It is often said that the world is complex. Does this insight also apply to the field of global environmental governance? Have problems become more complex? Or are we merely observing the result of more information being available and applied to specific issues? And in turn, have our answers to sustainability challenges become more complex or are we witnessing more a congestion and general growth in governance approaches? This contribution will attempt to answer some of these questions by first arguing that we have seen a shift toward system perspectives in the way we perceive the problems and, second, outlining how our scientific concepts around environmental governance have shifted from being occupied with simple and stable units (e.g., international environmental regimes) to addressing interconnectivity and emergent properties of regime complexes as possible solutions to environmental issues.