Abstract

As a legal concept, emission budgets can be functionalized in several ways for structuring and activating climate protection responsibility. This potential, however, has only gradually been realized by climate change law. The article retraces the evolution of climate change law in this respect and identifies the central functions emission budgets are going to play in its future. Three development stages of climate change law can be distinguished: At the first stage, the legal allocation of emission budgets primarily served to concretize and transparently assign the reduction responsibility of individual countries and emitters. The quantification of individual reduction obligations creates both the basis for effective monitoring of the actual fulfillment of reduction responsibility as well as the basis for efficiency-promoting forms of cooperation. During the second stage, climate change law started to develop into a more comprehensive form of transformative law, which transcends punctual mitigation strategies and aims at the comprehensive structural transformation of society towards climate neutrality. Starting with the UK Climate Change Act 2008, national climate laws are enacted to structure the transformation in a coordinated manner. Emission budgets are now being additionally used to structure the reduction responsibilities of the individual sectors more comprehensively in the dimension of time through transformation pathways. Furthermore, they serve as a means of coordination between the different sectors. It is only in the current third phase of development, however, that climate change law is beginning to respond to the scientific insight that the temperature target, as laid down in the Paris Agreement, can only be achieved by relating the reduction paths back to a corresponding global emissions budget derived from the temperature target. The article shows how climate change law at the European and national level is developing initial approaches for such a conceptual reconnection, even in the absence of an international agreement about the right criteria for the distribution of the residual global emission budget. It concludes with an analysis of the administrative law challenges of implementing emissions budgets and highlights characteristics of climate law as transformative law.