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Differentiation in the NDCs to the Paris Agreement – A Legal and Empirical Analysis

Ulrike Will


This paper explains how the 193 first nationally determined contributions (NDCs) specify the vague criteria of differentiation of the Paris Agreement as subsequent practice (Article 31(3)(b) VCLT). Combining a legal analysis with an original, systematic empirical analysis of the NDCs, the paper provides transparency without judgment respecting the self-defined approach to differentiation of the Paris Agreement. Operationalising criteria of differentiation that are representatively recognised and affect subsequent practice are the term ‘fairness’, absolute emissions (most frequently specified by unconditional quantified absolute emissions targets or the respective share in global or regional emissions), and the emissions per capita (the most common parameter to define fairness). However, the open weight of these criteria compared to other, less uniformly recognised criteria of differentiation and the dominance of the individualistic term ‘fairness’ make clear that the criteria of differentiation are only slightly narrowed; the self-defined approach to differentiation still dominates. Based on the most recognised criteria of the NDCs, the paper suggests an open-ended reporting table to structure the criteria of differentiation, facilitate their comparison, and enhance their transparency.

Ulrike Will, M.A., is a postdoc researcher in the project ‘Incentives, Fairness and Compliance in International Environmental Agreements (InFairCom)’ at Leipzig University of Applied Sciences (HTWK). She specialises in international climate law and international economic law. For correspondence: <>. I would like to thank Dr. Marius Alt, Dr. Robert Garthoff, Dr. Claire Gavard, Prof. Dr. Cornelia Manger-Nestler, Prof. Dr. Bodo Sturm, and an anonymous referee for helpful comments on previous drafts of that article. All remaining errors remain mine. This contribution was written in the context of the InFairCom project in the funding line ‘Economics of Climate Change’ supported by the German Federal Ministry of Education and Research (grant no. 01LA1825C).


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