Is it time to take sun dimming tech seriously? Experts disagree.

As scientists warn of irreversible climate damage, proponents say solar geoengineering technology needs to mature. Critics say it is risky, distracts from the task of decarbonisation and requires an impossible degree of global coordination.

wind turbines at sunrise
Wind turbines at sunrise in Biedesheim, Germany. Image: Karsten Würst, Unsplash

When Mount Pinatubo erupted in 2001, so much sulphur was blown into the sky that it blanketed much of the world, dimming the sun’s rays and causing temperatures to drop 0.6 degrees Celsius below average for 15 months.

Scientists have long been trying to find out if humans scattering similar particles high into the atmosphere, in a more controlled process generally termed solar geoengineering, could help to contain global warming.

The stakes seem ever higher, with the latest report by the Intergovernmental Panel for Climate Change (IPCC) warning that global warming, unless rapidly halted, will result in irreversible changes to human and natural systems, and immense suffering for humanity.

That makes solar geoengineering, seen by the scientific community as a last-ditch option that involves dimming the sun instead of reducing greenhouse gases, a more appealing tool to use in the fight against climate change.

Or, any efforts to develop the nascent technology should be halted, and the sooner the better – depending on who you ask.

Preparing for the inevitable

The science is unequivocal that the world’s temperature must not rise 1.5 degrees Celsius above pre-industrial levels to avoid the worst effects of climate change. It’s currently 1.1 degrees Celsius warmer, and creeping towards more than 2 degrees Celsius of warming by the end of the century.

Matthias Honegger, a senior consultant at environmental advisory firm Perspectives Climate Group, thinks limiting global warming to 1.5 degrees Celsius by reducing carbon emissions alone is “wishful thinking” at this point. Emissions hit a record high last year, even as the world agreed to hasten climate action.

Honegger, a solar geoengineering researcher, feels that the technology is not maturing fast enough.

“Almost all studies today on solar geoengineering are still at the exploratory stage,” he said. “We lack the institutional and technical ability to monitor and make informed decisions on possible responses.”

We lack the institutional and technical ability to monitor and take informed decisions on possible responses.

Matthias Honegger, senior consultant, Perspectives Climate Group

Honegger added that funding for the technology remains insufficient. He pointed to an article showing that US$8 million was pumped into solar geoengineering research in 2018. A separate study found that total climate research funding for that year was US$2 billion – making the amount allocated to solar geoengineering less than 0.5 per cent.

The latest IPCC paper, which included seven out of over 3,500 pages on what it terms “solar radiation modification”, or SRM, said hundreds of modelling studies have been conducted between 2014 and now. However, they are mostly at the stage of studying the effects of a dimmed sun, not the injection of particles into Earth’s atmosphere.

“Large uncertainties still exist for climate processes associated with SRM options,” the report said. While a general cooling trend has been observed from simulations, the paper added that the impact on crops, human health and ecosystems remains poorly understood. No physical experiments have ever been done.

The report stated that with a better understanding of the technology, solar geoengineering could be one option taken alongside rapid decarbonisation, especially if there is an imminent risk of global temperatures overshooting 1.5 degrees Celsius.

Honegger believes future research should also cover the nexus between Earth science and geopolitics. Current studies show that different regions will cool or heat differently based on how solar geoengineering is conducted, requiring a precise and coordinated global response to prevent collateral damage.

The cost of a global rollout of solar geoengineering systems has already been estimated in a 2018 report – at US$1 to 10 billion a year, to scatter up to five million tonnes of sulphur.

Studies suggest the particles can be delivered by balloons, giant land-based guns or even fighter jets.

Other forms of solar geoengineering, such as by brightening clouds with salt particles to reflect more sunlight, and covering large areas of the sea with a reflective substance, have also been explored but in less detail.

The Carnegie Climate Governance Initiative, a US-based lobby group for the governance of climate-altering technologies, wrote in a policy brief after the latest IPCC report landed that governments should improve their understanding of solar geoengineering to figure out when it becomes better to manipulate Earth’s atmosphere, than to let global temperatures rise further.

“Policymakers may wish to consider how more formal, dedicated international governance around such research may be important and how it could be implemented in practice,” the initiative wrote. It also called for more risk-benefit analyses and public engagements.

While a 2018 IPCC review said the public sentiment towards solar engineering ranged from oblivious to sceptical, the latest report found that poorer countries, who suffer more from climate change, seem to be more receptive to the technology.

Way too risky

“I have been working on technological approaches to climate for my whole career, and one of the things that is increasingly clear is that technology is insufficient,” said Professor Jennie Stephens, director of the school of public policy and urban affairs at Northeastern University in Boston.

“Solar geoengineering is the quintessential technological fix that doesn’t get to the root of the problem and could exacerbate all kinds of other problems,” she said.

Solar geoengineering is the quintessential technological fix that doesn’t get to the root of the problem and could exacerbate all kinds of other problems.

Professor Jennie Stephens, director, school of public policy and urban affairs, Northeastern University

Studies have argued that differing preferences for the extent of cooling could cause countries to purposely deploy chemicals that warm the Earth, or destroy each others’ equipment – potentially leading to armed conflict.

A sudden termination of solar geoengineering measures when the global carbon dioxide concentration is still high could also cause a sharp rise in global temperature, potentially decimating natural and human systems.

Stephens isn’t confident that the global community can overcome these issues.

“We have developed a vaccine for Covid-19. Have we been effective at globally administering the vaccine?” Stephens said. Many developing countries have criticised richer nations for hoarding vaccines. Only 8 per cent of the African population is fully vaccinated, compared to over 55 per cent globally.

Stephens was one of the first signatories to an open letter by 16 scientists, calling for a ban on public funding, experiments and deployment for solar geoengineering technologies in January.

The letter has since been signed by over 300 experts, and a related petition has garnered close to 650 supporters.

A spokesperson behind the initiative, titled the “Solar Engineering Non-Use Agreement”, said the initiators stand by their text and movement after the release of the latest IPCC climate report.

Another open letter against solar engineering was filed by the Saami Council, a non-governmental organisation representing indigenous peoples in Finland, Norway, Russia and Sweden.

The council petitioned for a Harvard-led project to be scrapped last June, saying it contradicted its position on respecting nature.

The project, titled SCoPEx and funded by US billionaire Bill Gates, would have tested releasing chalk dust into the atmosphere via balloons. A planned test flight without the particulate cargo in Sweden was called off last March after a protest by the Saami Council.

“The IPCC report does not affect the Saami Council’s position on solar geoengineering because it is exactly what the IPCC report says – we do not know if this technology could work and it has great risks and uncertainties,” said Åsa Larsson Blind, vice president of the Saami Council.

Larsson Blind said Harvard University has not responded to the open letter. SCoPEx management had said it was reviewing operations and collecting more public feedback last year. The project’s principal investigator, Professor Frank Keutsch, did not respond to emailed requests for comment from Eco-Business.

“I’m confident that research, innovation and new technologies will be needed to find good solutions for the future, but it has to be pointed towards what actually addresses the root causes of climate change – the reduction of emissions,” said Larsson Blind, adding that viewing solar geoengineering as a “Plan B” could cause big emitters to slack on decarbonisation.

Honegger said that not continuing research into solar geoengineering itself could pose a danger, as a lack of knowledge is no guarantee that states wouldn’t unilaterally and bluntly employ the technology, when cornered by climate change.

Stephens disagrees.

“The more you invest in any technology, the more people advocate for that technology, and the more people work for it, the more people think it’s a possibility – it just builds,” she said.

Instead, the world needs “transformative” climate action, such as ditching fossil fuels and addressing the economic and healthcare inequities caused by global warming, she added.

The ethics and governance of solar geoengineering, as well as its associated risks, are expected to be covered in more detail in an upcoming IPCC report on the solutions to climate change.

Clarification: Eco-Business initially reported that SCoPEx did not respond to Saami Council’s open letter, which called for the solar geoengineering project to be suspended. In fact, the open letter was addressed to Harvard University, which hosts the SCoPEx project.

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