"As Earth system sciences increasingly emphasize the production of actionable data to inform policy, community action, and funding decisions, the consequences of researchers’ methodological choices become more apparent. Epistemic risk refers to the possibility that assumptions, limitations, or trade-offs in the research process will lead to findings that are inadequate for their intended purpose. A second form of epistemic risk emerges when decision-makers use scientific products without fully understanding their underlying assumptions or limitations, potentially applying them in inappropriate contexts and producing unintended outcomes. In this essay, we examine epistemic risks that emerged across five community-based research projects conducted as part of a multiyear effort at the U.S. National Science Foundation National Center for Atmospheric Research to develop actionable Earth system data and tools. Our cross-case analysis shows that while actionable science makes epistemic risks more visible, it also creates opportunities to address them. Community-based and convergence research approaches enable users to participate in methodological decisions about acceptable assumptions, uncertainties, and trade-offs. These collaborative processes foster more effective, multidirectional communication about uncertainty and data limitations, allowing both researchers and decision-makers to make more informed choices and improving the fitness of scientific products for decision-making." #EpistemicRisk #PhilosophyOfScience https://journals.ametsoc.org/view/journals/bams/107/9/BAMS-D-24-0218.1.xml