Open Access

Frank Best, Anita Tang

• Climate change, a transnational issue, necessitates international collaboration for effective mitigation. Despite the progress achieved by the Paris Agreement of 2015, a significant milestone in global cooperation, its implementation remains a challenge for both the international community and individual countries. Because of the agreement's optional nature, there are significant differences in terms of the ambition and achievement levels among signatories. The European Union (EU) stands out because of its unique structure and common policies, yet there is a lack of empirical research into their impact on climate policy effectiveness. This paper aims to fill this gap by comparing the effectiveness of the implementation between EU and non-EU countries in terms of policy output, achieving climate targets and an economically sustainable transition. Quantitative regression models show no significant differences concerning policy output and the achievement of climate targets, while they demonstrate greater ambition and success in economically sustainable transition. Our findings contribute to a better understanding of effective climate policies, highlight the positive impact of EU leadership in this regard, and stress the importance of international cooperation.