IPCC communicative practices: A linguistic comparison of the Summary for Policymakers 2007 and 2013
The present paper undertakes an analysis of language use in two so-called Summaries for policymakers (SPMs), published as part of the IPCC (Intergovernmental Panel on Climate Change) Assessment Reports 4 (AR4, 2007) and 5 (AR5, 2013). Through a comparative analysis, we investigate how scientific claims are conveyed through expressions indicating various levels of (un)certainty, through scalar systems established by the IPCC to indicate levels of likelihood, confidence and evidence, as well as through non-predefined linguistic means. We also consider to what extent contrasted claims may indicate a difference in argumentative emphasis in the two summaries, without diverging from the overall purpose of the IPCC: to present a consensual view on current climate knowledge. Further, the analysis assumes a textual perspective, investigating to what extent the summaries have a narrative structure with a clear storyline. The results show that, generally, the two SPMs adhere to the expressed purpose of the IPCC. However, there are differences indicating a strengthened basis for scientific certainty in the AR5-SPM. The narrative analysis discusses the lack of explicit reactions to the stated complications. The findings also point towards the need for further analyses to assess the reception of text layout and language use by policymakers.