Complex systems are systems that display unique properties such as emergence and self-organization. Their behavior is inherently unpredictable due to nonlinear relationships between interdependent parts and processes. This makes complex systems different from systems that are just complicated by possessing many parts. A key variable is the complexity of global governance systems, for which there are several notable approaches to operationalization. An agency-oriented approach, on the one hand, seeks to identify when the complexity of a governance system reaches beyond the cognitive capacity of agents operating therein. A structure-oriented approach, on the other hand, seeks to measure complexity as a quality inherent in a governance system....