Study the Risks of Sun-Blocking Aerosols, Say 60 Scientists, the US, the EU, and One Supercomputer

Nine days ago the U.S. government released a report on the advantages of studying “scientific and societal implications” of “solar radiation modification” (or SRM) to explore its possible “risks and benefits…as a component of climate policy.”

The report’s executive summary seems to concede the technique would “negate (explicitly offset) all current or future impacts of climate change” — but would also introduce “an additional change” to “the existing, complex climate system, with ramifications which are not now well understood.” Or, as Politico puts it, “The White House cautiously endorsed the idea of studying how to block sunlight from hitting Earth’s surface as a way to limit global warming in a congressionally mandated report that could help bring efforts once confined to science fiction into the realm of legitimate debate.”

But again, the report endorsed the idea of studying it — to further understand the risks, and also help prepare for “possible deployment of SRM by other public or private actors.” Politico emphasized how this report “added a degree of skepticism by noting that Congress has ordered the review, and the administration said it does not signal any new policy decisions related to a process that is sometimes referred to — or derided as — geoengineering.”

“Climate change is already having profound effects on the physical and natural world, and on human well-being, and these effects will only grow as greenhouse gas concentrations increase and warming continues,” the report said. “Understanding these impacts is crucial to enable informed decisions around a possible role for SRM in addressing human hardships associated with climate change…”

The White House said that any potential research on solar radiation modification should be undertaken with “appropriate international cooperation.”
It’s not just the U.S. making official statements. Their report was released “the same week that European Union leaders opened the door to international discussions of solar radiation modification,” according to Politico’s report:

Policymakers in the European Union have signaled a willingness to begin international discussions of whether and how humanity could limit heating from the sun. “Guided by the precautionary principle, the EU will support international efforts to assess comprehensively the risks and uncertainties of climate interventions, including solar radiation modification and promote discussions on a potential international framework for its governance, including research related aspects,” the European Parliament and European Council said in a joint communication.

And it also “follows an open letter by more than 60 leading scientists calling for more research,” reports Scientific American. They also note a new supercomputer helping climate scientists model the effects of injecting human-made, sun-blocking aerosols into the stratosphere:
The machine, named Derecho, began operating this month at the National Center for Atmospheric Research (NCAR) and will allow scientists to run more detailed weather models for research on solar geoengineering, said Kristen Rasmussen, a climate scientist at Colorado State University who is studying how human-made aerosols, which can be used to deflect sunlight, could affect rainfall patterns… “To understand specific impacts on thunderstorms, we require the use of very high-resolution models that can be run for many, many years,” Rasmussen said in an interview. “This faster supercomputer will enable more simulations at longer time frames and at higher resolution than we can currently support…”

The National Academies of Sciences, Engineering and Medicine released a report in 2021 urging scientists to study the impacts of geoengineering, which Rasmussen described as a last resort to address climate change.

“We need to be very cautious,” she said. “I am not advocating in any way to move forward on any of these types of mitigation efforts. The best thing to do is to stop fossil fuel emissions as much as we can.”