Global climate change and governance will widely but unevenly impact people’s lives around the world. There is thus an urgent need to ensure that the people who will be affected by climate change itself, as well as by mitigation and adaptation measures, are appropriately represented in decision making processes. In short, there is an urgent need to democratise global climate governance. But the absence of traditional liberal democratic mechanisms in the international system poses an obvious challenge to democratising global governance. A plausible alternative to the cosmopolitan ambition of importing the domestic democratic architecture to the international system is to enhance the deliberative capacity of existing governance arrangements. Deliberative governance arrangements offer perhaps the most promising opportunity for responding to the social challenges of global climate change and governance. The effective functioning of these arrangements depends crucially on vibrant public space being integrated into the deliberative system. Ideally, this space should be represented by a wide range of discourses and provide the conditions for a free exchange of ideas. Our purpose here is to assess how well the public space is fulfilling this function within the global deliberative system for governing climate change. In the first part of the paper we introduce the concept of a deliberative system and clarify the role of the public space within this system. In the second part of the paper we draw on interviews with civil society representatives, forum observations, and a comprehensive discourse analysis to assess the strengths and weaknesses of existing deliberation within the global public space and reflect on the opportunities for enhancing its capacity to respond to the social challenges of global climate change and governance.