Belief in scientific consensus can spark action: There's a lot of complexity and nuance within climate change projections - and for some people the overall agreement gets lots. If you need to convince individuals - reinforce the consensus among researchers in the facts. For example - if encouraging XYZ, remind users or potential customers that XX% of researchers agree on XYZ.
Rationale - see paper on scientific consensus as a "gateway belief"
Social networks and systems will play a large role in motivating larger changes: One of the largest predictors of behavior change (beyond climate) is what behaviors peers are doing and support. For example, in order to spark bigger changes - i.e. building climate neutral cities, use consider using the coalition model to leverage the positive peer effects and accountability within a social network.
Rationale - see paper systems analysis of climate actions and social networks
Individual experience with climate change and motivate behavior change - but may see it in terms of economic or practical issues, rather than climate concerns: As individuals experience climate change and its impacts have effects on their livelihoods - individuals will become more likely to take actions to prevent or mitigate effects. For example, farmers who were experiencing climate impacts on their crops and believed in climate change were more likely to take adaptive actions.
Rationale- see paper outlining farm actions and climate beliefs