A Registered Report Megastudy on the Persuasiveness of the Most-Cited Climate Messages

• In Event: Media and Misinformation

Abstract

Background
Effective climate change communication is critical to building public support for climate policy. Yet decades of messaging research have produced findings that are difficult to compare and may no longer hold in today's polarized information environment. Prior studies test individual strategies using inconsistent measures and samples, making it impossible to rigorously compare their effectiveness. At the same time, replication failures raise questions about whether widely-cited messaging approaches remain viable.
Research Question
Which climate change messaging strategies most effectively shift Americans' pro-environmental attitudes and behavioral intentions, and do these effects vary by partisan affiliation?
Data
This study draws on an original, large-scale survey experiment conducted between April and June 2024 with a national, non-probability sample of 13,544 American adults, recruited through Bovitz-Forthright and matched to U.S. population benchmarks on gender, age, race and ethnicity, education, region, and partisan identity.
Design and Methods
Using a preregistered megastudy design, participants were randomly assigned to one of ten treatment conditions or a control condition. The ten messaging strategies were selected from 157 climate messaging papers based on citation counts and evidence of statistically significant effects on at least one outcome of interest. Outcomes included belief in climate change, climate change concern, support for general and specific mitigation policies, political pro-environmental behavioral intentions, and donations to pro-environmental organizations. OLS regression models controlled for pre-treatment outcome levels.
Findings
Several messaging strategies produced statistically significant improvements across multiple outcomes, with effect sizes ranging from one to four percentage points. A message highlighting the scientific consensus around climate change most strongly increased climate change belief, while messages highlighting that supporting climate change is consistent with values such as sanctity and system preservation Framing had the largest effects on climate change concern and pro-environmental behavioral intentions, respectively. Notably, treatment effects were remarkably consistent across party lines, contrary to theories predicting that targeted messages would differentially persuade Republicans versus Democrats. No messaging strategy significantly increased pro-environmental donation.
Implications
These findings carry important implications for climate communicators and policymakers. Several well-cited messaging strategies do reliably shift pro-environmental attitudes, but effects are modest and unlikely to produce lasting change without repeated or higher-dose exposure. The lack of partisan heterogeneity suggests that communicators may not need to develop separate messaging for Republican and Democratic audiences. Furthermore, the disconnect between attitude change and actual behavior — particularly donations — underscores the limits of short-form messaging as a policy tool and points to the need for intervention strategies that target behavior more directly.

Author

• Jan Gerrit Voelkel, Cornell University
  Presenting Author