The Canadian scientist behind a controversial attempt to combat climate change by dimming the sunlight reaching the Earth is vowing to keep at it after Sweden’s space agency decided last week to cancel what many critics considered a wildly untenable experiment.

The Stratospheric Controlled Perturbation Experiment (SCoPEx) test this June, led by Harvard University researcher David Keith, “would have involved releasing a tiny amount of reflective material 20 kilometres (12 miles) into the atmosphere, to help researchers better understand how such ‘solar geoengineering’ might help cool the planet,” the Thomson Reuters Foundation reports. “Such technology mimics the cooling effect of volcanic eruptions and could reduce global temperatures—though its potential risks are unclear and it would not address other climate change-related threats, such as ocean acidification.”

But in the end, the publicly-owned Swedish Space Corporation (SSC) stepped away from the experiment. 

“There is no clear international consensus on the appropriateness of this type of research,” the agency said in a statement last Wednesday. “After discussions with Swedish experts and stakeholders, and in agreement with Harvard, SSC has decided not to conduct the planned test flight with a balloon this summer.”

That decision suited a growing roster of alarmed observers just fine.

“We are talking about a technology that could have extreme consequences, that could alter hydrological cycles, disrupt monsoon patterns, and increase droughts,” said Johanna Sandahl, president of The Swedish Society for Nature Conservation, the country’s largest environmental association. “It seems unmanageable and too dangerous to implement.”

Åsa Larsson Blind, vice president of the Saami Council, said technological fixes like solar geoengineering go “completely against what we need to do now—transform to zero-carbon societies in harmony with nature.”

“It shows there is simply no appetite for that technology,” added Lili Fuhr, a geoengineering specialist at Germany’s Heinrich Böll Foundation. “We don’t think it needs further research. We know enough about its dangers.”

Keith, a professor of applied physics at the Harvard School of Engineering and Applied Sciences, called the decision “a setback”, but told Thomson Reuters the test could still be carried out in the United States, though not until next year. “The project said it would use the coming months to try and win over opinion in Sweden and build support for an eventual test,” Thomson Reuters adds.

The Ottawa-based ETC Group published detailed responses from Indigenous partners, all declaring SCoPEx too dangerous to even test, much less implement.

“Solar geoengineering violates the worldview of the Saami people,” Larsson Blind said. “We welcome SSC’s decision to stop the balloon flight planned for Saami lands in Kiruna, but the existential risks of this geoengineering technology disqualify it from ever being advanced—whether here or elsewhere. The false argument that this treacherous technology could be a ‘Plan B’ is deeply dangerous. There is no safe or responsible way to deploy solar geoengineering technologies.”

“This technology is not a solution for mitigating climate change,” agreed Indigenous Environmental Network Executive Director Tom BK Goldtooth, adding that the Saami had never been consulted on the experiment. “It has too many risks that will violate the rights of the Saami Indigenous peoples and the delicate balance of the natural laws of Mother Earth and Father Sky.”

“This is at least the third time that SCoPEx has been halted on Indigenous territory. First in New Mexico, then Arizona, and now Sweden,” noted ETC Group Research Director Jim Thomas. “Each time, geoengineers promise to ‘consult’ better, deliberately missing the point that consultation does not equal consent. When communities and Indigenous people say no to planet-altering schemes being launched from their territories, it is disrespectful to mishear that as ‘needing more consultation’. No means no.”

The news and the intense pushback came just a week after the U.S. National Academy of Sciences, Engineering and Medicine concluded the climate crisis is dire enough to warrant experimentation with a technology as extreme as solar geoengineering. 

“Supporting research into those possibilities shouldn’t be equated with actually implementing them, the NAS committee members involved with the report emphasized, adding that such studies should not detract from the need to cut greenhouse gas emissions,” Inside Climate News reports. “And scientists ‘need to be open to terminating’ geoengineering research if findings indicate that such manipulations of the atmosphere would carry undue risk of dangerous consequences, they said.”

But those are precisely the fundamental objections critics have raised in response to the prospect of even testing solar geoengineering—that hyped-up hopes of a high-tech solution would indeed delay decarbonization options that are already ready for prime time, that enough (or too much) is already known about the dangers posed by solar geoengineering, and that the technique could not be temporary once the Earth’s modified cycles became dependent on it.

“It’s kind of surreal to even be talking about this,” NAS committee member Ambuj Sagar, who studies science and technology policy at the Indian Institute of Technology, told Inside Climate. “You can’t be doing climate policy without thinking about geoengineering, and the more you get into it, the more complex it is. It raises all kinds of issues with international politics and governance.”

When those governance issues were last addressed in a United Nations forum, it didn’t go well.