With Mr. Trump pushing the United States, the world’s second-largest emitter after China, away from its mitigation commitments, geoengineering looks even more compelling.

“If the United States starts going backwards or not going forward fast enough in terms of emissions reductions, then more and more people will start talking about these options,” said Mr. Pasztor, a former United Nations assistant secretary general on climate change.

While many of the scholars gathered in Washington expressed misgivings about deploying geoengineering technologies, there was a near-universal consensus on the need to invest more in research — not only into the power to cool the atmosphere but also into the potential side effects on the atmosphere’s chemistry and on weather patterns in different world regions.

While it is known that solar radiation management can cool the atmosphere, fears that field research would look too much like deployment have so far limited research pretty much to computer modeling of its effects and small-scale experiments in the lab.

Critically, the academics noted, the research agenda must include an open, international debate about the governance structures necessary to deploy a technology that, at a stroke, would affect every society and natural system in the world. In other words, geoengineering needs to be addressed not as science fiction, but as a potential part of the future just a few decades down the road.

“Today it is still a taboo, but it is a taboo that is crumbling,” said David Keith, a noted Harvard physicist who was an organizer of the conclave.

Arguments against geoengineering are in some ways akin to those made against genetically modified organisms and so-called Frankenfood. It amounts to messing with nature. But there are more practical causes for concern about the deployment of such a radical technology. How would it affect the ozone in the stratosphere? How would it change patterns of precipitation?