Editing IPCC:AR6/SYR/Longer-Report (section)

=== 2.3 Current Mitigation and Adaptation Actions and Policies are not Sufficient ===

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'''At the time of the present assessment '''[[#footnote-069|88]]''' there are gaps between global ambitions and the sum of declared national ambitions. These are further compounded by gaps between declared national ambitions and current implementation for all aspects of climate action. For mitigation, global GHG emissions in 2030 implied by NDCs announced by October 2021 would make it '''''likely''''' that warming will exceed 1.5°C during the 21st century and would make it harder to limit warming below 2°C. '''[[#footnote-068|89]]''' Despite progress, adaptation gaps '''[[#footnote-067|90]]''' persist, with many initiatives prioritising short-term risk reduction, hindering transformational adaptation. Hard and soft limits to adaptation are being reached in some sectors and regions, while maladaptation is also increasing and disproportionately affecting vulnerable groups. Systemic barriers such as funding, knowledge, and practice gaps, including lack of climate literacy and data hinders adaptation progress. Insufficient financing, especially for adaptation, constraints climate action in particular in developing countries. ( '''''high confidence''''' )'''
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==== 2.3.1. The Gap Between Mitigation Policies, Pledges and Pathways that Limit Warming to 1.5°C or Below 2°C ====

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'''Global GHG emissions in 2030 associated with the implementation of NDCs announced prior to COP26''' '''[[#footnote-066|91]] would make it''' '''''likely''''' '''that warming will exceed 1. 5°C during the 21st century and would make it harder to limit warming below 2°C – if no additional commitments are made or actions taken (Figure 2.5, Table 2.2).''' A substantial ‘emissions gap’ exists as global GHG emissions in 2030 associated with the implementation of NDCs announced prior to COP26 would be similar to or only slightly below 2019 emission levels and higher than those associated with modelled mitigation pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot or to 2°C (&gt;67%), assuming immediate action, which implies deep, rapid, and sustained global GHG emission reductions this decade ( ''high confidence'' ). (Table 2.2, Table 3.1, 4.1). '''[[#footnote-065|92]]''' The magnitude of the emissions gap depends on the global warming level considered and whether only unconditional or also conditional elements of NDCs '''[[#footnote-064|93]]''' are considered ( ''high confidence'' ) (Table 2.2). Modelled pathways that are consistent with NDCs announced prior to COP26 until 2030 and assume no increase in ambition thereafter have higher emissions, leading to a median global warming of 2.8 [2.1 to 3.4]°C by 2100 ( ''medium confidence'' ). If the ‘emission gap’ is not reduced, global GHG emissions in 2030 consistent with NDCs announced prior to COP26 make it ''likely'' that warming will exceed 1.5°C during the 21st century, while limiting warming to 2°C (&gt;67%) would imply an unprecedented acceleration of mitigation efforts during 2030–2050 ( ''medium confidence'' ) (see Section 4.1, Cross-Section Box.2). { ''WGIII SPM B.6, WGIII SPM B.6.1, WGIII SPM B.6.3, WGIII SPM B.6.4, WGIII SPM C.1.1'' }

'''Policies implemented by the end of 2020 are projected to result in higher global GHG emissions in 2030 than those implied by NDCs, i ndicating an ‘implementation gap''' '''[[#footnote-063|94]] ’ (''' '''''high confidence)''''' '''''( Table 2.2, Figure 2.5).''''' Projected global emissions implied by policies implemented by the end of 2020 are 57 (52–60) GtCO 2 -eq in 2030 (Table 2.2). This points to an implementation gap compared with the NDCs of 4 to 7 GtCO 2 -eq in 2030 (Table 2.2); without a strengthening of policies, emissions are projected to rise, leading to a median global warming of 2.2°C to 3.5°C ( ''very likely range'' ) by 2100 ( ''medium confidence'' )(see [[#3.1.1|Section 3.1.1]] ). { ''WGIII SPM B.6.1, WGIII SPM C.1'' }

Projected cumulative future CO 2 emissions over the lifetime of existing fossil fuel infrastructure without additional abatement '''[[#footnote-062|95]]''' exceed the total cumulative net CO 2 emissions in pathways that limit warming to 1.5°C (&gt;50%) with no or limited overshoot. They are approximately equal to total cumulative net CO 2 emissions in pathways that limit warming to 2°C with a likelihood of 83% '''[[#footnote-061|96]]''' (see Figure 3.5). Limiting warming to 2°C (&gt;67%) or lower will result in stranded assets. About 80% of coal, 50% of gas, and 30% of oil reserves cannot be burned and emitted if warming is limited to 2°C. Significantly more reserves are expected to remain unburned if warming is limited to 1.5°C. ( ''high confidence'' ). { ''WGIII SPM B.7, WGIII Box 6.3'' }

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'''Table 2.2 Projected global emissions in 2030 associated with policies implemented by the end of 2020 and NDCs announced prior to COP26, and associated emissions gaps.''' Emissions projections for 2030 and gross differences in emissions are based on emissions of 52–56 GtCO 2 -eq yr–1 in 2019 as assumed in underlying model studies '''[[#footnote-060|97]]''' . ( ''medium confidence'' ) { ''WGIII Table SPM.1'' } ( ''Table 3.1, Cross-Section Box.2'' ).

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'''Figure 2.5 Global GHG emissions of modelled pathways (funnels in Panel a), and projected emission outcomes from near-term policy assessments for 2030 (Panel b). Panel a''' shows global GHG emissions over 2015-2050 for four types of assessed modelled global pathways:

* Trend from implemented policies: Pathways with projected near-term GHG emissions in line with po licies implemented until the end of 2020 and extended with comparable ambition levels beyond 2030 (29 scenarios across categories C5–C7, WGIII Table SPM.2).
* Limit to 2°C (&gt;67%) or return warming to 1.5°C (&gt;50%) after a high overshoot, NDCs until 2030: Pathways with GHG emissions until 2030 associated with the implementation of NDCs announced prior to COP26, followed by accelerated emissions reductions likely to limit warming to 2°C (C3b, WGIII Table SPM.2) or to return warming to 1.5°C with a probability of 50% or greater after high overshoot (subset of 42 scenarios from C2, WGIII Table SPM.2).
* Limit to 2°C (&gt;67%) with immediate action: Pathways that limit warming to 2°C (&gt;67%) with immediate action after 2020 (C3a, WGIII Table SPM.2).
* Limit to 1.5°C (&gt;50%) with no or limited overshoot: Pathways limiting warming to 1.5°C with no or limited overshoot (C1, WGIII Table SPM.2 C1).

All these pathways assume immediate action after 2020. Past GHG emissions for 2010-2015 used to project global warming outcomes of the modelled pathways are shown by a black line. '''Panel b''' shows a snapshot of the GHG emission ranges of the modelled pathways in 2030 and projected emissions outcomes from near-term policy assessments in 2030 from WGIII Chapter 4.2 (Tables 4.2 and 4.3; median and full range). GHG emissions are CO 2 -equivalent using GWP100 from AR6 WGI. { ''WGIII Figure SPM.4, WGIII 3.5, 4.2, Table 4.2, Table 4.3, Cross-Chapter Box 4 in Chapter 4'' } ( ''Table 3.1, Cross-Section Box.2'' )

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'''Cross-Section Box.1: Understanding Net Zero CO''' '''2''' and Net Zero GHG Emissions

'''Limiting human-caused global warming to a specific level requires limiting cumulative CO''' '''2''' emissions, reaching net zero or net negative CO '''2''' emissions, along with strong reductions in other GHG emissions (see 3.3.2). Future additional warming will depend on future emissions, with total warming dominated by past and future cumulative CO 2 emissions. { ''WGI SPM D.1.1, WGIFigure SPM.4; SR1.5 SPM A.2.2'' } .

'''Reaching net zero CO''' '''2''' emissions is different from reaching net zero GHG emissions. The timing of net zero for a basket of GHGs depends on the emissions metric, such as global warming potential over a 100-year period, chosen to convert non-CO 2 emissions into CO 2 -equivalent ( ''high confidence'' ). However, for a given emissions pathway, the physical climate response is independent of the metric chosen ( ''high confidence'' ). { ''WGI SPM D.1.8; WGIII Box TS.6, WGIII Cross-Chapter Box 2'' }

'''Achieving global net zero GHG emissions requires all remaining CO''' '''2''' and metric-weighted '''[[#footnote-059|98]] non-CO''' '''2''' GHG emissions to be counterbalanced by durably stored CO '''2''' removals ( '''''high confidence).''''' Some non-CO 2 emissions, such as CH 4 and N 2 O from agriculture, cannot be fully eliminated using existing and anticipated technical measures. { ''WGIII SPM C.2.4, WGIII SPM C.11.4, WGIII Cross-Chapter Box 3'' }

'''Global net zero CO''' '''2''' or GHG emissions can be achieved even if some sectors and regions are net emitters, provided that others reach net negative emissions (see Figure 4.1). The potential and cost of achieving net zero or even net negative emissions vary by sector and region. If and when net zero emissions for a given sector or region are reached depends on multiple factors, including the potential to reduce GHG emissions and undertake carbon dioxide removal, the associated costs, and the availability of policy mechanisms to balance emissions and removals between sectors and countries. ( ''high confidence'' ). { ''WGIII Box TS.6, WGIII Cross-Chapter Box 3'' }

'''The adoption and implementation of net zero emission targets by countries and regions also depend on equity and capacity considerations (''' '''''high confidence).''''' The formulation of net zero pathways by countries will benefit from clarity on scope, plans-of-action, and fairness. Achieving net zero emission targets relies on policies, institutions, and milestones against which to track progress. Least-cost global modelled pathways have been shown to distribute the mitigation effort unevenly, and the incorporation of equity principles could change the country-level timing of net zero ( ''high confidence'' ). The Paris Agreement also recognizes that peaking of emissions will occur later in developing countries than developed countries (Article 4.1). { ''WGIII Box TS.6, WGIII Cross-Chapter Box 3, WGIII 14.3'' }

More information on country-level net zero pledges is provided in [[#2.3.1|Section 2.3.1]] , on the timing of global net zero emissions in [[#3.3.2|Section 3.3.2]] , and on sectoral aspects of net zero in Section 4.1.

'''Many countries have signalled an intention to achieve net zero GHG or net zero CO''' '''2''' emissions by around mid-century (Cross-Section Box.1). More than 100 countries have either adopted, announced or are discussing net zero GHG or net zero CO 2 emissions commitments, covering more than two-thirds of global GHG emissions. A growing number of cities are setting climate targets, including net zero GHG targets. Many companies and institutions have also announced net zero emissions targets in recent years. The various net zero emission pledges differ across countries in terms of scope and specificity, and limited policies are to date in place to deliver on them. { ''WGIII SPM C.6.4, WGIII TS.4.1, WGIII Table TS.1, WGIII 13.9, WGIII 14.3, WGIII 14.5'' } .

'''All mitigation strategies face implementation challenges, including technology risks, scaling, and costs (''' '''''high confidence).''''' Almost all mitigation options also face institutional barriers that need to be addressed to enable their application at scale ( ''medium confidence'' ). 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'' ). 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 ( ''medium confidence'' ). 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 ( ''medium confidence'' ). { ''WGIII SPM C.3.6, WGIII SPM E.1.1, WGIII SPM E.2.1, WGIII SPM E.3.3'' }

'''The adoption of low-emission technologies lags in most developing countries, particularly least developed ones, due in part to weaker enabling conditions, including limited finance, technology development and transfer, and capacity (''' '''''medium confidence).''''' In many countries, especially those with limited institutional capacity, several adverse side-effects have been observed as a result of diffusion of low-emission technology, e.g., low-value employment, and dependency on foreign knowledge and suppliers ( ''medium confidence'' ). Low-emission innovation along with strengthened enabling conditions can reinforce development benefits, which can, in turn, create feedbacks towards greater public support for policy. ( ''medium confidence)'' . Persistent and region-specific barriers also continue to hamper the economic and political feasibility of deploying AFOLU mitigation options ( ''medium confidence'' ). Barriers to implementation of AFOLU mitigation include insufficient institutional and financial support, uncertainty over long-term additionality and trade-offs, weak governance, insecure land ownership, low incomes and the lack of access to alternative sources of income, and the risk of reversal ( ''high confidence'' ). { ''WGIII SPM B.4.2, WGIII SPM C.9.1, WGIII SPM C.9.3'' } .

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==== 2.3.2. Adaptation Gaps and Barriers ====

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'''Despite progress, adaptation gaps exist between current levels of adaptation and levels needed to respond to impacts and reduce climate risks (''' '''''high confidence)''''' '''.''' While progress in adaptation implementation is observed across all sectors and regions . ''very high confidence)'' , many adaptation initiatives prioritise immediate and near-term climate risk reduction, e.g., through hard flood protection, which reduces the opportunity for transformational adaptation '''[[#footnote-058|99]]''' ( ''high confidence'' ). Most observed adaptation is fragmented, small in scale, incremental, sector-specific, and focused more on planning rather than implementation. ( ''high confidence'' ). Further, observed adaptation is unequally distributed across regions and the largest adaptation gaps exist among lower population income groups ( ''high confidence'' ). In the urban context, the largest adaptation gaps exist in projects that manage complex risks, for example in the food–energy–water–health nexus or the inter-relationships of air quality and climate risk ( ''high'' . ''confidence'' ). Many funding, knowledge and practice gaps remain for effective implementation, monitoring and evaluation and current adaptation efforts are not expected to meet existing goals ( ''high confidence'' ). At current rates of adaptation planning and implementation the adaptation gap will continue to grow ( ''high confidence'' ). { ''WGII SPM C.1, WGII SPM C.1.2, WGII SPM C.4.1, WGII TS.D.1.3, WGII TS.D.1.4'' } .

'''Soft and hard adaptation limits''' '''[[#footnote-057|100]] have already been reached in some sectors and regions, in spite of adaptation having buffered some climate impacts (''' '''''high confidence)''''' '''.''' Ecosystems already reaching hard adaptation limits include some warm water coral reefs, some coastal wetlands, some rainforests, and some polar and mountain ecosystems ( ''high confidence'' ). Individuals and households in low lying coastal areas in Australasia and Small Islands and smallholder farmers in Central and South America, Africa, Europe and Asia have reached soft limits. ( ''medium confidence'' ), resulting from financial, governance, institutional and policy constraints and can be overcome by addressing these constraints ( ''high confidence'' ). Transitioning from incremental to transformational adaptation can help overcome soft adaptation limits ( ''high confidence'' ). { ''WGII SPM C.3, WGII SPM C.3.1, WGII SPM C.3.2, WGII SPM C.3.3, WGII SPM.C.3.4, WGII 16 ES'' }

Adaptation does not prevent all losses and damages, even with effective adaptation and before reaching soft and hard limits. Losses and damages are unequally distributed across systems, regions and sectors and are not comprehensively addressed by current financial, governance and institutional arrangements, particularly in vulnerable developing countries.. ( ''high confidence'' ). { ''WGII SPM.C.3.5'' }

'''There is increased evidence of maladaptation''' '''[[#footnote-056|101]] in various sectors and regions.''' Examples of maladaptation are observed in urban areas (e.g., new urban infrastructure that cannot be adjusted easily or affordably), agriculture (e.g., using high-cost irrigation in areas projected to have more intense drought conditions), ecosystems (e.g. fire suppression in naturally fire-adapted ecosystems, or hard defences against flooding) and human settlements (e.g. stranded assets and vulnerable communities that cannot afford to shift away or adapt and require an increase in social safety nets). Maladaptation especially affects marginalised and vulnerable groups adversely (e.g., Indigenous Peoples, ethnic minorities, low-income households, people living in informal settlements), reinforcing and entrenching existing inequities. Maladaptation can be avoided by flexible, multi-sectoral, inclusive and long-term planning and implementation of adaptation actions with benefits to many sectors and systems. ( ''high confidence'' ). { ''WGII SPM C.4, WGII SPM C.4.3, WGII TS.D.3.1'' }

'''Systemic barriers constrain the implementation of adaptation options in vulnerable sectors, regions and social groups (''' '''''high confidence).''''' Key barriers include limited resources, lack of private-sector and civic engagement, insufficient mobilisation of finance, lack of political commitment, limited research and/or slow and low uptake of adaptation science and a low sense of urgency. Inequity and poverty also constrain adaptation, leading to soft limits and resulting in disproportionate exposure and impacts for most vulnerable groups ( ''high confidence'' ). The largest adaptation gaps exist among lower income population groups ( ''high confidence'' ). As adaptation options often have long implementation times, long-term planning and accelerated implementation, particularly in this decade, is important to close adaptation gaps, recognising that constraints remain for some regions ( ''high confidence'' ). Prioritisation of options and transitions from incremental to transformational adaptation are limited due to vested interests, economic lock-ins, institutional path dependencies and prevalent practices, cultures, norms and belief systems ( ''high confidence'' ). Many funding, knowledge and practice gaps remain for effective implementation, monitoring and evaluation of adaptation ( ''high confidence'' ), including, lack of climate literacy at all levels and limited availability of data and information ( ''medium confidence'' ); for example for Africa, severe climate data constraints and inequities in research funding and leadership reduce adaptive capacity ( ''very high confidence'' ). { ''WGII SPM C.1.2, WGII SPM C.3.1, WGII TS.D.1.3, WGII TS.D.1.5, WGII TS.D.2.4'' }

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==== 2.3.3. Lack of Finance as a Barrier to Climate Action ====

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'''Insufficient financing, and a lack of political frameworks and incentives for finance, are key causes of the implementation gaps for both mitigation and adaptation (''' '''''high confidence). Financial flows remained heavily focused on mitigation, are uneven, and have developed heterogeneously across regions and sectors (''''' '''''high confidence).''''' In 2018, public and publicly mobilised private climate finance flows from developed to developing countries were below the collective goal under the UNFCCC and Paris Agreement to mobilise USD 100 billion per year by 2020 in the context of meaningful mitigation action and transparency on implementation ( ''medium confidence'' ). Public and private finance flows for fossil fuels are still greater than those for climate adaptation and mitigation ( ''high confidence'' ). The overwhelming majority of tracked climate finance is directed towards mitigation ( ''very high confidence'' ). Nevertheless, 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'' ). Challenges remain for green bonds and similar products, in particular around integrity and additionality, as well as the limited applicability of these markets to many developing countries ( ''high confidence'' ). { ''WGII SPM C.3.2, WGII SPM C.5.4; WGIII SPM B.5.4, WGIII SPM E.5.1'' }

Current global financial flows for adaptation including from public and private finance sources, are insufficient for and constrain implementation of adaptation options, especially in developing countries. ( ''high confidence'' ). There are widening disparities between the estimated costs of adaptation and the documented finance allocated to adaptation ( ''high confidence'' ). Adaptation finance needs are estimated to be higher than those assessed in AR5, and the enhanced mobilisation of and access to financial resources are essential for implementation of adaptation and to reduce adaptation gaps ( ''high confidence'' ). Annual finance flows targeting adaptation for Africa, for example, are billions of USD less than the lowest adaptation cost estimates for near-term climate change ( ''high confidence'' ). Adverse climate impacts can further reduce the availability of financial resources by causing losses and damages and impeding national economic growth, thereby further increasing financial constraints for adaptation particularly for developing countries and LDCs. ( ''medium confidence'' ). { ''WGII SPM C.1.2, WGII SPM C.3.2, WGII SPM C.5.4, WGII TS.D.1.6'' } .

Without effective mitigation and adaptation, losses and damages will continue to disproportionately affect the poorest and most vulnerable populations. Accelerated financial support for developing countries from developed countries and other sources is a critical enabler to enhance mitigation action { WGIII SPM. E.5.3 } . Many developing countries lack comprehensive data at the scale needed and lack adequate financial resources needed for adaptation for reducing associated economic and non-economic losses and damages. ( ''high confidence'' ). { ''WGII Cross-Chapter Box LOSS, WGII SPM C.3.1, WGII SPM C.3.2, WGII TS.D.1.3, WGII TS.D.1.5; WGIII SPM E.5.3'' }

'''There are barriers to redirecting capital towards climate action both within and outside the global financial sector.''' These barriers include: the 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. Challenges from outside the financial sector include: limited local capital markets; unattractive risk-return profiles, in particular due to missing or weak regulatory environments that are inconsistent 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'' ) { ''WGII SPM C.5.4; WGIII SPM E.5.2; SR1.5 SPM D.5.2'' }

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'''Cross-Section Box.2: Scenarios, Global Warming Levels, and Risks'''

Modelled scenarios and pathways '''[[#footnote-055|102]]''' are used to explore future emissions, climate change, related impacts and risks, and possible mitigation and adaptation strategies and are based on a range of assumptions, including socio-economic variables and mitigation options. These are quantitative projections and are neither predictions nor forecasts. Global modelled emission pathways, including those based on cost effective approaches contain regionally differentiated assumptions and outcomes, and have to be assessed with the careful recognition of these assumptions. Most do not make explicit assumptions about global equity, environmental justice or intra-regional income distribution. 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 '''[[#footnote-054|103]]''' . { ''WGI Box SPM.1; WGII Box SPM.1; WGIII Box SPM.1; SROCC Box SPM.1; SRCCL Box SPM.1'' } .

'''Socio-economic Development, Scenarios, and Pathways'''

The five Shared Socio-economic Pathways (SSP1 to SSP5) were designed to span a range of challenges to climate change mitigation and adaptation. For the assessment of climate impacts, risk and adaptation, the SSPs are used for future exposure, vulnerability and challenges to adaptation. Depending on levels of GHG mitigation, modelled emissions scenarios based on the SSPs can be consistent with low or high warming levels '''[[#footnote-053|104]]''' . There are many different mitigation strategies that could be consistent with different levels of global warming in 2100 (see Figure 4.1). { ''WGI Box SPM.1; WGII Box SPM.1; WGIII Box SPM.1, WGIII Box TS.5, WGIII Annex III; SRCCL Box SPM.1, SRCCL Figure SPM.2'' }

WGI assessed the climate response to five illustrative scenarios based on SSPs '''[[#footnote-052|105]]''' that cover the range of possible future development of anthropogenic drivers of climate change found in the literature. These scenarios combine socio-economic assumptions, levels of climate mitigation, land use and air pollution controls for aerosols and non- CH 4 ozone precursors. The high and very high GHG emissions scenarios (SSP3-7.0 and SSP5-8.5) have CO 2 emissions that roughly double from current levels by 2100 and 2050, respectively '''[[#footnote-051|106]]''' . The intermediate GHG emissions scenario (SSP2-4.5) has CO 2 emissions remaining around current levels until the middle of the century. The very low and low GHG emissions scenarios (SSP1-1.9 and SSP1-2.6) have CO 2 emissions declining to net zero around 2050 and 2070, respectively, followed by varying levels of net negative CO 2 emissions. In addition, Representative Concentration Pathways (RCPs) '''[[#footnote-050|107]]''' were used by WGI and WGII to assess regional climate changes, impacts and risks. { ''WGI BoxSPM.1'' } ( ''Cross-Section Box.2 Figure 1'' )

In WGIII, a large number of global modelled emissions pathways were assessed, of which 1202 pathways were categorised based on their projected global warming over the 21st century, with categories ranging from pathways that limit warming to 1.5°C with more than 50% likelihood '''[[#footnote-049|108]]''' with no or limited overshoot (C1) to pathways that exceed 4°C (C8). Methods to project global warming associated with the modelled pathways were updated to ensure consistency with the AR6 WGI assessment of the climate system response '''[[#footnote-048|109]]''' . { ''WGIII Box SPM.1,WGIII Table 3.1'' } . ( ''Table 3.1, Cross-Section Box.2 Figure 1'' )

'''Global Warming Levels (GWLs)'''

For many climate and risk variables, the geographical patterns of changes in climatic impact-drivers '''[[#footnote-047|110]]''' and climate impacts for a level of global warming '''[[#footnote-046|111]]''' are common to all scenarios considered and independent of timing when that level is reached. This motivates the use of GWLs as a dimension of integration. { ''WGI Box SPM.1.4, WGI TS.1.3.2; WGII Box SPM.1'' } ( ''Figure 3.1, Figure 3.2'' )

'''Risks'''

Dynamic interactions between climate-related hazards, exposure and vulnerability of the affected human society, species, or ecosystems result in risks arising from climate change. AR6 assesses key risks across sectors and regions as well as providing an updated assessment of the Reasons for Concern (RFCs) – five globally aggregated categories of risk that evaluate risk accrual with increasing global surface temperature. Risks can also arise from climate change mitigation or adaptation responses when the response does not achieve its intended objective, or when it results in adverse effects for other societal objectives. { ''WGII SPM A, WGII Figure SPM.3, WGII Box TS.1, WGII Figure TS.4; SR1.5 Figure SPM.2; SROCC Errata Figure SPM.3; SRCCL Figure SPM.2'' } ( ''3.1.2, Cross-Section Box.2 Figure 1, Figure 3.3'' )

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[[File:cd5731fe0df129fa508da850d6fdcb4c IPCC_AR6_SYR_CSB_2_Figure_1.png]]
\* The terminology SSPx-y is used, where ‘SSPx’ refers to the Shared Socio-economic Pathway or ‘SSP’ describing the socio-economic trends underlying the scenario, and ‘y’ refers to the approximate level of radiative forcing (in watts per square metre, or Wm ''–2'' ) resulting from the scenario in the year 2100.

\** The AR5 scenarios (RCPy), which partly inform the AR6 WGI and WGII assessments, are indexed to a similar set of approximate 2100 radiative forcing levels (in W m ''-2'' ). The SSP scenarios cover a broader range of GHG and air pollutant futures than the RCPs. They are similar but not identical, with differences in concentration trajectories for different GHGs. The overall radiative forcing tends to be higher for the SSPs compared to the RCPs with the same label ( ''medium confidence'' ). { ''WGI TS.1.3.1'' }

\*** Limited overshoot refers to exceeding 1.5°C global warming by up to about 0.1°C, high overshoot by 0.1°C-0.3°C, in both cases for up to several decades.

'''Cross-Section Box.2 Figure 1: Schematic of the AR6 framework for assessing future greenhouse gas emissions, climate change, risks, impacts and mitigation. Panel (a)''' The integrated framework encompasses socio-economic development and policy, emissions pathways and global surface temperature responses to the five scenarios considered by WGI (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) and eight global mean temperature change categorisations (C1–C8) assessed by WGIII, and the WGII risk assessment. The dashed arrow indicates that the influence from impacts/ risks to socio-economic changes is not yet considered in the scenarios assessed in the AR6. Emissions include GHGs, aerosols, and ozone precursors. CO 2 emissions are shown as an example on the left. The assessed global surface temperature changes across the 21st century relative to 1850-1900 for the five GHG emissions scenarios are shown as an example in the centre. ''Very likely'' ranges are shown for SSP1-2.6 and SSP3-7.0. Projected temperature outcomes at 2100 relative to 1850-1900 are shown for C1 to C8 categories with median (line) and the combined ''very likely'' range across scenarios (bar). On the right, future risks due to increasing warming are represented by an example ‘burning ember’ figure (see 3.1.2 for the definition of RFC1). '''Panel (b)''' Description and relationship of scenarios considered across AR6 Working Group reports. '''Panel (c)''' Illustration of risk arising from the interaction of hazard (driven by changes in climatic impact-drivers) with vulnerability, exposure and response to climate change. { ''WGI TS1.4, Figure 4.11; WGII Figure 1.5, WGII Figure 14.8; WGIII Table SPM.2, WGIII Figure 3.11'' }

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