Stronger, sooner, and more certain climate change: A link between certainty and outcome strength in revised forecasts

Abstract

What do lay people think about revised forecasts of future outcomes? A series of experiments show that when climate change forecasts are revised in an upward direction (e.g., a higher sea level rise is predicted in light of new information), the forecast is perceived as more certain in contrast to revisions in a downward direction. This association is bidirectional so that people also think a forecast that has become more certain (uncertain) indicates a stronger (weaker) outcome. Furthermore, when the timing of the outcome is revised, a predicted sooner occurrence (a “stronger” outcome) was judged to be more certain than a predicted delayed occurrence. Upward revisions may also lead to more positive impressions of the forecast and the forecaster, with clear implications for the communication of uncertainty, both for climate change and in other domains. Different theoretical explanations for the results are discussed.