Environmental skepticism denies the reality and importance of mainstream global environmental problems. However, its most important challenges are in its civic claims which receive much less attention. These civic claims defend the basis of ethical authority of the dominant social paradigm. The article explains how political values determine what skeptics count as a problem. One such value described is "deep anthropocentrism," or the attempt to split human society from non-human nature and reject ecology as a legitimate field of ethical concern. This bias frames what skeptics consider legitimate knowledge. The paper then argues that the contemporary conservative countermovement has marshaled environmental skepticism to function as a rearguard for a maladaptive set of core values that resist public efforts to address global environmental sustainability. As such, the paper normatively argues that environmental skepticism is a significant threat to efforts to achieve sustainability faced by human societies in a globalizing world.