Stance in climate science: A diachronic analysis of epistemic stance features in IPCC physical science reports

This diachronic corpus-based analysis investigates the use of epistemic stance devices inreports from the United Nations’ Intergovernmental Panel on Climate Change (IPCC)from the date of its first report on the physical science of climate change in 1990 to itssixth contribution in 2021. Applying the framework of stance (Biber & Finegan, 1989),the study focuses upon changes in the use of the epistemic stance markers of modal verbsand adverbs across the approximately 30-year period. To empirically measure thestrength of trends in the use of these stance devices, Kendall’s Tau correlation coefficientwas calculated for each item using their normalized frequencies from the six reports.Analysis displayed that the use of modal verbs has consistently decreased across thisperiod of time in which the scientific consensus regarding the anthropogenic origins ofclimate change expanded and solidified. Additionally, of the greater than twenty stanceadverbs displaying consistent use trajectories across the period, the majority of theseitems were emphatic adverbs declining in use.