Uncertainty is inherent to science and science communication. However, the evidence appears mixed regarding whether portraying uncertainty in science communication has positive or negative effects. We review a diverse range of experimental literature (k = 48; from 40 searches and 8000 retrievals), summarize the extant findings, and observe how the effects vary across four different types of communicated uncertainty (deficient, technical, scientific, and consensus uncertainty). The results indicate that most findings of negative effects (such as reduced credibility and beliefs) are from experiments that operationalized uncertainty as disagreement or conflict in science (consensus uncertainty). In this review, consensus uncertainty was never found to have positive effects. In contrast, uncertainty in the form of quantified error ranges and probabilities (technical uncertainty) in these studies has had only positive or null effects, not negative effects. We also highlight frequent moderators of the effects of uncertainty, such as prior beliefs and worldviews.

Despite Greta Thunberg's popularity, research has yet to investigate her impact on the public's willingness to take collective action on climate change. Using cross‐sectional data from a nationally representative survey of U.S. adults (N = 1,303), we investigate the “Greta Thunberg Effect,” or whether exposure to Greta Thunberg predicts collective efficacy and intentions to engage in collective action. We find that those who are more familiar with Greta Thunberg have higher intentions of taking collective actions to reduce global warming and that stronger collective efficacy beliefs mediate this relationship. This association between familiarity with Greta Thunberg, collective efficacy beliefs, and collective action intentions is present even after accounting for respondents’ overall support for climate activism. Moderated mediation models testing age and political ideology as moderators of the “Greta Thunberg Effect” indicate that although the indirect effect of familiarity with Greta Thunberg via collective efficacy is present across all age‐groups, and across the political spectrum, it may be stronger among those who identify as more liberal (than conservative). Our findings suggest that young public figures like Greta Thunberg may motivate collective action across the U.S. public, but their effect may be stronger among those with a shared political ideology. Implications for future research and for broadening climate activists’ appeals across the political spectrum are discussed.

While uncertainty is central to science, many fear negative effects of communicating scientific uncertainties to the public, though research results about such effects are inconsistent. Therefore, we test the effects of four distinct uncertainty frame types (deficient, technical, scientific, consensus) on three outcomes (belief, credibility, behavioral intentions) across three science issues (climate change, GMO food labeling, machinery hazards) with an experiment using a national sample ( N = 2,247) approximating U.S. census levels of age, education, and gender. We find portraying scientific findings using uncertainty frames usually does not have significant effects, with an occasional exception being small negative effects of consensus uncertainty.

This report is based on findings from a nationally representative survey – Climate Change in the American Mind – conducted by the Yale Program on Climate Change Communication (climatecommunication.yale.edu) and the George Mason University Center for Climate Change Communication (climatechangecommunication.org). Interview dates: March 29-April 8, 2019. Interviews: 1,291 adults in the U.S. (18+).

Sharing personal stories of how climate change is already harming people is a promising communication strategy to engage diverse and even skeptical audiences. Using two experiments, we test the effects of a radio story on the climate change beliefs and risk perceptions of political moderates and conservatives. The radio story, which aired on hundreds of stations across the U.S., is a North Carolina sportsman’s personal account of how climate change has already affected the places he loves. Both experiments found positive effects on global warming beliefs and risk perceptions. Additionally, Study 2 found these effects were mediated by emotional reactions of worry and compassion. These studies suggest personal stories can be a persuasive communication strategy.