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Opinion Can geoengineering slow climate change? We need research to find out.

The NASA WB-57 after takeoff. (Chelsea Thompson/NOAA/CIRES)
5 min

Gernot Wagner is a climate economist at Columbia Business School and the author of “Geoengineering: The Gamble.

Can solar geoengineering help solve anthropogenic climate change? We don’t know, and we need to start finding out.

Attempting to shield Earth from the sun’s rays in what’s often described as a last-ditch effort to cool average global temperatures is controversial for good reason. It might work and do a lot of good, but there are ample risks. Most importantly, it is no replacement for cutting greenhouse gases. Researchers who study the approach most closely are the first to say just that. Using solar geoengineering as the latest excuse not to slash carbon and other pollution would be a mistake. But research we must.

That’s why it is notable to see first-of-their-kind federal research flights take off from Houston into the stratosphere this week. They’ll only collect baseline data, but that is in part “to inform policy decisions related to … potential of injection of material into the stratosphere to combat global warming.” This is a significant step forward in government-sponsored solar geoengineering science. The emphasis here is on “research.”

It is the opposite to prematurely deploying the technology. That’s what happened in April 2022 when an enterprising and deliberately provocative entrepreneur launched at least two balloons in the Mexican state of Baja California that may have released reflective sulfur particles in the stratosphere, a fact only revealed late last year. Its founder told James Temple of MIT Technology Review: “We joke slash not joke that this is partly a company and partly a cult.” Solar geoengineering research needs neither.

Raising around $750,000 in venture capital to sell “cooling credits” for these balloon flights, as his start-up has done, was a horrible idea. I say that as someone who posited such a scheme as “technically possible” and “economically feasible” in a 2019 paper with geoengineering governance scholar Jesse Reynolds. We argued that it would be only a matter of time before someone somewhere would attempt it.

The outcome was predictable. Mexico has halted all such solar geoengineering attempts. Sadly, that won’t stop this entrepreneur or others elsewhere from attempting similar stunts. Equally sadly, it may well deter legitimate, much-needed research. That’s particularly true in a country and world on edge about spy balloons.

Fortunately, the U.S. National Oceanic and Atmospheric Administration has been pressing ahead with around $10 million each year in “Earth’s radiation budget.” That figure falls short of the $200 million over five years recommended by the National Academies of Sciences, Engineering, and Medicine in a 2021 report, as part of a coordinated federal effort. It is, however, a departure from privately funded programs, including one that I co-founded at Harvard University.

When Harvard’s Solar Geoengineering Research Program launched in 2017 with a budget over $10 million, private philanthropy money seemed to us the only option.

We feared then that courting federal cash would be hopeless and help create what environmentalists call green moral hazards. We could picture the president tweeting: “Found solution to climate change! Told you there was no need to tax carbon!” As far back as 2008, former speaker of the House Newt Gingrich called for the use of solar geoengineering to stop an emissions trading bill.

Which I now see only underlines the need for legitimate, federally funded research, and NOAA’s program is just that. Since 2020, the agency has been flying research balloons into the stratosphere to study particles already there. This week it adds flights with a NASA WB-57 research jet. The 1960s-era B-57 bomber is retrofitted with over a dozen scientific instruments to measure “stratospheric aerosol processes, budget and radiative effects,” hence the project’s name: Sabre.

The most important point: It’s just regular science, including detailed research hypotheses, fancy instruments, years of lead-time, months of subsequent data analysis, and nerdy acronyms. The flights hope to study how sulfate particles behave throughout their life span in the second layer of the atmosphere and how they react with soot and other human and natural elements already there.

Some will say that this research pushes us ever further down the “slippery slope” toward large-scale deployment. In reality, it might do the opposite: lead to more research by showing just how complex and potentially risky a solar geoengineering intervention might be.

It helps that all of this is happening in the context of the global clean-energy race jump-started by passage of the Inflation Reduction Act. It would take a jaded view to believe that a $10 million solar geoengineering research program, itself part of a $3 billion federal climate research program, would detract from hundreds of billions of dollars in investments in cleaner, safer technologies that help cut carbon pollution in the first place.

Yes, it is so late in the climate fight that some solar geoengineering may well be a good idea. We won’t know, unless scientists are able to do the hard work to find out.