As primates, we evolved to work cooperatively to defend territory and sustainably harvest food and resources for the group, all while ensuring enough genetic diversity to procreate. Anthropological experiments show us that, on average, any one individual can maintain stable relationships with 150 other people – a phenomenon known as “Dunbar’s number” . Beyond that social relationships begin to break down, undermining an individual’s ability to trust and rely on the actions of others to achieve collective long-term goals.

Unfortunately, this capacity to plan to ensure a future outcome breaks down when large-scale collective action is needed – as is the case with climate change. As individuals, we know what we can do about climate change. But addressing the issue also requires collective action on a scale that exceeds our evolutionary capacities. The larger the group, the more challenging it gets. Remember the bystander effect?

We can imagine and predict multiple, complex outcomes and identify actions needed in the present to achieve desired outcomes in the future. And individually we often prove able to act on these plans. We invest in retirement accounts and buy insurance, for example, as ways to counter our short-term interests over the long-term.

Recognising the power of small groups, Exposure Labs, the film company behind Chasing Ice and Chasing Coral, is using its films to mobilise communities to take local action on climate change. For example, in South Carolina, a US state rife with leaders who deny climate change, Exposure Labs shows a film to get a conversation started, inviting people from various interest groups – like the agricultural, fisheries, and tourism industries – to talk about how climate change affects them personally. They then work these small groups to identify practical actions that can be taken immediately at the local level to make an impact – something that helps generate the political pressure necessary to compel lawmakers to pass relevant local or state-wide legislation. When local communities shape the narrative around individual interests, people are less likely to succumb to the bystander effect and more likely to engage.

These approaches use a couple of other psychological strategies, too. First, when small groups are involved in coming up with solutions themselves, they experience the endowment effect: when we own something (even an idea), we tend to value it more. Second, social comparison: we tend to evaluate ourselves by looking at others. If we’re surrounded by other people in a group who are taking action on climate change, we’re more likely to do the same. This is also the impetus behind programmes like comparing energy consumption from household to household in a community. Research shows that when people compare their energy use with their neighbours’ via statements on their energy bills they are more likely to reduce energy consumption.

Of all our cognitive biases, however, the framing effect is one of the strongest affecting our decision-making processes. Humans are more likely to change behaviour when challenges are framed positively, instead of negatively. In other words, how we communicate about climate change influences how we respond. People are more likely to act in relation to a positive frame (“a clean energy future will save X number of lives”) versus a negative statement (“we’re going to go extinct due to climate change”).