♪
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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♪