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Linguistic analysis of IPCC summaries for policymakers and associated coverage


The Intergovernmental Panel on Climate Change (IPCC) Summary for Policymakers (SPM) is the most widely read section of IPCC reports and the main springboard for the communication of its assessment reports. Previous studies have shown that communicating IPCC findings to a variety of scientific and non-scientific audiences presents significant challenges to both the IPCC and the mass media. Here, we employ widely established sentiment analysis tools and readability metrics to explore the extent to which information published by the IPCC differs from the presentation of respective findings in the popular and scientific media between 1990 and 2014. IPCC SPMs clearly stand out in terms of low readability, which has remained relatively constant despite the IPCC’s efforts to consolidate and readjust its communications policy. In contrast, scientific and quality newspaper coverage has become increasingly readable and emotive. Our findings reveal easy gains that could be achieved in making SPMs more accessible for non-scientific audiences.

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Figure 1: Box-and-whisker plots showing FRE scores for IPCC SPMs and scientific publications (Nature and Science) as well as quality (The Independent, The Times, New York Times, Washington Post) and tabloid newspapers (The Mirror, The Sun, Daily News) related to the launch of IPCC assessment reports from 1990 to 2014.
Figure 2: Mean FRE scores over time for IPCC SPMs and scientific publications, as well as quality and tabloid newspapers related to the launch of IPCC assessment reports from 1990 to 2014.
Figure 3: Comparison of FRE scores for pre- and post-plenary AR4 and AR5 IPCC SPMs as well as TSs.
Figure 4: Box-and-whisker plots displaying DICTION optimism scores for IPCC SPMs, scientific publications, quality and tabloid newspapers related to the launch of IPCC assessment reports from 1990 to 2014.
Figure 5: Mean DICTION optimism Z-scores (with standard errors) of different types of media compared to the IPCC SPMs mean over time.


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We thank E. Ioannou and A. Gibson for valuable research assistance. We also thank participants of the workshop ‘Media, the IPCC and the Cultural Politics of Climate Change’ held at the University of Exeter in May 2014 for their comments on an earlier version of the manuscript. S.D. is supported by the European Research Council under the 7th Framework Programme (FP7/2007-2013)/ERC Grant agreement no. 284369 and by the UK Economic and Social Research Council (ESRC) for the Centre for Climate Change Economics and Policy (CCCEP).

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R.B. and B.M.-S. conceived the study. R.B., S.D. and G.N. designed the study. All co-authors contributed to analysis and writing.

Corresponding author

Correspondence to Ralf Barkemeyer.

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The authors declare no competing financial interests.

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Barkemeyer, R., Dessai, S., Monge-Sanz, B. et al. Linguistic analysis of IPCC summaries for policymakers and associated coverage. Nature Clim Change 6, 311–316 (2016).

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