The Turn to Metrics in International Environmental Law

The UN’s Sustainable Development Goals (SDGs) were adopted in part to inject dynamism into international environmental governance that law is perceived to lack. In fact, the performance metrics on which the SDGs are predicated have long been an important component of international environmental regimes, as an analysis of the climate change regime clearly illustrates. I argue that the integration of metrics into legal regimes holds distinct advantages over the SDG approach, in which metrics are developed and implemented with little or no contribution by legal normativity. The Paris Agreement illustrates how legal norms and metrics can work together to generate equilibrium between instrumentality and legality, scientific and legal modes of reasoning, and dynamism in the face of rapid ecological change and scientific understandings, and the stability provided by normative approaches.