In his Review of books by James Hansen and Stephen Schneider (Nature 464, 352–353; 2010), Roger Pielke Jr misguidedly implies that it is undemocratic for climate scientists to call for action against climate change in the name of science.

The normative assumptions underlying climate-change policy recommendations receive much less public attention than the scientific facts that fuel policy deliberation. The debate proceeds as though there is a common moral sense that we can rely on when arguing about climate-policy issues. Consequently, it seems as if disagreement over policy conclusions can stem only from disagreement about scientific facts. This leads to an absurd situation in which people with no understanding of the scientific arguments feel compelled to challenge the science.

It might be helpful to pay more attention to the normative issues underlying the climate discourse, for example by identifying the disagreement about the relevance of suffering in distant places or times, or the role of uncertainty in normative assessments.