Climate change is an urgent global issue, with demands for personal, collective, and governmental action. Although a large body of research has investigated the influence of communication on public engagement with climate change, few studies have investigated the role of interpersonal discussion. Here we use panel data with 2 time points to investigate the role of climate conversations in shaping beliefs and feelings about global warming. We find evidence of reciprocal causality. That is, discussing global warming with friends and family leads people to learn influential facts, such as the scientific consensus that human-caused global warming is happening. In turn, stronger perceptions of scientific agreement increase beliefs that climate change is happening and human-caused, as well as worry about climate change. When assessing the reverse causal direction, we find that knowing the scientific consensus further leads to increases in global warming discussion. These findings suggest that climate conversations with friends and family enter people into a proclimate social feedback loop.

Behavioral change is essential to mitigate climate change. To advance current knowledge, we synthesize research on interventions aiming to promote climate change mitigation behaviors in field settings. In a preregistered second-order meta-analysis, we assess the overall effect of 10 meta-analyses, incorporating a total of 430 primary studies. In addition, we assess subgroup analyses for six types of interventions, five behaviors, and three publication bias adjustments. Results showed that climate change mitigation interventions were generally effective ( d _unadjusted = 0.31, 95% CI [0.30, 0.32]). A follow-up analysis using only unique primary studies, adjusted for publication bias, provides a more conservative overall estimate ( d = 0.18, 95% CI [0.13, 0.24]). This translates into a mean treatment effect of 7 percentage points. Furthermore, in a subsample of adequately powered large-scale interventions ( n > 9,000, k = 32), the effect was adjusted downward to approximately 2 percentage points. This discrepancy might be because large-scale interventions often target nonvoluntary participants by less direct techniques (e.g., “home energy reports”) while small-scale interventions often target voluntary participants by more direct techniques (e.g., face-to-face interactions). Subgroup analyses showed that interventions based on social comparisons or financial incentives were the most effective, while education or feedback was the least effective. These results provide a comprehensive state-of-the-art summary of climate change mitigation interventions, guiding both future research and practice.

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.

Pro-environmental behaviors (PEBs) are crucial to reducing environmental degradations, and much research has focused on two key psychological antecedents: pro-environmental attitudes and efficacy beliefs. Yet, the evidence of their direct and interactive relationships are mixed. Further, few studies investigate how these key relationships vary across different countries and contexts. Using data from a large international survey ( N = 11,000) in 11 countries, we examine relationships among environmental attitudes, efficacy, and PEBs. Overall environmental attitudes are a strong predictor of PEBs, while efficacy has a small direct and a non-significant moderation effect. Within countries, both direct and moderation relationships involving efficacy are tiny. The relative dominance of environmental attitudes as a predictor raises questions about the unique importance of efficacy in explaining PEBs separate from attitudes (and covariates). The nuanced connections between these variables within individual countries highlight the importance of more diverse global environmental research.

Reducing global warming will require enacting strong climate policies, which is unlikely to happen without public support. While prior research has identified varied predictors of climate change policy support, it is unclear which predictors are strongest for the American electorate as a whole, and which predictors are strongest for Democrats and Republicans. In a nationally representative sample of registered voters (n = 2063), we use relative weight analysis to identify the strongest predictors of public climate policy support. We find that, among registered voters in the USA, the five most important predictors of climate policy support are: worry about global warming; risk perceptions; certainty that global warming is happening; belief that global warming is human-caused; and general affect toward global warming. Collectively, these five variables account for 51% of the variance in policy support. Results split by political party indicate that pro-climate injunctive norms and global warming risk perceptions are the variables that differ most between Republicans and Democrats, accounting for significantly more variance in policy support among Republicans. These findings can inform policymakers and advocates seeking to build public support for climate action.

It is well established that conservatives in the United States are substantially less likely than liberals to accept that climate change is happening and is human caused and are less supportive of policies to limit climate change. However, it is likely that ideological differences in climate change beliefs, attitudes, and policy preferences are smaller when people have close friends and family members who care about climate change. Here, we use nine nationally representative survey samples (total N = 16,168) to evaluate this claim and test if perceived social consensus predicts a smaller difference in climate change beliefs between liberals and conservatives. We find that social consensus plays an important role in climate change beliefs, attitudes, and policy preferences for people across the ideological spectrum, but especially among conservatives. These findings provide important insights on how to bridge ideological divides in large social dilemmas such as climate change.