The Paris Agreement to the United Nations Framework Convention on Climate Change (UNFCCC) signifies a shift in how the principle of common but differentiated responsibilities (CBDR) manifests in the international climate change regime. Unlike the UNFCCC and its Kyoto Protocol, the Paris Agreement does not enshrine differentiated substantive mitigation obligations for developed and developing countries. However, an increasingly proceduralized variant of the CBDR principle, which facilitates regard for the interests of developing countries with respect to treaty implementation yet does not guarantee favourable substantive outcomes for these states, is evident in the emerging regime. The experience of the International Maritime Organization’s climate change regime provides a cautionary tale with respect to procedurally oriented differentiation that is not reinforced by effective processes to ensure that developed states honour their finance and technology transfer commitments. Accordingly, this article posits that strong accountability mechanisms are required to transform opportunities for procedural differentiation in the Paris Agreement into a robust framework for procedural regard for the interests of developing states.

The Kyoto Protocol is remarkable among global multilateral environmental agreements for its efforts to depoliticize compliance. However, attempts to create autonomous, arm’s length and rule-based compliance processes with extensive reliance on putatively neutral experts were only partially realized in practice in the first commitment period from 2008 to 2012. In particular, the procedurally constrained facilitative powers vested in the Facilitative Branch were circumvented, and expert review teams (ERTs) assumed pivotal roles in compliance facilitation. The ad hoc diplomatic and facilitative practices engaged in by these small teams of technical experts raise questions about the reliability and consistency of the compliance process. For the future operation of the Kyoto compliance system, it is suggested that ERTs should be confined to more technical and procedural roles, in line with their expertise. There would then be greater scope for the Facilitative Branch to assume a more comprehensive facilitative role, safeguarded by due process guarantees, in accordance with its mandate. However, if – as appears likely – the future compliance trajectories under the United Nations Framework Convention on Climate Change will include a significant role for ERTs without oversight by the Compliance Committee, it is important to develop appropriate procedural safeguards that reflect and shape the various technical and political roles these teams currently play.

As international negotiations struggle to deliver timely, binding commitments to reduce greenhouse gas emissions to safe levels, the environmental legal community has begun to contemplate the scope for climate governance ‘beyond’ the international climate change regime. Many see merit in a more decentralized, disaggregated approach, operating across multiple governance levels. This article examines the development of climate change law in an era of multi-level governance. It analyzes several case studies of current manifestations of multi-level governance in climate change law, including the fragmented global emissions trading system, developing arrangements governing forests and land-based sinks, the growth of climate litigation establishing transnational liability principles, efforts to ensure adaptation to unavoidable climate change, and the emergence in federal systems of a decentralized approach to climate change regulation. The article concludes by considering whether the emerging multi-level system of climate governance is adequate to meet broader international goals of climate change mitigation and adaptation.