In the last decade, the “storyline” approach has been introduced and developed in the subfield of attribution and detection in climate studies. In spite of its merits, it has been met with harsh criticism, especially from advocates of probabilistic approaches. The overall aim of UN3 is to explore and exploit the symbiotic relations between the storyline approach and the philosophy of scientific understanding, to foster the legitimation of the former and advance internal philosophical debates in the latter. UN3 is organized into three research work packages (WPs) with a specific objective. WP1 investigates the “factivity” of storyline-based understanding. Its specific objective is to characterize and evaluate storyline-based scientific understanding, emphasising its complementarities with and divergences from probabilistic understanding, particularly in terms of their factivity. WP2 investigates the “effectiveness” of storyline- based understanding. Its specific objective is to assess the effectiveness/factivity ratio of storyline-based understanding in successful decision-making under deep uncertainty, particularly in terms of informing robust and/or adaptive strategies and exploiting their relations. WP3 investigates the “transdisciplinarity” of storyline-based understanding. Its specific objective is to identify, characterize, and develop transdisciplinary means in which storyline-based understanding may be advanced by local knowledge and, in turn, advance epistemic justice in climate science, particularly in terms of conveying actionable knowledge. The overall methodology is inter- and transdisciplinary, involving theoretical and empirical components, and including collaborations with academic researchers from various centres and with non-academic stakeholders. UN3 will be conducted at Politecnico di Milano with Prof. Giovanni Valente as supervisor and Prof. Massimo Tavoni as co-supervisor. A secondment is planned at TU Delft, with Prof. Behnam Taebi as host.