Plans to cool the Earth by blocking sunlight are gaining momentum but critical voices risk being excluded

Solar geoengineering research is advancing fast, after a recent flurry of funding announcements. Yet these technologies are still speculative and have many critics, and we worry their concerns won’t be heard. If geoengineering is essentially allowed to self-regulate, with no effective global governance, future research could easily take us down a dangerous path.

Solar geoengineering refers to proposals to reduce global warming by reflecting a portion of sunlight back into space before it reaches the Earth’s surface. In its best-known form, this means using high-flying aircraft to inject tiny reflective particles into the upper atmosphere.

This so-called “stratospheric aerosol injection” hasn’t actually happened yet, beyond a few very small experiments with balloons. Yet for a long time, such ideas remained fringe and too controversial to even consider – and for some academics they still are.

The academic discussion was highly polarised from the start. Opponents, mainly governance scholars and social scientists, stood firmly entrenched against assumed proponents, mainly natural scientists and engineers. Both sides had their champions, arguments, assumptions, key publications and meetings, generally working on the topic without proper engagement with the other side.

This polarisation is still visible in publishing today. Take, for example, articles on The Conversation. Critics focus on potential negatives such as altered rainfall patterns, the infringement of human rights, or even a catastrophic “termination shock”. Advocates highlight potential benefits such as reducing extreme heat and preserving ice caps, while others suggest we may soon be forced to try it.

The authors of these articles are all academic experts. Yet they come from different disciplines and use different arguments.

A public and private funding boom

Though the two camps have not resolved their arguments, geoengineering research funding is suddenly booming. There are major philanthropic pledges of US$50 million (£38 million) and US$30 million from the Simons and Quadrature Climate foundations, which are vying for the title of biggest donor with the £10.5 million and £56.8 million of the UK government’s UKRI and Advanced Research and Innovation Agency programs.

Other key organisations speaking about the need for more research include the European Commission, the US government and the World Climate Research Programme. This comes on top of the shock of controversial private enterprises pushing for solar geoengineering, most notoriously the US-based start-up Make Sunsets.

Support is certainly not unanimous. Many prominent scholars have signed up to a call for a moratorium, for instance. And at a recent UN Environment Assembly session in Kenya many climate-vulnerable nations mobilised against calls for further research into what they see as a highly risky technology that would enable big emitters to carry on emitting.

However, many powerful interests are seemingly in favour of more research, while the 1.5°C global warming target is moving ever further out of sight. In the near future, we can therefore expect further research, perhaps including including small-scale outdoor experiments.

As PhD students working on geoengineering, situated somewhere between both camps, we have found this polarisation deeply unproductive and difficult to deal with. Our own research sometimes feels like wandering through a minefield of opinions and perspectives. Yet we can also see the valuable concerns and hopes of both sides.

That’s why we believe that upcoming research projects must factor in the concerns of opponents, and not represent only supporters of geoengineering or those who have not been explicitly against it. Excluding critical voices would directly impact the scientific process, for one thing.

But this exclusion is especially worrying as there are currently no governance structures for solar geoengineering. If efforts to develop such governance only involve supportive researchers, they could lack the critical capacity to prevent risks or undesired effects. Disasters in the financial sector and the chemical industry warn us of the perils of self-regulation without critical voices.

Learn from the critics

There are other critiques that ought to be factored into any major research project. They include concerns that simply researching the technology will create a slippery slope towards it being deployed, or worries that geoengineering ignores the social and political dynamics behind climate change and addresses only its outcomes. There are also major governance concerns over issues such as the role of the military (could geoengineering be deployed for security reasons in contested regions like the Arctic?), or the concentration of research at influential institutions in the US and Europe.

Over time, geoengineering researchers have become more aware of such arguments and some are explicitly trying to include them in their work. The American Geophysical Union has recently published an ethical framework for geoengineering, which should provide valuable guidance for any research project. But without active dialogue with critical scholars, their arguments will likely only echo faintly in the pro-research space.

In practice, more engagement between the two camps would come with many difficulties. For advocates, it can be tempting to avoid such debates and exclude those who disagree with the very foundations on which their research is built. On the flip side, some scholars who have already explicitly argued against the continuation of solar geoengineering research would nevertheless have to participate in it.

The practical implications will therefore need to be carefully worked out. However, a more productive dialogue might still shape a future that can be acceptable to all sides.

Albert Van Wijngaarden receives PhD funding from Gates Cambridge. He is involved in UArctic's Frozen Arctic Conservation project, and was an advisory board member of Ocean Vision's Sea Ice Roadmap.

Adrian Hindes is also an analyst for Civilization Research Institute which does work pertaining to global catastrophic risks, including those related to emerging technologies such as solar geoengineering.

Chloe Colomer receives PhD funding from the UK Research Institute (UKRI) Engineering and Physical Sciences Research Council (EPSRC) with the grants EP/R513143/1 and EP/T517793/1.