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

=== 4.9 Integration of Near-Term Actions Across Sectors and Systems ===

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'''The feasibility, effectiveness and benefits of mitigation and adaptation actions are increased when multi-sectoral solutions are undertaken that cut across systems. When such options are combined with broader sustainable development objectives, they can yield greater benefits for human well-being, social equity and justice, and ecosystem and planetary health. ( '''''high confidence''''' )'''
'''Climate resilient development strategies that treat climate, ecosystems and biodiversity, and human society as parts of an integrated system are the most effective (''' '''''high confidence)''''' '''''.''''' Human and ecosystem vulnerability are interdependent ( ''high confidence'' ). Climate resilient development is enabled when decision-making processes and actions are integrated across sectors. ( ''very high confidence'' ). Synergies with and progress towards the Sustainable Development Goals enhance prospects for climate resilient development. Choices and actions that treat humans and ecosystems as an integrated system build on diverse knowledge about climate risk, equitable, just and inclusive approaches, and ecosystem stewardship. { ''WGII SPM B.2, WGII Figure SPM.5, WGII SPM D.2, WGII SPM D2.1, WGII SPM 2.2, WGII SPM D4, WGII SPM D4.1, WGII SPM D4.2, WGII SPM D5.2, WGII Figure SPM.5'' }

'''Approaches that align goals and actions across sectors provide opportunities for multiple and large-scale benefits and avoided damages in the near term. Such measures can also achieve greater benefits through cascading effects across sectors (''' '''''medium confidence)''''' '''''.''''' For example, the feasibility of using land for both agriculture and centralised solar production can increase when such options are combined ( ''high confidence'' ). Similarly, integrated transport and energy infrastructure planning and operations can together reduce the environmental, social, and economic impacts of decarbonising the transport and energy sectors ( ''high confidence'' ). The implementation of packages of multiple city-scale mitigation strategies can have cascading effects across sectors and reduce GHG emissions both within and outside a city’s administrative boundaries ( ''very high confidence'' ). Integrated design approaches to the construction and retrofit of buildings provide increasing examples of zero energy or zero carbon buildings in several regions. To minimise maladaptation, multi-sectoral, multi-actor and inclusive planning with flexible pathways encourages low-regret and timely actions that keep options open, ensure benefits in multiple sectors and systems and suggest the available solution space for adapting to long-term climate change. ( ''very high confidence'' ). Trade-offs in terms of employment, water use, land-use competition and biodiversity, as well as access to, and the affordability of, energy, food, and water can be avoided by well-implemented land-based mitigation options, especially those that do not threaten existing sustainable land uses and land rights, with frameworks for integrated policy implementation ( ''high confidence'' ). { ''WGII SPM C.2, WGII SPM C.4.4; WGIII SPM C.6.3, WGIII SPM C.6, WGIII SPM C.7.2, WGIII SPM C.8.5, WGIII SPM D.1.2, WGIII SPM D.1.5, WGIII SPM E.1.2'' }

'''Mitigation and adaptation when implemented together, and combined with broader sustainable development objectives, would yield multiple benefits for human well-being as well as ecosystem and planetary health (''' '''''high confidence)''''' '''''.''''' The range of such positive interactions is significant in the landscape of near-term climate policies across regions, sectors and systems. For example, AFOLU mitigation actions in land-use change and forestry, when sustainably implemented, can provide large-scale GHG emission reductions and removals that simultaneously benefit biodiversity, food security, wood supply and other ecosystem services but cannot fully compensate for delayed mitigation action in other sectors. Adaptation measures in land, ocean and ecosystems similarly can have widespread benefits for food security, nutrition, health and well-being, ecosystems and biodiversity. Equally, urban systems are critical, interconnected sites for climate resilient development; urban policies that implement multiple interventions can yield adaptation or mitigation gains with equity and human well-being. Integrated policy packages can improve the ability to integrate considerations of equity, gender equality and justice. Coordinated cross-sectoral policies and planning can maximise synergies and avoid or reduce trade-offs between mitigation and adaptation. Effective action in all of the above areas will require near-term political commitment and follow-through, social cooperation, finance, and more integrated cross-sectoral policies and support and actions. ( ''high confidence'' ). { ''WGII SPM C.1, WGII SPM C.2, WGII SPM C.2, WGII SPM C.5, WGII SPM D.2, WGII SPM D.3.2, WGII SPM D.3.3, WGII Figure SPM.4; WGIII SPM C.6.3, WGIII SPM C.8.2, WGIII SPM C.9, WGIII SPM C.9.1, WGIII SPM C.9.2, WGIII SPM D.2, WGIII SPM D.2.4, WGIII SPM D.3.2, WGIII SPM E.1, WGIII SPM E.2.4, WGIII Figure SPM.8, WGIII TS.7, WGIII TS Figure TS.29: SRCCL ES 7.4.8, SRCCL SPM B.6'' } ( ''3.4, 4.4'' )

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[[#footnote-156-backlink|1]] 1 The three Working Group contributions to AR6 are: AR6 Climate Change 2021: The Physical Science Basis; AR6 Climate Change 2022: Impacts, Adaptation and Vulnerability; and AR6 Climate Change 2022: Mitigation of Climate Change. Their assessments cover scientific literature accepted for publication respectively by 31 January 2021, 1 September 2021 and 11 October 2021.

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[[#footnote-155-backlink|2]] 2 The three Special Reports are: Global Warming of 1.5°C (2018): 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 (SR1.5); Climate Change and Land (2019): an IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems (SRCCL); and The Ocean and Cryosphere in a Changing Climate (2019) (SROCC). The Special Reports cover scientific literature accepted for publication respectively by 15 May 2018, 7 April 2019 and 15 May 2019.

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[[#footnote-154-backlink|3]] 3 In this report, the near term is defined as the period until 2040. The long term is defined as the period beyond 2040.

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[[#footnote-153-backlink|4]] Each finding is grounded in an evaluation of underlying evidence and agreement. The IPCC calibrated language uses five qualifiers to express a level of confidence: very low, low, medium, high and very high, and typeset in italics, for example, ''medium confidence'' . The following terms are used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66–100%, more likely than not &gt;50–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely 95–100%; and extremely unlikely 0–5%) are also used when appropriate. Assessed likelihood is typeset in italics, e.g., ''very likely'' . This is consistent with AR5 and the other AR6 Reports.

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[[#footnote-152-backlink|5]] 5 Ranges given throughout the SPM represent ''very likely'' ranges (5–95% range) unless otherwise stated.

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[[#footnote-151-backlink|6]] The estimated increase in global surface temperature since AR5 is principally due to further warming since 2003–2012 (0.19 [0.16 to 0.22]°C). Additionally, methodological advances and new datasets have provided a more complete spatial representation of changes in surface temperature, including in the Arctic. These and other improvements have also increased the estimate of global surface temperature change by approximately 0.1°C, but this increase does not represent additional physical warming since AR5.

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[[#footnote-150-backlink|7]] The period distinction with A.1.1 arises because the attribution studies consider this slightly earlier period. The observed warming to 2010–2019 is 1.06 [0.88 to 1.21]°C.

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[[#footnote-149-backlink|8]] Contributions from emissions to the 2010–2019 warming relative to 1850–1900 assessed from radiative forcing studies are: CO 2 0.8 [0.5 to 1.2] °C; methane 0.5 [0.3 to 0.8]°C; nitrous oxide 0.1 [0.0 to 0.2]°C and fluorinated gases 0.1 [0.0 to 0.2]°C. {2.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-148-backlink|9]] 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 -equivalents (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 AR6 WGI and WGIII reports contain updated emission metric values, evaluations of different metrics with regard to mitigation objectives, and assess new approaches to aggregating gases. 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.. {2.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-147-backlink|10]] GHG emission levels are rounded to two significant digits; as a consequence, small differences in sums due to rounding may occur. {2.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-146-backlink|11]] Territorial emissions.

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[[#footnote-145-backlink|12]] Acute food insecurity can occur at any time with a severity that threatens lives, livelihoods or both, regardless of the causes, context or duration, as a result of shocks risking determinants of food security and nutrition, and is used to assess the need for humanitarian action.. {2.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-144-backlink|13]] In this report, the term ‘losses and damages’ refers to adverse observed impacts and/or projected risks and can be economic and/or non-economic (see Annex I: Glossary).

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[[#footnote-143-backlink|14]] Slow-onset events are described among the climatic-impact drivers of the AR6 WGI and refer to the risks and impacts associated with e.g., increasing temperature means, desertification, decreasing precipitation, loss of biodiversity, land and forest degradation, glacial retreat and related impacts, ocean acidification, sea level rise and salinization. {2.1.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-142-backlink|15]] Effectiveness refers here to the extent to which an adaptation option is anticipated or observed to reduce climate-related risk.. {2.2.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-141-backlink|16]] See Annex I: Glossary. {2.2.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-140-backlink|17]] Ecosystem-based Adaptation (EbA) is recognized internationally under the Convention on Biological Diversity (CBD14/5). A related concept is Nature-based Solutions (NbS), see Annex I: Glossary.

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[[#footnote-139-backlink|18]] Incremental adaptations to change in climate are understood as extensions of actions and behaviours that already reduce the losses or enhance the benefits of natural variations in extreme weather/climate events. {2.3.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-138-backlink|19]] In the literature, the terms pathways and scenarios are used interchangeably, with the former more frequently used in relation to climate goals. WGI primarily used the term scenarios and WGIII mostly used the term modelled emission and mitigation pathways. The SYR primarily uses scenarios when referring to WGI and modelled emission and mitigation pathways when referring to WGIII.

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[[#footnote-137-backlink|20]] Around half of all modelled global emission pathways assume cost-effective approaches that rely on least-cost mitigation/abatement options globally. The other half looks at existing policies and regionally and sectorally differentiated actions.

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[[#footnote-136-backlink|21]] SSP-based scenarios are referred to as SSPx-y, where ‘SSPx’ refers to the Shared Socioeconomic Pathway describing the socioeconomic trends underlying the scenarios, and ‘y’ refers to the level of radiative forcing (in watts per square metre, or W m ''-2'' ) resulting from the scenario in the year 2100.. { Cross-Section Box.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-135-backlink|22]] Very high emissions scenarios have become ''less likely'' but cannot be ruled out. Warming levels &gt;4°C may result from very high emissions scenarios, but can also occur from lower emission scenarios if climate sensitivity or carbon cycle feedbacks are higher than the best estimate. {3.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-134-backlink|23]] RCP-based scenarios are referred to as RCPy, where ‘y’ refers to the level of radiative forcing (in watts per square metre, or W m ''-2'' ) resulting from the scenario in the year 2100. The SSP scenarios cover a broader range of greenhouse gas and air pollutant futures than the RCPs. They are similar but not identical, with differences in concentration trajectories. The overall effective radiative forcing tends to be higher for the SSPs compared to the RCPs with the same label (medium confidence ) . { Cross-Section Box.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-133-backlink|24]] At least 1.8 GtCO 2 -eq yr ''–1'' can be accounted for by aggregating separate estimates for the effects of economic and regulatory instruments. Growing numbers of laws and executive orders have impacted global emissions and were estimated to result in 5.9 GtCO 2 -eq yr ''–1'' less emissions in 2016 than they otherwise would have been.. (medium confidence ) . {2.2.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-132-backlink|25]] Reductions were linked to energy supply decarbonisation, energy efficiency gains, and energy demand reduction, which resulted from both policies and changes in economic structure ( high confidence ) . {2.2.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-131-backlink|26]] Due to the literature cutoff date of WGIII, the additional NDCs submitted after 11 October 2021 are not assessed here.. {Footnote 32 in the Longer Report &lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-130-backlink|27]] Projected 2030 GHG emissions are 50 (47–55) GtCO 2 -eq if all conditional NDC elements are taken into account. Without conditional elements, the global emissions are projected to be approximately similar to modelled 2019 levels at 53 (50–57) GtCO 2 -eq. {2.3.1, Table 2.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-129-backlink|28]] Global warming (see Annex I: Glossary) is here reported as running 20-year averages, unless stated otherwise, relative to 1850–1900. Global surface temperature in any single year can vary above or below the long-term human-caused trend, due to natural variability. The internal variability of global surface temperature in a single year is estimated to be about ±0.25°C (5–95% range, ''high confidence'' ). The occurrence of individual years with global surface temperature change above a certain level does not imply that this global warming level has been reached.. {4.3, Cross-Section Box.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-128-backlink|29]] Median five-year interval at which a 1.5°C global warming level is reached (50% probability) in categories of modelled pathways considered in WGIII is 2030–2035. By 2030, global surface temperature in any individual year could exceed 1.5°C relative to 1850–1900 with a probability between 40% and 60%, across the five scenarios assessed in WGI (medium confidence ) . In all scenarios considered in WGI except the very high emissions scenario (SSP5-8.5), the midpoint of the first 20-year running average period during which the assessed average global surface temperature change reaches 1.5°C lies in the first half of the 2030s. In the very high GHG emissions scenario, the midpoint is in the late 2020s. {3.1.1, 3.3.1, 4.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} (Box SPM.1 )

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[[#footnote-127-backlink|30]] The best estimates [and ''very likely'' ranges] for the different scenarios are: 1.4 [1.0 to 1.8 ]°C (SSP1-1.9); 1.8 [1.3 to 2.4]°C (SSP1-2.6); 2.7 [2.1 to 3.5]°C (SSP2-4.5); 3.6 [2.8 to 4.6]°C (SSP3-7.0); and 4.4 [3.3 to 5.7 ]°C (SSP5-8.5).. {3.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} (Box SPM.1 )

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[[#footnote-126-backlink|31]] Assessed future changes in global surface temperature have been constructed, for the first time, by combining multi-model projections with observational constraints and the assessed equilibrium climate sensitivity and transient climate response. The uncertainty range is narrower than in the AR5 thanks to improved knowledge of climate processes, paleoclimate evidence and model-based emergent constraints.. {3.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-125-backlink|32]] See Annex I: Glossary. Natural variability includes natural drivers and internal variability. The main internal variability phenomena include El Niño-Southern Oscillation, Pacific Decadal Variability and Atlantic Multi-decadal Variability.. {4.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-124-backlink|33]] Based on additional scenarios.

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[[#footnote-123-backlink|34]] Permafrost, seasonal snow cover, glaciers, the Greenland and Antarctic Ice Sheets, and Arctic sea ice.

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[[#footnote-122-backlink|35]] Based on 2500-year reconstructions, eruptions with a radiative forcing more negative than –1 W m ''-2'' , related to the radiative effect of volcanic stratospheric aerosols in the literature assessed in this report, occur on average twice per century. {4.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-121-backlink|36]] In all assessed regions.

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[[#footnote-120-backlink|37]] Undetectable risk level indicates no associated impacts are detectable and attributable to climate change; moderate risk indicates associated impacts are both detectable and attributable to climate change with at least ''medium confidence'' , also accounting for the other specific criteria for key risks; high risk indicates severe and widespread impacts that are judged to be high on one or more criteria for assessing key risks; and very high risk level indicates very high risk of severe impacts and the presence of significant irreversibility or the persistence of climate-related hazards, combined with limited ability to adapt due to the nature of the hazard or impacts/risks.. {3.1.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-119-backlink|38]] The Reasons for Concern (RFC) framework communicates scientific understanding about accrual of risk for five broad categories. RFC1: Unique and threatened systems: ecological and human systems that have restricted geographic ranges constrained by climate-related conditions and have high endemism or other distinctive properties. RFC2: Extreme weather events: risks/impacts to human health, livelihoods, assets and ecosystems from extreme weather events. RFC3: Distribution of impacts: risks/impacts that disproportionately affect particular groups due to uneven distribution of physical climate change hazards, exposure or vulnerability. RFC4: Global aggregate impacts: impacts to socio-ecological systems that can be aggregated globally into a single metric. RFC5: Large-scale singular events: relatively large, abrupt and sometimes irreversible changes in systems caused by global warming. See also Annex I: Glossary. {3.1.2, Cross-Section Box.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-118-backlink|39]] Net zero GHG emissions defined by the 100-year global warming potential. See footnote 9.

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[[#footnote-117-backlink|40]] Global databases make different choices about which emissions and removals occurring on land are considered anthropogenic. Most countries report their anthropogenic land CO 2 fluxes including fluxes due to human-caused environmental change (e.g., CO 2 fertilisation) on ‘managed’ land in their national GHG inventories. Using emissions estimates based on these inventories, the remaining carbon budgets must be correspondingly reduced. {3.3.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-116-backlink|41]] For example, remaining carbon budgets could be 300 or 600 GtCO 2 for 1.5°C (50%), respectively for high and low non-CO 2 emissions, compared to 500 GtCO 2 in the central case. {3.3.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-115-backlink|42]] Abatement here refers to human interventions that reduce the amount of greenhouse gases that are released from fossil fuel infrastructure to the atmosphere.

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[[#footnote-114-backlink|43]] Ibid.

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[[#footnote-113-backlink|44]] WGI provides carbon budgets that are in line with limiting global warming to temperature limits with different likelihoods, such as 50%, 67% or 83%. {3.3.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-112-backlink|45]] Uncertainties for total carbon budgets have not been assessed and could affect the specific calculated fractions.

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[[#footnote-111-backlink|46]] Ibid.

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[[#footnote-110-backlink|47]] CCS is an option to reduce emissions from large-scale fossil-based energy and industry sources provided geological storage is available. When CO 2 is captured directly from the atmosphere (DACCS), or from biomass (BECCS), CCS provides the storage component of these CDR methods. CO 2 capture and subsurface injection is a mature technology for gas processing and enhanced oil recovery. In contrast to the oil and gas sector, CCS is less mature in the power sector, as well as in cement and chemicals production, where it is a critical mitigation option. The technical geological storage capacity is estimated to be on the order of 1000 GtCO 2 , which is more than the CO 2 storage requirements through 2100 to limit global warming to 1.5°C, although the regional availability of geological storage could be a limiting factor. If the geological storage site is appropriately selected and managed, it is estimated that the CO 2 can be permanently isolated from the atmosphere. Implementation of CCS currently faces technological, economic, institutional, ecological-environmental and socio-cultural barriers. Currently, global rates of CCS deployment are far below those in modelled pathways limiting global warming to 1.5°C to 2°C. Enabling conditions such as policy instruments, greater public support and technological innovation could reduce these barriers. (high confidence ) . {3.3.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-109-backlink|48]] The impacts, risks, and co-benefits of CDR deployment for ecosystems, biodiversity and people will be highly variable depending on the method, site-specific context, implementation and scale (high confidence ) .

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[[#footnote-108-backlink|49]] The southern part of Mexico is included in the climatic subregion South Central America (SCA) for WGI. Mexico is assessed as part of North America for WGII. The climate change literature for the SCA region occasionally includes Mexico, and in those cases WGII assessment makes reference to Latin America. Mexico is considered part of Latin America and the Caribbean for WGIII.

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[[#footnote-107-backlink|50]] The evidence is too limited to make a similar robust conclusion for limiting warming to 1.5°C. Limiting global warming to 1.5°C instead of 2°C would increase the costs of mitigation, but also increase the benefits in terms of reduced impacts and related risks, and reduced adaptation needs ( high confidence ) .

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[[#footnote-106-backlink|51]] 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.

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[[#footnote-105-backlink|52]] 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. {4.5.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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[[#footnote-104-backlink|53]] ‘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.

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[[#footnote-103-backlink|54]] Fossil fuel subsidy removal is projected by various studies to reduce global CO 2 emission by 1 to 4%, and GHG emissions by up to 10% by 2030, varying across regions (medium confidence ) .

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[[#footnote-102-backlink|55]] Finance originates from diverse sources: public or private, local, national or international, bilateral or multilateral, and alternative sources. It can take the form of grants, technical assistance, loans (concessional and non-concessional), bonds, equity, risk insurance and financial guarantees (of different types).

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[[#footnote-101-backlink|56]] These estimates rely on scenario assumptions.

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[[#footnote-100-backlink|57]] Leading to lower net emission reductions or even emission increases.

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[[#footnote-099-backlink|58]] The three Working Group contributions to AR6 are: Climate Change 2021: The Physical Science Basis; Climate Change 2022: Impacts, Adaptation and Vulnerability; and Climate Change 2022: Mitigation of Climate Change, respectively. Their assessments cover scientific literature accepted for publication respectively by 31 January 2021, 1 September 2021 and 11 October 2021.

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[[#footnote-098-backlink|59]] The three Special Reports are : Global Warming of 1.5°C (2018): 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 (SR1.5); Climate Change and Land (2019): an IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems (SRCCL); and The Ocean and Cryosphere in a Changing Climate (2019) (SROCC). The Special Reports cover scientific literature accepted for publication respectively by 15 May 2018, 7 April 2019 and 15 May 2019.

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[[#footnote-097-backlink|60]] The Glossary (Annex I) includes definitions of these, and other terms and concepts used in this report drawn from the AR6 joint Working Group Glossary.

<div id="footnote-096" class="_idFootnote"></div>

[[#footnote-096-backlink|61]] Depending on the climate information context, geographical regions in AR6 may refer to larger areas, such as sub-continents and oceanic regions, or to typological regions, such as monsoon regions, coastlines, mountain ranges or cities. A new set of standard AR6 WGI reference land and ocean regions have been defined. WGIII allocates countries to geographical regions, based on the UN Statistics Division Classification {&lt;span class=&quot;CharOverride-4&quot;&gt;WGI 1.4.5, WGI 10.1, WGI 11.9, WGI 12.1–12.4, WGI Atlas.1.3.3–1.3.4&lt;/span&gt;} .

<div id="footnote-095" class="_idFootnote"></div>

[[#footnote-095-backlink|62]] Each finding is grounded in an evaluation of underlying evidence and agreement. A level of confidence is expressed using five qualifiers: very low, low, medium, high and very high, and typeset in italics, for example, ''medium confidence'' . The following terms have been used to indicate the assessed likelihood of an outcome or result: virtually certain 99–100% probability; very likely 90–100%; likely 66–100%; more likely than not &gt;50-100%; about as likely as not 33–66%; unlikely 0–33%; very unlikely 0–10%; and exceptionally unlikely 0–1%. Additional terms (extremely likely 95–100% and extremely unlikely 0–5%) are also used when appropriate. Assessed likelihood also is typeset in italics: for example, very likely . This is consistent with AR5. In this Report, unless stated otherwise, square brackets [x to y] are used to provide the assessed ''very likely'' range, or 90% interval.

<div id="footnote-094" class="_idFootnote"></div>

[[#footnote-094-backlink|63]] In this report, the term ‘losses and damages’ refers to adverse observed impacts and/or projected risks and can be economic and/or non-economic. (See Annex I: Glossary)

<div id="footnote-093" class="_idFootnote"></div>

[[#footnote-093-backlink|64]] 63 In this report, the term ‘losses and damages’ refers to adverse observed impacts and/or projected risks and can be economic and/or non-economic. (See Annex I: Glossary)

The estimated increase in global surface temperature since AR5 is principally due to further warming since 2003 – 2012 (+0.19 [0.16 to 0.22]°C). Additionally, methodological advances and new datasets have provided a more complete spatial representation of changes in surface temperature, including in the Arctic. These and other improvements have also increased the estimate of global surface temperature change by approximately 0.1°C, but this increase does not represent additional physical warming since AR5 {WGI SPM A1.2 and footnote 10&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-092" class="_idFootnote"></div>

[[#footnote-092-backlink|65]] For 1850–1900 to 2013–2022 the updated calculations are 1.15 [1.00 to 1.25]°C for global surface temperature, 1.65 [1.36 to 1.90]°C for land temperatures and 0.93 [0.73 to 1.04]°C for ocean temperatures above 1850 – 1900 using the exact same datasets (updated by 2 years) and methods as employed in WGI.

<div id="footnote-091" class="_idFootnote"></div>

[[#footnote-091-backlink|66]] The period distinction with the observed assessment arises because the attribution studies consider this slightly earlier period. The observed warming to 2010 – 2019 is 1.06 [0.88 to 1.21]°C. {WGI SPM footnote 11&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-090" class="_idFootnote"></div>

[[#footnote-090-backlink|67]] Contributions from emissions to the 2010 – 2019 warming relative to 1850 – 1900 assessed from radiative forcing studies are: CO 2 0.8 [0.5 to 1.2]°C; methane 0.5 [0.3 to 0.8]°C; nitrous oxide 0.1 [0.0 to 0.2]°C and fluorinated gases 0.1 [0.0 to 0.2]°C.

<div id="footnote-089" class="_idFootnote"></div>

[[#footnote-089-backlink|68]] For 2021 (the most recent year for which final numbers are available) concentrations using the same observational products and methods as in AR6 WGI are: 415 ppm CO 2 ; 1896 ppb CH 4 ; and 335 ppb N 2 O. Note that the CO 2 is reported here using the WMO-CO 2 -X2007 scale to be consistent with WGI. Operational CO 2 reporting has since been updated to use the WMO-CO 2 -X2019 scale.

<div id="footnote-088" class="_idFootnote"></div>

[[#footnote-088-backlink|69]] GHG emission metrics are used to express emissions of different GHGs in a common unit. Aggregated GHG emissions in this report are stated in CO 2 -equivalents (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 AR6 WGI and WGIII reports contain updated emission metric values, evaluations of different metrics with regard to mitigation objectives, and assess new approaches to aggregating gases. 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. {WGI SPM D.1.8, WGI 7.6; WGIII SPM B.1, WGIII Cross-Chapter Box 2.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} . (Annex I: Glossary )

<div id="footnote-087" class="_idFootnote"></div>

[[#footnote-087-backlink|70]] Territorial emissions

<div id="footnote-086" class="_idFootnote"></div>

[[#footnote-086-backlink|71]] GHG emission levels are rounded to two significant digits; as a consequence, small differences in sums due to rounding may occur. {WGIII SPM footnote 8&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-085" class="_idFootnote"></div>

[[#footnote-085-backlink|72]] 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 +5.9 (±4.1) GtCO 2 yr ''-1'' based on book-keeping models. {WGIII SPM Footnote 14&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-084" class="_idFootnote"></div>

[[#footnote-084-backlink|73]] 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. {WGIII SPM footnote 15&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-083" class="_idFootnote"></div>

[[#footnote-083-backlink|74]] ‘Main driver’ means responsible for more than 50% of the change. {WGI SPM footnote 12&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-082" class="_idFootnote"></div>

[[#footnote-082-backlink|75]] See Annex I: Glossary.

<div id="footnote-081" class="_idFootnote"></div>

[[#footnote-081-backlink|76]] Based on scientific understanding, key findings can be formulated as statements of fact or associated with an assessed level of confidence indicated using the IPCC calibrated language.

<div id="footnote-080" class="_idFootnote"></div>

[[#footnote-080-backlink|77]] Balanced diets feature plant-based foods, such as those based on coarse grains, legumes fruits and vegetables, nuts and seeds, and animal-source foods produced in resilient, sustainable and low-GHG emissions systems, as described in SRCCL. {WGII SPM Footnote 32&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-079" class="_idFootnote"></div>

[[#footnote-079-backlink|78]] Acute food insecurity can occur at any time with a severity that threatens lives, livelihoods or both, regardless of the causes, context or duration, as a result of shocks risking determinants of food security and nutrition, and is used to assess the need for humanitarian action. {WGII SPM, footnote 30&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-078" class="_idFootnote"></div>

[[#footnote-078-backlink|79]] Slow-onset events are described among the climatic-impact drivers of the AR6 WGI and refer to the risks and impacts associated with e.g., increasing temperature means, desertification, decreasing precipitation, loss of biodiversity, land and forest degradation, glacial retreat and related impacts, ocean acidification, sea level rise and salinization. {WGII SPM footnote 29&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-077" class="_idFootnote"></div>

[[#footnote-077-backlink|80]] See Annex 1: Glossary.

<div id="footnote-076" class="_idFootnote"></div>

[[#footnote-076-backlink|81]] Governance: The structures, processes and actions through which private and public actors interact to address societal goals. This includes formal and informal institutions and the associated norms, rules, laws and procedures for deciding, managing, implementing and monitoring policies and measures at any geographic or political scale, from global to local. {WGII SPM Footnote 31&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-075" class="_idFootnote"></div>

[[#footnote-075-backlink|82]] See Annex I: Glossary.

<div id="footnote-074" class="_idFootnote"></div>

[[#footnote-074-backlink|83]] Documented adaptation refers to published literature on adaptation policies, measures and actions that has been implemented and documented in peer reviewed literature, as opposed to adaptation that may have been planned, but not implemented.

<div id="footnote-073" class="_idFootnote"></div>

[[#footnote-073-backlink|84]] Effectiveness refers here to the extent to which an adaptation option is anticipated or observed to reduce climate-related risk.

<div id="footnote-072" class="_idFootnote"></div>

[[#footnote-072-backlink|85]] See Annex I: Glossary.

<div id="footnote-071" class="_idFootnote"></div>

[[#footnote-071-backlink|86]] Irrigation is effective in reducing drought risk and climate impacts in many regions and has several livelihood benefits, but needs appropriate management to avoid potential adverse outcomes, which can include accelerated depletion of groundwater and other water sources and increased soil salinization (medium confidence ) .

<div id="footnote-070" class="_idFootnote"></div>

[[#footnote-070-backlink|87]] EbA is recognised internationally under the Convention on Biological Diversity (CBD14/5). A related concept is Nature-based Solutions (NbS), see Annex I: Glossary.

<div id="footnote-069" class="_idFootnote"></div>

[[#footnote-069-backlink|88]] The timing of various cut-offs for assessment differs by WG report and the aspect assessed. See footnote 1 in Section 1.

<div id="footnote-068" class="_idFootnote"></div>

[[#footnote-068-backlink|89]] See CSB.2 for a discussion of scenarios and pathways.

<div id="footnote-067" class="_idFootnote"></div>

[[#footnote-067-backlink|90]] See Annex I: Glossary.

<div id="footnote-066" class="_idFootnote"></div>

[[#footnote-066-backlink|91]] 88 The timing of various cut-offs for assessment differs by WG report and the aspect assessed. See footnote 58 in Section 1.

89 See CSB.2 for a discussion of scenarios and pathways.

90 See Annex I: Glossary.

NDCs announced prior to COP26 refer to the most recent NDCs submitted to the UNFCCC up to the literature cut-off date of the WGIII 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. {WGIII SPM footnote 24&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-065" class="_idFootnote"></div>

[[#footnote-065-backlink|92]] 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 3.1. 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 3.1). {WGIII SPM footnote 26&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-064" class="_idFootnote"></div>

[[#footnote-064-backlink|93]] 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. {WGIII SPM footnote 27&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-063" class="_idFootnote"></div>

[[#footnote-063-backlink|94]] Implementation gaps refer to how far currently enacted policies and actions fall short of reaching the pledges. 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. {WGIII Table 4.2, WGIII SPM footnote 25&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

<div id="footnote-062" class="_idFootnote"></div>

[[#footnote-062-backlink|95]] Abatement here refers to human interventions that reduce the amount of GHGs that are released from fossil fuel infrastructure to the atmosphere. ''{WGIII SPM footnote 34}''

<div id="footnote-061" class="_idFootnote"></div>

[[#footnote-061-backlink|96]] WGI provides carbon budgets that are in line with limiting global warming to temperature limits with different likelihoods, such as 50%, 67% or 83%. {WGI Table SPM.2}

<div id="footnote-060" class="_idFootnote"></div>

[[#footnote-060-backlink|97]] 95 Abatement here refers to human interventions that reduce the amount of GHGs that are released from fossil fuel infrastructure to the atmosphere. {WGIII SPM footnote 34&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

96 WGI provides carbon budgets that are in line with limiting global warming to temperature limits with different likelihoods, such as 50%, 67% or 83%. {WGI Table SPM.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

The 2019 range of harmonised GHG emissions across the pathways [53–58 GtCO 2 -eq] is within the uncertainty ranges of 2019 emissions assessed in WGIII [https://www.ipcc.ch/report/ar6/syr/longer-report/ Chapter 2] [53–66 GtCO 2 -eq].

<div id="footnote-059" class="_idFootnote"></div>

[[#footnote-059-backlink|98]] See footnote 12 above.

<div id="footnote-058" class="_idFootnote"></div>

[[#footnote-058-backlink|99]] See Annex I: Glossary.

<div id="footnote-057" class="_idFootnote"></div>

[[#footnote-057-backlink|100]] Adaptation limit: The point at which an actor’s objectives (or system needs) cannot be secured from intolerable risks through adaptive actions. Hard adaptation limit - No adaptive actions are possible to avoid intolerable risks. Soft adaptation limit - Options are currently not available to avoid intolerable risks through adaptive action.

<div id="footnote-056" class="_idFootnote"></div>

[[#footnote-056-backlink|101]] Maladaptation refers to actions that may lead to increased risk of adverse climate-related outcomes, including via increased greenhouse gas emissions, increased or shifted vulnerability to climate change, more inequitable outcomes, or diminished welfare, now or in the future. Most often, maladaptation is an unintended consequence. See Annex I: Glossary.

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

[[#footnote-055-backlink|102]] In the literature, the terms pathways and scenarios are used interchangeably, with the former more frequently used in relation to climate goals. WGI primarily used the term scenarios and WGIII mostly used the term modelled emissions and mitigation pathways. The SYR primarily uses scenarios when referring to WGI and modelled emissions and mitigation pathways when referring to WGIII. {WGI Box SPM.1; WGIII footnote 44&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-054-backlink|103]] Around half of all modelled global emissions pathways assume cost-effective approaches that rely on least-cost mitigation/abatement options globally. The other half look at existing policies and regionally and sectorally differentiated actions. 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 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). {WGIII Box SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-053-backlink|104]] High mitigation challenges, for example, due to assumptions of slow technological change, high levels of global population growth, and high fragmentation as in the Shared Socio-economic Pathway SSP3, may render modelled pathways that limit warming to 2°C (&gt; 67%) or lower infeasible. (medium confidence ). . {WGIII SPM C.1.4; SRCCL Box SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-052-backlink|105]] SSP-based scenarios are referred to as SSPx-y, where ‘SSPx’ refers to the Shared Socio-economic Pathway describing the socioeconomic trends underlying the scenarios, and ‘y’ refers to the level of radiative forcing (in watts per square metre, or Wm ''–2'' ) resulting from the scenario in the year 2100. {WGI SPM footnote 22&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-051-backlink|106]] Very high emission scenarios have become less ''likely'' but cannot be ruled out. Temperature levels &gt; 4°C may result from very high emission scenarios, but can also occur from lower emission scenarios if climate sensitivity or carbon cycle feedbacks are higher than the best estimate. {&lt;span class=&quot;CharOverride-4&quot;&gt;WGIII SPM C.1.3&lt;/span&gt;}

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

[[#footnote-050-backlink|107]] RCP-based scenarios are referred to as RCPy, where ‘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. {WGII SPM footnote 21&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-049-backlink|108]] Denoted ‘&gt;50%’ in this report.

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

[[#footnote-048-backlink|109]] The climate response to emissions is investigated with climate models, paleoclimatic insights and other lines of evidence. The assessment outcomes are used to categorise thousands of scenarios via simple physically-based climate models (emulators). {WGI TS.1.2.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-047-backlink|110]] See Annex I: Glossary

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

[[#footnote-046-backlink|111]] See Annex I: Glossary. Here, global warming is the 20-year average global surface temperature relative to 1850–1900. The assessed time of when a certain global warming level is reached under a particular scenario is defined here as the mid-point of the first 20-year running average period during which the assessed average global surface temperature change exceeds the level of global warming. {WGI SPM footnote 26, Cross-Section Box TS.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-045-backlink|112]] Understanding of climate processes, the instrumental record, paleoclimates and model-based emergent constraints (see Annex I: Glossary). {WGI SPM footnote 21&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-044-backlink|113]] The best estimates [and ''very likely'' ranges] for the different scenarios are: 1.4 [1.0 to 1.8]°C (SSP1-1.9); 1.8 [1.3 to 2.4]°C (SSP1-2.6); 2.7 [2.1 to 3.5]°C (SSP2-4.5); 3.6 [2.8 to 4.6]°C (SSP3-7.0); and 4.4 [3.3 to 5.7]°C (SSP5-8.5). {WGI Table SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} . ( Cross-Section Box.2 )

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

[[#footnote-043-backlink|114]] In the near term (2021 – 2040), the 1.5°C global warming level is ''very likely'' to be exceeded under the very high GHG emissions scenario (SSP5-8.5), ''likely'' to be exceeded under the intermediate and high GHG emissions scenarios (SSP2-4.5, SSP3-7.0), ''more likely than not'' to be exceeded under the low GHG emissions scenario (SSP1-2.6) and ''more likely than not'' to be reached under the very low GHG emissions scenario (SSP1-1.9). In all scenarios considered by WGI except the very high emissions scenario, the midpoint of the first 20-year running average period during which the assessed global warming reaches 1.5°C lies in the first half of the 2030s. In the very high GHG emissions scenario, this mid-point is in the late 2020s. The median five-year interval at which a 1.5°C global warming level is reached (50% probability) in categories of modelled pathways considered in WGIII is 2030 – 2035. {WGI SPM B.1.3, WGI Cross-Section Box TS.1, WGIII Table 3.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} . ( Cross-Section Box.2 )

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

[[#footnote-042-backlink|115]] See Cross-Section Box.2.

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

[[#footnote-041-backlink|116]] Based on additional scenarios.

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

[[#footnote-040-backlink|117]] Particularly over South and South East Asia, East Asia and West Africa apart from the far west Sahel. {WGI SPM B.3.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-039-backlink|118]] See Annex I: Glossary.

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

[[#footnote-038-backlink|119]] See Annex I: Glossary.

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

[[#footnote-037-backlink|120]] Undetectable risk level indicates no associated impacts are detectable and attributable to climate change; moderate risk indicates associated impacts are both detectable and attributable to climate change with at least ''medium confidence'' , also accounting for the other specific criteria for key risks; high risk indicates severe and widespread impacts that are judged to be high on one or more criteria for assessing key risks; and very high risk level indicates very high risk of severe impacts and the presence of significant irreversibility or the persistence of climate-related hazards, combined with limited ability to adapt due to the nature of the hazard or impacts/risks. {WGII Figure SPM.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-036-backlink|121]] The Reasons for Concern (RFC) framework communicates scientific understanding about accrual of risk for five broad categories (WGII Figure SPM.3). RFC1: Unique and threatened systems: ecological and human systems that have restricted geographic ranges constrained by climate-related conditions and have high endemism or other distinctive properties. Examples include coral reefs, the Arctic and its Indigenous Peoples, mountain glaciers and biodiversity hotspots. RFC2: Extreme weather events: risks/impacts to human health, livelihoods, assets and ecosystems from extreme weather events such as heatwaves, heavy rain, drought and associated wildfires, and coastal flooding. RFC3: Distribution of impacts: risks/impacts that disproportionately affect particular groups due to uneven distribution of physical climate change hazards, exposure or vulnerability. RFC4: Global aggregate impacts: impacts to socio-ecological systems that can be aggregated globally into a single metric, such as monetary damages, lives affected, species lost or ecosystem degradation at a global scale. RFC5: Large-scale singular events: relatively large, abrupt and sometimes irreversible changes in systems caused by global warming, such as ice sheet instability or thermohaline circulation slowing. Assessment methods include a structured expert elicitation based on the literature described in WGII SM16.6 and are identical to AR5 but are enhanced by a structured approach to improve robustness and facilitate comparison between AR5 and AR6. For further explanations of global risk levels and Reasons for Concern, see WGII TS.AII. {WGII Figure SPM.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-035-backlink|122]] Several SRM approaches have been proposed, including stratospheric aerosol injection, marine cloud brightening, ground-based albedo modifications, and ocean albedo change. See Annex I: Glossary.

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

[[#footnote-034-backlink|123]] This outcome is characterised by deep uncertainty: Its likelihood defies quantitative assessment but is considered due to its high potential impact. {WGI Box TS.1; WGII Cross-Chapter Box DEEP&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-033-backlink|124]] See Annex I: Glossary. Examples of compound extreme events are concurrent heatwaves and droughts or compound flooding. {WGI SPM Footnote 18}

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

[[#footnote-032-backlink|125]] 124 See Annex I: Glossary. Examples of compound extreme events are concurrent heatwaves and droughts or compound flooding. {WGI SPM Footnote 18&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

There are limitations to assessing the full scope of adaptation options available in the future since not all possible future adaptation responses can be incorporated in climate impact models, and projections of future adaptation depend on currently available technologies or approaches. {WGII 4.7.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-031-backlink|126]] See Annex I: Glossary.

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

[[#footnote-030-backlink|127]] This likelihood is based on the uncertainty in transient climate response to cumulative net CO 2 emissions and additional Earth system feedbacks and provides the probability that global warming will not exceed the temperature levels specified. {WGI Table SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-029-backlink|128]] Global databases make different choices about which emissions and removals occurring on land are considered anthropogenic. Most countries report their anthropogenic land CO 2 fluxes including fluxes due to human-caused environmental change (e.g., CO 2 fertilisation) on ‘managed’ land in their National GHG inventories. Using emissions estimates based on these inventories, the remaining carbon budgets must be correspondingly reduced. {WGIII SPM Footnote 9, WGIII TS.3, WGIII Cross-Chapter Box 6&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-028-backlink|129]] The central case RCB assumes future non-CO 2 warming (the net additional contribution of aerosols and non-CO 2 GHG) of around 0.1°C above 2010 – 2019 in line with stringent mitigation scenarios. If additional non-CO 2 warming is higher, the RCB for limiting warming to 1.5°C with a 50% likelihood shrinks to around 300 GtCO 2 . If, however, additional non-CO 2 warming is limited to only 0.05°C (via stronger reductions of CH 4 and N 2 O through a combination of deep structural and behavioural changes, e.g., dietary changes), the RCB could be around 600 GtCO 2 for 1.5°C warming. {WGI Table SPM.2, WGI Box TS.7; WGIII Box 3.4&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-027-backlink|130]] When adjusted for emissions since previous reports, these RCB estimates are similar to SR1.5 but larger than AR5 values due to methodological improvements.. {WGI SPM D.1.3&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-026-backlink|131]] Uncertainties for total carbon budgets have not been assessed and could affect the specific calculated fractions.

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

[[#footnote-025-backlink|132]] See footnote 131.

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

[[#footnote-024-backlink|133]] These projected adjustments of carbon sinks to stabilisation or decline of atmospheric CO 2 concentrations are accounted for in calculations of remaining carbon budgets. {WGI SPM footnote 32&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-023-backlink|134]] Net zero GHG emissions defined by the 100-year global warming potential. See footnote 70.

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

[[#footnote-022-backlink|135]] See Section 3.3.3 and 3.4.1.

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

[[#footnote-021-backlink|136]] CCS is an option to reduce emissions from large-scale fossil-based energy and industry sources provided geological storage is available. When CO 2 is captured directly from the atmosphere (DACCS), or from biomass (BECCS), CCS provides the storage component of these CDR methods. CO 2 capture and subsurface injection is a mature technology for gas processing and enhanced oil recovery. In contrast to the oil and gas sector, CCS is less mature in the power sector, as well as in cement and chemicals production, where it is a critical mitigation option. The technical geological storage capacity is estimated to be on the order of 1000 GtCO 2 , which is more than the CO 2 storage requirements through 2100 to limit global warming to 1.5°C, although the regional availability of geological storage could be a limiting factor. If the geological storage site is appropriately selected and managed, it is estimated that the CO 2 can be permanently isolated from the atmosphere. Implementation of CCS currently faces technological, economic, institutional, ecological environmental and socio-cultural barriers. Currently, global rates of CCS deployment are far below those in modelled pathways limiting global warming to 1.5°C to 2°C. Enabling conditions such as policy instruments, greater public support and technological innovation could reduce these barriers. ''(high confidence)'' {WGIII SPM C.4.6&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-020-backlink|137]] Limited overshoot refers to exceeding 1.5°C global warming by up to about 0.1°C, high overshoot by 0.1°C to 0.3°C, in both cases for up to several decades. {WGIII Box SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-019-backlink|138]] See Annex I: Glossary.

139 The impacts, risks, and co-benefits of CDR deployment for ecosystems, biodiversity and people will be highly variable depending on the method, site-specific context, implementation and scale (high confidence ) . {WGIII SPM C.11.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

140 The evidence is too limited to make a similar robust conclusion for limiting warming to 1.5°C. {WGIII SPM footnote 68}

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

[[#footnote-018-backlink|139]] The impacts, risks, and co-benefits of CDR deployment for ecosystems, biodiversity and people will be highly variable depending on the method, site-specific context, implementation and scale ''(high confidence).'' {WGIII SPM C.11.2}

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

[[#footnote-017-backlink|140]] The evidence is too limited to make a simil a r robust conclusion for limiting warming to 1.5°C. {WGIII SPM footnote 68}

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

[[#footnote-016-backlink|141]] In the near term (2021 – 2040), the 1.5°C global warming level is very ''likely'' to be exceeded under the very high GHG emissions scenario (SSP5-8.5), ''likely'' to be exceeded under the intermediate and high GHG emissions scenarios (SSP2-4.5, SSP3-7.0), ''more likely than not'' to be exceeded under the low GHG emissions scenario (SSP1-2.6) and ''more likely than not'' to be reached under the very low GHG emissions scenario (SSP1-1.9). The best estimates [and ''very likely'' ranges] of global warming for the different scenarios in the near term are: 1.5 [1.2 to 1.7]°C (SSP1-1.9); 1.5 [1.2 to 1.8]°C (SSP1-2.6); 1.5 [1.2 to 1.8]°C (SSP2-4.5); 1.5 [1.2 to 1.8]°C (SSP3-7.0); and 1.6[1.3 to 1.9]°C (SSP5-8.5). {WGI SPM B.1.3, WGI Table SPM.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;} ( Cross-Section Box.2 )

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

[[#footnote-015-backlink|142]] Values in parentheses indicate the likelihood of limiting warming to the level specified (see Cross-Section Box.2).

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

[[#footnote-014-backlink|143]] Median and very ''likely'' range [5th to 95th percentile]. {WGIII SPM footnote 30&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-013-backlink|144]] These numbers for CO 2 are 48 [36 to 69]% in 2030, 65 [50 to 96] % in 2035, 80 [61 to109] % in 2040 and 99 [79 to 119]% in 2050.

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

[[#footnote-012-backlink|145]] These numbers for CO 2 are 22 [1 to 44]% in 2030, 37 [21 to 59] % in 2035, 51 [36 to 70] % in 2040 and 73 [55 to 90]% in 2050.

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

[[#footnote-011-backlink|146]] 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 to 80% of fugitive methane emissions from energy supply. {WGIII SPM footnote 54&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-010-backlink|147]] The southern part of Mexico is included in the climatic subregion South Central America (SCA) for WGI. Mexico is assessed as part of North America for WGII. The climate change literature for the SCA region occasionally includes Mexico, and in those cases WGII assessment makes reference to Latin America. Mexico is considered part of Latin America and the Caribbean for WGIII.. {WGII 12.1.1, WGIII AII.1.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-009-backlink|148]] 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 to 80% of fugitive methane emissions from energy supply. {WGIII SPM footnote 54&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-008-backlink|149]] See Annex I: Glossary. The main internal variability phenomena include El Niño–Southern Oscillation, Pacific Decadal Variability and Atlantic Multi-decadal Variability through their regional influence. The internal variability of global surface temperature in any single year is estimated to be about ±0.25°C (5 to 95% range, ''high confidence).'' {WGI SPM footnote 29, WGI SPM footnote 37&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-007-backlink|150]] Based on 2500-year reconstructions, eruptions with a radiative forcing more negative than –1 Wm ''-2'' , related to the radiative effect of volcanic stratospheric aerosols in the literature assessed in this report, occur on average twice per century. {WGI SPM footnote 38&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-006-backlink|151]] System transitions involve a wide portfolio of mitigation and adaptation options that enable deep emissions reductions and transformative adaptation in all sectors. This report has a particular focus on the following system transitions: energy; industry; cities, settlements and infrastructure; land, ocean, food and water; health and nutrition; and society, livelihood and economies.. {WGII SPM A, WGII Figure SPM.1, WGII Figure SPM.4; SR1.5 SPM C.2&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-005-backlink|152]] See Annex I: Glossary.

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

[[#footnote-004-backlink|153]] 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. {WGIII SPM footnote 54&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-003-backlink|154]] The mitigation potentials and mitigation costs of individual technologies in a specific context or region may differ greatly from the provided estimates (medium confidence ). {WGIII SPM C.12.1&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}

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

[[#footnote-002-backlink|155]] 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. ''{WGIII Annex I&lt;/span&gt;&lt;span class=&quot;CharOverride-27&quot;&gt;}''

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

[[#footnote-001-backlink|156]] Balanced diets refer 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-000" class="_idFootnote"></div>

[[#footnote-000-backlink|157]] Finance can originate from diverse sources, singly or in combination: public or private, local, national or international, bilateral or multilateral, and alternative sources (e.g., philanthropic, carbon offsets). It can be in the form of grants, technical assistance, loans (concessional and non-concessional), bonds, equity, risk insurance and financial guarantees (of various types).