Accelerated changes to the planet have created novel spaces to re-imagine the boundaries and foci of environmental health research. Climate change, mass species extinction, ocean acidification, biogeochemical disturbance, and other emergent environmental issues have precipitated new population health perspectives, including, but not limited to, one health, ecohealth, and planetary health. These perspectives, while nuanced, all attempt to reconcile broad global challenges with localized health impacts by attending to the reciprocal relationships between the health of ecosystems, animals, and humans. While such (...) innovation is to be encouraged, we argue that a more comprehensive engagement with the ethics of these emerging fields of inquiry will add value in terms of the significance and impact of associated interventions. In this contribution, we highlight how the concept of spatial and temporal scale can be usefully deployed to shed light on a variety of ethical issues common to emerging environmental health perspectives, and that the potential of scalar analysis implicit to van Potter’s conceptualization of bioethics has yet to be fully appreciated. Specifically, we identify how scale interacts with key ethical issues that require consideration and clarification by one health, ecohealth, and planetary health researchers and practitioners to enhance the effectiveness of research and practice, including justice and governance. (shrink)