Lifestyle changes are an essential, complementary measure for reducing greenhouse gas emissions and, therefore, also an important ingredient to climate policy. Computational models of lifestyle changes and their contribution to climate change mitigation can provide valuable insights in support of decision-making by individuals and policymaking. In this Perspective, we examine four modelling approaches with this in mind: input-output analysis, life cycle assessment, integrated assessment models, and agent-based models. They have different strengths and weaknesses related to spatial and temporal scales, sector representation, consumer heterogeneity, and impact assessment. Despite their differences, all are ultimately suitable for modelling different types of climate-friendly lifestyle changes – from sufficiency over efficiency to modal shift measures. Each modelling approach provides useful, albeit partial, insights into lifestyle changes. The identified challenges call for both continual refinements within individual model frameworks and hybrid methods that bridge their respective strengths and allow for representing lifestyle changes more comprehensively. Together, they inform about the theoretical mitigation potential, initiative feasibility, behavioural plasticity, and policy effectiveness of lifestyle changes. Ultimately, cross-disciplinary collaboration will be key to designing lifestyle-focused policies that are both impactful and acceptable.

Nuts are considered an important protein source in sustainable dietary patterns but are seldom studied in detail. Here a multi-criteria decision analysis was used to rank 10 nuts and seeds against 11 environmental, nutritional, and social criteria and provide greater insight into the sustainability impacts of this food group. Weights were defined based on correlation and variance between indicator values, and values were aggregated with a partially non-compensatory method. Several sensitivity analyses tested various sources of uncertainty through the use of country-level data, the use of a fully compensatory aggregation method, and changes to criteria weights. Walnuts and sunflower seeds performed consistently well across sustainability criteria and were ranked in the top two positions in the baseline assessment and most sensitivity analyses. In contrast, cashews performed relatively poorly across most criteria, and were ranked last. Dietary shifts in favor of more sustainable nuts can improve the overall environmental, nutritional and social impacts of nut production and consumption by an average of 23%. Although increasing consumption of walnuts and sunflower seeds may lead to improved sustainability outcomes for total global nut consumption, more research is needed to deepen the understanding of the complex socio-economic factors impacting nut and seed sustainability. The social risk assessment method used in this study can also inform future social impact measurement methods for other food groups.