Trapped inside a long glass tube in a ground-floor lab at Harvard University is a miniature copy of the stratosphere.

When I visited Frank Keutsch in the fall of 2019, he walked me down to the lab, where the tube, wrapped in gray insulation, ran the length of a bench in the back corner. By filling it with the right combination of gases, at particular temperatures and pressures, Keutsch and his colleagues had simulated the conditions some 20 kilometers above Earth’s surface.

In testing how various chemicals react in this rarefied air, the team hoped to conduct a crude test of a controversial scheme known as solar geoengineering, which aims to counter climate change by spraying tiny particles into the stratosphere to reflect more of the sun’s heat back into space.

But is what’s in that tube “really what the stratosphere is like?” asks Keutsch, a professor of engineering, chemistry, and atmospheric science, as he gestured toward it. “That’s the question. We try to think of everything, but I would argue you never quite know.”

That’s why he and fellow researchers, including Harvard climate scientist David Keith, want to move their experiments out of their toy stratosphere and up into the real one. They hope to conduct a series of scientific balloon flights, the first of which could launch from the Esrange Space Center in Kiruna, Sweden, as soon as this summer.

I seriously hope we’ll never get in a situation where this actually has to be done, because I still think this is a very scary concept and something will go wrong.

Frank Keutsch, principal investigator of SCoPEx

The initial flight will simply evaluate whether the aircraft’s equipment and software work properly in the stratosphere, where temperatures can plunge below 50 ˚C and the pressure ranges from one tenth to one thousandth the amount at sea level. But in subsequent launches, the researchers hope to release small amounts of the sorts of particles that could scatter sunlight.

In a world that’s cutting carbon dioxide emissions too slowly to prevent catastrophic climate change, solar geoengineering might buy some time. But doing it on a large scale could mean messing with planet-wide weather patterns. The effects are unpredictable; in some places, they might even be disastrous.

In the coming weeks, therefore, an independent advisory committee that is reviewing the legal, ethical, and environmental issues surrounding the project is expected to determine whether the research group should proceed with the first flight. The committee will also have to rule before any flights that actually release materials, and determine what steps the research team should or must take to engage with the public and regulators.

If those launches are approved—and that’s still a big if—they will be the first geoengineering experiments in the stratosphere. But before the balloons have even left the ground, they’re already drawing

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By: Emily Luong
Title: A first-of-its-kind geoengineering experiment is about to take its first step
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Published Date: Fri, 19 Feb 2021 14:36:51 +0000

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