Our “Marketplace Tech” series “How We Survive” explores how tech can help the world adapt to climate change. In this installment, we look at what it’ll take to keep the Earth from getting 1.5 degrees Celsius warmer. 

To keep the Earth’s temperature from continuing to rise, we’d need to figure out how to suck hundreds of billions of tons of carbon dioxide out of the air. And that’s just the one fix.

Such technologies, known as geoengineering — manipulating Earth’s climate to try to fix a climate problem — do exist, many in early stages. I spoke with Solomon Hsiang, who directs the Global Policy Laboratory at University of California, Berkeley, which has studied the potential and possible consequences of geoengineering. He said there are some promising lines of research. The following is an edited transcript of our conversation.

Solomon Hsiang: One that people talk about is just trying to suck CO2 back out of the atmosphere, maybe burying it as a liquid underground. There’s other approaches, trying to keep things cool. The Earth is heated up by the sun every day, and the greenhouse effect occurs because we put up CO2 into the atmosphere and it traps heat near the surface. One way to counteract that effect would be to put stuff up in the atmosphere to reflect some of the sun away from the planet before it ever gets into the atmosphere and hits the surface. That approach is called solar radiation management. That’s probably the thing that people discuss the most.

There’s a couple different ways people talk about achieving that. For example, we know from previous volcanoes that if you spray dust high up into the atmosphere, it reflects a lot of sunlight, and that can cool the surface. That’s happened in the past when big volcanoes erupted — Mount Pinatubo, for example. We know that would work, and people have talked about whether we can do that intentionally — maybe flying planes and releasing aerosols into the upper stratosphere. That’s something that people are actually talking about and debating different strategies and various costs and benefits. That’s becoming quite real.

There’s other more natural-sounding approaches. For example, there’s an idea called cloud brightening, where you take maybe boats out in the ocean, and you try to release particles into the atmosphere or spray mist — fine mist — basically making clouds brighter white so they reflect sunlight back out into space. These are all different strategies people have talked about [and] are trying to think through what’s practical and what’s feasible, what might be cost effective, what might be dangerous.

Molly Wood: Let’s talk about the dangerous part, because it is really easy to go to imagining serious unintended consequences of manipulation at this level. Talk to me about what we want to avoid.

Hsiang: There’s a growing body of research where people are trying to think about different unintended consequences. For example, one unintended consequence is that if you change how sunlight is coming in, it actually affects the weather patterns, and it will change where rainfall falls. People said, “Well, we might geoengineer in such a way that the planet stays cool, on average.” But then some people who have farms in the areas where the rain stops falling, they’re going to be losers if we implement this strategy.

We did a research project where we tried to understand what is the economic value of all the sunlight that’s coming in. If we start reflecting sunlight back out to space, we’re throwing away a valuable resource — we use that sunlight to grow the world’s crops and feed humanity. Then there’s stuff that’s not an unintended consequence, but it doesn’t address all the problems of climate change. Putting CO2 in the atmosphere causes ocean acidification, because you’re changing the actual chemistry of the ocean. If we spray dust up, we can keep the surface cool, but the ocean will still become acidic. There’s some concern that no one knows what that will do to coral reefs, fisheries and ecosystems. There’s a lot of concern that we might become reliant on geoengineering because it helps humans stay healthier, for example, but it’s not really going to fix, it’s not a holistic solution to the problem.

Wood: As I hear you talk, you’re clearly talking about solutions that would have a global impact and that would, I assume, require some global cooperation before they could be deployed, which feels like another pretty big barrier.

Hsiang: You would like to imagine that we would agree on some sort of strategy before deploying, but in reality, I don’t know that that’s necessary. A lot of people worry that as the climate changes, some locations realize that they are getting the short end of this bargain. Hot countries, for example, suffer the most when it gets hotter. Those countries have the biggest incentive to try and keep things cool. They may want to get started geoengineering before other countries feel like it’s worth taking on those types of risks.

We don’t really know, we’ve never tried to have these global bargains, but we’re going to. Right now, we’re trying to create a global bargain to reduce climate change, and that’s only been moderately successful. This is opening up a whole new world of political science thinking, people trying to understand how should we design these treaties? If a country unilaterally decided to start geoengineering, [it] depends on what kind of activity it is. If they’re sucking CO2 out of the atmosphere, that actually could benefit everyone, but that’s one of the most expensive strategies. If people started trying solar radiation management, it might keep their country cooler, but it would affect other countries — it might make other countries too cold. We don’t have a plan for who gets to control the thermostat.

Wood: How far along are we toward having a plan?

Hsiang: We don’t even have a plan for a plan.

Wood: OK, that’s terrifying.

Hsiang: There’s been a lot of scientific research on this, and people are only now in the policy space recognizing the market forces that play, realizing that we have to take this very seriously. It’s no longer just like a fringe science fiction idea. It’s something that people are actually talking about trying.

Wood: I would also imagine that if these efforts, even some of them are successful, would they then give countries or companies license to keep polluting? If we have a mitigative technology that’s that effective?

Hsiang: That is a big fear. I think people think about that a lot. … Sometimes people drive a little more dangerously because they know they have a seat belt. The concern is that people will behave more recklessly, they won’t think about the future in the same way if they hope that technology can rescue us. It’s a big fear, and I don’t think it’s without grounds. It’s a real thing. It’s also, on the other hand, not a great reason not to try to understand what geoengineering can do for us. Just because you’re afraid that people might drive more dangerously because they know they have an airbag doesn’t mean you shouldn’t invent an airbag. You’d want to have that in case you got into an accident. It’s a tricky balance: How do we keep people motivated to reduce emissions, at the same time trying to think about contingencies for these worst-case scenarios?

Wood: It sounds like you’re saying, too, that we at least have to explore geoengineering as a solution, right? How much does it need to be in the mix?

Hsiang: It is absolutely something that we should be thinking about and doing active research on. I think the worst-possible-case scenario would be we arrive in the future, we still have climate change, people really want to do geoengineering and we know nothing about it. As scary as geoengineering sounds, the way I describe it to people often is it’s a lot like chemotherapy. It sounds terrible in lots of ways, but not taking the treatment and suffering the disease might, in some cases, be much worse.

Related links: More insight from Molly Wood

We have more reading on geoengineering and how the science and the controversy have developed over the years, including a story from 2015 written by our very own “Marketplace Tech” producer Matt Purdy. 

Like I said, everyone agrees that geoengineering is, as Solomon Hsiang puts it, a chemo-like solution to the climate problem. But more and more scientists are starting to approach it as a necessary evil. However, last March, when the United Nations proposed a resolution to try to gather more information about geoengineering — maybe like the plan for the plan that Hsiang talked about — the United States, along with Saudi Arabia and Brazil, blocked the measure.