Temperature Targets and State Obligations on the Mitigation of Climate Change

The Supreme Court of the Netherlands in Urgenda held that States had a customary obligation to implement their ‘fair share’ in achieving the 2 °C temperature limitation target they had agreed upon. Yet, this article argues, the notion that States must adopt or implement mitigation action in line with temperature targets finds no support in treaty or customary law. States’ acceptance of temperature targets as a collective objective is relevant to interpreting the standard of due diligence applicable to mitigation obligations only inasmuch as this objective is actually reflected in consistent State practice. At present, temperature targets represent essentially an agreement on a direction of travel: the need for more mitigation action. Over time, the acceptance of this objective could facilitate further legal developments as States agree on particular implications of temperature targets and on a requirement that each of them acts consistently with its interpretation of these targets.