What works best in promoting climate citizenship? A randomised, systematic evaluation of nudge, think, boost and nudge+

Nudges have been increasingly deployed to deliver climate policies in the last decade. Recent evidence shows nudges are hard to scale–up. So can we use nudges more effectively, or should we rely on other tools of behaviour change? We argue that reflective strategies can enhance nudges by encouraging agency and ownership in citizens. We test this by systematically comparing nudges to reflective interventions like thinks, boosts, and nudge+ over orders of low-carbon meals using an online experiment with 3,074 participants in the United Kingdom. We find all behavioural interventions increase intentions for climate-friendly diets, but encouraging reflection prior to nudging (“nudge+”) strengthens these treatment effects. There is no evidence of negative behavioural spillovers as measured by participants’ donations to pro-social charities. There is potential for reflective policies in promoting climate citizenship.