Analyzing heterogeneity in the effects of behavioral climate interventions on individual beliefs across sociodemographics, attitudes, and norms

Addressing climate change requires global shifts in individual beliefs at scale. While several behavioral interventions have been developed to strengthen climate change beliefs (e.g., by framing climate change as a psychologically proximal risk), the effectiveness of such interventions differs across individuals. Yet, the extent and drivers of such heterogeneity in intervention effectiveness remain largely unclear. Here, we aim to understand individual-level differences in the effectiveness of 11 expert-crowdsourced interventions on climate change beliefs across two randomized controlled trials (RCTs) (RCT 1: N = 59,508 individuals from 63 countries; RCT 2: N = 1,610). First, our analysis reveals large heterogeneity in the effectiveness: even the most effective intervention in terms of average treatment effect fails to motivate belief change for 20% of individuals, while interventions regarded as “ineffective” still positively influence 47%. Second, we identify key drivers across sociodemographics, attitudes, and norms, thereby showing that interventions effective in the Global North often backfire in the Global South, where different socioeconomic contexts shape responses. Third, we performed an online field study (N = 772,777) to externally validate the findings, showing that personalizing interventions increases effectiveness by more than 30%. Our findings emphasize the importance of personalization in behavioral climate interventions to maximize the effectiveness of behavioral strategies and foster widespread support of climate action.