The medical profession is observing a rising number of calls to action considering the threat that climate change poses to global human health. Theory-led bioethical analyses of the scope and weight of physicians' normative duty towards climate protection and its conflict with individual patient care are currently scarce. This article offers an analysis of the normative issues at stake by using Korsgaard's neo-Kantian moral account of practical identities. We begin by showing the case of physicians' duty to climate protection, before we succinctly introduce Korsgaard's account. We subsequently show how the duty to climate protection can follow from physicians' identity of being a healthcare professional. We structure conflicts between individual patient care and climate protection, and show how a transformation in physicians' professional ethos is possible and what mechanisms could be used for doing so. An important limit of our analysis is that we mainly address the level of individual physicians and their practical identities, leaving out important measures to respond to climate change at the mesolevels and macrolevels of healthcare institutions and systems, respectively.