Editing IPCC:AR6/WGIII/Chapter-12 (section)

=== 12.6.1 Cross-sectoral Perspectives on Mitigation Action ===

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Chapters 5 to 11 present mitigation measures applicable in individual sectors, and potential co-benefits and adverse side effects [[#footnote-000|4]] of these individual measures. This section builds on the sectoral analysis of mitigation action from a cross-sectoral perspective. Firstly, [[#12.6.1.1|Section 12.6.1.1]] brings together some of the observations presented in the sectoral chapters to show how different mitigation actions in different sectors can contribute to the same co-benefits and result in the same adverse side effects, thereby demonstrating the potential synergistic effects. The links between these co-benefits and adverse side effects and the SDGs is also demonstrated. In [[#12.6.1.2|Section 12.6.1.2]] , the focus turns from sector-specific mitigation measures to mitigation measures which have cross-sectoral implications, including measures that have application in more than one sector and measures where implementation in one sector impacts on implementation in another. Finally, [[#12.6.1.3|Section 12.6.1.3]] notes the cross-sectoral relevance of a selection of general-purpose technologies, a topic that is covered further in Chapter 16.

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==== 12.6.1.1 A Cross-sectoral Perspective on Co-benefits and Adverse Side Effects of Mitigation Measures, and Links with the SDGs ====

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A body of literature has been developed which addresses the co-benefits of climate mitigation action ( [[#Karlsson--2020|Karlsson et al. 2020]] ). Adverse side effects of mitigation are also well documented. Co-benefits and adverse side effects in individual sectors and associated with individual mitigation measures are discussed in the individual sector chapters (Sections 5.2, 6.7.7, 7.4, 7.6, 8.2, 8.4, 9.8, 10.1.1 and 11.5.3), as well as in previous IPCC General and Special Assessment reports. The term ‘co-impacts’ has been proposed to capture both the co-benefits and adverse side effects of mitigation. An alternative framing is one of multiple objectives, where climate change mitigation is placed alongside other objectives when assessing policy decisions ( [[#Ürge-Vorsatz--2014|Ürge-Vorsatz et al. 2014]] ; [[#Mayrhofer--2016|Mayrhofer and Gupta 2016]] ; [[#Cohen--2017|Cohen et al. 2017]] ; [[#Bhardwaj--2019|Bhardwaj et al. 2019]] ).

The identification and assessment of co-benefits has been argued to serve a number of functions ( [[IPCC:Wg3:Chapter:Chapter-1#1.4|Section 1.4]] ) including using them as leverage for securing financial support for implementation, providing justification of actions which provide a balance of both short- and long-term benefits and obtaining stakeholder buy-in ( ''robust evidence'' , ''low agreement'' ) ( [[#Karlsson--2020|Karlsson et al. 2020]] ). Assessment of adverse side effects has been suggested to be useful in avoiding unforeseen negative impacts of mitigation and providing policy- and decision-makers with the information required to make informed trade-offs between climate and other benefits of actions ( [[#Ürge-Vorsatz--2014|Ürge-Vorsatz et al. 2014]] ; [[#Bhardwaj--2019|Bhardwaj et al. 2019]] ; [[#Cohen--2019|Cohen et al. 2019]] ) ( ''high evidence'' , ''low agreement'' ).

Various approaches to identifying and organising co-impacts in specific contexts and across sectors have been proposed towards providing more comparable and standardised analyses. However, consistent quantification of co-impacts, including cost-benefit analysis, and the utilisation of the resulting information, remain a challenge ( [[#Ürge-Vorsatz--2014|Ürge-Vorsatz et al. 2014]] ; [[#Floater--2016|Floater et al. 2016]] ; [[#Mayrhofer--2016|Mayrhofer and Gupta 2016]] ; [[#Cohen--2019|Cohen et al. 2019]] ; [[#Karlsson--2020|Karlsson et al. 2020]] ). This challenge is further exacerbated when considering that co-impacts of a mitigation measure in one sector can either enhance or reduce the co-impacts associated with mitigation in another, or the achievement of co-benefits in one geographic location can lead to adverse side effects in another. For example, the production of lithium for batteries for energy storage has the potential to contribute to protecting water resources and reducing wastes associated with coal-fired power in many parts of the world, but mining of lithium has the potential for creating water and waste challenges if not managed properly ( [[#Agusdinata--2018|Agusdinata et al. 2018]] ; [[#Kaunda--2020|Kaunda 2020]] ).

While earlier literature has suggested that co-impacts assessments can support adoption of climate mitigation action, a more recent body of literature has suggested limitations in such framing ( [[#Ryan--2015|Ryan 2015]] ; [[#Bernauer--2016|Bernauer and McGrath 2016]] ; [[#Walker--2018|Walker et al. 2018]] ). Presenting general information on co-impacts as a component of a mitigation analysis does not always lead to increased support for climate mitigation action. Rather, the most effective framing is determined by factors relating to local context, type of mitigation action under consideration and target stakeholder group. More work has been identified to be required to bring context into planning co-impacts assessments and communication thereof ( [[#Ryan--2015|Ryan 2015]] ; [[#Bernauer--2016|Bernauer and McGrath 2016]] ; [[#Walker--2018|Walker et al. 2018]] ) ( ''low evidence'' , ''low agreement'' ).

An area where the strong link between the cross-sectoral co-impacts of mitigation action and global government policies is being clearly considered is in the achievement of the SDGs ( [[#Obergassel--2017|Obergassel et al. 2017]] ; [[#Doukas--2018|Doukas et al. 2018]] ; [[#Markkanen--2019|Markkanen and Anger-Kraavi 2019]] ; Smith et al. 2019; [[#van%20Soest--2019|van Soest et al. 2019]] ) (Chapters 1 and 17, individual sectoral chapters). Figure 12.9 demonstrates these relationships from a cross-sectoral perspective. It shows the links between sectors which give rise to emissions, the mitigation measures that can find application in the sector, and co-benefits and adverse side effects of mitigation measures and the SDGs (noting that the figure is not intended to be comprehensive). Such a framing of co-impacts from a cross-sectoral perspective in the context of the SDGs could help to further support climate mitigation action, particularly within the context of the Paris Agreement ( [[#Gomez-Echeverri--2018|Gomez-Echeverri 2018]] ) ( ''medium evidence'' , ''medium agreement'' ). Literature sources utilised in the compilation of this diagram are presented in Supplementary Material 12.SM.3.

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[[File:c941fa42bb9802b82a6cf08fb78d4d14 IPCC_AR6_WGIII_Figure_12_9.png]]

'''Figure 12.9 | Co-benefits and adverse side effects of mitigation actions with links to the SDGs.''' The inner circle represents the sectors in which mitigation occurs. The second circle shows different generic types of mitigation actions (A to G), with the symbols showing which sectors they are applicable to. The third circle indicates different types of climate related co-benefits (green letters) and adverse side effects (red letters) that may be observed as a result of implementing each of the mitigation actions. Here I relates to climate resilience, II-IV economic co-impacts, V-VII environmental, VIII-XII social, and XIII political and institutional. The final circle maps co-benefits and adverse side effects relevant to the SDGs. Source: re-used with permission from [[#Cohen--2021|Cohen et al. (2021)]] .

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==== 12.6.1.2 Mitigation Measures from a Cross-sectoral Perspective ====

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Three aspects of mitigation from a cross-sectoral perspective are considered, following [[#Barker--2007|Barker et al. (2007)]] :

• mitigation measures used in more than one sector;

'''•''' implications of mitigation measures for interaction and integration between sectors; and

• competition among sectors for scarce resources.

A number of mitigation measures find application in more than one sector. Renewable energy technologies such as solar and wind may be used for grid electricity supply, as embedded generation in the buildings sector and for energy supply in the agriculture sector ( [[#Shahsavari--2018|Shahsavari and Akbari 2018]] ) (Chapters 6, 7 and 8). Hydrogen and fuel cells, coupled with low-carbon energy technologies for producing the hydrogen, are being explored in transport, urban heat, industry and for balancing electricity supply ( [[#Dodds--2015|Dodds et al. 2015]] ; [[#Staffell--2019|Staffell et al. 2019]] ) (Chapters 6, 8 and 11). Electric vehicles are considered an option for balancing variable power ( [[#Kempton--2005|Kempton and Tomić 2005]] ; [[#Liu--2019|Liu and Zhong 2019]] ). Carbon capture and storage (CCS) and carbon capture and utilisation (CCU) have potential application in a number of industrial processes (cement, iron and steel, petroleum refining and pulp and paper) ( [[#Leeson--2017|Leeson et al. 2017]] ; [[#Garcia--2019|Garcia and Berghout 2019]] ) (Chapters 6 and 11) and the fossil fuel electricity sector (Chapter 6). When coupled with energy recovery from biomass, CCS can provide a carbon sink (BECCS) ( [[#12.5|Section 12.5]] ). On the demand side, energy efficiency options find application across the sectors (Chapters 6, 8, 9, 10, and 11), as do reducing demand for goods and services (Chapter 5) and improving material efficiency ( [[IPCC:Wg3:Chapter:Chapter-11#11.3.2|Section 11.3.2]] ).

A range of examples where mitigation measures result in cross-sectoral interactions and integration is identified. The mitigation potential of electric vehicles, including plug-in hybrids, is linked to the extent of decarbonisation of the electricity grid, as well as to the liquid fuel supply emissions profile ( [[#Lutsey--2015|Lutsey 2015]] ). Making buildings energy positive, where excess energy is used to charge vehicles, can increase the potential of electric and hybrid vehicles ( [[#Zhou--2019|Zhou et al. 2019]] ). Advanced process control and process optimisation in industry can reduce energy demand and material inputs ( [[IPCC:Wg3:Chapter:Chapter-11#11.3|Section 11.3]] ), which in turn can reduce emissions linked to resource extraction and manufacturing. Reductions in coal-fired power generation through replacement with renewables or nuclear power result in a reduction in coal mining and its associated emissions. Increased recycling results in a reduction in emissions from primary resource extraction. CCU can contribute to the transition to more renewable energy systems via power-to-X technologies, which enables the production of CO 2 -based fuels/e-fuels and chemicals using carbon dioxide and hydrogen ( [[#Breyer--2015|Breyer et al. 2015]] ; [[#Anwar--2020|Anwar et al. 2020]] ). Certain emissions reductions in the AFOLU sector are contingent on energy sector decarbonisation. Trees and green roofs planted to counter urban heat islands reduce the demand for energy for air conditioning and simultaneously sequester carbon ( [[#Kim--2018|Kim and Coseo 2018]] ; [[#Kuronuma--2018|Kuronuma et al. 2018]] ). Recycling of organic waste avoids methane generation if the waste would have been disposed of in landfill sites, can generate renewable energy if treated through anaerobic digestion, and can reduce requirements for synthetic fertiliser production if the nutrient value is recovered ( [[#Creutzig--2015|Creutzig et al. 2015]] ). Liquid transport biofuels link to the land, energy and transport sectors ( [[#12.5.2|Section 12.5.2]] .2).

Demand-side mitigation measures, discussed in Chapter 5, also have cross-sectoral implications which need to be taken into account when calculating mitigation potentials. Residential electrification has the potential to reduce emissions associated with lighting and heating, particularly in developing countries where these are currently met by fossil fuels and using inefficient technologies, but will increase demand for electricity (Chapters 5 and 8 and Sections 6.6.2.3 and 8.4.3.1). Many industrial processes can also be electrified in the move away from fossil reductants and direct energy carriers (Chapter 11). The impact of electrification on electricity sector emissions will depend on whether electricity generation is based on fossil fuels in the absence of CCS or low-carbon energy sources (Chapter 5).

At the same time, saving electricity in all sectors reduces the demand for electricity, thereby reducing mitigation potential of renewables and CCS. Demand-side flexibility measures and electrification of vehicle fleets are supportive of more intermittent renewable energy supply options (Sections 6.3.7, 6.4.3.1 and 10.3.4). Production of maize, wheat, rice and fresh produce requires lower energy inputs on a lifecycle basis than poultry, pork and ruminant-based meats ( [[#Clark--2017|Clark and Tilman 2017]] ) ( [[#12.4|Section 12.4]] ). It also requires less land area per kilocalorie or protein output ( [[#Clark--2017|Clark and Tilman 2017]] ; Poore and Nemecek 2018), so replacing meat with these products makes land available for sequestration, biodiversity or other societal needs. However, production of co-products of the meat industry, such as leather and wool, is reduced, resulting in a need for substitutes. Further discussion and examples of cross-sectoral implications of mitigation, with respect to cost and potentials, are presented in [[#12.2|Section 12.2]] . One final example on this topic included here is that of circular economy ( [[#_idTextAnchor014|Box 12.4]] ).

Finally, in terms of competition among sectors for scarce resources, this issue is often considered in the assessments of mitigation potentials linked to bioenergy and diets (vegetable vs animal food products), land use and water ( ''robust evidence'' , ''high agreement'' ) ( [[#12.5|Section 12.5]] and Cross-Working Group Box 3 in this Chapter). It is, however, also relevant elsewhere. Constraints have been identified in the supply of indium, tellurium, silver, lithium, nickel and platinum that are required for implementation of some specific renewable energy technologies ( [[#Watari--2018|Watari et al. 2018]] ; [[#Moreau--2019|Moreau et al. 2019]] ). Other studies have shown constraints in supply of cobalt, one of the key elements used in production of lithium-ion batteries, which has been assessed for mitigation potential in energy, transport and buildings sectors ( ''medium evidence'' , ''high agreement'' ) (Jaffe 2017; [[#Olivetti--2017|Olivetti et al. 2017]] ), although alternatives to cobalt are being developed ( [[#Olivetti--2017|Olivetti et al. 2017]] ; [[#Watari--2018|Watari et al. 2018]] ).

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