How Effective is Nudging in the Long Run? A Meta-Analysis of Pro-Environmental Behavior

Nudging has become a widely used policy instrument for promoting pro-environmental behavior. Although extensive evidence demonstrates that nudges are effective in the short term, far less is known about whether these effects persist over time. This study presents the first systematic literature review and meta-analysis focused explicitly on the long-term effects of environmental nudges. A total of 42 publications reporting 140 effect sizes (N = 613,894) were synthesized using a three-level random-effects model. Across all studies, nudging interventions produced a small overall effect (d = 0.30, 95% CI [0.19, 0.41]). An analysis of the temporal dynamics based on 61 effect sizes showed that long-term effects remained positive and statistically significant, although smaller in magnitude than short-term effects. A continuous meta-regression revealed a significant decline in effectiveness over time (β = –0.0113), indicating gradual behavioral decay. Quartile analyses confirmed this pattern, with significant effects up to 60 days after intervention and increasing heterogeneity in effectiveness thereafter. Moderator analyses revealed substantial variation across nudge types. The findings provide systematic evidence that environmental nudges do lead to persistent behavior change, though with clear attenuation over time. These results offer important implications for policymakers and organizations designing long-term behavioral interventions and highlight the need for future research on mechanisms that enhance temporal stability.