This chapter provides a critical commentary of Article 2 of the Paris Agreement. Article 2 is the key provision of the much-lauded Paris Agreement, setting its key ‘target temperature’ – “well below 2°C” – and giving a novel degree of prominent to climate adaptation and finance. Although ostensibly focusing on its aims, objectives and principles, the paper argues that Article 2 is also the product of questionable compromises that may well undermine the core objectives of the entire climate regime. The language of Article has made more challenging the task of enforcing climate law, and distorted the concept of differentiation. These weaknesses, now hardwired into the international framework for climate action, create a legal void into which national and regional processes of constitutionalism must now step. The paper sets out a framework for the creation of credible commitments in national law, and their attainment. It remains to be seen whether systems of constitutional law can bear this weight placed upon them by an inadequate international regime. NB: The paper also addresses the implications of the UK Plan B/Heathrow airport decision