Justice is emerging as a lens for assessing and comparing scenarios generated by global Integrated Assessment Models (IAMs) for inclusion in Intergovernmental Panel on Climate Change reports. We aim to identify analytical tools to incorporate justice into IAMs. Drawing upon 39 interviews with a multi-disciplinary range of experts embodying gradients of involvement with IAMs and justice-informed assessment, we map three prospective avenues – ranging from working within the global IAMs, to improving points of access to global IAMs, to refining the role of global IAMs in a broader landscape of possible methods and tools. Our analysis is reflective of broader discussions and criticism of IAMs but highlights some specific nuances pertaining to justice. We depict the debates on whether and how justice was incorporated in IAMs in the past and highlight some of the most contested points.