Editing IPCC:AR6/WGIII/SPM (section)

== E. Strengthening the Response ==

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'''E.1 There are mitigation options which are feasible [[#footnote-005|71]] to deploy at scale in the near term. Feasibility differs across sectors and regions, and according to capacities and the speed and scale of implementation. Barriers to feasibility would need to be reduced or removed, and enabling conditions [[#footnote-004|72]] strengthened to deploy mitigation options at scale. These barriers and enablers include geophysical, environmental-ecological, technological, and economic factors, and especially institutional and socio-cultural factors. Strengthened near-term action beyond the NDCs (announced prior to UNFCCC COP26) can reduce and/or avoid long-term feasibility challenges of global modelled pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot. ( high confidence ) Expand Links to chapters 3.8, 6.4, 8.5, 9.9, 10.8, 12.3, Figure TS.31, Annex II.IV.11'''
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'''E.1.1''' Several mitigation options, notably solar energy, wind energy, electrification of urban systems, urban green infrastructure, energy efficiency, demand-side management, improved forest- and crop/grassland management, and reduced food waste and loss, are technically viable, are becoming increasingly cost effective, and are generally supported by the public. This enables deployment in many regions ( ''high confidence'' ). While many mitigation options have environmental co-benefits, including improved air quality and reducing toxic waste, many also have adverse environmental impacts, such as reduced biodiversity, when applied at very large scale, for example very large scale bioenergy or large scale use of battery storage, that would have to be managed ( ''medium confidence'' ). Almost all mitigation options face institutional barriers that need to be addressed to enable their application at scale ( ''medium confidence'' ). {6.4, Figure 6.19, 7.4, 8.5, Figure 8.19, 9.9, Figure 9.20, 10.8, Figure 10.23, 12.3, Figure 12.4, Figure TS.31}

'''E.1.2''' The feasibility of mitigation options varies according to context and time. For example, the institutional capacity to support deployment varies across countries; the feasibility of options that involve large-scale land-use changes varies across regions; spatial planning has a higher potential at early stages of urban development; the potential of geothermal is site specific; and capacities, cultural and local conditions can either inhibit or enable demand-side responses. The deployment of solar and wind energy has been assessed to become increasingly feasible over time. The feasibility of some options can increase when combined or integrated, such as using land for both agriculture and centralised solar production. ( ''high confidence'' ) {6.4, 6.6, Supplementary Material Table 6.SM, 7.4, 8.5, Supplementary Material Table 8.SM.2, 9.9, Supplementary Material Table 9.SM.1, 10.8, Appendix 10.3, 12.3, Tables 12.SM.2.1 to 12.SM.2.6}

'''E.1.3''' Feasibility depends on the scale and speed of implementation. Most options face barriers when they are implemented rapidly at a large scale, but the scale at which barriers manifest themselves varies. Strengthened and coordinated near-term actions in cost-effective modelled global pathways that limit warming to 2°C (&gt;67%) or lower, reduce the overall risks to the feasibility of the system transitions, compared to modelled pathways with relatively delayed or uncoordinated action. [[#footnote-003|73]] ( ''high confidence'' ) {3.8, 6.4, 10.8, 12.3}

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'''E.2 In all countries, mitigation efforts embedded within the wider development context can increase the pace, depth and breadth of emissions reductions ( medium confidence ). Policies that shift development pathways towards sustainability can broaden the portfolio of available mitigation responses, and enable the pursuit of synergies with development objectives ( medium confidence ). Actions can be taken now to shift development pathways and accelerate mitigation and transitions across systems ( high confidence ) Expand Links to chapters 4.3, 4.4, Cross-Chapter Box 5 in Chapter 4, 5.2, 5.4, 13.9, 14.5, 15.6, 16.3, 16.4, 16.5'''
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'''E.2.1''' Current development pathways may create behavioural, spatial, economic and social barriers to accelerated mitigation at all scales ( ''high confidence'' ). Choices made by policymakers, citizens, the private sector and other stakeholders influence societies’ development pathways ( ''high confidence'' ). Actions that steer, for example, energy and land systems transitions, economy-wide structural change, and behaviour change, can shift development pathways towards sustainability [[#footnote-002|74]] ( ''medium confidence'' ). {4.3, Cross-Chapter Box 5 in Chapter 4, 5.4, 13.9}

'''E.2.2''' Combining mitigation with policies to shift development pathways, such as broader sectoral policies, policies that induce lifestyle or behaviour changes, financial regulation, or macroeconomic policies can overcome barriers and open up a broader range of mitigation options ( ''high confidence'' ). It can also facilitate the combination of mitigation and other development goals ( ''high confidence'' ). For example, measures promoting walkable urban areas combined with electrification and renewable energy can create health co-benefits from cleaner air and benefits from enhanced mobility ( ''high confidence'' ). Coordinated housing policies that broaden relocation options can make mitigation measures in transport more effective ( ''medium confidence'' ). {3.2, 4.3, 4.4, Cross-Chapter Box 5 in Chapter 4, 5.3, 8.2, 8.4}

'''E.2.3''' Institutional and regulatory capacity, innovation, finance, improved governance and collaboration across scales, and multi-objective policies enable enhanced mitigation and shifts in development pathways. Such interventions can be mutually reinforcing and establish positive feedback mechanisms, resulting in accelerated mitigation. ( ''high confidence'' ) {4.4, 5.4, Figure 5.14, 5.6, 9.9, 13.9, 14.5, 15.6, 16.3, 16.4, 16.5, Cross-Chapter Box 12 in Chapter 16}

'''E.2.4''' Enhanced action on all the above enabling conditions can be taken now ( ''high confidence'' ). In some situations, such as with innovation in technology at an early stage of development and some changes in behaviour towards low emissions, because the enabling conditions may take time to be established, action in the near term can yield accelerated mitigation in the mid-term ( ''medium confidence'' ). In other situations, the enabling conditions can be put in place and yield results in a relatively short time frame, for example the provision of energy related information, advice and feedback to promote energy saving behaviour ( ''high confidence'' ). {4.4, 5.4, Figure 5.14, 5.6, 6.7, 9.9, 13.9, 14.5, 15.6, 16.3, 16.4, 16.5, Cross-Chapter Box 12 in Chapter 16}

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'''E.3 Climate governance, acting through laws, strategies and institutions, based on national circumstances, supports mitigation by providing frameworks through which diverse actors interact, and a basis for policy development and implementation ( medium confidence ). Climate governance is most effective when it integrates across multiple policy domains, helps realise synergies and minimise trade-offs, and connects national and sub-national policymaking levels ( high confidence ). Effective and equitable climate governance builds on engagement with civil society actors, political actors, businesses, youth, labour, media, Indigenous Peoples and local communities ( medium confidence ). Expand Links to chapters 5.4, 5.6, 8.5, 9.9, 13.2, 13.7, 13.9'''
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'''E.3.1''' Climate governance enables mitigation by providing an overall direction, setting targets, mainstreaming climate action across policy domains, enhancing regulatory certainty, creating specialised organisations and creating the context to mobilise finance ( ''medium confidence'' ). These functions can be promoted by climate-relevant laws, which are growing in number, or climate strategies, among others, based on national and sub-national context ( ''medium confidence'' ). Framework laws set an overarching legal basis, either operating through a target and implementation approach, or a sectoral mainstreaming approach, or both, depending on national circumstance ( ''medium confidence'' ). Direct national and sub-national laws that explicitly target mitigation and indirect laws that impact emissions through mitigation-related policy domains have both been shown to be relevant to mitigation outcomes ( ''medium confidence'' ). {13.2}

'''E.3.2''' Effective national climate institutions address coordination across sectors, scales and actors, build consensus for action among diverse interests, and inform strategy setting ( ''medium confidence'' ). These functions are often accomplished through independent national expert bodies, and high-level coordinating bodies that transcend departmental mandates. Complementary sub-national institutions tailor mitigation actions to local context and enable experimentation but can be limited by inequities and resource and capacity constraints ( ''high confidence'' ). Effective governance requires adequate institutional capacity at all levels ( ''high confidence'' ). {4.4, 8.5, 9.9, 11.3, 11.5, 11.6, 13.2, 13.5, 13.7, 13.9}

'''E.3.3''' The extent to which civil society actors, political actors, businesses, youth, labour, media, Indigenous Peoples, and local communities are engaged influences political support for climate change mitigation and eventual policy outcomes. Structural factors of national circumstances and capabilities (e.g., economic and natural endowments, political systems and cultural factors and gender considerations) affect the breadth and depth of climate governance. Mitigation options that align with prevalent ideas, values and beliefs are more easily adopted and implemented. Climate-related litigation, for example by governments, private sector, civil society and individuals, is growing - with a large number of cases in some developed countries, and with a much smaller number in some developing countries - and in some cases, has influenced the outcome and ambition of climate governance. ( ''medium confidence'' ) {5.2, 5.4, 5.5, 5.6, 9.9, 13.3, 13.4}

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'''E.4 Many regulatory and economic instruments have already been deployed successfully. Instrument design can help address equity and other objectives. These instruments could support deep emissions reductions and stimulate innovation if scaled up and applied more widely ( high confidence ). Policy packages that enable innovation and build capacity are better able to support a shift towards equitable low-emission futures than are individual policies ( high confidence ). Economy-wide packages, consistent with national circumstances, can meet short-term economic goals while reducing emissions and shifting development pathways towards sustainability ( medium confidence ). Expand Links to chapters Cross-Chapter Box 5 in Chapter 4, 13.6, 13.7, 13.9, 16.3, 16.4, 16.6'''
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'''E.4.1''' A wide range of regulatory instruments at the sectoral level have proven effective in reducing emissions. These instruments, and broad-based approaches including relevant economic instruments, [[#footnote-001|75]] are complementary ( ''high confidence'' ). Regulatory instruments that are designed to be implemented with flexibility mechanisms can reduce costs ( ''medium confidence'' ). Scaling up and enhancing the use of regulatory instruments, consistent with national circumstances, could improve mitigation outcomes in sectoral applications, including but not limited to renewable energy, land use and zoning, building codes, vehicle and energy efficiency, fuel standards, and low-emissions industrial processes and materials ( ''high confidence'' ). {6.7, 7.6, 8.4, 9.9, 10.4, 11.5, 11.6, 13.6}

'''E.4.2''' Economic instruments have been effective in reducing emissions, complemented by regulatory instruments mainly at the national and also sub-national and regional level ( ''high confidence'' ). Where implemented, carbon pricing instruments have incentivised low-cost emissions reduction measures, but have been less effective, on their own and at prevailing prices during the assessment period, in promoting the higher-cost measures necessary for further reductions ( ''medium confidence'' ). Equity and distributional impacts of such carbon pricing instruments can be addressed by using revenue from carbon taxes or emissions trading to support low-income households, among other approaches ( ''high confidence'' ). Practical experience has informed instrument design and helped to improve predictability, environmental effectiveness, economic efficiency, distributional goals and social acceptance ( ''high confidence'' ). Removing fossil fuel subsidies would reduce emissions, improve public revenue and macroeconomic performance, and yield other environmental and sustainable development benefits; subsidy removal may have adverse distributional impacts especially on the most economically vulnerable groups which, in some cases can be mitigated by measures such as redistributing revenue saved, all of which depend on national circumstances ( ''high confidence'' ); fossil fuel subsidy removal is projected by various studies to reduce global CO 2 emissions by 1–4%, and GHG emissions by up to 10% by 2030, varying across regions ( ''medium confidence'' ). {6.3, 13.6}

'''E.4.3''' Low-emission technological innovation is strengthened through the combination of dedicated technology-push policies and investments (e.g., for scientific training, R&amp;D, demonstration), with tailored demand-pull policies (e.g., standards, feed-in tariffs, taxes), which create incentives and market opportunities. Developing countries’ abilities to deploy low-emission technologies, seize socio-economic benefits and manage trade-offs would be enhanced with increased financial resources and capacity for innovation which are currently concentrated in developed countries, alongside technology transfer. ( ''high confidence'' ) {16.2, 16.3, 16.4, 16.5}

'''E.4.4''' Effective policy packages would be comprehensive in coverage, harnessed to a clear vision for change, balanced across objectives, aligned with specific technology and system needs, consistent in terms of design and tailored to national circumstances. They are better able to realise synergies and avoid trade-offs across climate and development objectives. Examples include: emissions reductions from buildings through a mix of efficiency targets, building codes, appliance performance standards, information provision, carbon pricing, finance and technical assistance; and industrial GHG emissions reductions through innovation support, market creation and capacity building. ( ''high confidence'' ) {4.4, 6.7, 9.9, 11.6, 13.7, 13.9, 16.3, 16.4}

'''E.4.5''' Economy-wide packages that support mitigation and avoid negative environmental outcomes include: long-term public spending commitments; pricing reform; and investment in education and training, natural capital, R&amp;D and infrastructure ( ''high confidence'' ). They can meet short-term economic goals while reducing emissions and shifting development pathways towards sustainability ( ''medium confidence'' ). Infrastructure investments can be designed to promote low-emissions futures that meet development needs ( ''medium confidence'' ). {Cross-Chapter Box 5 in Chapter 4, 5.4, 5.6, 8.5, 13.6, 13.9, 16.3, 16.5, 16.6}

'''E.4.6''' National policies to support technology development and diffusion, and participation in international markets for emission reduction, can bring positive spillover effects for other countries ( ''medium confidence'' ), although reduced demand for fossil fuels could result in costs to exporting countries ( ''high confidence'' ). There is no consistent evidence that current emission trading systems have led to significant emissions leakage, which can be attributed to design features aimed at minimising competitiveness effects, among other reasons ( ''medium confidence'' ). {13.6, 13.7, 13.8, 16.2, 16.3, 16.4}

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'''E.5 Tracked financial flows fall short of the levels needed to achieve mitigation goals across all sectors and regions. The challenge of closing gaps is largest in developing countries as a whole. Scaling up mitigation financial flows can be supported by clear policy choices and signals from governments and the international community ( high confidence ). Accelerated international financial cooperation is a critical enabler of low-GHG and just transitions, and can address inequities in access to finance and the costs of, and vulnerability to, the impacts of climate change ( high confidence ) Expand Links to chapters 15.2, 15.3, 15.4, 15.5, 15.6'''
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'''E.5.1''' Average annual modelled investment requirements for 2020 to 2030 in scenarios that limit warming to 2°C or 1.5°C are a factor of three to six greater than current levels, and total mitigation investments (public, private, domestic and international) would need to increase across all sectors and regions ( ''medium confidence'' ). Mitigation investment gaps are wide for all sectors, and widest for the AFOLU sector in relative terms and for developing countries [[#footnote-000|76]] ( ''high'' ''confidence'' ) ''.'' Financing and investment requirements for adaptation, reduction of losses and damages, general infrastructure, regulatory environment and capacity building, and climate-responsive social protection further exacerbate the magnitude of the challenges for developing countries to attract financing ( ''high confidence'' ). {3.2, 14.4, 15.1, 15.2, 15.3, 15.4, 15.5}

'''E.5.2''' There is sufficient global capital and liquidity to close global investment gaps, given the size of the global financial system, but there are barriers to redirect capital to climate action both within and outside the global financial sector, and in the macroeconomic headwinds facing developing regions. Barriers to the deployment of commercial finance from within the financial sector as well as macroeconomic considerations include: inadequate assessment of climate-related risks and investment opportunities; regional mismatch between available capital and investment needs; home bias factors; country indebtedness levels; economic vulnerability; and limited institutional capacities ( ''high confidence'' ). Challenges from outside the financial sector include: limited local capital markets; unattractive risk-return profiles, in particular due to missing or weak regulatory environments consistent with ambition levels; limited institutional capacity to ensure safeguards; standardisation, aggregation, scalability and replicability of investment opportunities and financing models; and, a pipeline ready for commercial investments. ( ''high confidence'' ) {15.2, 15.3, 15.5, 15.6}

'''E.5.3''' Accelerated financial support for developing countries from developed countries and other sources is a critical enabler to enhance mitigation action and address inequities in access to finance, including its costs, terms and conditions, and economic vulnerability to climate change for developing countries ( ''high confidence'' ). Scaled-up public grants for mitigation and adaptation funding for vulnerable regions, especially in Sub-Saharan Africa, would be cost-effective and have high social returns in terms of access to basic energy ( ''high confidence'' ). Options for scaling up mitigation in developing regions include: increased levels of public finance and publicly mobilised private finance flows from developed to developing countries in the context of the USD100 billion-a-year goal; increase the use of public guarantees to reduce risks and leverage private flows at lower cost; local capital markets development; and building greater trust in international cooperation processes ( ''high confidence'' ) ''.'' A coordinated effort to make the post-pandemic recovery sustainable and increased flows of financing over the next decade can accelerate climate action, including in developing regions and countries facing high debt costs, debt distress and macroeconomic uncertainty ( ''high confidence'' ). {15.2, 15.3, 15.4, 15.5, 15.6, Box 15.6}

'''E.5.4''' Clear signalling by governments and the international community, including a stronger alignment of public sector finance and policy, and higher levels of public sector climate finance, reduces uncertainty and transition risks for the private sector. Depending on national contexts, investors and financial intermediaries, central banks, and financial regulators can support climate action and can shift the systemic underpricing of climate-related risk by increasing awareness, transparency and consideration of climate-related risk, and investment opportunities. Financial flows can also be aligned with funding needs through: greater support for technology development; a continued role for multilateral and national climate funds and development banks; lowering financing costs for underserved groups through entities such as green banks existing in some countries, funds and risk-sharing mechanisms; economic instruments which consider economic and social equity and distributional impacts; gender-responsive and women-empowerment programmes as well as enhanced access to finance for local communities and Indigenous Peoples and small land owners; and greater public-private cooperation. ( ''high confidence'' ) {15.2, 15.5, 15.6}

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'''E.6 International cooperation is a critical enabler for achieving ambitious climate change mitigation goals . The UNFCCC, Kyoto Protocol, and Paris Agreement are supporting rising levels of national ambition and encouraging development and implementation of climate policies, although gaps remain. Partnerships, agreements, institutions and initiatives operating at the sub-global and sectoral levels and engaging multiple actors are emerging, with mixed levels of effectiveness. ( high confidence ) Expand Links to chapters 8.5, 14.2, 14.3, 14.5, 14.6, 15.6, 16.5'''
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'''E.6.1''' Internationally agreed processes and goals, such as those in the UNFCCC, Kyoto Protocol, and Paris Agreement – including transparency requirements for national reporting on emissions, actions and support, and tracking progress towards the achievement of Nationally Determined Contributions – are enhancing international cooperation, national ambition and policy development. International financial, technology and capacity building support to developing countries will enable greater implementation and encourage ambitious Nationally Determined Contributions over time. ( ''medium confidence'' ) {14.3}

'''E.6.2''' International cooperation on technology development and transfer accompanied by capacity building, knowledge sharing, and technical and financial support can accelerate the global diffusion of mitigation technologies, practices and policies at national and sub-national levels, and align these with other development objectives ( ''high confidence'' ). Challenges in and opportunities to enhance innovation cooperation exist, including in the implementation of elements of the UNFCCC and the Paris Agreement as per the literature assessed, such as in relation to technology development and transfer, and finance ( ''high confidence'' ). International cooperation on innovation works best when tailored to specific institutional and capability contexts, when it benefits local value chains, when partners collaborate equitably and on voluntary and mutually agreed terms, when all relevant voices are heard, and when capacity building is an integral part of the effort ( ''medium confidence'' ). Support to strengthen technological innovation systems and innovation capabilities, including through financial support in developing countries would enhance engagement in and improve international cooperation on innovation ( ''high confidence'' ). {4.4, 14.2, 14.4, 16.3, 16.5, 16.6}

'''E.6.3''' Transnational partnerships can stimulate policy development, low-emissions technology diffusion and emission reductions by linking sub-national and other actors, including cities, regions, non-governmental organisations and private sector entities, and by enhancing interactions between state and non-state actors. While this potential of transnational partnerships is evident, uncertainties remain over their costs, feasibility, and effectiveness. Transnational networks of city governments are leading to enhanced ambition and policy development and a growing exchange of experience and best practices ( ''medium confidence'' ). {8.5, 11.6, 14.5, 16.5, Cross-Chapter Box 12 in Chapter 16}

'''E.6.4''' International environmental and sectoral agreements, institutions, and initiatives are helping, and in some cases may help, to stimulate low-GHG emissions investment and reduce emissions. Agreements addressing ozone depletion and transboundary air pollution are contributing to mitigation, and in other areas, such as atmospheric emissions of mercury, may contribute to mitigation ( ''high confidence'' ). Trade rules have the potential to stimulate international adoption of mitigation technologies and policies, but may also limit countries’ ability to adopt trade-related climate policies ( ''medium confidence'' ). Current sectoral levels of ambition vary, with emission reduction aspirations in international aviation and shipping lower than in many other sectors ( ''medium confidence'' ). {14.5, 14.6}

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[[#footnote-075-backlink|1]] The Report covers literature accepted for publication by 11 October 2021.

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[[#footnote-074-backlink|2]] Each finding is grounded in an evaluation of underlying evidence and agreement. A level of confidence is expressed using five qualifiers, typeset in italics: ''very low'' , ''low'' , ''medium'' , ''high'' and ''very high'' . The assessed likelihood of an outcome or a result is described as: ''virtually certain'' 99–100% probability; ''very likely'' 90–100%; ''likely'' 66–100%; ''more likely than not'' 50–100%; ''about as likely as not'' 33–66%; ''unlikely'' 0–33%; ''very unlikely'' 0–10%; ''exceptionally unlikely'' 0–1%. Additional terms may also be used when appropriate, consistent with the IPCC uncertainty guidance: https://www.ipcc.ch/site/assets/uploads/2018/05/uncertainty-guidance-note.pdf .

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[[#footnote-073-backlink|3]] The three Special Reports are: Global Warming of 1.5°C: an IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty (2018); Climate Change and Land: an IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems (2019); IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (2019).

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[[#footnote-072-backlink|4]] The term ‘temperature’ is used in reference to 'global surface temperatures' throughout this SPM as defined in footnote 8 of the AR6 WGI SPM (see note 14 of Table SPM.2). Emission pathways and associated temperature changes are calculated using various forms of models, as summarised in Box SPM.1 and Chapter 3, and discussed in Annex III.

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[[#footnote-071-backlink|5]] Namely: Economic Benefits from Avoided Climate Impacts along Long-Term Mitigation Pathways {Cross-Working Group Box 1 in Chapter 3} ; Urban: Cities and Climate Change {Cross-Working Group Box 2 in Chapter 8} ; and Mitigation and Adaptation via the Bioeconomy {Cross-Working Group Box 3 in Chapter 12} .

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[[#footnote-070-backlink|6]] Net GHG emissions in this report refer to releases of greenhouse gases from anthropogenic sources minus removals by anthropogenic sinks, for those species of gases that are reported under the common reporting format of the United Nations Framework Convention on Climate Change (UNFCCC): CO 2 from fossil fuel combustion and industrial processes (CO 2 -FFI); net CO 2 emissions from land use, land-use change and forestry (CO 2 -LULUCF); methane (CH 4 ); nitrous oxide (N 2 O); and fluorinated gases (F-gases) comprising hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF 6 ), as well as nitrogen trifluoride (NF 3 ). Different datasets for GHG emissions exist, with varying time horizons and coverage of sectors and gases, including some that go back to 1850. In this report, GHG emissions are assessed from 1990, and CO 2 sometimes also from 1850. Reasons for this include data availability and robustness, scope of the assessed literature, and the differing warming impacts of non-CO 2 gases over time.

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[[#footnote-069-backlink|7]] GHG emission metrics are used to express emissions of different greenhouse gases in a common unit. Aggregated GHG emissions in this report are stated in CO 2 -equivalent (CO 2 -eq) using the Global Warming Potential with a time horizon of 100 years (GWP100) with values based on the contribution of Working Group I to the AR6. The choice of metric depends on the purpose of the analysis, and all GHG emission metrics have limitations and uncertainties, given that they simplify the complexity of the physical climate system and its response to past and future GHG emissions. {Cross-Chapter Box 2 in Chapter 2, Supplementary Material 2.SM.3, Box TS.2; AR6 WGI &lt;a class='section-link' data-title='Agriculture, Forestry, and Other Land Uses (AFOLU)' href='/chapters/chapter-7'&gt;Chapter 7&lt;/a&gt; Supplementary Material}

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[[#footnote-068-backlink|8]] In this SPM, uncertainty in historic GHG emissions is reported using 90% uncertainty intervals unless stated otherwise. GHG emission levels are rounded to two significant digits; as a consequence, small differences in sums due to rounding may occur.

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[[#footnote-067-backlink|9]] Global databases make different choices about which emissions and removals occurring on land are considered anthropogenic. Currently, net CO 2 fluxes from land reported by global bookkeeping models used here are estimated to be about 5.5 GtCO 2 yr –1 higher than the aggregate global net emissions based on national GHG inventories. This difference, which has been considered in the literature, mainly reflects differences in how anthropogenic forest sinks and areas of managed land are defined. Other reasons for this difference, which are more difficult to quantify, can arise from the limited representation of land management in global models and varying levels of accuracy and completeness of estimated LULUCF fluxes in national GHG inventories. Neither method is inherently preferable. Even when the same methodological approach is applied, the large uncertainty of CO 2 -LULUCF emissions can lead to substantial revisions to estimated emissions. {Cross-Chapter Box 3 in Chapter 3, 7.2, SRCCL SPM A.3.3}

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[[#footnote-066-backlink|10]] For consistency with WGI, historical cumulative CO 2 emissions from 1850 to 2019 are reported using 68% confidence intervals.

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[[#footnote-065-backlink|11]] The carbon budget is the maximum amount of cumulative net global anthropogenic CO 2 emissions that would result in limiting global warming to a given level with a given likelihood, taking into account the effect of other anthropogenic climate forcers. This is referred to as the ‘total carbon budget’ when expressed starting from the pre-industrial period, and as the ‘remaining carbon budget’ when expressed from a recent specified date. The total carbon budgets reported here are the sum of historical emissions from 1850 to 2019 and the remaining carbon budgets from 2020 onwards, which extend until global net zero CO 2 emissions are reached. {Annex I: Glossary; WGI SPM}

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[[#footnote-064-backlink|12]] Uncertainties for total carbon budgets have not been assessed and could affect the specific calculated fractions.

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[[#footnote-063-backlink|13]] Sector definitions can be found in Annex II.9.1.

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[[#footnote-062-backlink|14]] Land overall constituted a net sink of –6.6 (±4.6) GtCO 2 yr –1 for the period 2010–2019, comprising a gross sink of –12.5 (±3.2) GtCO 2 yr –1 resulting from responses of all land to both anthropogenic environmental change and natural climate variability, and net anthropogenic CO 2 -LULUCF emissions +5.7 (±4.0) GtCO 2 yr –1 based on bookkeeping models. {Table 2.1, 7.2, Table 7.1}

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[[#footnote-061-backlink|15]] This estimate is based on consumption-based accounting, including both direct emissions from within urban areas, and indirect emissions from outside urban areas related to the production of electricity, goods and services consumed in cities. These estimates include all CO 2 and CH 4 emission categories except for aviation and marine bunker fuels, land-use change, forestry and agriculture. {8.1, Annex I: Glossary}

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[[#footnote-060-backlink|16]] See Box SPM.1 for the categorisation of modelled long-term emission scenarios based on projected temperature outcomes and associated probabilities adopted in this report.

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[[#footnote-059-backlink|17]] See Annex II, Part 1 for regional groupings adopted in this report.

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[[#footnote-058-backlink|18]] In 2019, LDCs are estimated to have emitted 3.3% of global GHG emissions, and SIDS are estimated to have emitted 0.6% of global GHG emissions, excluding CO 2 -LULUCF. These country groupings cut across geographic regions and are not depicted separately in Figure SPM.2. {Figure 2.10}

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[[#footnote-057-backlink|19]] In this report, access to modern energy services is defined as access to clean, reliable and affordable energy services for cooking and heating, lighting, communications, and productive uses. {Annex I: Glossary}

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[[#footnote-056-backlink|20]] In this report, decent living standards are defined as a set of minimum material requirements essential for achieving basic human well-being, including nutrition, shelter, basic living conditions, clothing, health care, education, and mobility. {5.1}

<div id="footnote-055" class="_idFootnote"></div>

[[#footnote-055-backlink|21]] Consumption-based emissions refer to emissions released to the atmosphere to generate the goods and services consumed by a certain entity (e.g., a person, firm, country, or region). The bottom 50% of emitters spend less than USD3 PPP (purchasing power parity) per capita per day. The top 10% of emitters (an open-ended category) spend more than USD23 PPP per capita per day. The wide range of estimates for the contribution of the top 10% results from the wide range of spending in this category and differing methods in the assessed literature. {2.6, Annex I: Glossary}

<div id="footnote-054" class="_idFootnote"></div>

[[#footnote-054-backlink|22]] Estimates of financial flows (comprising both private and public, domestic and international flows) are based on a single report which assembles data from multiple sources and which has applied various changes to their methodology over the past years. Such data can suggest broad trends but is subject to uncertainties.

<div id="footnote-053" class="_idFootnote"></div>

[[#footnote-053-backlink|23]] NDCs announced prior to COP26 refer to the most recent Nationally Determined Contributions submitted to the UNFCCC up to the literature cut-off date of this report, 11 October 2021, and revised NDCs announced by China, Japan and the Republic of Korea prior to October 2021 but only submitted thereafter. 25 NDC updates were submitted between 12 October 2021 and the start of COP26.

<div id="footnote-052" class="_idFootnote"></div>

[[#footnote-052-backlink|24]] This implies that mitigation after 2030 can no longer establish a pathway with less than 67% probability to exceed 1.5°C during the 21st century, a defining feature of the class of pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot assessed in this report (category C1 in Table SPM.2). These pathways limit warming to 1.6°C or lower throughout the 21st century with a 50% likelihood.

<div id="footnote-051" class="_idFootnote"></div>

[[#footnote-051-backlink|25]] The policy cut-off date in studies used to project GHG emissions of ‘policies implemented by the end of 2020’ varies between July 2019 and November 2020. {Table 4.2}

<div id="footnote-050" class="_idFootnote"></div>

[[#footnote-050-backlink|26]] Immediate action in modelled global pathways refers to the adoption between 2020 and at latest before 2025 of climate policies intended to limit global warming to a given level. Modelled pathways that limit warming to 2°C (&gt;67%) based on immediate action are summarised in category C3a in Table SPM.2. All assessed modelled global pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot assume immediate action as defined here (Category C1 in Table SPM.2).

<div id="footnote-049" class="_idFootnote"></div>

[[#footnote-049-backlink|27]] In this report, ‘unconditional’ elements of NDCs refer to mitigation efforts put forward without any conditions. ‘Conditional’ elements refer to mitigation efforts that are contingent on international cooperation, for example bilateral and multilateral agreements, financing or monetary and/or technological transfers. This terminology is used in the literature and the UNFCCC’s NDC Synthesis Reports, not by the Paris Agreement. {4.2.1, 14.3.2}

<div id="footnote-048" class="_idFootnote"></div>

[[#footnote-048-backlink|28]] Two types of gaps are assessed: the implementation gap is calculated as the difference between the median of global emissions in 2030 implied by policies implemented by the end of 2020 and those implied by NDCs announced prior to COP26. The emissions gap is calculated as the difference between GHG emissions implied by the NDCs (minimum/maximum emissions in 2030) and the median of global GHG emissions in modelled pathways limiting warming to specific levels based on immediate action and with stated likelihoods as indicated (Table SPM.2).

<div id="footnote-047" class="_idFootnote"></div>

[[#footnote-047-backlink|29]] Original NDCs refer to those submitted to the UNFCCC in 2015 and 2016. Unconditional elements of NDCs announced prior to COP26 imply global GHG emissions in 2030 that are 3.8 [3.0–5.3] GtCO 2 -eq yr –1 lower than those from the original NDCs, and 4.5 [2.7–6.3] GtCO 2 -eq yr –1 lower when conditional elements of NDCs are included. NDC updates at or after COP26 could further change the implied emissions.

<div id="footnote-046" class="_idFootnote"></div>

[[#footnote-046-backlink|30]] Median and ''very likely'' range [5th to 95th percentile].

<div id="footnote-045" class="_idFootnote"></div>

[[#footnote-045-backlink|31]] Returning to below 1.5°C in 2100 from GHG emissions levels in 2030 associated with the implementation of NDCs is infeasible for some models due to model-specific constraints on the deployment of mitigation technologies and the availability of net negative CO 2 emissions.

<div id="footnote-044" class="_idFootnote"></div>

[[#footnote-044-backlink|32]] See Box SPM.1 for a description of the approach to project global warming outcomes of modelled pathways and its consistency with the climate assessment in AR6 WGI.

<div id="footnote-043" class="_idFootnote"></div>

[[#footnote-043-backlink|33]] Historical operating patterns are described by load factors and lifetimes of fossil fuel installations as observed in the past (average and range).

<div id="footnote-042" class="_idFootnote"></div>

[[#footnote-042-backlink|34]] Abatement here refers to human interventions that reduce the amount of greenhouse gases that are released from fossil fuel infrastructure to the atmosphere.

<div id="footnote-041" class="_idFootnote"></div>

[[#footnote-041-backlink|35]] Total cumulative CO 2 emissions up to the time of global net zero CO 2 emissions are similar but not identical to the remaining carbon budget for a given temperature limit assessed by Working Group I. This is because the modelled emission scenarios assessed by Working Group III cover a range of temperature levels up to a specific limit, and exhibit a variety of reductions in non-CO 2 emissions that also contribute to overall warming. {Box 3.4}

<div id="footnote-040" class="_idFootnote"></div>

[[#footnote-040-backlink|36]] In this context, capture rates of new installations with CCS are assumed to be 90–95%+ {11.3.5} . Capture rates for retrofit installations can be comparable, if plants are specifically designed for CCS retrofits {11.3.6} .

<div id="footnote-039" class="_idFootnote"></div>

[[#footnote-039-backlink|37]] All reported warming levels are relative to the period 1850–1900. If not otherwise specified, ‘pathways’ always refer to pathways computed with a model. Immediate action in the pathways refers to the adoption of climate policies between 2020 and at latest 2025 intended to limit global warming at a given level.

<div id="footnote-038" class="_idFootnote"></div>

[[#footnote-038-backlink|38]] Long-term warming is calculated from all modelled pathways assuming mitigation efforts consistent with national policies that were implemented by the end of 2020 (scenarios that fall into policy category P1b of Chapter 3) and that pass through the 2030 GHG emissions ranges of such pathways assessed in Chapter 4 (see footnote 25). {3.2, Table 4.2}

<div id="footnote-037" class="_idFootnote"></div>

[[#footnote-037-backlink|39]] Warming estimates refer to the 50th and [5th–95th] percentile across the modelled pathways and the median temperature change estimate of the probabilistic WGI climate model emulators (see Table SPM.2 footnote a).

<div id="footnote-036" class="_idFootnote"></div>

[[#footnote-036-backlink|40]] In this report, emissions reductions are reported relative to 2019 modelled emission levels, while in SR1.5 emissions reductions were calculated relative to 2010. Between 2010 and 2019 global GHG and global CO 2 emissions have grown by 12% (6.5 GtCO 2 -eq) and 13% (5.0 GtCO 2 ) respectively. In global modelled pathways assessed in this report that limit warming to 1.5°C (&gt;50%) with no or limited overshoot, GHG emissions are projected to be reduced by 37% [28–57%] in 2030 relative to 2010. In the same type of pathways assessed in SR1.5, reported GHG emissions reductions in 2030 were 39–51% (interquartile range) relative to 2010. In absolute terms, the 2030 GHG emissions levels of pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot are higher in AR6 (31 [21–36] GtCO 2 -eq) than in SR1.5 (28 (26–31 interquartile range) GtCO 2 -eq). (Figure SPM.1, Table SPM.2) {3.3, SR1.5 Figure SPM.3b}

<div id="footnote-035" class="_idFootnote"></div>

[[#footnote-035-backlink|41]] Scenarios in this category limit peak warming to 2°C throughout the 21st century with close to, or more than, 90% likelihood.

<div id="footnote-034" class="_idFootnote"></div>

[[#footnote-034-backlink|42]] This category contains 91 scenarios with immediate action and 42 scenarios that are consistent with the NDCs until 2030.

<div id="footnote-033" class="_idFootnote"></div>

[[#footnote-033-backlink|43]] These numbers for CH 4 , N 2 O, and F-gases are rounded to the nearest 5% except numbers below 5%.

<div id="footnote-032" class="_idFootnote"></div>

[[#footnote-032-backlink|44]] In the literature, the terms ‘pathways’ and ‘scenarios’ are used interchangeably, with the former more frequently used in relation to climate goals. For this reason, this SPM uses mostly the term (emissions and mitigation) pathways. {Annex III.II.1.1}

<div id="footnote-031" class="_idFootnote"></div>

[[#footnote-031-backlink|45]] Key assumptions relate to technology development in agriculture and energy systems and socio-economic development, including demographic and economic projections. IPCC is neutral with regard to the assumptions underlying the scenarios in the literature assessed in this report, which do not cover all possible futures. Additional scenarios may be developed. The underlying population assumptions range from 8.5 to 9.7 billion in 2050 and 7.4 to 10.9 billion in 2100 (5–95th percentile) starting from 7.6 billion in 2019. The underlying assumptions on global GDP growth (ppp) range from 2.5 to 3.5% per year in the 2019–2050 period and 1.3 to 2.1% per year in the 2050–2100 (5–95th percentile). Many underlying assumptions are regionally differentiated. {1.5; 3.2; 3.3; Figure 3.9; Annex III.II.1.4; Annex III.II.3}

<div id="footnote-030" class="_idFootnote"></div>

[[#footnote-030-backlink|46]] The future scenario projections presented here are consistent with the total observed increase in global surface temperature between 1850–1900 and 1995–2014 as well as to 2011–2020 (with best estimates of 0.85°C and 1.09°C, respectively) assessed in WGI. The largest contributor to historical human-induced warming is CO 2 , with historical cumulative CO 2 emissions from 1850 to 2019 being 2400 ± 240 GtCO 2 . {WGI SPM A.1.2, WGI Table SPM.2, WGI Table 5.1, WGIII SPM Section B} .

<div id="footnote-029" class="_idFootnote"></div>

[[#footnote-029-backlink|47]] In case no explicit likelihood is provided, the reported warming levels are associated with a likelihood of &gt;50%.

<div id="footnote-028" class="_idFootnote"></div>

[[#footnote-028-backlink|48]] Scenarios in this category are found to have simultaneous likelihood to limit peak global warming to 2°C throughout the 21st century of close to and more than 90%.

<div id="footnote-027" class="_idFootnote"></div>

[[#footnote-027-backlink|49]] This involved improved methodologies to use climate emulators (MAGICC7 and FAIR v1.6), which were evaluated and calibrated to closely match the global warming response to emissions as assessed in AR6 WGI. It included harmonisation of global GHG emissions in 2015 in modelled scenarios (51–56 GtCO 2 -eq; 5th to 95th percentiles) with the corresponding emission value underlying the CMIP6 projected climate response assessed by WGI (54 GtCO 2 -eq), based on similar data sources of historical emissions that are updated over time. The assessment of past GHG emissions in [https://www.ipcc.ch/chapters/chapter-2 Chapter 2] of the report is based on a more recent dataset providing emissions of 57 [±6.3] GtCO 2 -eq in 2015 (B.1). Differences are well within the assessed uncertainty range, and arise mainly from differences in estimated CO 2 -LULUCF emissions, which are subject to large uncertainties, high annual variability and revisions over time. Projected rates of global emission reduction in mitigation scenarios are reported relative to modelled global emissions in 2019 rather than the global emissions reported in Chapter 2; this ensures internal consistency in assumptions about emission sources and activities, as well as consistency with temperature projections based on the physical climate science assessment by WG I. {Annex III.II.2.5}

<div id="footnote-026" class="_idFootnote"></div>

[[#footnote-026-backlink|50]] Cumulative net CO 2 emissions from the beginning of the year 2020 until the time of net zero CO 2 in assessed pathways are consistent with the remaining carbon budgets assessed by WGI, taking account of the ranges in the WGIII temperature categories and warming from non-CO 2 gases. {Box 3.4}

<div id="footnote-025" class="_idFootnote"></div>

[[#footnote-025-backlink|51]] All numbers here rounded to the closest 5%, except values below 5% (for F-gases).

<div id="footnote-024" class="_idFootnote"></div>

[[#footnote-024-backlink|52]] Most but not all models include the use of fossil fuels for feedstock with varying underlying standards.

<div id="footnote-023" class="_idFootnote"></div>

[[#footnote-023-backlink|53]] Aggregate levels of CDR deployment are higher than total net negative CO 2 emissions given that some of the deployed CDR is used to counterbalance remaining gross emissions. Total net negative CO 2 emissions in modelled pathways might not match the aggregated net negative CO 2 emissions attributed to individual CDR methods. Ranges refer to the 5–95th percentile across modelled pathways that include the specific CDR method. Cumulative levels of CDR from AFOLU cannot be quantified precisely given that: (i) some pathways assess CDR deployment relative to a baseline; and (ii) different models use different reporting methodologies that in some cases combine gross emissions and removals in AFOLU. Total CDR from AFOLU equals or exceeds the net negative emissions mentioned.

<div id="footnote-022" class="_idFootnote"></div>

[[#footnote-022-backlink|54]] In this context, ‘unabated fossil fuels’ refers to fossil fuels produced and used without interventions that substantially reduce the amount of GHG emitted throughout the life cycle; for example, capturing 90% or more CO 2 from power plants, or 50–80% of fugitive methane emissions from energy supply. {Box 6.5, 11.3}

<div id="footnote-021" class="_idFootnote"></div>

[[#footnote-021-backlink|55]] Primary metals refers to virgin metals produced from ore.

<div id="footnote-020" class="_idFootnote"></div>

[[#footnote-020-backlink|56]] These scenarios have been assessed by WGI to correspond to intermediate, high and very low GHG emissions.

<div id="footnote-019" class="_idFootnote"></div>

[[#footnote-019-backlink|57]] These examples are considered to be a subset of nature-based solutions or ecosystem-based approaches.

<div id="footnote-018" class="_idFootnote"></div>

[[#footnote-018-backlink|58]] Integration of renewable energy solutions refers to the integration of solutions such as solar photovoltaics, small wind turbines, solar thermal collectors, and biomass boilers.

<div id="footnote-017" class="_idFootnote"></div>

[[#footnote-017-backlink|59]] Sufficiency policies are a set of measures and daily practices that avoid demand for energy, materials, land and water while delivering human well-being for all within planetary boundaries.

<div id="footnote-016" class="_idFootnote"></div>

[[#footnote-016-backlink|60]] The global top-down estimates and sectoral bottom-up estimates described here do not include the substitution of emissions from fossil fuels and GHG-intensive materials. 8–14 GtCO 2 -eq yr –1 represents the mean of the AFOLU economic mitigation potential estimates from top-down estimates (lower bound of range) and global sectoral bottom-up estimates (upper bound of range). The full range from top-down estimates is 4.1–17.3 GtCO 2 -eq yr –1 using a ‘no policy’ baseline. The full range from global sectoral studies is 6.7–23.4 GtCO 2 -eq yr –1 using a variety of baselines. ( ''high confidence'' )

<div id="footnote-015" class="_idFootnote"></div>

[[#footnote-015-backlink|61]] ‘Sustainable healthy diets’ promote all dimensions of individuals’ health and well-being; have low environmental pressure and impact; are accessible, affordable, safe and equitable; and are culturally acceptable, as described in FAO and WHO. The related concept of ‘balanced diets’ refers to diets that feature plant-based foods, such as those based on coarse grains, legumes, fruits and vegetables, nuts and seeds, and animal-sourced food produced in resilient, sustainable and low-GHG emission systems, as described in SRCCL.

<div id="footnote-014" class="_idFootnote"></div>

[[#footnote-014-backlink|62]] ‘Choice architecture’ describes the presentation of choices to consumers, and the impact that presentation has on consumer decision-making.

<div id="footnote-013" class="_idFootnote"></div>

[[#footnote-013-backlink|63]] ‘Status consumption’ refers to the consumption of goods and services which publicly demonstrates social prestige.

<div id="footnote-012" class="_idFootnote"></div>

[[#footnote-012-backlink|64]] In modelled pathways that limit warming to 2°C (&gt;67%) or lower.

<div id="footnote-011" class="_idFootnote"></div>

[[#footnote-011-backlink|65]] The methodology underlying the assessment is described in the caption to Figure SPM.7.

<div id="footnote-010" class="_idFootnote"></div>

[[#footnote-010-backlink|66]] These estimates are based on 311 pathways that report effects of mitigation on GDP and that could be classified in temperature categories, but that do not account for damages from climate change nor adaptation costs and that mostly do not reflect the economic impacts of mitigation co-benefits and trade-offs. The ranges given are interquartile ranges. The macroeconomic implications quantified vary largely depending on technology assumptions, climate/emissions target formulation, model structure and assumptions, and the extent to which pre-existing inefficiencies are considered. Models that produced the pathways classified in temperature categories do not represent the full diversity of existing modelling paradigms, and there are in the literature models that find higher mitigation costs, or conversely lower mitigation costs and even gains. {1.7, 3.2, 3.6, Annex III.I.2, Annex III.I.9, Annex III.I.10 and Annex III.II.3}

<div id="footnote-009" class="_idFootnote"></div>

[[#footnote-009-backlink|67]] In modelled cost-effective pathways with a globally uniform carbon price, without international financial transfers or complementary policies, carbon intensive and energy exporting countries are projected to bear relatively higher mitigation costs because of a deeper transformation of their economies and changes in international energy markets. {3.6}

<div id="footnote-008" class="_idFootnote"></div>

[[#footnote-008-backlink|68]] The evidence is too limited to make a similar robust conclusion for limiting warming to 1.5°C.

<div id="footnote-007" class="_idFootnote"></div>

[[#footnote-007-backlink|69]] For nuclear energy, modelled costs for long-term storage of radioactive waste are included.

<div id="footnote-006" class="_idFootnote"></div>

[[#footnote-006-backlink|70]] Potential risks, knowledge gaps due to the relative immaturity of use of biochar as a soil amendment and unknown impacts of widespread application, and co-benefits of biochar are reviewed in [https://www.ipcc.ch/chapters/chapter-7#7.4.3.2 Section 7.4.3.2] .

<div id="footnote-005" class="_idFootnote"></div>

[[#footnote-005-backlink|71]] In this report, the term ‘feasibility’ refers to the potential for a mitigation or adaptation option to be implemented. Factors influencing feasibility are context-dependent and may change over time. Feasibility depends on geophysical, environmental-ecological, technological, economic, socio-cultural and institutional factors that enable or constrain the implementation of an option. The feasibility of options may change when different options are combined and increase when enabling conditions are strengthened.

<div id="footnote-004" class="_idFootnote"></div>

[[#footnote-004-backlink|72]] In this report, the term ‘enabling conditions’ refers to conditions that enhance the feasibility of adaptation and mitigation options. Enabling conditions include finance, technological innovation, strengthening policy instruments, institutional capacity, multi-level governance, and changes in human behaviour and lifestyles.

<div id="footnote-003" class="_idFootnote"></div>

[[#footnote-003-backlink|73]] The future feasibility challenges described in the modelled pathways may differ from the real-world feasibility experiences of the past.

<div id="footnote-002" class="_idFootnote"></div>

[[#footnote-002-backlink|74]] Sustainability may be interpreted differently in various contexts as societies pursue a variety of sustainable development objectives.

<div id="footnote-001" class="_idFootnote"></div>

[[#footnote-001-backlink|75]] Economic instruments are structured to provide a financial incentive to reduce emissions and include, among others, market- and price-based instruments.

<div id="footnote-000" class="_idFootnote"></div>

[[#footnote-000-backlink|76]] In modelled pathways, regional investments are projected to occur when and where they are most cost-effective to limit global warming. The model quantifications help to identify high-priority areas for cost-effective investments, but do not provide any indication on who would finance the regional investments.