Plans to test a technique that would cool the planet by blocking sunlight are one step closer to reality. Harvard University in Cambridge, Massachusetts, has created an external advisory panel to examine the potential ethical, environmental and geopolitical impacts of this geoengineering project , which has been developed by the university’s researchers.

Known as the Stratospheric Controlled Perturbation Experiment (SCoPEx), the project would involve the release of calcium carbonate particles from a steerable balloon some 20 kilometres above the southwestern United States.

Louise Bedsworth, executive director of the California Strategic Growth Council, a state agency that promotes sustainability and economic prosperity, will lead the Harvard advisory panel, the university said on 29 July. The other seven members include Earth-science researchers and specialists in environmental and climate law and policy.

Harvard said in 2017 that it would create a panel of external experts to oversee SCoPEX in response to concerns from scientists and environmentalists that geoengineering could change weather patterns or harm crops.

SCoPEx scientists, led by atmospheric chemist Frank Keutsch and physicist David Keith, hope to release small plumes of about 100 grams of calcium carbonate into the upper atmosphere and then study how the particles disperse. The scientists will also watch for changes in atmospheric chemistry and how light scatters.

The SCoPEx team said last year that the project could be ready to launch as early as the first half of 2019, if an advisory panel were in place and ready with recommendations. But Keith declined to speculate on how soon the experiment might fly now that Harvard has created the panel.