In this article we consider the economic ideas that have influenced climate disruption law both in the USA and the EU. Although economic thought has led to the adoption of ‘market-based’ mechanisms in both places, its impact has been different: it created regulatory inertia in the USA, and green leadership in the EU—at least with respect to responding to climate disruption. We argue that different culture-specific economic conceptions about appropriate policy and policy analysis may help explain this divergence, thereby illustrating both various economic ideas and their distinct impact on climate law, as well as the need for environmental lawyers to engage with a discipline outside their own.