Startup says it can cool the planet for $10B a year; scientists push back

An Israeli-US startup says it can cool the planet for $10 billion a year by spraying tiny particles into the atmosphere to reflect sunlight — but scientists warn the technology could destabilize the global climate system in ways no experiment can predict.

Stardust Solutions, founded in 2023 by two former Israeli government nuclear physicists, is among the most prominent companies pursuing solar geoengineering, a controversial approach to artificially lowering global temperatures by dimming the sun. The company has raised $75 million from investors, making it the best-funded venture in the space, according to CNN.cnn

The Technology

The concept mimics nature. When Mount Pinatubo erupted in the Philippines in 1991, it ejected enough sulfur dioxide into the atmosphere to cool the planet by roughly 0.5 degrees Celsius for over a year. Rather than sulfur dioxide, which can contribute to acid rain and ozone depletion, Stardust has developed two alternative particle types: one made of amorphous silica, a common food additive, and another with a calcium carbonate core coated in silica.wtop+1

CEO Yanai Yedvab told CNN that every million tons of particles deployed would produce roughly 0.5 degrees Celsius of cooling, at a cost of about $10 billion per deployment. The particles would need to be replenished annually as they fall out of the atmosphere. Earlier this year, the company published six academic papers — still awaiting peer review — detailing its particle designs and dispersal systems.politico+2

Red Flags From Scientists

Researchers have raised pointed objections. Raymond Pierrehumbert, a professor of planetary physics at the University of Oxford, said that "when the whole world is at stake, satisfying the needs of venture capitalists for profits should not enter at all into decisions about what, if anything, should be deployed".wtop

David Keith, a professor of geophysical sciences at the University of Chicago and a leading researcher in the field, said Stardust is "greatly overclaiming to say that they're confident the risks [of their particles] are lower than with sulfur". Among the concerns is the "hitchhiker hypothesis" — the possibility that particles could absorb harmful metals or other substances in the atmosphere that people could later inhale.mezha+1

Perhaps most alarming to critics is the prospect of "termination shock." If solar geoengineering were deployed and then abruptly halted, suppressed warming could emerge rapidly within years, potentially causing a climate crisis far worse than gradual warming.wtop

Governance and Ethics

Stardust has so far limited its work to laboratory tests. The company says it hopes to begin outdoor experiments in the coming years but only under direct government supervision. Still, Sarah Doherty, an associate professor of atmospheric sciences at the University of Washington, said "the current science does not support making financial bets on, or driving society toward, specific approaches".wtop

The question of who decides whether, when, and how such technology is deployed remains unresolved. "I worry that decisions about if, when, and how to deploy solar engineering will not be made by poor countries but rather by rich countries and private investors," said Chukwumerije Okereke, a professor in global governance at the University of Bristol.wtop