What the evidence shows

This paper asks a deceptively simple question: does short-term volunteer activism produce measurable, lasting benefits? The authors use the original Earth Day (April 22, 1970) — in which an estimated 20–25 million Americans, roughly one in ten, participated in teach-ins, cleanups, and demonstrations — as a natural experiment.

Because places with strong pre-existing environmental attitudes might simply have had more successful Earth Day events (reverse causation), the authors instead exploit random variation in local weather on that single day. Their logic: rain or shine on April 22, 1970 should be unrelated to a community's underlying environmental values, so if outcomes differ later between rainy and sunny counties, that difference can be attributed to the disrupted or enhanced activism itself.

They then trace three downstream outcomes over the following one to two decades: self-reported environmental policy attitudes (via the GSS), local air pollution (carbon monoxide levels), and infant health (congenital abnormality rates), always comparing counties by their weather on that one day in 1970.

Key Findings

• Consumers readily classified 261 self-photographed items as "green" or "not green" without needing information on carbon impact — meaning green/not-green judgments are intuitive and social, not calculative.

• Recycling was the most salient and universally adopted behaviour among participants (79 of 261 photographs, 30%), consistent with the paper's account of recycling as an activity that has become both "green" and "normal."

• Ideas of "normal" are not static: participants repeatedly described how practices (e.g., packaging use, clothes-washing frequency, plastic bag use) have shifted generationally, supporting the paper's claim that normalisation is a time-dependent social process, not a fixed consumer trait.

Stand-out data points

• 30%: share of all participant-submitted "green" photographs depicting recycling — the single most normalized green behaviour identified.

• Qualitative — "You don't even think about it… it's just, it's just normal": a participant's description of driving a car, illustrating how "normal" status can suppress critical evaluation of a behaviour's environmental impact even when the person acknowledges it isn't green.

Examples of how Understories uses this research

• Actionability offers a rare, credible answer to "does showing up actually matter?" — useful for countering advocate burnout or cynicism about individual action.

• Solution focus Reinforces the case that participation-based (not just policy-based) climate action produces real outcomes — useful evidence for solution-oriented messaging.

• Hope doom balance Strongly hope-supporting: directly rebuts the "my action doesn't matter" narrative with two decades of measurable downstream benefit.

• Beneficence Strongly supports advocate integrity — this is exactly the kind of research that helps communicators make an honest, evidence-backed case for participation rather than an exaggerated one.

• Accountability Long shelf life for the core claim (activism has lasting effects), but the specific context (1970s US, pre-digital organizing) should be flagged as dated when applied to modern digital-first campaigns.

— non-exhaustive

Key quote

On why this matters for measuring activism generally: "there can be benefits to volunteer activity that would be impossible to identify until years after volunteering occurs."

© American Economic Association, 2023 — All rights reserved.

Last update: 3 September 2026

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