This article describes the challenges of using the constrained tools of international law to negotiate a sustainable framework to address climate change. It sets out to show how the particularities of the problem have led to creative and innovative solutions expanding the borders of international law. To this end, the article discusses carbon market mechanisms, the compliance regime of the Kyoto Protocol, and the emerging framework to create incentives to reduce land-based emissions in developing countries. These examples illustrate that the recognition of the role of sub-national and private entities in mitigating climate change has had significant impact on the rules of the climate regime. But the article also asserts that the un process, while recognizing the role of private actors, is still inadequately equipped to involve non-state actors in a meaningful way. The climate regime therefore challenges the traditional thinking about interstate relationships. No longer solely a matter for international environmental law, contemporary environmental governance has become a global affair, which makes the lens of transnational law a useful tool to think about these issues in practice in a more intellectually fruitful and relevant way. This article thereby provides a snapshot of the type of issues and discussion that readers of this journal can look forward to in the years to come.