Climate engineering

In June 2020, EPFL International Risk Governance Center (IRGC) released “International Governance Issues on Climate Engineering”, a study conducted for the Swiss Federal Office for the Environment (FOEN), International Affairs Division. The report’s four chapters, authored by experts in the field, draw together information and recommendations relevant to international policymaking in this area of growing importance to preventing climate change. “Policy decisions must strive to be based on evidence and a shared, robust understanding of the potential opportunities and risks, across disciplinary and applied perspectives.”

Some climate engineering techniques are being developed to remove CO2 from the atmosphere (carbon dioxide removal, CDR). Some other technologies (grouped under the term of solar radiation modification, SRM) would artificially cool the planet and could reduce some symptoms and consequences of climate change.

Human-caused climate change poses severe risks to people and ecosystems, especially the most vulnerable among them. The Intergovernmental Panel on Climate Change (IPCC) indicates in its latest reports that, in order to comply with the global warming goals provided for by the Paris Agreement (keep warming well under 2°C above pre-industrial levels), there is a need to reach global net-zero CO2 emissions in the second half of this century, and carbon removal will be needed. Climate engineering could be part of international climate policy, but clearly distinguish between CDR and SRM for their very different possible roles in combating climate change. Meaningful steps may need to be taken soon to lay a foundation for a decision process regarding research, policy, regulation and possible use.

  • Chapter one of the report (written by Paul Rouse, C2G) provides an overview of the two classes of emerging climate engineering technologies—CDR and SRM—regarding their potential to contribute to climate change reduction, and the various specific techniques’ readiness level, cost and risks.
  • Chapter two (written by Anna-Maria Hubert, University of Calgary) surveys legal norms and existing international agreements that govern the use of the techniques.
  • Chapter three (Matthias Honegger, IASS) analyses trade-offs between risks and approaches to resolve them.
  • Chapter four (Jesse Reynolds, UCLA) evaluates possible policy options and approaches for international governance of climate engineering.

Four cross-cutting themes emerge from this study:

  • Noting the pervasive scientific uncertainty that characterizes both CDR and SRM, adaptive approaches are needed to reducing uncertainty and deploying the most appropriate technologies and governance mechanisms. One needs to be very prudent and avoid lock-ins.
  • Separating CDR and SRM in policy discussion and in communication with the public might help reduce ambiguity
  • Existing international arrangements lean toward –or even in some cases create an obligation to– engage in further research and cooperation.
  • Both top-down and bottom-up approaches to the national and international regulation of CDR and SRM are needed.

The recommendations for governance are

  • To distinguish between CDR and SRM as well as among the diverse CDR techniques in their additional dedicated governance
  • To accelerate authoritative, comprehensive and international scientific assessment
  • To encourage the research, development, and responsible use of some CDR techniques
  • To help build capacity for evaluating CDR and SRM in some of those countries that lack the resources to do so
  • To facilitate the elaboration and implementation of non-state governance; and
  • To explore potential further governance of SRM while remaining agnostic concerning its ultimate use.


  • International Governance Issues on Climate Engineering, 2020, Report

    Correction: This document was updated on July 6 2020 to correct an error on page 44. Previously, the final sentence referred to simulations indicating that a 0.05% increase in ocean albedo may create 2.7°C of surface cooling. The correct figure is 5%, not 0.05%.

The report was released on 18 June, GENeva Environment Network:

Link to Swiss Federal Office for the Environment: