Partisan and Institutional Sources of International Environmental Cooperation

International politics has become increasingly concerned with environmental problems. Over the last few decades, numerous conferences and negotiations have produced international environmental agreements (IEAs) that cover various issues of environmental protection. Against this background, scholarly interest in the dynamics of state participation in IEAs has increased significantly. Particular attention has been devoted to domestic-level factors that either promote or hinder states to join environmental treaties. Following this line of research, the present study examines the impact of political parties and domestic institutions on the propensity of democratic countries to join IEAs. While case studies of environmental treaties frequently highlight domestic struggles over ratification involving different partisan actors and institutional settings, large-n studies have so far only devoted cursory attention to these factors. It is this study’s aim to contribute to filling this gap. Paying close attention to domestic ratification procedures, the study uses partisan politics and veto player theory to develop more actor-centered explanations of international environmental cooperation and tests them in a large n-setting. The analyses are based on the ratification behavior of 23 advanced democracies vis-à-vis 60 IEAs from 1971 through 2003. The results show that governments and veto players attaching higher priority to environmental protection significantly increase the likelihood of ratifications. These results support a partisan politics explanation of international environmental cooperation that has not received much attention so far. Thereby, the study seeks to add to both the debate on international environmental cooperation and to a broader basis for domestic-level explanations of international politics in general.