Party Movements, Environmental Pollution, and Electoral Systems

External pressures and institutions alter political parties’ ideological positions. We examine the impact of the interactive relationship between environmental problems and electoral systems on party movements. On the one hand, we hypothesize that stronger environmental problems provide incentives for all parties to move to more green positions. On the other hand, the party system is divided. Environmental-positive parties move to more green positions while environmental-skeptical parties move to the opposite direction. Anti-green/economic growth-positive positions become more attractive for parties if environmental pressure becomes more important. To examine this empirical puzzle our analysis uses individual party data for 36 countries and about 300 parties from 1944 to 2016. Our results confirms the first argument but only under an appropriated institutional framework. Cox (1990) shows that electoral systems per se provide centrifugal and centripetal incentives for political parties. Therefore, both factors interact with each other, thereby jointly shaping party positions. We show that increasing environmental pollution only enact an ideological move towards more green positions when parties compete in a proportional electoral systems. Our results on the joint effect of environmental pollution and electoral institutions suggest that only under proportional electoral systems parties take positions closer to the green ideological margins. If majoritarian systems are used, parties stay on their former ideological position independently of the environmental pollution extent.