A climate action intervention increases four psychological motivators, as well as climate advocacy, activism and civic participation.

Urgent climate action is needed to keep warming below 2°C and protect hundreds of millions from climate collapse. As part of a broader Registered Report series, this study examined whether a longitudinal intervention designed to strengthen psychological correlates of pro-environmental behaviour could motivate n = 31 university students in The Netherlands to take climate action. The intervention was delivered over six weeks through interactive lessons and activities informed by psychological theories and interventions. The goal was to increase pro-climate behaviours by targeting 12 psychological factors. Participants completed surveys assessing these correlates, as well as ecological momentary assessments of individual and collective pro-climate behaviours before and after the intervention, and after three months (14 days each). A control group was included (n = 27). Results showed that 4 of the 12 psychological correlates increased significantly: emotional engagement, collective efficacy, the bottom-up theory of change (the belief that change can start from grassroots action and spread systemically) and climate appraisal. Three (except appraisal) remained elevated at the three-month follow-up. Civic engagement, advocacy and activism increased after the intervention in the experimental group relative to control group. The increase in activist behaviour was predicted by the development of a bottom-up theory of change.