This thesis examines the question of environmental dilemmas from both a local and a global perspective. It explores the open question of cooperation in the climate commons and provides evidence in favor of a key role of trust in spurring cooperation in global dilemmas. Given the potential for cooperation in both local and global environmental dilemmas, this thesis explores the rationales for the limited diffusion of environmental taxes. It encompasses the issues of effectiveness and public acceptability in local and global situations and concludes that what most likely hampers the implementation of environmental taxes is the general public’s perception of ineffectiveness rather than any empirical ineffectiveness. Finally, it provides new insights on how to overcome this barrier to effective policymaking tackling local and global externalities.