Intergovernmental organizations (IOs) increasingly promote global citizenship education (GCE) and related topics. This paper analyses the body of scholarship on GCE that focuses on teachers and interprets the development of environment-related education (ERE) within the GCE discourse. Using a novel, data-rich methodology employing Natural Language Processing and Social Network Analysis, we trace how ERE is represented within the GCE scholarship and how this representation evolved during the last ten years. We argue that ERE topics have become increasingly prominent within the GCE discourse, as a tendency toward subject-specific discourse emerged in GCE, heavily influenced by intergovernmental organizations' policies. It is important to trace and understand such transformations, given their possible influence on curricular development and classroom experiences. Future research directions and possible practical implications are discussed.