This paper assesses the concepts of solar geoengineering and ecocide law, arguing that while wide-scale instantiation of both solar geoengineering deployment and the implementation of a crime of ecocide remain, as yet, theoretical, there exist many obvious parallels between the two phenomena. Firstly, by briefly reviewing definitional and historical parallels between the concepts, including their focus on scale and intent, it will be argued that ecocide law could naturally build upon existing international law and serve as a useful analytical tool for reviewing the legality or otherwise of solar geoengineering deployment. Secondly, it is argued that ecocide law, in conjunction with polycentric governance, could ensure more adequate environmental protection for the global commons in the face of solar geoengineering, as well as providing a legitimate and robust legal framework for discussing any such developments, reinforced by internationally enforceable rights on planet earth and in outer space.