Initiated in 2002, the International Environmental Agreements Data Base (IEADB) catalogs the texts, memberships, and design features of over 3,000 multilateral and bilateral environmental agreements. Using IEADB data, we create a comprehensive review of the evolution of international environmental law, including how the number, subjects, and state memberships in IEAs have changed over time. By providing IEA texts, the IEADB helps scholars identify and systematically code IEA design features. We review scholarship derived from the IEADB on international environmental governance, including insights into IEA membership, formation, and design as well as the deeper structure of international environmental law. We note the IEADB’s value as a teaching tool to promote undergraduate and graduate teaching and research. The IEADB’s structure and content opens up both broad research realms and specific research questions, and facilitates the ability of scholars to use the IEADB to answer those questions of greatest interest to them.

In the context of increasing fragmentation and functional differentiation in international governance, new environmental regionalism represents a recent trend involving initiatives that seek to territorialize environmental governance at the level of transboundary ecoregions, such as mountain ranges or river basins. This article examines the implications of this trend for sustainable development, which is defined here as a procedural norm for reconciling the tradeoffs between environmental, economic, and social dimensions of wellbeing. This article (1) traces arguments concerning the origins of functional differentiation to research on European state-making; (2) offers two complementary perspectives that generate insights into sustainable development at the transboundary level, one focusing on the intersection of multiple and overlapping functional spaces, and the other focusing on regionalization as the domestic manifestation of regional themes; and (3) illustrates the significance of these perspectives in the case of the European Alps. The article suggests that the Alps serve both as the bounded object of an international legally binding agreement asking its signatories to formalize sustainable development, and as the intersection of multiple overlapping functional spaces. It lends support to claims about the link between rescaling and functional differentiation, but demonstrates that a sympathetic critique of new environmental regionalism need not conclude that the phenomenon exacerbates the fragmentation of international governance.

Global environmental governance is growing increasingly complex and recent scholarship and practice raise a number of questions about the continued feasibility of negotiating and implementing an ever-larger set of global environmental agreements. In the search for alternative conceptual models and normative orders, regional environmental governance (REG) is (re)emerging as a significant phenomenon in theory and practice. Although environmental cooperation has historically been more prevalent at the regional than at the global level, and has informed much of what we know today about international environmental cooperation, REG has been a neglected topic in the scholarly literature on international relations and international environmental politics. This introduction to the special issue situates theoretical arguments linked to REG in the broader literature, including the nature of regions, the location of regions in multilevel governance, and the normative arguments advanced for and against regional orders. It provides an overview of empirical work; offers quantitative evidence of REG's global distribution; advances a typology of REG for future research; and introduces the collection of research articles and commentaries through the lens of three themes: form and function, multilevel governance, and participation.