This chapter will explore the concept of transboundary environmental governance in the context of a new and emerging threat to the marine environment: geoHQJLQHHULQJ'H¿QHGDVµWKHGHOLEHUDWHODUJHVFDOHPDQLSXODWLRQRIWKHSODQHWDU\ environment to counteract anthropogenic climate change’,1 over half of geoengineering strategies proposed to date are designed to be deployed in, or RWKHUZLVHVLJQL¿FDQWO\LPSDFWXSRQWKHPDULQHHQYLURQPHQW'HVSLWHWKHIDFWWKDW JHRHQJLQHHULQJWHFKQRORJLHVDUHDV\HWODUJHO\FRQ¿QHGWRWKHUHVHDUFKVWDJHRI development, questions have already been raised within national, regional and international fora as to whether and how geo-engineering should be regulated.2 As with any new activity that poses a risk to the marine environment, the principal governance dilemma is whether that activity can be regulated or controlled through existing regulatory instruments or whether a new regime must be developed. This chapter argues that a recent strategic development in international environmental governance supports the regulation of geo-engineering technologies through existing instruments and institutions and renders the creation of a new regime VXSHUÀXRXV7KLVGHYHORSPHQWFRPSULVHV WKHGHOLEHUDWHFUHDWLRQRI LQVWLWXWLRQDO connections and relationships between treaty regimes, which permit the formation of cooperative arrangements between international environmental institutions designed to more effectively address environmental threats.3 In short, the central thesis of this chapter is that in responding to geo-engineering as a new threat to the

1 The Royal Society (UK), Geoengineering the climate: Science, governance and uncertainty (RS Policy Document 10/09, 2009) at 1 (hereinafter, Royal Society, Geoengineering the climate).