Communicating Tail-Risk Credibly

Effectively communicating tail-risk can inform climate change preparation, but doing so crediblyis challenging––people find risk statements less credible when they include low probabilities.Across five experiments with lay people, elected policymakers, and legal experts, we explore theperceived credibility of tail-risk communication. First, we show that including tail-riskinformation reduces the perceived credibility of messages about global temperature change.Second, we show that this credibility penalty applies even when the audience agrees with thecommunicator’s probability estimates. Third, we identify low probabilities as contributors to tailrisk’slower credibility. Finally, we show that reframing tail-risk information in terms of highprobabilities boosts credibility (e.g., instead of indicating a 5% chance of more than 3.5ºCwarming, indicating a 95% chance of 3.5ºC warming or less), even when the communicator isadvocating for tail-risk mitigation. Overall, while it is hard to communicate tail-risk credibly, thecredibility cost can be reduced.