The idea behind solar geoengineering is pretty simple. What if we could reflect more of the sun’s energy back into space and thereby reduce the buildup of heat in the atmosphere, sort of like putting mirrors on a greenhouse.

Last week the National Academies of Sciences, Engineering, and Medicine released a new report on the topic titled “Reflecting Sunlight Recommendations for Solar Geoengineering Research and Research Governance.” The report is lengthy but the bottom line is that it supports spending $100 million on research into the topic.

But there is a lot of pushback to the idea of solar geoengineering, not because people think it might not work but because they think it might. And that doesn’t sit well with some activists who think successful efforts could reduce the impetus to reduce carbon output around the globe. That’s why the third paragraph of the NY Times story about the new report is devoted to pushing back on the idea that it’s an alternative to decarbonization.

“Solar geoengineering is not a substitute for decarbonizing,” said Chris Field, director of the Woods Institute for the Environment at Stanford University and head of the committee that produced the report, referring to the need to emit less carbon dioxide and other greenhouse gases into the atmosphere. Still, he said, technology to reflect sunlight “deserves substantial funding, and it should be researched as rapidly and effectively as possible.”

The report acknowledged the risks that have made geoengineering one of the most contentious issues in climate policy. Those risks include upsetting regional weather patterns in potentially devastating ways, for example by changing the behavior of the monsoon in South Asia; relaxing public pressure to reduce greenhouse gas emissions; and even creating an “unacceptable risk of catastrophically rapid warming” if governments started reflecting sunlight for a period of time, and then later stopped.

On the domestic front, there has been some bipartisan support for solar geoengineering but also pushback from Bernie Sanders:

Solar geoengineering has bipartisan support in Congress, which in late 2019 gave the National Oceanic and Atmospheric Administration $4 million to research the technology.

“America needs to be on the cutting edge of climate research,” Representative John Curtis, Republican of Utah, said in a statement. “More knowledge is always better.”

The calculation could be more difficult for President Biden, who has tried to gain the support of the party’s progressive wing, some of whom are skeptical about geoengineering. Senator Bernie Sanders of Vermont has called it a “false solution,” grouping it with nuclear power or capturing carbon dioxide and burying it underground.

Last December, Harvard scientists got permission from the Swedish Space Corporation to run an experiment that would involve maneuvering a weather balloon in preparation for a small scale solar geoengineering test sometime later.

The unmanned flight had originally been planned for the United States but was moved, partly because of U.S. restrictions caused by coronavirus.

The flight, which requires approval from a Harvard project advisory committee, will test how to manoeuvre the balloon and check communications equipment and other systems. It would not release any particles into the stratosphere.

Still, if successful, it could be a step towards an experiment, perhaps in the autumn of 2021 or spring of 2022, to release a tiny amount – up to 2 kg – of non-toxic calcium carbonate dust into the atmosphere, Keith said.

But today New Scientist is reporting the initial test has been put off until next year:

A trailblazing experiment to launch a balloon into the stratosphere from Sweden for a solar geoengineering experiment has been suspended and delayed until 2022 to give more time for engagement with the Swedish public.

The decision by an independent advisory committee is a major setback to the Harvard University experiment, known as SCoPEx.

Was their an outcry from Swedes about this? I’m not sure as I can’t read the rest of the New Scientist story without a subscription.

I once read a science fiction novel about a solar geoengineering scheme gone wrong. The entire planet was nearly destroyed by it and the main characters had to resort to cannibalism at one point. I suspect that’s the kind of thing some people are worried about. But the Harvard experiment was very small scale and no threat to anyone. Resistance to carrying it out is a lot like resistance to reopening schools. It has no foundation in any real likelihood of danger to anyone. It’s just putting politics ahead of science at the expense of children.

Here’s a story from 2019 on the history of solar geoengineering and Harvard’s attempts to study it.