The 2015 Paris Agreement aims to limit global temperature increase, but its success hinges on national commitments and public support. While governments set policies, public engagement is vital, especially for non-binding agreements like Paris. The study investigates how different framings of climate change messages influence public support for mitigation policies. Communication science defines framing as highlighting specific issue aspects. Previous research explored the impact of positive (opportunity-focused) versus negative (threat-focused) framings, thematic focuses (health, economic, etc.), and spatial and temporal scales (local/global, present/future). However, no study comprehensively assessed these frames simultaneously. This research employs a conjoint survey experiment to address this gap, analyzing the causal effects of various frames on support for climate policies across five high-emitting countries: the USA, China, India, Germany, and the UK. These countries were chosen to capture diverse socioeconomic development levels, political systems, cultures, climate change exposures, and policy approaches. The experiment uses quota sampling for age, gender, and region to ensure representative samples (at least 1500 participants per country), enabling analysis of how framing effects vary across countries and subgroups within countries, especially those unconcerned about climate change. This focus is critical due to the significant portion of the population that does not perceive climate change as an urgent threat.

Existing literature on climate change communication highlights the importance of framing in shaping public attitudes and support for policy. Studies have examined the effectiveness of positive versus negative framing, exploring whether emphasizing opportunities or threats yields greater support. Research also investigated the impact of focusing on specific themes like health and economic consequences to make climate change more relatable. The role of spatial and temporal scales has been examined, determining whether local or global impacts, present or future consequences, are more effective in driving support for policies. However, a comprehensive analysis integrating these different framing aspects simultaneously was lacking before this study. The current research builds upon this foundation by explicitly evaluating these framing effects concurrently within a multi-country context, allowing for nuanced cross-cultural comparisons.

A conjoint survey experiment was conducted in October 2020 using online panels in five countries (USA, China, India, UK, Germany). The experiment employed a randomized paired profiles design, presenting participants with pairs of hypothetical statements about climate change. Each statement varied across four attributes: valence (positive or negative framing), theme (economic, environmental, health, or migration), scale (individual, community, national, or global), and time (present, 2030, or 2050). The 96 unique message profiles were tested in pre-study pilots. Participants (at least 1500 per country, totaling 7512) selected the statement making them more likely to support climate policies. Quota sampling ensured representative samples (based on age, gender, and region, or urban populations in China and India). Data was weighted to ensure national representativeness. The analysis used the 'cregg' package in R to estimate marginal means, accounting for sampling weights. Robustness checks were performed, including analysis excluding those unwilling to pay anything towards climate policies, and comparison with quantitative ratings of support. The study received ethical approval from the University of Birmingham. Surveys were translated professionally and verified by native speakers with subject matter expertise in China and Germany.

The analysis revealed significant variations in the effectiveness of different frames across countries and subgroups. In China, the UK, and the USA, positive framing significantly increased support for climate policies, while negative framing decreased support. In India, valence had no significant effect, and in Germany, negative framing was more effective. Across all five countries, environmental framing consistently increased support, while migration framing consistently decreased it. Health framing significantly boosted support in four countries. The economic frame showed no significant effect. Framing climate change at the global level and focusing on immediate impacts (present day or 2030) increased support across most countries, while individual-level or distant (2050) framings generally decreased support. Subgroup analysis revealed that the effect of positive versus negative framing varied significantly depending on individuals' level of concern about climate change. While positive framing generally increased support, this effect was more pronounced among those unconcerned about climate change. The health framing also positively impacted support in this unconcerned group. Figures 1, 2 and 3 in the paper provide detailed graphical representations of these findings. Further analysis showed that the effectiveness of certain combinations of frames varied by country, suggesting the importance of tailoring messaging to specific contexts.

This study offers valuable insights into crafting effective climate change communication. The findings highlight the importance of context-specific messaging. The effectiveness of positive framing over negative framing varied across countries, possibly due to existing public discourse and political contexts. The consistent positive impact of environmental and health framing demonstrates the power of aligning climate action with shared societal values. The negative effect of migration framing underscores the need for cautious messaging on this complex and sensitive issue. The results emphasize the potential for targeted communication to reach those unconcerned about climate change, leveraging positive and health-focused messages. The study's experimental design allows for a causal inference on framing effects, strengthening its findings. However, limitations exist related to external validity; the side-by-side comparison of messages doesn't replicate real-world information consumption, and the forced choice design prevents expression of opposition to climate policies. While robustness checks were performed, these limitations should be considered.

This multi-country conjoint experiment demonstrates the significant impact of message framing on public support for climate policies. Positive framing, especially when combined with health and environmental themes, and global and immediate time frames, significantly increased support across various countries. Crucially, these framings proved especially effective in mobilizing support among individuals unconcerned about climate change. The findings provide valuable guidance for policymakers and communicators on crafting effective messaging to build wider public support for ambitious climate action. Further research should explore interactions between different frames and assess the long-term impact of various communication strategies. Investigating the effectiveness of tailored messaging in different cultural contexts would also enhance our understanding of how to effectively communicate the urgency and benefits of climate action.

The study’s conjoint experiment design, while providing strong causal inferences, has limitations in external validity. Presenting messages side-by-side may not fully reflect real-world information processing. The forced-choice format prevented respondents from expressing opposition to climate policies. Although efforts were made to address these limitations through robustness checks, these limitations should be considered when interpreting the results. Additionally, data collection coincided with the COVID-19 pandemic, potentially influencing the salience of health framing, warranting further investigation in future studies. Future research could explore potential interaction effects between framing variables, providing a more nuanced understanding of their combined impact.