未来能源研究所-太阳能地球工程威胁下的国际气候协定（英）-2023.9-36页_554kb

Summary of “International Climate Agreements under the Threat of Solar Geoengineering”

This paper analyzes how the availability of solar geoengineering (SGE) technologies—intended to mitigate climate change by reflecting solar radiation—affects international environmental agreements (IEAs) on emissions reductions. Using a game-theoretic model, the authors demonstrate that SGE introduces two strategic incentives that challenge IEA stability:

• Free-rider incentive: Countries benefit from leaving agreements and reducing their abatement efforts.
• Anti-driver incentive: Countries benefit from staying in agreements to increase abatement and counteract SGE deployment by a "free-driver" nation.

Key findings include:

• SGE can increase or decrease non-cooperative abatement levels, depending on whether the free-driver's deployment harms other countries.
• Under homogeneous preferences, SGE does not alter the maximum stable IEA size of three members.
• With heterogeneous preferences, if the anti-driver incentive is strong enough (e.g., when the free-driver causes significant harm), SGE can expand the breadth (participation) and depth (abatement level) of stable IEAs beyond what is achievable without SGE.

The analysis highlights that while SGE poses governance challenges (e.g., the free-driver problem), it may paradoxically motivate more international cooperation when damages from unchecked deployment are severe.