Governments and private donors have opened their pockets in advance of that failure. This summer, China’s national Ministry of Science and Technology announced it will fund a 15-person, $3 million geoengineering research program at Beijing Normal University. It will join several government-funded teams working on the same problem in Germany as well.

This fall, Harvard University will also launch its own solar geoengineering research with $7.5 million in funding from private sources. Its leaders hope to eventually amass a budget of $20 million.

So the conference, organized by Gordon Research Conferences, was well-timed. It is thought to be the largest gathering of geoengineering scientists ever assembled, and its participants included almost every senior researcher in the field. It was held under the Chatham House rule, which proscribed attendees from disclosing who said what, but its agenda and attendees list are available online.

Leaders and participants described a strategy-focused gathering that allowed the rapidly growing field to settle on common research questions.

“We had a really, really good conference,” said Trude Storelvmo, a professor of atmospheric chemistry at Yale University and one of the vice chairs of the conference. The attendees included physicists, chemists, biologists, economists and social scientists, reflecting the degree to which the problem “touches a lot of disciplines.”

Nearly everyone involved described their work as a way to find a stopgap to the looming problem of climate mitigation.

“We all agree that climate change is real and that the solution is to reduce the emissions of the gases that cause global warming,” said Alan Robock, a professor of atmospheric chemistry at Rutgers University and one of the co-chairs of the Maine meeting. “The Paris Agreement was a good start, but those pledges aren’t enough, and we have to reduce more. Even then it [won’t be] fast enough. So what we’re looking at is: If global warming is so dangerous, could we shave off a little warming while we continue to mitigate greenhouse gases?”

There are several ways of holding off that warmth. They all involve bouncing sunlight back into space before it penetrates too far into the lower atmosphere. Over the past decade, scientists have discussed some different ways to do this: by brightening clouds over the ocean; by pushing cirrus clouds to form in the high atmosphere; or by spraying a reflective gas into the sky at high altitudes, mimicking the effect of a large volcanic eruption.

Last month’s meeting arrived at the consensus that this final technique—called stratospheric aerosol injection—is the best bet going forward. Researchers don’t see a technological impediment to developing seeding tools, seeing the few remaining problems as within the capability of any large aerospace company. There are plenty of natural precedents for stratospheric aerosols, too—volcanoes have gone off hundreds of time during human history—and they see it as the most reversible and easy to model.