This deliverable outlines 5 Case Studies of potential field tests of Solar Radiation Modification (SRM) and related activities, including their technical and non-technical dimensions and implications. These Case Studies are not proposals for actual experiments but are intended to raise key questions and examine the scientific, technical, ethical, social, and regulatory considerations relevant to SRM research governance.
A SRM field experiment refers to a scientific study conducted outside of a laboratory setting, where researchers introduce controlled interventions into a natural environment to observe and analyse the resulting effects and improve understanding related to SRM. While much of the current understanding of SRM comes from modelling studies and laboratory experiments, there is growing interest in field experiments that could provide empirical data to refine model accuracy and improve scientific understanding. The number of SRM field experiments has increased, with five experiments occurring in 2024.
Field experiments directly interact with environmental systems, providing empirical data on atmospheric responses, climate model performance, and potential environmental impacts. However, SRM field experiments require enhanced care and attention to governance frameworks, research ethics, and societal concerns.
This deliverable identifies five Case Studies spanning the leading SRM proposals, different jurisdictions and corresponding legal regimes, and the boundary between SRM and activities that share characteristics with SRM. The foremost SRM techniques of Stratospheric Aerosol Injection, Marine Cloud Brightening, and Cirrus Cloud Thinning are considered, alongside the more localised technique of Sea Ice Thickening. For each of these case studies, a scoping note outlines potential activities as well as the scientific, legal, ethical, participatory, governance and other dimensions they raise. These will help structure later deliberations and analyses and ensure their practical relevance and breadth of scope.
The five Case Studies are:
- Case Study 1: A smaller-scale SAI experiment (10–100 kg H2SO4) in the Seychelles, designed to improve understanding of aerosol plume physics and refine climate models, while examining the challenges of transparent stakeholder engagement.
- Case Study 2: A later-phase SIT experiment in Nunavut, Canada, assessing the feasibility of artificially thickening Arctic Sea ice as a climate mitigation strategy, while considering the role of indigenous communities and traditional knowledge in governance frameworks
- Case Study 3: A smaller-scale CCT experiment in Arctic Norway, exploring the use of ice-nucleating particles to enhance the escape of longwave radiation and reduce the effects of Arctic Amplification, while addressing the challenges of conducting research in the Arctic.
- Case Study 4: A larger-scale MCB experiment in the southeast Atlantic Ocean (offshore of Angola), examining MCB’s potential as a climate intervention technique, while highlighting the governance complexities of transboundary impacts.
- Case Study 5: A larger-scale SAI experiment (1,000 tonnes SO2) in Arctic Finland, investigating stratospheric aerosol dispersion and its implications for radiative forcing and climate model validation, while emphasising the need for international engagement and potential multilateral governance.
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