This commentary analyzes the ontological character of the United Nations’ Millennium Ecosystem Assessment (2005) and its attempt to imagine business-as-usual and transformative human-environmental futures. The Millennium Ecosystem Assessment (MA) constitutes the first and most significant attempt by an international political body to incorporate environmental concerns into the field of imaginative scenario building. In addition to its lengthy report on the threatened status of planetary ecosystems, the MA contains extensive “future scenarios” that imagine how human-environmental relations might unfold over the course of the twenty-first century. These scenarios arise out of the lineage of military scenarios generated during the Cold War, and continue to inform UN assessments in the present. This commentary explores how a politico-military concern for security informs the framework of the scenarios, and limits how the MA characterizes the fundamental human act of narration. In the process, the commentary explores alternative ontologies of narration and how these may lead to more transformative narratological interventions.