Imagine that you just found out your monthly carbon footprint based on your everyday spending. Yep, there’s a tool for that. It’s called Cogo, and it works by providing you with information about your carbon emissions within your online banking app.
Cogo’s aim is to help people to reduce their carbon emissions. And one way of doing this is to encourage people to set themselves a carbon budget. The concept is similar to a financial budget – the only difference being that you try to stay within a limit of carbon dioxide equivalent emissions each month, rather than a financial limit.
Cogo wanted to know the answer to the following question: what is the best way of encouraging people to set a lower, more ambitious carbon budget for themselves?
One approach might be to use defaults – a tried-and-tested formula among behavioural scientists that has been applied successfully in a range of domains, for example when the UK switched to auto-enrolment in pensions in 2012. Could we therefore just give everyone a default target of a 10% reduction on their current carbon footprint (which they can adjust if they choose)?
An alternative approach, also based on previous behavioural science research, might be to use social reference groups. In other words we could tell people the average carbon footprint of others who they might relate to, like people in the UK, people who spend the same amount as them, or people who use the same bank as them. Would this encourage people to set a lower carbon budget?
To find out, we invited more than 2,000 people to take part in an online study and randomly assigned them to seven conditions. In the control condition, they were told their estimated carbon footprint and asked to set themselves a carbon budget.
In the treatment conditions, we gave participants information about the average carbon footprint of different groups of people (people in the UK, people who spend the same as them, and people who use the same bank as them).
But there was a twist. Some people saw lower values for these averages than others (e.g. the UK average was 1,058kg in one condition and 941kg in another). We did this across each of the three comparison groups in order to test the effect of this default value (1,058kg vs 941kg) – as shown in the table below.
Changing this default value and the social reference group between treatment conditions enabled us to test the relative effectiveness of these interventions. Which would most encourage people to set a lower carbon budget for themselves?
Our first finding was that giving people some information about the average carbon footprint of others was more effective than giving them no information at all. In other words, participants in all of our treatment conditions on average set lower carbon budgets for themselves (1,015kg) than those in our control condition (1,070kg) (p < .01).
Our second finding was that it did not really matter who the social reference group was. There was no meaningful difference between the budgets set by people who were told the average footprint apparently belonged to people in the UK, people with similar spending to them, or customers at the same bank (p = .815).
Instead, we found that our defaults mattered a lot. Much more than our social reference groups. As shown in the graph below, participants who were told that the average carbon footprint of others was 941kg (rather than 1,058kg) set a much lower carbon budget (p < .0001).
Figure 1. Carbon Budgets by Treatment Conditions The plot shows the average carbon budgets set by individuals in our control group and each of our treatment conditions. Bars in pink show treatments with a high default value (1,058kg) while bars in green show treatments with a low default value (941kg). Error bars represent the standard error in each group.
So in summary, what mattered most was the default itself, which provided a target for each individual to aim for, rather than who exactly the social reference group was. This is useful because it means that the relevant reference group can be changed in order to create more or less ambitious targets, without worrying about whether some efficacy will be lost as a result of switching the group (as opposed to changing the default).
As we said at the start, if you’d like to find out your own monthly carbon footprint (based on your spending) and set yourself a carbon budget, there’s a tool for that. It’s called Cogo.
