How to Know the Global Ecological Crisis: The Epistemic Foundations of UNEP’s Global Environmental Outlook

Serving as the lead international organisation on global ecological questions, the United Nations Environment Programme (UNEP) regularly publishes the flagship Global Environmental Outlook (GEO), an expert-led evaluation of the state of planetary ecosystems. Although seven editions have been produced by now, little remains known about the bodies of knowledge on which UNEP draws for this exercise. Our paper reveals the epistemic foundations of UNEP’s work around the GEO by applying a combination of network and content analysis to the three latest editions: GEO-5 (2012), GEO-6 (2019) and GEO-7 (2025). Specifically, we delineate citation patterns from the three latest reports, which reveal what type of knowledge GEO experts reference in support of their assessments and recommendations. Moreover, we trace the intellectual and professional backgrounds of these experts themselves. In doing so, our paper speaks to recent studies on knowledge integration in international environmental policy and epistemic communities. We provide deeper insights into who gets selected to work on GEOs in the first place, and how they collate and recombine different sources of knowledge into a report that is designed to authoritatively represent the state of the art on planetary ecosystems. At a time of a rapidly unfolding degradation of the biosphere, paired with a strong recent greenlash, it is essential to better understand how UNEP ‘knows’ and narrates the global ecological crisis.