A controversial experiment to artificially cool Earth was canceled

Large gates to the entrance of Harvard’s campus. The left side of the gate is open, and the other side is closed. — *Cambridge, MA – January 24: Gated entrance on the campus of Harvard University.* | Photo: Getty Images

After years of legwork, Harvard researchers canceled plans to test a controversial theory for cooling the planet by sending sunlight-reflecting particles up into the atmosphere. Now, members of an independent advisory committee tasked with addressing ethics and safety concerns are sharing what they learned from the ill-fated project.

A policy analysis published in the journal Science on Friday highlights how important it is to talk to people on the ground before launching an experiment, especially one tied to potentially planet-altering consequences. The paper echoes recent calls to get policies in place to protect against any unintended side effects.

Until pretty recently, the thought of reflecting sunlight back into space to combat…