Text-mining the signals of climate change doubt

Climate scientists overwhelmingly agree that the Earth is getting warmer and that the rise in average global temperature is predominantly due to human activity. Yet a significant proportion of the American public, as well as a considerable number of legislators in the U.S. Congress, continue to reject the "consensus view." While the source of the disagreement is varied, one prominent explanation centres on the activities of a coordinated and well-funded countermovement of climate sceptics. This study contributes to the literature on organized climate scepticism by providing the first systematic overview of conservative think tank sceptical discourse in nearly 15 years. Specifically, we (1) compile the largest corpus of contrarian literature to date, collecting over 16,000 documents from 19 organizations over the period 1998-2013; (2) introduce a methodology to measure key themes in the corpus which scales to the substantial increase in content generated by conservative think tanks over the past decade; and (3) leverage this new methodology to shed light on the relative prevalence of science- and policy-related discussion among conservative think tanks. We find little support for the claim that "the era of science denial is over"-instead, discussion of climate science has generally increased over the sample period. (C) 2015 Elsevier Ltd. All rights reserved.