Switzerland calls on UN to explore possibility of solar geoengineering

Proposal focuses on technique that fills atmosphere with particles, reflecting part of sun’s heat and light back into space

Switzerland has initiated a global debate on whether the “risks, benefits and uncertainties” of dimming the sun should be studied by a United Nations expert group.

It is proposing that the world body should gather information about ongoing research into solar geoengineering, and set up an advisory panel that could suggest future options for the untested and controversial approach to reduce global heating, which would have implications for food supply, biodiversity, global inequality and security.

The Swiss proposal, submitted to the United Nations environment assembly that begins next week in Nairobi, focuses on solar radiation modification (SRM). This is a technique that aims to mimic the effect of a large volcanic eruption by filling the atmosphere with sulphur dioxide particles that reflect part of the sun’s heat and light back into space.

Supporters of the proposal argue that research is necessary to ensure multilateral oversight of emerging planet-altering technologies, which might otherwise be developed and tested in isolation by powerful governments or billionaire individuals.

Critics, however, argue that such a discussion would threaten the current de-facto ban on geoengineering, and lead down a “slippery slope” towards legitimisation, mainstreaming and eventual deployment.

Felix Wertli, the Swiss ambassador for the environment, said his country’s goal in submitting the proposal was to ensure all governments and relevant stakeholders “are informed about SRM technologies, in particular about possible risks and cross-border effects”. He said the intention was not to promote or enable solar geoengineering but to inform governments, especially those in developing countries, about what is happening.

The executive director of the UNEP, Inger Andersen, stressed the importance of “a global conversation on SRM” in her opening address to delegates at a preliminary gathering in Nairobi. She and her colleagues emphasised the move was a precautionary one rather than an endorsement of the technology.

But no matter how well intentioned the proposal might be, some environmental groups are alarmed at the direction of travel. “There’s a real risk that mandating UNEP to write a report and set up an expert group on SRM could undermine the existing de facto moratorium on geoengineering and inadvertently provide legitimacy for delaying actions to phase out fossil fuels,” said Mary Church of the Center for International Environmental Law (CIEL). “There are some areas that the international community has rightly decided are simply off limits, like eugenics, human cloning and chemical weapons. Solar geoengineering belongs on that list and needs to join it fast, before seemingly harmless conversations on governance lead us down a very slippery slope towards deployment.”

Switzerland last proposed scrutiny of geoengineering at the 2019 UN environment assembly in 2019 but the topic was blocked by the United States and Saudi Arabia. Sources said this was because they wanted to conduct research into these technologies unfettered by international oversight or regulations.

Since then, the debate on sun-dimming research has intensified and widened. In the past, this was an area partly funded by the fossil fuel industry, but in recent years, more actors have become involved, including philanthropists, financiers and hi-tech entrepreneurs, motivated by potential lucrative rewards and growing alarm about climate dangers. More money is flowing into the sector particularly in the United States, where Bill Gates is among supporters of the Harvard solar geoengineering research program, and groups such as the National Academies of Sciences, Engineering, and Medicine, Environmental Defense Fund, the Union of Concerned Scientists, and the Natural Resources Defense Council have expressed support for further studies into sunlight reflection technologies. The sector sometimes evinces a wild-west, make-up-the-rules-as-you-go-along, profiteering spirit, most evident in the US start-up Make Sunsets, which is already selling “cooling credits” and claiming to have conducted outdoor tests in Mexico.

The Mexican government has subsequently banned such experiments on its territory. The European parliament stressed the need for restrictive governance and the application of the precautionary principle in a statement last year on solar geoengineering.

In 2022, about 500 scientists signed an appeal for a solar geoengineering non-use agreement that stipulated no public funding, no deployment, no patents, no experiments, and no support in international forums.

In scientific forums, SRM is a growing focus of concern. The Intergovernmental Panel on Climate Change noted critical knowledge gaps and risks related to SRM in their Sixth Assessment Report. Last January, the Montreal Protocol reported for the first time on the damage that could be done to the ozone layer from the SRM technique known as a stratospheric aerosol injection.

Last year, the UN environment programme was criticised for publishing a paper on solar geoengineering, One Atmosphere, which included contributions from advocates of SRM and recommendations for more research including open air experiments. CIEL said this helped the deployment of the technology.

UNEP’s chief scientist, Dr Andrea Hinwood, said such accusations were unfair because her organisation was not advocating for these technologies and emphasised the priority was to reduce emissions.

“At the same time, we don’t want to be in a position where some months or even years down the track we are caught off-guard and playing catch-up,” she said. “I know people think this is potentially creating a space where these technologies may be supported, but I also think not discussing them is more problematic.”

In Nairobi, the fate of the Swiss proposal hangs in the balance. Senegal, which was initially a co-sponsor, has backed out. Many other nations, including once again the US and Saudi Arabia, have expressed doubts. The African delegates have stressed no-use. But Wertli said he believed the mood was more positive than in 2019. “This time, you can see people are ready to discuss because the debate has progressed,” he said. “There was a general acknowledgment in the opening debate that more research and information is needed. That is new and shows that the resolution responds to a need.”

Cover photo: The moon crosses in front of the sun over the Juscelino Kubitschek memorial during an annular eclipse in Brasilia, Brazil in October 2023. Photograph: Ueslei Marcelino/Reuters