Featured image: Critics say that strategies to artificially shield Earth from sunlight are a distraction from carbon-cutting. Credit: Tui De Roy/Nature Picture Library

Climate engineering has long been seen as the rogue approach to global warming. Public opposition has stymied field experiments of this strategy, which aims to artificially cool the Earth. Dozens of countries have called for an end to the development of climate-engineering approaches. Critics say that such projects could have disastrous unintended consequences.

Even so, some scientists say that climate-engineering methods, such as lobbing particles into the atmosphere to reflect sunlight, might provide humanity with an eleventh-hour option to avoid global tipping points. For this method to be a viable path forwards, large knowledge gaps must be filled.

“We need to know enough about climate intervention that, should it ever be deployed, we know how to do it in a way that has the maximal benefits and the minimal harm,” says Jessica Gurevitch, an ecologist at Purdue University in West Lafayette, Indiana, who emphasizes that climate engineering should not replace cutting carbon emissions.

At the American Geophysical Union (AGU) meeting in Washington DC, in December, scientists discussed the research questions to be answered and the policies that must be put in place for climate engineering to be properly vetted. Here’s what scientists at the meeting and elsewhere say needs to happen.