Climate change may be characterised as the greatest global long-term threat to the health of the planet. Until relatively recently, its impact on and potential implications for the oceans has generated little concern, at least in comparison with the atmosphere and biosphere. This is changing however, as the impacts of a warmer ocean on ecosystems and biodiversity, sea level rise and ocean acidification are better understood. Its subordinate status nevertheless is perpetuated by the climate change regime, which pays relatively little attention to both the impacts of climate change on the oceans and the capacity of the ocean to mitigate climate change through its function as a carbon dioxide sink. Moreover, the characterisation of the ocean as a sink to be exploited to mitigate climate change, demonstrates the complex legal and moral relationship between the oceans and atmosphere and between organisations with responsibility for the oceans and atmosphere. This Chapter will explore that complex legal and moral relationship, and will examine how linkages and connections between regimes with responsibility for the oceans and for the atmosphere can—indeed must—be developed in order to develop ecologically and legally coherent responses to climate change. This Chapter will conclude with a proposal, advocating the adoption of a ‘Declaration on Climate Change and the Oceans,’ designed to provide a framework for cooperation and a catalyst for action, integrating climate and oceans policy.