Bill Gates says he would support deploying artificial cooling technologies to lower global temperatures — but only if the planet hits so-called climate tipping points.
Why it matters: The Microsoft co-founder and philanthropist is a major funder of research into this controversial technology, and his comments in a recent interview with Axios are among his most expansive yet.
- Activity by startups has sparked a wave of media attention to the tech, which is known as geoengineering. Coverage includes The New Yorker, The Atlantic and Politico magazine during November alone.
The big picture: Solar radiation management — reflecting more of the sun's energy back into space — is a subset of geoengineering that's shifting from fringe science and conspiracy theory into mainstream policy debate.
- The idea could help blunt extreme weather, but its risks remain uncertain and likely significant.
How it works: Solar radiation management, or solar geoengineering, aims to cool the planet by reflecting sunlight.
- The most-discussed method involves injecting sulfuric-acid particles into the upper atmosphere, mimicking the cooling effect of volcanic eruptions.
Driving the news: Gates' comments, made during an interview last month at Caltech, are significant because he makes a distinction between what's become a more common position — supporting research into geoengineering — versus actually deploying it.
Zoom out: In the interview, Gates said the world is largely on track to avoid the worst climate impacts thanks to rising clean-energy deployment.
- But he emphasized there's still an outlier chance of especially dire consequences driven in part by tipping points — scenarios in which warming triggers reinforcing feedbacks, or secondary effects, which accelerate climate change.
- You "would then need to reach for some other type of intervention," Gates said.
When asked whether that meant geoengineering — and whether he would support its deployment in such a scenario — Gates replied: "Yes, I've been a funder of trying to understand geoengineering."
- Much of his funding isn't publicly disclosed, but what is known includes past support for Harvard University's solar geoengineering program.
Context: Gates stressed the difference between supporting research and advocating deployment.
- "No way am I pushing the world in that direction," he said, before adding that having knowledge about it could be "quite valuable."
Friction point: "There are two big arguments against it, which are both legitimate and need to be considered," Gates said.
- Political: Relying on solar geoengineering could undermine efforts to cut fossil-fuel use. "That's terrible if that slows that down," he said.
- Scientific: Researchers need a clear understanding of how injected particles would affect communities, including risks of altered rainfall or drought.
The intrigue: Conspiracy theorists — who have targeted Gates for years — have focused on geoengineering as well, fueling political backlash.
- Such theories are a major driver of state-level bans and prompted Trump administration investigations.
Catch up fast: Israel-based Stardust Solutions disclosed a $60 million fundraising round in October.
- That raised alarms about whether private companies should be able to act independently on such a consequential technology.
Zoom out: At this year's United Nations climate summit in Brazil, leaders acknowledged for the first time that the world is on track to exceed temperature thresholds associated with especially severe impacts.
- Those conditions could trigger the kinds of tipping points under which Gates said he could support deploying geoengineering.
- Scientists say such scenarios are likely decades away, even as extreme weather worsens today.
The bottom line: "In some ways, that's the least confrontational framing" on geoengineering, said Zeke Hausfather, a climate scientist at Berkeley Earth, about Gates' comments.
- "It doesn't remove all the thorny questions, but it's probably the most defensible approach to take today."
Disclosure: Amy Harder is the former founding executive editor of Cipher News, an independent news outlet supported by Bill Gates' climate and energy initiative Breakthrough Energy.
Sign up here for Axios' Future of Energy newsletter.
