was an absolutely crazy idea and even considering this was really quite out there.

For a long time it was considered kind of a fringe or a whacky idea. For a couple of reasons. In

part this stuff sounds like science fiction. And it also sounds like a desperate type of

human response. The more I learned about climate change and where that is taking us and humanity,

the more I got worried about this. If in 10, 15 years humanity finds itself in a real crisis

and populations really demand that decision makers take action now, not words, but actions.

Then one of the few things you can do to take fast action is stratospheric geoengineering.

And I think if we haven't done research on this, despite how crazy this idea is, then

that’s a really bad idea. In the end, the risk of not doing research on this may be bigger

than the risk of doing research.

Climate engineering is an umbrella term for a set

of imagined technological responses to climate change. And I say imagined because most of

the technologies that are being talked about are only on the chalk board at this point. The

latest frontrunner is solar geoengineering, a plan that would disperse particles into the

stratosphere and could reduce global temperatures by bouncing the Sun's rays back into space.

It's an idea that picked up steam over a decade ago when a famous scientist called for more

research. Crutzen won the Nobel Prize for his work on atmospheric chemistry of ozone

depletion and he wrote a paper which made the case for investigation into solar geoengineering

as a response to climate change. Basically he said we're not getting there fast enough

just with political means. So we scientists and technologists have to see that there are

additional things that have to be done. There's a previous report by the IPCC and what comes

out of that is fundamentally in just a few years, our emissions have to be zero not half

in 2030 and zero in 2050. And I'm like, well there's absolutely zero chance this will happen.

With growing urgency and scientific interest, a team at Harvard University took up the charge

to investigate solar geoengineering in a fully fledged research program. From my perspective,

before you perturb a system, it probably is a good idea to understand the system.

So one has to understand that in a climate system, everything is coupled together. Where we

live in the troposphere there's a huge variety of particles. It turns out in the stratosphere

it's much, much simpler. You have emissions of sulfur containing compounds in the troposphere.

They make their way up all the way into the stratosphere. They find each other and start

making little particles. That's the natural aerosol that exists in the stratosphere.

A major source of these sulfur compounds are volcanic eruptions. When Mount Pinatubo erupted

in the Philippines, it blew nearly 20 million tons of sulfur dioxide into the stratosphere.

That surplus created a blanket that cooled the Earth by .5 degree Celsius for roughly

15 months. Scientists see this as a proxy for solar geoengineering’s potential, but

these sulfate aerosols come with consequences. We know that on these highly acidic surfaces

of these aerosols, reactions occur that can result in ozone depletion. We also know based

on the molecular properties of sulfuric acid in water that this absorbs radiation and that

heats up the stratosphere. I'm thinking are there materials that could have less side effects?

This is what Zhen Dai, a PhD student at Harvard is investigating. She built this

table top experiment to explore alternative particles that could potentially cool the

planet and minimize risks to the ozone. Calcium carbonate is interesting mostly because of

its chemical properties. Specifically, it's kind of a common thing that we see everyday,

in toothpaste, a whitener for paper, it's relatively safe for human beings. We use

something called a flow tube experiment where basically, your particles sits on kind of

a tube inside the flowtube there. And you have an injector that comes in through the tube.

We basically push the injector upstream of the particles so that the gas would interact

with the particles. We suspect that if we put those calcite particles into the stratosphere,

they might interact with the acidic species, such as hydrogen chloride, and sequester some

of those. Those species happen to be related to ozone loss. Even with this experimentation,

the Harvard team is aware of its limits. How much trust would anybody have that these researchers

at Harvard have replicated the complexity of the stratosphere in their little flow tube

of one meter? I would hope most people would say, "Well, I don't quite know whether that's

sufficient for me to put my trust in." I'm not going to tell the world, you know, "Yes,

just trust my lab results." I want to know how it actually behaves. That means you have

to intentionally put some of it into the stratosphere.

SCoPEx is the Stratospheric Controlled Perturbation Experiment.

We're going to have a balloon that's

going to be at 20 kilometers. And below that we are going to have what we call an equipment

gondola that's hanging here. It will have all the instrumentation in it. In there we're

going to have a system to disperse aerosols a few hundred grams of calcium carbonate.

Less material than a normal airplane flight actually puts out in the atmosphere. It makes

what we call a plume behind it. What we want to do is then turn around and fly back through

this plume at various points in it. And that actually in a way is a little bit like a flow

tube in the lab. It is a truly small experiment. From the material we're going to place there,

it will have absolutely zero impact on the ground. But, the idea is that we'll be able

to learn does the air around our particle evolve the way we think it should based on

our lab model? I want to actually find out as much as possible what are the effects of

doing this and risks. We're slowly getting these things together. We will test them in

the lab. We have a big chamber where we can reduce the pressure to stratospheric pressures.

We're just at the beginning of thinking about how to do these experiments.

Before it even takes flight, the Harvard team set up an advisory committee that’s acting as an independent

check on their developments. We want to try to have SCoPEx not just be an experiment that

can advance science of geoengineering, but to also make sure that it's done in a way

that tries to exemplify good governance. One thing to make clear is that even if we're

technologically ready we're going to have to wait for the advisory committee and see

whether they think that we've really done all the things they expect us to do with this.

Solar geoengineering was recently on the agenda at the UN Environment Assembly

to kickstart a global conversation. Because if a country decides in 10-15 years that they

need to act fast with a massive fleet of aircraft, there are systematic unknowns to bear in mind.

The problem is if we find out, at some point "Oh, there's a big side effect. We need to stop this now.

What's gonna happen is you're gonna jump back up to that steep point in the steeper curve.

That's called termination shock because you've, sort of, given the system

a really hard shock by just stopping. SCoPEx is a very small experiment before we even

get to that scenario. But still, it’s been a lightning rod for criticism. I think the

reason SCoPEx has ignited so much controversy is not because of the actual physical impact,

but the symbolism of the experiment. The first is the so called slippery slope. If you start

with a small scale experiment then that just kind of opens the door to larger scale investigation.

The second reason is that lots of folks see this type of work as a distraction from what

they think really needs to happen: emissions abatement, adaptation, that's where the game

should be. And something like solar geoengineering might serve as an excuse for some people to

kind of take their foot off the gas pedal on those more important forms of climate action.

And with this conversation, comes another source of controversy. The chemtrails conspiracy

suggests that solar geoengineering is already taking place through this chemtrails activity.

That's a myth. Chemtrails are not a real thing. I know lots of people are going to disagree

with me on that, but there's no scientific evidence.

If this research effort shows geoengineering’s

benefits outweigh its risks, it could potentially reduce global temperatures. It would not fix

the root cause, which is the rising funnel of greenhouse gas emissions that are getting

trapped in our atmosphere.

I think if we're not having strong action on emissions, pursuing

stratospheric geoengineering is quite risky because then, we have this mirage of something

that helps us. The only reasonable way to even consider something as contentious as

this is as one small component of a portfolio of response options. Often consideration

of climate change is not based on science. It's based on ideology. It's based on our

belief systems. If you believe that human beings got into this mess because they're

hubristic and because technology has run away from us, then you're probably opposed to even

consideration of solar geoengineering. It just seems like a bad idea. If on the other

hand, you believe that scientists are the last bulwark that we have against coming climate

chaos, then you might give license to scientists to do investigation in this area, because

we need to know what's out there. It's these clashing worldviews that makes the consideration

of solar geoengineering, and frankly climate actions writ large, so contentious. I really

hope humanity gets its act together and actually goes after solving their problem fast enough

that in the end we will never have to consider actually doing this. But I'm not convinced we're doing this.

The ability to solve global problems as a global community has not improved in the last

years and that makes me even more concerned about this

and that we will not be able to fix this problem in time.