Uncertainty Communication and Climate Changes, 2017

IPCC has developed detailed guidelines for how to express uncertainties in the field of climate change in a consistent way. At the same time, recent cross-national studies have demonstrated extensive misinterpretations of recommended terms. The aim of the present project is to go beyond these demonstrations and uncover how people perceive and understand uncertainty in climatic forecasts, and on this basis provide communicators with informed advice on how their message will be read by different audiences. The project has three parts. (1) Subproject 1 focuses on people's perceptions of wide vs. narrow uncertainty intervals (range estimates) and upper vs. lower limit estimates. The studies are based on prior research done by Teigen, Jørgensen, Halberg, and Fostervold, indicating (a) a preference for overly narrow intervals, and (b) framing effects of single-limit intervals (different pragmatic implications of maximum vs. minimum estimates). (2) Subproject 2 concerns the interpretations of verbal probabilities, derived from the "which outcome approach", recently developed by Teigen, Juanchich, Filkuková and others. Their studies suggest that predictions involving what will happen, or is certain, typically describe minimum outcomes, and what can happen, or is possible, typically describe maximum outcomes. The current project asked how people interpret such statements for positive versus negative outcomes in a context of climate change. (3) These part projects suggest several overlapping issues, including a preoccupation with extreme outcomes, a preference for numeric vs. verbal estimates, the role of numeracy, and which kind of probability concepts people have in mind. Findings provide insights into lay interpretations of uncertainty in scientific forecasts, and suggests guidelines for how uncertain effects of climate change should be communicated in a reliable way, thereby preparing the public and policy makers for societal consequences of climate changes.

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