This article offers a socio-legal analysis of the role played by the principle of common but differentiated responsibilities (CBDR) in the development, diffusion, and implementation of jurisdictional REDD+ activities throughout the developing world. It employs a qualitative research method known as process tracing to uncover whether and, if so, to what extent and how actors have used CBDR to support the emergence and effectiveness of the transnational legal process for REDD+. The article argues that the transnational legal process for REDD+ reflects a conception of CBDR in which developing country governments may take on voluntary commitments to reduce their carbon emissions, with the multilateral, bilateral, and private sources of financial support and technical assistance provided by developed countries, international organizations, non-governmental organizations, and corporations. This creative conception and application of CBDR has fostered the construction and diffusion of legal norms for REDD+ because it has influenced the interests, ideas, and identities of public and private actors in the North and South. However, the early challenges associated with the implementation of REDD+ reveal a worrying gap between the financial pledges made by developed countries and the costs associated with the full implementation of REDD+, as well as contradictions in the very way in which the responsibilities of various countries have been defined in the context of REDD+. The analysis has important implications for the transnational governance of REDD+, as well as for scholarship on the role of differentiation in the pursuit of effective and equitable climate change solutions.

The Paris Agreement has struck a careful balance between the need for ambitious and effective climate action and for fair effort sharing among parties based on differentiation. This article provides an overview of the negotiation history of differentiation and analyzes the ‘dynamic differentiation’ as built into the architecture of the Agreement. While being set against the normative background of the United Nations Framework Convention on Climate Change (UNFCCC), the Paris Agreement adopts a more diversified way of differential treatment among parties, approaching it in three complementary ways: firstly, on a principled basis, reflecting common but differentiated responsibilities and respective capabilities (CBDR-RC), in the light of different national circumstances; secondly, in the content of its articles, in particular on mitigation, finance and transparency; and thirdly, on the basis of the principles of progression and highest possible ambition, which represent new and dynamic aspects of differentiation. The authors argue that ‘highest possible ambition’ is reflective of a duty of care that states now need to exercise. It implies a due diligence standard, which requires each government to act in proportion to the risk at stake and to take all appropriate and adequate climate measures according to its responsibility and its best capabilities. By expecting parties to apply this standard at each successive preparation of nationally determined contributions (NDCs), and to progress beyond previous ones, the Paris Agreement has set up reiterative processes, an ‘international normative pull’ and a collective learning environment. This, in turn, creates a reflexive approach to parties’ determination of effort, promoting the evolution of voluntary cooperative behaviour.

Differential treatment in international environmental law is the broader manifestation of the principle of common but differentiated responsibilities (CBDRs). It reflects equity concerns that have underlain most environmental debates on a North-South basis for several decades. Over the past two decades, various forms of differentiation have been introduced in environmental law instruments to the point where it has become an essential element of any international environmental agreement. At the same time, differential treatment has been the object of sustained criticism, arguing that it should be temporary, that it fails to target beneficiaries appropriately, and undermines environmental outcomes. This article takes the opposite view and argues that differentiation remains crucial in a world where widespread inequalities remain. Beneficiaries need to be identified on the basis of environmental and social indicators and differentiation should constitute the basis on which environmental measures are adopted. Worsening environmental conditions and an evolving global context call for adding new elements to the existing framework for differentiation. This requires thinking beyond the current structure centred around nation states and conceptualizing differentiation around common heritage equity. It also requires expanding differentiation beyond the field of environmental law, to include all areas of sustainable development law. Further, differential treatment needs to be implemented in a way that benefits the most disadvantaged in every country. These measures are necessary to foster a vibrant international environmental law which addresses the equity needs of all states in years to come.

The landmark 2015 decision by the Hague District Court in Urgenda v. The Netherlands represents the first time a national court has expressly used the international environmental law (IEL) principle of common but differentiated responsibilities and capabilities (CBDRs) of the climate regime as a complementary tool to interpret the scope of a state’s climate obligations under domestic law. This article highlights that despite the marked engagement of national courts with IEL in recent decades (including engaging with principles such as sustainable development, polluter pays, intergenerational equity, and precaution), until this decision CBDRs had remained outside the purview of environmental law jurisprudence at the national level. The article examines how the Hague Court used CBDRs to help address two common barriers to climate liability: causation and the ‘political question’ doctrine. The article argues that the Court was able to find normative content in a core element of the climate-related CBDRs: the ‘leadership’ role of developed countries in climate action. This core element has remained remarkably consensual throughout the contested history of CBDRs in the climate regime – a history that has gained a new chapter with the signature of the Paris Agreement in December 2015. The article concludes that Urgenda v. The Netherlands may serve as a starting point for a more productive and extensive use of CBDRs in climate litigation, provided litigants make more explicit use of the persuasive authority of the principle.

Transnational carbon major companies are responsible for over 30% of global industrial greenhouse gas emissions and exert tremendous influence over future global climate trajectories. Yet, they are not governed through top-down, stringent emissions limits, but are instead regulated largely by disclosure-only domestic requirements and market-based or voluntary corporate social responsibility mechanisms. Through an examination of the requirements of domestic laws such as the United Kingdom (UK) Climate Change Act 2008 and the UK Energy Act 2013, as well as the environmental and sustainability reports produced under the UK Companies Act 2006 (Strategic Report and Directors’ Report) Regulations 2013, this article analyzes the regulatory requirements placed on carbon majors, and the climate change pledges and emissions of five UK-based carbon majors: BP, Royal Dutch Shell, BG Group, National Grid, and Centrica. The article concludes that the efforts to curb emissions in these carbon major entities are being subverted by company law, company theory and commercial norms such as shareholder wealth maximization.

Many multilateral environmental agreements have adopted differentiated rules for different countries, based on the recognition of the ‘common but differentiated responsibilities’ (CBDRs) of states. By establishing two rigid groups of countries with and without emissions reduction obligations, the intergovernmental climate regime represents the most extreme case of such differentiation. The regime has struggled to overcome this rigidity and the resulting political deadlock between developing and developed countries. Transnational climate governance (TCG) initiatives have emerged as an alternative to provide mitigation, adaptation or finance outside the multilateral process. By drawing on synergies between public and private actors, it is hoped that they overcome the paralysis of the intergovernmental process. Yet, they take place in the same world of unequal peers, with different levels of capacity and responsibility for climate change. This article investigates the extent to which such TCG initiatives reflect the CBDR principle. Do different types of initiative – involving different types of actor or with different climate-related goals – address differentiation in distinct ways? Does taking account of CBDRs affect the membership of transnational initiatives? This article explores these questions empirically by analyzing a sample of TCG initiatives in terms of how they include differential treatment of states and non-state members. It concludes that TCG initiatives address differentiation in a pragmatic way. Most frequently, they either offer participants flexibility in how to implement their commitments, or provide support to members from developing countries. Such support is, so far, still insufficient to address the limited involvement of developing country actors.

Since their inception, climate change negotiations have stalled because of the scope of parties’ mitigation responsibilities under the United Nations Framework Convention on Climate Change (UNFCCC). The concept of common but differentiated responsibilities and respective capabilities (CBDR-RC) became a core principle of the framework to ensure consensus on a global climate policy in 1992 and to promote differentiation. By letting each country assess its current responsibilities and capacities for climate mitigation through their nationally determined contributions (NDCs), the Paris Agreement has built on the principle of CBDR-RC and promoted self-differentiation. As the concept evolved, the role of emerging economies has been a particular focus of discussions. Academia is still grappling with the revised meaning of CBDR-RC and the newly introduced NDCs. This article contributes to the discussion by analyzing the role of emerging economies in climate governance through the lens of regional responsibility. In particular, it discusses how cooperation can be a more effective way to ensure differentiation, especially by distinguishing emerging economies from other developing countries with fewer capacities. The article uses the Amazon rainforest as a case study, discussing Brazil’s role within the region. Building on lessons from regional schemes that have successfully promoted climate mitigation, the article looks at the Amazon Cooperation Treaty Organization (ACTO) as an avenue for enhanced cooperation at the regional level.

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.