The challenge for policymakers at COP30 is not to reach universal agreement on the exact ‘price’ of carbon, but to build rules that function amid disagreement in a divided world. This column argues that trade must now serve as a channel for managing uncertainty, not amplifying it, and outlines how trade rules can be made responsive to environmental costs – by distributing policy authority across institutions, leveraging ‘coalitions of the willing’, and aligning finance with principles of