Do you think climate change is complicated? Learn about solar geoengineering

This story was originally published by Cabling and appears here as part of the Climate Table collaboration.

Here’s the thing about the stratosphere, the region between four and 50 kilometers in the sky: if you really wanted to, you could make it pink. Or green. Or what you have. If you sprayed any dye up there, the stratospheric winds would blow the material up to engulf the balloon. After a year or two, it would fade and the sky would turn blue again. Neat little joke.

This is the idea behind a solar geoengineering technique known as a stratospheric aerosol injection, only instead of a pigment, engineers would spray a sulfate that bounces some of the sun’s radiation back into space, an attempt to cool the planet. It is the same principle behind a supervolcano that charges the stratosphere with aerosols and blocks the sun. And it would also depend on those winds distributing the material evenly.

“If you do it in one place, it will affect the entire planet,” says climate scientist Kate Ricke, who studies the intersection of geoengineering, human behavior and economics at the Scripps Institute of Oceanography. “Not only because the global energy balance has cooled and changed, but because the particles are scattered.”

While it’s not likely that someone will color the atmosphere anytime soon, it is increasingly likely that someone will decide that it is time for the stratospheric aerosol injection. Emissions are not declining anywhere near the rate necessary to prevent global temperatures from rising 1.5 C above pre-industrial levels, and the climate crisis worsens.

But science not ready. This anthropogenic geoengineering It could trigger unwanted effects, such as droughts in certain regions and massive storms in others. Also, if engineers abruptly stopped spraying aerosols into the atmosphere, temperatures would return to where they started, potentially endanger crops and species.

Still, stratospheric aerosol injection would be pretty cheap. And there is nothing stopping countries from unilaterally deciding to spray their airspace, even though those materials would eventually spread across the world. “It’s just hard for me to see with the economy how it doesn’t happen,” says Ricke. “For me, that means there is really an urgent need to do more research.”

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WITH CABLE sat down with Ricke to talk about the charm and possible dangers of geoengineering, what makes it so politically dangerous and how scientists can make sense of it, for the good of humanity and the planet. The conversation has been condensed and edited for clarity.

Can you give me an idea of ​​the scale that we would be talking about with solar geoengineering, both on spatial scales and on timescales?

Let’s say you want to start geoengineering today to stabilize global temperatures where we are, or maybe lower them a bit. Basically, you need a fleet of planes that can reach the stratosphere. We are talking about a scale of perhaps tens to hundreds of aircraft and the ability to spray aerosol precursors.

But the way the stratosphere works is that once you get there, stratospheric winds carry things around the planet relatively quickly in bands of latitude. And then slowly, over time, on a timescale of months, things generally migrate from the equatorial regions toward the poles, and then the particles fall near the poles. So you wouldn’t need to be flying through all the stratosphere spray material. The stratosphere does a lot of work to spread it out. And that’s part of the reason you can’t do stratospheric geoengineering in just one area.

Would we notice this? Visually, would we see anything?

Yes, on an absolute scale. Change the ratio of direct and diffuse radiation. So the idea is that the sky on average would become a little whiter and, for example, sunsets would become a little more vivid. It is definitely much smaller than the difference between going from the California desert to the city. The white skies thing isn’t, in my opinion, probably the biggest problem either.

What about concerns about toxicology? Is this benign for living creatures on Earth?

It is not benign, it is the same thing that comes out of power plants. Large concentrations in an area make people and crops sick. But, in terms of scale, the amount you need in the stratosphere is much, much less than what we emit from power plants, and it is spread across the entire planet.

People have done some studies on this too, and it seems likely the biggest risk from particulates would be a kind of high-latitude sensitive ecosystems, so polar ecosystems are not very exposed to urban pollution at the moment, but that they would. Get more out of this. Especially since the particles generally move toward the poles before rushing out of the stratosphere.

Let’s say a country unilaterally says, ‘We’re going to do this.’ They want to cool their own country by spraying the stratosphere, and it doesn’t matter if it’s going to engulf the planet.

Legally, it is complicated, because countries own their airspace until space, basically. It is a bit ambiguous. So that people could sprinkle things on their country and go everywhere. And then [the particles] stay in the atmosphere for a year and a half on average. They spread and the radiant effects take effect immediately. That is why after a large volcanic eruption, you see a drop in global temperature immediately that persists for about a year or two and then falls again. So you wouldn’t need to spray things every day, necessarily. If you stopped doing it for two years, the effect would wear off.

I find it hard to see how we are no I’m going to do it at this point, actually, because it’s so inexpensive. The impacts of climate change already seem to be so disruptive that I don’t see in this world how someone doesn’t implement such a low-cost solution. There is nothing else in the world that can cool the planet so quickly. Even if we started to decarbonize quickly and remove CO2 from the atmosphere, it is still a decade for the consequences. Whereas by blocking sunlight, the climate response begins immediately.

I’ve seen some models that if you suddenly stopped solar geoengineering, you’d have a problem with temperatures. Climbing and threatening species.

If the show was interrupted and we were blocking a lot of warming with stratospheric geoengineering, you’d get this warming really fast if someone stopped doing it. I mean, it would be catastrophic if we also stopped treating our drinking water, right? There are things that humans do and we must continue to do, or it is catastrophic.

The technology is not so complicated that we just need the person who developed the technology to continue to do so. So I’m a bit skeptical that that argument is the biggest problem because we basically already know how to do it. It is within the reach of a medium-sized country or something like that. The resources are significant enough that it is difficult for a single person, or a very small country, to do so. But it’s not like nuclear weapons or something like that.

Are we getting to the point where the science is solid enough that we can begin to make these decisions? And will that be possible, given the general lack of cooperation at the international level?

There may be some technical experts, like myself or others who have worked on this, who would say, ‘Yes, I’ve seen enough to believe it.’ But to have a collective decision-making on a global scale, you need a science that everyone considers legitimate. No everybody, but many people. And we are not there, far from it, with geoengineering.

But that is why we need more research. And we need more diversity of who is doing research and where, because the results will need to be seen as legitimate by a much broader group of people. They are not now. That is definitely not true.

Why not?

Because it’s been a small group of mostly elite white college students in North America and Europe who have done all the research. And people just don’t automatically trust a small group of elites like that. In fact, it is important that the Bangladesh Ministry of the Environment have someone who is from Bangladesh and talk to them about the science of geoengineering. So I think that’s the biggest problem with science right now. You can look at certain areas of climate science and you will see that we are saying the same thing over and over again. But that has also had some value: replication and repetition. Build consensus and build trust in science.

National commitments to reduce emissions they are one thing, but this involves everyone simultaneously because we share an atmosphere. Will there be an agreement on that?

We are not there where we can have a global consensus on geoengineering, far from it. But I guess this is more likely to happen no with a global consensus. Certainly there are some actors who, if they did, would be limited by more powerful actors. But there are definitely other major players in the world that already exist that could geoengineer and get away with it. Because the alternative is: Is it bad enough for you that you’re willing to go to war over it?

What about moral hazard? Wouldn’t geoengineering reduce the urgency of reducing emissions?

Moral hazard is a totally valid and very important concern. In terms of the existing empirical research, the results are very mixed. It doesn’t seem like [for] Individual humans, when you put them in behavioral experiments, there is a moral hazard surrounding geoengineering. Talking to people about geoengineering in a controlled way tends to make people want to mitigate greenhouse gases more because people think geoengineering is kind of crazy and scary. They see it as an indicator that climate change is a big problem.

I’m the editorial writer on my fellow climate scientists, but I think most climate scientists don’t like the idea of ​​geoengineering. And the reason they still don’t like it more is because of moral hazard. They think we have to tell people ‘This is a bad idea’ for as long as possible because of that. And they are probably right. But the risk is that if things get bad enough with climate change, people are going to geoengineer anyway and we won’t be prepared to do it.