I am intrigued with the part of the geoengineering experiment that utilizes calcium carbonate .
"Keith has previously used computer modeling to explore the possibility of using other materials that may have a neutral impact on ozone, including diamond dust and alumina. Late last year, he, Keutsch, and others published a paper that found using calcite, a mineral made up of calcium carbonate, “may cool the planet while simultaneously repairing the ozone layer.”
The balloon tests could provide additional insight into how these chemicals actually interact with precursors to ozone in the real world and offer additional information that could help refine their understanding of solar geoengineering, he says: “You have to go measure things in the real world because nature surprises you.”
Is it time for scientists to begin geoengineering-related experiments in the open air?
Keith stresses that it’s too early to say whether any geoengineering technologies should ever be deployed. But he has argued for years that research should move ahead to better understand their capabilities and dangers, because it’s possible they could significantly reduce the risks of climate change. He stressed that the experiments would have negligible environment impacts, as they will involve no more than a kilogram of materials."
We should keep some perspective on the difference between an experiment and full scale geoengineering implementation . We do on a regular basis shoot rockets into space. I am quite sure those rocket launches inject tons of emissions into the stratosphere. A kilogram of calcium carbonate is harmless in comparison .https://www.technologyreview.com/s/603974/harvard-scientists-moving-ahead-on-plans-for-atmospheric-geoengineering-experiments/