External dimensions of European environmental policy: An analysis of environmental treaty ratification by third states

The European Union has become an important leader in international environmental affairs – particularly through the negotiation of multilateral environmental agreements (MEAs) with favourable terms. In this article, EU environmental leadership is studied from a new perspective, focusing on the ratification stage of environmental regime formation. Specifically, it investigates whether the EU is also capable of motivating third states to join its preferred MEAs. It is argued that third states join the EU's preferred MEAs to signal their compliance with EU environmental standards in an effort to become eligible for various rewards that the EU could potentially offer, including a credible membership perspective, access to its lucrative markets, and aid and assistance. The argument is tested by examining the ratification behaviour of 25 non‐EU Member States with regard to all 21 MEAs negotiated under the auspices of the United Nations Economic Commission for Europe (UNECE). The results provide robust support for the theory that EU rewards motivate third states to ratify these treaties. The results withstand a number of statistical tests, even when alternative explanatory factors such as trade intensities, transnational communication and geographic proximity are controlled for. The study is the first large‐scale demonstration of the EU's external influence at the ratification stage of environmental regime formation. By identifying three different channels of EU influence, the research permits a more refined understanding of the EU's role as a promoter of environmental protection standards.