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The Case for an International Non-Use Agreement on Solar Geoengineering

Given the slow pace of global climate policy, the call for a planetary techno-fix for rising climate risks is gaining momentum.


Widely discussed is “solar geoengineering”, a set of hypothetical technologies that would lower global temperatures, for instance by spraying of aerosols in the stratosphere. These tiny particles would scatter a small part of incoming sunlight back into space.


A few research groups have begun study programmes on solar geoengineering and some see this even as a potential future policy option.


Yet, solar geoengineering is no solution.


First, few would disagree that the risks of solar geoengineering are possibly huge, but also poorly understood, and they can never be fully known. Solar geoengineering would be an experiment at planetary scale, and its efficacy could be judged only after deployment. The impacts of solar geoengineering will also vary across regions, with huge uncertainties about how the technology will affect weather patterns, agriculture and provision of basic needs such as food and water. The global poor, as is often the case, might be most at risk.


Second, speculative fantasies about the future availability of solar geoengineering technologies threaten today’s commitments to cutting climate-heating emissions.


Once powerful actors begin to believe in solar geoengineering, they might stop doing their utmost to reduce their greenhouse gas emissions. The pipedream of solar geoengineering then turns into a powerful argument for industry lobbyists, climate denialists, and some governments to delay decarbonization policies.


Research on solar geoengineering is not the preparation of a Plan B to prevent climate disaster, as its advocates argue. It will instead simply delay and derail global climate policy.


Third, there is no imaginable way the current multilateral system could govern solar geoengineering deployment in a fair, inclusive and effective manner.


The United Nations, set up in 1945, was never designed to “manage” solar radiation and the global temperature by the massive spraying of aerosols in the stratosphere. Yet without effective global control, the geopolitics of solar geoengineering are frightening. Small coalitions of a few powerful countries could unilaterally begin with solar geoengineering even when most other countries oppose this.


Some advocates of solar geoengineering respond that we don’t need the United Nations. We could work with informal governance arrangements, such as voluntary codes of conduct of scientists.


But technocratic governance based on expert commissions, often heavily dominated by experts from the Global North, cannot resolve complex global conflicts over values and differences in risk acceptance.


In short, we need immediate political action to stop the normalization of solar geoengineering as a climate policy option. Governments must restrict the development of solar geoengineering technologies before it is too late.


Together with a global group of over 60 senior climate scientists and governance scholars, I advocate for an International Non-Use Agreement on Solar Geoengineering specifically targeted against the development and deployment of such technologies at planetary scale.


Governments should agree on a set of core commitments: Governments must prohibit their national funding agencies from supporting the development of technologies for solar geoengineering, and they should agree to ban outdoor experiments of such technologies.


Governments must refuse patent rights for solar geoengineering technologies and declare not to deploy such technologies if developed by third parties. Governments must agree to object to future institutionalization of planetary solar geoengineering as a policy option in international institutions, including the Intergovernmental Panel on Climate Change.


The International Non-Use Agreement on Solar Geoengineering would not prohibit atmospheric or climate research as such and would not place broad limitations on academic freedom.


The agreement would focus solely on specific measures targeted to restrict the development of solar geoengineering technologies under the jurisdiction of the parties to the agreement.


An International Non-Use Agreement on Solar Geoengineering would be timely, feasible, and effective. It would inhibit further normalization and development of a risky and poorly understood set of technologies that seek to intentionally “manage” incoming sunlight at planetary scale. And it would do so without restricting legitimate climate research.


Decarbonization of our economies is feasible and now urgent. Solar geoengineering is not necessary – nor is it desirable, ethical, or politically governable in the current context.

A strong political message to block these technologies is required. An International Non-Use Agreement on Solar Geoengineering is needed now.


(This blog was also published on 17 January 2022 with Thomson Reuters)