Influential scientists shape knowledge flows between science and IGO policy

Intergovernmental organizations (IGOs) increasingly rely on scientific evidence, yet the pathways through which scientific research enters policy remain opaque. By linking 230,737 scientific papers cited in IGO policy documents (2015-2023) to their authors and collaboration networks, we identify a small group of policy-influential scientists (PI-Sci) who dominate this knowledge flow. These scientists form tightly interconnected, internationally spanning co-authorship networks and achieve policy citations shortly after publication, a distinctive feature of cumulative advantage at the science-policy interface. The concentration of influence varies by field: tightly clustered in established domains like climate modeling, and more dispersed in emerging areas like AI governance. Many PI-Sci serve on high-level advisory bodies (e.g., IPCC), and major IGOs frequently co-cite the same PI-Sci papers, indicating synchronized knowledge diffusion through shared expert networks. These findings reveal how network structure and elite brokerage shape the translation of research into global policy, highlighting opportunities to broaden the scope of knowledge that informs policy.