**1. Introduction**

Scholars and policymakers are increasingly paying attention to current ways of living and their impact on sustainability. The Paris Agreement stated the goal for society to transit towards net zero-carbon by the second half of this century, to hold the global average temperature increase well below 2 ◦C and pursue e fforts to limit it to 1.5 ◦C above the pre-industrial levels [1]. Within this context, the Intergovernmental Panel on Climate Change's (IPCC's) special report on the impacts of global warming of 1.5 ◦C recognises the changes in human behaviour and lifestyles as enabling conditions for the 1.5 ◦C consistent systems transitions' [2]. In Japan's Long-term Strategy under the Paris Agreement, it emphasises "Lifestyles Innovation" for the shift of people's daily living towards long term sustainability [3]. Lifestyle, as an instrument in sustainability, was also included in the Sustainable Development Goals, specifically Target 12.8, which specifies the significance for people to have relevant information and awareness on sustainable lifestyles [4]. Sustainable lifestyles can thus be seen both as an approach to achieve long-term sustainability and as a policy objective to ensure the delivery of high quality of life to citizens.

In sustainability research, future-oriented thinking is critical due to the scale of change needed: Systemic change instead of minor modifications [5–7]. Among the di fferent sets of approaches in future studies, foresight emerges as an inclusive policy formation process in both theory and practice, to invite non-governmen<sup>t</sup> stakeholders such as industry and expert groups to participate in giving shape to futures [8]. It is an exercise to create an improved understanding of possible future developments and forces that would be shaped by di fferent stakeholders, in order to search for alternative and desirable futures [9]. Foresight contributes to the decision-making process in three ways: Openness to di fferent futures; involvement of various stakeholders; and policy orientation [10]. Thus, in futures research, compared to the predictive forecasting approach, which focuses on the 'most likely' futures, foresight emphasises a better understanding of futures by looking for the forces that shape them; it is an action-oriented approach to shaping futures in the policymaking process. Considering those features, the foresight process has an instrumental value to improve our understanding of futures for strategy formation, and also an intrinsic value as a democratic participation process to invite more stakeholders such as the general public into the policymaking process towards the desired direction [8].

In terms of governmen<sup>t</sup> policymaking, foresight's focused topics have changed over time in line with the government's shifting societal concerns [11]. Additionally, future-oriented thinking has long been applied to the environmental field, most notably in the 1972 publication of 'Limits to Growth' and the 1988 establishment of the IPCC [11]. Recent foresight research has extended its search for long-term sustainability into transition studies, adopting more holistic thinking to include social, environmental, and economic aspects [12–14]. Due to the involvement of stakeholders with multiple knowledge fields and organisational background in the process, foresight serves as an interdisciplinary approach to generate knowledge for policy support and crosses administrative boundaries of policymaking areas and ministries [15]. Including the general public in developing a shared desirable future is also pivotal for actors to take actions to move toward a shared vision [12]. However, foresight's potential remains untapped in terms of forming alternative, progressive visions toward long-term sustainability. 'Sustainable lifestyles' as a concept can engage the general public in the policymaking process, allowing individuals to contribute to how policy can support their lifestyle aspirations within environmental limits [8]. In this context, incorporating tools from the field of foresight studies, such as a participatory policymaking process, could facilitate bottom-up policy formulation toward a long-term transition to sustainable lifestyles.

Within this context, this paper proposes key factors that could be incorporated into the participatory process with various stakeholders to envision future sustainable lifestyles. We developed these suggestions based on analysis of an expert survey on daily living and the roles of stakeholders between now and 2050. We also carried out a review of literature in the field of foresight and sustainable lifestyles. While respondents to the survey are experts from various stakeholder organisations rather than citizens, this global survey is unique in that it specifically focuses on sustainable lifestyles and enquires about stakeholders' changing roles. This paper analyses the factors related to shaping future lifestyles based on the changes identified by the expert survey. The interpretation of sustainable lifestyles di ffers from person to person and from group to group, so instead of o ffering analysis on the sustainability of the discussed changes of future lifestyles from the survey results, we provide di fferent sets of factors for the public to consider when engaging in discussions on sustainable lifestyles. We analysed the foresighted changes in the roles of di fferent stakeholders to examine whether the current mainstream government-industry-experts approach of any given foresight exercise is enough to discuss the topic of sustainable lifestyles. Moreover, foresight is a policy-oriented exercise, so understanding how stakeholders' roles change is pivotal when taking actions over a long-term transition.

Following this introduction, Section 2 describes the survey's methodology, including its design, data collection, and analysis. Section 3 reviews foresight literature to examine how foresight research and practice contribute to the policymaking process. Section 4 analyses the survey results, focusing on how lifestyles and the roles of stakeholders will change between now and 2050. Based on the analysis

of the survey results, Section 5 proposes policy formation toward long-term sustainable lifestyles under participatory foresight, and Section 6 concludes by discussing its contribution to this field of research.
