The best or worst is yet to come: how optimism and pessimism shape beliefs about future climate projections among the general public and experts

Effective communication of uncertainty in climate projections has important implications for planning and decision-making for individuals and policy makers. We examine, for the first time, how both the general public (n=1099) and experts (n=82) respond to the irreducible uncertainty presented by different Greenhouse Gas emission pathways and how this uncertainty affects people’s interpretation of projected future temperature ranges (e.g., 4°C to 7.2°C by 2100). Our results suggest that people find it difficult to disentangle their prior beliefs about the likelihood of different climate futures from objective scientific statements about projected temperature ranges. We identify both Optimists and Pessimists whose beliefs about the most likely future scenarios influence their interpretation of identical numerical ranges. We also find that age, behavioural willingness and climate anxiety were predictive of being an Optimist, whereas personal experience with climate change predicted being a Pessimist. Together our results suggest that simply increasing the discourse around potential climate futures may help people to understand the uncertainty in climate projections and could shift both their priors and their behaviours.