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December 2024

Solar radiation modification

For decades, technologies have been proposed that would reduce or counteract global warming by reflecting sunlight away from the Earth. These proposals, known as “solar radiation modification” technologies, include stratospheric aerosol injection, cloud brightening, and others.

Climate modelling suggests that some of these technologies might have the potential to prevent further global warming and reduce some of its effects, such as extreme weather events and rising sea levels.

However, none of the technologies is mature and deploying them could have many effects, both intended and unintended. They could have negative impacts on ecosystems, change rainfall patterns, and hamper food production. Moreover, they would not address the direct impacts of greenhouse gases, such as ocean acidification or changes in vegetation patterns. Even if some of these proposals could address the symptoms of climate change, they do not address the cause, and presenting them as solutions could damage the efforts that are already underway to reduce greenhouse gas emissions and adapt to climate change.

The benefits and risks of these proposals are also highly uncertain. Deploying them could have effects on the climate in different parts of the world which would be difficult to predict and difficult to manage in practice.

Furthermore, any large-scale intervention in our common planetary environment would have systemic consequences. Some solar radiation modification applications would need to run for generations-long timescales and have impacts across the entire planet. A strong global governance framework would be needed for this, with adequate representation for all affected parties, and with compensation mechanisms for those potentially harmed. No such framework exists, and it is not clear how one could be created.

Therefore, based on the available scientific evidence, much of which is uncertain and contested, the Group of Chief Scientific Advisors and the European Group on Ethics in Science and New Technologies recommend the following:

  • Continue to focus on reducing greenhouse gas emissions and adapting to climate change as the highest priorities.
  • Announce a Europe-wide moratorium on using solar radiation modification technologies.
  • Negotiate a global governance system for future decisions about deploying solar radiation modification technologies, ensuring it is aligned with fundamental rights and values. Given the current state of knowledge, the EU’s position in global negotiations should be to not deploy the technologies.
  • Hold broad and inclusive public deliberations about fighting climate change, allowing citizens to learn about and debate a range of approaches.
  • Ensure that research into solar radiation technologies is rigorous, ethical and explicit about uncertainties – and includes critical reflection on the full range of direct and indirect effects, governance and justice issues.
  • Reassess the evidence on risks and potential opportunities every five to ten years.

Scientific advice

Requested by

Delivery date

9 December 2024

Supports EU mission

Adaptation to climate change

Supports UN sustainable development goals

Climate action

The Group of Chief Scientific Advisors responds to the request for advice from the European Commission.

Their policy recommendations are based on the best available scientific evidence.

SRM opinion cover
Bibliographic information
DOI
10.2777/391614
ISBN
9789268195680
Licence
Creative Commons Attribution
Cite as
European Commission: Directorate-General for Research and Innovation & Group of Chief Scientific Advisors. (2024). Solar radiation modification. Publications Office of the European Union.
The Scientific Opinion is written jointly by the Group of Chief Scientific Advisors. Former Advisors (‘alumni’) may also contribute.
Naomi Ellemers

Naomi Ellemers

Advisor
Portrait of Nicole Grobert

Nicole Grobert

Advisor
Portrait of Maarja Kruusmaa

Maarja Kruusmaa

Advisor
Portrait of Eric Lambin

Eric Lambin

Advisor
Portrait of Alberto Melloni

Alberto Melloni

Advisor
Portrait of Nebojša Nakićenović

Nebojša Nakićenović

Advisor
Portrait of Eva Zažímalová

Eva Zažímalová

Advisor

Events

11 March 2025
Solar radiation modification: What are the technologies, and what are the risks?
Online event
Solar Radiation Modification (SRM) covers a range of technologies that have the potential to cool the Earth’s climate. SRM is therefore the subject of intense and controversial debate around whether it might provide a means to tackle global warming and the devastating impacts of climate change.
3 February 2025
Solar Radiation Modification: What’s at stake for society?
Online event
Solar Radiation Modification (SRM) covers a range of technologies that have the potential to cool the Earth’s climate. SRM is therefore the subject of intense and controversial debate around whether it might provide a means to tackle global warming and the devastating impacts of climate change.
23 January 2025
Solar radiation modification: What should Europe’s strategy be?
Online event
Solar Radiation Modification (SRM) covers a range of technologies that have the potential to cool the Earth’s climate. SRM is therefore the subject of intense and controversial debate around whether it might provide a means to tackle global warming and the devastating impacts of climate change.
Uncle SAM

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