The whole endeavor, Smith said, is far cheaper and simpler than he initially imagined. There are no real barriers, he said. The total cost of the project? A measly $3.5 billion, he estimated.

“I think it’s bad news how cheap this is,” Smith told a small group last month in a conference room at Harvard’s Center for the Environment. For that kind of money, Smith argued, it’s possible that any rogue nation, organization or individual could start experimenting with the climate.

The impacts of geoengineering on the global scale are unknown, in part because no massive geoengineering project has been undertaken ― apart from human-induced climate change. But models are potentially troubling. Some suggest geoengineering will disrupt rainfall worldwide and damage the earth’s protective ozone layer . A Rutgers University study published in January suggested that suddenly stopping a large geoengineering project, once it has started, could lead to rapid warming, pushing species into extinction and accelerating climate change.

As global temperatures continue to rise, however, some researchers say geoengineering shouldn’t be dismissed. Helene Muri, a researcher at the University of Oslo geosciences department, said it shows promise as a way to reduce harm from climate change, but it is not ready. “We need to know more about the risks involved before we, if we can ever, deem it safe to use,” she said. “Solar geoengineering is in any case not a substitute for cutting CO2 emissions.”

Yet, with every year and climate conference that passes, a global-scale geoengineering project becomes more and more feasible. There’s virtually no regulation stopping a country or individual from trying this, Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University, told me. In fact, from a legal perspective, it’s easier to seed the stratosphere than get a permit to remodel your home, he added.

“I think there is such a large chance that someone will try geoengineering that it really needs to be governed,“ said Gerrard. That’s why, together with Tracy Hester at the University of Houston Law Center, he just published a book, Climate Engineering and the Law, intended to help policymakers, technologists and lawyers better understand current regulations and science underlying big-scale geoengineering projects.

The question is when such a project might be attempted, and by who? Gerrard imagines a scenario in which some country, in the wake of a ruinous climate disaster, sees no other choice.

“One could imagine that if some catastrophic [climate] event were to occur in India, and they had a real concern that another one could happen, they would want to, on their own, launch a geoengineering effort to protect themselves against the next one. That’s an entirely plausible scenario,” said Gerrard. That’s why global agreement on governance is needed, he said, followed by country-by-country laws on geoengineering. Failing to legislate, he warned, could result in war because of the harmful climatic consequences of one country’s hasty project.

However imminent a large-scale geoengineering project may be, what’s complicating serious debate on the matter is the narrative perpetuated, in the media and online, that geoengineering is a way to “solve,” “fix” or “stop” climate change.

This trend has persisted for over a decade. For a 2014 paper published in Environmental Humanities, researchers in Sweden analyzed hundreds of news articles and found that one of the most prevalent storylines around geoengineering was “the notion that pure technology is the only possible solution and that it is an adequate substitute for politics.”

This may be partly because of the way scientists angle their research. “In these days of click-baits and social media likes, it is perhaps tempting to pitch the extreme case scenarios,” said Muri. “I think it is our responsibility as scientists to present our findings in a careful and nuanced way.”