Climatic Change

, Volume 113, Issue 2, pp 181–200

Effective communication of uncertainty in the IPCC reports

  • David V. Budescu
  • Han-Hui Por
  • Stephen B. Broomell

DOI: 10.1007/s10584-011-0330-3

Cite this article as:
Budescu, D.V., Por, HH. & Broomell, S.B. Climatic Change (2012) 113: 181. doi:10.1007/s10584-011-0330-3


The Intergovernmental Panel on Climate Change (IPCC) publishes periodical assessment reports informing policymakers and the public on issues relevant to the understanding of human induced climate change. The IPCC uses a set of 7 verbal descriptions of uncertainty, such as unlikely and very likely to convey the underlying imprecision of its forecasts and conclusions. We report results of an experiment comparing the effectiveness of communication using these words and their numerical counterparts. We show that the public consistently misinterprets the probabilistic statements in the IPCC report in a regressive fashion, and that there are large individual differences in the interpretation of these statements, which are associated with the respondents’ ideology and their views and beliefs about climate change issues. Most importantly our results suggest that using a dual (verbal—numerical) scale would be superior to the current mode of communication as it (a) increases the level of differentiation between the various terms, (b) increases the consistency of interpretation of these terms, and (c) increases the level of consistency with the IPCC guidelines. Most importantly, these positive effects are independent of the respondents’ ideological and environmental views.

Supplementary material

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • David V. Budescu
    • 1
  • Han-Hui Por
    • 1
  • Stephen B. Broomell
    • 2
    • 3
  1. 1.Department of PsychologyFordham UniversityBronxUSA
  2. 2.Department of Social and Decision SciencesCarnegie Mellon UniversityPittsburghUSA
  3. 3.College of Information Sciences and TechnologyPennsylvania State UniversityUniversity ParkUSA