**4. Discussion**

The global community now has access to a broad range of studies confirming that lifestyle change across all consumption domains will be needed to keep climate change within 1.5 degrees of warming. In this paper we confirmed that the majority of NDCs do not significantly include lifestyle change, in particular the large emitters (USA, Australia, Singapore, India, Russia). There are signs that this is changing, and some more recent NDCs and climate change strategies do include demand-side measures including those related to indirect emissions (food, goods and services). Given the limited time left to change course, climate change stakeholders must address barriers to addressing the full range of mitigation measures recommended by the IPCC, including significant demand-side measures. Table 3 provides an overview of potential barriers that may explain the trends in Section 3.


**Table 3.** Potential barriers to inclusion of demand-side mitigation measures in climate policy. **Table 3.** *Cont.*


### **5. Conclusions: Recommendations**

The policy cycle framework outlined in Section 1 shows how environmental policies, including those on climate action, should be developed and monitored based on scientific evidence. Climate policies, such as NDCs, should apply the full range of scientifically identified climate change mitigation strategies in order to reduce emissions sufficiently and efficiently, and to more accurately monitor the combined commitments. However, there are a range of barriers when it comes to demand-side policies. In order to overcome them, researchers and policymakers need to collaborate far more to increase the uptake of methodological frameworks that can quickly and comprehensively support countries in selecting the right policy goals and instruments. Below are some recommendations on potential solutions to address the barriers identified in Section 4.

The accounting and reporting methodology plays a fundamental role, and is currently not conducive to demand-side or extraterritorial emission reductions. Despite this, indirect emissions, or footprints, are increasingly referred to in climate change mitigation strategies (Korea, France, Austria, Japan) and can be powerful strategies to bridge the gap to climate

change goals. However, the pressure to deliver on domestic emission reductions, and concerns about double counting extraterritorial emissions remain unresolved. Therefore, member States should agree on a globally accepted accounting methodology that enables them to report on indirect extraterritorial emission reductions while addressing double counting concerns.

Second, a move away from national borders would help optimize climate mitigation measures and inclusion of demand-side measures. The globalized nature of our supply chains has stifled the optimization of climate change action. Instead of aiming for the largest mitigation opportunities, countries are focused on domestic mitigation, with the exception of the EU. The EU has shown that submitting one common regional NDC can encourage inclusion of supply chain emissions or footprints, since a large percentage of EU countries' extraterritorial emissions are still within the EU [29] and hence contribute to the common emission reduction target. Climate policymakers should consider the transboundary impacts and mitigation opportunities related to domestic demand within their NDCs. There is some precedent for this. The international nature of emissions is already acknowledged in the Paris Agreement through offsets, where countries can be credited for reducing extraterritorial emissions through offset programs. Article 14 of the Paris Agreement opens doors for this under the terms of "collective progress" and "enhancing international cooperation for climate action".

Third, there could be more official guidance on NDC scope, particularly on linking the NDCs to the IPCC findings. The inconsistencies between NDCs make it difficult to monitor progress against mitigation pathways and compare countries. More guidance could be provided on how to arrange demand-side climate mitigation actions according to existing or additional sectoral categorization. This could encourage countries to reflect existing measures already in national policy in the NDC, and also provide a nudge to include demand-side mitigation strategies. Climate mitigation is generally categorized according to energy, transport, industry, agriculture, Land Use, Land-Use Change and Forestry (LULUCF), and waste; demand-side measures could be added as a cross-cutting sector or as subsectors in the existing sectors.

Related to the above, a strengthening of the science–policy interface could be achieved through dedicated training for NDC developers on how to include demand-side and extraterritorial mitigation measures recommended by the IPCC. The decision to adopt the Paris Agreement (1/CP.2) included a paragraph (Article II/21) under the article covering NDCs that the IPCC "provide a special report in 2018 on the impacts of global warming of 1.5 ◦C above pre-industrial levels and related global greenhouse gas emission pathways"). There is no mention of how this report's findings should be used in the design of nationally determined contributions going forward. Training for NDC developers can help them address domestic political and strategic concerns, while also employing the full spectrum of climate change mitigation options identified through international scientific assessment.

Lastly, countries need nationally tailored support to establish the evidence base for, and design of, demand-side policies. There is an urgen<sup>t</sup> need for more country level assessments of options for demand-side climate change mitigation to even out the asymmetry in availability of such assessments for countries. While all countries should reduce supply side and territorial emissions, there may be cost effective, fast options available to them that are either indirect or occurring abroad in upstream supply chains or both. National studies should provide a quantification of the demand-side mitigation options, and also seek solutions to harmonize demand-side options with national political and economic contexts. This is particularly urgen<sup>t</sup> in developing countries undergoing rapid growth and hence holding significant future cumulative responsibility for GHG emissions under business-as-usual projections.

### **6. Future Outlook**

From an academic point of view, findings from different multi-regional input–output assessments are converging [84], institutional and governance requirements are clear [85], implications of consumption-based accounting are understood [86], and case studies from policy practice exist [30]. In short, the scientific domain of carbon footprinting and sustainable lifestyles policy has reached a level of maturity and agreemen<sup>t</sup> to be ripe for application in climate policy.

Member States have already agreed to including a different footprint metric, the material footprint, in another international agreement—the Sustainable Development Goals indicator framework. It serves as an indicator for SDG 8.4 on resource efficient growth, and SDG 12.2 on sustainable resource management. The metadata include a methodology, based on the multi-regional input output framework [87], under the caretaker organization, the UN Environment Programme. Its inclusion in the SDGs is not binding, since all member States can select their own indicators, and the goals themselves and reporting processes are also voluntary. However, the endorsement of this methodology and survival in a multilateral agreemen<sup>t</sup> process dependent on consensus give some hope that carbon footprints can also be integrated into the methodological and reporting framework under the Paris Agreement. Linkages between climate policy and the Sustainable Development Goals may also create synergies that enable demand-side mitigation strategies [88].

Climate policy and research has made promising progress in the spirit of the Paris Agreement's statement that "*sustainable lifestyles and sustainable patterns of consumption and production, with developed country parties taking the lead, play an important role in addressing climate change".* Six years into the Paris Agreement implementation, it is urgen<sup>t</sup> that all countries apply the best available knowledge on the full range of climate mitigation options to the NDCs. Sustainable lifestyles are considered essential to achieving targets, therefore the barriers to including them in NDCs and national climate policies need to be further investigated so that the solutions can be shaped and implemented well before the global carbon budget is depleted.

**Author Contributions:** Conceptualization, J.S.; data curation, J.S.; formal analysis, J.S.; investigation, J.S.; methodology, J.S. and M.L.; supervision, M.L.; validation, M.L.; writing—original draft, J.S.; writing—review and editing, M.L. and Y.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This publication was supported by the Environment Research and Technology Development Fund (S-16-3: JPMEERF16S11630) of the Environmental Restoration and Conservation Agency, Japan.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

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