Psychological interventions increase motivation to exert effort to mitigate climate change

To limit the devastating effects of climate change, individuals need to engage in pro-environmental behaviours. Psychological interventions could be an effective tool for promoting such actions. However, previous work has measured the effectiveness of interventions on self-reported pro-environmental attitudes and neglected impacts on behaviour. Pro-environmental behaviours, such as cycling, are often more effortful than alternative behaviours, such as driving. Therefore, assessing whether interventions are effective requires measuring how motivated people are to exert effort to benefit the climate. Here, we developed a novel Pro-Environmental Effort Task (PEET) to examine the effectiveness of 11 different psychological interventions in six representative samples from six countries (total n=3,055). Using computational modelling, we precisely identified a small number of interventions that increase motivation to exert effort specifically to benefit a climate charity, relative to a matched non-environmental cause. Overall, we also observed reduced motivation to benefit the climate charity in people with lower belief in climate change or support for pro-environmental policies. Our results reveal the individual predictors of pro-environmental motivation and identify psychological interventions that promote relative willingness to exert effort to protect the planet.