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=== 4.5.2 Implementing Mitigation ===

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This section builds on the insights on mitigation options in Section 4.3, applies the assessment methodology along feasibility dimensions and indicators explained in Section 4.5.1, and synthesizes the assessment of the enabling conditions in Section 4.4.

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==== 4.5.2.1 Assessing mitigation options for limiting warming to 1.5˚C against feasibility dimensions ====

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An assessment of the degree to which examples of 1.5°C-relevant mitigation options face barriers to implementation, and on which contexts this depends, is summarized in Table 4.11. An explanation of the approach is given in Section 4.5.1 and in supplementary material 4.SM.4.1. Selected options were mapped onto system transitions and clustered through an iterative process of literature review, expert feedback, and responses to reviewer comments. The detailed assessment and the literature underpinning the assessment can be found in supplementary material 4.SM.4.2.

The feasibility framework in Cross-Chapter Box 3 in Chapter 1 highlights that the feasibility of mitigation and adaptation options depends on many factors. Many of those are captured in the indicators in Table 4.10, but many depend on the specific context in which an option features. This Special Report did not have the mandate, space or the literature base to undertake a regionally specific assessment. Hence the assessment is caveated as providing a broad indication of the likely global barriers, ignoring significant regional diversity. Regional and context-specific literature is also just emerging as is noted in the knowledge gaps section (Section 4.6). Nevertheless, in Table 4.11, an indicative attempt has been made to capture relevant contextual information. The ‘context’ column indicates which contextual factors may affect the feasibility of an option, including regional differences. For instance, solar irradiation in an area impacts the cost-effectiveness of solar photovoltaic energy, so solar irradiation is mentioned in this column.

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'''Table 4.11'''

Feasibility assessment of examples of 1.5°C-relevant mitigation options, with dark shading signifying the absence of barriers in the feasibility dimension, moderate<br />
shading indicating that, on average, the dimension does not have a positive or negative effect on the feasibility of the option, or the evidence is mixed, and faint<br />
shading the presence of potentially blocking barriers. No shading means that the literature found was not sufficient to make an assessment. Evidence and agreement<br />
assessment is undertaken at the option level. The context column on the far right indicates how the assessment might change if contextual factors were different. For<br />
the methodology and literature basis, see supplementary material 4.SM.4.1 and 4.SM.4.2.

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'''Abbreviations used:'''

Ec: Economic – Tec: Technological – Inst: Institutional – Soc: Socio-cultural – Env: Environmental/Ecological – Geo: Geophysical

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{| class="wikitable"
|-
! System
! Mitigation Option
! Evidence
! Agreement
! Ec
! Tec
! Inst
! Soc
! Env
! Geo
! Context
|-
| rowspan="6"| Energy System Transitions
| Wind energy (on-shore &amp; off-shore)
| Robust
| Medium
|
| Wind regime, economic status, space for wind farms, and the existence of a legal framework for independent power producers affect uptake; cost-effectiveness affected by incentive regime
|-
| Solar PV
| Robust
| High
|
| Cost-effectiveness affected by solar irradiation and incentive regime. Also enhanced by legal framework for independent power producers, which affects uptake
|-
| Bioenergy
| Robust
| Medium
|
| Depends on availability of biomass and land and the capability to manage sustainable land use. Distributional effects depend on the agrarian (or other) system used to produce feedstock
|-
| Electricity storage
| Robust
| High
|
| Batteries universal, but grid-flexible resources vary with area’s level of development
|-
| Power sector carbon dioxide capture and storage
| Robust
| High
|
| Varies with local CO <sub>2</sub> storage capacity, presence of legal framework, level of development and<br />
quality of public engagement
|-
| Nuclear energy
| Robust
| High
|
| Electricity market organization, legal framework, standardization &amp; know-how, country’s ‘democratic fabric’, institutional and technical capacity, and safety culture of public and private institutions
|-
| rowspan="4"| Land &amp; Ecosystem Transitions
| Reduced food wastage &amp; efficient food production
| Robust
| High
|
| Will depend on the combination of individual and institutional behaviour
|-
| Dietary shifts
| Medium
| High
|
| Depends on individual behaviour, education, cultural factors and institutional support
|-
| Sustainable intensification of agriculture
| Medium
| High
|
| Depends on development and deployment of new technologies
|-
| Ecosystems restoration
| Medium
| High
|
| Depends on location and institutional factors
|-
| rowspan="9"| Urban &amp; Infra structure System Transitions
| Land-use &amp; urban planning
| Robust
| Medium
|
| Varies with urban fabric, not geography or economy;<br />
requires capacitated local government and legitimate<br />
tenure system
|-
| Electric cars and buses
| Medium
| High
|
| Varies with degree of government intervention; requires capacity to retrofit “fuelling” stations
|-
| Sharing schemes
| Limited
| Medium
|
| Historic schemes universal, but new ones depend on ICT status; undermined by high crime and low levels of law enforcement
|-
| Public transport
| Robust
| Medium
|
| Depends on presence of existing ‘informal’ taxi systems, which may be more cost-effective and affordable than capital-intensive new build schemes, as well as (local) government capabilities
|-
| Non-motorized transport
| Robust
| High
|
| Viability rests on linkages with public transport, cultural factors, climate and geography
|-
| Aviation &amp; shipping
| Medium
|
| Varies with technology, governance and accountability
|-
| Smart grids
| Medium
|
| Varies with economic status and presence or quality of existing grid
|-
| Efficient appliances
| Medium
| High
|
| Adoption varies with economic status and policy<br />
framework
|-
| Low/zero-energy buildings
| Medium
| High
|
| Depends on size of existing building stock and growth of building stock
|-
| rowspan="4"| Industrial System Transitions
| Energy efficiency
| Robust
| High
|
| Potential and adoption depend on existing efficiency, energy prices and interest rates, as well as government incentives
|-
| Bio-based &amp; circularity
| Medium
|
| Faces barriers in terms of pressure on natural resources and biodiversity. Product substitution depends on market organization and government<br />
incentivization
|-
| Electrification &amp; hydrogen
| Medium
| High
|
| Depends on availability of large-scale, cheap, emission-free electricity (electrification, hydrogen) or CO <sub>2</sub> storage nearby (hydrogen). Manufacturers’ appetite to embrace disruptive innovations
|-
| Industrial carbon dioxide capture, utilization and storage
| Robust
| High
|
| High concentration of CO <sub>2</sub> in exhaust gas improve economic and technical feasibility of CCUS in industry. CO <sub>2</sub> storage or reuse possibilities
|-
| rowspan="5"| Carbon Dioxide Removal
| Bioenergy and carbon dioxide capture and storage
| Robust
| Medium
|
| Depends on biomass availability, CO <sub>2</sub> storage capacity, legal framework, economic status and social acceptance
|-
| Direct air carbon dioxide capture and storage
| Medium
|
| Depends on CO <sub>2</sub> -free energy, CO <sub>2</sub> storage capacity, legal framework, economic status and social acceptance
|-
| Afforestation &amp; reforestation
| Robust
| High
|
| Depends on location, mode of implementation, and economic and institutional factors
|-
| Soil carbon sequestration &amp; biochar
| Robust
| High
|
| Depends on location, soil properties, time span
|-
| Enhanced weathering
| Medium
| Low
|
| Depends on CO <sub>2</sub> -free energy, economic status and social acceptance
|}
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