What the evidence shows

This is one of the largest empirical tests ever conducted comparing different behavioral-science strategies for shifting climate beliefs and behaviors. The researchers crowdsourced 11 distinct intervention approaches from behavioral science experts — including reducing psychological distance, invoking scientific consensus, dynamic social norms, moral reframing, future self-continuity, negative emotion ("doom and gloom") messaging, and writing a letter to a future generation — and tested each head-to-head against a no-intervention control, in the same experiment, across a genuinely global sample.

Critically, the study measured four distinct outcomes rather than just one: self-reported belief in climate change, support for climate policy, willingness to share climate information on social media, and — most novel — a real behavioral measure, where participants could earn actual donations toward tree planting by completing an effortful cognitive task. This let the authors directly compare which interventions work for which outcome, rather than assuming an intervention that shifts beliefs will also shift costly behavior.

The study explicitly addresses the "WEIRD" (Western, Educated, Industrialized, Rich, Democratic) sampling problem that limits most behavioral science research, deliberately recruiting across 63 countries with international collaborators, though the authors are candid that convenience sampling still shaped who was reached in many countries.

Key Findings

• Intervention effectiveness varied substantially by people's pre-existing climate beliefs: several interventions worked best on people who were "uncertain" rather than confirmed skeptics or firm believers, and one intervention (negative emotion) appeared to backfire on policy support specifically among people with low initial belief.

• Climate beliefs were most increased by reducing psychological distance (making climate change feel geographically/temporally close) — a 2.3 percentage-point increase in belief compared to control.

• Policy support was most increased by having people write a letter to a future-generation member — a 2.6 percentage-point increase.

Stand out data points

• 85.7% global baseline belief in climate change, with 63-country coverage. Belief in climate change was already high and remarkably consistent across nearly all 63 countries surveyed, while willingness to share climate information on social media varied dramatically by country — from 17.6% in Latvia to 93.3% in Kenya — suggesting local norms around public climate discussion vary far more than underlying belief.

• 12.1 percentage points: negative-emotion messaging's boost to information-sharing intent — by far the single largest effect size in the entire study, but paired with evidence that this same negative-emotion approach reduced effortful tree-planting behavior and backfired on policy support among skeptics.

• 0 out of 11 interventions increased the effortful tree-planting task; several decreased it. Despite testing 11 well-supported theoretical approaches, none succeeded at increasing genuinely costly pro-environmental action, and the interventions that worked best on beliefs or sharing were often among those that reduced tree planting.

Examples of how Understories uses this research

• Personal relevance Interventions grounded in personal or intergenerational stakes (future self-continuity, letter to future generation) were among the more broadly effective across outcomes and across the belief spectrum, including with skeptics.

• Solution focus Interventions grounded in efficacy and agency (e.g., "effective collective action," "letter to future generation") performed comparatively well on policy support, suggesting solution-focused, agency-affirming framing may be a safer bet than fear appeals for high-effort or policy-relevant outcomes.

• Hope doom balance This study is a rare large-scale, real-world test of the doom-vs-hope debate, finding empirical support for both sides depending on outcome — doom messaging helped low-effort sharing but hurt costly action and policy support among skeptics, undercutting any blanket recommendation either way.

• Autonomy The study's country-and-subgroup-level web tool (built by the authors and cited in the paper) exemplifies the kind of transparent, explorable evidence base to cite from — allowing traceable, specific claims (e.g., "which intervention worked best for this audience and this outcome") rather than blanket assertions.

• Justice It is one of the only megastudies of its kind to prioritize non-WEIRD sampling across 63 countries, and the authors are transparent about where their sampling still falls short (convenience sampling, uneven demographic matching).

  — non-exhaustive.

Key quote

“We all perceive climate change to be such a huge problem that it is almost impossible to overcome. Restoring people’s sense of collective efficacy, the idea that we can have an impact on this massive problem, could help motivate people to join forces and work together.” Kimberly Doell in Development and Cooperation.

© 2024 The Authors, some rights reserved. Distributed under a Creative Commons Attribution License 4.0 (CC BY).

Last update: 3 September 2026

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