**6. Conclusions**

This paper argued that policy discussion on SCP is a major expression of the sustainability agenda, and that this discourse has expanded from pollution prevention (SCP 1.0) to lifecycles (SCP 2.0), then to transition (SCP 3.0). For policy discussions on sustainability, it is very important to better understand how SCP is discussed in the different contexts of SCP 1.0, SCP 2.0 and SCP 3.0. Each country and communitytable has different policy priorities [106], and consequently, discussions tend to focus on one of the three SCP

phases—SCP1.0, 2.0 and 3.0—or as a combination of these three versions. We could in fact have a hybrid concept, whereby three different but related contexts of environmental policy development endeavor to achieve SCP in a phased manner from SCP 1.0 to SCP 3.0. This could be especially pertinent for emerging economies.

One of the major features of recent international policy agreements is that they have set ambitious long and mid-term goals based on the concept of planetary boundaries. This resulted in an expansion of policy domain from environmental sustainability to socio-technical systems change (SCP 3.0). These changes in emphasis in policy goals and approaches also resulted in the need for a fresh approach for SCP policy design.

The challenge facing SCP policy design in this context is the development of model cases, and a social image or vision. Emerging opportunities and challenges for policy design for SCP 3.0 include: (1) envisioning concrete images of a society that has successfully met its mid-term and long-term goals, (2) policy support for learning from model cases, experimental projects, and new businesses to achieve a long-term and mid-term vision, (3) facilitating creative process among stakeholders, and (4) examination of social implications of innovation towards decarbonization, digitalization, and transition to sustainable lifestyles and infrastructure. To deepen the debate on SCP policies required in the future, it is necessary to change our way of thinking on environmental policies. As a policy design approach in response to these challenges and opportunities, the paper proposed the concept of Envisioning-based Policy Making (EnBPM). In the era of SCP 3.0, policy design and scientific research on SCP can provide rich opportunities and challenges to bring together creative visions, future scenarios, social experimentation, stakeholder engagement, urban and spatial planning, new indicator development, lifestyles and social sustainability, and new business model development. Conventional regulations and economic tools must work to introduce a new approach and innovation into lifestyles and infrastructure [107]. We need to develop a social business model and promote public and private investment to facilitate model cases which can enhance storylines for sustainable transition. We must come up with new business or social model development and social designs within planetary boundaries, and incorporate them into the central agenda of SCP policy. Communication and decision-support tools will also play an important role to promote stakeholder collaboration and dialogue. In that sense, there are rapidly emerging opportunities for collaboration between policy design and scientific research on SCP for envisioning and developing model cases which can generate compelling storylines for SCP 3.0.

**Author Contributions:** Formal analysis, Investigation, Supervision, Writing—original draft, Y.H.; Conceptualization, Y.H., T.T., and R.K.; Writing—review & editing, T.T. and R.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This paper was developed based on the research funded by the Environment Research and Technology Development Fund (S-16-3: JPMEERF16S11630, S-16-2: JPMEERF16S11620) of the Environmental Restoration and Conservation Agency, Japan.

**Acknowledgments:** The authors would like to express their appreciation to Emma Fushimi of IGES for her careful editing and proof reading of the entire manuscript as well as to Chen Liu of IGES for her review and insightful comments to improve the earlier draft.

**Conflicts of Interest:** The authors declare no conflict of interest.
