplets.

NARRATOR:
These collections of droplets
are, in effect,

floating sun reflectors.

Clouds play a huge role in
controlling the climate

because they control the
reflectivity of the planet.

Especially over the ocean,

you go from sunlight hitting a
very dark surface,

where a lot of the sunlight
is absorbed,

to sunlight hitting an
extremely bright surface,

reflecting a lot of that
sunlight back to space.

NARRATOR:
Sarah Doherty of theMarine Cloud Brightening Project

is working on a way to boost
that effect.

DOHERTY:Can we add really small sea salt
particles to clouds

in a way that significantly
increases their brightness,

and do so over enough of
the ocean that we would have

a significant impact
on the global temperature?

NARRATOR:
But how do you make saltwater
particles

and launch them up into clouds?

DOHERTY:
What we need is a nozzle

like you'd see in a sort of a
snowblower,

except that the particles that
we want to produce are about

a thousandth the width of
a human hair.

(humming)

NARRATOR:
So Sarah's working with
an engineer

who knows all about machines

for spraying
super-fine droplets--

a concept developer of
the earliest inkjet printers.

ARMAND NEUKERMANS:
In a different life, I was an
engineer and a physicist.

I couldn't enjoy retirement
anymore and just sit there

and watch what's going on.

Once you know what's going to
happen or might happen,

you can't sit down and say,

"Yeah, I'm just going to enjoy
life."

NARRATOR:
Armand and his team of
retired scientists

have been developing a
cloud-brightening machine

for over ten years.

MURPHY:They have been self-funding thisresearch in borrowed lab space.

PARC is a really good place
for them

because of our history
with aerosols.

NARRATOR:
PARC, or Palo Alto
Research Center,

has infused the Marine Cloud
Brightening Project

with fresh expertise and
cutting-edge tools.

Here, Kate Murphy can make
aerosols

from just about anything.

This is our deep conditioner.

NARRATOR:
Aerosols are tiny particles
suspended in air.

This is ketchup.

(machine whirring)

NARRATOR:For clouds, they're not going to
spray ketchup.

But Kate can help the team

design a nozzle for spraying
saltwater.

Let me just give it a little
water, okay?

MURPHY:
Okay.

NARRATOR:
Kate's expertise will
help optimize

the size and speed of
the particles

to propel them into
marine clouds.

SUDHANSHU JAIN:
So you're going to be
redesigning the nozzle

based on your computational
fluid dynamics?

Well, we hope to be able to
understand the effect

of multiple nozzles,

so we would want to measure
things

like velocity and direction.

NARRATOR:
These crisscrossed laser beams
can help reveal

whether Armand's nozzle will
hit the mark.

MURPHY:
The lasers are at power.

Um, it looks like our signal's
pretty good.

NEUKERMANS:So can you measure thevertical velocity?

Do you have a measurementof that?
Yes.

That would beof great interest to us.

DOHERTY:
PARC will be working ondeveloping a full spray system.

And then we would want
to move outside,

into real atmospheric
conditions.

NARRATOR:On the other side of the world,

outdoor research has
already begun.



Armand and the team have shared

their insights with researchers
in Australia

who are testing cloud
brightening as a way to cool

the waters surrounding the
threatened coral of the reef.



That project is targeted
and local,

but some estimate that cloud
brightening on a global scale

could offset all the heat
trapped by our CO2 emissions.

DOHERTY:
It will probably take
a good 15 to 20 years

to do all of the research
involved with understanding

how big of an effect we can have
by brightening clouds

and also what all of
the side effects might be.

NARRATOR:
Those side effects are not
well understood,

and could include disruptions

to ecosystems
and rainfall patterns.

Further research is needed.

We have kids,
we have grandkids...

We're doing it
for their futures.

NEUKERMANS:You know, and frankly,

we are all in this together,whether you have kids or not.

NEUKERMANS:
We're more than individuals.

Our society has to survive.



NARRATOR:
We're facing a problem that's
getting worse, not better.

Do we need to consider
more extreme measures?

KEUTSCH:
In 15 years or 20 years,

humanity may find itself
at a point

where impacts are so big that

there's a very large demand
for fast action.

NARRATOR:
To prepare, Frank Keutsch
is starting now,

by researching
a controversial technology

that goes further
than brightening clouds.

It would brighten
the entire planet.

KEUTSCH:
Putting particles
in the stratosphere

could reflect back
some sunlight to space,

reducing the amount of sunlight
that hits the surface

and cooling down the planet.

NARRATOR:
The effect would be immediate.

(volcano erupting)

PACALA:
We know this works,

because every time
a big volcano goes off

and it injects aerosols
into the stratosphere,

the planet cools down.

JASANOFF:
That's the idea behind
solar geoengineering.

It's like drawing a curtain over
the face of the Earth.

KEUTSCH:
The first time
you hear about this,

you think, well, "That sounds
like a really bad idea.

How could that not go wrong?"

But what we're doing
to climate as humans,

that really to me starts
seeming also quite scary,

and crazy, and really worrying.

The fact is, the CO2 is
in the atmosphere.

Without a time machine,
we can't make it go away.

We want to, in the long run,
do carbon removal.

But during the time
that concentrations are high,

we might want to
do solar geoengineering

to reduce the climate risk.



KEITH:All that is hard-mounted to us.

(group agreeing)

That is exactly
what I was...

And then there's
the balloon up there.

NARRATOR:
Frank and David's team
is designing

a first-of-its-kind experiment,

called SCoPEx,

to investigate the impacts of
solar geoengineering.

The only place I see that
conversation getting sticky

is where we do
risk assessment on it.

KEUTSCH:If you put these particles out,

what happens
when these come back down?

What happens when
it gets into the environment?

Are we endangering people?

KEITH:
There are lots of things
that we might need to know

where the existingexperimental background is bad.

You actually have to go out
and make measurements.



NARRATOR:
The plan is to launch

a 100-foot balloon
into the stratosphere

and releasea plume of reflective aerosols.

KEUTSCH:
We want to put out

the particles ofcalcium carbonate, for example,

and then go back
through this plume

and see whether
the evolution of the air

is the way we predictedbased on our laboratory results.

This is an experiment
on a very small scale.

And in fact,

the amount of material
we're putting out

is less than a normal
airplane flight puts out.

NARRATOR:
SCoPEx may be small,

but many fear
a large-scale manipulation

of Earth's atmosphere
could trigger

a cascade of dangerous,

unintended consequences
that ripple across the planet.

JASANOFF:
Nothing in our
scientific capability

actually enables us
to understand the complexity

of the interactions
that would be set loose.

It's not just that
it lowers the temperature,

but what are some of
the other effects

on the hydrologic cycle,

or on heat waves and droughts?

JASANOFF:
This is a manipulation of
the Earth's atmosphere

on a huge scale.

What happens if things go wrong?

NARRATOR:
SCoPEx is designed to

start answering those questions.

But there may be effects,
beyond the physical,

that no experiment can predict.

JASANOFF:
If we think that there's
this solution out there,

then people may think

it doesn't matter if
you're polluting the planet.

KEITH:
The root of the concern

is that solar geoengineering
research,

however well-intentioned,
will be used as an excuse

for big fossil fuels
to fight emissions cuts.

DENNING:
It's just like a sci-fi
dystopian novel or something,

where we continue to just

belch all this CO2
into the atmosphere,

but hey, it's okay, because
we got these little umbrellas

that are, you know,
hiding us from the sun.

KEITH:
Solar geoengineering does not
get us

out of the ethical and physical

requirement to cut emissions.

NARRATOR:
But with so much uncertainty,

some think we're better off

investing in
a different kind of machine:

one developed in
nature's own laboratory

over millions of years,
and with a proven record

of safely drawing down
gigatons of CO2.

Trees.

(birds chirping)

FATOYINBO AGUEH:
When I'm going on a hike
through a forest,

I have a tendency
to look up and say,

"Okay, oh, that tree's about
60 feet tall."

And then I try to calculate
in my head, okay,

how much carbon is stored
in that tree?

I think this is good.

NARRATOR:
Lola Fatoyinbo Agueh

is a research scientist

at NASA's
Goddard Space Flight Center.

Sweet. It has power.

I love it when things work.

NARRATOR:
She and her team
are about to see

these century-old trees in
a new light.

STOVALL:Green lights all around, if you
want to do the honors.

FATOYINBO AGUEH:
There's carbon all around us.

If you think of trees
as a machine,

then trees would be
a carbon capture machine.

When we're looking at trees,

about half of that weight
is carbon.

NARRATOR:
Lola and her team want to know

how much carbon is stored
in this entire forest.

To measure each and every tree,

they're using a
special kind of tool...

Lasers.

FATOYINBO AGUEH:
We're using a terrestrial
laser scanner

that shoots out billions of
laser pulses every second

and then measuresthe distance from the instrument

to whatever is around it.

The data that we get back
generate a point cloud.

NARRATOR:
Billions of data points

form a 3-D measurement
of forest volume--

and the carbon stored within.

FATOYINBO AGUEH:
It's so dense that italmost looks like a photograph.

It's like science fiction.

NARRATOR:This scan may look like reality,

but this is data.

It reveals that in an area
the size of a football field,

these trees are storing roughly

150 tons of carbon,

all pulled out of thin air.

Which prompts Tom Crowther
to ask:

could we enlist trees
in the race to draw down CO2?



CROWTHER:
Our lab is urgently
trying to figure out

how we increase the area of
forest across the globe

to capture as much carbon as
we possibly can

in the fight against
climate change.

NARRATOR:
Tom's findings began with
a surprising discovery.

CROWTHER:
We thought there was around400 billion trees on the planet.

But we showed that

there is in fact around
three trillion trees.

There's more trees
on the surface of our planet

than there are
stars in the galaxy.

NARRATOR:
The big question is,

how many more trees
could we add?

CONSTANTIN ZOHNER:
In order to understand
the global forest system,

we need to map a lot of things,

we need to know
where forests are,

where forests could be.

CROWTHER:
We collect our data from

millions of locations
around the world,

where scientists have been
on the ground

evaluating those ecosystems.

NARRATOR:Data like leaf fall patterns in
forests around the world.

I'm trying to understand
the seasonal rhythm of plants.

NARRATOR:
Microscopic organisms like

the tiny worms that feed
the soil beneath the trees.

JOHAN VAN DEN HOOGEN:
In just this clearing,

there is millions
and millions of nematodes

living in the soil.

NARRATOR:
And decades of satellite data

on factors like
rainfall and temperature.

When I look at ecosystems
most of the time,

I'm looking from the top down.

CROWTHER:
And with all of that data,

we can start to see
the patterns across the globe.

Using remote sensing information
from satellites

and machine learning
technologies,

we can generate maps
that can predict which regions

can support new trees
and which ones cannot.

This really is
a data revolution.

NARRATOR:
The detail is astonishing.

And the potential
for new forests is vast.

CROWTHER:
Outside of urban and
agricultural areas,

there's room for about

2.5 billion acres of forest.

ZOHNER:
The area we identified equals

the size of the United States.

So there is a huge area
available for restoration.

NARRATOR:
Enough space for

1.2 trillion new trees,

all sucking CO2 out of the air.

CROWTHER:
If we were to restore
a trillion trees,

the right types of trees
in the right kinds of soils,

and have them grow
to full health,

they could store an additional
205 gigatons of carbon.

NARRATOR:
To put that into context,

we've released nearly

660 gigatons of carbon
into Earth's systems

since human industrial activity
began.

CROWTHER:
Restoring global forests

and conserving the vital forests
that we currently have

could take a huge chunk
out of that excess carbon.

This is a really massive carbon
drawdown solution.

And we knew that this was going
to make an enormous splash.

NARRATOR:
But these findings
also made waves.

(wildlife chittering)

FATOYINBO AGUEH:
That study is causing
a lot of debate.

On the one hand,

a lot of people
are talking about

the potential of
restoration of forests.

On the other hand,

I would say, um, a lot of people
are very upset about it.

(bird cawing)

The uncertainty around
the amount of carbon

that's stored in trees
is so high

that we can't really make
any informed recommendations

on how many trees
we need to plant.

NARRATOR:
Lola wants to use
new technology from NASA

to fill those areas of
uncertainty with hard data.

FATOYINBO AGUEH:
We have over 20
Earth-observing satellites

right now from NASA alone
looking at our planet Earth.

But what we're seeing
is all in two dimensions.

What we're missing here
is the third dimension.

NARRATOR:Enter a powerful new tool called
GEDI.

With the same laser technology

used in
her terrestrial scanners,

Lola can get a three-dimensional
measure of forest carbon

from the
International Space Station.

FATOYINBO AGUEH:
GEDI stands for

the Global Ecosystem Dynamics
Investigation,

which is what you're seeing
right here.

This is about
the size of a fridge.

You can see the lasers
shooting down

out of the bottom of
the instrument

towards
the surface of the planet.

We actually can see

a full profile
of plant materials.

The game-changer here
is that

this is going to be,
for the first time,

a near-global data set.

NARRATOR:
GEDI will give clearer insight

on the carbon new forests
could store.

But equally important,
it can pinpoint

the old forest carbon
we must preserve.

FATOYINBO AGUEH:
Forests are really important

for our water supply,
forests protect us from heat,

forests breathe.

They breathe in some ways
just like we do.

When you lose a lot of

the ecosystem services
that forests provide,

that has a direct impact
on the well-being of people.

NARRATOR:
But on an increasingly
populated planet,

trees are not the only living
things competing for land.

We already use all of our
agricultural land

to feed our existing population,

and over the next 30 years,food demand is going to double.

If you take land
to solve the climate problem,

you create another problem.

NARRATOR:
So, is there a solution

that can solve more than one
problem at a time?

WHENDEE SILVER:Some people are looking at ways

in which forests
can help slow climate change.

Our research
is somewhat different

in that
we're looking at grasslands.

I want to have enoughso that we can do experiments.

NARRATOR:
In California, Whendee Silver
is looking for a way to

pull down CO2 right where

we grow our food--

Earth's grasslands.

SILVER:
This is a classic, beautiful
annual grassland.

Grasslands grow in places

where there's drought
for part of the year.

And these grasses
have developed

great tools
for getting water,

particularly
by growing more roots.

And any time plants invest a lot
of their energy into roots,

it's like injecting carbon
into the soil.

NARRATOR:But tilling releases that carbon
and degrades the soil.

And producing our food

creates even more problems.

SILVER:
We all eat food every day.

We have to grow that food.

And we create a lot of
organic waste in the process.

(birds cawing)

NARRATOR:
When organic waste
sits in a landfill

or slurry pond,

it creates
an oxygen-deprived environment

favorable to certain microbes,
which in turn produce methane,

a greenhouse gas
34 times more potent than CO2.

We're trying to tackle
three big problems:

waste, degrading soil health,
and climate change.

We came up with something
relatively simple:

composting.

NARRATOR:
In composting,

food waste
is regularly turned,

adding oxygen to the mix
and keeping the

methane-producing microbes
at bay.

SILVER:
It creates this organic and
nutrient-rich resource,

like a slow-release fertilizer,
that helps plants grow.

NARRATOR:
By turning a waste into
a nutrient,

compost can boost
plant growth

and potentially turn vaststretches of Earth's food crops

into a carbon-storing
juggernaut.

(indistinct talking)

Can you grab that?

SILVER:
We now have ten years of data

showing that just
a one-time dusting of compost

onto the soil surface

can have a long-term impact
on plant growth

and increase carbon storage
in soils.

NARRATOR:
Whendee's research shows that

a single layer of compost

can increase plant growth
by up to 78%

and increase soil carbon by
up to 37% for three years.

SILVER:
The real challenge is

to extrapolate from little tiny
soil samples in the field

to big chunks of
California or the globe.

That's a huge challenge.



NARRATOR:
As the hunt for solutions

continues in the decades ahead,

stopping our emissions remains

the most urgent challenge
of today.

KEITH:If we really didn't do anything
to limit carbon emissions,

we would have climate changes
as big as the changes

from the glacial
to interglacial state

and do that
in one human lifetime,

with huge potential impacts.

The more of a mess we make,

the bigger of a mess
we'll have to clean up.

We today get to decide

whether to
continue along this path...

Or to dramatically shift

our economy
off of coal, oil, and gas.

EXTAVOR:
Every big transformative
solution starts small.

It starts with
a couple of people talking.

They make a small version,

they make a bigger version,
more people pile in.

ZOHNER:
This is one solution,

but we need
thousands of solutions

if we want to tackle
climate change.

SILVER:
There's no one magic

silver bullet
that will solve this problem.

SINHA:The main challenge that we have

is that these transitions
don't happen overnight.

SNAEBJORNSDOTTIR:
We have the tools already,

but we really
have to start moving.

DENNING:
We need better
transportation systems.

We need solar power
and wind power

and water power,
and probably nuclear power.

We need to plant trees.

We need to
manage our farms better.

We need direct air capture.

I think
we probably need it all.

LONG:
We have to start really
looking at what can scale up

and be maintained--
for decades, if not centuries.

That's the challenge here.

But it's anincredibly important challenge.



PACALA:
15 years ago,

no one would have predicted that

the emissions in developed
countries around the world

would be dropping.

Not fast enough yet,

but that gives me hope

and should give everyone hope

that with the combined
might of human ingenuity,

we can actually
solve this problem.





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