If bioethics should care about the environment, this could be, among other ways, by reflecting on certain radical solutions, such as biomedical human engineering. In a recent article, Liao, Sandberg and Roache consider reducing human size through biomedical treatments in order to mitigate climate change. In this viewpoint, we point out that the various methods used to reduce human height, be they sophisticated tech­ nologies or mere undernutrition, seem all subject to highly undesirable consequences. This is to show that one (...) of the problems with Liao et al.’s account is that it does not provide us with an ethical framework com­ prehensive enough to balance these consequences with the problematic effects of climate change. In sum, we wish to draw from the discussion of this specific example a more general claim. This claim is that, even if we accept that human engineering per se is not problematic, we nevertheless need a more comprehensive ethical theory than the mere claim that climate change should be mitigated in order to assess the desirability of human engineering. (shrink)