The thing about humans is, for all our faults, we’re actually pretty good at fixing things we know we’ve screwed up. Lead in gasoline? Bad idea—let’s ban lead in gasoline. Running out of oil to make gasoline? Let’s switch to electric vehicles.

Runaway climate change because humanity has taken too long to ditch fossil fuels? That’s … a bit trickier. Because even if the world meets the emissions goals of the Paris Climate Agreement, it may be too late to fix what we’ve done.

So a growing chorus of scientists have been mumbling about geoengineering. Doing things like spraying sulfur in the stratosphere or whitening clouds to bounce light back into space to help cool things down. And last week, Congressman Jerry McNerney joined them, introducing a bill that would ask the National Academies of Science to explore technologies to geoengineer Earth. In two reports, they'd explore research avenues and oversight of that research—that is, if the bill gets past McNerney's colleagues and then the only world leader to shun the Paris Climate Agreement.

To be clear, McNerney would love nothing more than for the US to cut emissions. But the climate situation has become so dire that he thinks geoengineering is now something the US is obligated to explore. Not, like, initiating a full-scale manipulation of the stratosphere next week, but at least looking into the idea. “It's very important that we understand what our tools are,” he says. “What options do we have? How much risk is there?”

The options are few and the risks murky. Take, for instance, sulfur seeding. The idea is to inject sulfur dioxide into the lower stratosphere, where it turns into sulfur aerosol that reflects light back into space. Problem is, just last month researchers released a study showing that if you injected the stuff into the Northern Hemisphere, you might reduce hurricanes in the Atlantic—and kick off a drought in north-central Africa in the process.

At the moment, no scientist is flying around in the stratosphere dumping out sulfur dioxide. They’re working with models and, conveniently enough, studying historical precedent—because the same sort of cooling happens when a massive volcano erupts. In 1912, for instance, an Alaskan volcano popped 30 cubic kilometers of ash and debris into the atmosphere. The next year was the only year on record without a hurricane, which is in keeping with the new models.

Another geoengineering option is called marine cloud brightening, which entails … the brightening of marine clouds. To do this, theoretically you’d spray tiny salt particles from sea water into clouds. When clouds are dark and stormy-looking the droplets are larger. The added salt particles would act as “cloud condensation nuclei” to draw away water from these existing droplets to form new ones, resulting in more smaller droplets. “If the droplets are smaller, there’s more sunlight bouncing off all the surface area and the cloud is lighter and fluffier,” says Kelly Wanser, principal director of the Marine Cloud Brightening Project at the University of Washington. 1

The problem is that when you’re reflecting light away from Earth, you’re drawing heat out of the system. And when you do that you’re potentially reducing evaporation, which of course produces rain. “In general,” Wanser says, “and this kind of shows in the models, these geoengineering techniques are likely to produce a little less precipitation, and that effect is likely to be uneven and may be really hard to predict.”

Which brings us to the question of regionality. One country might decide it wants to tinker with its atmosphere, but that could muck things up for its neighbors, both near and far. And as you might imagine, there’s no treaty on the books that says you can’t geoengineer your neighbors into oblivion. “The current framework for ensuring accountability under international law is pretty thin on what it substantively requires,” says Anna-Maria Hubert, principal investigator at the Geoengineering Research Governance Project. “And whether it could even be enforced is a separate question.” (A reminder that McNerney's bill would task the National Academies of Science with exploring the critical matter of oversight.)