Yes

Governments should consider solar geoengineering for two reasons. The first is that other ways to avoid the worst effects of climate change may not prove achievable in the world as it really is. The other is that, if there is a risk that another government might attempt to transform the atmosphere, it would be delinquent not to have thought through how to react. That means trying to understand what the effects of such engineering might be on your own country and the world.

There is little doubt that lacing the stratosphere with particles that reflect sunlight back into space would decouple Earth’s surface temperature from greenhouse gas levels, allowing for cooler temperatures than otherwise would occur. On a planet with greenhouse gas levels expected to deliver 2.5 degrees Celsius of warming above pre-industrial levels, solar geoengineering could in principle limit the actual warming to 1.5 degrees Celsius. It could also allow temperatures to be decreased even as greenhouse gas levels stayed the same or declined only slowly. Both of these possibilities seem, on the face of it, worth examining as ways to avoid global catastrophe.

But there are also other, more disturbing possibilities. One is that solar geoengineering might be used to keep temperatures the same even as greenhouse gas levels continue to rise, allowing some or all countries to shirk their commitments to cut their net emissions to zero by mid-century. Perhaps even worse is the possibility that simply raising the prospect of solar geoengineering could reduce progress on emissions cuts and curb the development of all other ways to limit temperature rise.

When I worry about the possible impacts of solar geo­engineering, I worry most about that last scenario. It’s a fear that I share with many who see it as a reason for the governments of the world to come together and pledge never to embark on a solar geoengineering project. But that argument is both impractical and paradoxical. It is impractical because no country can be assured that every other government will abide by the constraint in perpetuity. And it is paradoxical because if I believed that the governments of the world could be trusted to unite in solidarity and unanimity, then I would believe that they could then be trusted to deploy a modicum of solar geoengineering and slash emissions at the same time. The possibility of such self-denial undercuts the argument that governments are so reckless that a ban is needed.

If governments should pursue solar geoengineering because they cannot be sure that others will refrain and because of the chance that it could reduce harm, how then should they move forward?

The obvious answer is through sustained research aimed at understanding as much as possible about the effects of solar geoengineering on factors other than global temperature. What could such technologies mean for the water cycle in various regions, for changes in seasonality, or for extreme events? How might they be implemented in ways that maximize benefits and minimize risks?

But research alone is not enough. The dangers—including that of a diminished appetite for emissions cuts—and the rewards of solar geoengineering do not fall on the same people, the same countries, or even the same generations. To fully consider geoengineering would be to ask questions about who it could be made to benefit and how. It would be to evaluate the contexts in which it might be justifiable and the contexts in which it should be resisted. It would be to ask whether it could be carried out in a safe and just way—and under what circumstances and modes of governance it might be likely to exacerbate tensions to the point of war.

Part of me thinks that this consideration could be a grand thing: a way of debating the great issues of the Anthropocene, what it means for democracy to enter into the arena of the Earth system, and the role of politics and purpose in the planetary economy. But I acknowledge that I am much too tempted by such ideas. The sort of consideration I envisage would be endlessly pressured by other issues, endlessly at risk of being derailed or suborned by fossil fuel interests. To hope for something better is not to deny the influence of those who want to maintain the status quo.

But unsatisfactory debate is still preferable to treating the issue as untouchable. “To govern,” the radical French Prime Minister Pierre Mendès France once said, “is to choose.” Choices over moral absolutes require no consideration. In most matters, though, choices are better when options, distinctions, and consequences are considered. The possibilities of solar geoengineering fall firmly into that second, much larger camp.

Oliver Morton

No

Lab-created meat, “bioplastics,” those hideous shoes made out of recycled packaging—the world is littered with Band-Aid fixes to environmental problems. Geoengineering will be the most expensive and potentially the most destructive example of this yet. There’s an enduring trouble with solutions that don’t address the root causes: They’re unlikely to solve the problem and will almost certainly create new ones.

I’m old enough to have reported on so-called clean technology, or cleantech, when geoengineering made headlines around 2008. Then, as now, some leading climate scientists were encouraging governments to invest in geo­engineering research and development. Back then, people talked about seeding oceans with iron to spur plankton blooms that would absorb carbon and then die, pulling the gas along with them to the bottom of the sea. Biochar was big back then, too—turning plant waste into CO2-laden briquettes that we then bury. Even the idea of “synthetic trees” that would capture CO2 and store it in liquid form underground got some buzz.

Today, experiments are still under way for all those carbon capture technologies, including, somehow, artificial trees. But most of the excitement around geoengineering these days is focused on what seemed fringe just a decade ago: solar geoengineering, which attempts to change how Earth reflects the sun’s rays by spraying tiny particles into the atmosphere. A team of scientists at Harvard have been experimenting with this for years, injecting various chemical cocktails into a glass tube containing an exact replica of the stratosphere. In December, they announced plans to take the tests out of the lab and into the Swedish skies as early as this summer.

Around the same time as the announcement, researchers from the Grantham Institute at Imperial College London, Zhejiang University in China, and elsewhere published a study that found that while solar geoengineering could, in fact, cool surface temperatures on Earth, it would also increase the frequency of El Niño and La Niña extreme weather events. Those scientists concluded it was not worth the risk. I should also point out that most of the climate scientists who advocate for geoengineering research have never stopped saying that it’s dangerous. Frank Keutsch, the principal investigator on the Harvard project, for example, told the MIT Technology Review, “I still think this is a very scary concept and something will go wrong.”

Research is always necessary, and we’re at the point where we can’t exactly turn up our noses at technological solutions and assume companies and politicians will suddenly do the right thing. I get that. My concern with geoengineering is that it’s not being accompanied by shifts in policy or investments in less sexy but better-proven energy-efficiency strategies. It’s also being embraced—and in many cases funded—by fossil fuel companies desperate for a fix that doesn’t require them to strand assets or lose profits.

But arguing over this or that approach to address the climate crisis is a fool’s errand. It will not be solved by new technologies laid atop the very system that created it in the first place. Climate change is the sort of problem you end up with when a small number of people have power over the whole world and are incentivized to put their profits before the common good. The problem is the power structure, not the power source.

In the absence of government funding for research into a wide range of climate solutions or even the political will to say that we need to stop drilling for fossil fuels, I’m also concerned that we’re left with corporate philanthropy, a system that enables wealthy individuals to create policy without participating in democracy. Let’s take the Harvard experiment. Its funding list is a who’s who of Silicon Valley: the William and Flora Hewlett Foundation, Bill Gates, the venture capitalist Chris Sacca. Just because the tech industry is enamored of its ability to both disrupt the world and save it doesn’t mean we want it picking the solutions to the greatest problem the world has ever known.

Keutsch said something else to the MIT Technology Review that highlights the disconnect between funders of geoengineering and the people doing the science: “I think better understanding what the risks may be is very important.” Given the quickness with which solar geoengineering could provide some sort of temporary relief to global warming, he was worried that politicians might be tempted to use it, risks be damned. Keutsch isn’t researching geoengineering because he thinks it’s cool but because he thinks it’s dangerous. Like many scientists in this field, he hopes we never use this technology. Some of the technology’s champions, however, are framing a worst-case scenario as the best case. No surprise that those who benefit most from the status quo would sooner risk the entire planet than their positions on it.

Amy Westervelt