Positive, global, and health or environment framing bolsters public support for climate policies

The Paris Agreement aims to limit global temperature rise to well below 2°C, requiring increasingly ambitious national commitments. While governments set policy, public support is crucial for effective climate action and can influence mitigation targets. Communication strategies, particularly message framing (emphasizing certain aspects of an issue), are thought to shape engagement and support. Prior studies have examined: (a) valence (positive opportunity vs negative threat), (b) thematic focus (e.g., health, environment, economy), and (c) spatial and temporal scales (local vs global; present vs future). However, few studies assess these frames simultaneously or across diverse national contexts. This study asks which combinations of frames most effectively increase public support for climate policies, and whether effects vary across countries and societal subgroups. It focuses on five high-emitting countries—China, Germany, India, the UK, and the USA—to capture variation in development, political systems, culture, climate exposure, and policies, using representative quota sampling and a conjoint experimental design.

The paper situates its work in literature on climate communication and framing, which shows that message construction can shape public engagement. Studies have contrasted positive opportunity frames with negative threat frames; explored thematic framings such as health and economic impacts to increase personal relevance; and tested spatial (local vs global) and temporal (current vs future) framings. Evidence is mixed and often country-specific, with much prior research centered in high-income Western contexts. Notably, existing work typically investigates individual frames in isolation, leaving a gap on the simultaneous, causal effects of multiple frames and their generalizability across countries and audience subgroups (e.g., ideological differences, age, gender). This study addresses these gaps by testing multiple frames together in a cross-national conjoint experiment.

Design: Randomized paired-profiles conjoint survey experiment embedded in nationally (or urban) representative online panels in five countries (China, Germany, India, UK, USA), fielded by Deltapoll in October 2020 under ethical approval (University of Birmingham, project 766927). Quotas on age, gender, and region; for China and India, samples representative of urban populations due to online panel recruitment. Sample: Total n = 7,512 (China 1,502; Germany 1,501; India 1,506; UK 1,500; USA 1,503). Each respondent evaluated 5 pairs of messages (10 messages), yielding 75,120 message evaluations. Conjoint attributes (frames) and levels: - Valence: Positive (opportunity) vs Negative (threat) - Theme: Economic, Environmental, Health, Migration - Scale: Personal (individual), Community, Country (national, country name localized), World (global) - Time: Now (present), 2030 (near-term), 2050 (long-term) Messages: 96 unique profiles created via random assignment across attributes. Each statement followed a consistent structure: opening valence clause, theme with a concrete example, then a sentence referencing valence outcome, scale, and time. Two randomly generated statements were shown side-by-side per task; respondents chose which would make them more likely to support policies to tackle climate change. Respondents completed five such choice tasks. Measures: Primary outcome is forced-choice indicating which message increases likelihood of support for climate policies. A secondary rating (willingness to pay per month) was collected for robustness but not reported as main outcome. Analysis: Estimand is marginal means—the mean probability of choosing a profile level, averaging over other attributes. Estimates computed using the cregg package in R, incorporating sampling weights. Robustness checks included earlier pilots in all five countries, and re-analysis excluding respondents unwilling to pay any amount to support climate policy; results were substantively similar.

Cross-country main effects (Fig. 1): - Valence: Positive (opportunity) framing increases support in China, UK, USA; negative (threat) lowers support. In India, valence effects are not statistically significant. In Germany, the threat frame increases support while opportunity lowers it. - Theme: Environmental framing increases support in all five countries. Health framing increases support in China, India, UK, USA (not statistically significant in Germany). Economic framing shows no significant effect in any country. Migration framing decreases support in all five countries. - Scale: Global (world) framing increases support in China, Germany, India, UK (not significant in USA). Personal (individual) framing decreases support in Germany, India, UK (not significant in China, USA). - Time: Present (now) and near-term (2030) increase support relative to 2050 in Germany, India, UK, USA; time frame has no significant effect in China. The 2050 frame tends to reduce support in the four countries where effects are significant. Subgroup analyses (Fig. 2 and Fig. 3): - Socio-demographics (pooled across countries): The opportunity > threat advantage is statistically significant for males, age 30+, university-educated, lower-than-average income, and employed/retired; it is not statistically significant for females, under-30s, non-graduates, higher-than-average income, unemployed/students. For theme, scale, and time, effects are broadly consistent across socio-demographic subgroups. - Concern about climate change: Among respondents not concerned about climate change, opportunity framing increases support and threat framing reduces it, with larger effect sizes than among concerned respondents. Health framing increases support, and migration framing decreases support, among the unconcerned. Country-specific nuance: In the USA, among the unconcerned, environmental framing reduces support, while economic and health frames increase support; scale effects among the concerned in the USA are not significant. Robustness: Pilot studies and analyses excluding respondents unwilling to pay any amount yielded similar patterns, supporting robustness of main results.

The study demonstrates that specific framings can causally increase stated support for climate policies across diverse national contexts. Positive (opportunity) framing is effective in China, the UK, and the USA and is particularly impactful among individuals unconcerned about climate change, suggesting such messages may circumvent ideological barriers by emphasizing shared benefits. Germany is an exception where threat framing performs better, potentially reflecting a public discourse long focused on climate risks. Thematically, environmental and health frames reliably bolster support (with health effective in four countries), whereas migration framing consistently backfires, reinforcing caution against simplistic climate–migration linkages amid politicized migration debates. Economic framing shows no aggregate effect, possibly due to simultaneous activation of perceived costs and benefits that offset each other. For scale and time, global and immediate/near-term frames generally elicit higher support than individual and distant-future (2050) frames, perhaps because respondents recognize global impacts more readily than personal ones and perceive immediacy as more compelling; time effects are absent in China. Overall, apart from valence in some subgroups, effects are broadly consistent across socio-demographics, indicating wide applicability of the effective frames.

This multi-country conjoint experiment provides causal evidence that message framing can increase public support for climate policies. Across five high-emitting countries, environmental and health themes, global scale, and immediate/near-term time horizons tend to bolster support, while migration themes reduce it and economic framing has no net effect. Positive (opportunity) framing is broadly beneficial—especially among individuals unconcerned about climate change—though country context matters (e.g., Germany). These findings inform communicators and policymakers seeking to build support for stronger climate action. Future research should test interactions among frames, assess real-world behavioral outcomes beyond perceived support, and examine the durability and generalizability of health framing post-COVID-19 and across additional country contexts.

- External validity: The forced side-by-side message comparison differs from typical real-world exposure; respondents were required to choose one of two messages and could not express outright opposition to climate policies. - Outcome measure: The primary outcome captures perceived likelihood of support rather than observed behavior or actual policy support. - Context effects: Fieldwork occurred during the COVID-19 pandemic, potentially increasing salience and effectiveness of health framing. - Sampling constraints: China and India samples are representative of urban populations due to online panel recruitment, which may limit national generalizability. - While robustness checks (e.g., excluding respondents unwilling to pay) yielded similar results, they do not fully address the above limitations.