The presence of nonzero conjectural variations in pollution abatement and output make emission taxes less effective with respect to reducing emissions. This has implications for the characterization of the optimal emission tax, particularly in an international context where there are large asymmetries in pollution intensities. A higher degree of collusion in output between polluting firms results in higher emissions taxes in the non-cooperative equilibrium. In contrast, a higher degree of collusion in abatement between polluting firms results in lower emissions taxes in the non-cooperative equilibrium. These results rely on the presence of nonzero conjectural variations and large asymmetries in pollution intensities across countries. The analysis is relevant to the design of international environmental policy, including cases where countries face increasing global competition and damages from rising global emissions.

污染减排和产出中存在的非零推测变化使得排放税在减少排放方面的有效性降低。这对最佳排放税的表征具有重要意义，特别是在污染强度严重不对称的国际背景下。污染企业之间更高程度的产出勾结导致非合作均衡中更高的排放税。相比之下，污染企业之间较高程度的共谋减排会导致非合作均衡中的排放税较低。这些结果依赖于存在的非零推测变化和各国污染强度的巨大不对称性。该分析与国际环境政策的设计有关，