Table 1.

Interventions, theoretical frameworks, and brief descriptions^{38,39,46,76–87}

Intervention	Theoretical framework	Description
Dynamic social norms	Sparkman and Walton (2017)17	Informs participants of how country-level norms are changing and “more and more people are becoming concerned about climate change”, suggesting that people should take action.
Work together norm	Howe et al. (2021)77	Combines referencing a social norm (i.e., “a majority of people are taking steps to reduce their carbon footprint”) with an invitation to “join in” and work together with fellow citizens toward this common goal.
Effective collective action	Goldenberg et al. (2018)77; Lizzio-Wilson et al. (2021)79	Features examples of successful collective action that have had meaningful effects on climate policies (e.g., protests) or have solved past global issues (e.g., the restoration of the ozone layer).
Psychological distance	Jones et al. (2017)80	Frames climate change as a proximal risk by using examples of recent natural disasters caused by climate change in each participants’ nation and prompts them to write about the climate impacts on their community.
System justification	Feygina et al. (2010)46	Frames climate change as threatening to the way of life to each participant’s nation, and makes an appeal to climate action, as the patriotic response.
Future-self continuity	Hershfield et al. (2012)81	Emphasizes the future self-continuity by asking each participant to project themselves into the future and write a letter addressed to themselves in the present, describing the actions they would have wanted to take regarding climate change.
Negative emotions	Chapman et al. (2017)82	Exposes participants to ecologically valid scientific facts regarding the impacts of climate change framed in a ‘doom and gloom’ style of messaging that were drawn from different real-world news and media sources.
Pluralistic ignorance	Geiger and Swim (2016)83	Presents real public opinion data collected by the United Nations that shows what percentage of people in each participant’s country agree that climate change is a global emergency.
Letter to future generation	Shrum (2021)87; Wickersham et al. (2020)84	Emphasizes how one’s current actions impact future generations by asking participants to write a letter to a socially close child who will read it in 25 years when they are an adult, describing current actions towards ensuring a habitable planet.
Binding moral foundations	Wolsko et al. (2016)38	Invokes authority (e.g., “From scientists to experts in the military, there is near universal agreement”), purity (e.g., keep our air, water, and land pure), and ingroup-loyalty (e.g., “it is the American solution”) moral foundations.
Scientific consensus	van der Linden et al. (2015)39, van der Linden (2021)85; Rode et al. (2021)86	Informs participants that “99% of expert climate scientists agree that the Earth is warming, and climate change is happening, mainly because of human activity”.