The EU has set itself an ambitious agenda to tackle climate change. Competition policy, including merger review, is called upon to play its part. Based on an analysis of the Commission’s practice, this chapter identifies the key framework issues for the consideration of climate change concerns in merger control and the parameters for addressing them under the EU Merger Regulation and in the light of the European Treaties. One focus will be on the implications of a differentiated allocation of regulatory powers across different policy areas. It is argued that a distinction must be made between scenarios in which the climate change argument is used to justify stricter or conceptually extended merger control and those in which it is argued that merger control should need to be relaxed for climate change reasons. With regard to the first scenario, shifts of a normative nature can be observed and are indeed called for, but these take place within the consumer welfare paradigm and it remains the case that the protection of competition is the sole overriding principle of the EU Merger Regulation. In contrast, in the second scenario, merger-specific ‘green’ efficiencies need to be considered even if they are not captured by the consumer welfare paradigm.