The climate clock is ticking. To turn it back, the world is putting its faith in ‘negative-emissions technologies’. These would suck carbon dioxide out of the atmosphere and lock it up for centuries on the land, in the sea or beneath the sea floor. Storing carbon in the oceans sounds promising to some. The oceans are vast, and there could be fewer political trade-offs to deal with than on land.

However, there is a dearth of information is hampering the development of a global framework for regulating geoengineering research, despite more than a decade of debate. Researchers and policymakers need to know which negative-emissions technologies are worth investigating, and which will never work or are too damaging to pursue. The potential benefits and risks of the technologies need to be established before country leaders or companies decide to implement them prematurely.

Philip Boyd, a professor of marine biogeochemistry at the Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia and Chris Vivian, a former national marine adviser at the Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, UK call on advocates of geoengineering, from research to commerce, to build a body of basic scientific evidence within the next three years. This would enable policymakers to decide which methods to rule out and which hold potential. Geoengineering knowledge and regulation must advance in parallel.

Should we Fertilize Oceans or Seed Clouds? No One Knows