Dana Nuccitelli

Quantifying the consensus on anthropogenic global warming in the scientific literature

We analyze the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11 944 climate abstracts from 1991‐2011 matching the topics ‘global climate change’ or ‘global warming’. We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming. In a second phase of this study, we invited authors to rate their own papers. Compared to abstract ratings, a smaller percentage of self-rated papers expressed no position on AGW (35.5%). Among self-rated papers expressing a position on AGW, 97.2% endorsed the consensus. For both abstract ratings and authors’ self-ratings, the percentage of endorsements among papers expressing a position on AGW marginally increased over time. Our analysis indicates that the number of papers rejecting the consensus on AGW is a vanishingly small proportion of the published research.

Does It Matter if the Consensus on Anthropogenic Global Warming Is 97% or 99.99%?:

Cook et al. reported a 97% scientific consensus on anthropogenic global warming (AGW), based on a study of 11,944 abstracts in peer-reviewed science journals. Powell claims that the Cook et al. methodology was flawed and that the true consensus is virtually unanimous at 99.99%. Powell’s method underestimates the level of disagreement because it relies on finding explicit rejection statements as well as the assumption that abstracts without a stated position endorse the consensus. Cook et al.’s survey of the papers’ authors revealed that papers may express disagreement with AGW despite the absence of a rejection statement in the abstract. Surveys reveal a large gap between the public perception of the degree of scientific consensus on AGW and reality. We argue that it is the size of this gap, rather than the small difference between 97% and 99.99%, that matters in communicating the true state of scientific opinion to the public.

Comment on "Cosmic-ray-driven reaction and greenhouse effect of halogenated molecules: Culprits for atmospheric ozone depletion and global climate change"

Lu (2013) (L13) argued that solar effects and anthropogenic halogenated gases can explain most of the observed warming of global mean surface air temperatures since 1850, with virtually no contribution from atmospheric carbon dioxide (CO2) concentrations. Here we show that this conclusion is based on assumptions about the saturation of the CO2-induced greenhouse effect that have been experimentally falsified. L13 also confuses equilibrium and transient response, and relies on data sources that have been superseeded due to known inaccuracies. Furthermore, the statistical approach of sequential linear regression artificially shifts variance onto the first predictor. L13s artificial choice of regression order and neglect of other relevant data is the fundamental cause of the incorrect main conclusion. Consideration of more modern data and a more parsimonious multiple regression model leads to contradiction with L13s statistical results. Finally, the correlation arguments in L13 are falsified by considering...