There's a near-universal scientific consensus (97–99.9%) that human activity is causing climate change. However, public understanding often significantly underestimates this consensus. This misperception negatively impacts efforts to mitigate climate change, as individuals who underestimate the consensus are less likely to believe in climate change, worry about it, or support public action. Communicating the scientific consensus (e.g., that 97% of climate scientists agree on human-caused climate change) has been shown to effectively correct misperceptions and influence climate change attitudes in previous studies, primarily from Western, high-income countries. This study addresses the significant gap in knowledge regarding the effectiveness of such messaging in a diverse, global sample by testing two consensus messages across 27 countries. The first is a classic message focusing on the reality of human-caused climate change. The second is an updated message that also emphasizes the scientific agreement that climate change is a crisis. The study hypothesizes that both messages will be effective, potentially more so for those with lower message familiarity and higher misperceptions, and explores potential moderation effects based on individual-level (message familiarity, trust in climate scientists, political ideology) and country-level (individualism-collectivism, power distance) characteristics.

A substantial body of experimental research supports the efficacy of communicating the scientific consensus on climate change in shifting perceptions, beliefs, worry, and support for action. Meta-analyses show that such messaging significantly reduces consensus misperceptions and, to a lesser extent, increases pro-climate attitudes. However, most prior studies are limited to Western, high-income countries, notably the United States. The lack of research outside these regions hinders a comprehensive understanding of the generalizability of this communication strategy, especially given the global nature of climate change and the need for international cooperation.

This preregistered study used a between-participants online experiment with three conditions: a control group, a classic consensus message group, and an updated consensus message group. Participants (N = 10,527) from 27 countries across six continents were recruited using convenience sampling methods (snowballing, mailing lists, social media, and Prolific—in Canada and Mexico). Participants first estimated the scientific consensus on climate change and whether it is a crisis. They were then randomly assigned to one of the three conditions and exposed to the corresponding message. Following a distractor task, they reassessed their consensus perceptions, confidence, and provided data on personal climate change beliefs, worry, support for public action, and potential moderators (message familiarity, trust in climate scientists, political ideology). Bayesian model-averaging approaches, using mixed-effects linear and ordinal regressions, were employed to analyze the data, controlling for pre-intervention perceptions and demographic characteristics.

The study found substantial misperceptions of the reality consensus across all 27 countries, demonstrating a potential for improvement through consensus messaging. The classic message significantly increased perceptions of the scientific consensus (Cohen's d = 0.47, 95% CI [0.41, 0.52]) and slightly increased beliefs in the reality and human causation of climate change, as well as worry. However, it had little to no effect on support for public action. The updated message produced similar results, with no added benefit over the classic message. Both messages were significantly more effective for individuals with lower message familiarity and higher initial misperceptions, including those with lower trust in climate scientists and right-leaning ideologies. Exploratory analyses showed no significant moderation by country-level cultural dimensions (individualism-collectivism and power distance).

The findings demonstrate that communicating the scientific consensus on climate change is effective across diverse cultural and political contexts. The similar effectiveness of the classic and updated messages suggests that simply emphasizing the overwhelming scientific agreement on the reality of human-caused climate change is sufficient. The lack of a direct effect on support for public action highlights that consensus messaging may need to be complemented by other strategies to effectively motivate policy support. The identified moderators (message familiarity, pre-existing beliefs, trust in science, and political leaning) provide valuable insights for targeting interventions to specific subgroups. The absence of significant country-level moderation suggests that the effectiveness of consensus messaging transcends cultural differences, at least within the scope of this study.

This large-scale, multi-country study confirms the effectiveness of scientific consensus messaging in correcting misperceptions and modestly shifting attitudes towards climate change. The message's effectiveness is amplified among those least familiar with the consensus and possessing inaccurate pre-existing beliefs. Future research should explore complementary strategies to enhance the impact on support for policy action and investigate how to communicate the scientific urgency of the climate crisis more effectively. Further research with larger, representative samples is needed to test for potential country-level moderation effects more robustly.

The convenience sampling approach may limit the generalizability of the findings, particularly concerning the underrepresentation of hard-to-reach populations. The use of single-item measures for some constructs, like support for public action, could be a limitation, as could the lack of statistical power to robustly test for country-level moderation effects. Further limitations include the lack of measurement for pre-intervention beliefs across all measured outcomes, and a focus on direct effects rather than the indirect effects emphasized in the Gateway Belief Model.