Supercomputer Will Help Decide whether to Block the Sun

A new supercomputer is helping climate scientists determine whether injecting human-made, sun-blocking aerosols into the stratosphere would also alter thunderstorms and rainfall

A new supercomputer funded by the federal government will help researchers understand solar geoengineering. Credit: Photo and Co/Getty Images

CLIMATEWIRE | A new supercomputer for climate research will help scientists study the effects of solar geoengineering, a controversial idea for cooling the planet by redirecting the sun’s rays.

The machine, named Derecho, began operating this month at the National Center for Atmospheric Research 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.

Because Derecho is 3 ½ times faster than the previous NCAR supercomputer, her team can run more detailed models to show how regional changes to rainfall can be caused by the release of aerosols, adding to scientists’ understanding of the risks from solar geoengineering, Rasmussen said. The machine will also be used to study other issues related to climate change.

“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 announcement from NCAR comes after the Biden administration released a report Friday that offered measured support for researching solar geoengineering as a way to slow the rise of global temperatures. NCAR is funded largely through the National Science Foundation, an independent agency of the federal government.

The White House report follows an open letter by more than 60 leading scientists calling for more research into what is often called solar radiation modification, one method of altering Earth’s natural systems to fight climate change. European Union policymakers also issued a statement last week calling for an international assessment of the risks related to geoengineering.

“These technologies introduce new risks to people and ecosystems, while they could also increase power imbalances between nations, spark conflicts and raises a myriad of ethical, legal, governance and political issues,” the E.U. statement said.

Critics of geoengineering say using aerosols and other substances to reflect sunlight away from Earth could lead to unknown, disruptive weather patterns. They also contend that solar geoengineering could result in a global dependency, because temperatures could abruptly rise if the process is stopped.

The new supercomputer will allow scientists to build and run intricate models to assess the risks tied to geoengineering, Rasmussen said, adding that slight changes to the atmosphere’s composition could lead to large impacts not just on rainfall patterns — her area of study — but on entire ecosystems, including human communities.

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.”