Improving Communication of Uncertainty in the Reports of the Intergovernmental Panel on Climate Change

• Published in: Psychological science Vol. 20; no. 3; pp. 299 - 308
• Main Authors: Budesen, David V., Broomell, Stephen, Por, Han-Hui
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA Wiley Periodicals 01-03-2009; SAGE Publications; SAGE PUBLICATIONS, INC
• Subjects: Adolescent; Adult; Aged; Analytical forecasting; Climate; Climate change; Climate models; Cognition & reasoning; Communication; Confusion; Congresses as Topic; Control groups; Experimental psychology; Female; Government; Greenhouse effect; Humans; Intergovernmental organizations; Interinstitutional Relations; International environmental cooperation; Judgment; Male; Middle Aged; Misinterpretation; Mitigation; Policy making; Psychological factors; Psychology; Recommendations; Sea level; Sociological analysis; Spoken communication; Statistical median; Uncertainty; Young Adult
• ISSN: 0956-7976; 1467-9280
• DOI: 10.1111/j.1467-9280.2009.02284.x

The Intergovernmental Panel on Carnate Change (IPCC) assesses information relevant to the understanding of climate change and explores options for adaptation and mitigation. The IPCC reports communicate uncertainty by using a set of probability terms accompanied by global interpretational guidelines. The judgment literature indicates that there are large differences in the way people understand such phrases, and that their use may lead to confusion and errors in communication. We conducted an experiment in which subjects read sentences from the 2007 IPCC report and assigned numerical values to the probability terms. The respondents' judgments deviated significantly from the IPCC guidelines, even when the respondents had access to these guidelines. These results suggest that the method used by the IPCC is likely to convey levels of imprecision that are too high. We propose an alternative form of communicating uncertainty, illustrate its effectiveness, and suggest several additional ways to improve the communication of uncertainty.