Scientists call for International Non-Use Agreement on Solar Geoengineering

Published on 18 January 2022

A global coalition of over 60 senior climate scientists and governance scholars have launched a global initiative calling for an International Non-Use Agreement on Solar Geoengineering. They argue that deployment of solar geoengineering – speculative technologies that aim to lower global temperatures by artificially intervening in our climate systems – cannot be fairly governed globally and poses an unacceptable risk if implemented as a future climate policy option.

The group, including IDS Director Prof Melissa Leach, is calling on fellow academics, civil society organizations and concerned individuals to sign an open letter to governments, the United Nations and other actors to stop development and potential use of planetary-scale solar geoengineering technologies. The initiative draws on an academic journal article co-authored by 16 scientists leading the initiative.

Dangerous planetary-scale interventions

The call for a non-use agreement particularly warns against the most widely debated speculative solar geoengineering technology – the massive spraying of aerosols in the stratosphere to block a part of incoming sunlight to cool the planet. Such dangerous planetary-scale interventions cannot be governed in a globally inclusive, fair and effective manner and must therefore be banned, argue the group of scientists and governance experts.

Professor Frank Biermann from Utrecht University, a leader of the call for a Non-Use Agreement on Solar Geoengineering, comments:

“Solar geoengineering deployment is ungovernable in a fair, democratic and effective manner. For the last few decades, solar geoengineering has been a research topic for just a small group of scientists based largely at elite universities in the US and the UK. Now other science communities and civil society must step in and raise their voice. Governments must take control. The development of solar geoengineering technologies must be stopped.”

The open letter highlights that betting on solar geoengineering as a potential future solution threatens “commitments to mitigation and can disincentivize governments, businesses, and societies to do their utmost to achieve decarbonization or carbon neutrality as soon as possible. The speculative possibility of future solar geoengineering risks becoming a powerful argument for industry lobbyists, climate denialists, and some governments to delay decarbonisation policies”.

A threat that requires immediate action

In early 2021, this was one of the reasons presented by the indigenous Saami Council and environmental NGOs to stop a balloon test for a Harvard University solar geoengineering research programme. Planned for June 2021 above indigenous territory in Sweden, the test was halted after strong civil society opposition. Such tests should be banned world-wide, the group of 60 experts now argue.

The 60 leading climate scientists and governance experts also fear that without an inter-national ban or restrictions, a few powerful countries with support from major corporations and philanthropists could engage in solar geoengineering unilaterally or in small coalitions, even when the rest of the world opposes such deployment or has not yet had the time to assess it and its potential dangers. This threat, the group argues, therefore requires immediate action by governments and the United Nations for an International Non-Use Agreement on Solar Geoengineering.

The open letter calls upon governments to support five core prohibitions and measures to:

  • Prohibit their national funding agencies from supporting the development of technologies for solar geoengineering, domestically and through international institutions.
  • Ban outdoor experiments of solar geoengineering technologies in areas under their jurisdiction.
  • Refuse patent rights for technologies for solar geoengineering, including supporting technologies such as for the retrofitting of airplanes for aerosol injections.
  • Not deploy technologies for solar geoengineering if developed by third parties.
  • Object to future institutionalization of planetary solar geoengineering as a policy option in relevant international institutions, including within assessments by the Intergovernmental Panel on Climate Change.

Take action

To take action sign the open letter at or the petition at For further information and updates follow @SolarGeoeng on Twitter.


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