How should scientists, science communicators, and educators respond to the growing prevalence in fake news and misinformation? This is particularly pertinent given the apparent decline in public reliance on facts and scientific evidence. The decades-old phenomenon of climate science denial offers insights into our current predicament. Science denial manifests the same characteristics of motivated reasoning as those observed in the post-truth movement. For example, one insight gleaned from research into science denial is that trying to convince people who reject scientific evidence is largely futile, and can be counterproductive. A more effective approach is inoculating the undecided majority against the influence of denialists misinformation. Consequently, psychological research into climate science denial may be instructive for scientists and educators grasping for communication approaches in the post-truth era.