There is a growing recognition of the urgent need to change citizens’ lifestyles to realise decarbonised societies. Consumption-based accounting (carbon footprinting) is a helpful indicator for measuring the impacts of peoples’ consumption on climate change by capturing both direct and embedded carbon emissions. However, while carbon footprinting can propose impactful behaviour changes to reduce carbon footprints immediately, it may deflect people’s attention from the much needed but time-consuming efforts to reshape the “systems of provisions” to enable decarbonised living. To propose a more constructive application of carbon footprinting, the paper examines the three cases of using carbon footprinting derived from the 1.5-degree lifestyles project, including citizens’ discussions and experiments in six cities in 2020 and 2021, citizens’ workshops contributing to the local policy development in 2022, and lectures and mini-workshops since 2020. Based on the examination of the cases, the article argues the broader purposes of using scientific data in citizens’ engagement in climate actions, namely to help deepen understanding of the systemic causes of the incumbent carbon-intensive society, to guide discussions on the desired conditional changes to support lifestyles shifts, and to help identify possible risks or negative consequences of changes to specific groups in society. These benefits contribute to developing relevant stakeholders’ essential capacities to promote changes at the individual, collective and public levels toward decarbonised societies.