These Scientists Plan to Dim the Sunlight

Did you know that Harvard scientists have this controversial plan to dim sunlight? It's been in the news for years, but it's becoming closer to reality as the scientists propose a "June 2021 test flight of a research balloon designed to drop small amounts of chalky dust and observe its effects."

This first flight would not inject the particles; it would only be a dry run of the steerable balloon and instruments needed to study chemical reactions in the stratosphere, the calm, cold layer more than 10 kilometers up. Even so, the project, called the Stratospheric Controlled Perturbation Experiment (SCoPEx), must first win the approval of an independent advisory board, a decision that could come in February 2021.

The need to study the real-world effects of releasing reflective particles is pressing, says David Keith, a Harvard energy and climate scientist and one of SCoPEx’s lead scientists. Solar geoengineering is no substitute for cutting greenhouse gas emissions, he says, but it could ameliorate the worst damage of global warming, such as the extreme heat waves and storms that claim many lives today. “There is a real potential, maybe a significant potential, to reduce the risks of climate change this century—by a lot.”

Inasmuch as there's a great potential for solar geoengineering, there's also a downside.

But research in solar geoengineering has long been taboo, says Faye McNeill, an atmospheric chemist at Columbia University who is unaffiliated with SCoPEx. “We didn’t want it to appear that we were encouraging it.” One fear is that solar geoengineering could be done unilaterally by groups or nations, with unknown effects on plant growth and rainfall patterns. Another worry is that it would encourage a sort of addiction, adding more and more particles to block warming while not addressing the root problem of mounting emissions. But now, with so much warming already locked in, “the urgency of the climate problem has escalated,” McNeill says.