This article challenges assumptions about how domestic politics shape international climate cooperation. Using new data from UN negotiations, I demonstrate that a sector's trade exposure plays a crucial role in determining firm-level opposition to climate agreements—especially when pollution levels are high.

• Key finding: Trade-exposed industries with high emissions strongly oppose climate regulations due to absorption costs and competitive pressures.

• Country analysis shows strong correlations between government preferences for cooperation and national reliance on tradable high-emission sectors.

• This research reveals that sectoral dynamics outweigh simple cost-benefit calculations in environmental policymaking.