This book has roots in a research seminar on international environmental issues that I have taught for several years at the Paul H. Nitze School of Advanced International Studies, The Johns Hopkins University. The seminar members have been graduate students of international relations with varied training in economics. My contribution has been to provide enough theory, drawn from international and environmental economics, to provide a coherent analytical framework for understanding environmental issues, especially in an international context. Their contributions have mainly been policyoriented research, sometimes using economic concepts and tools and sometimes using legal, institutional, or political approaches. This combination of theory and policy has been successful in the classroom, and I hope it will carry over in the book. My experience is that although the merging of environmental and international economics is rather new, and at many points is breaking new ground, a clear exposition of basic principles and concepts helps bring some analytical rigor to what are frequently confused public policy debates.

Interest in international environmental issues among students and the general public has increased greatly in recent years for several reasons. Some global environmental threats such as climate change and the thinning of the atmospheric ozone shield, although not absent or unknown in the 1970s, have taken on greater urgency and have moved up the international policy agenda.