Biodiversity loss or climate change? Which identity activation fosters collective urban gardening among youth

The urgency of climate change and biodiversity loss increasingly calls for behavioral approaches that can explain and influence how individuals engage in pro-environmental practices. In particular, biodiversity loss, often less visible, remains difficult to communicate in ways that mobilize broad societal support. One promising pathway lies in activating social identities that align with sustainability goals. This research addresses a critical gap in behavioral sustainability scholarship by clarifying how different identity framings, social and environmental (biodiversity conservation versus climate change), shape young people’s willingness to engage in collective urban gardening to foster nature-based urban initiatives. Building on experimental evidence that social framing can be particularly effective in increasing engagement, the research replicates and extends prior designs in a French context to test whether distinct environmental framings differ in their effects, specifically contrasting messages that emphasize tackling climate change with those highlighting biodiversity conservation.

In collaboration with “Pyramide“, a university urban garden in Paris, a framed field experiment was conducted involving 30 000 university students.  Participants were randomly assigned to receive one of four message framings about urban gardening opportunities: environmental (climate change), environmental (biodiversity conservation), peer-group social (emphasizing opportunities to connect with new friends), or a neutral control (basic gardening information). Responses are measured through digital engagement with a project landing page, complemented by self-reported attitudes and behavioral intentions. The study leverages online invitations and digital tracking tools aligned with the lifestyle and media habits of Generation Z in urban settings.

The study is expected to generate robust, scalable evidence on how identity-based messaging shapes both behavioral engagement and pro-environmental attitudes. It aims to offer actionable insights for designing communication strategies to involve youth in biodiversity-supporting urban initiatives. The study tests four hypotheses:  social identity framing increases willingness to participate in urban gardening relative to a neutral control;  environmental framings (biodiversity loss or climate change) strengthen pro-environmental attitudes relative to a neutral control;  climate change framing is more persuasive than biodiversity loss framing in motivating behavioral intentions, given its higher salience among youth; and social identity framing primarily boosts behavioral engagement, whereas environmental framings primarily enhance attitudinal alignment with biodiversity and climate goals