Editing IPCC:AR6/WGIII/Chapter-3 (section)

==== 3.4.1.3 Linkages Among Sectors ====

<div id="h3-9-siblings" class="h3-siblings"></div>

Mitigation in one sector can be dependent upon mitigation in another sector, or may involve trade-offs between sectors. Mitigation in energy demand often includes electrification ( [[#Pietzcker--2014|Pietzcker et al. 2014]] ; [[#Luderer--2018|Luderer et al. 2018]] ; [[#Sharmina--2020|Sharmina et al. 2020]] ; [[#DeAngelo--2021|DeAngelo et al. 2021]] ), however such pathways only result in reduced emissions ''if'' the electricity sector is decarbonised ( [[#Zhang--2020|Zhang and Fujimori 2020]] ) (Chapter 12). Relatedly, the mitigation potential of some sectors (e.g., transportation) depends on the decarbonisation of liquid fuels, for example, through biofuels ( [[#Pietzcker--2014|Pietzcker et al. 2014]] ; [[#Wise--2017|Wise et al. 2017]] ; [[#Sharmina--2020|Sharmina et al. 2020]] ) (Chapter 12). In other cases, mitigation in one sector results in reduced emissions in another sector. For example, increased recycling can reduce primary resource extraction; planting trees or green roofs in urban areas can reduce the energy demand associated with space cooling (Chapter 12).

Mitigation in one sector can also result in additional emissions in another. One example is electrification of end use which can result in increased emissions from energy supply. However, one comparitively well-researched example of this linkage is bioenergy. An increase in demand for bioenergy within the energy system has the potential to influence emissions in the AFOLU sector through the intensification of land and forest management and/or via land-use change ( [[#Daioglou--2019|Daioglou et al. 2019]] ; [[#Smith--2019|Smith et al. 2019]] ; [[#Smith--2020a|Smith et al. 2020a]] ; [[#IPCC--2019a|IPCC 2019a]] ). The effect of bioenergy and BECCS on mitigation depends on a variety of factors in modelled pathways. In the energy system, the emissions mitigation depends on the scale of deployment, the conversion technology, and the fuel displaced ( [[#Calvin--2021|Calvin et al. 2021]] ). Limiting or excluding bioenergy and/or BECCS increases mitigation cost and may limit the ability of a model to reach a low warming level ( [[#Edmonds--2013|Edmonds et al. 2013]] ; [[#Calvin--2014b|Calvin et al. 2014b]] ; [[#Luderer--2018|Luderer et al. 2018]] ; [[#Muratori--2020|Muratori et al. 2020]] ). In AFOLU, bioenergy can increase or decrease terrestrial carbon stocks and carbon sequestration, depending on the scale, biomass feedstock, land management practices, and prior land use ( [[#Calvin--2014c|Calvin et al. 2014c]] ; [[#Wise--2015|Wise et al. 2015]] ; [[#IPCC--2019a|IPCC 2019a]] ; [[#Smith--2019|Smith et al. 2019]] , 2020a; [[#Calvin--2021|Calvin et al. 2021]] ).

Pathways with very high biomass production for energy use typically include very high carbon prices in the energy system ( [[#Popp--2017|Popp et al. 2017]] ; [[#Rogelj--2018|Rogelj et al. 2018]] b), little or no land policy ( [[#Calvin--2014b|Calvin et al. 2014b]] ), a high discount rate ( [[#Emmerling--2019|Emmerling et al. 2019]] ), and limited non-BECCS CDR options (e.g., afforestation, DACCS) ( [[#Chen--2013|Chen and Tavoni 2013]] ; [[#Calvin--2014b|Calvin et al. 2014b]] ; [[#Marcucci--2017|Marcucci et al. 2017]] ; [[#Realmonte--2019|Realmonte et al. 2019]] ; [[#Fuhrman--2020|Fuhrman et al. 2020]] ). Higher levels of bioenergy consumption are likely to involve trade-offs with mitigation in other sectors, notably in construction (i.e., wood for material and structural products) and AFOLU (carbon stocks and future carbon sequestration), as well as trade-offs with sustainability ( [[#3.7|Section 3.7]] ) and feasibility concerns ( [[#3.8|Section 3.8]] ). Not all of these trade-offs are fully represented in all IAMs. Based on sectoral studies, the technical potential for bioenergy, when constraints for food security and environmental considerations are included, are 5–50 EJ yr –1 and 50–250 EJ yr –1 in 2050 for residues and dedicated biomass production systems, respectively (Chapter 7). Bioenergy deployment in IAMs is within the range of these potentials, with between 75 and 248 EJ yr –1 in 2050 in pathways that limit warming to 1.5°C with no or limited overshoot. Finally, IAMs do not include all potential feedstock and management practices, and have limited representation of institutions, governance, and local context ( [[#Brown--2019|Brown et al. 2019]] ; [[#Butnar--2020|Butnar et al. 2020]] ; [[#Calvin--2021|Calvin et al. 2021]] ).

The inclusion of CDR options, like BECCS, can affect the timing of emissions mitigation in IAM scenarios, that is, delays in mitigations actions are compensated by net negative emissions in the second half of the century. However, studies with limited net negative emissions in the long term require very rapid declines in emissions in the near term ( [[#van%20Vuuren--2017|van Vuuren et al. 2017]] ). Especially in forest-based systems, increased harvesting of forests can perturb the carbon balance of forestry systems, increasing emissions for some period; the duration of this period of increased emissions, preceding net emissions reductions, can be very variable ( [[#Mitchell--2012|Mitchell et al. 2012]] ; [[#Lamers--2013|Lamers and Junginger 2013]] ; [[#Röder--2019|Röder et al. 2019]] ; [[#Hanssen--2020|Hanssen et al. 2020]] ; [[#Cowie--2021|Cowie et al. 2021]] ). However, the factors contributing to differences in recovery time are known ( [[#Mitchell--2012|Mitchell et al. 2012]] ; [[#Zanchi--2012|Zanchi et al. 2012]] ; [[#Lamers--2013|Lamers and Junginger 2013]] ; [[#Laganière--2017|Laganière et al. 2017]] ; [[#Röder--2019|Röder et al. 2019]] ). Some studies that consider market-mediated effects find that an increased demand for biomass from forests can provide incentives to maintain existing forests and potentially to expand forest areas, providing additional carbon sequestration as well as additional biomass ( [[#Dwivedi--2014|Dwivedi et al. 2014]] ; [[#Kim--2018|Kim et al. 2018]] ; [[#Baker--2019|Baker et al. 2019]] ; [[#Favero--2020|Favero et al. 2020]] ). However, these responses are uncertain and likely to vary geographically.

<div id="3.4.2" class="h2-container"></div>

<span id="energy-supply"></span>