Future Tense

What’s the Deal With Geoengineering?

Your 101 guide to the maybe-crazy, maybe-sane attempt fix climate change by tinkering with Earth’s atmosphere. 


Geoengineering is how some scientists suggest we might slow the effects of climate change.

Photo by iStock

Welcome to the first installment of Futurography, a new monthly course from Future Tense that aims to help you navigate discussions about the technologies that will define tomorrow. In January, we’ll be discussing geoengineering. Can we stop climate change by tinkering with the atmosphere? Future Tense will help you understand the debates and the science behind geoengineering.

I keep hearing about this geoengineering thing. What is it, exactly?

At its simplest, “geoengineering” is the active transformation of our planet’s climate through human intervention. (Click here for a cheat sheet.)

Am I crazy for thinking that sounds like something a Bond villain would propose?

Not entirely, but at least its proponents’ intentions are altruistic: The field emerged in earnest in the last two-and-a-half decades as a response to global warming and other forms of environmental degradation. It’s about using technology to solve crises created by other technologies, everything from filters that pull carbon dioxide out of the air to spraying chemicals that would lower the global temperature.

Though these efforts are relatively new, geoengineering as such has arguably been under way for much longer. As the science-fiction writer Kim Stanley Robinson puts it, “Our current technologies are already geoengineering the planet—albeit accidentally and negatively.” Our cars, our factories, and our whole way of life are transforming our climate and everything that conditions it. Proponents of geoengineering hope to make that process more deliberate—and its effects more positive. Conversations about geoengineering have become increasingly urgent as the consequences of climate change grow unavoidable.

That sounds less terrifying than I expected. Why does it have so many people up in arms? Is it even doable?

Geoengineering is controversial precisely because it is surprisingly practicable. Its proponents and critics both point out that it is based in real, actionable science: If you inject sulfuric acid into the upper atmosphere or dump iron into the oceans, things will happen. But these and other proposed techniques are still poorly understood and highly experimental.

There are two primary approaches to geoengineering: The first, carbon dioxide reduction, would pull CO2 out of the air to prevent warming in the first place. The second, typically known as solar-radiation management, aspires to bring down ever-rising global temperatures by reflecting a portion of sunlight back into space. Both are promising, but even their most dedicated advocates insist that neither is a panacea. Geoengineering is a stopgap, not a solution.

Strictly speaking, both forms of geoengineering are possible without new innovations, though it might be necessary to advance and scale up existing technologies if we hope to make them truly effective. Indeed, some geoengineering practices are surprisingly low-tech. Painting rooftops white, for example, might help cool cities, and changing our forestry practices could reduce atmospheric CO2. Nevertheless, most discussions of geoengineering focus on more drastic approaches.

Carbon dioxide reduction sounds cool. Tell me more about that?

Sure. Researchers generally agree that artificial carbon dioxide reduction is both the most promising and the safest method of climate intervention. Even if we collectively switch to more environmentally friendly energy production methods, carbon dioxide reduction could be crucial. Without it, we’ll be stuck with excessive atmospheric CO2, even if we stop adding more to the atmosphere, because without any intervention, it would take decades, maybe even centuries, for things to return to the way they were prior to the Industrial Revolution.

Two prominent carbon dioxide reduction methods are currently under discussion. The first, direct air separation, would filter CO2 out of the air, making it possible to safely contain the gas. The second, known as biological carbon dioxide reduction, would involve planting crops that naturally collect CO2. On reaching maturity, when they stop absorbing CO2, these plants would be burned, and the resultant gases passed through a filtration system, not entirely unlike that used in direct air separation. Whatever the method, once extracted this CO2 could be pumped underground or repurposed as an environmentally friendly fuel.

Great. Let’s do it!

If only. While both of these reduction strategies are possible with current technology, they remain prohibitively expensive, making it difficult to implement them on a meaningful scale. A handful of small startups—including Global Thermostat and Carbon Engineering—are working to push the technologies forward in ways that may reduce their cost.

That sounds like tricky stuff. Is there a simpler way?

Another notable method of carbon dioxide reduction is ocean fertilization, which involves artificially stimulating the growth of plankton that naturally absorb CO2. Sometimes described as “biological pumps,” these organisms ultimately sink into the ocean, removing pollutants from the air. But present methods may be dangerous to fish, sea birds, and other forms of marine life. It could also produce a variety of other harmful environmental effects in the process of removing CO2 from the air.

What if we want to do something more immediately?

In the short term, at least, solar radiation management seems to be the much more plausible approach to geoengineering, but it too presents a variety of serious risks. Instead of directly confronting the causes of climate change, solar radiation management seeks to ameliorate some of its effects, reducing temperatures by manipulating the albedo

Hold up. Albedo?

That’s a technical term for the reflection of sunlight into space. Changing it on a large scale could significantly reduce global temperatures, but it wouldn’t do anything for the other effects of excessive atmospheric CO2, such as ocean acidification. We’re talking about symptom management here, even more so than with those carbon dioxide reduction technologies.

So is this even a good idea?

It might not be. In fact, when you hear scientists worrying about geoengineering, they’re typically talking about solar radiation management. But compared with carbon dioxide reduction, albedo modification would be relatively inexpensive. Arguing for this approach in his book A Case for Climate Engineering, Harvard University professor David Keith writes that “a well managed program could likely be ready to start by 2020 [for] a total budget of roughly a billion dollars.” While that price tag would rise rapidly, this means that a moderately prosperous nation could, at least at first, attempt to modify the albedo on its own.

There’s a Bond villain component here, too: Keith talks about flying custom-built Lear jets into clouds to inject them with chemicals. And Nathan Myhrvold has a plan that he calls the Stratoshield, which involves hoisting enormous acid spraying hoses into the upper atmosphere with balloons. It’s just crazy enough that it might work. Really.

I feel a big “but” coming …

But not everyone thinks geoengineering is reasonable; climate scientist Raymond Pierrehumbert even described solar radiation management as “barking mad.” As CO2 levels continue to rise, solar radiation management campaigns would have to escalate. If they should cease at any time, even for a period as short as a year, global temperatures would spike suddenly with likely catastrophic effects. Basically, any commitment to albedo modification would have to last for millennia. Other, more immediate, concerns include the possibility that it would negatively affect rainfall or damage the ozone.

Where does this leave us?

Even geoengineering’s more cautious proponents tend to argue that the field requires further research and clearer international standards before any we deploy any version of it on a global scale. However, even if we are able to safely implement some of these strategies, the greatest risks may be social. As many have observed, ameliorating the effects of climate change may create the illusion that it’s no longer necessary to fight its root causes. As the sci-fi writer Robinson has suggested, human engineering—transforming the ways that we live—may ultimately be the only truly effective form of geoengineering.

OK, so what’s next?

Well, to some extent that’s up to you! Future Tense will be exploring this topic for all of January, and we’re eager to help you understand it better. What still puzzles you? What other questions can we answer? Most importantly, what do you think?

This article is part of the geoengineering installment of Futurography, a series in which Future Tense introduces readers to the technologies that will define tomorrow. Each month from January through May 2016, we’ll choose a new technology and break it down.

Read more from Futurography on geoengineering:

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