A scoping review of celebrity endorsement in environmental campaigns and evidence for its effectiveness

Abstract The use of celebrities in marketing campaigns is widespread globally, including in environmental conservation. Celebrity endorsements are pervasive, but there is limited evidence of their effectiveness. We conducted a review of celebrity‐endorsed environmental campaigns. We report on the extent to which celebrities have been used in these campaigns, whether evaluation of the endorsement has been conducted, and assess whether there is evidence that the celebrities achieved the objectives they set out to accomplish through their engagement. We searched the peer‐reviewed and grey literature in six languages from July 2018 to January 2019 and found 79 campaigns implemented in nine countries from 1976 to 2018. Two thirds of campaigns were implemented in China and reported in Chinese. Only four campaigns were evaluated, but none of the evaluations provided evidence of the effectiveness of celebrity endorsement. Evaluation focused instead on overall campaign outputs and outcomes. Claims of effectiveness were made, but the lack of measurable objectives, theory of change, outcome indicators, and critical evaluation renders it impossible to determine whether the outcomes achieved by the campaigns can be attributed to celebrity endorsement. It thus remains unclear whether celebrity endorsement can contribute to conservation efforts. It is essential for environmental practitioners and researchers to report the outcomes and lessons learned from celebrity endorsements to ensure that their future use in conservation marketing campaigns is evidence‐based, thereby improving conservation practice.