This article explores the adequacy of the international rules on environmental impact assessment to contribute to geoengineering governance, with a focus on three fundamental challenges. First, the near-universal trigger for eia is the likelihood of significant environmental impact, which may prove to be insufficiently precautionary in light of current risk preferences surrounding geoengineering. Second, the scope of eia has traditionally focused narrowly on the assessment of direct physical impacts; however, many of the concerns that geoengineering research raises relate to environmental and social risks associated with downstream technological implications. A third and related challenge is the consultation requirements under eia laws, which focus on affected states and affected members of the public. Because many geoengineering activities are anticipated to impact the global commons, there is no clear institutional mechanism for implementing notification and consultation. Additionally, the broader sets of concerns that geoengineering raises are spatially unbounded, again making the identification of consultation partners uncertain. The article concludes with a discussion of the implications of the challenges and limitations of the rules of eia for geoengineering.