A New Generation of Climate Scientists Warm Up to Solar Geoengineering

Yashas Raj and Jake Chapman are hunkered down in a basement laboratory at the University of Cambridge’s Department of Engineering—tinkering with a handheld nozzle they hope will one day be capable of shooting trillions of microscopic water droplets into the sky every second to brighten clouds over the Arctic Ocean. Boosting cloud reflectivity by adding the mist, they say, would cut the amount of sunlight reaching the water’s surface and slow the melting of Arctic sea ice. 

The two Ph.D. students spend much of their time here in the Seawater Lab, mulling over revolutionary technologies that could curb Earth’s warming trajectory. Their work has drawn contempt from some campus peers who denounce such research aimed at manipulating the world’s climate over fears of unforeseen environmental consequences.

But such criticism has faded into background noise since the U.K. government last year allocated millions of dollars in funding to investigate climate geoengineering. It marked the first time a state funding body had invested significant money in geoengineering research, mainstreaming the once-taboo field and offering some validation to young students.  

Raj and Chapman are part of a growing wave of Gen Z scientists and engineers across the world pursuing higher education in climate geoengineering, grasping for a feeling of agency as they inherit the woes wrought by older generations. “It’s daunting. We’re just 24-year-olds, and the engineering is going to be done by us,” said Raj, originally from Boston, now 25. “We have to build something and test it in the real world.”

The U.K.’s Advanced Research and Invention Agency (ARIA) has allotted 56.8 million British pounds ($76 million) for 21 research teams at global institutions to study climate geoengineering. Notably, nearly half of the ARIA funding will support small-scale field trials—the most contentious area of geoengineering research—to be rolled out over the next three years. 

The public money, including another 10 million pounds ($13.4 million) from the U.K.’s Natural Environment Research Council, provides a heavy counterweight to controversial private startups, including the U.S. and Israeli-based Stardust Solutions and California’s Make Sunsets. These companies are working to commercialize stratospheric aerosol injection, a geoengineering technique that involves releasing reflective particles into the upper atmosphere to deflect some of the sun’s heat away from Earth. 

Cambridge’s Centre for Climate Repair, housed in the same building where Stephen Hawking developed his theories on radiation, was first established in 2019. Over the past six years, the university has supported 19 Ph.D. students and 16 postdoctoral researchers investigating interventions such as sea curtains that could shield melting glaciers in Antarctica; thickening sea ice in the Canadian Arctic by pumping up seawater from under the ice; and brightening clouds over Australia’s Great Barrier Reef and Arctic waters to reduce incoming solar radiation. The centre’s funding comes from the university, government grants and philanthropic foundations. 

“Over the last year, things have changed a lot,” said engineer Shaun Fitzgerald, director of the Centre. “We haven’t had that government financial support before. It’s a signal, in a way. It’s not just firebrand, wacky people trying stuff. If a government research agency says, ‘Actually, we think these are sensible questions,’ then it helps to just normalize the conversation.” 

Other academic institutions, too, have launched climate geoengineering initiatives, incorporating the niche field into curricula. Harvard University introduced its Solar Geoengineering Research Program in 2017 to reduce scientific uncertainties about geoengineering. In 2023, the University of Chicago established the Climate Systems Engineering Initiative as part of a broader push to bolster education on possible climate interventions, with $6 million in funding for research projects.

While academics can apply for external grants to support their research, “the difference now is that there are some places where universities—and maybe the University of Chicago is the most important single place—are actually putting up their own money and starting real programs themselves,” said geophysicist David Keith, the founding director of the Chicago initiative who previously researched geoengineering at Harvard. 

Yet some scientists have pushed back against government and academic support for what they see as risky, moonshot ideas. Geoengineering “offers the sense that there is a solution other than decarbonizing, but there isn’t one,” said Martin Siegert, a glaciologist at the University of Exeter in the U.K. who is opposed to geoengineering. 

The alternative to runaway climate warming, geoengineering research proponents say, is even more dangerous. The U.K. government has cited Earth’s rapid trajectory toward dangerous tipping points—such as the breakdown of global ocean circulation patterns or the transition of the world’s forests into dry savannahs—as the impetus for exploring climate cooling approaches that might avert such crises. 

Raj said that feeling of helplessness and the failure of governments to address climate change through policy compelled him to pursue a career in geoengineering. “We’re on this speeding train to a cliffside, and we’re proposing slowing down by minute fractions,” he said. “We need to stop it—like now.” 

Is the Academic Approach Safer?

Peter Irvine was perhaps one of the earliest students of geoengineering. Back in 2008, armed with a master’s degree in physics, he first stumbled across a newspaper article about climate geoengineering. That, he said, inspired him to pursue a Ph.D. focused on solar geoengineering.

“I think I had like the third one in existence,” he said of his doctorate in Climate Science, which he graduated with from the University of Bristol after completing his 2012 thesis entitled “Climatic effects of solar radiation management geoengineering.” 

Since then, Irvine said global interest in geoengineering has at times surged and then fallen away. But after 2020, the field rapidly expanded alongside a broader recognition that world leaders have failed to rein in climate-warming emissions to keep the planet from surpassing 1.5 degrees Celsius of warming. Today, Irvine works as a research assistant professor at the University of Chicago and as editorial director of the nonprofit SRM360, a group dedicated to informing the public and policymakers about solar geoengineering. 

No university yet offers a formal degree program in geoengineering. Rather, students pursue related fields—engineering, climate and atmospheric sciences, social governance and ethics—with a focus on solar radiation modification. “There’s not a doctoral program right now, but that is an aspiration,” said Keith at the University of Chicago. Its initiative currently has two full-time faculty members, three assistant professors and six postdoctoral research fellows. 

“Academia is often characterized by caution, reluctance, being quiet,” Irvine said. But the academic approach to solar geoengineering research is pivotal, scientists said, because university researchers are investigating pertinent questions about the feasibility and safety of geoengineering methods, rather than advocating for their deployment or use to satisfy investors. 

The startup Make Sunsets, for example, raised more than $1 million from investors and sold $100,000 in cooling credits to customers on the premise of releasing 160 balloons containing sulfur dioxide into the atmosphere. The company’s unauthorized balloon deployments in Baja California, however, led the Mexican government to ban solar geoengineering experiments in the country. Stardust Solutions, meanwhile, announced last year it had raised $60 million in venture capital. As reported by MIT Technology Review, its investor materials include a roadmap to initiate large-scale tests by 2030 and global deployment by 2035, a timeline many climate scientists deem reckless.

“Make Sunsets has courted media attention,” Irvine said. “We’re not trying to sell these ideas to people. We’re just trying to let people know what is going on so they can make their own informed judgments.” 

Moreover, the academic approach often centers on researchers in the Global South investigating whether such interventions could have adverse effects on developing countries that are already disproportionately burdened by global warming. 

Trisha Patel, 28, is from Johannesburg and received her master’s in climate change and sustainable development from the University of Cape Town. Her dissertation explored how stratospheric aerosol injection could impact rainfall and temperature extremes in South Africa, and the potential to disrupt agricultural production and water security for vulnerable communities. 

“I see SRM research as a moral responsibility,” said Patel, who now works with the African Climate and Development Initiative researching geoengineering. “We owe it to ourselves, but also to future generations, to at the very least understand all the possible tools and risks and potential benefits before we might be in a scenario where we would need to make a massive decision under pressure or in a short time.” 

Patel said that she felt discouraged by efforts to address climate change through United Nations processes. Last year, the United Nations Environment Programme said it was exploring climate engineering due to “growing concerns about the lack of global efforts to cut emissions.” 

“There’s just a sense of frustration,” Patel said. “This is a massive problem that younger generations and future generations have been [left] with.” 

Career Concerns

The growth of climate geoengineering research within academia is not without pushback. Last September, Siegert and more than 40 other researchers co-authored a paper in the journal Frontiers in Science dismissing Arctic and Antarctic geoengineering ideas—which include several of the projects being investigated at the University of Cambridge— as “dangerous.” 

The paper dug into the feasibility, cost and unintended consequences of five prominent geoengineering concepts in the polar regions. The loudest criticisms of climate geoengineering, however, have traditionally been that such interventions distract from efforts to cut climate-warming emissions and encourage the continued burning of fossil fuels. 

Siegert explained his main concern with university programs is that senior scientists “might inadvertently be supporting early career scientists, taking them on, and creating a generation thinking that they can do it.”

“It’s really dangerous,” he said. “And I think it’s actually totally unfair of senior scientists. It is almost like using younger scientists, pushing them into this area, giving them the motivation and ideas.” From a career perspective, Siegert dismissed geoengineering as a “non-starter,” arguing students will struggle to find jobs in the field.

Irvine said the 2025 paper, alongside a broader push for a non-use agreement for sun dimming experiments, was likely to foment a chilling effect for students interested in postgraduate studies in geoengineering. “I had a student say to me, ‘I’m worried about doing a PhD on this topic because I worry I won’t have a career. Everyone at the top of my field is saying this is a dead end.’” 

The University of Chicago’s Keith, however, said that viewpoint may eventually die out. “There is a real generational difference. Younger people seem much more open to research on [geoengineering]. Lots of them have wildly different views, as they should. But I don’t see that they have a prejudged answer.”