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Climate Change 2023

Synthesis Report

IPCC, 2023: Sections. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth

Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, H. Lee and J. Romero (eds.)]. IPCC,

Geneva, Switzerland, pp. 35-115, doi: 10.59327/IPCC/AR6-9789291691647

These Sections should be cited as:

Section 1

Introduction

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ClimateChange2023SynthesisReportTheseSectionsshouldbecitedas:IPCC,2023:Sections.In:ClimateChange2023:SynthesisReport.ContributionofWorkingGroupsI,IIandIIItotheSixthAssessmentReportoftheIntergovernmentalPanelonClimateChange[CoreWritingTeam,H.LeeandJ.Romero(eds.)].IPCC,Geneva,Switzerland,pp.35-115,doi:10.59327/IPCC/AR6-978929169164735Section1Introduction37Section11.IntroductionThisSynthesisReport(SYR)oftheIPCCSixthAssessmentReport(AR6)futures.Itconsiderslong-termcharacteristics,impacts,risksandcostssummarisesthestateofknowledgeofclimatechange,itswidespreadinadaptationandmitigationpathwaysinthecontextofsustainableimpactsandrisks,andclimatechangemitigationandadaptation,baseddevelopment.Section4,‘Near-TermResponsesinaChangingClimate’,onthepeer-reviewedscientiﬁc,technicalandsocio-economicliteratureassessesopportunitiesforscalingupeffectiveactionintheperiodupsincethepublicationoftheIPCC’sFifthAssessmentReport(AR5)into2040,inthecontextofclimatepledges,andcommitments,andthe2014.pursuitofsustainabledevelopment.TheassessmentisundertakenwithinthecontextoftheevolvingBasedonscientiﬁcunderstanding,keyﬁndingscanbeformulatedasinternationallandscape,inparticular,developmentsintheUNstatementsoffactorassociatedwithanassessedlevelofconﬁdenceFrameworkConventiononClimateChange(UNFCCC)process,usingtheIPCCcalibratedlanguage62.ThescientiﬁcﬁndingsareincludingtheoutcomesoftheKyotoProtocolandtheadoptionofthedrawnfromtheunderlyingreportsandarisefromtheirSummaryforParisAgreement.ItreﬂectstheincreasingdiversityofthoseinvolvedinPolicymakers(hereafterSPM),TechnicalSummary(hereafterTS),andclimateaction.underlyingchaptersandareindicatedby{}brackets.Figure1.1showstheSynthesisReportFiguresKey,aguidetovisualiconsthatareusedThisreportintegratesthemainﬁndingsoftheAR6WorkingGroupacrossmultipleﬁgureswithinthisreport.reports58andthethreeAR6SpecialReports59.Itrecognizestheinterdependenceofclimate,ecosystemsandbiodiversity,andhumansocieties;thevalueofdiverseformsofknowledge;andthecloselinkagesbetweenclimatechangeadaptation,mitigation,ecosystemhealth,humanwell-beingandsustainabledevelopment.Buildingonmultipleanalyticalframeworks,includingthosefromthephysicalandsocialsciences,thisreportidentiﬁesopportunitiesfortransformativeactionwhichareeffective,feasible,justandequitableusingconceptsofsystemstransitionsandresilientdevelopmentpathways60.Differentregionalclassiﬁcationschemes61areusedforphysical,socialandeconomicaspects,reﬂectingtheunderlyingliterature.Section1Afterthisintroduction,Section2,‘CurrentStatusandTrends’,openswiththeassessmentofobservationalevidenceforourchangingclimate,historicalandcurrentdriversofhuman-inducedclimatechange,anditsimpacts.Itassessesthecurrentimplementationofadaptationandmitigationresponseoptions.Section3,‘Long-TermClimateandDevelopmentFutures’,providesalong-termassessmentofclimatechangeto2100andbeyondinabroadrangeofsocio-economic58ThethreeWorkingGroupcontributionstoAR6are:ClimateChange2021:ThePhysicalScienceBasis;ClimateChange2022:Impacts,AdaptationandVulnerability;andClimateChange2022:MitigationofClimateChange,respectively.Theirassessmentscoverscientiﬁcliteratureacceptedforpublicationrespectivelyby31January2021,1September2021and11October2021.59ThethreeSpecialReportsare:GlobalWarmingof1.5°C(2018):anIPCCSpecialReportontheimpactsofglobalwarmingof1.5°Cabovepre-industriallevelsandrelatedglobalgreenhousegasemissionpathways,inthecontextofstrengtheningtheglobalresponsetothethreatofclimatechange,sustainabledevelopment,andeffortstoeradicatepoverty(SR1.5);ClimateChangeandLand(2019):anIPCCSpecialReportonclimatechange,desertiﬁcation,landdegradation,sustainablelandmanagement,foodsecurity,andgreenhousegasﬂuxesinterrestrialecosystems(SRCCL);andTheOceanandCryosphereinaChangingClimate(2019)(SROCC).TheSpecialReportscoverscientiﬁcliteratureacceptedforpublicationrespectivelyby15May2018,7April2019and15May2019.60TheGlossary(AnnexI)includesdeﬁnitionsofthese,andothertermsandconceptsusedinthisreportdrawnfromtheAR6jointWorkingGroupGlossary.61Dependingontheclimateinformationcontext,geographicalregionsinAR6mayrefertolargerareas,suchassub-continentsandoceanicregions,ortotypologicalregions,suchasmonsoonregions,coastlines,mountainrangesorcities.AnewsetofstandardAR6WGIreferencelandandoceanregionshavebeendeﬁned.WGIIIallocatescountriestogeographicalregions,basedontheUNStatisticsDivisionClassiﬁcation{WGI1.4.5,WGI10.1,WGI11.9,WGI12.1–12.4,WGIAtlas.1.3.3–1.3.4}.62Eachﬁndingisgroundedinanevaluationofunderlyingevidenceandagreement.Alevelofconﬁdenceisexpressedusingﬁvequaliﬁers:verylow,low,medium,highandveryhigh,andtypesetinitalics,forexample,mediumconﬁdence.Thefollowingtermshavebeenusedtoindicatetheassessedlikelihoodofanoutcomeorresult:virtuallycertain99–100%probability;verylikely90–100%;likely66–100%;morelikelythannot>50-100%;aboutaslikelyasnot33–66%;unlikely0–33%;veryunlikely0–10%;andexceptionallyunlikely0–1%.Additionalterms(extremelylikely95–100%andextremelyunlikely0–5%)arealsousedwhenappropriate.Assessedlikelihoodalsoistypesetinitalics:forexample,verylikely.ThisisconsistentwithAR5.InthisReport,unlessstatedotherwise,squarebrackets[xtoy]areusedtoprovidetheassessedverylikelyrange,or90%interval.38IntroductionSynthesisReportAxislabelsthesehelpnon-expertsItalicized‘annotations’ﬁgureskeyGHGemissionsnavigatecomplexcontentSimpleexplanationswritteninnon-technicallanguage°CTemperatureCostorbudgetnetzeroNetzeroFigure1.1:TheSynthesisReportﬁgureskey.Section13940Section2CurrentStatusandTrends41Section2Section2:CurrentStatusandTrends2.1ObservedChanges,ImpactsandAttributionHumanactivities,principallythroughemissionsofgreenhousegases,haveunequivocallycausedglobalwarming,withglobalsurfacetemperaturereaching1.1°Cabove1850–1900in2011–2020.Globalgreenhousegasemissionshavecontinuedtoincreaseover2010–2019,withunequalhistoricalandongoingcontributionsarisingfromunsustainableenergyuse,landuseandland-usechange,lifestylesandpatternsofconsumptionandproductionacrossregions,betweenandwithincountries,andbetweenindividuals(highconﬁdence).Human-causedclimatechangeisalreadyaffectingmanyweatherandclimateextremesineveryregionacrosstheglobe.Thishasledtowidespreadadverseimpactsonfoodandwatersecurity,humanhealthandoneconomiesandsocietyandrelatedlossesanddamages63tonatureandpeople(highconﬁdence).Vulnerablecommunitieswhohavehistoricallycontributedtheleasttocurrentclimatechangearedisproportionatelyaffected(highconﬁdence).623.1.I1n.thOisbrespeorrt,vtehedteWrma‘lromsseisnagndadnamdagitess’rCefaerusstoeasdverseobservedimpactsand/orprojectedrisksandcanbeeconomicand/ornon-economic.(SeeAnnexI:Glossary)thepastsixdecades,withregionaldifferences(highconﬁdence).In2019,Globalsurfacetemperaturewasaround1.1°Cabove1850–1900inatmosphericCO2concentrationsreached410partspermillion(ppm),CH42011–2020(1.09[0.95to1.20]°C)64,withlargerincreasesreached1866partsperbillion(ppb)andnitrousoxide(N2O)reached332ppb68.overland(1.59[1.34to1.83]°C)thanovertheoceanOthermajorcontributorstowarmingaretroposphericozone(O3)and(0.88[0.68to1.01]°C)65.Observedwarmingishuman-caused,withhalogenatedgases.ConcentrationsofCH4andN2Ohaveincreasedtowarmingfromgreenhousegases(GHG),dominatedbyCO2andlevelsunprecedentedinatleast800,000years(veryhighconﬁdence),methane(CH4),partlymaskedbyaerosolcooling(Figure2.1).andthereishighconﬁdencethatcurrentCO2concentrationsareGlobalsurfacetemperatureintheﬁrsttwodecadesofthe21stcenturyhigherthanatanytimeoveratleastthepasttwomillionyears.Since1750,increasesinCO2(47%)andCH4(156%)concentrationsfar(2001–2020)was0.99[0.84to1.10]°Chigherthan1850–1900.Globalexceed–andincreasesinN2O(23%)aresimilarto–thenaturalsurfacetemperaturehasincreasedfastersince1970thaninanyothermulti-millennialchangesbetweenglacialandinterglacialperiodsoveratleastthepast800,000years(veryhighconﬁdence).Thenetcoolingeffect50-yearperiodoveratleastthelast2000years(highconﬁdence).Thewhicharisesfromanthropogenicaerosolspeakedinthelate20thcenturylikelyrangeoftotalhuman-causedglobalsurfacetemperatureincrease(highconﬁdence).{WGISPMA1.1,WGISPMA1.3,WGISPMA.2.1,from1850–1900to2010–201966is0.8°Cto1.3°C,withabestestimateWGIFigureSPM.2,WGITS2.2,WGI2ES,WGIFigure6.1}of1.07°C.Itislikelythatwell-mixedGHGs67contributedawarmingof1.0°Cto2.0°C,andotherhumandrivers(principallyaerosols)SectioSnec2tion1contributedacoolingof0.0°Cto0.8°C,natural(solarandvolcanic)driverschangedglobalsurfacetemperatureby±0.1°Candinternalvariabilitychangeditby±0.2°C.{WGISPMA.1,WGISPMA.1.2,WGISPMA.1.3,WGISPMA.2.2,WGIFigureSPM.2;SRCCLTS.2}Observedincreasesinwell-mixedGHGconcentrationssincearound1750areunequivocallycausedbyGHGemissionsfromhumanactivities.Landandoceansinkshavetakenupanear-constantproportion(globallyabout56%peryear)ofCO2emissionsfromhumanactivitiesover63Inthisreport,theterm‘lossesanddamages’referstoadverseobservedimpactsand/orprojectedrisksandcanbeeconomicand/ornon-economic.(SeeAnnexI:Glossary)64TheestimatedincreaseinglobalsurfacetemperaturesinceAR5isprincipallyduetofurtherwarmingsince2003–2012(+0.19[0.16to0.22]°C).Additionally,methodologicaladvancesandnewdatasetshaveprovidedamorecompletespatialrepresentationofchangesinsurfacetemperature,includingintheArctic.Theseandotherimprovementshavealsoincreasedtheestimateofglobalsurfacetemperaturechangebyapproximately0.1°C,butthisincreasedoesnotrepresentadditionalphysicalwarmingsinceAR5{WGISPMA1.2andfootnote10}65For1850–1900to2013–2022theupdatedcalculationsare1.15[1.00to1.25]°Cforglobalsurfacetemperature,1.65[1.36to1.90]°Cforlandtemperaturesand0.93[0.73to1.04]°Cforoceantemperaturesabove1850–1900usingtheexactsamedatasets(updatedby2years)andmethodsasemployedinWGI.66Theperioddistinctionwiththeobservedassessmentarisesbecausetheattributionstudiesconsiderthisslightlyearlierperiod.Theobservedwarmingto2010–2019is1.06[0.88to1.21]°C.{WGISPMfootnote11}67Contributionsfromemissionstothe2010–2019warmingrelativeto1850–1900assessedfromradiativeforcingstudiesare:CO20.8[0.5to1.2]°C;methane0.5[0.3to0.8]°C;nitrousoxide0.1[0.0to0.2]°Candﬂuorinatedgases0.1[0.0to0.2]°C.68For2021(themostrecentyearforwhichﬁnalnumbersareavailable)concentrationsusingthesameobservationalproductsandmethodsasinAR6WGIare:415ppmCO2;1896ppbCH4;and335ppbN2O.NotethattheCO2isreportedhereusingtheWMO-CO2-X2007scaletobeconsistentwithWGI.OperationalCO2reportinghassincebeenupdatedtousetheWMO-CO2-X2019scale.42CurrentStatusandTrendsHumanactivitiesareresponsibleforglobalwarmingc)Changesinglobalsurfacetemperatured)HumansareresponsibleGlobalsurfacetemperaturehasincreasedbyObservedwarmingisdrivenbyemissions1.1°Cby2011-2020comparedto1850-1900fromhumanactivitieswithGHGwarming°C2.0partlymaskedbyaerosolcooling2010–2019(changefrom1850–1900)1.52.0°C1.01.01.50.5Observed1.00.20.0warmest0.50.0–0.5–1.0multi-centuryObservedwarming–0.5periodinmoreTotalhumaninﬂuencethan100,000–1.0yearsWell-mixedGHGOtherhumandrivers18501900195020002020SolarandvolcanicdriversKeyInternalvariability°C00.511.5b)ConcentrationsofGHGshaveincreasedrapidlysince1850Otherhumandriversarepredominantlycoolingaerosols,butalsowarmingaerosols,land-usechange(land-usereﬂectance)andozone.Increasedconcentrations(scaledtomatchtheirassessedcontributionstowarmingover1850–1900Figure2.1:ThecausalchainfromemissionstoresultingofGHGsintheatmosphereto2010–2019)400Partspermillion(ppm)410ppmCO2warmingoftheclimatesystem.EmissionsofGHGhaveincreasedrapidlyoverrecentdecades(panel(a)).GlobalnetanthropogenicGHGemissionsincludeCO2fromfossilfuel350combustionandindustrialprocesses(CO2-FFI)(darkgreen);CarbondioxidenetCO2fromlanduse,land-usechangeandforestry(CO2-LULUCF)Section2(green);CH4;N2O;andﬂuorinatedgases(HFCs,PFCs,SF6,NF3)300(lightblue).TheseemissionshaveledtoincreasesintheatmosphericPartsperbillion(ppb)1866ppbCH4concentrationsofseveralGHGsincludingthethreemajorwell-mixed1500GHGsCO2,CH4andN2O(panel(b),annualvalues).Toindicatetheir1000Methanerelativeimportanceeachsubpanel’sverticalextentforCO2,CH4andN2Oisscaledtomatchtheassessedindividualdirecteffect(and,inthecaseofCH4indirecteffectviaatmosphericchemistryimpacts500ontroposphericozone)ofhistoricalemissionsontemperature400Partsperbillion(ppb)Nitrousoxide332ppbN2Ochangefrom1850–1900to2010–2019.Thisestimatearisesfromanassessmentofeffectiveradiativeforcingandclimatesensitivity.200Theglobalsurfacetemperature(shownasannualanomaliesfrom18501900195020002019a1850–1900baseline)hasincreasedbyaround1.1°Csince1850–1900(panel(c)).Theverticalbarontherightshowsthea)estimatedtemperature(verylikelyrange)duringthewarmestmulti-centuryperiodinatleastthelast100,000years,whichGreenhousegas(GHG)emissionsresultingIncreasedemissionsoffromhumanactivitiescontinuetoincreaseoccurredaround6500yearsagoduringthecurrentinterglacialgreenhousegases(GHGs)60period(Holocene).Priortothat,thenextmostrecentwarmperiodGHGEmissions(GtCO2-eq/yr)Non-CO2wasabout125,000yearsago,whentheassessedmulti-centuryemissionstemperaturerange[0.5°Cto1.5°C]overlapstheobservationsof45CO2fromLandthemostrecentdecade.Thesepastwarmperiodswerecausedbyslow(multi-millennial)orbitalvariations.FormaldetectionandUse,Land-UseattributionstudiessynthesiseinformationfromclimatemodelsChangeandForestryandobservationsandshowthatthebestestimateisthatallthe30(LULUCF)warmingobservedbetween1850–1900and2010–2019iscausedbyhumans(panel(d)).Thepanelshowstemperaturechange15CO2fromattributedto:totalhumaninﬂuence;itsdecompositionintochangesfossilfuelsinGHGconcentrationsandotherhumandrivers(aerosols,ozoneandindustryandland-usechange(land-usereﬂectance));solarandvolcanicdrivers;andinternalclimatevariability.Whiskersshowlikelyranges.0{WGISPMA.2.2,WGIFigureSPM.1,WGIFigureSPM.2,WGITS2.2,18501900195020002019WGI2.1;WGIIIFigureSPM.1,WGIIIA.III.II.2.5.1}43Section2AverageannualGHGemissionsduring2010–2019werehigher2010and2019slowedcomparedtothepreviousdecadeinenergythaninanypreviousdecade,buttherateofgrowthbetweensupply(from2.3%to1.0%)andindustry(from3.4%to1.4%)but2010and2019(1.3%yr-1)waslowerthanthatbetween2000remainedroughlyconstantatabout2%yr–1inthetransportsectorand2009(2.1%yr-1)69.HistoricalcumulativenetCO2emissionsfrom(highconﬁdence).AbouthalfoftotalnetAFOLUemissionsarefrom1850to2019were2400±240GtCO2.Ofthese,morethanhalf(58%)CO2LULUCF,predominantlyfromdeforestation(mediumconﬁdence).occurredbetween1850and1989[1400±195GtCO2],andabout42%Landoverallconstitutedanetsinkof–6.6(±4.6)GtCO2yr–1fortheperiodbetween1990and2019[1000±90GtCO2].Globalnetanthropogenic2010–201972(mediumconﬁdence).{WGIIISPMB.2,WGIIISPMB.2.1,GHGemissionshavebeenestimatedtobe59±6.6GtCO2-eqin2019,WGIIISPMB.2.2,WGIIITS5.6.1}about12%(6.5GtCO2-eq)higherthanin2010and54%(21GtCO2-eq)higherthanin1990.By2019,thelargestgrowthingrossemissionsHuman-causedclimatechangeisaconsequenceofmorethanoccurredinCO2fromfossilfuelsandindustry(CO2-FFI)followedbyacenturyofnetGHGemissionsfromenergyuse,land-useandCH4,whereasthehighestrelativegrowthoccurredinfluorinatedlandusechange,lifestyleandpatternsofconsumption,andgases(F-gases),startingfromlowlevelsin1990.(highconfidence)production.EmissionsreductionsinCO2fromfossilfuelsandindustrial{WGIIISPMB1.1,WGIIISPMB.1.2,WGIIISPMB.1.3,WGIIIFigureSPM.1,processes(CO2-FFI),duetoimprovementsinenergyintensityofGDPWGIIIFigureSPM.2}andcarbonintensityofenergy,havebeenlessthanemissionsincreasesfromrisingglobalactivitylevelsinindustry,energysupply,transport,Regionalcontributionstoglobalhuman-causedGHGemissionsagricultureandbuildings.The10%ofhouseholdswiththehighestpercontinuetodifferwidely.HistoricalcontributionsofCO2emissionscapitaemissionscontribute34–45%ofglobalconsumption-basedvarysubstantiallyacrossregionsintermsoftotalmagnitude,butalsohouseholdGHGemissions,whilethemiddle40%contribute40–53%,intermsofcontributionstoCO2-FFI(1650±73GtCO2-eq)andnetandthebottom50%contribute13–15%.AnincreasingshareofCO2-LULUCF(760±220GtCO2-eq)emissions(Figure2.2).Variationsemissionscanbeattributedtourbanareas(arisefromabout62%inregionalandnationalpercapitaemissionspartlyreﬂectdifferentto67–72%oftheglobalsharebetween2015and2020).Thedriversdevelopmentstages,buttheyalsovarywidelyatsimilarincomeofurbanGHGemissions73arecomplexandincludepopulationsize,levels.AveragepercapitanetanthropogenicGHGemissionsin2019income,stateofurbanisationandurbanform.(highconﬁdence)rangedfrom2.6tCO2-eqto19tCO2-eqacrossregions(Figure2.2).{WGIIISPMB.2,WGIIISPMB.2.3,WGIIISPMB.3.4,WGIIISPMD.1.1}LeastDevelopedCountries(LDCs)andSmallIslandDevelopingStates(SIDS)SectioSnec2tion1havemuchlowerpercapitaemissions(1.7tCO2-eqand4.6tCO2-eq,respectively)thantheglobalaverage(6.9tCO2-eq),excludingCO2-LULUCF.Around48%oftheglobalpopulationin2019livesincountriesemittingonaveragemorethan6tCO2-eqpercapita,35%oftheglobalpopulationliveincountriesemittingmorethan9tCO2-eqpercapita70(excludingCO2-LULUCF)whileanother41%liveincountriesemittinglessthan3tCO2-eqpercapita.Asubstantialshareofthepopulationintheselow-emittingcountrieslackaccesstomodernenergyservices.(highconﬁdence){WGIIISPMB.3,WGIIISPMB3.1,WGIIISPMB.3.2,WGIIISPMB.3.3}NetGHGemissionshaveincreasedsince2010acrossallmajorsectors(highconﬁdence).In2019,approximately34%(20GtCO2-eq)ofnetglobalGHGemissionscamefromtheenergysector,24%(14GtCO2-eq)fromindustry,22%(13GtCO2-eq)fromAFOLU,15%(8.7GtCO2-eq)fromtransportand6%(3.3GtCO2-eq)frombuildings71(highconﬁdence).AverageannualGHGemissionsgrowthbetween69GHGemissionmetricsareusedtoexpressemissionsofdifferentGHGsinacommonunit.AggregatedGHGemissionsinthisreportarestatedinCO2-equivalents(CO2-eq)usingtheGlobalWarmingPotentialwithatimehorizonof100years(GWP100)withvaluesbasedonthecontributionofWorkingGroupItotheAR6.TheAR6WGIandWGIIIreportscontainupdatedemissionmetricvalues,evaluationsofdifferentmetricswithregardtomitigationobjectives,andassessnewapproachestoaggregatinggases.ThechoiceofmetricdependsonthepurposeoftheanalysisandallGHGemissionmetricshavelimitationsanduncertainties,giventhattheysimplifythecomplexityofthephysicalclimatesystemanditsresponsetopastandfutureGHGemissions.{WGISPMD.1.8,WGI7.6;WGIIISPMB.1,WGIIICross-ChapterBox2.2}(AnnexI:Glossary)70Territorialemissions71GHGemissionlevelsareroundedtotwosigniﬁcantdigits;asaconsequence,smalldifferencesinsumsduetoroundingmayoccur.{WGIIISPMfootnote8}72Comprisingagrosssinkof-12.5(±3.2)GtCO2yr-1resultingfromresponsesofalllandtobothanthropogenicenvironmentalchangeandnaturalclimatevariability,andnetanthropogenicCO2-LULUCFemissions+5.9(±4.1)GtCO2yr-1basedonbook-keepingmodels.{WGIIISPMFootnote14}73Thisestimateisbasedonconsumption-basedaccounting,includingbothdirectemissionsfromwithinurbanareas,andindirectemissionsfromoutsideurbanareasrelatedtotheproductionofelectricity,goodsandservicesconsumedincities.TheseestimatesincludeallCO2andCH4emissioncategoriesexceptforaviationandmarinebunkerfuels,land-usechange,forestryandagriculture.{WGIIISPMfootnote15}44CurrentStatusandTrendsEmissionshavegrowninmostregionsbutaredistributedunevenly,bothinthepresentdayandcumulativelysince1850a)Historicalcumulativenetanthropogenicb)NetanthropogenicGHGemissionspercapitaCO2emissionsperregion(1850–2019)andfortotalpopulation,perregion(2019)CO2GHGNorthAmericaNorthAmerica20Australia,JapanandNewZealandEuropeEasternAsia/GHGemissions(tCO2-eqpercapita)EasternEuropeandWest-CentralAsia60023%LatinAmericaandCaribbean15MiddleEastEasternEuropeandWest-CentralAsiaCO2emissions(GtCO2)South-EastAsiaandPaciﬁcEasternAsiaAfricaLatinAmericaandCaribbean40016%Australia,JapanandNewZealand10Europe12%11%10%SouthernAsiaSouth-EastAsiaandPaciﬁcMiddleEast2008%7%International5AfricashippingandaviationSouthernAsia4%4%2%2%0002000400060008000Population(millions)Key19902019NetCO2fromlanduse,landusechange,forestry(CO2LULUCF)TimeframesrepresentedinthesegraphsOtherGHGemissions1850Fossilfuelandindustry(CO2FFI)AllGHGemissionsc)GlobalnetanthropogenicGHGemissionsbyregion(1990–2019)GHG59GtCO2-eqGHGemissionsperyear(GtCO2-eq/yr)6042GtCO2-eq53GtCO2-eqSection22%Internationalshippingandaviation502%2%3%Australia,JapanandNewZealand5%4%5%MiddleEastTotal:4%5%6%EasternEuropeandWest-CentralAsia38GtCO2-eq8%7%8%Europe13%10%8%SouthernAsia2%8%8%9%Africa5%8%8%9%South-EastAsiaandPaciﬁc3%7%7%10%LatinAmericaandCaribbean3014%11%11%12%NorthAmerica16%7%19%14%27%EasternAsia207%7%16%24%201910%1018%20002010013%1990d)Regionalindicators(2019)andregionalproductionvsconsumptionaccounting(2018)AfricaAustralia,EasternEasternEuropeLatinMiddleNorthSouth-EastSouthernJapan,AsiaEurope,AmericaEastAmericaAsiaandAsiaNewWest-andPacicZealandCentralAsiaCaribbean18366.2Population(millionpersons,2019)129215714712916206462523666740.42GDPpercapita(USD1000PPP2017perperson)15.043172043152061122.6NetGHG20192(productionbasis)1.61.5GHGemissionsintensity(tCO2-eq/USD1000PPP2017)0.780.300.620.640.180.610.640.310.65GHGpercapita(tCO2-eqperperson)3.91311137.89.213197.9CO2FFI,2018,perpersonProduction-basedemissions(tCO2FFIperperson,basedon2018data)1.2108.49.26.52.88.7162.6Consumption-basedemissions(tCO2FFIperperson,basedon2018data)0.84116.76.27.82.87.6172.51GDPpercapitain2019inUSD2017currencypurchasingpowerbasis.Theregionalgroupingsusedinthisﬁgureareforstatistical2IncludesCO2FFI,CO2LULUCFandOtherGHGs,excludinginternationalaviationandshipping.purposesonlyandaredescribedinWGIIIAnnexII,PartI.45Section2Figure2.2:RegionalGHGemissions,andtheregionalproportionoftotalcumulativeproduction-basedCO2emissionsfrom1850to2019.Panel(a)showstheshareofhistoricalcumulativenetanthropogenicCO2emissionsperregionfrom1850to2019inGtCO2.ThisincludesCO2-FFIandCO2-LULUCF.OtherGHGemissionsarenotincluded.CO2-LULUCFemissionsaresubjecttohighuncertainties,reﬂectedbyaglobaluncertaintyestimateof±70%(90%conﬁdenceinterval).Panel(b)showsthedistributionofregionalGHGemissionsintonnesCO2-eqpercapitabyregionin2019.GHGemissionsarecategorisedinto:CO2-FFI;netCO2-LULUCF;andotherGHGemissions(CH4,N2O,ﬂuorinatedgases,expressedinCO2-equsingGWP100-AR6).Theheightofeachrectangleshowspercapitaemissions,thewidthshowsthepopulationoftheregion,sothattheareaoftherectanglesreferstothetotalemissionsforeachregion.Emissionsfrominternationalaviationandshippingarenotincluded.Inthecaseoftworegions,theareaforCO2-LULUCFisbelowtheaxis,indicatingnetCO2removalsratherthanemissions.Panel(c)showsglobalnetanthropogenicGHGemissionsbyregion(inGtCO2-eqyr–1(GWP100-AR6))forthetimeperiod1990–2019.PercentagevaluesrefertothecontributionofeachregiontototalGHGemissionsineachrespectivetimeperiod.Thesingle-yearpeakofemissionsin1997wasduetohigherCO2-LULUCFemissionsfromaforestandpeatﬁreeventinSouthEastAsia.RegionsareasgroupedinAnnexIIofWGIII.Panel(d)showspopulation,grossdomesticproduct(GDP)perperson,emissionindicatorsbyregionin2019fortotalGHGperperson,andtotalGHGemissionsintensity,togetherwithproduction-basedandconsumption-basedCO2-FFIdata,whichisassessedinthisreportupto2018.Consumption-basedemissionsareemissionsreleasedtotheatmosphereinordertogeneratethegoodsandservicesconsumedbyacertainentity(e.g.,region).Emissionsfrominternationalaviationandshippingarenotincluded.{WGIIIFigureSPM.2}SectioSnec2tion12.1.2.ObservedClimateSystemChangesandImpactstoinfrequencysincethe1980s(highconﬁdence),andhumaninﬂuenceDatehasverylikelycontributedtomostofthemsinceatleast2006.ThefrequencyandintensityofheavyprecipitationeventshaveincreasedItisunequivocalthathumaninﬂuencehaswarmedthesincethe1950sovermostlandareasforwhichobservationaldataatmosphere,oceanandland.Widespreadandrapidchangesinaresufﬁcientfortrendanalysis(highconﬁdence),andhuman-causedtheatmosphere,ocean,cryosphereandbiospherehaveoccurredclimatechangeislikelythemaindriver(Figure2.3).Human-caused(Table2.1).Thescaleofrecentchangesacrosstheclimatesystemasclimatechangehascontributedtoincreasesinagriculturalandecologicalawholeandthepresentstateofmanyaspectsoftheclimatesystemdroughtsinsomeregionsduetoincreasedlandevapotranspirationareunprecedentedovermanycenturiestomanythousandsofyears.It(mediumconﬁdence)(Figure2.3).ItislikelythattheglobalproportionisverylikelythatGHGemissionswerethemaindriver74oftroposphericofmajor(Category3–5)tropicalcycloneoccurrencehasincreasedoverwarmingandextremelylikelythathuman-causedstratosphericozonethelastfourdecades.{WGISPMA.3,WGISPMA3.1,WGISPMA3.2;depletionwasthemaindriverofstratosphericcoolingbetween1979WGISPMA3.4;SRCCLSPM.A.2.2;SROCCSPM.A.2}andthemid-1990s.Itisvirtuallycertainthattheglobalupperocean(0-700m)haswarmedsincethe1970sandextremelylikelythatClimatechangehascausedsubstantialdamages,andincreasinglyhumaninﬂuenceisthemaindriver.Oceanwarmingaccountedforirreversible75losses,interrestrial,freshwater,cryosphericand91%oftheheatingintheclimatesystem,withlandwarming,icelosscoastalandopenoceanecosystems(highconﬁdence).Theextentandatmosphericwarmingaccountingforabout5%,3%and1%,andmagnitudeofclimatechangeimpactsarelargerthanestimatedrespectively(highconﬁdence).Globalmeansealevelincreasedby0.20inpreviousassessments(highconﬁdence).Approximatelyhalfofthe[0.15to0.25]mbetween1901and2018.Theaveragerateofsealevelspeciesassessedgloballyhaveshiftedpolewardsor,onland,alsotorisewas1.3[0.6to2.1]mmyr-1between1901and1971,increasingtohigherelevations(veryhighconﬁdence).Biologicalresponsesincluding1.9[0.8to2.9]mmyr-1between1971and2006,andfurtherincreasingchangesingeographicplacementandshiftingseasonaltimingareoftento3.7[3.2to–4.2]mmyr-1between2006and2018(highconﬁdence).notsufﬁcienttocopewithrecentclimatechange(veryhighconﬁdence).HumaninﬂuencewasverylikelythemaindriveroftheseincreasesHundredsoflocallossesofspecieshavebeendrivenbyincreasesinsinceatleast1971(Figure3.4).Humaninﬂuenceisverylikelythemainthemagnitudeofheatextremes(highconﬁdence)andmassmortalitydriveroftheglobalretreatofglacierssincethe1990sandthedecreaseeventsonlandandintheocean(veryhighconﬁdence).ImpactsoninArcticseaiceareabetween1979–1988and2010–2019.HumansomeecosystemsareapproachingirreversibilitysuchastheimpactsinﬂuencehasalsoverylikelycontributedtodecreasedNorthernHemisphereofhydrologicalchangesresultingfromtheretreatofglaciers,orthespringsnowcoverandsurfacemeltingoftheGreenlandicesheet.Itischangesinsomemountain(mediumconﬁdence)andArcticecosystemsvirtuallycertainthathuman-causedCO2emissionsarethemaindriverdrivenbypermafrostthaw(highconﬁdence).Impactsinecosystemsofcurrentglobalacidiﬁcationofthesurfaceopenocean.{WGISPMA.1,fromslow-onsetprocessessuchasoceanacidiﬁcation,sealevelriseWGISPMA.1.3,WGISPMA.1.5,WGISPMA.1.6,WG1SPMA1.7,orregionaldecreasesinprecipitationhavealsobeenattributedtoWGISPMA.2,WG1.SPMA.4.2;SROCCSPM.A.1,SROCCSPMA.2}human-causedclimatechange(highconﬁdence).Climatechangehascontributedtodesertiﬁcationandexacerbatedlanddegradation,Human-causedclimatechangeisalreadyaffectingmanyweatherandparticularlyinlowlyingcoastalareas,riverdeltas,drylandsandinclimateextremesineveryregionacrosstheglobe.Evidenceofobservedpermafrostareas(highconﬁdence).Nearly50%ofcoastalwetlandschangesinextremessuchasheatwaves,heavyprecipitation,droughts,havebeenlostoverthelast100years,asaresultofthecombinedandtropicalcyclones,and,inparticular,theirattributiontohumaneffectsoflocalisedhumanpressures,sealevelrise,warminginﬂuence,hasstrengthenedsinceAR5(Figure2.3).Itisvirtuallycertainandextremeclimateevents(highconfidence).{WGIISPMB.1.1,thathotextremes(includingheatwaves)havebecomemorefrequentandWGIISPMB.1.2,WGIIFigureSPM.2.A,WGIITS.B.1;SRCCLSPMA.1.5,moreintenseacrossmostlandregionssincethe1950s(Figure2.3),whilecoldSRCCLSPMA.2,SRCCLSPMA.2.6,SRCCLFigureSPM.1;SROCCSPMA.6.1,extremes(includingcoldwaves)havebecomelessfrequentandlesssevere,SROCCSPM,A.6.4,SROCCSPMA.7}withhighconﬁdencethathuman-causedclimatechangeisthemaindriverofthesechanges.Marineheatwaveshaveapproximatelydoubled74‘Maindriver’meansresponsibleformorethan50%ofthechange.{WGISPMfootnote12}75SeeAnnexI:Glossary.46CurrentStatusandTrendsTable2.1:Assessmentofobservedchangesinlarge-scaleindicatorsofmeanclimateacrossclimatesystemcomponents,andtheirattributiontohumaninﬂuence.Thecolourcodingindicatestheassessedconﬁdencein/likelihood76oftheobservedchangeandthehumancontributionasadriverormaindriver(speciﬁedinthatcase)whereavailable(seecolourkey).Otherwise,explanatorytextisprovided.{WGITableTS.1}ChangeinindicatorObservedchangeHumancontributionassessmentassessmentAtmosphereWarmingofglobalmeansurfaceairtemperaturesince1850-1900likelyrangeofhumancontributionandwatercycle([0.8-1.3°C])encompassestheverylikelyrangeofobservedwarming([0.9-1.2°C])Warmingofthetropospheresince1979MaindriverCoolingofthelowerstratospheresincethemid-20thcenturyMaindriver1979-mid-1990sLarge-scaleprecipitationanduppertropospherehumiditychangessince1979SouthernHemisphereMaindriverOceanExpansionofthezonalmeanHadleyCirculationsincethe1980sOceanheatcontentincreasesincethe1970sSalinitychangessincethemid-20thcenturyCryosphereGlobalmeansealevelrisesince1970MaindriverArcticseaicelosssince1979MaindriverReductioninNorthernHemispherespringtimesnowcoversince1950Limitedevidence&mediumagreementMaindriverGreenlandicesheetmasslosssince1990sMaindriverMaindriverAntarcticicesheetmasslosssince1990sMaindriverCarboncycleRetreatofglaciersSection2LandclimateIncreasedamplitudeoftheseasonalcycleofSynthesisatmosphericCO2sincetheearly1960sAcidiﬁcationoftheglobalsurfaceoceanMeansurfaceairtemperatureoverland(about40%largerthanglobalmeanwarming)WarmingoftheglobalclimatesystemsincepreindustrialtimesKeymediumlikely/highverylikelyextremelyvirtuallyfactconﬁdenceconﬁdencelikelycertain76Basedonscientiﬁcunderstanding,keyﬁndingscanbeformulatedasstatementsoffactorassociatedwithanassessedlevelofconﬁdenceindicatedusingtheIPCCcalibratedlanguage.47Section2Climatechangehasimpactedhumanandnaturalsystemsacrosstheworldwiththosewhohavegenerallyleastcontributedtoclimatechangebeingmostvulnerablea)Synthesisofassessmentofobservedchangeinhotextremes,heavyprecipitationanddrought,andconﬁdenceinhumancontributiontotheobservedchangesintheworld’sregionsHotextremesincludingheatwavesDimensionofRisk:HazardNorthKeyAmericaNWNNENGICEuropeNEURARTypeofobservedchangesincethe1950sWNACNAENAWCEEEUWSBESBRFEAsiaIncreaseDecreaseNCAMEDWCAECATIBEASLimiteddataand/orliteratureSCACARLowagreementinthetypeofchangeCentralSmallSAHARPSASSEAAmericaIslandsNWSNSAWAFCAFNEAFNAUPACCAUEAUSmallSAMNESWSAFSEAFMDGIslandsConﬁdenceinhumancontributionAfricaESAFSAUtotheobservedchangeSouthSWSSESAustralasiaNZAmericaSSAHighMediumLowduetolimitedagreementLowduetolimitedevidenceHeavyprecipitationEuropeNEURAREachhexagoncorrespondsNorthtoaregionAmericaNWNNENGICWCEEEUWSBESBRFEAsiaNWNNorth-WesternWNACNAENANorthAmericaNCAMEDWCAECATIBEASIPCCAR6WGIreferenceregions:SCACARSectioSnec2tion1CentralSmallSAHARPSASSEANorthAmerica:NWN(North-WesternNorthAmericaIslandsAmerica,NEN(North-EasternNorthAmerica),WNA(WesternNorthAmerica),NWSNSAWAFCAFNEAFNAUPACCNA(CentralNorthAmerica),ENA(EasternCAUEAUSmallNorthAmerica),CentralAmerica:NCASAMNESWSAFSEAFMDGIslands(NorthernCentralAmerica),SCA(SouthernAfricaESAFSAUCentralAmerica),CAR(Caribbean),SouthSouthSWSSESAustralasiaNZAmerica:NWS(North-WesternSouthAmericaSSAAmerica),NSA(NorthernSouthAmerica),NES(North-EasternSouthAmerica),SAMAgriculturalandecologicaldrought(SouthAmericanMonsoon),SWS(South-WesternSouthAmerica),SESNorth(South-EasternSouthAmerica),SSAAmericaNWNNENGICEurope(SouthernSouthAmerica),Europe:GICNEURAR(Greenland/Iceland),NEU(NorthernEurope),WCE(WesternandCentralEurope),EEUWNACNAENAWCEEEUWSBESBRFEAsia(EasternEurope),MED(Mediterranean),Africa:MED(Mediterranean),SAH(Sahara),NCAMEDWCAECATIBEASWAF(WesternAfrica),CAF(CentralAfrica),SCACARNEAF(NorthEasternAfrica),SEAF(SouthCentralSmallSAHARPSASSEAEasternAfrica),WSAF(WestSouthernAmericaIslandsAfrica),ESAF(EastSouthernAfrica),MDG(Madagascar),Asia:RAR(RussianArctic),NWSNSAWAFCAFNEAFNAUPACWSB(WestSiberia),ESB(EastSiberia),RFECAUEAUSmall(RussianFarEast),WCA(WestCentralAsia),SAMNESWSAFSEAFMDGIslandsECA(EastCentralAsia),TIB(TibetanAfricaESAFSAUPlateau),EAS(EastAsia),ARP(ArabianSouthSWSSESAustralasiaNZPeninsula),SAS(SouthAsia),SEA(SouthEastAmericaSSAAsia),Australasia:NAU(NorthernAustralia),CAU(CentralAustralia),EAU(EasternAustralia),SAU(SouthernAustralia),NZ(NewZealand),SmallIslands:CAR(Caribbean),PAC(PaciﬁcSmallIslands)48CurrentStatusandTrendsb)Vulnerabilityofpopulation&percapitaemissionspercountryin2019DimensionVulnerabilityofRisk:high10090Relativeaveragenational80morevulnerableVulnerabilityassessedonnationaldata.vulnerabilitypercapitabyglobalcountriesgenerallyVulnerabilitydiffersbetweenandwithincountriesindicesINFORMandWRI(2019)haveloweremissionsandisexacerbatedbyinequityandmarginalisation.70percapita605040302010low01020304070800/2019emissionspercapitaof180nationsintonsofCO2c)ObservedimpactsandrelatedlossesGlobalanddamagesofclimatechangeAfricaAsiaAustralasiaCentral&SouthAmericaEuropeNorthAmericaSmallIslandsHUMANSYSTEMSWateravailabilityPhysicalwateravailabilityDimensionImpactSection2andfoodproductionAgriculture/cropproductionofRisk:KeyAnimalandlivestockhealthandproductivityIncreasedclimateimpactsFisheriesyieldsandaquacultureproductionHUMANSYSTEMSHealthandwellbeingInfectiousdiseasesAdverseimpactsAdverseandpositiveimpactsHeat,malnutritionandharmfromwildﬁreECOSYSTEMSCities,settlementsMentalhealthClimate-drivenchangesobserved,andinfrastructurenoassessmentofimpactdirectionChangesinDisplacementECOSYSTEMSecosystemstructureInlandﬂoodingandConﬁdenceinattributionassociateddamagestoclimatechangeFlood/storminduceddamagesincoastalareasHighorveryhighDamagestoinfrastructureMediumLowDamagestokeyeconomicsectorsEvidencelimited,insufﬁcientNotassessedTerrestrialFreshwaterSpeciesrangeshiftsOceanTerrestrialFreshwaterChangesinseasonalOceantiming(phenology)TerrestrialFreshwaterOcean49Section2Figure2.3:Bothvulnerabilitytocurrentclimateextremesandhistoricalcontributiontoclimatechangearehighlyheterogeneouswithmanyofthosewhohaveleastcontributedtoclimatechangetodatebeingmostvulnerabletoitsimpacts.Panel(a)TheIPCCAR6WGIinhabitedregionsaredisplayedashexagonswithidenticalsizeintheirapproximategeographicallocation(seelegendforregionalacronyms).Allassessmentsaremadeforeachregionasawholeandforthe1950stothepresent.Assessmentsmadeondifferenttimescalesormorelocalspatialscalesmightdifferfromwhatisshownintheﬁgure.Thecoloursineachpanelrepresentthefouroutcomesoftheassessmentonobservedchanges.Stripedhexagons(whiteandlight-grey)areusedwherethereislowagreementinthetypeofchangefortheregionasawhole,andgreyhexagonsareusedwhenthereislimiteddataand/orliteraturethatpreventsanassessmentoftheregionasawhole.Othercoloursindicateatleastmediumconﬁdenceintheobservedchange.Theconﬁdencelevelforthehumaninﬂuenceontheseobservedchangesisbasedonassessingtrenddetectionandattributionandeventattributionliterature,anditisindicatedbythenumberofdots:threedotsforhighconﬁdence,twodotsformediumconﬁdenceandonedotforlowconﬁdence(single,ﬁlleddot:limitedagreement;single,emptydot:limitedevidence).Forhotextremes,theevidenceismostlydrawnfromchangesinmetricsbasedondailymaximumtemperatures;regionalstudiesusingotherindices(heatwaveduration,frequencyandintensity)areusedinaddition.Forheavyprecipitation,theevidenceismostlydrawnfromchangesinindicesbasedonone-dayorﬁve-dayprecipitationamountsusingglobalandregionalstudies.Agriculturalandecologicaldroughtsareassessedbasedonobservedandsimulatedchangesintotalcolumnsoilmoisture,complementedbyevidenceonchangesinsurfacesoilmoisture,waterbalance(precipitationminusevapotranspiration)andindicesdrivenbyprecipitationandatmosphericevaporativedemand.Panel(b)showstheaveragelevelofvulnerabilityamongstacountry’spopulationagainst2019CO2-FFIemissionsper-capitapercountryforthe180countriesforwhichbothsetsofmetricsareavailable.Vulnerabilityinformationisbasedontwoglobalindicatorsystems,namelyINFORMandWorldRiskIndex.Countrieswitharelativelylowaveragevulnerabilityoftenhavegroupswithhighvulnerabilitywithintheirpopulationandviceversa.Theunderlyingdataincludes,forexample,informationonpoverty,inequality,healthcareinfrastructureorinsurancecoverage.Panel(c)Observedimpactsonecosystemsandhumansystemsattributedtoclimatechangeatglobalandregionalscales.Globalassessmentsfocusonlargestudies,multi-species,meta-analysesandlargereviews.Regionalassessmentsconsiderevidenceonimpactsacrossanentireregionanddonotfocusonanycountryinparticular.Forhumansystems,thedirectionofimpactsisassessedandbothadverseandpositiveimpactshavebeenobservede.g.,adverseimpactsinoneareaorfooditemmayoccurwithpositiveimpactsinanotherareaorfooditem(formoredetailsandmethodologyseeWGIISMTS.1).Physicalwateravailabilityincludesbalanceofwateravailablefromvarioussourcesincludinggroundwater,waterqualityanddemandforwater.Globalmentalhealthanddisplacementassessmentsreﬂectonlyassessedregions.Conﬁdencelevelsreﬂecttheassessmentofattributionoftheobservedimpacttoclimatechange.{WGIFigureSPM.3,TableTS.5,InteractiveAtlas;WGIIFigureSPM.2,WGIISMTS.1,WGII8.3.1,Figure8.5;;WGIII2.2.3}SectioSnec2tion1ClimatechangehasreducedfoodsecurityandaffectedwaterInurbansettings,climatechangehascausedadverseimpactsonsecurityduetowarming,changingprecipitationpatterns,humanhealth,livelihoodsandkeyinfrastructure(highconﬁdence).reductionandlossofcryosphericelements,andgreaterfrequencyHotextremesincludingheatwaveshaveintensiﬁedincities(highandintensityofclimaticextremes,therebyhinderingeffortstoconﬁdence),wheretheyhavealsoworsenedairpollutioneventsmeetSustainableDevelopmentGoals(highconﬁdence).Although(mediumconﬁdence)andlimitedfunctioningofkeyinfrastructureoverallagriculturalproductivityhasincreased,climatechangehasslowed(highconﬁdence).Urbaninfrastructure,includingtransportation,water,thisgrowthinagriculturalproductivityoverthepast50yearsgloballysanitationandenergysystemshavebeencompromisedbyextreme(mediumconﬁdence),withrelatednegativecropyieldimpactsmainlyandslow-onsetevents79,withresultingeconomiclosses,disruptionsofrecordedinmid-andlowlatituderegions,andsomepositiveimpactsservicesandimpactstowell-being(highconﬁdence).Observedimpactsinsomehighlatituderegions(highconﬁdence).Oceanwarminginareconcentratedamongsteconomicallyandsociallymarginalisedurbanthe20thcenturyandbeyondhascontributedtoanoveralldecreaseresidents,e.g.,thoselivingininformalsettlements(highconﬁdence).inmaximumcatchpotential(mediumconﬁdence),compoundingtheCitiesintensifyhuman-causedwarminglocally(veryhighconﬁdence),impactsfromoverﬁshingforsomeﬁshstocks(highconﬁdence).Oceanwhileurbanisationalsoincreasesmeanandheavyprecipitationoverand/orwarmingandoceanacidiﬁcationhaveadverselyaffectedfoodproductiondownwindofcities(mediumconﬁdence)andresultingrunoffintensityfromshellﬁshaquacultureandﬁsheriesinsomeoceanicregions(high(highconﬁdence).{WGISPMC.2.6;WGIISPMB.1.5,WGIIFigureTS.9,conﬁdence).CurrentlevelsofglobalwarmingareassociatedwithWGII6ES}moderaterisksfromincreaseddrylandwaterscarcity(highconﬁdence).Roughlyhalfoftheworld’spopulationcurrentlyexperiencesseverewaterClimatechangehasadverselyaffectedhumanphysicalhealthgloballyscarcityforatleastsomepartoftheyearduetoacombinationofclimaticandmentalhealthinassessedregions(veryhighconﬁdence),andisandnon-climaticdrivers(mediumconﬁdence)(Figure2.3).Unsustainablecontributingtohumanitariancriseswhereclimatehazardsinteractagriculturalexpansion,driveninpartbyunbalanceddiets77,increaseswithhighvulnerability(highconﬁdence).Inallregionsincreasesinecosystemandhumanvulnerabilityandleadstocompetitionforlandextremeheateventshaveresultedinhumanmortalityandmorbidityand/orwaterresources(highconﬁdence).Increasingweatherandclimate(veryhighconﬁdence).Theoccurrenceofclimate-relatedfood-borneandextremeeventshaveexposedmillionsofpeopletoacutefoodinsecurity78water-bornediseaseshasincreased(veryhighconﬁdence).Theincidenceandreducedwatersecurity,withthelargestimpactsobservedinmanyofvector-bornediseaseshasincreasedfromrangeexpansionand/orlocationsand/orcommunitiesinAfrica,Asia,CentralandSouthAmerica,increasedreproductionofdiseasevectors(highconﬁdence).AnimalandLDCs,SmallIslandsandtheArctic,andforsmall-scalefoodproducers,humandiseases,includingzoonoses,areemerginginnewareas(highlow-incomehouseholdsandIndigenousPeoplesglobally(highconﬁdence).conﬁdence).Inassessedregions,somementalhealthchallengesare{WGIISPMB.1.3,WGIISPM.B.2.3,WGIIFigureSPM.2,WGIITSB.2.3,associatedwithincreasingtemperatures(highconﬁdence),traumafromWGIITSFigureTS.6;SRCCLSPMA.2.8,SRCCLSPMA.5.3;SROCCSPMA.5.4.,extremeevents(veryhighconﬁdence),andlossoflivelihoodsandcultureSROCCSPMA.7.1,SROCCSPMA.8.1,SROCCFigureSPM.2}77Balanceddietsfeatureplant-basedfoods,suchasthosebasedoncoarsegrains,legumesfruitsandvegetables,nutsandseeds,andanimal-sourcefoodsproducedinresilient,sustainableandlow-GHGemissionssystems,asdescribedinSRCCL.{WGIISPMFootnote32}78Acutefoodinsecuritycanoccuratanytimewithaseveritythatthreatenslives,livelihoodsorboth,regardlessofthecauses,contextorduration,asaresultofshocksriskingdeterminantsoffoodsecurityandnutrition,andisusedtoassesstheneedforhumanitarianaction.{WGIISPM,footnote30}79Slow-onseteventsaredescribedamongtheclimatic-impactdriversoftheAR6WGIandrefertotherisksandimpactsassociatedwithe.g.,increasingtemperaturemeans,desertiﬁcation,decreasingprecipitation,lossofbiodiversity,landandforestdegradation,glacialretreatandrelatedimpacts,oceanacidiﬁcation,sealevelriseandsalinization.{WGIISPMfootnote29}50CurrentStatusandTrends(highconﬁdence)(Figure2.3).Climatechangeimpactsonhealtharetotangibleandintangibleheritage,threatenadaptivecapacityandmaySection2mediatedthroughnaturalandhumansystems,includingeconomicresultinirrevocablelossesofsenseofbelonging,valuedculturalpractices,andsocialconditionsanddisruptions(highconﬁdence).Climateandidentityandhome,particularlyforIndigenousPeoplesandthosemoreweatherextremesareincreasinglydrivingdisplacementinAfrica,directlyreliantontheenvironmentforsubsistence(mediumconﬁdence).Asia,NorthAmerica(highconﬁdence),andCentralandSouthAmericaForexample,changesinsnowcover,lakeandriverice,andpermafrost(mediumconﬁdence)(Figure2.3),withsmallislandstatesintheinmanyArcticregions,areharmingthelivelihoodsandculturalidentityCaribbeanandSouthPaciﬁcbeingdisproportionatelyaffectedrelativeofArcticresidentsincludingIndigenouspopulations(highconﬁdence).totheirsmallpopulationsize(highconﬁdence).ThroughdisplacementInfrastructure,includingtransportation,water,sanitationandenergyandinvoluntarymigrationfromextremeweatherandclimatesystemshavebeencompromisedbyextremeandslow-onsetevents,events,climatechangehasgeneratedandperpetuatedvulnerabilitywithresultingeconomiclosses,disruptionsofservicesandimpacts(mediumconﬁdence).{WGIISPMB.1.4,WGIISPMB.1.7}towell-being(highconﬁdence).{WGIISPMB.1,WGIISPMB.1.2,WGIISPM.B.1.5,WGIISPMC.3.5,WGIITS.B.1.6;SROCCSPMA.7.1}Humaninﬂuencehaslikelyincreasedthechanceofcompoundextremeevents80sincethe1950s.ConcurrentandrepeatedclimateAcrosssectorsandregions,themostvulnerablepeopleandhazardshaveoccurredinallregions,increasingimpactsandsystemshavebeendisproportionatelyaffectedbytheimpactsriskstohealth,ecosystems,infrastructure,livelihoodsandfoodofclimatechange(highconﬁdence).LDCsandSIDSwhohavemuch(highconﬁdence).Compoundextremeeventsincludeincreasesinthelowerpercapitaemissions(1.7tCO2-eq,4.6tCO2-eq,respectively)thanfrequencyofconcurrentheatwavesanddroughts(highconﬁdence);ﬁretheglobalaverage(6.9tCO2-eq)excludingCO2-LULUCF,alsohavehighweatherinsomeregions(mediumconﬁdence);andcompoundﬂoodinginvulnerabilitytoclimatichazards,withglobalhotspotsofhighhumansomelocations(mediumconﬁdence).Multiplerisksinteract,generatingvulnerabilityobservedinWest-,Central-andEastAfrica,SouthAsia,newsourcesofvulnerabilitytoclimatehazards,andcompoundingCentralandSouthAmerica,SIDSandtheArctic(highconﬁdence).overallrisk(highconﬁdence).CompoundclimatehazardscanoverwhelmRegionsandpeoplewithconsiderabledevelopmentconstraintshaveadaptivecapacityandsubstantiallyincreasedamage(highconﬁdence)).highvulnerabilitytoclimatichazards(highconﬁdence).Vulnerabilityis{WGISPMA.3.5;WGIISPM.B.5.1,WGIITS.C.11.3}higherinlocationswithpoverty,governancechallengesandlimitedaccesstobasicservicesandresources,violentconﬂictandhighlevelsEconomicimpactsattributabletoclimatechangeareincreasinglyofclimate-sensitivelivelihoods(e.g.,smallholderfarmers,pastoralists,affectingpeoples’livelihoodsandarecausingeconomicandﬁshingcommunities)(highconﬁdence).Vulnerabilityatdifferentspatialsocietalimpactsacrossnationalboundaries(highconﬁdence).levelsisexacerbatedbyinequityandmarginalisationlinkedtogender,Economicdamagesfromclimatechangehavebeendetectedinethnicity,lowincomeorcombinationsthereof(highconﬁdence),especiallyclimate-exposedsectors,withregionaleffectstoagriculture,forestry,formanyIndigenousPeoplesandlocalcommunities(highconﬁdence).ﬁshery,energy,andtourism,andthroughoutdoorlabourproductivityApproximately3.3to3.6billionpeopleliveincontextsthatarehighly(highconﬁdence)withsomeexceptionsofpositiveimpactsinregionsvulnerabletoclimatechange(highconﬁdence).Between2010andwithlowenergydemandandcomparativeadvantagesinagricultural2020,humanmortalityfromﬂoods,droughtsandstormswas15timesmarketsandtourism(highconﬁdence).Individuallivelihoodshavebeenhigherinhighlyvulnerableregions,comparedtoregionswithverylowaffectedthroughchangesinagriculturalproductivity,impactsonhumanvulnerability(highconﬁdence).IntheArcticandinsomehighmountainhealthandfoodsecurity,destructionofhomesandinfrastructure,andlossregions,negativeimpactsofcryospherechangehavebeenespeciallyfeltofpropertyandincome,withadverseeffectsongenderandsocialequityamongIndigenousPeoples(highconﬁdence).Humanandecosystem(highconﬁdence).Tropicalcycloneshavereducedeconomicgrowthinvulnerabilityareinterdependent(highconﬁdence).Vulnerabilityoftheshort-term(highconﬁdence).Eventattributionstudiesandphysicalecosystemsandpeopletoclimatechangedifferssubstantiallyamongandunderstandingindicatethathuman-causedclimatechangeincreaseswithinregions(veryhighconﬁdence),drivenbypatternsofintersectingheavyprecipitationassociatedwithtropicalcyclones(highconﬁdence).socio-economicdevelopment,unsustainableoceanandlanduse,Wildﬁresinmanyregionshaveaffectedbuiltassets,economicactivity,inequity,marginalisation,historicalandongoingpatternsofinequityandhealth(mediumtohighconﬁdence).Incitiesandsettlements,climatesuchascolonialism,andgovernance81(highconﬁdence).{WGIISPMB.1,impactstokeyinfrastructureareleadingtolossesanddamagesacrosswaterWGIISPMB.2,WGIISPMB.2.4;WGIIISPMB.3.1;SROCCSPMA.7.1,andfoodsystems,andaffecteconomicactivity,withimpactsextendingSROCCSPMA.7.2}beyondtheareadirectlyimpactedbytheclimatehazard(highconﬁdence).{WGISPMA.3.4;WGIISPMB.1.6,WGIISPMB.5.2,WGIISPMB.5.3}Climatechangehascausedwidespreadadverseimpactsandrelatedlossesanddamagestonatureandpeople(highconﬁdence).Lossesanddamagesareunequallydistributedacrosssystems,regionsandsectors(highconﬁdence).Culturallosses,related80SeeAnnex1:Glossary.81Governance:Thestructures,processesandactionsthroughwhichprivateandpublicactorsinteracttoaddresssocietalgoals.Thisincludesformalandinformalinstitutionsandtheassociatednorms,rules,lawsandproceduresfordeciding,managing,implementingandmonitoringpoliciesandmeasuresatanygeographicorpoliticalscale,fromglobaltolocal.{WGIISPMFootnote31}51Section22.2ResponsesUndertakentoDateInternationalclimateagreements,risingnationalambitionsforclimateaction,alongwithrisingpublicawarenessareacceleratingeffortstoaddressclimatechangeatmultiplelevelsofgovernance.Mitigationpolicieshavecontributedtoadecreaseinglobalenergyandcarbonintensity,withseveralcountriesachievingGHGemissionreductionsforoveradecade.Low-emissiontechnologiesarebecomingmoreaffordable,withmanyloworzeroemissionsoptionsnowavailableforenergy,buildings,transport,andindustry.Adaptationplanningandimplementationprogresshasgeneratedmultiplebeneﬁts,witheffectiveadaptationoptionshavingthepotentialtoreduceclimaterisksandcontributetosustainabledevelopment.GlobaltrackedﬁnanceformitigationandadaptationhasseenanupwardtrendsinceAR5,butfallsshortofneeds.(highconﬁdence)SectioSnec2tion12.2.1.GlobalPolicySettingconﬁdence).Masssocialmovementshaveemergedascatalysingagentsinsomeregions,oftenbuildingonpriormovementsincludingTheUnitedNationsFrameworkConventiononClimateChange(UNFCCC),IndigenousPeoples-ledmovements,youthmovements,humanKyotoProtocol,andParisAgreementaresupportingrisinglevelsofrightsmovements,genderactivism,andclimatelitigation,whichisnationalambitionandencouragingthedevelopmentandimplementationraisingawarenessand,insomecases,hasinﬂuencedtheoutcomeofclimatepoliciesatmultiplelevelsofgovernance(highconﬁdence).andambitionofclimategovernance(mediumconﬁdence).EngagingTheKyotoProtocolledtoreducedemissionsinsomecountriesandIndigenousPeoplesandlocalcommunitiesusingjust-transitionandwasinstrumentalinbuildingnationalandinternationalcapacityrights-baseddecision-makingapproaches,implementedthroughforGHGreporting,accountingandemissionsmarkets(highcollectiveandparticipatorydecision-makingprocesseshasenabledconfidence).TheParisAgreement,adoptedundertheUNFCCC,withdeeperambitionandacceleratedactionindifferentways,andatallnearuniversalparticipation,hasledtopolicydevelopmentandscales,dependingonnationalcircumstances(mediumconﬁdence).target-settingatnationalandsub-nationallevels,particularlyinThemediahelpsshapethepublicdiscourseaboutclimatechange.Thisrelationtomitigationbutalsoforadaptation,aswellasenhancedcanusefullybuildpublicsupporttoaccelerateclimateaction(mediumtransparencyofclimateactionandsupport(mediumconfidence).evidence,highagreement).Insomeinstances,publicdiscoursesofNationallyDeterminedContributions(NDCs),requiredundermediaandorganisedcountermovementshaveimpededclimatetheParisAgreement,haverequiredcountriestoarticulatetheiraction,exacerbatinghelplessnessanddisinformationandfuellingprioritiesandambitionwithrespecttoclimateaction.{WGII17.4,polarisation,withnegativeimplicationsforclimateaction(mediumWGIITSD.1.1;WGIIISPMB.5.1,WGIIISPME.6}conﬁdence).{WGIISPMC.5.1,WGIISPMD.2,WGIITS.D.9,WGIITS.D.9.7,WGIITS.E.2.1,WGII18.4;WGIIISPMD.3.3,WGIIISPME.3.3,WGIIITS.6.1,Loss&Damage82wasformallyrecognizedin2013throughestablishmentWGIII6.7,WGIII13ES,WGIIIBox.13.7}oftheWarsawInternationalMechanismonLossandDamage(WIM),andin2015,Article8oftheParisAgreementprovidedalegalbasis2.2.2.MitigationActionstoDatefortheWIM.Thereisimprovedunderstandingofbotheconomicandnon-economiclossesanddamages,whichisinforminginternationalTherehasbeenaconsistentexpansionofpoliciesandlawsclimatepolicyandwhichhashighlightedthatlossesanddamagesareaddressingmitigationsinceAR5(highconﬁdence).Climatenotcomprehensivelyaddressedbycurrentﬁnancial,governanceandgovernancesupportsmitigationbyprovidingframeworksthroughinstitutionalarrangements,particularlyinvulnerabledevelopingcountrieswhichdiverseactorsinteract,andabasisforpolicydevelopmentand(highconﬁdence).{WGIISPMC.3.5,WGIICross-ChapterBoxLOSS}implementation(mediumconﬁdence).Manyregulatoryandeconomicinstrumentshavealreadybeendeployedsuccessfully(highconﬁdence).OtherrecentglobalagreementsthatinﬂuenceresponsestoclimateBy2020,lawsprimarilyfocussedonreducingGHGemissionsexistedinchangeincludetheSendaiFrameworkforDisasterRiskReduction56countriescovering53%ofglobalemissions(mediumconﬁdence).(2015-2030),theﬁnance-orientedAddisAbabaActionAgenda(2015)TheapplicationofdiversepolicyinstrumentsformitigationattheandtheNewUrbanAgenda(2016),andtheKigaliAmendmenttonationalandsub-nationallevelshasgrownconsistentlyacrossatheMontrealProtocolonSubstancesthatDepletetheOzoneLayerrangeofsectors(highconﬁdence).Policycoverageisunevenacross(2016),amongothers.Inaddition,the2030AgendaforSustainablesectorsandremainslimitedforemissionsfromagriculture,andfromDevelopment,adoptedin2015byUNmemberstates,setsout17industrialmaterialsandfeedstocks(highconﬁdence).{WGIIISPMB.5,SustainableDevelopmentGoals(SDGs)andseekstoaligneffortsWGIIISPMB.5.2,WGIIISPME.3,WGIIISPME.4}globallytoprioritiseendingextremepoverty,protecttheplanetandpromotemorepeaceful,prosperousandinclusivesocieties.Ifachieved,Practicalexperiencehasinformedeconomicinstrumentdesigntheseagreementswouldreduceclimatechange,andtheimpactsonandhelpedtoimprovepredictability,environmentaleffectiveness,health,well-being,migration,andconﬂict,amongothers(veryhigheconomicefﬁciency,alignmentwithdistributionalgoals,andsocialconﬁdence).{WGIITS.A.1,WGII7ES}acceptance(highconﬁdence).Low-emissiontechnologicalinnovationisstrengthenedthroughthecombinationoftechnology-pushpolicies,SinceAR5,risingpublicawarenessandanincreasingdiversitytogetherwithpoliciesthatcreateincentivesforbehaviourchangeandofactors,haveoverallhelpedacceleratepoliticalcommitmentmarketopportunities(highconﬁdence)(Section4.8.3).Comprehensiveandglobaleffortstoaddressclimatechange(mediumandconsistentpolicypackageshavebeenfoundtobemoreeffective82SeeAnnexI:Glossary.52CurrentStatusandTrendsthansinglepolicies(highconﬁdence).Combiningmitigationwithincreasinglycosteffectiveandaregenerallysupportedbythepublic,andSection2policiestoshiftdevelopmentpathways,policiesthatinducelifestyleorthisenablesexpandeddeploymentinmanyregions.(highconﬁdence)behaviourchanges,forexample,measurespromotingwalkableurban{WGIIISPMB.4.3,WGIIISPMC.5.2,WGIIISPMC.7.2,WGIIISPME.1.1,areascombinedwithelectriﬁcationandrenewableenergycancreateWGIIITS.6.5}healthco-beneﬁtsfromcleanerairandenhancedactivemobility(highconﬁdence).ClimategovernanceenablesmitigationbyprovidinganThemagnitudeofglobalclimateﬁnanceﬂowshasincreasedoveralldirection,settingtargets,mainstreamingclimateactionacrossandﬁnancingchannelshavebroadened(highconﬁdence).policydomainsandlevels,basedonnationalcircumstancesandintheAnnualtrackedtotalﬁnancialﬂowsforclimatemitigationandcontextofinternationalcooperation.Effectivegovernanceenhancesadaptationincreasedbyupto60%between2013/14and2019/20,regulatorycertainty,creatingspecialisedorganisationsandcreatingthebutaveragegrowthhasslowedsince2018(mediumconﬁdence)andcontexttomobiliseﬁnance(mediumconﬁdence).Thesefunctionscanmostclimateﬁnancestayswithinnationalborders(highconﬁdence).bepromotedbyclimate-relevantlaws,whicharegrowinginnumber,orMarketsforgreenbonds,environmental,socialandgovernanceandclimatestrategies,amongothers,basedonnationalandsub-nationalsustainableﬁnanceproductshaveexpandedsigniﬁcantlysinceAR5context(mediumconﬁdence).Effectiveandequitableclimate(highconﬁdence).Investors,centralbanks,andﬁnancialregulatorsaregovernancebuildsonengagementwithcivilsocietyactors,politicaldrivingincreasedawarenessofclimaterisktosupportclimatepolicyactors,businesses,youth,labour,media,IndigenousPeoplesandlocaldevelopmentandimplementation(highconﬁdence).Acceleratedcommunities(mediumconﬁdence).{WGIIISPME.2.2,WGIIISPME.3,internationalﬁnancialcooperationisacriticalenableroflow-GHGandWGIIISPME.3.1,WGIIISPME.4.2,WGIIISPME.4.3,WGIIISPME.4.4}justtransitions(highconﬁdence).{WGIIISPMB.5.4,WGIIISPME.5,WGIIITS.6.3,WGIIITS.6.4}Theunitcostsofseverallow-emissiontechnologies,includingsolar,windandlithium-ionbatteries,havefallenconsistentlyEconomicinstrumentshavebeeneffectiveinreducingemissions,since2010(Figure2.4).Designandprocessinnovationsincomplementedbyregulatoryinstrumentsmainlyatthenationalcombinationwiththeuseofdigitaltechnologieshaveledtoandalsosub-nationalandregionallevel(highconﬁdence).By2020,near-commercialavailabilityofmanyloworzeroemissionsover20%ofglobalGHGemissionswerecoveredbycarbontaxesoroptionsinbuildings,transportandindustry.From2010-2019,emissionstradingsystems,althoughcoverageandpriceshavebeentherehavebeensustaineddecreasesintheunitcostsofsolarenergyinsufﬁcienttoachievedeepreductions(mediumconﬁdence).Equityand(by85%),windenergy(by55%),andlithium-ionbatteries(by85%),distributionalimpactsofcarbonpricinginstrumentscanbeaddressedandlargeincreasesintheirdeployment,e.g.,>10×forsolarand>100×forbyusingrevenuefromcarbontaxesoremissionstradingtosupportelectricvehicles(EVs),albeitvaryingwidelyacrossregions(Figure2.4).low-incomehouseholds,amongotherapproaches(highconﬁdence).ElectricityfromPVandwindisnowcheaperthanelectricityfromThemixofpolicyinstrumentswhichreducedcostsandstimulatedfossilsourcesinmanyregions,electricvehiclesareincreasinglyadoptionofsolarenergy,windenergyandlithium-ionbatteriescompetitivewithinternalcombustionengines,andlarge-scaleincludespublicR&D,fundingfordemonstrationandpilotprojects,andbatterystorageonelectricitygridsisincreasinglyviable.Indemand-pullinstrumentssuchasdeploymentsubsidiestoattainscalecomparisontomodularsmall-unitsizetechnologies,theempirical(highconﬁdence)(Figure2.4).{WGIIISPMB.4.1,WGIIISPMB.5.2,recordshowsthatmultiplelarge-scalemitigationtechnologies,withWGIIISPME.4.2,WGIIITS.3}feweropportunitiesforlearning,haveseenminimalcostreductionsandtheiradoptionhasgrownslowly.Maintainingemission-intensiveMitigationactions,supportedbypolicies,havecontributedsystemsmay,insomeregionsandsectors,bemoreexpensivethantoadecreaseinglobalenergyandcarbonintensitybetweentransitioningtolowemissionsystems.(highconﬁdence){WGIIISPMB.4,2010and2019,withagrowingnumberofcountriesachievingWGIIISPMB.4.1,WGIIISPMC.4.2,WGIIISPMC.5.2,WGIIISPMC.7.2,absoluteGHGemissionreductionsformorethanadecade(highWGIIISPMC.8,WGIIIFigureSPM.3,WGIIIFigureSPM.3}conﬁdence).WhileglobalnetGHGemissionshaveincreasedsince2010,globalenergyintensity(totalprimaryenergyperunitGDP)Foralmostallbasicmaterials–primarymetals,buildingmaterialsanddecreasedby2%yr–1between2010and2019.Globalcarbonchemicals–manylow-tozero-GHGintensityproductionprocessesareintensity(CO2-FFIperunitprimaryenergy)alsodecreasedby0.3%atthepilottonear-commercialandinsomecasescommercialstageyr–1,mainlyduetofuelswitchingfromcoaltogas,reducedexpansionbuttheyarenotyetestablishedindustrialpractice.Integrateddesignofcoalcapacity,andincreaseduseofrenewables,andwithlargeinconstructionandretroﬁtofbuildingshasledtoincreasingexamplesregionalvariationsoverthesameperiod.Inmanycountries,policiesofzeroenergyorzerocarbonbuildings.Technologicalinnovationhaveenhancedenergyefﬁciency,reducedratesofdeforestationandmadepossiblethewidespreadadoptionofLEDlighting.Digitalacceleratedtechnologydeployment,leadingtoavoidedandinsometechnologiesincludingsensors,theinternetofthings,robotics,andcasesreducedorremovedemissions(highconﬁdence).Atleastartiﬁcialintelligencecanimproveenergymanagementinallsectors;18countrieshavesustainedproduction-basedCO2andGHGandtheycanincreaseenergyefﬁciency,andpromotetheadoptionofmanyconsumption-basedCO2absoluteemissionreductionsforlongerthanlow-emissiontechnologies,includingdecentralisedrenewableenergy,10yearssince2005throughenergysupplydecarbonization,energywhilecreatingeconomicopportunities.However,someoftheseclimateefﬁciencygains,andenergydemandreduction,whichresultedfromchangemitigationgainscanbereducedorcounterbalancedbygrowthinbothpoliciesandchangesineconomicstructure(highconﬁdence).demandforgoodsandservicesduetotheuseofdigitaldevices.SeveralSomecountrieshavereducedproduction-basedGHGemissionsbyamitigationoptions,notablysolarenergy,windenergy,electriﬁcationofthirdormoresincepeaking,andsomehaveachievedreductionratesurbansystems,urbangreeninfrastructure,energyefﬁciency,demandofaround4%yr–1forseveralyearsconsecutively(highconﬁdence).sidemanagement,improvedforest-andcrop/grasslandmanagement,Multiplelinesofevidencesuggestthatmitigationpolicieshaveledtoandreducedfoodwasteandloss,aretechnicallyviable,arebecomingavoidedglobalemissionsofseveralGtCO2-eqyr–1(mediumconﬁdence).53Section2Renewableelectricitygenerationisincreasinglyprice-competitiveandsomesectorsareelectrifyinga)MarketCostCost($2020/MWh)PhotovoltaicsOnshoreOffshoreCost($2020/kWh)Passenger(PV)windwindelectricvehicleSinceAR5,theunitcostsofsome6001600Li-ionbatterypacksformsofrenewableenergyand45020102010ofbatteriesforpassengerEVs300401200havefallen.Adoption(GW)-notedifferntscales30Adoption(millionsofEVs)15020800belowthispoint,costscan0belessthanfossilfuels2010400Fossilfuelcost(2020)80006002010b)MarketAdoption4008SinceAR5,theinstalledcapacity6ofrenewableenergieshasincreasedmultipletimes.4200102SectioSnec2tion10002010201020102010Key200020102020Marketcost,withrangeFossilfuelcost(2020)Adoption(notedifferentscales)Figure2.4:Unitcostreductionsanduseinsomerapidlychangingmitigationtechnologies.Thetoppanel(a)showsglobalcostsperunitofenergy(USDperMWh)forsomerapidlychangingmitigationtechnologies.Solidbluelinesindicateaverageunitcostineachyear.Lightblueshadedareasshowtherangebetweenthe5thand95thpercentilesineachyear.Yellowshadingindicatestherangeofunitcostsfornewfossilfuel(coalandgas)powerin2020(correspondingtoUSD55to148perMWh).In2020,thelevelisedcostsofenergy(LCOE)ofthethreerenewableenergytechnologiescouldcompetewithfossilfuelsinmanyplaces.Forbatteries,costsshownarefor1kWhofbatterystoragecapacity;fortheothers,costsareLCOE,whichincludesinstallation,capital,operations,andmaintenancecostsperMWhofelectricityproduced.TheliteratureusesLCOEbecauseitallowsconsistentcomparisonsofcosttrendsacrossadiversesetofenergytechnologiestobemade.However,itdoesnotincludethecostsofgridintegrationorclimateimpacts.Further,LCOEdoesnottakeintoaccountotherenvironmentalandsocialexternalitiesthatmaymodifytheoverall(monetaryandnon-monetary)costsoftechnologiesandaltertheirdeployment.Thebottompanel(b)showscumulativeglobaladoptionforeachtechnology,inGWofinstalledcapacityforrenewableenergyandinmillionsofvehiclesforbattery-electricvehicles.Averticaldashedlineisplacedin2010toindicatethechangeoverthepastdecade.Theelectricityproductionsharereﬂectsdifferentcapacityfactors;forexample,forthesameamountofinstalledcapacity,windproducesabouttwiceasmuchelectricityassolarPV.Renewableenergyandbatterytechnologieswereselectedasillustrativeexamplesbecausetheyhaverecentlyshownrapidchangesincostsandadoption,andbecauseconsistentdataareavailable.OthermitigationoptionsassessedintheWGIIIreportarenotincludedastheydonotmeetthesecriteria.{WGIIIFigureSPM.3,WGIII2.5,6.4}54CurrentStatusandTrendsAtleast1.8GtCO2-eqyr–1ofavoidedemissionscanbeaccountedforindisasterriskmanagement,socialsafetynetsandgreen/blueSection2byaggregatingseparateestimatesfortheeffectsofeconomicandinfrastructure(mediumconﬁdence).Manyadaptationmeasuresthatregulatoryinstruments(mediumconﬁdence).Growingnumbersofbeneﬁthealthandwell-beingarefoundinothersectors(e.g.,food,lawsandexecutiveordershaveimpactedglobalemissionsandarelivelihoods,socialprotection,waterandsanitation,infrastructure)estimatedtohaveresultedin5.9GtCO2-eqyr–1ofavoidedemissions(highconﬁdence).{WGIISPMC.2.1,WGIISPMC.2.2,WGIITS.D.1.2,in2016(mediumconﬁdence).ThesereductionshaveonlypartlyoffsetWGIITS.D.1.4,WGIITS.D.4.2,WGIITS.D.8.3,WGII4ES;SRCCLSPMB.1.1}globalemissionsgrowth(highconfidence).{WGIIISPMB.1,WGIIISPMB.2.4,WGIIISPMB.3.5,WGIIISPMB.5.1,WGIIISPMB.5.3,AdaptationcangeneratemultipleadditionalbeneﬁtssuchasimprovingWGIII1.3.2,WGIII2.2.3}agriculturalproductivity,innovation,healthandwell-being,foodsecurity,livelihood,andbiodiversityconservationaswellasreduction2.2.3.AdaptationActionstoDateofrisksanddamages(veryhighconﬁdence).{WGIISPMC1.1}ProgressinadaptationplanningandimplementationhasbeenGloballytrackedadaptationﬁnancehasshownanupwardtrendobservedacrossallsectorsandregions,generatingmultiplesinceAR5,butrepresentsonlyasmallportionoftotalclimatebeneﬁts(veryhighconﬁdence).Theambition,scopeandprogressﬁnance,isunevenandhasdevelopedheterogeneouslyacrossonadaptationhaverisenamonggovernmentsatthelocal,nationalandregionsandsectors(highconﬁdence).Adaptationﬁnancehascomeinternationallevels,alongwithbusinesses,communitiesandcivilsocietypredominantlyfrompublicsources,largelythroughgrants,concessional(highconﬁdence).Varioustools,measuresandprocessesareavailableandnon-concessionalinstruments(veryhighconﬁdence).Globally,thatcanenable,accelerateandsustainadaptationimplementationprivate-sectorﬁnancingofadaptationfromavarietyofsourcessuch(highconﬁdence).Growingpublicandpoliticalawarenessofclimateascommercialﬁnancialinstitutions,institutionalinvestors,otherimpactsandriskshasresultedinatleast170countriesandmanycitiesprivateequity,non-ﬁnancialcorporations,aswellascommunitiesincludingadaptationintheirclimatepoliciesandplanningprocessesandhouseholdshasbeenlimited,especiallyindevelopingcountries(highconﬁdence).Decisionsupporttoolsandclimateservicesare(highconﬁdence).Publicmechanismsandﬁnancecanleverageincreasinglybeingused(veryhighconﬁdence)andpilotprojectsandprivatesectorﬁnanceforadaptationbyaddressingrealandperceivedlocalexperimentsarebeingimplementedindifferentsectors(highregulatory,costandmarketbarriers,forexampleviapublic-privateconﬁdence).{WGIISPMC.1,WGIISPM.C.1.1,WGIITS.D.1.3,WGIITS.D.10}partnerships(highconﬁdence).Innovationsinadaptationandresilienceﬁnance,suchasforecast-based/anticipatoryﬁnancingAdaptationtowater-relatedrisksandimpactsmakeupthemajority(~60%)systemsandregionalriskinsurancepools,havebeenpilotedandareofalldocumented83adaptation(highconﬁdence).Alargenumberofgrowinginscale(highconﬁdence).{WGIISPMC.3.2,WGIISPMC.5.4;theseadaptationresponsesareintheagriculturesectorandtheseWGIITS.D.1.6,WGIICross-ChapterBoxFINANCE;WGIIISPME.5.4}includeon-farmwatermanagement,waterstorage,soilmoistureconservation,andirrigation.OtheradaptationsinagricultureincludeThereareadaptationoptionswhichareeffective84inreducingcultivarimprovements,agroforestry,community-basedadaptationandclimaterisks85forspeciﬁccontexts,sectorsandregionsandfarmandlandscapediversiﬁcationamongothers(highconﬁdence).contributepositivelytosustainabledevelopmentandotherForinlandﬂooding,combinationsofnon-structuralmeasureslikesocietalgoals.Intheagriculturesector,cultivarimprovements,earlywarningsystems,enhancingnaturalwaterretentionsuchasbyon-farmwatermanagementandstorage,soilmoistureconservation,restoringwetlandsandrivers,andlanduseplanningsuchasnobuildirrigation86,agroforestry,community-basedadaptation,andfarmandzonesorupstreamforestmanagement,canreduceﬂoodrisk(mediumlandscapeleveldiversiﬁcation,andsustainablelandmanagementconﬁdence).Someland-relatedadaptationactionssuchassustainableapproaches,providemultiplebeneﬁtsandreduceclimaterisks.foodproduction,improvedandsustainableforestmanagement,Reductionoffoodlossandwaste,andadaptationmeasuresinsupportsoilorganiccarbonmanagement,ecosystemconservationandlandofbalanceddietscontributetonutrition,health,andbiodiversitybeneﬁts.restoration,reduceddeforestationanddegradation,andreduced(highconﬁdence){WGIISPMC.2,WGIISPMC.2.1,WGIISPMC.2.2;foodlossandwastearebeingundertaken,andcanhavemitigationSRCCLB.2,SRCCLSPMC.2.1}co-beneﬁts(highconﬁdence).AdaptationactionsthatincreasetheresilienceofbiodiversityandecosystemservicestoclimatechangeEcosystem-basedAdaptation87approachessuchasurbangreening,includeresponseslikeminimisingadditionalstressesordisturbances,restorationofwetlandsandupstreamforestecosystemsreducereducingfragmentation,increasingnaturalhabitatextent,connectivityarangeofclimatechangerisks,includingﬂoodrisks,urbanheatandheterogeneity,andprotectingsmall-scalerefugiawhereandprovidemultipleco-beneﬁts.Someland-basedadaptationmicroclimateconditionscanallowspeciestopersist(highconﬁdence).optionsprovideimmediatebeneﬁts(e.g.,conservationofpeatlands,Mostinnovationsinurbanadaptationhaveoccurredthroughadvances83Documentedadaptationreferstopublishedliteratureonadaptationpolicies,measuresandactionsthathasbeenimplementedanddocumentedinpeerreviewedliterature,asopposedtoadaptationthatmayhavebeenplanned,butnotimplemented.84Effectivenessrefersheretotheextenttowhichanadaptationoptionisanticipatedorobservedtoreduceclimate-relatedrisk.85SeeAnnexI:Glossary.86Irrigationiseffectiveinreducingdroughtriskandclimateimpactsinmanyregionsandhasseverallivelihoodbeneﬁts,butneedsappropriatemanagementtoavoidpotentialadverseoutcomes,whichcanincludeaccelerateddepletionofgroundwaterandotherwatersourcesandincreasedsoilsalinization(mediumconﬁdence).87EbAisrecognisedinternationallyundertheConventiononBiologicalDiversity(CBD14/5).ArelatedconceptisNature-basedSolutions(NbS),seeAnnexI:Glossary.55SectioSnec2tion1Section2wetlands,rangelands,mangrovesandforests);whileafforestationandreforestation,restorationofhigh-carbonecosystems,agroforestry,andthereclamationofdegradedsoilstakemoretimetodelivermeasurableresults.Signiﬁcantsynergiesexistbetweenadaptationandmitigation,forexamplethroughsustainablelandmanagementapproaches.Agroecologicalprinciplesandpracticesandotherapproachesthatworkwithnaturalprocessessupportfoodsecurity,nutrition,healthandwell-being,livelihoodsandbiodiversity,sustainabilityandecosystemservices.(highconﬁdence){WGIISPMC.2.1,WGIISPMC.2.2,WGIISPMC.2.5,WGIITS.D.4.1;SRCCLSPMB.1.2,SRCCLSPM.B.6.1;SROCCSPMC.2}Combinationsofnon-structuralmeasureslikeearlywarningsystemsandstructuralmeasureslikeleveeshavereducedlossoflivesincaseofinlandﬂooding(mediumconﬁdence)andearlywarningsystemsalongwithﬂood-prooﬁngofbuildingshaveproventobecost-effectiveinthecontextofcoastalﬂoodingundercurrentsealevelrise(highconﬁdence).HeatHealthActionPlansthatincludeearlywarningandresponsesystemsareeffectiveadaptationoptionsforextremeheat(highconﬁdence).Effectiveadaptationoptionsforwater,foodandvector-bornediseasesincludeimprovingaccesstopotablewater,reducingexposureofwaterandsanitationsystemstoextremeweatherevents,andimprovedearlywarningsystems,surveillance,andvaccinedevelopment(veryhighconﬁdence).Adaptationoptionssuchasdisasterriskmanagement,earlywarningsystems,climateservicesandsocialsafetynetshavebroadapplicabilityacrossmultiplesectors(highconﬁdence).{WGIISPMC.2.1,WGIISPMC.2.5,WGIISPMC.2.9,WGIISPMC.2.11,WGIISPMC.2.13;SROCCSPMC.3.2}Integrated,multi-sectoralsolutionsthataddresssocialinequities,differentiateresponsesbasedonclimateriskandcutacrosssystems,increasethefeasibilityandeffectivenessofadaptationinmultiplesectors(highconﬁdence).{WGIISPMC.2}56CurrentStatusandTrends2.3CurrentMitigationandAdaptationActionsandPoliciesarenotSufﬁcientAtthetimeofthepresentassessment88therearegapsbetweenglobalambitionsandthesumofdeclarednationalambitions.Thesearefurthercompoundedbygapsbetweendeclarednationalambitionsandcurrentimplementationforallaspectsofclimateaction.Formitigation,globalGHGemissionsin2030impliedbyNDCsannouncedbyOctober2021wouldmakeitlikelythatwarmingwillexceed1.5°Cduringthe21stcenturyandwouldmakeithardertolimitwarmingbelow2°C.89Despiteprogress,adaptationgaps90persist,withmanyinitiativesprioritisingshort-termriskreduction,hinderingtransformationaladaptation.Hardandsoftlimitstoadaptationarebeingreachedinsomesectorsandregions,whilemaladaptationisalsoincreasinganddisproportionatelyaffectingvulnerablegroups.Systemicbarrierssuchasfunding,knowledge,andpracticegaps,includinglackofclimateliteracyanddatahindersadaptationprogress.Insufﬁcientﬁnancing,especiallyforadaptation,constraintsclimateactioninparticularindevelopingcountries.(highconﬁdence)88Thetimingofvariouscut-offsforassessmentdiffersbyWGreportandtheaspectassessed.Seefootnote1inSection1.829.3.S1e.eTChSBe.2GfoarapdBisceutsswioneoefnsceMnairtioisgaantdipoanthwPaoysl.icies,Pledgesandtoamedianglobalwarmingof2.8[2.1to3.4]°Cby2100(mediumSection2PathwaysthatLimitWarmingto1.5°CorBelow2°Cconﬁdence).Ifthe‘emissiongap’isnotreduced,globalGHGemissionsin2030consistentwithNDCsannouncedpriortoCOP26makeitlikely90SeeAnnexI:Glossary.thatwarmingwillexceed1.5°Cduringthe21stcentury,whilelimitingwarmingto2°C(>67%)wouldimplyanunprecedentedaccelerationofGlobalGHGemissionsin2030associatedwiththeimplementationmitigationeffortsduring2030–2050(mediumconﬁdence)(seeSection4.1,ofNDCsannouncedpriortoCOP2691wouldmakeitlikelythatCross-SectionBox.2).{WGIIISPMB.6,WGIIISPMB.6.1,WGIIISPMB.6.3,warmingwillexceed1.5°Cduringthe21stcenturyandwouldWGIIISPMB.6.4,WGIIISPMC.1.1}makeithardertolimitwarmingbelow2°C–ifnoadditionalcommitmentsaremadeoractionstaken(Figure2.5,Table2.2).Policiesimplementedbytheendof2020areprojectedtoresultinAsubstantial‘emissionsgap’existsasglobalGHGemissionsin2030higherglobalGHGemissionsin2030thanthoseimpliedbyNDCs,associatedwiththeimplementationofNDCsannouncedpriortoCOP26indicatingan‘implementationgap94’(highconﬁdence)(Table2.2,wouldbesimilartooronlyslightlybelow2019emissionlevelsandFigure2.5).Projectedglobalemissionsimpliedbypoliciesimplementedhigherthanthoseassociatedwithmodelledmitigationpathwaysthatbytheendof2020are57(52–60)GtCO2-eqin2030(Table2.2).Thislimitwarmingto1.5°C(>50%)withnoorlimitedovershootortopointstoanimplementationgapcomparedwiththeNDCsof4to2°C(>67%),assumingimmediateaction,whichimpliesdeep,rapid,7GtCO2-eqin2030(Table2.2);withoutastrengtheningofpolicies,andsustainedglobalGHGemissionreductionsthisdecade(highemissionsareprojectedtorise,leadingtoamedianglobalwarmingconﬁdence)(Table2.2,Table3.1,4.1).92Themagnitudeoftheemissionsof2.2°Cto3.5°C(verylikelyrange)by2100(mediumconfidence)gapdependsontheglobalwarminglevelconsideredandwhetheronly(seeSection3.1.1).{WGIIISPMB.6.1,WGIIISPMC.1}unconditionaloralsoconditionalelementsofNDCs93areconsidered(highconﬁdence)(Table2.2).ModelledpathwaysthatareconsistentwithNDCsannouncedpriortoCOP26until2030andassumenoincreaseinambitionthereafterhavehigheremissions,leading88Thetimingofvariouscut-offsforassessmentdiffersbyWGreportandtheaspectassessed.Seefootnote58inSection1.89SeeCSB.2foradiscussionofscenariosandpathways.90SeeAnnexI:Glossary.91NDCsannouncedpriortoCOP26refertothemostrecentNDCssubmittedtotheUNFCCCuptotheliteraturecut-offdateoftheWGIIIreport,11October2021,andrevisedNDCsannouncedbyChina,JapanandtheRepublicofKoreapriortoOctober2021butonlysubmittedthereafter.25NDCupdatesweresubmittedbetween12October2021andthestartofCOP26.{WGIIISPMfootnote24}92Immediateactioninmodelledglobalpathwaysreferstotheadoptionbetween2020andatlatestbefore2025ofclimatepoliciesintendedtolimitglobalwarmingtoagivenlevel.Modelledpathwaysthatlimitwarmingto2°C(>67%)basedonimmediateactionaresummarisedincategoryC3ainTable3.1.Allassessedmodelledglobalpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershootassumeimmediateactionasdeﬁnedhere(CategoryC1inTable3.1).{WGIIISPMfootnote26}93Inthisreport,‘unconditional’elementsofNDCsrefertomitigationeffortsputforwardwithoutanyconditions.‘Conditional’elementsrefertomitigationeffortsthatarecontingentoninternationalcooperation,forexamplebilateralandmultilateralagreements,ﬁnancingormonetaryand/ortechnologicaltransfers.ThisterminologyisusedintheliteratureandtheUNFCCC’sNDCSynthesisReports,notbytheParisAgreement.{WGIIISPMfootnote27}94Implementationgapsrefertohowfarcurrentlyenactedpoliciesandactionsfallshortofreachingthepledges.Thepolicycut-offdateinstudiesusedtoprojectGHGemissionsof‘policiesimplementedbytheendof2020’variesbetweenJuly2019andNovember2020.{WGIIITable4.2,WGIIISPMfootnote25}57Section2ProjectedcumulativefutureCO2emissionsoverthelifetimeofexistingfossilfuelinfrastructurewithoutadditionalabatement95exceedthetotalcumulativenetCO2emissionsinpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot.TheyareapproximatelyequaltototalcumulativenetCO2emissionsinpathwaysthatlimitwarmingto2°Cwithalikelihoodof83%96(seeFigure3.5).Limitingwarmingto2°C(>67%)orlowerwillresultinstrandedassets.About80%ofcoal,50%ofgas,and30%ofoilreservescannotbeburnedandemittedifwarmingislimitedto2°C.Signiﬁcantlymorereservesareexpectedtoremainunburnedifwarmingislimitedto1.5°C.(highconﬁdence){WGIIISPMB.7,WGIIIBox6.3}95AbatementherereferstohumaninterventionsthatreducetheamountofGHGsthatarereleasedfromfossilfuelinfrastructuretotheatmosphere.{WGIIISPMfootnote34}9T6ableW2G.I2pProrvoidjeecstceadrbgolnobbuadlgeemtsisthsaiotnasreinin2li0n3e0waitshsloimciitaintegdglwobitahlwpaorlmiciinegstiomtpemlepmereantutreedlibmyitsthweitehnddiffoefre2n0t2li0kealihnodoNdsD,Csuschananso5u0n%c,e6d7p%rioorr8t3o%C.O{WP2G6I,TaabnldeaSPsMso.2ci}atedemissionsgaps.Emissionsprojectionsfor2030andgrossdifferencesinemissionsarebasedonemissionsof52–56GtCO2-eqyr–1in2019asassumedinunderlyingmodelstudies97.(mediumconﬁdence){WGIIITableSPM.1}(Table3.1,Cross-SectionBox.2)Emissionandimplementationgapsassociatedwithprojectedglobalemissionsin2030underNationallyDeterminedContributions(NDCs)andimplementedpoliciesImpliedbypoliciesImpliedbyNationallyDeterminedContributionsimplementedbytheend(NDCs)announcedpriortoCOP26SectioSnec2tion1of2020(GtCO2-eq/yr)UnconditionalIncludingconditionalelements(GtCO2-eq/yr)elements(GtCO2-eq/yr)Medianprojectedglobalemissions57[52–60]53[50–57]50[47–55](min–max)Implementationgapbetween–implementedpoliciesandNDCs(median)47EmissionsgapbetweenNDCsand–pathwaysthatlimitwarmingto2°C(>67%)withimmediateaction10–166–14EmissionsgapbetweenNDCsandpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimited–19–2616–23overshootwithimmediateactionEmissionsprojectionsfor2030andgrossdifferencesinemissionsarebasedonemissionsof52–56GtCO2-eq/yrin2019asassumedinunderlyingmodelstudies.(mediumconﬁdence)95AbatementherereferstohumaninterventionsthatreducetheamountofGHGsthatarereleasedfromfossilfuelinfrastructuretotheatmosphere.{WGIIISPMfootnote34}96WGIprovidescarbonbudgetsthatareinlinewithlimitingglobalwarmingtotemperaturelimitswithdifferentlikelihoods,suchas50%,67%or83%.{WGITableSPM.2}97The2019rangeofharmonisedGHGemissionsacrossthepathways[53–58GtCO2-eq]iswithintheuncertaintyrangesof2019emissionsassessedinWGIIIChapter2[53–66GtCO2-eq].58CurrentStatusandTrendsProjectedglobalGHGemissionsfromNDCsannouncedpriortoCOP26wouldmakeitlikelythatwarmingwillexceed1.5°Candalsomakeitharderafter2030tolimitwarmingtobelow2°Ca)GlobalGHGemissionsTrendfromimplementedpoliciesb)20307070+5%605060201940GHGemissions(GtCO2-eq/yr)30Limitwarmingto2ºC(>67%)50-4%or1.5(>50%)afterhighovershootwithNDCsuntil2030-26%40-43%Limitwarmingto2ºC(>67%)302020tobeon-tracktolimitwarmingto1.5°C,10Limitwarmingto10weneedmuchmore1.5ºC(>50%)withreductionby2030noorlimitedovershootPastGHGemissionsandSection200uncertaintyfor2015and2019(dotindicatesthemedian)201020152020202520302035204020452050Figure2.5GlobalGHGemissionsofmodelledpathways(funnelsinPanela),andprojectedemissionoutcomesfromnear-termpolicyassessmentsfor2030(Panelb).PanelashowsglobalGHGemissionsover2015-2050forfourtypesofassessedmodelledglobalpathways:-Trendfromimplementedpolicies:Pathwayswithprojectednear-termGHGemissionsinlinewithpoliciesimplementeduntiltheendof2020andextendedwithcomparableambitionlevelsbeyond2030(29scenariosacrosscategoriesC5–C7,WGIIITableSPM.2).-Limitto2°C(>67%)orreturnwarmingto1.5°C(>50%)afterahighovershoot,NDCsuntil2030:PathwayswithGHGemissionsuntil2030associatedwiththeimplementationofNDCsannouncedpriortoCOP26,followedbyacceleratedemissionsreductionslikelytolimitwarmingto2°C(C3b,WGIIITableSPM.2)ortoreturnwarmingto1.5°Cwithaprobabilityof50%orgreaterafterhighovershoot(subsetof42scenariosfromC2,WGIIITableSPM.2).-Limitto2°C(>67%)withimmediateaction:Pathwaysthatlimitwarmingto2°C(>67%)withimmediateactionafter2020(C3a,WGIIITableSPM.2).-Limitto1.5°C(>50%)withnoorlimitedovershoot:Pathwayslimitingwarmingto1.5°Cwithnoorlimitedovershoot(C1,WGIIITableSPM.2C1).Allthesepathwaysassumeimmediateactionafter2020.PastGHGemissionsfor2010-2015usedtoprojectglobalwarmingoutcomesofthemodelledpathwaysareshownbyablackline.PanelbshowsasnapshotoftheGHGemissionrangesofthemodelledpathwaysin2030andprojectedemissionsoutcomesfromnear-termpolicyassessmentsin2030fromWGIIIChapter4.2(Tables4.2and4.3;medianandfullrange).GHGemissionsareCO2-equivalentusingGWP100fromAR6WGI.{WGIIIFigureSPM.4,WGIII3.5,4.2,Table4.2,Table4.3,Cross-ChapterBox4inChapter4}(Table3.1,Cross-SectionBox.2)59SectioSnec2tion1Section2Cross-SectionBox.1:UnderstandingNetZeroCO2andNetZeroGHGEmissionsLimitinghuman-causedglobalwarmingtoaspeciﬁclevelrequireslimitingcumulativeCO2emissions,reachingnetzeroornetnegativeCO2emissions,alongwithstrongreductionsinotherGHGemissions(see3.3.2).Futureadditionalwarmingwilldependonfutureemissions,withtotalwarmingdominatedbypastandfuturecumulativeCO2emissions.{WGISPMD.1.1,WGIFigureSPM.4;SR1.5SPMA.2.2}ReachingnetzeroCO2emissionsisdifferentfromreachingnetzeroGHGemissions.ThetimingofnetzeroforabasketofGHGsdependsontheemissionsmetric,suchasglobalwarmingpotentialovera100-yearperiod,chosentoconvertnon-CO2emissionsintoCO2-equivalent(highconﬁdence).However,foragivenemissionspathway,thephysicalclimateresponseisindependentofthemetricchosen(highconﬁdence).{WGISPMD.1.8;WGIIIBoxTS.6,WGIIICross-ChapterBox2}AchievingglobalnetzeroGHGemissionsrequiresallremainingCO2andmetric-weighted98non-CO2GHGemissionstobecounterbalancedbydurablystoredCO2removals(highconﬁdence).Somenon-CO2emissions,suchasCH4andN2Ofromagriculture,cannotbefullyeliminatedusingexistingandanticipatedtechnicalmeasures.{WGIIISPMC.2.4,WGIIISPMC.11.4,WGIIICross-ChapterBox3}GlobalnetzeroCO2orGHGemissionscanbeachievedevenifsomesectorsandregionsarenetemitters,providedthatothersreachnetnegativeemissions(seeFigure4.1).Thepotentialandcostofachievingnetzeroorevennetnegativeemissionsvarybysectorandregion.Ifandwhennetzeroemissionsforagivensectororregionarereacheddependsonmultiplefactors,includingthepotentialtoreduceGHGemissionsandundertakecarbondioxideremoval,theassociatedcosts,andtheavailabilityofpolicymechanismstobalanceemissionsandremovalsbetweensectorsandcountries.(highconﬁdence){WGIIIBoxTS.6,WGIIICross-ChapterBox3}Theadoptionandimplementationofnetzeroemissiontargetsbycountriesandregionsalsodependonequityandcapacityconsiderations(highconﬁdence).Theformulationofnetzeropathwaysbycountrieswillbeneﬁtfromclarityonscope,plans-of-action,andfairness.Achievingnetzeroemissiontargetsreliesonpolicies,institutions,andmilestonesagainstwhichtotrackprogress.Least-costglobalmodelledpathwayshavebeenshowntodistributethemitigationeffortunevenly,andtheincorporationofequityprinciplescouldchangethecountry-leveltimingofnetzero(highconﬁdence).TheParisAgreementalsorecognizesthatpeakingofemissionswilloccurlaterindevelopingcountriesthandevelopedcountries(Article4.1).{WGIIIBoxTS.6,WGIIICross-ChapterBox3,WGIII14.3}Moreinformationoncountry-levelnetzeropledgesisprovidedinSection2.3.1,onthetimingofglobalnetzeroemissionsinSection3.3.2,andonsectoralaspectsofnetzeroinSection4.1.98Seefootnote12above.60CurrentStatusandTrendsManycountrieshavesignalledanintentiontoachievenet2.3.2.AdaptationGapsandBarriersSection2zeroGHGornetzeroCO2emissionsbyaroundmid-century(Cross-SectionBox.1).Morethan100countrieshaveeitheradopted,Despiteprogress,adaptationgapsexistbetweencurrentannouncedorarediscussingnetzeroGHGornetzeroCO2emissionslevelsofadaptationandlevelsneededtorespondtoimpactscommitments,coveringmorethantwo-thirdsofglobalGHGemissions.andreduceclimaterisks(highconﬁdence).WhileprogressinAgrowingnumberofcitiesaresettingclimatetargets,includingnetzeroadaptationimplementationisobservedacrossallsectorsandregionsGHGtargets.Manycompaniesandinstitutionshavealsoannounced(veryhighconﬁdence),manyadaptationinitiativesprioritiseimmediatenetzeroemissionstargetsinrecentyears.Thevariousnetzeroemissionandnear-termclimateriskreduction,e.g.,throughhardﬂoodprotection,pledgesdifferacrosscountriesintermsofscopeandspeciﬁcity,andwhichreducestheopportunityfortransformationaladaptation99(highlimitedpoliciesaretodateinplacetodeliveronthem.{WGIIISPMC.6.4,conﬁdence).Mostobservedadaptationisfragmented,smallinscale,WGIIITS.4.1,WGIIITableTS.1,WGIII13.9,WGIII14.3,WGIII14.5}incremental,sector-speciﬁc,andfocusedmoreonplanningratherthanimplementation(highconﬁdence).Further,observedadaptationisAllmitigationstrategiesfaceimplementationchallenges,unequallydistributedacrossregionsandthelargestadaptationgapsincludingtechnologyrisks,scaling,andcosts(highconﬁdence).existamonglowerpopulationincomegroups(highconﬁdence).IntheAlmostallmitigationoptionsalsofaceinstitutionalbarriersthaturbancontext,thelargestadaptationgapsexistinprojectsthatmanageneedtobeaddressedtoenabletheirapplicationatscale(mediumcomplexrisks,forexampleinthefood–energy–water–healthnexusorconﬁdence).Currentdevelopmentpathwaysmaycreatebehavioural,theinter-relationshipsofairqualityandclimaterisk(highconﬁdence).spatial,economicandsocialbarrierstoacceleratedmitigationatallManyfunding,knowledgeandpracticegapsremainforeffectivescales(highconﬁdence).Choicesmadebypolicymakers,citizens,theimplementation,monitoringandevaluationandcurrentadaptationprivatesectorandotherstakeholdersinﬂuencesocieties’developmenteffortsarenotexpectedtomeetexistinggoals(highconﬁdence).pathways(highconﬁdence).StructuralfactorsofnationalcircumstancesAtcurrentratesofadaptationplanningandimplementationtheandcapabilities(e.g.,economicandnaturalendowments,politicaladaptationgapwillcontinuetogrow(highconﬁdence).{WGIISPMC.1,systemsandculturalfactorsandgenderconsiderations)affecttheWGIISPMC.1.2,WGIISPMC.4.1,WGIITS.D.1.3,WGIITS.D.1.4}breadthanddepthofclimategovernance(mediumconﬁdence).Theextenttowhichcivilsocietyactors,politicalactors,businesses,youth,Softandhardadaptationlimits100havealreadybeenreachedinlabour,media,IndigenousPeoples,andlocalcommunitiesareengagedsomesectorsandregions,inspiteofadaptationhavingbufferedinﬂuencespoliticalsupportforclimatechangemitigationandeventualsomeclimateimpacts(highconﬁdence).Ecosystemsalreadypolicyoutcomes(mediumconﬁdence).{WGIIISPMC.3.6,WGIIISPME.1.1,reachinghardadaptationlimitsincludesomewarmwatercoralreefs,WGIIISPME.2.1,WGIIISPME.3.3}somecoastalwetlands,somerainforests,andsomepolarandmountainecosystems(highconﬁdence).IndividualsandhouseholdsinlowlyingTheadoptionoflow-emissiontechnologieslagsinmostcoastalareasinAustralasiaandSmallIslandsandsmallholderfarmersdevelopingcountries,particularlyleastdevelopedones,inCentralandSouthAmerica,Africa,EuropeandAsiahavereacheddueinparttoweakerenablingconditions,includinglimitedsoftlimits(mediumconﬁdence),resultingfromﬁnancial,governance,ﬁnance,technologydevelopmentandtransfer,andcapacityinstitutionalandpolicyconstraintsandcanbeovercomebyaddressing(mediumconﬁdence).Inmanycountries,especiallythosewiththeseconstraints(highconﬁdence).Transitioningfromincrementaltolimitedinstitutionalcapacity,severaladverseside-effectshavetransformationaladaptationcanhelpovercomesoftadaptationlimitsbeenobservedasaresultofdiffusionoflow-emissiontechnology,(highconﬁdence).{WGIISPMC.3,WGIISPMC.3.1,WGIISPMC.3.2,e.g.,low-valueemployment,anddependencyonforeignknowledgeWGIISPMC.3.3,WGIISPM.C.3.4,WGII16ES}andsuppliers(mediumconﬁdence).Low-emissioninnovationalongwithstrengthenedenablingconditionscanreinforcedevelopmentAdaptationdoesnotpreventalllossesanddamages,evenwithbeneﬁts,whichcan,inturn,createfeedbackstowardsgreaterpubliceffectiveadaptationandbeforereachingsoftandhardlimits.Lossessupportforpolicy(mediumconﬁdence).Persistentandregion-speciﬁcanddamagesareunequallydistributedacrosssystems,regionsandbarriersalsocontinuetohampertheeconomicandpoliticalfeasibilitysectorsandarenotcomprehensivelyaddressedbycurrentﬁnancial,ofdeployingAFOLUmitigationoptions(mediumconﬁdence).Barrierstogovernanceandinstitutionalarrangements,particularlyinvulnerableimplementationofAFOLUmitigationincludeinsufﬁcientinstitutionalanddevelopingcountries.(highconﬁdence){WGIISPM.C.3.5}ﬁnancialsupport,uncertaintyoverlong-termadditionalityandtrade-offs,weakgovernance,insecurelandownership,lowincomesandthelackThereisincreasedevidenceofmaladaptation101invarioussectorsofaccesstoalternativesourcesofincome,andtheriskofreversal(highandregions.Examplesofmaladaptationareobservedinurbanareasconﬁdence).{WGIIISPMB.4.2,WGIIISPMC.9.1,WGIIISPMC.9.3}(e.g.,newurbaninfrastructurethatcannotbeadjustedeasilyoraffordably),agriculture(e.g.,usinghigh-costirrigationinareasprojectedtohavemoreintensedroughtconditions),ecosystems(e.g.ﬁresuppressioninnaturally99SeeAnnexI:Glossary.100Adaptationlimit:Thepointatwhichanactor’sobjectives(orsystemneeds)cannotbesecuredfromintolerablerisksthroughadaptiveactions.Hardadaptationlimit-Noadaptiveactionsarepossibletoavoidintolerablerisks.Softadaptationlimit-Optionsarecurrentlynotavailabletoavoidintolerablerisksthroughadaptiveaction.101Maladaptationreferstoactionsthatmayleadtoincreasedriskofadverseclimate-relatedoutcomes,includingviaincreasedgreenhousegasemissions,increasedorshiftedvulnerabilitytoclimatechange,moreinequitableoutcomes,ordiminishedwelfare,noworinthefuture.Mostoften,maladaptationisanunintendedconsequence.SeeAnnexI:Glossary.61Section2SectioSnec2tion1ﬁre-adaptedecosystems,orharddefencesagainstﬂooding)andhumanintegrityandadditionality,aswellasthelimitedapplicabilityofsettlements(e.g.strandedassetsandvulnerablecommunitiesthatthesemarketstomanydevelopingcountries(highconfidence).cannotaffordtoshiftawayoradaptandrequireanincreaseinsocial{WGIISPMC.3.2,WGIISPMC.5.4;WGIIISPMB.5.4,WGIIISPME.5.1}safetynets).Maladaptationespeciallyaffectsmarginalisedandvulnerablegroupsadversely(e.g.,IndigenousPeoples,ethnicminorities,low-incomeCurrentglobalﬁnancialﬂowsforadaptationincludingfrompublichouseholds,peoplelivingininformalsettlements),reinforcingandandprivateﬁnancesources,areinsufﬁcientforandconstrainentrenchingexistinginequities.Maladaptationcanbeavoidedbyﬂexible,implementationofadaptationoptions,especiallyindevelopingmulti-sectoral,inclusiveandlong-termplanningandimplementationofcountries(highconﬁdence).Therearewideningdisparitiesbetweenadaptationactionswithbeneﬁtstomanysectorsandsystems.(hightheestimatedcostsofadaptationandthedocumentedﬁnanceconﬁdence){WGIISPMC.4,WGIISPMC.4.3,WGIITS.D.3.1}allocatedtoadaptation(highconﬁdence).AdaptationﬁnanceneedsareestimatedtobehigherthanthoseassessedinAR5,andSystemicbarriersconstraintheimplementationofadaptationtheenhancedmobilisationofandaccesstoﬁnancialresourcesareoptionsinvulnerablesectors,regionsandsocialgroups(highessentialforimplementationofadaptationandtoreduceadaptationconﬁdence).Keybarriersincludelimitedresources,lackofprivate-sectorgaps(highconﬁdence).Annualﬁnanceﬂowstargetingadaptationforandcivicengagement,insufﬁcientmobilisationofﬁnance,lackofpoliticalAfrica,forexample,arebillionsofUSDlessthanthelowestadaptationcommitment,limitedresearchand/orslowandlowuptakeofadaptationcostestimatesfornear-termclimatechange(highconﬁdence).Adversescienceandalowsenseofurgency.Inequityandpovertyalsoconstrainclimateimpactscanfurtherreducetheavailabilityofﬁnancialresourcesadaptation,leadingtosoftlimitsandresultingindisproportionatebycausinglossesanddamagesandimpedingnationaleconomicexposureandimpactsformostvulnerablegroups(highconﬁdence).Thegrowth,therebyfurtherincreasingﬁnancialconstraintsforadaptationlargestadaptationgapsexistamonglowerincomepopulationgroupsparticularlyfordevelopingcountriesandLDCs(mediumconﬁdence).(highconﬁdence).Asadaptationoptionsoftenhavelongimplementation{WGIISPMC.1.2,WGIISPMC.3.2,WGIISPMC.5.4,WGIITS.D.1.6}times,long-termplanningandacceleratedimplementation,particularlyinthisdecade,isimportanttocloseadaptationgaps,recognisingthatWithouteffectivemitigationandadaptation,lossesanddamageswillconstraintsremainforsomeregions(highconﬁdence).Prioritisationofcontinuetodisproportionatelyaffectthepoorestandmostvulnerableoptionsandtransitionsfromincrementaltotransformationaladaptationpopulations.Acceleratedﬁnancialsupportfordevelopingcountriesarelimitedduetovestedinterests,economiclock-ins,institutionalfromdevelopedcountriesandothersourcesisacriticalenablertopathdependenciesandprevalentpractices,cultures,normsandbeliefenhancemitigationaction{WGIIISPM.E.5.3}.Manydevelopingsystems(highconﬁdence).Manyfunding,knowledgeandpracticecountrieslackcomprehensivedataatthescaleneededandlackadequategapsremainforeffectiveimplementation,monitoringandevaluationﬁnancialresourcesneededforadaptationforreducingassociatedofadaptation(highconﬁdence),including,lackofclimateliteracyateconomicandnon-economiclossesanddamages.(highconﬁdence)alllevelsandlimitedavailabilityofdataandinformation(medium{WGIICross-ChapterBoxLOSS,WGIISPMC.3.1,WGIISPMC.3.2,conﬁdence);forexampleforAfrica,severeclimatedataconstraintsandWGIITS.D.1.3,WGIITS.D.1.5;WGIIISPME.5.3}inequitiesinresearchfundingandleadershipreduceadaptivecapacity(veryhighconﬁdence).{WGIISPMC.1.2,WGIISPMC.3.1,WGIITS.D.1.3,TherearebarrierstoredirectingcapitaltowardsclimateactionbothWGIITS.D.1.5,WGIITS.D.2.4}withinandoutsidetheglobalﬁnancialsector.Thesebarriersinclude:theinadequateassessmentofclimate-relatedrisksandinvestment2.3.3.LackofFinanceasaBarriertoClimateActionopportunities,regionalmismatchbetweenavailablecapitalandinvestmentneeds,homebiasfactors,countryindebtednesslevels,Insufﬁcientﬁnancing,andalackofpoliticalframeworksandeconomicvulnerability,andlimitedinstitutionalcapacities.Challengesincentivesforﬁnance,arekeycausesoftheimplementationfromoutsidetheﬁnancialsectorinclude:limitedlocalcapitalmarkets;gapsforbothmitigationandadaptation(highconﬁdence).unattractiverisk-returnproﬁles,inparticularduetomissingorweakFinancialﬂowsremainedheavilyfocusedonmitigation,areregulatoryenvironmentsthatareinconsistentwithambitionlevels;uneven,andhavedevelopedheterogeneouslyacrossregionslimitedinstitutionalcapacitytoensuresafeguards;standardisation,andsectors(highconﬁdence).In2018,publicandpubliclymobilisedaggregation,scalabilityandreplicabilityofinvestmentopportunitiesprivateclimateﬁnanceﬂowsfromdevelopedtodevelopingcountriesandﬁnancingmodels;and,apipelinereadyforcommercialinvestments.werebelowthecollectivegoalundertheUNFCCCandParisAgreement(highconﬁdence){WGIISPMC.5.4;WGIIISPME.5.2;SR1.5SPMD.5.2}tomobiliseUSD100billionperyearby2020inthecontextofmeaningfulmitigationactionandtransparencyonimplementation(mediumconﬁdence).Publicandprivateﬁnanceﬂowsforfossilfuelsarestillgreaterthanthoseforclimateadaptationandmitigation(highconﬁdence).Theoverwhelmingmajorityoftrackedclimateﬁnanceisdirectedtowardsmitigation(veryhighconﬁdence).Nevertheless,averageannualmodelledinvestmentrequirementsfor2020to2030inscenariosthatlimitwarmingto2°Cor1.5°Careafactorofthreetosixgreaterthancurrentlevels,andtotalmitigationinvestments(public,private,domesticandinternational)wouldneedtoincreaseacrossallsectorsandregions(mediumconﬁdence).Challengesremainforgreenbondsandsimilarproducts,inparticulararound62CurrentStatusandTrendsSection2Cross-SectionBox.2:Scenarios,GlobalWarmingLevels,andRisksModelledscenariosandpathways102areusedtoexplorefutureemissions,climatechange,relatedimpactsandrisks,andpossiblemitigationandadaptationstrategiesandarebasedonarangeofassumptions,includingsocio-economicvariablesandmitigationoptions.Thesearequantitativeprojectionsandareneitherpredictionsnorforecasts.Globalmodelledemissionpathways,includingthosebasedoncosteffectiveapproachescontainregionallydifferentiatedassumptionsandoutcomes,andhavetobeassessedwiththecarefulrecognitionoftheseassumptions.Mostdonotmakeexplicitassumptionsaboutglobalequity,environmentaljusticeorintra-regionalincomedistribution.IPCCisneutralwithregardtotheassumptionsunderlyingthescenariosintheliteratureassessedinthisreport,whichdonotcoverallpossiblefutures103.{WGIBoxSPM.1;WGIIBoxSPM.1;WGIIIBoxSPM.1;SROCCBoxSPM.1;SRCCLBoxSPM.1}Socio-economicDevelopment,Scenarios,andPathwaysTheﬁveSharedSocio-economicPathways(SSP1toSSP5)weredesignedtospanarangeofchallengestoclimatechangemitigationandadaptation.Fortheassessmentofclimateimpacts,riskandadaptation,theSSPsareusedforfutureexposure,vulnerabilityandchallengestoadaptation.DependingonlevelsofGHGmitigation,modelledemissionsscenariosbasedontheSSPscanbeconsistentwithloworhighwarminglevels104.Therearemanydifferentmitigationstrategiesthatcouldbeconsistentwithdifferentlevelsofglobalwarmingin2100(seeFigure4.1).{WGIBoxSPM.1;WGIIBoxSPM.1;WGIIIBoxSPM.1,WGIIIBoxTS.5,WGIIIAnnexIII;SRCCLBoxSPM.1,SRCCLFigureSPM.2}WGIassessedtheclimateresponsetoﬁveillustrativescenariosbasedonSSPs105thatcovertherangeofpossiblefuturedevelopmentofanthropogenicdriversofclimatechangefoundintheliterature.Thesescenarioscombinesocio-economicassumptions,levelsofclimatemitigation,landuseandairpollutioncontrolsforaerosolsandnon-CH4ozoneprecursors.ThehighandveryhighGHGemissionsscenarios(SSP3-7.0andSSP5-8.5)haveCO2emissionsthatroughlydoublefromcurrentlevelsby2100and2050,respectively106.TheintermediateGHGemissionsscenario(SSP2-4.5)hasCO2emissionsremainingaroundcurrentlevelsuntilthemiddleofthecentury.TheverylowandlowGHGemissionsscenarios(SSP1-1.9andSSP1-2.6)haveCO2emissionsdecliningtonetzeroaround2050and2070,respectively,followedbyvaryinglevelsofnetnegativeCO2emissions.Inaddition,RepresentativeConcentrationPathways(RCPs)107wereusedbyWGIandWGIItoassessregionalclimatechanges,impactsandrisks.{WGIBoxSPM.1}(Cross-SectionBox.2Figure1)InWGIII,alargenumberofglobalmodelledemissionspathwayswereassessed,ofwhich1202pathwayswerecategorisedbasedontheirprojectedglobalwarmingoverthe21stcentury,withcategoriesrangingfrompathwaysthatlimitwarmingto1.5°Cwithmorethan50%likelihood108withnoorlimitedovershoot(C1)topathwaysthatexceed4°C(C8).MethodstoprojectglobalwarmingassociatedwiththemodelledpathwayswereupdatedtoensureconsistencywiththeAR6WGIassessmentoftheclimatesystemresponse109.{WGIIIBoxSPM.1,WGIIITable3.1}(Table3.1,Cross-SectionBox.2Figure1)102Intheliterature,thetermspathwaysandscenariosareusedinterchangeably,withtheformermorefrequentlyusedinrelationtoclimategoals.WGIprimarilyusedthetermscenariosandWGIIImostlyusedthetermmodelledemissionsandmitigationpathways.TheSYRprimarilyusesscenarioswhenreferringtoWGIandmodelledemissionsandmitigationpathwayswhenreferringtoWGIII.{WGIBoxSPM.1;WGIIIfootnote44}103Aroundhalfofallmodelledglobalemissionspathwaysassumecost-effectiveapproachesthatrelyonleast-costmitigation/abatementoptionsglobally.Theotherhalflookatexistingpoliciesandregionallyandsectorallydifferentiatedactions.Theunderlyingpopulationassumptionsrangefrom8.5to9.7billionin2050and7.4to10.9billionin2100(5–95thpercentile)startingfrom7.6billionin2019.TheunderlyingassumptionsonglobalGDPgrowthrangefrom2.5to3.5%peryearinthe2019–2050periodand1.3to2.1%peryearinthe2050–2100(5–95thpercentile).{WGIIIBoxSPM.1}104Highmitigationchallenges,forexample,duetoassumptionsofslowtechnologicalchange,highlevelsofglobalpopulationgrowth,andhighfragmentationasintheSharedSocio-economicPathwaySSP3,mayrendermodelledpathwaysthatlimitwarmingto2°C(>67%)orlowerinfeasible(mediumconﬁdence).{WGIIISPMC.1.4;SRCCLBoxSPM.1}105SSP-basedscenariosarereferredtoasSSPx-y,where‘SSPx’referstotheSharedSocio-economicPathwaydescribingthesocioeconomictrendsunderlyingthescenarios,and‘y’referstothelevelofradiativeforcing(inwattspersquaremetre,orWm–2)resultingfromthescenariointheyear2100.{WGISPMfootnote22}106Veryhighemissionscenarioshavebecomelesslikelybutcannotberuledout.Temperaturelevels>4°Cmayresultfromveryhighemissionscenarios,butcanalsooccurfromloweremissionscenariosifclimatesensitivityorcarboncyclefeedbacksarehigherthanthebestestimate.{WGIIISPMC.1.3}107RCP-basedscenariosarereferredtoasRCPy,where‘y’referstotheapproximatelevelofradiativeforcing(inwattspersquaremetre,orWm–2)resultingfromthescenariointheyear2100.{WGIISPMfootnote21}108Denoted‘>50%’inthisreport.109Theclimateresponsetoemissionsisinvestigatedwithclimatemodels,paleoclimaticinsightsandotherlinesofevidence.Theassessmentoutcomesareusedtocategorisethousandsofscenariosviasimplephysically-basedclimatemodels(emulators).{WGITS.1.2.2}63SectioSnec2tion1Section2GlobalWarmingLevels(GWLs)Formanyclimateandriskvariables,thegeographicalpatternsofchangesinclimaticimpact-drivers110andclimateimpactsforalevelofglobalwarming111arecommontoallscenariosconsideredandindependentoftimingwhenthatlevelisreached.ThismotivatestheuseofGWLsasadimensionofintegration.{WGIBoxSPM.1.4,WGITS.1.3.2;WGIIBoxSPM.1}(Figure3.1,Figure3.2)RisksDynamicinteractionsbetweenclimate-relatedhazards,exposureandvulnerabilityoftheaffectedhumansociety,species,orecosystemsresultinrisksarisingfromclimatechange.AR6assesseskeyrisksacrosssectorsandregionsaswellasprovidinganupdatedassessmentoftheReasonsforConcern(RFCs)–ﬁvegloballyaggregatedcategoriesofriskthatevaluateriskaccrualwithincreasingglobalsurfacetemperature.Riskscanalsoarisefromclimatechangemitigationoradaptationresponseswhentheresponsedoesnotachieveitsintendedobjective,orwhenitresultsinadverseeffectsforothersocietalobjectives.{WGIISPMA,WGIIFigureSPM.3,WGIIBoxTS.1,WGIIFigureTS.4;SR1.5FigureSPM.2;SROCCErrataFigureSPM.3;SRCCLFigureSPM.2}(3.1.2,Cross-SectionBox.2Figure1,Figure3.3)110SeeAnnexI:Glossary111SeeAnnexI:Glossary.Here,globalwarmingisthe20-yearaverageglobalsurfacetemperaturerelativeto1850–1900.Theassessedtimeofwhenacertainglobalwarminglevelisreachedunderaparticularscenarioisdeﬁnedhereasthemid-pointoftheﬁrst20-yearrunningaverageperiodduringwhichtheassessedaverageglobalsurfacetemperaturechangeexceedsthelevelofglobalwarming.{WGISPMfootnote26,Cross-SectionBoxTS.1}64CurrentStatusandTrendsScenariosandwarminglevelsstructureourunderstandingacrossthecause-effectchainfromemissionstoclimatechangeandrisksa)AR6integratedassessmentframeworkonfutureclimate,impactsandmitigationSocio-economicchangesshapeinﬂuenceinﬂuenceEmissionsthatchangeClimatewhichdrivesImpacts/RisksMitigationPolicyAdaptationPolicyCO2emissionsforSSP-basedscenariosTemperatureforSSP-basedscenariosovertheRisksandC1-C8categories21stcenturyandC1-C8at2100canberepresentedascolorshadingshowsSSP5-8.5°C7“burningembers”C1-C8categorySSP3-7.01006RFC1UniqueandcolorshadingshowsthreatenedsystemsrangeforSSP3-7.0°C55andSSP1-2.6SSP5-8.543GtCO2/yr4SSP3-7.021increasingrisk5003SSP2-4.52SSP1-2.60SSP2-4.51SSP1-1.92050SSP1-2.6SSP1-1.9020502100C1-C8in21002100b)ScenariosandpathwaysacrossAR6WorkingGroupreportsc)DeterminantsofriskSection2CategoryCategorydescriptionGHGemissionsscenariosRCPyinClimaticVulnerabilityinWGIII(SSPx-y)inWGI&WGIIWGI&WGIIImpact-limitwarmingto1.5°C(>50%)Verylow(SSP1-1.9)DriversC1withnoorlimitedovershootRCP2.6returnwarmingto1.5°C(>50%)Low(SSP1-2.6)RCP4.5HazardRiskExposureC2afterahighovershootRCP8.5limitwarmingto2°C(>67%)Intermediate(SSP2-4.5)ResponseC3limitwarmingto2°C(>50%)High(SSP3-7.0)C4limitwarmingto2.5°C(>50%)Veryhigh(SSP5-8.5)C5limitwarmingto3°C(>50%)C6limitwarmingto4°C(>50%)C7exceedwarmingof4°C(>50%)C8TheterminologySSPx-yisused,where‘SSPx’referstotheSharedSocio-economicPathwayor‘SSP’describingthesocio-economictrendsunderlyingthescenario,and‘y’referstotheapproximatelevelofradiativeforcing(inwattspersquaremetre,orWm–2)resultingfromthescenariointheyear2100.TheAR5scenarios(RCPy),whichpartlyinformtheAR6WGIandWGIIassessments,areindexedtoasimilarsetofapproximate2100radiativeforcinglevels(inWm-2).TheSSPscenarioscoverabroaderrangeofGHGandairpollutantfuturesthantheRCPs.Theyaresimilarbutnotidentical,withdifferencesinconcentrationtrajectoriesfordifferentGHGs.TheoverallradiativeforcingtendstobehigherfortheSSPscomparedtotheRCPswiththesamelabel(mediumconﬁdence).{WGITS.1.3.1}Limitedovershootreferstoexceeding1.5°Cglobalwarmingbyuptoabout0.1°C,highovershootby0.1°C-0.3°C,inbothcasesforuptoseveraldecades.65SectioSnec2tion1Section2Cross-SectionBox.2Figure1:SchematicoftheAR6frameworkforassessingfuturegreenhousegasemissions,climatechange,risks,impactsandmitigation.Panel(a)Theintegratedframeworkencompassessocio-economicdevelopmentandpolicy,emissionspathwaysandglobalsurfacetemperatureresponsestotheﬁvescenariosconsideredbyWGI(SSP1-1.9,SSP1-2.6,SSP2-4.5,SSP3-7.0,andSSP5-8.5)andeightglobalmeantemperaturechangecategorisations(C1–C8)assessedbyWGIII,andtheWGIIriskassessment.Thedashedarrowindicatesthattheinﬂuencefromimpacts/riskstosocio-economicchangesisnotyetconsideredinthescenariosassessedintheAR6.EmissionsincludeGHGs,aerosols,andozoneprecursors.CO2emissionsareshownasanexampleontheleft.Theassessedglobalsurfacetemperaturechangesacrossthe21stcenturyrelativeto1850-1900fortheﬁveGHGemissionsscenariosareshownasanexampleinthecentre.VerylikelyrangesareshownforSSP1-2.6andSSP3-7.0.Projectedtemperatureoutcomesat2100relativeto1850-1900areshownforC1toC8categorieswithmedian(line)andthecombinedverylikelyrangeacrossscenarios(bar).Ontheright,futurerisksduetoincreasingwarmingarerepresentedbyanexample‘burningember’ﬁgure(see3.1.2forthedeﬁnitionofRFC1).Panel(b)DescriptionandrelationshipofscenariosconsideredacrossAR6WorkingGroupreports.Panel(c)Illustrationofriskarisingfromtheinteractionofhazard(drivenbychangesinclimaticimpact-drivers)withvulnerability,exposureandresponsetoclimatechange.{WGITS1.4,Figure4.11;WGIIFigure1.5,WGIIFigure14.8;WGIIITableSPM.2,WGIIIFigure3.11}66Section3Long-TermClimateandDevelopmentFutures67Section3Section3:Long-TermClimateandDevelopmentFutures3.1Long-TermClimateChange,ImpactsandRelatedRisksFuturewarmingwillbedrivenbyfutureemissionsandwillaffectallmajorclimatesystemcomponents,witheveryregionexperiencingmultipleandco-occurringchanges.Manyclimate-relatedrisksareassessedtobehigherthaninpreviousassessments,andprojectedlong-termimpactsareuptomultipletimeshigherthancurrentlyobserved.Multipleclimaticandnon-climaticriskswillinteract,resultingincompoundingandcascadingrisksacrosssectorsandregions.Sealevelrise,aswellasotherirreversiblechanges,willcontinueforthousandsofyears,atratesdependingonfutureemissions.(highconﬁdence)SectioSnec3tion13.1.1.Long-termClimateChangeGlobalwarmingwillcontinuetoincreaseinthenearterminnearlyallconsideredscenariosandmodelledpathways.Deep,Theuncertaintyrangeonassessedfuturechangesinglobalrapid,andsustainedGHGemissionsreductions,reachingnetsurfacetemperatureisnarrowerthanintheAR5.FortheﬁrstzeroCO2emissionsandincludingstrongemissionsreductionstimeinanIPCCassessmentcycle,multi-modelprojectionsofglobalofotherGHGs,inparticularCH4,arenecessarytolimitwarmingsurfacetemperature,oceanwarmingandsealevelareconstrainedto1.5°C(>50%)orlessthan2°C(>67%)bytheendofcenturyusingobservationsandtheassessedclimatesensitivity.Thelikely(highconﬁdence).Thebestestimateofreaching1.5°Cofglobalrangeofequilibriumclimatesensitivityhasbeennarrowedto2.5°Cwarmingliesintheﬁrsthalfofthe2030sinmostoftheconsideredto4.0°C(withabestestimateof3.0°C)basedonmultiplelinesofscenariosandmodelledpathways114.IntheverylowGHGemissionsevidence112,includingimprovedunderstandingofcloudfeedbacks.Forscenario(SSP1-1.9),CO2emissionsreachnetzeroaround2050andtherelatedemissionsscenarios,thisleadstonarroweruncertaintyrangesbest-estimateend-of-centurywarmingis1.4°C,afteratemporaryovershootforlong-termprojectedglobaltemperaturechangethaninAR5.(seeSection3.3.4)ofnomorethan0.1°Cabove1.5°Cglobalwarming.{WGIA.4,WGIBoxSPM.1,WGITS.3.2,WGI4.3}Globalwarmingof2°Cwillbeexceededduringthe21stcenturyunlessdeepreductionsinCO2andotherGHGemissionsoccurinthecomingFuturewarmingdependsonfutureGHGemissions,withdecades.Deep,rapid,andsustainedreductionsinGHGemissionswouldcumulativenetCO2dominating.Theassessedbestestimatesandleadtoimprovementsinairqualitywithinafewyears,toreductionsinverylikelyrangesofwarmingfor2081-2100withrespectto1850–1900trendsofglobalsurfacetemperaturediscernibleafteraround20years,varyfrom1.4[1.0to1.8]°CintheverylowGHGemissionsscenarioandoverlongertimeperiodsformanyotherclimateimpact-drivers115(SSP1-1.9)to2.7[2.1to3.5]°CintheintermediateGHGemissions(highconﬁdence).Targetedreductionsofairpollutantemissionsleadscenario(SSP2-4.5)and4.4[3.3to5.7]°CintheveryhighGHGemissionstomorerapidimprovementsinairqualitycomparedtoreductionsscenario(SSP5-8.5)113.{WGISPMB.1.1,WGITableSPM.1,WGIFigureinGHGemissionsonly,butinthelongterm,furtherimprovementsareSPM.4}(Cross-SectionBox.2Figure1)projectedinscenariosthatcombineeffortstoreduceairpollutantsaswellasGHGemissions(highconﬁdence)116.{WGISPMB.1,WGISPMB.1.3,ModelledpathwaysconsistentwiththecontinuationofpoliciesWGISPMD.1,WGISPMD.2,WGIFigureSPM.4,WGITableSPM.1,implementedbytheendof2020leadtoglobalwarmingofWGICross-SectionBoxTS.1;WGIIISPMC.3,WGIIITableSPM.2,3.2[2.2to3.5]°C(5–95%range)by2100(mediumconﬁdence)WGIIIFigureSPM.5,WGIIIBoxSPM.1Figure1,WGIIITable3.2}(Table3.1,(seealsoSection2.3.1).Pathwaysof>4°C(≥50%)by2100wouldCross-SectionBox.2Figure1)implyareversalofcurrenttechnologyand/ormitigationpolicytrends(mediumconﬁdence).However,suchwarmingcouldoccurinemissionsChangesinshort-livedclimateforcers(SLCF)resultingfromthepathwaysconsistentwithpoliciesimplementedbytheendof2020ifﬁveconsideredscenariosleadtoanadditionalnetglobalwarmingclimatesensitivityorcarboncyclefeedbacksarehigherthanthebestinthenearandlongterm(highconﬁdence).Simultaneousestimate(highconﬁdence).{WGIIISPMC.1.3}stringentclimatechangemitigationandairpollutioncontrol112Understandingofclimateprocesses,theinstrumentalrecord,paleoclimatesandmodel-basedemergentconstraints(seeAnnexI:Glossary).{WGISPMfootnote21}113Thebestestimates[andverylikelyranges]forthedifferentscenariosare:1.4[1.0to1.8]°C(SSP1-1.9);1.8[1.3to2.4]°C(SSP1-2.6);2.7[2.1to3.5]°C(SSP2-4.5);3.6[2.8to4.6]°C(SSP3-7.0);and4.4[3.3to5.7]°C(SSP5-8.5).{WGITableSPM.1}(Cross-SectionBox.2)114Inthenearterm(2021–2040),the1.5°CglobalwarminglevelisverylikelytobeexceededundertheveryhighGHGemissionsscenario(SSP5-8.5),likelytobeexceededundertheintermediateandhighGHGemissionsscenarios(SSP2-4.5,SSP3-7.0),morelikelythannottobeexceededunderthelowGHGemissionsscenario(SSP1-2.6)andmorelikelythannottobereachedundertheverylowGHGemissionsscenario(SSP1-1.9).InallscenariosconsideredbyWGIexcepttheveryhighemissionsscenario,themidpointoftheﬁrst20-yearrunningaverageperiodduringwhichtheassessedglobalwarmingreaches1.5°Cliesintheﬁrsthalfofthe2030s.IntheveryhighGHGemissionsscenario,thismid-pointisinthelate2020s.Themedianﬁve-yearintervalatwhicha1.5°Cglobalwarminglevelisreached(50%probability)incategoriesofmodelledpathwaysconsideredinWGIIIis2030–2035.{WGISPMB.1.3,WGICross-SectionBoxTS.1,WGIIITable3.2}(Cross-SectionBox.2)115SeeCross-SectionBox.2.116Basedonadditionalscenarios.68Long-TermClimateandDevelopmentFuturespolicieslimitthisadditionalwarmingandleadtostrongbeneﬁtsintensificationoftropicalcyclonesand/orextratropicalstorms(mediumconﬁdence),andincreasesinaridityandﬁreweather119forairquality(highconﬁdence).InhighandveryhighGHG(mediumtohighconﬁdence).Compoundheatwavesanddroughtsemissionsscenarios(SSP3-7.0andSSP5-8.5),combinedchangesbecomelikelymorefrequent,includingconcurrentlyatmultipleinSLCFemissions,suchasCH4,aerosolandozoneprecursors,leadtoalocations(highconﬁdence).{WGISPMC.2,WGISPMC.2.1,WGISPMC.2.2,netglobalwarmingby2100oflikely0.4°Cto0.9°Crelativeto2019.WGISPMC.2.3,WGISPMC.2.4,WGISPMC.2.7}ThisisduetoprojectedincreasesinatmosphericconcentrationofCH4,troposphericozone,hydroﬂuorocarbonsand,whenstrongairpollutioncontrolisconsidered,reductionsofcoolingaerosols.InlowandverylowGHGemissionsscenarios(SSP1-1.9andSSP1-2.6),airpollutioncontrolpolicies,reductionsinCH4andotherozoneprecursorsleadtoanetcooling,whereasreductionsinanthropogeniccoolingaerosolsleadtoanetwarming(highconﬁdence).Altogether,thiscausesalikelynetwarmingof0.0°Cto0.3°CduetoSLCFchangesin2100relativeto2019andstrongreductionsinglobalsurfaceozoneandparticulatematter(highconﬁdence).{WGISPMD.1.7,WGIBoxTS.7}(Cross-SectionBox.2)ContinuedGHGemissionswillfurtheraffectallmajorclimateSection3systemcomponents,andmanychangeswillbeirreversibleoncentennialtomillennialtimescales.Manychangesintheclimatesystembecomelargerindirectrelationtoincreasingglobalwarming.Witheveryadditionalincrementofglobalwarming,changesinextremescontinuetobecomelarger.Additionalwarmingwillleadtomorefrequentandintensemarineheatwavesandisprojectedtofurtheramplifypermafrostthawingandlossofseasonalsnowcover,glaciers,landiceandArcticseaice(highconﬁdence).Continuedglobalwarmingisprojectedtofurtherintensifytheglobalwatercycle,includingitsvariability,globalmonsoonprecipitation117,andverywetandverydryweatherandclimateeventsandseasons(highconﬁdence).Theportionofgloballandexperiencingdetectablechangesinseasonalmeanprecipitationisprojectedtoincrease(mediumconﬁdence)withmorevariableprecipitationandsurfacewaterﬂowsovermostlandregionswithinseasons(highconﬁdence)andfromyeartoyear(mediumconﬁdence).ManychangesduetopastandfutureGHGemissionsareirreversible118oncentennialtomillennialtimescales,especiallyintheocean,icesheetsandglobalsealevel(see3.1.3).Oceanacidiﬁcation(virtuallycertain),oceandeoxygenation(highconﬁdence)andglobalmeansealevel(virtuallycertain)willcontinuetoincreaseinthe21stcentury,atratesdependentonfutureemissions.{WGISPMB.2,WGISPMB.2.2,WGISPMB.2.3,WGISPMB.2.5,WGISPMB.3,WGISPMB.3.1,WGISPMB.3.2,WGISPMB.4,WGISPMB.5,WGISPMB.5.1,WGISPMB.5.3,WGIFigureSPM.8}(Figure3.1)Withfurtherglobalwarming,everyregionisprojectedtoincreasinglyexperienceconcurrentandmultiplechangesinclimaticimpact-drivers.Increasesinhotanddecreasesincoldclimaticimpact-drivers,suchastemperatureextremes,areprojectedinallregions(highconﬁdence).At1.5°Cglobalwarming,heavyprecipitationandﬂoodingeventsareprojectedtointensifyandbecomemorefrequentinmostregionsinAfrica,Asia(highconﬁdence),NorthAmerica(mediumtohighconﬁdence)andEurope(mediumconﬁdence).At2°Corabove,thesechangesexpandtomoreregionsand/orbecomemoresigniﬁcant(highconﬁdence),andmorefrequentand/orsevereagriculturalandecologicaldroughtsareprojectedinEurope,Africa,AustralasiaandNorth,CentralandSouthAmerica(mediumtohighconﬁdence).Otherprojectedregionalchangesinclude117ParticularlyoverSouthandSouthEastAsia,EastAsiaandWestAfricaapartfromthefarwestSahel.{WGISPMB.3.3}118SeeAnnexI:Glossary.119SeeAnnexI:Glossary.69Section3Witheveryincrementofglobalwarming,regionalchangesinmeanclimateandextremesbecomemorewidespreadandpronouncedthelasttimeglobalsurfacetemperaturewassustainedatorabove2.5°Cwasover3millionyearsago+1.5°C+2°C+3°C+4°C2011-2020wasaround1.1°Cwarmerthan1850-1900TheworldatTheworldatTheworldatTheworldat01Globalwarminglevel(GWL)above1850-1900°Ca)Annualhottest-daytemperaturechangeAnnualhottestdaytemperatureisprojectedtoincreasemosturbanisation(1.5-2timestheGWL)insomemid-latitudeandsemi-aridfurtherintensifieschange(°C)regions,andintheSouthAmericanMonsoonregion.heatextremes01234567b)AnnualmeantotalcolumnsoilmoisturechangeProjectionsofannualmeansoilmoisturelargelyfollowprojectionsinannualmeanprecipitationbutalsoshowchange(σ)somedifferencesduetotheinﬂuenceofevapotranspiration.-1.5-1.0-0.500.51.01.5SectioSnec3tion1smallabsolutechangesmayc)Annualwettest-dayprecipitationchangeAnnualwettestdayprecipitationisprojectedtoincreaseappearlargeasinalmostallcontinentalregions,eveninregionswhere%orσchangeschange(%)projectedannualmeansoilmoisturedeclines.indryregions-40-30-20-10010203040Figure3.1:Projectedchangesofannualmaximumdailytemperature,annualmeantotalcolumnsoilmoistureCMIPandannualmaximumdailyprecipitationatglobalwarminglevelsof1.5°C,2°C,3°C,and4°Crelativeto1850-1900.Simulated(a)annualmaximumtemperaturechange(°C),(b)annualmeantotalcolumnsoilmoisture(standarddeviation),(c)annualmaximumdailyprecipitationchange(%).ChangescorrespondtoCMIP6multi-modelmedianchanges.Inpanels(b)and(c),largepositiverelativechangesindryregionsmaycorrespondtosmallabsolutechanges.Inpanel(b),theunitisthestandarddeviationofinterannualvariabilityinsoilmoistureduring1850-1900.Standarddeviationisawidelyusedmetricincharacterisingdroughtseverity.Aprojectedreductioninmeansoilmoisturebyonestandarddeviationcorrespondstosoilmoistureconditionstypicalofdroughtsthatoccurredaboutonceeverysixyearsduring1850-1900.TheWGIInteractiveAtlas(https://interactive-atlas.ipcc.ch/)canbeusedtoexploreadditionalchangesintheclimatesystemacrosstherangeofglobalwarminglevelspresentedinthisﬁgure.{WGIFigureSPM.5,WGIFigureTS.5,WGIFigure11.11,WGIFigure11.16,WGIFigure11.19}(Cross-SectionBox.2)70Long-TermClimateandDevelopmentFutures3.1.2ImpactsandRelatedRiskschangesinfoodavailabilityanddietqualityareestimatedtoincreaseSection3nutrition-relateddiseasesandthenumberofundernourishedpeople,Foragivenlevelofwarming,manyclimate-relatedrisksareaffectingtens(underlowvulnerabilityandlowwarming)tohundredsofassessedtobehigherthaninAR5(highconﬁdence).Levelsofmillionsofpeople(underhighvulnerabilityandhighwarming),particularlyrisk120forallReasonsforConcern121(RFCs)areassessedtobecomehighamonglow-incomehouseholdsinlow-andmiddle-incomecountriesintoveryhighatlowerglobalwarminglevelscomparedtowhatwassub-SaharanAfrica,SouthAsiaandCentralAmerica(highconﬁdence).assessedinAR5(highconﬁdence).ThisisbaseduponrecentevidenceForexample,snowmeltwateravailabilityforirrigationisprojectedofobservedimpacts,improvedprocessunderstanding,andnewtodeclineinsomesnowmeltdependentriverbasinsbyupto20%knowledgeonexposureandvulnerabilityofhumanandnatural(mediumconﬁdence).Climatechangeriskstocities,settlementssystems,includinglimitstoadaptation.Dependingonthelevelandkeyinfrastructurewillrisesharplyinthemidandlongtermwithofglobalwarming,theassessedlong-termimpactswillbeuptofurtherglobalwarming,especiallyinplacesalreadyexposedtohighmultipletimeshigherthancurrentlyobserved(highconfidence)fortemperatures,alongcoastlines,orwithhighvulnerabilities(high127identiﬁedkeyrisks,e.g.,intermsofthenumberofaffectedpeopleconﬁdence).{WGIISPMB.3.3,WGIISPMB.4.2,WGIISPMB.4.5,WGIITSC.3.3,andspecies.Risks,includingcascadingrisks(see3.1.3)andrisksfromWGIITS.C.12.2}(Figure3.3)overshoot(see3.3.4),areprojectedtobecomeincreasinglyseverewitheveryincrementofglobalwarming(veryhighconfidence).Atglobalwarmingof3°C,additionalrisksinmanysectorsandregions{WGIISPMB.3.3,WGIISPMB.4,WGIISPMB.5,WGII16.6.3;SRCCLSPMA5.3}reachhighorveryhighlevels,implyingwidespreadsystemicimpacts,(Figure3.2,Figure3.3)irreversiblechangeandmanyadditionaladaptationlimits(seeSection3.2)(highconﬁdence).Forexample,veryhighextinctionriskforendemicClimate-relatedrisksfornaturalandhumansystemsarehigherforspeciesinbiodiversityhotspotsisprojectedtoincreaseatleasttenfoldglobalwarmingof1.5°Cthanatpresent(1.1°C)butlowerthanat2°Cifwarmingrisesfrom1.5°Cto3°C(mediumconﬁdence).Projected(highconﬁdence)(seeSection2.1.2).Climate-relatedriskstohealth,increasesindirectﬂooddamagesarehigherby1.4to2timesat2°Clivelihoods,foodsecurity,watersupply,humansecurity,andeconomicand2.5to3.9timesat3°C,comparedto1.5°Cglobalwarmingwithoutgrowthareprojectedtoincreasewithglobalwarmingof1.5°C.Inadaptation(mediumconﬁdence).{WGIISPMB.4.1,WGIISPMB.4.2,terrestrialecosystems,3to14%ofthetensofthousandsofspeciesWGIIFigureSPM.3,WGIITSAppendixAII,WGIIAppendixIGlobaltoassessedwilllikelyfaceaveryhighriskofextinctionataGWLof1.5°C.RegionalAtlasFigureAI.46}(Figure3.2,Figure3.3)Coralreefsareprojectedtodeclinebyafurther70–90%at1.5°Cofglobalwarming(highconﬁdence).AtthisGWL,manylow-elevationGlobalwarmingof4°Candaboveisprojectedtoleadtofar-reachingandsmallglaciersaroundtheworldwouldlosemostoftheirmassorimpactsonnaturalandhumansystems(highconﬁdence).Beyonddisappearwithindecadestocenturies(highconﬁdence).Regionsat4°Cofwarming,projectedimpactsonnaturalsystemsincludelocaldisproportionatelyhigherriskincludeArcticecosystems,drylandregions,extinctionof~50%oftropicalmarinespecies(mediumconﬁdence)smallislanddevelopingstatesandLeastDevelopedCountries(highandbiomeshiftsacross35%ofgloballandarea(mediumconﬁdence).conﬁdence).{WGIISPMB.3,WGIISPMB.4.1,WGIITS.C.4.2;SR1.5SPMA.3,Atthislevelofwarming,approximately10%ofthegloballandareaSR1.5SPMB.4.2,SR1.5SPMB.5,SR1.5SPMB.5.1}(Figure3.3)isprojectedtofacebothincreasinghighanddecreasinglowextremestreamﬂow,affecting,withoutadditionaladaptation,over2.1billionpeopleAt2°Cofglobalwarming,overallrisklevelsassociatedwiththeunequal(mediumconﬁdence)andabout4billionpeopleareprojectedtodistributionofimpacts(RFC3),globalaggregateimpacts(RFC4)andexperiencewaterscarcity(mediumconﬁdence).At4°Cofwarming,thelarge-scalesingularevents(RFC5)wouldbetransitioningtohigh(mediumglobalburnedareaisprojectedtoincreaseby50to70%andtheconﬁdence),thoseassociatedwithextremeweatherevents(RFC2)wouldfirefrequencyby~30%comparedtotoday(mediumconfidence).betransitioningtoveryhigh(mediumconﬁdence),andthoseassociated{WGIISPMB.4.1,WGIISPMB.4.2,WGIITS.C.1.2,WGIITS.C.2.3,withuniqueandthreatenedsystems(RFC1)wouldbeveryhigh(highWGIITS.C.4.1,WGIITS.C.4.4}(Figure3.2,Figure3.3)conﬁdence)(Figure3.3,panela).Withabout2°Cwarming,climate-related120Undetectablerisklevelindicatesnoassociatedimpactsaredetectableandattributabletoclimatechange;moderateriskindicatesassociatedimpactsarebothdetectableandattributabletoclimatechangewithatleastmediumconﬁdence,alsoaccountingfortheotherspeciﬁccriteriaforkeyrisks;highriskindicatessevereandwidespreadimpactsthatarejudgedtobehighononeormorecriteriaforassessingkeyrisks;andveryhighrisklevelindicatesveryhighriskofsevereimpactsandthepresenceofsigniﬁcantirreversibilityorthepersistenceofclimate-relatedhazards,combinedwithlimitedabilitytoadaptduetothenatureofthehazardorimpacts/risks.{WGIIFigureSPM.3}121TheReasonsforConcern(RFC)frameworkcommunicatesscientiﬁcunderstandingaboutaccrualofriskforﬁvebroadcategories(WGIIFigureSPM.3).RFC1:Uniqueandthreatenedsystems:ecologicalandhumansystemsthathaverestrictedgeographicrangesconstrainedbyclimate-relatedconditionsandhavehighendemismorotherdistinctiveproperties.Examplesincludecoralreefs,theArcticanditsIndigenousPeoples,mountainglaciersandbiodiversityhotspots.RFC2:Extremeweatherevents:risks/impactstohumanhealth,livelihoods,assetsandecosystemsfromextremeweathereventssuchasheatwaves,heavyrain,droughtandassociatedwildﬁres,andcoastalﬂooding.RFC3:Distributionofimpacts:risks/impactsthatdisproportionatelyaffectparticulargroupsduetounevendistributionofphysicalclimatechangehazards,exposureorvulnerability.RFC4:Globalaggregateimpacts:impactstosocio-ecologicalsystemsthatcanbeaggregatedgloballyintoasinglemetric,suchasmonetarydamages,livesaffected,specieslostorecosystemdegradationataglobalscale.RFC5:Large-scalesingularevents:relativelylarge,abruptandsometimesirreversiblechangesinsystemscausedbyglobalwarming,suchasicesheetinstabilityorthermohalinecirculationslowing.AssessmentmethodsincludeastructuredexpertelicitationbasedontheliteraturedescribedinWGIISM16.6andareidenticaltoAR5butareenhancedbyastructuredapproachtoimproverobustnessandfacilitatecomparisonbetweenAR5andAR6.ForfurtherexplanationsofglobalrisklevelsandReasonsforConcern,seeWGIITS.AII.{WGIIFigureSPM.3}71SectioSnec3tion1Section3Projectedadverseimpactsandrelatedlossesanddamagesfromclimatechangeescalatewitheveryincrementofglobalwarming(veryhighconﬁdence),buttheywillalsostronglydependonsocio-economicdevelopmenttrajectoriesandadaptationactionstoreducevulnerabilityandexposure(highconﬁdence).Forexample,developmentpathwayswithhigherdemandforfood,animalfeed,andwater,moreresource-intensiveconsumptionandproduction,andlimitedtechnologicalimprovementsresultinhigherrisksfromwaterscarcityindrylands,landdegradationandfoodinsecurity(highconﬁdence).Changesin,forexample,demographyorinvestmentsinhealthsystemshaveeffectonavarietyofhealth-relatedoutcomesincludingheat-relatedmorbidityandmortality(Figure3.3Paneld).{WGIISPMB.3,WGIISPMB.4,WGIIFigureSPM.3;SRCCLSPMA.6}Witheveryincrementofwarming,climatechangeimpactsandriskswillbecomeincreasinglycomplexandmoredifﬁculttomanage.Manyregionsareprojectedtoexperienceanincreaseintheprobabilityofcompoundeventswithhigherglobalwarming,suchasconcurrentheatwavesanddroughts,compoundﬂoodingandﬁreweather.Inaddition,multipleclimaticandnon-climaticriskdriverssuchasbiodiversitylossorviolentconﬂictwillinteract,resultingincompoundingoverallriskandriskscascadingacrosssectorsandregions.Furthermore,riskscanarisefromsomeresponsesthatareintendedtoreducetherisksofclimatechange,e.g.,adversesideeffectsofsomeemissionreductionandcarbondioxideremoval(CDR)measures(see3.4.1).(highconfidence){WGISPMC.2.7,WGIFigureSPM.6,WGITS.4.3;WGIISPMB.1.7,WGIIB.2.2,WGIISPMB.5,WGIISPMB.5.4,WGIISPMC.4.2,WGIISPMB.5,WGIICCB2}SolarRadiationModiﬁcation(SRM)approaches,iftheyweretobeimplemented,introduceawidespreadrangeofnewriskstopeopleandecosystems,whicharenotwellunderstood.SRMhasthepotentialtooffsetwarmingwithinoneortwodecadesandamelioratesomeclimatehazardsbutwouldnotrestoreclimatetoapreviousstate,andsubstantialresidualorovercompensatingclimatechangewouldoccuratregionalandseasonalscales(highconﬁdence).EffectsofSRMwoulddependonthespeciﬁcapproachused122,andasuddenandsustainedterminationofSRMinahighCO2emissionsscenariowouldcauserapidclimatechange(highconﬁdence).SRMwouldnotstopatmosphericCO2concentrationsfromincreasingnorreduceresultingoceanacidiﬁcationundercontinuedanthropogenicemissions(highconﬁdence).LargeuncertaintiesandknowledgegapsareassociatedwiththepotentialofSRMapproachestoreduceclimatechangerisks.LackofrobustandformalSRMgovernanceposesrisksasdeploymentbyalimitednumberofstatescouldcreateinternationaltensions.{WGI4.6;WGIISPMB.5.5;WGIII14.4.5.1;WGIII14Cross-WorkingGroupBoxSolarRadiationModification;SR1.5SPMC.1.4}122SeveralSRMapproacheshavebeenproposed,includingstratosphericaerosolinjection,marinecloudbrightening,ground-basedalbedomodiﬁcations,andoceanalbedochange.SeeAnnexI:Glossary.72Long-TermClimateandDevelopmentFuturesFutureclimatechangeisprojectedtoincreasetheseverityofimpactsacrossnaturalandhumansystemsandwillincreaseregionaldifferencesExamplesofimpactswithoutadditionaladaptationa)Riskof0%0.1151020406080100%specieslossesPercentageofanimal1Projectedtemperatureconditionsabovespeciesandseagrassestheestimatedhistorical(1850-2005)exposedtopotentiallymaximummeanannualtemperaturedangeroustemperatureexperiencedbyeachspecies,assumingconditions1,2nospeciesrelocation.1.5°C2.0°C2Includes30,652speciesofbirds,mammals,reptiles,amphibians,marineﬁsh,benthicmarineinvertebrates,krill,cephalopods,corals,andseagrasses.3.0°C4.0°Cb)Heat-humidity0days11050100150200250300365daysriskstohumanhealthHistorical1991–20051.7–2.3°C2.4–3.1°C4.2–5.4°CDaysperyearwhere3Projectedregionalimpactsutilizeaglobalthresholdbeyondwhichdailymeansurfaceairtemperatureandrelativehumiditymayinducecombinedtemperatureandhyperthermiathatposesariskofmortality.Thedurationandintensityofheatwavesarenotpresentedhere.Heat-relatedhealthoutcomeshumidityconditionsposeariskvarybylocationandarehighlymoderatedbysocio-economic,occupationalandothernon-climaticdeterminantsofindividualhealthandofmortalitytoindividuals3socio-economicvulnerability.Thethresholdusedinthesemapsisbasedonasinglestudythatsynthesizeddatafrom783casestoSection3determinetherelationshipbetweenheat-humidityconditionsandmortalitydrawnlargelyfromobservationsintemperateclimates.c)Foodproduction-35%-30-25-20-15-10-3+3+10+15+20+25+30+35%impactsc1)Maizeyield41.6–2.4°C3.3–4.8°C3.9–6.0°CChanges(%)inyield4Projectedregionalimpactsreﬂectbiophysicalresponsestochangingtemperature,precipitation,solarradiation,humidity,wind,andCO2enhancementofgrowthandwaterretentionincurrentlycultivatedareas.Modelsassumethatirrigatedareasarenotwater-limited.Modelsdonotrepresentpests,diseases,futureagro-technologicalchangesandsomeextremeclimateresponses.c2)Fisheriesyield5Areaswithlittleornoproduction,ornotassessedChanges(%)inmaximumcatchAreaswithmodeldisagreementpotential0.9–2.0°C3.4–5.2°C5Projectedregionalimpactsreﬂectﬁsheriesandmarineecosystemresponsestooceanphysicalandbiogeochemicalconditionssuchastemperature,oxygenlevelandnetprimaryproduction.Modelsdonotrepresentchangesinﬁshingactivitiesandsomeextremeclimaticconditions.ProjectedchangesintheArcticregionshavelowconﬁdenceduetouncertaintiesassociatedwithmodellingmultipleinteractingdriversandecosystemresponses.73SectioSnec3tion1Section3Figure3.2:Projectedrisksandimpactsofclimatechangeonnaturalandhumansystemsatdifferentglobalwarminglevels(GWLs)relativeto1850-1900levels.ProjectedrisksandimpactsshownonthemapsarebasedonoutputsfromdifferentsubsetsofEarthsystemmodelsthatwereusedtoprojecteachimpactindicatorwithoutadditionaladaptation.WGIIprovidesfurtherassessmentoftheimpactsonhumanandnaturalsystemsusingtheseprojectionsandadditionallinesofevidence.(a)Risksofspecieslossesasindicatedbythepercentageofassessedspeciesexposedtopotentiallydangeroustemperatureconditions,asdeﬁnedbyconditionsbeyondtheestimatedhistorical(1850–2005)maximummeanannualtemperatureexperiencedbyeachspecies,atGWLsof1.5°C,2°C,3°Cand4°C.Underpinningprojectionsoftemperaturearefrom21EarthsystemmodelsanddonotconsiderextremeeventsimpactingecosystemssuchastheArctic.(b)Risktohumanhealthasindicatedbythedaysperyearofpopulationexposuretohypothermicconditionsthatposeariskofmortalityfromsurfaceairtemperatureandhumidityconditionsforhistoricalperiod(1991–2005)andatGWLsof1.7°Cto2.3°C(mean=1.9°C;13climatemodels),2.4°Cto3.1°C(2.7°C;16climatemodels)and4.2°Cto5.4°C(4.7°C;15climatemodels).InterquartilerangesofWGLsby2081–2100underRCP2.6,RCP4.5andRCP8.5.ThepresentedindexisconsistentwithcommonfeaturesfoundinmanyindicesincludedwithinWGIandWGIIassessments.(c)Impactsonfoodproduction:(c1)ChangesinmaizeyieldatprojectedGWLsof1.6°Cto2.4°C(2.0°C),3.3°Cto4.8°C(4.1°C)and3.9°Cto6.0°C(4.9°C).Medianyieldchangesfromanensembleof12cropmodels,eachdrivenbybias-adjustedoutputsfrom5EarthsystemmodelsfromtheAgriculturalModelIntercomparisonandImprovementProject(AgMIP)andtheInter-SectoralImpactModelIntercomparisonProject(ISIMIP).Mapsdepict2080–2099comparedto1986–2005forcurrentgrowingregions(>10ha),withthecorrespondingrangeoffutureglobalwarminglevelsshownunderSSP1-2.6,SSP3-7.0andSSP5-8.5,respectively.Hatchingindicatesareaswhere<70%oftheclimate-cropmodelcombinationsagreeonthesignofimpact.(c2)Changesinmaximumﬁsheriescatchpotentialby2081–2099relativeto1986-2005atprojectedGWLsof0.9°Cto2.0°C(1.5°C)and3.4°Cto5.2°C(4.3°C).GWLsby2081–2100underRCP2.6andRCP8.5.Hatchingindicateswherethetwoclimate-ﬁsheriesmodelsdisagreeinthedirectionofchange.Largerelativechangesinlowyieldingregionsmaycorrespondtosmallabsolutechanges.BiodiversityandﬁsheriesinAntarcticawerenotanalysedduetodatalimitations.Foodsecurityisalsoaffectedbycropandﬁsheryfailuresnotpresentedhere.{WGIIFig.TS.5,WGIIFigTS.9,WGIIAnnexI:GlobaltoRegionalAtlasFigureAI.15,FigureAI.22,FigureAI.23,FigureAI.29;WGII7.3.1.2,7.2.4.1,SROCCFigureSPM.3}(3.1.2,Cross-SectionBox.2)74Long-TermClimateandDevelopmentFuturesRisksareincreasingwitheveryincrementofwarminga)HighrisksarenowassessedtooccuratlowerglobalwarminglevelsriskisthepotentialforadverseconsequencesGlobalsurfacetemperaturechangeGlobalReasonsforConcern(RFCs)relativeto1850–1900inAR5(2014)vs.AR6(2022)Risk/impact°C5Veryhigh°C5veryhighHighhigh4ModerateshadingrepresentstheUndetectable4uncertaintyrangesforthelowandhighTransitionrangeemissionsscenarios••Conﬁdencelevelintermediate3•assignedtotransitionrange3••2low2••••••••••••••••••••10verylow1.5•••••••••••–12011-2020was1•••1950around1.1°Cwarmer0AR5AR6than1850-1900AR5AR6AR5AR6AR5AR6AR5AR6•ExtremeDistributionGlobalLargescale••weatherofimpactsaggregate•••eventsimpactssingular••••eventsUnique&LowVeryhighthreatened2000201520502100midpointoftransitionsystemsb)RisksdifferbysystemLand-basedsystemsOcean/coastalecosystems°C5e.g.over100million•••additionalpeople4••••exposed••e.g.coral•••••reefsdecline3>99%••••e.g.coral••••reefsdeclineby70–90%•••••2•••••••••••••••••••••••e.g.increaseinthe1.5••lengthofﬁreseason1••••••••••••••••••••••••••••••••••••••0WildﬁrePermafrostBiodiversityDrylandTreeCarbonWarm-waterKelpSeagrassEpipelagicRockySaltdamagedegradationlosswatermortalitylosscoralsforestsmeadowsshoresmarshesscarcitySection3c)RiskstocoastalgeographiesincreasewithsealevelriseanddependonresponsesGlobalmeansealevelriserelativeto1900rRrRrRrRcmcmRisksareassessedwith100veryhigh100mediumconﬁdencelow-likelihood,highimpacthighrstoryline,includingice-sheetNo-to-moderate75instabilityprocessesintermediate75responseRlowMaximumpotentialresponse50verylow50252000205025UrbanArcticLargetropicalResource-rich1986-2005atollislandscommunitiesagriculturalcoastalcities01950baseline0deltas2100d)AdaptationandHeat-relatedmorbidityandmortalityFoodinsecurityTheSSP1pathwayillustratessocio-economicpathways°C4(availability,access)aworldwithlowpopulationaffectlevelsofclimategrowth,highincome,andrelatedrisks3SSP3SSP1reducedinequalities,foodproducedinlowGHGLimitedadaptation(failuretoproactively••••emissionsystems,effectiveadapt;lowinvestmentinhealthsystems);landuseregulationandhighincompleteadaptation(incomplete2••••••••••••••••••••••••adaptivecapacity(i.e.,lowadaptationplanning;moderateinvestment1.5challengestoadaptation).inhealthsystems);proactiveadaptationTheSSP3pathwayhasthe(proactiveadaptationmanagement;higher1oppositetrends.investmentinhealthsystems)••0highlowLimitedIncompleteProactiveChallengestoAdaptationadaptationadaptationadaptation75Section3e)ExamplesofkeyrisksindifferentregionsAbsenceofriskdiagramsdoesnotimplyabsenceofriskswithinaregion.ThedevelopmentofsyntheticdiagramsforSmallIslands,AsiaandCentralandSouthAmericawaslimitedduetothepaucityofadequatelydownscaledclimateprojections,withuncertaintyinthedirectionofchange,thediversityofclimatologiesandsocioeconomiccontextsacrosscountrieswithinaregion,andtheresultingfewnumbersofimpactandriskprojectionsfordifferentwarminglevels.Theriskslistedareofatleastmediumconﬁdencelevel:Small-Lossofterrestrial,marineandcoastalbiodiversityandecosystemservices°C4Islands-Lossoflivesandassets,risktofoodsecurityandeconomicdisruptionduetodestructionofsettlementsandinfrastructure3-Economicdeclineandlivelihoodfailureofﬁsheries,agriculture,tourismandfrom•••biodiversitylossfromtraditionalagroecosystems-Reducedhabitabilityofreefandnon-reefislandsleadingtoincreaseddisplacement2••••••••••••••••••••••••••••-Risktowatersecurityinalmosteverysmallisland1.51North-Climate-sensitivementalhealthoutcomes,humanmortalityandmorbiditydueto0BiodiversityMortalityandDelayedAmericaincreasingaveragetemperature,weatherandclimateextremes,andcompoundFoodandmorbidityimpactsofclimatehazardssealevel-Riskofdegradationofmarine,coastalandterrestrialecosystems,includinglossofproductionecosystemsfromheatandriseinthebiodiversity,function,andprotectiveservicesfromcrops,inAfricainfectiousMediterranean-Risktofreshwaterresourceswithconsequencesforecosystems,reducedsurfacewaterﬁsheriesanddiseaseavailabilityforirrigatedagriculture,otherhumanuses,anddegradedwaterqualitylivestockinAfrica-Risktofoodandnutritionalsecuritythroughchangesinagriculture,livestock,hunting,ﬁsheries,andaquacultureproductivityandaccessinAfrica-Riskstowell-being,livelihoodsandeconomicactivitiesfromcascadingand°C4compoundingclimatehazards,includingriskstocoastalcities,settlementsandinfrastructurefromsealevelrise3•••••••Europe-Riskstopeople,economiesandinfrastructuresduetocoastalandinlandﬂooding2•••••••••••••••••••••••••••••••-Stressandmortalitytopeopleduetoincreasingtemperaturesandheatextremes1.5-Marineandterrestrialecosystemsdisruptions-Waterscarcitytomultipleinterconnectedsectors1-Lossesincropproduction,duetocompoundheatanddryconditions,andextremeweather0WaterqualityHealthandWaterscarcityCoastalHeatstress,andwellbeingtopeopleinﬂoodingtomortalityavailabilityinthesoutheasternpeopleandintheMediterraneanEuropeandmorbidityCentral-RisktowatersecurityMediterraneaninfrastructurestopeopleand-Severehealtheffectsduetoincreasingepidemics,inparticularvector-bornediseasesinEuropeinEurope-CoralreefecosystemsdegradationduetocoralbleachingSectioSnec3tion1South-Risktofoodsecurityduetofrequent/extremedroughts°C4America-Damagestolifeandinfrastructureduetoﬂoods,landslides,sealevelrise,stormsurgesandcoastalerosion3••Aus--Degradationoftropicalshallowcoralreefsandassociatedbiodiversityand2••••••••••••••••••••tralasiaecosystemservicevalues1.5-Lossofhumanandnaturalsystemsinlow-lyingcoastalareasduetosealevelrise-Impactonlivelihoodsandincomesduetodeclineinagriculturalproduction1••••••••••••••••-Increaseinheat-relatedmortalityandmorbidityforpeopleandwildlife-LossofalpinebiodiversityinAustraliaduetolesssnow0ReducedCostsandLymeLossandCascadingviabilityofAsia-Urbaninfrastructuredamageandimpactsonhumanwell-beingandhealthduetotourism-damagesdiseaseinﬂooding,especiallyincoastalcitiesandsettlementsdegradationofimpactsonrelatedtoNorth-BiodiversitylossandhabitatshiftsaswellasassociateddisruptionsindependentcoralreefsincitiesandrelatedmaintenanceandAmericahumansystemsacrossfreshwater,land,andoceanecosystemsactivitiesinreconstructionofunder-Morefrequent,extensivecoralbleachingandsubsequentcoralmortalityinducedbyAustraliasettlementstransportationincompleteoceanwarmingandacidiﬁcation,sealevelrise,marineheatwavesandresourceinAustralasiaNorthextractionAmerica-Declineincoastalﬁsheryresourcesduetosealevelrise,decreaseinprecipitationininfrastructureinadaptationsomepartsandincreaseintemperatureNorthAmericascenario-Risktofoodandwatersecurityduetoincreasedtemperatureextremes,rainfallvariabilityanddrought°C4••••••3•••••••••Africa-Speciesextinctionandreductionorirreversiblelossofecosystemsandtheirservices,2•••••••••••••••includingfreshwater,landandoceanecosystems1.5-Risktofoodsecurity,riskofmalnutrition(micronutrientdeﬁciency),andlossof••livelihoodduetoreducedfoodproductionfromcrops,livestockandﬁsheries1-Riskstomarineecosystemhealthandtolivelihoodsincoastalcommunities-Increasedhumanmortalityandmorbidityduetoincreasedheatandinfectiousdiseases0Sea-iceChangesinCostsSea-iceChanges(includingvector-borneanddiarrhoealdiseases)andlossesdependentinkrill-Reducedeconomicoutputandgrowth,andincreasedinequalityandpovertyratesecosystemsﬁsheriescatchecosystemsﬁsheries-Increasedrisktowaterandenergysecurityduetodroughtandheatfromsea-iceforPollockforkeyinthechangeinandinfrastructureinthetheArcticPaciﬁcCodintheArcticAntarcticAntarcticintheArctic76Long-TermClimateandDevelopmentFuturesFigure3.3:Syntheticriskdiagramsofglobalandsectoralassessmentsandexamplesofregionalkeyrisks.Theburningembersresultfromaliteraturebasedexpertelicitation.Panel(a):Left-Globalsurfacetemperaturechangesin°Crelativeto1850–1900.ThesechangeswereobtainedbycombiningCMIP6modelsimulationswithobservationalconstraintsbasedonpastsimulatedwarming,aswellasanupdatedassessmentofequilibriumclimatesensitivity.VerylikelyrangesareshownforthelowandhighGHGemissionsscenarios(SSP1-2.6andSSP3-7.0).Right-GlobalReasonsforConcern,comparingAR6(thickembers)andAR5(thinembers)assessments.DiagramsareshownforeachRFC,assuminglowtonoadaptation(i.e.,adaptationisfragmented,localisedandcomprisesincrementaladjustmentstoexistingpractices).However,thetransitiontoaveryhigh-risklevelhasanemphasisonirreversibilityandadaptationlimits.Thehorizontallinedenotesthepresentglobalwarmingof1.1°Cwhichisusedtoseparatetheobserved,pastimpactsbelowthelinefromthefutureprojectedrisksaboveit.LinesconnectthemidpointsofthetransitionfrommoderatetohighriskacrossAR5andAR6.Panel(b):Risksforland-basedsystemsandocean/coastalecosystems.Diagramsshownforeachriskassumelowtonoadaptation.Textbubblesindicateexamplesofimpactsatagivenwarminglevel.Panel(c):Left-Globalmeansealevelchangeincentimetres,relativeto1900.Thehistoricalchanges(black)areobservedbytidegaugesbefore1992andaltimetersafterwards.Thefuturechangesto2100(colouredlinesandshading)areassessedconsistentlywithobservationalconstraintsbasedonemulationofCMIP,ice-sheet,andglaciermodels,andlikelyrangesareshownforSSP1-2.6andSSP3-7.0.Right-Assessmentofthecombinedriskofcoastalﬂooding,erosionandsalinizationforfourillustrativecoastalgeographiesin2100,duetochangingmeanandextremesealevels,undertworesponsescenarios,withrespecttotheSROCCbaselineperiod(1986–2005)andindicatingtheIPCCAR6baselineperiod(1995–2014).Theassessmentdoesnotaccountforchangesinextremesealevelbeyondthosedirectlyinducedbymeansealevelrise;risklevelscouldincreaseifotherchangesinextremesealevelswereconsidered(e.g.,duetochangesincycloneintensity).“No-to-moderateresponse”describeseffortsasoftoday(i.e.,nofurthersigniﬁcantactionornewtypesofactions).“Maximumpotentialresponse”representsacombinationofresponsesimplementedtotheirfullextentandthussigniﬁcantadditionaleffortscomparedtotoday,assumingminimalﬁnancial,socialandpoliticalbarriers.Theassessmentcriteriaincludeexposureandvulnerability(densityofassets,levelofdegradationofterrestrialandmarinebufferecosystems),coastalhazards(ﬂooding,shorelineerosion,salinization),in-situresponses(hardengineeredcoastaldefences,ecosystemrestorationorcreationofnewnaturalbuffersareas,andsubsidencemanagement)andplannedrelocation.Plannedrelocationreferstomanagedretreatorresettlement.Forceddisplacementisnotconsideredinthisassessment.Thetermresponseisusedhereinsteadofadaptationbecausesomeresponses,suchasretreat,mayormaynotbeconsideredtobeadaptation.Panel(d):Left-Heat-sensitivehumanhealthoutcomesunderthreescenariosofadaptationeffectiveness.ThediagramsaretruncatedatthenearestwholeºCwithintherangeoftemperaturechangein2100underthreeSSPscenarios.Right-Risksassociatedwithfoodsecurityduetoclimatechangeandpatternsofsocio-economicdevelopment.Riskstofoodsecurityincludeavailabilityandaccesstofood,includingpopulationatriskofhunger,foodpriceincreasesandincreasesindisabilityadjustedlifeyearsattributabletochildhoodunderweight.Risksareassessedfortwocontrastedsocio-economicpathways(SSP1andSSP3)excludingtheeffectsoftargetedmitigationandadaptationpolicies.Panel(e):Examplesofregionalkeyrisks.Risksidentiﬁedareofatleastmediumconﬁdencelevel.Keyrisksareidentiﬁedbasedonthemagnitudeofadverseconsequences(pervasivenessoftheconsequences,degreeofchange,irreversibilityofconsequences,potentialforimpactthresholdsortippingpoints,potentialforcascadingeffectsbeyondsystemboundaries);likelihoodofadverseconsequences;temporalcharacteristicsoftherisk;andabilitytorespondtotherisk,e.g.,byadaptation.{WGIFigureSPM.8;WGIISPMB.3.3,WGIIFigureSPM.3,WGIISM16.6,WGIISM16.7.4;SROCCFigureSPM.3d,SROCCSPM.5a,SROCC4SM;SRCCLFigureSPM.2,SRCCL7.3.1,SRCCL7SM}(Cross-SectionBox.2)3.1.3TheLikelihoodandRisksofAbruptandIrreversibleandrisksforcoastalecosystems,peopleandinfrastructurewillcontinueSection3Changetoincreasebeyond2100(highconﬁdence).Atsustainedwarminglevelsbetween2°Cand3°C,theGreenlandandWestAntarcticiceThelikelihoodofabruptandirreversiblechangesandtheirimpactssheetswillbelostalmostcompletelyandirreversiblyovermultipleincreasewithhigherglobalwarminglevels(highconﬁdence).millennia(limitedevidence).TheprobabilityandrateoficemasslossAswarminglevelsincrease,sodotherisksofspeciesextinctionorincreasewithhigherglobalsurfacetemperatures(highconﬁdence).irreversiblelossofbiodiversityinecosystemssuchasforests(mediumOverthenext2000years,globalmeansealevelwillrisebyaboutconﬁdence),coralreefs(veryhighconﬁdence)andinArcticregions2to3mifwarmingislimitedto1.5°Cand2to6miflimitedto2°C(highconﬁdence).Risksassociatedwithlarge-scalesingularevents(lowconﬁdence).Projectionsofmulti-millennialglobalmeansealevelortippingpoints,suchasicesheetinstabilityorecosystemlossfromriseareconsistentwithreconstructedlevelsduringpastwarmclimatetropicalforests,transitiontohighriskbetween1.5°Cto2.5°C(mediumperiods:globalmeansealevelwasverylikely5to25mhigherthantodayconﬁdence)andtoveryhighriskbetween2.5°Cto4°C(lowconﬁdence).roughly3millionyearsago,whenglobaltemperatureswere2.5°CtoTheresponseofbiogeochemicalcyclestoanthropogenicperturbations4°Chigherthan1850–1900(mediumconﬁdence).Furtherexamplescanbeabruptatregionalscalesandirreversibleondecadaltocenturyofunavoidablechangesintheclimatesystemduetomulti-decadaltimescales(highconﬁdence).Theprobabilityofcrossinguncertainorlongerresponsetimescalesincludecontinuedglaciermelt(veryhighregionalthresholdsincreaseswithfurtherwarming(highconﬁdence).conﬁdence)andpermafrostcarbonloss(highconﬁdence).{WGISPMB.5.2,{WGISPMC.3.2,WGIBoxTS.9,WGITS.2.6;WGIIFigureSPM.3,WGISPMB.5.3,WGISPMB.5.4,WGISPMC.2.5,WGIBoxTS.4,WGIISPMB.3.1,WGIISPMB.4.1,WGIISPMB.5.2,WGIITableTS.1,WGIBoxTS.9,WGI9.5.1;WGIITSC.5;SROCCSPMB.3,SROCCSPMB.6,WGIITS.C.1,WGIITS.C.13.3;SROCCSPMB.4}SROCCSPMB.9}(Figure3.4)SealevelriseisunavoidableforcenturiestomillenniadueTheprobabilityoflow-likelihoodoutcomesassociatedwithtocontinuingdeepoceanwarmingandicesheetmelt,andpotentiallyverylargeimpactsincreaseswithhigherglobalsealevelswillremainelevatedforthousandsofyears(highwarminglevels(highconﬁdence).Warmingsubstantiallyabovetheconﬁdence).Globalmeansealevelrisewillcontinueinthe21stassessedverylikelyrangeforagivenscenariocannotberuledout,andcentury(virtuallycertain),withprojectedregionalrelativesealevelrisethereishighconﬁdencethiswouldleadtoregionalchangesgreaterwithin20%oftheglobalmeanalongtwo-thirdsoftheglobalcoastlinethanassessedinmanyaspectsoftheclimatesystem.Low-likelihood,(mediumconﬁdence).Themagnitude,therate,thetimingofthresholdhigh-impactoutcomescouldoccuratregionalscalesevenforglobalwarmingexceedances,andthelong-termcommitmentofsealevelrisedependwithintheverylikelyassessedrangeforagivenGHGemissionsscenario.onemissions,withhigheremissionsleadingtogreaterandfasterratesGlobalmeansealevelriseabovethelikelyrange–approaching2mbyofsealevelrise.Duetorelativesealevelrise,extremesealevelevents2100andinexcessof15mby2300underaveryhighGHGemissionsthatoccurredoncepercenturyintherecentpastareprojectedtooccurscenario(SSP5-8.5)(lowconfidence)–cannotberuledoutduetoatleastannuallyatmorethanhalfofalltidegaugelocationsby2100deepuncertaintyinice-sheetprocesses123andwouldhavesevere123Thisoutcomeischaracterisedbydeepuncertainty:Itslikelihooddefiesquantitativeassessmentbutisconsideredduetoitshighpotentialimpact.{WGIBoxTS.1;WGIICross-ChapterBoxDEEP}77Section3impactsonpopulationsinlowelevationcoastalzones.Ifglobalsuchasasouthwardshiftinthetropicalrainbelt,andlargeimpactswarmingincreases,somecompoundextremeevents124willonecosystemsandhumanactivities.Asequenceoflargeexplosivebecomemorefrequent,withhigherlikelihoodofunprecedentedvolcaniceruptionswithindecades,ashaveoccurredinthepast,isaintensities,durationsorspatialextent(highconfidence).Thelow-likelihoodhigh-impacteventthatwouldleadtosubstantialcoolingAtlanticMeridionalOverturningCirculationisverylikelytoweakengloballyandregionalclimateperturbationsoverseveraldecades.overthe21stcenturyforallconsideredscenarios(highconﬁdence),{WGISPMB.5.3,WGISPMC.3,WGISPMC.3.1,WGISPMC.3.2,howeveranabruptcollapseisnotexpectedbefore2100(mediumWGISPMC.3.3,WGISPMC.3.4,WGISPMC.3.5,WGIFigureSPM.8,conﬁdence).Ifsuchalowprobabilityeventweretooccur,itwouldveryWGIBoxTS.3,WGIFigureTS.6,WGIBox9.4;WGIISPMB.4.5,WGIISPMC.2.8;likelycauseabruptshiftsinregionalweatherpatternsandwatercycle,SROCCSPMB.2.7}(Figure3.4,Cross-SectionBox.2)124SeeAnnexI:Glossary.Examplesofcompoundextremeeventsareconcurrentheatwavesanddroughtsorcompoundﬂooding.{WGISPMFootnote18}3.2Long-termAdaptationOptionsandLimitsWithincreasingwarming,adaptationoptionswillbecomemoreconstrainedandlesseffective.Athigherlevelsofwarming,lossesanddamageswillincrease,andadditionalhumanandnaturalsystemswillreachadaptationlimits.Integrated,cross-cuttingmulti-sectoralsolutionsincreasetheeffectivenessofadaptation.Maladaptationcancreatelock-insofvulnerability,exposureandrisksbutcanbeavoidedbylong-termplanningandtheimplementationofadaptationactionsthatareﬂexible,multi-sectoralandinclusive.(highconﬁdence)SectioSnec3tion1Theeffectivenessofadaptationtoreduceclimateriskisdocumented(mediumconfidence).By2°C,softlimitsareprojectedformultipleforspeciﬁccontexts,sectorsandregionsandwilldecreasewithstaplecrops,particularlyintropicalregions(highconﬁdence).By3°C,increasingwarming(highconﬁdence)125.Forexample,commonsoftlimitsareprojectedforsomewatermanagementmeasuresforadaptationresponsesinagriculture–adoptingimprovedcultivarsandmanyregions,withhardlimitsprojectedforpartsofEurope(mediumagronomicpractices,andchangesincroppingpatternsandcropconﬁdence).{WGIISPMC.3,WGIISPMC.3.3,WGIISPMC.3.4,WGIISPMC.3.5,systems–willbecomelesseffectivefrom2°CtohigherlevelsofWGIITS.D.2.2,WGIITS.D.2.3;SR1.5SPMB.6;SROCCSPMC.1}warming(highconfidence).Theeffectivenessofmostwater-relatedadaptationoptionstoreduceprojectedrisksdeclineswithincreasingIntegrated,cross-cuttingmulti-sectoralsolutionsincreasethewarming(highconfidence).Adaptationsforhydropowerandeffectivenessofadaptation.Forexample,inclusive,integratedthermo-electricpowergenerationareeffectiveinmostregionsuptoandlong-termplanningatlocal,municipal,sub-nationalandnational1.5°Cto2°C,withdecreasingeffectivenessathigherlevelsofwarmingscales,togetherwitheffectiveregulationandmonitoringsystems(mediumconﬁdence).Ecosystem-basedAdaptationisvulnerabletoandﬁnancialandtechnologicalresourcesandcapabilitiesfosterclimatechangeimpacts,witheffectivenessdecliningwithincreasingurbanandruralsystemtransition.Therearearangeofcross-cuttingglobalwarming(highconﬁdence).Globally,adaptationoptionsrelatedadaptationoptions,suchasdisasterriskmanagement,earlywarningtoagroforestryandforestryhaveasharpdeclineineffectivenessat3°C,systems,climateservicesandriskspreadingandsharingthathavewithasubstantialincreaseinresidualrisk(mediumconﬁdence).broadapplicabilityacrosssectorsandprovidegreaterbeneﬁtstoother{WGIISPMC.2,WGIISPMC.2.1,WGIISPMC.2.5,WGIISPMC.2.10,adaptationoptionswhencombined.TransitioningfromincrementaltoWGIIFigureTS.6Panel(e),4.7.2}transformationaladaptation,andaddressingarangeofconstraints,primarilyintheﬁnancial,governance,institutionalandpolicydomains,Withincreasingglobalwarming,morelimitstoadaptationwillbecanhelpovercomesoftadaptationlimits.However,adaptationdoesreachedandlossesanddamages,stronglyconcentratedamongthenotpreventalllossesanddamages,evenwitheffectiveadaptationandpoorestvulnerablepopulations,willincrease(highconﬁdence).beforereachingsoftandhardlimits.(highconﬁdence){WGIISPMC.2,Alreadybelow1.5°C,autonomousandevolutionaryadaptationWGIISPMC.2.6,WGIISPM.C.2.13,WGIISPMC.3.1,WGIISPM.C.3.4,responsesbyterrestrialandaquaticecosystemswillincreasinglyWGIISPMC.3.5,WGIIFigureTS.6Panel(e)}facehardlimits(highconﬁdence)(Section2.1.2).Above1.5°C,someecosystem-basedadaptationmeasureswilllosetheireffectivenessMaladaptiveresponsestoclimatechangecancreatelock-insofinprovidingbeneﬁtstopeopleastheseecosystemswillreachhardvulnerability,exposureandrisksthataredifﬁcultandexpensiveadaptationlimits(highconﬁdence).Adaptationtoaddresstherisksoftochangeandexacerbateexistinginequalities.Actionsthatfocusheatstress,heatmortalityandreducedcapacitiesforoutdoorworkonsectorsandrisksinisolationandonshort-termgainsoftenleadforhumansfacesoftandhardlimitsacrossregionsthatbecometomaladaptation.Adaptationoptionscanbecomemaladaptiveduesigniﬁcantlymoresevereat1.5°C,andareparticularlyrelevantfortotheirenvironmentalimpactsthatconstrainecosystemservicesandregionswithwarmclimates(highconﬁdence).Above1.5°Cglobaldecreasebiodiversityandecosystemresiliencetoclimatechangeorbywarminglevel,limitedfreshwaterresourcesposepotentialhardlimitscausingadverseoutcomesfordifferentgroups,exacerbatinginequity.forsmallislandsandforregionsdependentonglacierandsnowmeltMaladaptationcanbeavoidedbyﬂexible,multi-sectoral,inclusiveand124SeeAnnexI:Glossary.Examplesofcompoundextremeeventsareconcurrentheatwavesanddroughtsorcompoundﬂooding.{WGISPMFootnote18}125Therearelimitationstoassessingthefullscopeofadaptationoptionsavailableinthefuturesincenotallpossiblefutureadaptationresponsescanbeincorporatedinclimateimpactmodels,andprojectionsoffutureadaptationdependoncurrentlyavailabletechnologiesorapproaches.{WGII4.7.2}78Long-TermClimateandDevelopmentFutureslong-termplanningandimplementationofadaptationactionswithbeneﬁtstomanysectorsandsystems.(highconﬁdence){WGIISPMC.4,WGIISPM.C.4.1,WGIISPMC.4.2,WGIISPMC.4.3}Sealevelriseposesadistinctiveandsevereadaptationchallengeasitimpliesbothdealingwithslowonsetchangesandincreasesinthefrequencyandmagnitudeofextremesealevelevents(highconﬁdence).Suchadaptationchallengeswouldoccurmuchearlierunderhighratesofsealevelrise(highconﬁdence).Responsestoongoingsealevelriseandlandsubsidenceincludeprotection,accommodation,advanceandplannedrelocation(highconﬁdence).Theseresponsesaremoreeffectiveifcombinedand/orsequenced,plannedwellahead,alignedwithsocioculturalvaluesandunderpinnedbyinclusivecommunityengagementprocesses(highconﬁdence).Ecosystem-basedsolutionssuchaswetlandsprovideco-beneﬁtsfortheenvironmentandclimatemitigation,andreducecostsforﬂooddefences(mediumconﬁdence),buthavesite-speciﬁcphysicallimits,atleastabove1.5ºCofglobalwarming(highconﬁdence)andloseeffectivenessathighratesofsealevelrisebeyond0.5to1cmyr-1(mediumconﬁdence).Seawallscanbemaladaptiveastheyeffectivelyreduceimpactsintheshorttermbutcanalsoresultinlock-insandincreaseexposuretoclimaterisksinthelongtermunlesstheyareintegratedintoalong-termadaptiveplan(highconﬁdence).{WGISPMC.2.5;WGIISPMC.2.8,WGIISPMC.4.1;WGII13.10,WGIICross-ChapterBoxSLR;SROCCSPMB.9,SROCCSPMC.3.2,SROCCFigureSPM.4,SROCCFigureSPM.5c}(Figure3.4)Section379Section3Sealevelrise15mgreaterthan15mcannotberuledoutwithverySealevelrisewillcontinueformillennia,buthowhighemissions7mfastandhowmuchdependsonfutureemissionsa)Sealevelrise:observationsandprojections2020-2100,2150,2300(relativeto1900)6mUnavoidablesealevelrisewillcause:thiscanbechronichighveryhighemissionsscenariorangetidefloodingandextreme5mfloodingduringstorms5m4mLossesofcoastalGroundwaterFloodinganddamages4mecosystemsandsalinisationtocoastalinfrastructureecosystemservicesThesecascadeintorisksto:livelihoods,settlements,health,well-being,foodandwatersecurityandculturalvalues.3m3mlikelylowemissionsscenariorangerangessealevelofseaBy2050:riseby2100levelriseGlobalsealevelrise2mExtremesealeveleventsthatdependson2minmetersrelativeto19001billionoccuredoncepercenturywillbe1mtheemissionspeopleexposed20-30timesmorefrequentscenario01900veryhighhigh1mintermediatelowSectioSnec3tion1verylowObserved01950200020202050210021502300Low-likelihood,high-impactstoryline,includingicesheetinstabilityprocessesundertheveryhighemissionsscenarioRespondingtosealevelriserequireslong-termplanningb)Typicaltimescalesofcoastalrisk-managementmeasuresHighergreenhousegasemissionsleadtolargerandfastersealevelrise,demandingearlierandstrongerEcosystem-basedadaptation≈15yearsresponses,andreducingthelifetimeofsomeoptionsSediment-basedprotection≈15yearsExample:timingof0.5msealevelriseElevatinghouses≈30yearsveryhighverylow2000210022002300+Protectlevees≈50yearsProtectbarriersLong-living≈100yearssocietalPlannedrelocation≥100yearslegacy2020205021002150KeyIndicativetimeforplanningandimplementationTypicalintendedlifetimeofmeasures80Long-TermClimateandDevelopmentFuturesSection3Figure3.4:Observedandprojectedglobalmeansealevelchangeanditsimpacts,andtimescalesofcoastalriskmanagement.Panel(a):Globalmeansealevelchangeinmetresrelativeto1900.Thehistoricalchanges(black)areobservedbytidegaugesbefore1992andaltimetersafterwards.Thefuturechangesto2100andfor2150(colouredlinesandshading)areassessedconsistentlywithobservationalconstraintsbasedonemulationofCMIP,ice-sheet,andglaciermodels,andmedianvaluesandlikelyrangesareshownfortheconsideredscenarios.Relativeto1995-2014,thelikelyglobalmeansealevelriseby2050isbetween0.15to0.23mintheverylowGHGemissionsscenario(SSP1-1.9)and0.20to0.29mintheveryhighGHGemissionsscenario(SSP5-8.5);by2100between0.28to0.55munderSSP1-1.9and0.63to1.01munderSSP5-8.5;andby2150between0.37to0.86munderSSP1-1.9and0.98to1.88munderSSP5-8.5(mediumconﬁdence).Changesrelativeto1900arecalculatedbyadding0.158m(observedglobalmeansealevelrisefrom1900to1995-2014)tosimulatedchangesrelativeto1995-2014.Thefuturechangesto2300(bars)arebasedonliteratureassessment,representingthe17th–83rdpercentilerangeforSSP1-2.6(0.3to3.1m)andSSP5-8.5(1.7to6.8m).Reddashedlines:Low-likelihood,high-impactstoryline,includingicesheetinstabilityprocesses.Theseindicatethepotentialimpactofdeeplyuncertainprocesses,andshowthe83rdpercentileofSSP5-8.5projectionsthatincludelow-likelihood,high-impactprocessesthatcannotberuledout;becauseoflowconﬁdenceinprojectionsoftheseprocesses,thisisnotpartofalikelyrange.IPCCAR6globalandregionalsealevelprojectionsarehostedathttps://sealevel.nasa.gov/ipcc-ar6-sea-level-projection-tool.Thelow-lyingcoastalzoneiscurrentlyhometoaround896millionpeople(nearly11%ofthe2020globalpopulation),projectedtoreachmorethanonebillionby2050acrossallﬁveSSPs.Panel(b):Typicaltimescalesfortheplanning,implementation(dashedbars)andoperationallifetimeofcurrentcoastalrisk-managementmeasures(bluebars).Higherratesofsealevelrisedemandearlierandstrongerresponsesandreducethelifetimeofmeasures(inset).Asthescaleandpaceofsealevelriseacceleratesbeyond2050,long-termadjustmentsmayinsomelocationsbebeyondthelimitsofcurrentadaptationoptionsandforsomesmallislandsandlow-lyingcoastscouldbeanexistentialrisk.{WGISPMB.5,WGIC.2.5,WGIFigureSPM.8,WGI9.6;WGIISPMB.4.5,WGIIB.5.2,WGIIC.2.8,WGIID.3.3,WGIITS.D.7,WGIICross-ChapterBoxSLR}(Cross-SectionBox.2)81Section33.3MitigationPathwaysLimitinghuman-causedglobalwarmingrequiresnetzeroanthropogenicCO2emissions.Pathwaysconsistentwith1.5°Cand2°Ccarbonbudgetsimplyrapid,deep,andinmostcasesimmediateGHGemissionreductionsinallsectors(highconﬁdence).Exceedingawarminglevelandreturning(i.e.overshoot)impliesincreasedrisksandpotentialirreversibleimpacts;achievingandsustainingglobalnetnegativeCO2emissionswouldreducewarming(highconﬁdence).SectioSnec3tion13.3.1RemainingCarbonBudgetsIftheannualCO2emissionsbetween2020–2030stayed,onaverage,atthesamelevelas2019,theresultingcumulativeemissionswouldLimitingglobaltemperatureincreasetoaspeciﬁclevelrequiresalmostexhausttheremainingcarbonbudgetfor1.5°C(50%),andlimitingcumulativenetCO2emissionstowithinaﬁnitecarbonexhaustmorethanathirdoftheremainingcarbonbudgetfor2°Cbudget126,alongwithstrongreductionsinotherGHGs.Forevery(67%)(Figure3.5).Basedoncentralestimatesonly,historicalcumulative1000GtCO2emittedbyhumanactivity,globalmeantemperaturerisesnetCO2emissionsbetween1850and2019(2400±240GtCO2)amountbylikely0.27°Cto0.63°C(bestestimateof0.45°C).Thisrelationshiptoaboutfour-ﬁfths131ofthetotalcarbonbudgetfora50%probabilityofimpliesthatthereisaﬁnitecarbonbudgetthatcannotbeexceededinlimitingglobalwarmingto1.5°C(centralestimateabout2900GtCO2)andordertolimitwarmingtoanygivenlevel.{WGISPMD.1,WGISPMD.1.1;toabouttwo-thirds132ofthetotalcarbonbudgetfora67%probabilitySR1.5SPMC.1.3}(Figure3.5)tolimitglobalwarmingto2°C(centralestimateabout3550GtCO2).{WGITableSPM.2;WGIIISPMB.1.3,WGIIITable2.1}Thebestestimatesoftheremainingcarbonbudget(RCB)fromthebeginningof2020forlimitingwarmingto1.5°Cwitha50%InscenarioswithincreasingCO2emissions,thelandandoceanlikelihood127isestimatedtobe500GtCO2;for2°C(67%likelihood)carbonsinksareprojectedtobelesseffectiveatslowingthethisis1150GtCO2.128RemainingcarbonbudgetshavebeenquantiﬁedaccumulationofCO2intheatmosphere(highconﬁdence).WhilebasedontheassessedvalueofTCREanditsuncertainty,estimatesofnaturallandandoceancarbonsinksareprojectedtotakeup,inabsolutehistoricalwarming,climatesystemfeedbackssuchasemissionsfromterms,aprogressivelylargeramountofCO2underhighercomparedtothawingpermafrost,andtheglobalsurfacetemperaturechangeafterlowerCO2emissionsscenarios,theybecomelesseffective,thatis,theglobalanthropogenicCO2emissionsreachnetzero,aswellasvariationsproportionofemissionstakenupbylandandoceandecreaseswithinprojectedwarmingfromnon-CO2emissionsdueinparttomitigationincreasingcumulativenetCO2emissions(highconﬁdence).Additionalaction.Thestrongerthereductionsinnon-CO2emissionsthelowertheecosystemresponsestowarmingnotyetfullyincludedinclimatemodels,resultingtemperaturesareforagivenRCBorthelargerRCBforthesuchasGHGﬂuxesfromwetlands,permafrostthaw,andwildﬁres,sameleveloftemperaturechange.Forinstance,theRCBforlimitingwouldfurtherincreaseconcentrationsofthesegasesintheatmospherewarmingto1.5°Cwitha50%likelihoodcouldvarybetween300to(highconﬁdence).InscenarioswhereCO2concentrationspeakand600GtCO2dependingonnon-CO2warming129.Limitingwarmingto2°Cdeclineduringthe21stcentury,thelandandoceanbegintotakeuplesswitha67%(or83%)likelihoodwouldimplyaRCBof1150(900)GtCO2carboninresponsetodecliningatmosphericCO2concentrations(highfromthebeginningof2020.Tostaybelow2°Cwitha50%likelihood,conﬁdence)andturnintoaweaknetsourceby2100intheverylowtheRCBishigher,i.e.,1350GtCO2130.{WGISPMD.1.2,WGITableSPM.2;GHGemissionsscenario(mediumconfidence)133.{WGISPMB.4,WGIIIBoxSPM.1,WGIIIBox3.4;SR1.5SPMC.1.3}WGISPMB.4.1,WGISPMB.4.2,WGISPMB.4.3}126SeeAnnexI:Glossary.127ThislikelihoodisbasedontheuncertaintyintransientclimateresponsetocumulativenetCO2emissionsandadditionalEarthsystemfeedbacksandprovidestheprobabilitythatglobalwarmingwillnotexceedthetemperaturelevelsspeciﬁed.{WGITableSPM.1}128Globaldatabasesmakedifferentchoicesaboutwhichemissionsandremovalsoccurringonlandareconsideredanthropogenic.MostcountriesreporttheiranthropogeniclandCO2ﬂuxesincludingﬂuxesduetohuman-causedenvironmentalchange(e.g.,CO2fertilisation)on‘managed’landintheirNationalGHGinventories.Usingemissionsestimatesbasedontheseinventories,theremainingcarbonbudgetsmustbecorrespondinglyreduced.{WGIIISPMFootnote9,WGIIITS.3,WGIIICross-ChapterBox6}129ThecentralcaseRCBassumesfuturenon-CO2warming(thenetadditionalcontributionofaerosolsandnon-CO2GHG)ofaround0.1°Cabove2010–2019inlinewithstringentmitigationscenarios.Ifadditionalnon-CO2warmingishigher,theRCBforlimitingwarmingto1.5°Cwitha50%likelihoodshrinkstoaround300GtCO2.If,however,additionalnon-CO2warmingislimitedtoonly0.05°C(viastrongerreductionsofCH4andN2Othroughacombinationofdeepstructuralandbehaviouralchanges,e.g.,dietarychanges),theRCBcouldbearound600GtCO2for1.5°Cwarming.{WGITableSPM.2,WGIBoxTS.7;WGIIIBox3.4}130Whenadjustedforemissionssincepreviousreports,theseRCBestimatesaresimilartoSR1.5butlargerthanAR5valuesduetomethodologicalimprovements.{WGISPMD.1.3}131Uncertaintiesfortotalcarbonbudgetshavenotbeenassessedandcouldaffectthespeciﬁccalculatedfractions.132Seefootnote131.133TheseprojectedadjustmentsofcarbonsinkstostabilisationordeclineofatmosphericCO2concentrationsareaccountedforincalculationsofremainingcarbonbudgets.{WGISPMfootnote32}82Long-TermClimateandDevelopmentFuturesRemainingcarbonbudgetstolimitwarmingto1.5°Ccouldsoonbeexhausted,andthosefor2°ClargelydepletedRemainingcarbonbudgetsaresimilartoemissionsfromuseofexistingandplannedfossilfuelinfrastructure,withoutadditionalabatement2020Carbonbudgetsa)Carbonbudgetsandemissions1.5°C2°C(>50%)(83%)CumulativeCO2emissions(GtCO2)historicalsince20200100020000500100015002000Historicalemissions1850-2019Remaining1.5°C(>50%chance)thislineindicatescarbonbudgets2°C(83%chance)maximumemissionstostaywithin2°C2°C(>67%chance)ofwarming(with83%chance)2020–2030CO2emissionsExistingassumingconstantat2019levelExistingandLifetimeemissionsfromfossilfuelinfrastructurewithoutadditionalabatement,plannedifhistoricaloperatingpatternsaremaintainedEverytonofCO2addstoglobalwarmingdierentemissionsscenariosandtheirb)CumulativeCO2emissionsandwarminguntil2050rangesofwarming°C3theseemissionsdeterminehowSSP5-8.5muchwarmingwewillexperienceSSP3-7.0SSP2-4.5Section32.5Warmingsince1850-1900SSP1-2.62SSP1-1.91.51Historicalglobalwarming0.5010002000300040004500CumulativeCO2emissions(GtCO2)since1850–0.5Figure3.5:Cumulativepast,projected,andcommittedemissions,andassociatedglobaltemperaturechanges.Panel(a)Assessedremainingcarbonbudgetstolimitwarmingmorelikelythannotto1.5°C,to2°Cwitha83%and67%likelihood,comparedtocumulativeemissionscorrespondingtoconstant2019emissionsuntil2030,existingandplannedfossilfuelinfrastructures(inGtCO2).Forremainingcarbonbudgets,thinlinesindicatetheuncertaintyduetothecontributionofnon-CO2warming.Forlifetimeemissionsfromfossilfuelinfrastructure,thinlinesindicatetheassessedsensitivityrange.Panel(b)RelationshipbetweencumulativeCO2emissionsandtheincreaseinglobalsurfacetemperature.Historicaldata(thinblackline)showshistoricalCO2emissionsversusobservedglobalsurfacetemperatureincreaserelativetotheperiod1850-1900.Thegreyrangewithitscentrallineshowsacorrespondingestimateofthehuman-causedshareofhistoricalwarming.Colouredareasshowtheassessedverylikelyrangeofglobalsurfacetemperatureprojections,andthickcolouredcentrallinesshowthemedianestimateasafunctionofcumulativeCO2emissionsfortheselectedscenariosSSP1-1.9,SSP1-2.6,SSP2-4.5,SSP3-7.0,andSSP5-8.5.Projectionsuntil2050usethecumulativeCO2emissionsofeachrespectivescenario,andtheprojectedglobalwarmingincludesthecontributionfromallanthropogenicforcers.{WGISPMD.1,WGIFigureSPM.10,WGITableSPM.2;WGIIISPMB.1,WGIIISPMB.7,WGIII2.7;SR1.5SPMC.1.3}83Section3Table3.1:Keycharacteristicsofthemodelledglobalemissionspathways.SummaryofprojectedCO2andGHGemissions,projectednetzerotimingsandtheresultingglobalwarmingoutcomes.Pathwaysarecategorised(columns),accordingtotheirlikelihoodoflimitingwarmingtodifferentpeakwarminglevels(ifpeaktemperatureoccursbefore2100)and2100warminglevels.Valuesshownareforthemedian[p50]and5–95thpercentiles[p5–p95],notingthatnotallpathwaysachievenetzeroCO2orGHGs.{WGIIITableSPM.2}CategoryModelledglobalemissionsC1C1aC1bC2C3C3aC3bC4C5C6pathwayscategorisedby[97][50][47][133][311][204][97](2)projectedglobalwarming[159][212][97]levels(GWL).Detailedlimit…………p50[#pathways]likelihooddefinitionsarewarmingwithwithoutreturnlimitwithNDCslimitlimitlimit[p5-p95](1)providedinSPMBox1.to1.5°CnetzeronetzerowarmingwarmingactionuntilwarmingwarmingwarmingCategory/Thefiveillustrativescenarios(>50%)GHGsto1.5°Cstarting2030to2.5°Csubset(SSPx-yy)consideredbyAR6withnoGHGs(>50%)to2°Cin2020to2°C(>50%)to3°ClabelWGIandtheIllustrative(>67%)(>50%)(>50%)(Mitigation)PathwaysorafteraassessedinWGIIIarelimitedhighalignedwiththetempera-overshootturecategoriesandareovershootindicatedinaseparatecolumn.Globalemissionpathwayscontainregionallydifferentiatedinformation.Thisassessmentfocusesontheirglobalcharacteristics.GHGemissions2030ProjectedmedianGHG43414823212751062reductions2040emissionsreductionsof[34-60][31-59][35-61][0-44][1-42][13-45][0-14][0-27]from2019(%)(3)2050pathwaysintheyearacross[-1to18][-10to11]thescenarioscomparedto6966705546474631modelled2019,withthe[58-90][58-89][62-87][40-71][34-63][35-63][34-63][20-5]1835th-95thpercentilein[4-33][-14to14]brackets.Negativenumbers8485847564636849indicateincreasein[73-98][72-100][76-93][62-91][53-77][52-76][56-83][35-65]295emissionscomparedto2019[11-48][-2to18]Emissionsmilestones(4)NetzeroMedian5-yearintervalsat2050-2055(100%)2055-20602070-20752070-20752065-20702080-2085...-...noCO2whichprojectedCO2&GHG[2035-2070](41%)net-zeroemissionsofpathwaysin(100%)(93%)(91%)(97%)(86%)(%netzerothiscategoryreachnet-zero,[2080-...]pathways)withthe5th-95thpercentile[2045-2070][2055-...][2055-...][2055-2090][2065-...]intervalinsquarebrackets.NetzeroPercentageofnetzero2095-21002070-2075...-...2070-2075...-......-......-......-......-...noGHGspathwaysisdenotedin(0%)(87%)(30%)(24%)(41%)(31%)(12%)net-zeroroundbrackets.(52%)(100%)[2080-...](5)Threedots(…)denotesnet[...-...][2055-...][2075-...][2075-...][2075-...][2090-...]zeronotreachedforthat[2050-...][2050-2090](%netzeropercentile.pathways)CumulativeCO22020toMediancumulativenetCO251055046072089086091012101780noemissions[GtCO2](6)netzeroemissionsacrossthe[330-710][340-760][320-590][530-930]projectedscenariosinthis[640-1160][640-1180][720-1150][970-1490][1400-2360]net-zeroCO2categoryuntilreaching320160360SectioSnec3tion1net-zerooruntil2100,with[-210-570][-220-620][10-540]4008007908001160178027902020–the5th-95thpercentile[-90-620]2100intervalinsquarebrackets.[510-1140][480-1150][560-1050][700-1490][1260-2360][2440-3520]GlobalmeanatpeakProjectedtemperature1.61.61.61.71.71.71.81.92.2notemperaturewarmingchangeofpathwaysinthis[1.4-1.6][1.4-1.6][1.5-1.6][1.5-1.8][1.6-1.8][1.6-1.8][1.6-1.8][1.7-2.0][1.9-2.5]peakingchanges50%category(50%probabilityby2100probability(°C)2100acrosstherangeofclimate1.31.21.41.41.6uncertainties),relativeto[1.1-1.5][1.1-1.4][1.3-1.5][1.2-1.5]1.61.6[1.5-1.7]1.82.12.71850-1900,atpeak[1.5-1.8][1.5-1.8][1.5-2.0][1.9-2.5][2.4-2.9]warmingandin2100,for38372417themedianvalueacrossthe[34-60][33-56][15-42][12-35]scenariosandthe5th-95thpercentileintervalinsquare90898273brackets.[85-97][87-96][71-93][67-87]Likelihoodofpeak<1.5°C381001001002021991140globalwarmingstaying<2.0°C[33-58][99-100][99-100][99-100][13-41][14-42][98-99][7-22]below(%)<3.0°C[0-10]Likelih[0o-o0]d9059Medianlikelihoodthatthe[86-97][50-77]ofpeakprojectedpathwaysinthiscategorystaybelowagiven10076789837globa8lglobalwarminglevel,with[99-100][68-91][69-91][95-99]warmingthe5th-95thpercentileintervalinsquarebrackets.[18-59]stay[i2n-g18]below(%)o991009171[98-100][98-100][83-98][53-88]1DetailedexplanationsontheTableareprovidedinWGIIIBoxSPM.1andWGIIITableSPM.2.TherelationshipbetweenthetemperaturecategoriesandSSP/RCPsisdiscussedinCross-SectionBox.2.Valuesinthetablerefertothe50thand[5–95th]percentilevaluesacrossthepathwaysfallingwithinagivencategoryasdeﬁnedinWGIIIBoxSPM.1.Thethreedots(…)signdenotesthatthevaluecannotbegiven(asthevalueisafter2100or,fornetzero,netzeroisnotreached).BasedontheassessmentofclimateemulatorsinAR6WGI(Chapter7,Box7.1),twoclimateemulatorswereusedfortheprobabilisticassessmentoftheresultingwarmingofthepathways.Forthe‘TemperatureChange’and‘Likelihood’columns,thenon-bracketedvaluesrepresentthe50thpercentileacrossthepathwaysinthatcategoryandthemedian[50thpercentile]acrossthewarmingestimatesoftheprobabilisticMAGICCclimatemodelemulator.Forthebracketedrangesinthe“likelihood”column,themedianwarmingforeverypathwayinthatcategoryiscalculatedforeachofthetwoclimatemodelemulators(MAGICCandFaIR).Theserangescoverboththeuncertaintyoftheemissionspathwaysaswellastheclimateemulators’uncertainty.Allglobalwarminglevelsarerelativeto1850-1900.2C3pathwaysaresub-categorisedaccordingtothetimingofpolicyactiontomatchtheemissionspathwaysinWGIIIFigureSPM.4.3Globalemissionreductionsinmitigationpathwaysarereportedonapathway-by-pathwaybasisrelativetoharmonisedmodelledglobalemissionsin2019ratherthan84Long-TermClimateandDevelopmentFuturestheglobalemissionsreportedinWGIIISPMSectionBandWGIIIChapter2;thisensuresinternalconsistencyinassumptionsaboutemissionsourcesandactivities,aswellasconsistencywithtemperatureprojectionsbasedonthephysicalclimatescienceassessmentbyWGI(seeWGIIISPMFootnote49).Negativevalues(e.g.,inC5,C6)representanincreaseinemissions.ThemodelledGHGemissionsin2019are55[53–58]GtCO2-eq,thuswithintheuncertaintyrangesofestimatesfor2019emissions[53-66]GtCO2-eq(see2.1.1).4Emissionsmilestonesareprovidedfor5-yearintervalsinordertobeconsistentwiththeunderlying5-yeartime-stepdataofthemodelledpathways.Rangesinsquarebracketsunderneathrefertotherangeacrossthepathways,comprisingthelowerboundofthe5thpercentile5-yearintervalandtheupperboundofthe95thpercentile5-yearinterval.Numbersinroundbracketssignifythefractionofpathwaysthatreachspeciﬁcmilestonesoverthe21stcentury.Percentilesreportedacrossallpathwaysinthatcategoryincludethosethatdonotreachnetzerobefore2100.5ForcaseswheremodelsdonotreportallGHGs,missingGHGspeciesareinﬁlledandaggregatedintoaKyotobasketofGHGemissionsinCO2-eqdeﬁnedbythe100-yearglobalwarmingpotential.Foreachpathway,reportingofCO2,CH4,andN2Oemissionswastheminimumrequiredfortheassessmentoftheclimateresponseandtheassignmenttoaclimatecategory.Emissionspathwayswithoutclimateassessmentarenotincludedintherangespresentedhere.SeeWGIIIAnnexIII.II.5.6Cumulativeemissionsarecalculatedfromthestartof2020tothetimeofnetzeroand2100,respectively.TheyarebasedonharmonisednetCO2emissions,ensuringconsistencywiththeWGIassessmentoftheremainingcarbonbudget.{WGIIIBox3.4,WGIIISPMFootnote50}3.3.2NetZeroEmissions:TimingandImplicationsnetzeroGHG,counterbalancedbynetnegativeCO2emissions.Asaresult,netzeroCO2wouldbereachedbeforenetzeroGHGsFromaphysicalscienceperspective,limitinghuman-caused(highconﬁdence).{WGIIISPMC.2,WGIIISPMC.2.3,WGIIISPMC.2.4,globalwarmingtoaspeciﬁclevelrequireslimitingcumulativeWGIIITableSPM.2,WGIII3.3}(Figure3.6)CO2emissions,reachingnetzeroornetnegativeCO2emissions,alongwithstrongreductionsofotherGHGemissionsSection3(seeCross-SectionBox.1).GlobalmodelledpathwaysthatreachandsustainnetzeroGHGemissionsareprojectedtoresultinagradualdeclineinsurfacetemperature(highconﬁdence).ReachingnetzeroGHGemissionsprimarilyrequiresdeepreductionsinCO2,methane,andotherGHGemissions,andimpliesnetnegativeCO2emissions.134Carbondioxideremoval(CDR)willbenecessarytoachievenetnegativeCO2emissions135.AchievingglobalnetzeroCO2emissions,withremaininganthropogenicCO2emissionsbalancedbydurablystoredCO2fromanthropogenicremoval,isarequirementtostabiliseCO2-inducedglobalsurfacetemperatureincrease(see3.3.3)(highconﬁdence).ThisisdifferentfromachievingnetzeroGHGemissions,wheremetric-weightedanthropogenicGHGemissions(seeCross-SectionBox.1)equalCO2removal(highconﬁdence).EmissionspathwaysthatreachandsustainnetzeroGHGemissionsdeﬁnedbythe100-yearglobalwarmingpotentialimplynetnegativeCO2emissionsandareprojectedtoresultinagradualdeclineinsurfacetemperatureafteranearlierpeak(highconﬁdence).WhilereachingnetzeroCO2ornetzeroGHGemissionsrequiresdeepandrapidreductionsingrossemissions,thedeploymentofCDRtocounterbalancehard-to-abateresidualemissions(e.g.,someemissionsfromagriculture,aviation,shipping,andindustrialprocesses)isunavoidable(highconﬁdence).{WGISPMD.1,WGISPMD.1.1,WGISPMD.1.8;WGIIISPMC.2,WGIIISPMC.3,WGIIISPMC.11,WGIIIBoxTS.6;SR1.5SPMA.2.2}Inmodelledpathways,thetimingofnetzeroCO2emissions,followedbynetzeroGHGemissions,dependsonseveralvariables,includingthedesiredclimateoutcome,themitigationstrategyandthegasescovered(highconﬁdence).GlobalnetzeroCO2emissionsarereachedintheearly2050sinpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot,andaroundtheearly2070sinpathwaysthatlimitwarmingto2°C(>67%).Whilenon-CO2GHGemissionsarestronglyreducedinallpathwaysthatlimitwarmingto2°C(>67%)orlower,residualemissionsofCH4andN2OandF-gasesofabout8[5–11]GtCO2-eqyr-1remainatthetimeof134NetzeroGHGemissionsdeﬁnedbythe100-yearglobalwarmingpotential.Seefootnote70.135SeeSection3.3.3and3.4.1.85Section3Globalmodelledpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershootreachnetzeroCO2emissionsaround2050Totalgreenhousegases(GHG)reachnetzerolatera)Whilekeepingwarmingto1.5°Cb)Whilekeepingwarmingto2°C(>67%)(>50%)withnoorlimitedovershootGigatonsofCO2equivalentperyear(GtCO2-eq/yr)60Policiesinplacein202060Policiesinplacein2020GHGsreachnetzeroGHGlaterthanCO2GHG4040CO2HistoricalCO2Historical2020CH4netzeroCH4netzero00200020202040206020802100200020202040206020802100c)TimingfornetzeroSectioSnec3tion1GHGnotallCO2scenariosreachnetzeroGHGby2100200020202040206020802100200020202040206020802100Figure3.6:TotalGHG,CO2andCH4emissionsandtimingofreachingnetzeroindifferentmitigationpathways.Toprow:GHG,CO2andCH4emissionsovertime(inGtCO2eq)withhistoricalemissions,projectedemissionsinlinewithpoliciesimplementeduntiltheendof2020(grey),andpathwaysconsistentwithtemperaturegoalsincolour(blue,purple,andbrown,respectively).Panel(a)(left)showspathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot(C1)andPanel(b)(right)showspathwaysthatlimitwarmingto2°C(>67%)(C3).Bottomrow:Panel(c)showsmedian(verticalline),likely(bar)andverylikely(thinlines)timingofreachingnetzeroGHGandCO2emissionsforglobalmodelledpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot(C1)(left)or2°C(>67%)(C3)(right).{WGIIIFigureSPM.5}3.3.3SectoralContributionstoMitigationinfrastructuredesignandaccess.(highconﬁdence){WGIIISPMC.3,WGIIISPMC.5,WGIIISPMC.6,WGIIISPMC.7.3,WGIIISPMC.8,Allglobalmodelledpathwaysthatlimitwarmingto2°C(>67%)orWGIIISPMC.10.2}lowerby2100involverapidanddeepandinmostcasesimmediateGHGemissionsreductionsinallsectors(seealso4.1,4.5).ReductionsGlobalmodelledmitigationpathwaysreachingnetzeroCO2andinGHGemissionsinindustry,transport,buildings,andurbanareasGHGemissionsincludetransitioningfromfossilfuelswithoutcanbeachievedthroughacombinationofenergyefﬁciencyandcarboncaptureandstorage(CCS)toverylow-orzero-carbonconservationandatransitiontolow-GHGtechnologiesandenergyenergysources,suchasrenewablesorfossilfuelswithCCS,carriers(seealso4.5,Figure4.4).Socio-culturaloptionsandbehaviouraldemand-sidemeasuresandimprovingefﬁciency,reducingchangecanreduceglobalGHGemissionsofend-usesectors,withmostnon-CO2GHGemissions,andCDR136.Inglobalmodelledpathwaysofthepotentialindevelopedcountries,ifcombinedwithimprovedthatlimitwarmingto2°Corbelow,almostallelectricityissupplied136CCSisanoptiontoreduceemissionsfromlarge-scalefossil-basedenergyandindustrysourcesprovidedgeologicalstorageisavailable.WhenCO2iscaptureddirectlyfromtheatmosphere(DACCS),orfrombiomass(BECCS),CCSprovidesthestoragecomponentoftheseCDRmethods.CO2captureandsubsurfaceinjectionisamaturetechnologyforgasprocessingandenhancedoilrecovery.Incontrasttotheoilandgassector,CCSislessmatureinthepowersector,aswellasincementandchemicalsproduction,whereitisacriticalmitigationoption.Thetechnicalgeologicalstoragecapacityisestimatedtobeontheorderof1000GtCO2,whichismorethantheCO2storagerequirementsthrough2100tolimitglobalwarmingto1.5°C,althoughtheregionalavailabilityofgeologicalstoragecouldbealimitingfactor.Ifthegeologicalstoragesiteisappropriatelyselectedandmanaged,itisestimatedthattheCO2canbepermanentlyisolatedfromtheatmosphere.ImplementationofCCScurrentlyfacestechnological,economic,institutional,ecologicalenvironmentalandsocio-culturalbarriers.Currently,globalratesofCCSdeploymentarefarbelowthoseinmodelledpathwayslimitingglobalwarmingto1.5°Cto2°C.Enablingconditionssuchaspolicyinstruments,greaterpublicsupportandtechnologicalinnovationcouldreducethesebarriers.(highconﬁdence){WGIIISPMC.4.6}86Long-TermClimateandDevelopmentFuturesfromzeroorlow-carbonsourcesin2050,suchasrenewablesor3.3.4OvershootPathways:IncreasedRisksandOtherSection3fossilfuelswithCO2captureandstorage,combinedwithincreasedImplicationselectriﬁcationofenergydemand.Suchpathwaysmeetenergyservicedemandwithrelativelylowenergyuse,throughe.g.,enhancedenergyExceedingaspeciﬁcremainingcarbonbudgetresultsinefﬁciencyandbehaviouralchangesandincreasedelectriﬁcationofhigherglobalwarming.Achievingandsustainingnetnegativeenergyenduse.ModelledglobalpathwayslimitingglobalwarmingtoglobalCO2emissionscouldreversetheresultingtemperature1.5°C(>50%)withnoorlimitedovershootgenerallyimplementsuchexceedance(highconﬁdence).Continuedreductionsinemissionsofchangesfasterthanpathwayslimitingglobalwarmingto2°C(>67%).short-livedclimateforcers,particularlymethane,afterpeaktemperature(highconﬁdence){WGIIISPMC.3,WGIIISPMC.3.2,WGIIISPMC.4,hasbeenreached,wouldalsofurtherreducewarming(highconﬁdence).WGIIITS.4.2;SR1.5SPMC.2.2}Onlyasmallnumberofthemostambitiousglobalmodelledpathwayslimitglobalwarmingto1.5°C(>50%)withoutovershoot.{WGISPMD.1.1,AFOLUmitigationoptions,whensustainablyimplemented,canWGISPMD.1.6,WGISPMD.1.7;WGIIITS.4.2}deliverlarge-scaleGHGemissionreductionsandenhancedCO2removal;however,barrierstoimplementationandtrade-offsOvershootofawarminglevelresultsinmoreadverseimpacts,somemayresultfromtheimpactsofclimatechange,competingirreversible,andadditionalrisksforhumanandnaturalsystemsdemandsonland,conﬂictswithfoodsecurityandlivelihoods,comparedtostayingbelowthatwarminglevel,withrisksgrowingthecomplexityoflandownershipandmanagementsystems,withthemagnitudeanddurationofovershoot(highconﬁdence).andculturalaspects(see3.4.1).AllassessedmodelledpathwaysComparedtopathwayswithoutovershoot,societiesandecosystemsthatlimitwarmingto2°C(>67%)orlowerby2100includeland-basedwouldbeexposedtogreaterandmorewidespreadchangesinclimaticmitigationandland-usechange,withmostincludingdifferentimpact-drivers,suchasextremeheatandextremeprecipitation,withcombinationsofreforestation,afforestation,reduceddeforestation,andincreasingriskstoinfrastructure,low-lyingcoastalsettlements,andbioenergy.However,accumulatedcarboninvegetationandsoilsisatassociatedlivelihoods(highconﬁdence).Overshooting1.5°Cwillresultriskfromfutureloss(orsinkreversal)triggeredbyclimatechangeandinirreversibleadverseimpactsoncertainecosystemswithlowresilience,disturbancessuchasﬂood,drought,ﬁre,orpestoutbreaks,orfuturesuchaspolar,mountain,andcoastalecosystems,impactedbyice-sheetpoormanagement.(highconﬁdence){WGISPMB.4.3;WGIISPMB.2.3,melt,glaciermelt,orbyacceleratingandhighercommittedsealevelWGIISPMB.5.4;WGIIISPMC.9,WGIIISPMC.11.3,WGIIISPMD.2.3,rise(highconﬁdence).Overshootincreasestherisksofsevereimpacts,WGIIITS.4.2,3.4;SR1.5SPMC.2.5;SRCCLSPMB.1.4,SRCCLSPMB.3,suchasincreasedwildﬁres,massmortalityoftrees,dryingofpeatlands,SRCCLSPMB.7}thawingofpermafrostandweakeningnaturallandcarbonsinks;suchimpactscouldincreasereleasesofGHGsmakingtemperaturereversalInadditiontodeep,rapid,andsustainedemissionreductions,morechallenging(mediumconﬁdence).{WGISPMC.2,WGISPMC.2.1,CDRcanfulﬁlthreecomplementaryroles:loweringnetCO2WGISPMC.2.3;WGIISPMB.6,WGIISPMB.6.1,WGIISPMB.6.2;SR1.53.6}ornetGHGemissionsinthenearterm;counterbalancing‘hard-to-abate’residualemissions(e.g.,someemissionsfromThelargertheovershoot,themorenetnegativeCO2emissionsneededagriculture,aviation,shipping,industrialprocesses)tohelpreachtoreturntoagivenwarminglevel(highconﬁdence).ReducingglobalnetzeroCO2orGHGemissions,andachievingnetnegativetemperaturebyremovingCO2wouldrequirenetnegativeemissionsofCO2orGHGemissionsifdeployedatlevelsexceedingannual220GtCO2(bestestimate,withalikelyrangeof160to370GtCO2)residualemissions(highconﬁdence).CDRmethodsvaryintermsforeverytenthofadegree(mediumconﬁdence).Modelledpathwaysoftheirmaturity,removalprocess,timescaleofcarbonstorage,storagethatlimitwarmingto1.5°C(>50%)withnoorlimitedovershootreachmedium,mitigationpotential,cost,co-beneﬁts,impactsandrisks,andmedianvaluesofcumulativenetnegativeemissionsof220GtCO2governancerequirements(highconﬁdence).Speciﬁcally,maturityby2100,pathwaysthatreturnwarmingto1.5°C(>50%)afterhighrangesfromlowermaturity(e.g.,oceanalkalinisation)tohigherovershootreachmedianvaluesof360GtCO2(highconﬁdence).137maturity(e.g.,reforestation);removalandstoragepotentialrangesMorerapidreductioninCO2andnon-CO2emissions,particularlyfromlowerpotential(<1GtCO2yr-1,e.g.,bluecarbonmanagement)methane,limitspeakwarminglevelsandreducestherequirementtohigherpotential(>3GtCO2yr-1,e.g.,agroforestry);costsrangefromfornetnegativeCO2emissionsandCDR,therebyreducingfeasibilitylowercost(e.g.,–45to100USDtCO2-1forsoilcarbonsequestration)andsustainabilityconcerns,andsocialandenvironmentalrisks(hightohighercost(e.g.,100to300USDtCO2-1fordirectaircarbondioxideconfidence).{WGISPMD.1.1;WGIIISPMB.6.4,WGIIISPMC.2,captureandstorage)(mediumconﬁdence).EstimatedstoragetimescalesWGIIISPMC.2.2,WGIIITableSPM.2}varyfromdecadestocenturiesformethodsthatstorecarboninvegetationandthroughsoilcarbonmanagement,totenthousandyearsormoreformethodsthatstorecarboningeologicalformations(highconﬁdence).Afforestation,reforestation,improvedforestmanagement,agroforestryandsoilcarbonsequestrationarecurrentlytheonlywidelypracticedCDRmethods(highconﬁdence).MethodsandlevelsofCDRdeploymentinglobalmodelledmitigationpathwaysvarydependingonassumptionsaboutcosts,availabilityandconstraints(highconﬁdence).{WGIIISPMC.3.5,WGIIISPMC.11.1,WGIIISPMC.11.4}137Limitedovershootreferstoexceeding1.5°Cglobalwarmingbyuptoabout0.1°C,highovershootby0.1°Cto0.3°C,inbothcasesforuptoseveraldecades.{WGIIIBoxSPM.1}87Section33.4Long-TermInteractionsBetweenAdaptation,MitigationandSustainableDevelopmentMitigationandadaptationcanleadtosynergiesandtrade-offswithsustainabledevelopment(highconﬁdence).Acceleratedandequitablemitigationandadaptationbringbeneﬁtsfromavoidingdamagesfromclimatechangeandarecriticaltoachievingsustainabledevelopment(highconﬁdence).Climateresilientdevelopment138pathwaysareprogressivelyconstrainedbyeveryincrementoffurtherwarming(veryhighconﬁdence).Thereisarapidlyclosingwindowofopportunitytosecurealiveableandsustainablefutureforall(veryhighconﬁdence).SectioSnec3tion13.4.1Synergiesandtrade-offs,costsandbeneﬁtsModelledpathwaysthatassumeusingresourcesmoreefﬁcientlyorshiftglobaldevelopmenttowardssustainabilityincludefewerchallenges,suchMitigationandadaptationoptionscanleadtosynergiesandasdependenceonCDRandpressureonlandandbiodiversity,andhavetrade-offswithotheraspectsofsustainabledevelopmentthemostpronouncedsynergieswithrespecttosustainabledevelopment(seealsoSection4.6,Figure4.4).Synergiesandtrade-offsdepend(highconﬁdence).{WGIIISPMC.3.6;SR1.5SPMD.4.2}onthepaceandmagnitudeofchangesandthedevelopmentcontextincludinginequalities,withconsiderationofclimatejustice.TheStrengtheningclimatechangemitigationactionentailsmorepotentialoreffectivenessofsomeadaptationandmitigationoptionsrapidtransitionsandhigherup-frontinvestments,butbringsdecreasesasclimatechangeintensiﬁes(seealsoSections3.2,3.3.3,beneﬁtsfromavoidingdamagesfromclimatechangeand4.5).(highconﬁdence){WGIISPMC.2,WGIIFigureSPM.4b;WGIIISPMD.1,reducedadaptationcosts.TheaggregateeffectsofclimatechangeWGIIISPMD.1.2,WGIIITS.5.1,WGIIIFigureSPM.8;SR1.5SPMD.3,mitigationonglobalGDP(excludingdamagesfromclimatechangeandSR1.5SPMD.4;SRCCLSPMB.2,SRCCLSPMB.3,SRCCLSPMD.3.2,adaptationcosts)aresmallcomparedtoglobalprojectedGDPgrowth.SRCCLFigureSPM.3}Projectedestimatesofglobalaggregateneteconomicdamagesandthecostsofadaptationgenerallyincreasewithglobalwarminglevel.Intheenergysector,transitionstolow-emissionsystemswillhave(highconﬁdence){WGIISPMB.4.6,WGIITS.C.10;WGIIISPMC.12.2,multipleco-beneﬁts,includingimprovementsinairqualityandhealth.WGIIISPMC.12.3}Therearepotentialsynergiesbetweensustainabledevelopmentand,forinstance,energyefﬁciencyandrenewableenergy.(highconﬁdence)Cost-beneﬁtanalysisremainslimitedinitsabilitytorepresentall{WGIIISPMC.4.2,WGIIISPMD.1.3}damagesfromclimatechange,includingnon-monetarydamages,ortocapturetheheterogeneousnatureofdamagesandtheriskofForagriculture,land,andfoodsystems,manylandmanagementcatastrophicdamages(highconﬁdence).Evenwithoutaccountingforoptionsanddemand-sideresponseoptions(e.g.,dietarychoices,thesefactorsorfortheco-beneﬁtsofmitigation,theglobalbeneﬁtsreducedpost-harvestlosses,reducedfoodwaste)cancontributetooflimitingwarmingto2°Cexceedthecostofmitigation(mediumeradicatingpovertyandeliminatinghungerwhilepromotinggoodhealthconﬁdence).Thisﬁndingisrobustagainstawiderangeofassumptionsandwell-being,cleanwaterandsanitation,andlifeonland(mediumaboutsocialpreferencesoninequalitiesanddiscountingovertimeconfidence).Incontrast,certainadaptationoptionsthatpromote(mediumconﬁdence).Limitingglobalwarmingto1.5°Cinsteadof2°Cintensificationofproduction,suchasirrigation,mayhavenegativewouldincreasethecostsofmitigation,butalsoincreasethebeneﬁtseffectsonsustainability(e.g.,forbiodiversity,ecosystemservices,intermsofreducedimpactsandrelatedrisks(see3.1.1,3.1.2)andgroundwaterdepletion,andwaterquality)(highconfidence).{WGIIreducedadaptationneeds(highconfidence)140.{WGIISPMB.4,WGIITS.D.5.5;WGIIISPMD.10;SRCCLSPMB.2.3}SPMB.6;WGIIISPMC.12,WGIIISPMC.12.2,WGIIISPMC.12.3WGIIIBoxTS.7;SR1.5SPMB.3,SR1.5SPMB.5,SR1.5SPMB.6}Reforestation,improvedforestmanagement,soilcarbonsequestration,peatlandrestorationandcoastalbluecarbonmanagementareConsideringothersustainabledevelopmentdimensions,suchastheexamplesofCDRmethodsthatcanenhancebiodiversityandecosystempotentiallystrongeconomicbeneﬁtsonhumanhealthfromairqualityfunctions,employmentandlocallivelihoods,dependingoncontext139.improvement,mayenhancetheestimatedbeneﬁtsofmitigationHowever,afforestationorproductionofbiomasscropsforbioenergy(mediumconﬁdence).Theeconomiceffectsofstrengthenedmitigationwithcarbondioxidecaptureandstorageorbiocharcanhaveadverseactionvaryacrossregionsandcountries,dependingnotablyoneconomicsocio-economicandenvironmentalimpacts,includingonbiodiversity,structure,regionalemissionsreductions,policydesignandleveloffoodandwatersecurity,locallivelihoodsandtherightsofIndigenousinternationalcooperation(highconﬁdence).AmbitiousmitigationPeoples,especiallyifimplementedatlargescalesandwherelandpathwaysimplylargeandsometimesdisruptivechangesineconomictenureisinsecure.(highconﬁdence){WGIISPMB.5.4,WGIISPMC.2.4;structure,withimplicationsfornear-termactions(Section4.2),equityWGIIISPMC.11.2;SR1.5SPMC.3.4,SR1.5SPMC.3.5;SRCCLSPMB.3,(Section4.4),sustainability(Section4.6),andﬁnance(Section4.8)SRCCLSPMB.7.3,SRCCLFigureSPM.3}(highconﬁdence).{WGIIISPMC.12.2,WGIIISPMD.3.2,WGIIITS.4.2}138TSheeeAimnnpeaxctIs:,Grliosksssa,rayn.dco-beneﬁtsofCDRdeploymentforecosystems,biodiversityandpeoplewillbehighlyvariabledependingonthemethod,site-speciﬁccontext,139implementationandscale(highconﬁdence).{WGIIISPMC.11.2}139Theimpacts,risks,andco-beneﬁtsofCDRdeploymentforecosystems,biodiversityandpeoplewillbehighlyvariabledependingonthemethod,site-speciﬁccontext,140Timheplevmideenntacetioisntaonodlismcaitleed(htoigmhackoenﬁadseimnciela)r.{rWobGuIsIItScPoMnclCu.s1io1n.2f}orlimitingwarmingto1.5°C.{WGIIISPMfootnote68}140Theevidenceistoolimitedtomakeasimilarrobustconclusionforlimitingwarmingto1.5°C.{WGIIISPMfootnote68}88Long-TermClimateandDevelopmentFutures3.4.2AdvancingIntegratedClimateActionforSustainableclimateresilientdevelopmentprogressivelyhardertoachievebeyondDevelopment1.5°Cwarming(veryhighconﬁdence).{WGIISPMD.1,WGIISPMD.1.1,WGIISPMD.4,WGIISPMD.4.3,WGIISPMD.5.1;WGIIISPMD.1.1}Aninclusive,equitableapproachtointegratingadaptation,mitigationanddevelopmentcanadvancesustainabledevelopmentinthelongThecumulativescientiﬁcevidenceisunequivocal:climatechangeterm(highconﬁdence).Integratedresponsescanharnesssynergiesforisathreattohumanwell-beingandplanetaryhealth(verysustainabledevelopmentandreducetrade-offs(highconﬁdence).Shiftinghighconﬁdence).Anyfurtherdelayinconcertedanticipatorydevelopmentpathwaystowardssustainabilityandadvancingclimateglobalactiononadaptationandmitigationwillmissabriefandresilientdevelopmentisenabledwhengovernments,civilsocietyrapidlyclosingwindowofopportunitytosecurealiveableandandtheprivatesectormakedevelopmentchoicesthatprioritiserisksustainablefutureforall(veryhighconﬁdence).Opportunitiesforreduction,equityandjustice,andwhendecision-makingprocesses,near-termactionareassessedinthefollowingsection.{WGIISPMD.5.3;ﬁnanceandactionsareintegratedacrossgovernancelevels,sectorsWGIIISPMD.1.1}andtimeframes(veryhighconﬁdence)(seealsoFigure4.2).InclusiveprocessesinvolvinglocalknowledgeandIndigenousKnowledgeincreasetheseprospects(highconﬁdence).However,opportunitiesforactiondiffersubstantiallyamongandwithinregions,drivenbyhistoricalandongoingpatternsofdevelopment(veryhighconﬁdence).Acceleratedﬁnancialsupportfordevelopingcountriesiscriticaltoenhancemitigationandadaptationaction(highconﬁdence).{WGIISPMC.5.4,WGIISPMD.1,WGIISPMD.1.1,WGIISPMD.1.2,WGIISPMD.2,WGIISPMD.3,WGIISPMD.5,WGIISPMD.5.1,WGIISPMD.5.2;WGIIISPMD.1,WGIIISPMD.2,WGIIISPMD.2.4,WGIIISPME.2.2,WGIIISPME.2.3,WGIIISPME.5.3,WGIIICross-ChapterBox5}PoliciesthatshiftdevelopmentpathwaystowardssustainabilitySection3canbroadentheportfolioofavailablemitigationandadaptationresponses(mediumconﬁdence).Combiningmitigationwithactiontoshiftdevelopmentpathways,suchasbroadersectoralpolicies,approachesthatinducelifestyleorbehaviourchanges,ﬁnancialregulation,ormacroeconomicpoliciescanovercomebarriersandopenupabroaderrangeofmitigationoptions(highconﬁdence).Integrated,inclusiveplanningandinvestmentineverydaydecision-makingabouturbaninfrastructurecansigniﬁcantlyincreasetheadaptivecapacityofurbanandruralsettlements.CoastalcitiesandsettlementsplayanimportantroleinadvancingclimateresilientdevelopmentduetothehighnumberofpeoplelivingintheLowElevationCoastalZone,theescalatingandclimatecompoundedriskthattheyface,andtheirvitalroleinnationaleconomiesandbeyond(highconﬁdence).{WGIISPM.D.3,WGIISPMD.3.3;WGIIISPME.2,WGIIISPME.2.2;SR1.5SPMD.6}Observedadverseimpactsandrelatedlossesanddamages,projectedrisks,trendsinvulnerability,andadaptationlimitsdemonstratethattransformationforsustainabilityandclimateresilientdevelopmentactionismoreurgentthanpreviouslyassessed(veryhighconﬁdence).ClimateresilientdevelopmentintegratesadaptationandGHGmitigationtoadvancesustainabledevelopmentforall.Climateresilientdevelopmentpathwayshavebeenconstrainedbypastdevelopment,emissionsandclimatechangeandareprogressivelyconstrainedbyeveryincrementofwarming,inparticularbeyond1.5°C(veryhighconﬁdence).Climateresilientdevelopmentwillnotbepossibleinsomeregionsandsub-regionsifglobalwarmingexceeds2°C(mediumconﬁdence).Safeguardingbiodiversityandecosystemsisfundamentaltoclimateresilientdevelopment,butbiodiversityandecosystemserviceshavelimitedcapacitytoadapttoincreasingglobalwarminglevels,making8990Section4Near-TermResponsesinaChangingClimate91Section4Section4:Near-TermResponsesinaChangingClimate4.1TheTimingandUrgencyofClimateActionDeep,rapid,andsustainedmitigationandacceleratedimplementationofadaptationreducestherisksofclimatechangeforhumansandecosystems.Inmodelledpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershootandinthosethatlimitwarmingto2°C(>67%)andassumeimmediateaction,globalGHGemissionsareprojectedtopeakintheearly2020sfollowedbyrapidanddeepreductions.Asadaptationoptionsoftenhavelongimplementationtimes,acceleratedimplementationofadaptation,particularlyinthisdecade,isimportanttocloseadaptationgaps.(highconﬁdence)SectioSnec4tion1ThemagnitudeandrateofclimatechangeandassociatedrisksInmodelledpathwaysthatlimitwarmingto1.5°C(>50%)withdependstronglyonnear-termmitigationandadaptationactionsnoorlimitedovershootandinthosethatlimitwarmingto(veryhighconﬁdence).Globalwarmingismorelikelythannottoreach2°C(>67%),assumingimmediateactions,globalGHGemissions1.5°Cbetween2021and2040evenundertheverylowGHGemissionareprojectedtopeakintheearly2020sfollowedbyrapidandscenarios(SSP1-1.9),andlikelyorverylikelytoexceed1.5°CunderdeepGHGemissionsreductions(highconﬁdence).142Inpathwayshigheremissionsscenarios141.Manyadaptationoptionshavemediumthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot,netorhighfeasibilityupto1.5°C(mediumtohighconﬁdence,dependingglobalGHGemissionsareprojectedtofallby43[34to60]%143belowonoption),buthardlimitstoadaptationhavealreadybeenreached2019levelsby2030,60[49to77]%by2035,69[58to90]%by2040insomeecosystemsandtheeffectivenessofadaptationtoreduceand84[73to98]%by2050(highconﬁdence)(Section2.3.1,Table2.2,climateriskwilldecreasewithincreasingwarming(highconﬁdence).Figure2.5,Table3.1)144.GlobalmodelledpathwaysthatlimitwarmingSocietalchoicesandactionsimplementedinthisdecadedeterminetheto2°C(>67%)havereductionsinGHGemissionsbelow2019levelsextenttowhichmedium-andlong-termpathwayswilldeliverhigherorof21[1to42]%by2030,35[22to55]%by2035,46[34to63]lowerclimateresilientdevelopment(highconﬁdence).Climateresilient%by2040and64[53to77]%by2050145(highconﬁdence).GlobaldevelopmentprospectsareincreasinglylimitedifcurrentgreenhouseGHGemissionsassociatedwithNDCsannouncedpriortoCOP26wouldgasemissionsdonotrapidlydecline,especiallyif1.5°Cglobalwarmingmakeitlikelythatwarmingwouldexceed1.5°C(highconﬁdence)isexceededinthenearterm(highconﬁdence).Withouturgent,effectiveandlimitingwarmingto2°C(>67%)wouldthenimplyarapidandequitableadaptationandmitigationactions,climatechangeaccelerationofemissionreductionsduring2030–2050,aroundincreasinglythreatensthehealthandlivelihoodsofpeoplearound70%fasterthaninpathwayswhereimmediateactionistakentotheglobe,ecosystemhealth,andbiodiversity,withsevereadverselimitwarmingto2°C(>67%)(mediumconﬁdence)(Section2.3.1)consequencesforcurrentandfuturegenerations(highconﬁdence).Continuedinvestmentsinunabatedhigh-emittinginfrastructure146and{WGISPMB.1.3,WGISPMB.5.1,WGISPMB.5.2;WGIISPMA,WGIIlimiteddevelopmentanddeploymentoflow-emittingalternativesSPMB.4,WGIISPMC.2,WGIISPMC.3.3,WGIIFigureSPM.4,WGIISPMpriorto2030wouldactasbarrierstothisaccelerationandincreaseD.1,WGIISPMD.5,WGIIISPMD.1.1SR1.5SPMD.2.2}.(Cross-Sectionfeasibilityrisks(highconfidence).{WGIIISPMB.6.3,WGIII3.5.2,Box.2,Figure2.1,Figure2.3)WGIIISPMB.6,WGIIISPMB.6.,WGIIISPMC.1,WGIIISPMC1.1,WGIIITableSPM.2}(Cross-SectionBox.2)141Inthenearterm(2021–2040),the1.5°CglobalwarminglevelisverylikelytobeexceededundertheveryhighGHGemissionsscenario(SSP5-8.5),likelytobeexceededundertheintermediateandhighGHGemissionsscenarios(SSP2-4.5,SSP3-7.0),morelikelythannottobeexceededunderthelowGHGemissionsscenario(SSP1-2.6)andmorelikelythannottobereachedundertheverylowGHGemissionsscenario(SSP1-1.9).Thebestestimates[andverylikelyranges]ofglobalwarmingforthedifferentscenariosintheneartermare:1.5[1.2to1.7]°C(SSP1-1.9);1.5[1.2to1.8]°C(SSP1-2.6);1.5[1.2to1.8]°C(SSP2-4.5);1.5[1.2to1.8]°C(SSP3-7.0);and1.6[1.3to1.9]°C(SSP5-8.5).{WGISPMB.1.3,WGITableSPM.1}(Cross-SectionBox.2)142Valuesinparenthesesindicatethelikelihoodoflimitingwarmingtothelevelspeciﬁed(seeCross-SectionBox.2).143Medianandverylikelyrange[5thto95thpercentile].{WGIIISPMfootnote30}144ThesenumbersforCO2are48[36to69]%in2030,65[50to96]%in2035,80[61to109]%in2040and99[79to119]%in2050.145ThesenumbersforCO2are22[1to44]%in2030,37[21to59]%in2035,51[36to70]%in2040and73[55to90]%in2050.146Inthiscontext,‘unabatedfossilfuels’referstofossilfuelsproducedandusedwithoutinterventionsthatsubstantiallyreducetheamountofGHGemittedthroughoutthelifecycle;forexample,capturing90%ormoreCO2frompowerplants,or50to80%offugitivemethaneemissionsfromenergysupply.{WGIIISPMfootnote54}92Near-TermResponsesinaChangingClimateAllglobalmodelledpathwaysthatlimitwarmingto2°C(>67%)Section4orlowerby2100involvereductionsinbothnetCO2emissionsandnon-CO2emissions(seeFigure3.6)(highconfidence).Forexample,inpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot,globalCH4(methane)emissionsarereducedby34[21to57]%below2019levelsby2030andby44[31to63]%in2040(highconfidence).GlobalCH4emissionsarereducedby24[9to53]%below2019levelsby2030andby37[20to60]%in2040inmodelledpathwaysthatlimitwarmingto2°Cwithactionstartingin2020(>67%)(highconﬁdence).{WGIIISPMC1.2,WGIIITableSPM.2,WGIII3.3;SR1.5SPMC.1,SR1.5SPMC.1.2}(Cross-SectionBox.2)Allglobalmodelledpathwaysthatlimitwarmingto2°C(>67%)orlowerby2100involveGHGemissionreductionsinallsectors(highconﬁdence).Thecontributionsofdifferentsectorsvaryacrossmodelledmitigationpathways.Inmostglobalmodelledmitigationpathways,emissionsfromland-use,land-usechangeandforestry,viareforestationandreduceddeforestation,andfromtheenergysupplysectorreachnetzeroCO2emissionsearlierthanthebuildings,industryandtransportsectors(Figure4.1).Strategiescanrelyoncombinationsofdifferentoptions(Figure4.1,Section4.5),butdoinglessinonesectorneedstobecompensatedbyfurtherreductionsinothersectorsifwarmingistobelimited.(highconﬁdence){WGIIISPMC.3,WGIIISPMC.3.1,WGIIISPM3.2,WGIIISPMC.3.3}(Cross-SectionBox.2)Withoutrapid,deepandsustainedmitigationandacceleratedadaptationactions,lossesanddamageswillcontinuetoincrease,includingprojectedadverseimpactsinAfrica,LDCs,SIDS,CentralandSouthAmerica147,AsiaandtheArctic,andwilldisproportionatelyaffectthemostvulnerablepopulations(highconﬁdence).{WGIISPMC.3.5,WGIISPMB.2.4,WGII12.2,WGII10.Box10.6,WGIITSD.7.5,WGIICross-ChapterBox6ES,WGIIGlobaltoRegionalAtlasAnnexA1.15,WGIIGlobaltoRegionalAtlasAnnexA1.27;SR1.5SPMB.5.3,SR1.5SPMB.5.7;SRCCLA.5.6}(Figure3.2;Figure3.3)147ThesouthernpartofMexicoisincludedintheclimaticsubregionSouthCentralAmerica(SCA)forWGI.MexicoisassessedaspartofNorthAmericaforWGII.TheclimatechangeliteraturefortheSCAregionoccasionallyincludesMexico,andinthosecasesWGIIassessmentmakesreferencetoLatinAmerica.MexicoisconsideredpartofLatinAmericaandtheCaribbeanforWGIII.{WGII12.1.1,WGIIIAII.1.1}93Section4PercentagereductioninCO2emissionsrelativeto2015ThetransitiontowardsnetzeroCO2willhavedifferentpaceacrossdifferentsectorsCO2emissionsfromtheelectricity/fossilfuelindustriessectorandland-usechangegenerallyreachnetzeroearlierthanothersectorsa)Sectoralemissionsinpathwaysthatlimitwarmingto1.5°Cpathwaysfor2°Creachnetzerosomewhatlater0%−25%Non-CO2emissionshalfwayTransport,industryandbuildingstonetzero−75%SectioSnec4tion1−100%netzeroEnergysupply(includingelectricity)−125%202020302040Land-use2050includesdecarbonisedincludeshaltingchangeelectricitysupplydeforestationb)GreenhousegasemissionsbysectoratthetimeofnetzeroCO2,comparedto201960KeyIllustrativeMitigationNon-CO2emissionsPathways(IMPs)GHGemissions40Transport,industryandbuildings(GtCO2-eq/yr)thesearedierentEnergysupply(includingelectricity)waystoachieveLand-usechangeandforestrynetzeroCO220SourcesPathwaysconsistentwithlimitingnetzero0warmingto1.5°Cor2°Cby2100Sinks2019IMP-GSGradualstrengtheningcomparisonIMP-NegHighrelianceonnetnegativeemissions−20IMP-GSHighrelianceonefﬁcientresourceuseIMP-NegIMP-LDFocusonsustainabledevelopmentIMP-SPFocusonrenewablesIMP-LDIMP-RenIMP-SPIMP-Renpathwaysto2°CalsoreachnetzeroCO2Highovershoot94Near-TermResponsesinaChangingClimateFigure4.1:Sectoralemissionsinpathwaysthatlimitwarmingto1.5°C.Panel(a)showssectoralCO2andnon-CO2emissionsinglobalmodelledpathwaysthatlimitwarmingto1.5°C(>50%)withnoorlimitedovershoot.Thehorizontallinesillustratehalving2015emissions(baseyearofthepathways)(dashed)andreachingnetzeroemissions(solidline).Therangeshowsthe5–95thpercentileoftheemissionsacrossthepathways.Thetimingstronglydiffersbysector,withtheCO2emissionsfromtheelectricity/fossilfuelindustriessectorandland-usechangegenerallyreachingnetzeroearlier.Non-CO2emissionsfromagriculturearealsosubstantiallyreducedcomparedtopathwayswithoutclimatepolicybutdonottypicallyreachzero.Panel(b)Althoughallpathwaysincludestronglyreducedemissions,therearedifferentpathwaysasindicatedbytheillustrativemitigationpathwaysusedinIPCCWGIII.Thepathwaysemphasiseroutesconsistentwithlimitingwarmingto1.5°Cwithahighrelianceonnetnegativeemissions(IMP-Neg),highresourceefﬁciency(IMP-LD),afocusonsustainabledevelopment(IMP-SP)orrenewables(IMP-Ren)andconsistentwith2°Cbasedonalessrapidintroductionofmitigationmeasuresfollowedbyasubsequentgradualstrengthening(IMP-GS).Positive(solidﬁlledbars)andnegativeemissions(hatchedbars)fordifferentillustrativemitigationpathwaysarecomparedtoGHGemissionsfromtheyear2019.Thecategory“energysupply(includingelectricity)”includesbioenergywithcarboncaptureandstorageanddirectaircarboncaptureandstorage.{WGIIIBoxTS.5,WGIII3.3,WGIII3.4,WGIII6.6,WGIII10.3,WGIII11.3}(Cross-SectionBox.2)4.2BeneﬁtsofStrengtheningNear-TermActionAcceleratedimplementationofadaptationwillimprovewell-beingbyreducinglossesanddamages,especiallyforvulnerablepopulations.Deep,rapid,andsustainedmitigationactionswouldreducefutureadaptationcostsandlossesanddamages,enhancesustainabledevelopmentco-beneﬁts,avoidlocking-inemissionsources,andreducestrandedassetsandirreversibleclimatechanges.Thesenear-termactionsinvolvehigherup-frontinvestmentsanddisruptivechanges,whichcanbemoderatedbyarangeofenablingconditionsandremovalorreductionofbarrierstofeasibility.(highconﬁdence)Acceleratedimplementationofadaptationresponseswillbringco-emittedbyGHGemittingsectorsandbecausemethaneemissionsSection4beneﬁtstohumanwell-being(highconﬁdence)(Section4.3).Asleadstosurfaceozoneformation(highconﬁdence).Thebeneﬁtsfromadaptationoptionsoftenhavelongimplementationtimes,long-termairqualityimprovementincludepreventionofairpollution-relatedplanningandacceleratedimplementation,particularlyinthisdecade,isprematuredeaths,chronicdiseasesanddamagestoecosystemsimportanttocloseadaptationgaps,recognisingthatconstraintsremainandcrops.Theeconomicbeneﬁtsforhumanhealthfromairqualityforsomeregions.Thebeneﬁtstovulnerablepopulationswouldbehighimprovementarisingfrommitigationactioncanbeofthesameorder(seeSection4.4).(highconﬁdence){WGISPMB.1,WGISPMB.1.3,WGIofmagnitudeasmitigationcosts,andpotentiallyevenlarger(mediumSPMB.2.2,WGISPMB.3;WGIISPMC.1.1,WGIISPMC.1.2,WGIISPMconﬁdence).AsmethanehasashortlifetimebutisapotentGHG,C.2,WGIISPMC.3.1,WGIIFigureSPM.4b;SROCCSPMC.3.4,SROCCstrong,rapidandsustainedreductionsinmethaneemissionscanlimitFigure3.4,SROCCFigureSPM.5}near-termwarmingandimproveairqualitybyreducingglobalsurfaceozone(highconﬁdence).{WGISPMD.1.7,WGISPMD.2.2,WGI6.7,Near-termactionsthatlimitglobalwarmingtocloseto1.5°CWGITSBoxTS.7,WGI6Box6.2,WGIFigure6.3,WGIFigure6.16,wouldsubstantiallyreduceprojectedlossesanddamagesrelatedWGIFigure6.17;WGIITS.D.8.3,WGIICross-ChapterBoxHEALTH,toclimatechangeinhumansystemsandecosystems,comparedWGII5ES,WGII7ES;WGII7.3.1.2;WGIIIFigureSPM.8,WGIIISPMtohigherwarminglevels,butcannoteliminatethemall(veryC.2.3,WGIIISPMC.4.2,WGIIITS.4.2}highconﬁdence).Themagnitudeandrateofclimatechangeandassociatedrisksdependstronglyonnear-termmitigationandadaptationChallengesfromdelayedadaptationandmitigationactionsactions,andprojectedadverseimpactsandrelatedlossesanddamagesincludetheriskofcostescalation,lock-inofinfrastructure,escalatewitheveryincrementofglobalwarming(veryhighconﬁdence).strandedassets,andreducedfeasibilityandeffectivenessDelayedmitigationactionwillfurtherincreaseglobalwarmingwhichofadaptationandmitigationoptions(highconﬁdence).Thewilldecreasetheeffectivenessofmanyadaptationoptions,includingcontinuedinstallationofunabatedfossilfuel148infrastructureEcosystem-basedAdaptationandmanywater-relatedoptions,aswellwill‘lock-in’GHGemissions(highconﬁdence).Limitingglobalasincreasingmitigationfeasibilityrisks,suchasforoptionsbasedonwarmingto2°Corbelowwillleaveasubstantialamountoffossilfuelsecosystems(highconﬁdence).Comprehensive,effective,andinnovativeunburnedandcouldstrandconsiderablefossilfuelinfrastructureresponsesintegratingadaptationandmitigationcanharnesssynergies(highconfidence),withgloballydiscountedvalueprojectedtobeandreducetrade-offsbetweenadaptationandmitigation,aswellasinaroundUSD1to4trillionfrom2015to2050(mediumconﬁdence).meetingrequirementsforﬁnancing(veryhighconﬁdence)(seeSectionEarlyactionswouldlimitthesizeofthesestrandedassets,whereas4.5,4.6,4.8and4.9).{WGIISPMB.3,WGIISPMB.4,WGIISPMB.6.2,delayedactionswithcontinuedinvestmentsinunabatedhigh-emittingWGIISPMC.2,WGIISPMC.3,WGIISPMD.1,WGIISPMD.4.3,WGIISPMD.5,infrastructureandlimiteddevelopmentanddeploymentoflow-emittingWGIITSD.1.4,WGIITS.D.5,WGIITSD.7.5;WGIIISPMB.6.3,WGIIISPMB.6.4,alternativespriorto2030wouldraisefuturestrandedassetstotheWGIIISPMC.9,WGIIISPMD.2,WGIIISPME.13;SR1.5SPMC.2.7,higherendoftherange–therebyactingasbarriersandincreasingSR1.5D.1.3,SR1.5D.5.2}politicaleconomyfeasibilityrisksthatmayjeopardiseeffortstolimitglobalwarming.(highconﬁdence).{WGIIISPMB.6.3,WGIIISPMC.4,MitigationactionswillhaveothersustainabledevelopmentWGIIIBoxTS.8}co-beneﬁts(highconﬁdence).Mitigationwillimproveairqualityandhumanhealthintheneartermnotablybecausemanyairpollutantsare148Inthiscontext,‘unabatedfossilfuels’referstofossilfuelsproducedandusedwithoutinterventionsthatsubstantiallyreducetheamountofGHGemittedthroughoutthelifecycle;forexample,capturing90%ormoreCO2frompowerplants,or50to80%offugitivemethaneemissionsfromenergysupply.{WGIIISPMfootnote54}95Section4Scaling-upnear-termclimateactions(Section4.1)willmobilisea(a)economy-widemainstreamingpackagessupportingoptionstomixoflow-costandhigh-costoptions.High-costoptions,asinenergyimprovedsustainablelow-emissioneconomicrecovery,developmentandinfrastructure,areneededtoavoidfuturelock-ins,fosterinnovationandjobcreationprograms(Sections4.4,4.5,4.6,4.8,4.9)(b)safetyandinitiatetransformationalchanges(Figure4.4).Climateresilientnetsandsocialprotectioninthetransition(Section4.4,4.7);anddevelopmentpathwaysinsupportofsustainabledevelopmentforallare(c)broadenedaccesstoﬁnance,technologyandcapacity-buildingshapedbyequity,andsocialandclimatejustice(veryhighconﬁdence).andcoordinatedsupporttolow-emissioninfrastructure(‘leap-frog’Embeddingeffectiveandequitableadaptationandmitigationinpotential),especiallyindevelopingregions,andunderdebtstressdevelopmentplanningcanreducevulnerability,conserveandrestore(highconﬁdence).(Section4.8){WGIISPMC.2,WGIISPMC.4.1,ecosystems,andenableclimateresilientdevelopment.ThisisespeciallyWGIISPMD.1.3,WGIISPMD.2,WGIISPMD.3.2,WGIISPME.2.2,challenginginlocalitieswithpersistentdevelopmentgapsandlimitedWGIISPME.4,WGIISPMTS.2,WGIISPMTS.5.2,WGIITS.6.4,resources.(highconﬁdence){WGIISPMC.5,WGIISPMD1;WGIIITS.5.2,WGIITS.15,WGIITSBoxTS.3;WGIIISPMB.4.2,WGIIISPMC.5.4,WGIII8.3.1,WGIII8.3.4,WGIII8.4.1,WGIII8.6}WGIIISPMC.6.2,WGIIISPMC.12.2,WGIIISPMD.3.4,WGIIISPME.4.2,WGIIISPME.4.5,WGIIISPME.5.2,WGIIISPME.5.3,WGIIITS.1,WGIIIBoxTS.15,Scaling-upclimateactionmaygeneratedisruptivechangesinWGIII15.2,WGIIICross-ChapterBox1onCOVIDinChapter1}economicstructurewithdistributionalconsequencesandneedtoreconciledivergentinterests,valuesandworldviews,withinandbetweencountries.Deeperﬁscal,ﬁnancial,institutionalandregulatoryreformscanoffsetsuchadverseeffectsandunlockmitigationpotentials.Societalchoicesandactionsimplementedinthisdecadewilldeterminetheextenttowhichmediumandlong-termdevelopmentpathwayswilldeliverhigherorlowerclimateresilientdevelopmentoutcomes.(highconﬁdence){WGIISPMD.2,WGIISPMD.5,WGIIBoxTS.8;WGIIISPMD.3,WGIIISPME.2,WGIIISPME.3,WGIIISPME.4,WGIIITS.2,WGIIITS.4.1,WGIIITS.6.4,WGIII15.2,WGIII15.6}SectioSnec4tion1Enablingconditionswouldneedtobestrengthenedinthenear-termandbarriersreducedorremovedtorealiseopportunitiesfordeepandrapidadaptationandmitigationactionsandclimateresilientdevelopment(highconﬁdence)(Figure4.2).Theseenablingconditionsaredifferentiatedbynational,regionalandlocalcircumstancesandgeographies,accordingtocapabilities,andinclude:equityandinclusioninclimateaction(seeSection4.4),rapidandfar-reachingtransitionsinsectorsandsystem(seeSection4.5),measurestoachievesynergiesandreducetrade-offswithsustainabledevelopmentgoals(seeSection4.6),governanceandpolicyimprovements(seeSection4.7),accesstofinance,improvedinternationalcooperationandtechnologyimprovements(seeSection4.8),andintegrationofnear-termactionsacrosssectors,systemsandregions(seeSection4.9).{WGIISPMD.2;WGIIISPME.1,WGIIISPME.2}Barrierstofeasibilitywouldneedtobereducedorremovedtodeploymitigationandadaptationoptionsatscale.Manylimitstofeasibilityandeffectivenessofresponsescanbeovercomebyaddressingarangeofbarriers,includingeconomic,technological,institutional,social,environmentalandgeophysicalbarriers.Thefeasibilityandeffectivenessofoptionsincreasewithintegrated,multi-sectoralsolutionsthatdifferentiateresponsesbasedonclimaterisk,cutacrosssystemsandaddresssocialinequities.Strengthenednear-termactionsinmodelledcost-effectivepathwaysthatlimitglobalwarmingto2°Corlower,reducetheoverallrisktothefeasibilityofthesystemtransitions,comparedtomodelledpathwayswithdelayedoruncoordinatedaction.(highconﬁdence){WGIISPMC.2,WGIISPMC.3,WGIISPMC.5;WGIIISPME.1,WGIIISPME.1.3}Integratingambitiousclimateactionswithmacroeconomicpoliciesunderglobaluncertaintywouldprovidebenefits(highconfidence).Thisencompassesthreemaindirections:96Near-TermResponsesinaChangingClimateThereisarapidlynarrowingwindowofopportunitytoenableclimateresilientdevelopmentMultipleinteractingchoicesandactionscanshiftdevelopmentpathwaystowardssustainabilityConditionsthatenableSustainableDevelopmentOutcomescharacterisingGoal(SDG)achievementdevelopmentpathwaysindividualandcollectiveactionsEarlyactionandenablingmissed1.5°CLowemissions•InclusivegovernanceconditionscreatefuturenitiestobelowSystemtransitions•Diverseknowledgesandvaluesopportunitiesforclimateopportulimited•FinanceandinnovationresilientdevelopmentwarmingTransformation•IntegrationacrosssectorsLowclimateriskEmissionsreductionsEquityandjusticeandtimescalesAdaptationSDGachievement•Ecosystemstewardship•SynergiesbetweenclimateSustainableDevelopmentClimateResilientDevelopmentanddevelopmentactions•Behaviouralchangesupportedbypolicy,infrastructureandsocio-culturalfactorsGovernmentsCivilPrivatePastconditionsHighemissionssocietysector(emissions,climateEntrenchedsystemschange,development)AdaptationlimitsConditionsthatconstrainhaveincreasedwarminganddevelopmentgapspersistMaladaptationindividualandcollectiveactionsIncreasingclimateriskProspectsforclimate•Poverty,inequityandinjusticePastPresentresilientdevelopmentwill2100Reducedoptions•Economic,institutional,socialconditionsworldbefurtherlimitedifglobal&beyondfordevelopmentIPCCAR6warmingexceeds1.5°CandandcapacitybarriersifprogresstowardstheSDGsEcosystem•Siloedresponsesisinadequatedegradation•Lackofﬁnance,andbarriers2030Illustrative‘shock’thattoﬁnanceandtechnologydisruptsdevelopment•TradeoffswithSDGsFigure4.2:Theillustrativedevelopmentpathways(redtogreen)andassociatedoutcomes(rightpanel)showthatthereisarapidlynarrowingwindowofSection4opportunitytosecurealiveableandsustainablefutureforall.Climateresilientdevelopmentistheprocessofimplementinggreenhousegasmitigationandadaptationmeasurestosupportsustainabledevelopment.Divergingpathwaysillustratethatinteractingchoicesandactionsmadebydiversegovernment,privatesectorandcivilsocietyactorscanadvanceclimateresilientdevelopment,shiftpathwaystowardssustainability,andenableloweremissionsandadaptation.Diverseknowledgesandvaluesincludeculturalvalues,IndigenousKnowledge,localknowledge,andscientiﬁcknowledge.Climaticandnon-climaticevents,suchasdroughts,ﬂoodsorpandemics,posemoresevereshockstopathwayswithlowerclimateresilientdevelopment(redtoyellow)thantopathwayswithhigherclimateresilientdevelopment(green).Therearelimitstoadaptationandadaptivecapacityforsomehumanandnaturalsystemsatglobalwarmingof1.5°C,andwitheveryincrementofwarming,lossesanddamageswillincrease.ThedevelopmentpathwaystakenbycountriesatallstagesofeconomicdevelopmentimpactGHGemissionsandhenceshapemitigationchallengesandopportunities,whichvaryacrosscountriesandregions.Pathwaysandopportunitiesforactionareshapedbypreviousactions(orinactionsandopportunitiesmissed,dashedpathway),andenablingandconstrainingconditions(leftpanel),andtakeplaceinthecontextofclimaterisks,adaptationlimitsanddevelopmentgaps.Thelongeremissionsreductionsaredelayed,thefewereffectiveadaptationoptions.{WGISPMB.1;WGIISPMB.1toB.5,WGIISPMC.2to5,WGIISPMD.1to5,WGIIFigureSPM.3,WGIIFigureSPM.4,WGIIFigureSPM.5,WGIITS.D.5,WGII3.1,WGII3.2,WGII3.4,WGII4.2,WGIIFigure4.4,WGII4.5,WGII4.6,WGII4.9;WGIIISPMA,WGIIISPMB1,WGIIISPMB.3,WGIIISPMB.6,WGIIISPMC.4,WGIIISPMD1to3,WGIIISPME.1,WGIIISPME.2,WGIIISPME.4,WGIIISPME.5,WGIIIFigureTS.1,WGIIIFigureTS.7,WGIIIBoxTS.3,WGIIIBoxTS.8,Cross-WorkingGroupBox1inChapter3,WGIIICross-ChapterBox5inChapter4;SR1.5SPMD.1to6;SRCCLSPMD.3}4.3Near-TermRisksManychangesintheclimatesystem,includingextremeevents,willbecomelargerintheneartermwithincreasingglobalwarming(highconﬁdence).Multipleclimaticandnon-climaticriskswillinteract,resultinginincreasedcompoundingandcascadingimpactsbecomingmoredifﬁculttomanage(highconﬁdence).Lossesanddamageswillincreasewithincreasingglobalwarming(veryhighconﬁdence),whilestronglyconcentratedamongthepoorestvulnerablepopulations(highconﬁdence).Continuingwithcurrentunsustainabledevelopmentpatternswouldincreaseexposureandvulnerabilityofecosystemsandpeopletoclimatehazards(highconﬁdence).97Section4SectioSnec4tion1Globalwarmingwillcontinuetoincreaseinthenearterm(2021–2040)land,ocean,andwater(highconﬁdence).Severalnear-termriskscanmainlyduetoincreasedcumulativeCO2emissionsinnearlyallbemoderatedwithadaptation(highconﬁdence).{WGISPMC.2.6;consideredscenariosandpathways.Inthenearterm,everyWGIISPMB.2,WGIISPMB.2.3,WGIISPMB.2.5,WGIISPMB.3,regionintheworldisprojectedtofacefurtherincreasesinWGIISPMB.3.2,WGIITS.C.5.2}(Section4.5and3.2)climatehazards(mediumtohighconﬁdence,dependingonregionandhazard),increasingmultipleriskstoecosystemsPrincipalhazardsandassociatedrisksexpectedintheneartermandhumans(veryhighconﬁdence).Inthenearterm,natural(at1.5°Cglobalwarming)are:variability149willmodulatehuman-causedchanges,eitherattenuatingoramplifyingprojectedchanges,especiallyatregionalscales,withlittle•Increasedintensityandfrequencyofhotextremesanddangerouseffectoncentennialglobalwarming.Thosemodulationsareimportantheat-humidityconditions,withincreasedhumanmortality,morbidity,toconsiderinadaptationplanning.Globalsurfacetemperatureinanyandlabourproductivityloss(highconﬁdence).{WGISPMB.2.2,singleyearcanvaryaboveorbelowthelong-termhuman-inducedWGITSFigureTS.6;WGIISPMB.1.4,WGIISPMB.4.4,trend,duetonaturalvariability.By2030,globalsurfacetemperatureWGIIFigureSPM.2}inanyindividualyearcouldexceed1.5°Crelativeto1850–1900withaprobabilitybetween40%and60%,acrossthefivescenariosassessed•IncreasingfrequencyofmarineheatwaveswillincreaserisksinWGI(mediumconfidence).Theoccurrenceofindividualyearswithofbiodiversitylossintheoceans,includingfrommassmortalityglobalsurfacetemperaturechangeaboveacertainleveldoesnotevents(highconﬁdence).{WGISPMB.2.3;WGIISPMB.1.2,implythatthisglobalwarminglevelhasbeenreached.IfalargeWGIIFigureSPM.2;SROCCSPMB.5.1}explosivevolcaniceruptionweretooccurinthenearterm150,itwouldtemporarilyandpartiallymaskhuman-causedclimatechange•Near-termrisksforbiodiversitylossaremoderatetohighinbyreducingglobalsurfacetemperatureandprecipitation,especiallyforestecosystems(mediumconﬁdence)andkelpandseagrassoverland,foronetothreeyears(mediumconﬁdence).{WGISPMB.1.3,ecosystems(hightoveryhighconﬁdence)andarehightoveryWGISPMB.1.4,WGISPMC.1,WGISPMC.2,WGICross-SectionBoxTS.1,highinArcticsea-iceandterrestrialecosystems(highconﬁdence)WGICross-ChapterBox4.1;WGIISPMB.3,WGIISPMB.3.1;andwarm-watercoralreefs(veryhighconﬁdence).{WGIISPMB.3.1}WGIIIBoxSPM.1Figure1}•MoreintenseandfrequentextremerainfallandassociatedﬂoodingThelevelofriskforhumansandecosystemswilldependonnear-terminmanyregionsincludingcoastalandotherlow-lyingcitiestrendsinvulnerability,exposure,levelofsocio-economic(mediumtohighconﬁdence),andincreasedproportionofanddevelopmentandadaptation(highconﬁdence).Inthenearterm,peakwindspeedsofintensetropicalcyclones(highconﬁdence).manyclimate-associatedriskstonaturalandhumansystemsdepend{WGISPMB.2.4,WGISPMC.2.2,WGISPMC.2.6,WGI11.7}morestronglyonchangesinthesesystems’vulnerabilityandexposurethanondifferencesinclimatehazardsbetweenemissionsscenarios•Highrisksfromdrylandwaterscarcity,wildﬁredamage,and(highconﬁdence).Futureexposuretoclimatichazardsisincreasingpermafrostdegradation(mediumconﬁdence).{SRCCLSPMA.5.3.}globallyduetosocio-economicdevelopmenttrendsincludinggrowinginequality,andwhenurbanisationormigrationincreaseexposure•Continuedsealevelriseandincreasedfrequencyand(highconﬁdence).Urbanisationincreaseshotextremes(veryhighmagnitudeofextremesealeveleventsencroachingoncoastalconﬁdence)andprecipitationrunoffintensity(highconﬁdence).humansettlementsanddamagingcoastalinfrastructure(highIncreasingurbanisationinlow-lyingandcoastalzoneswillbeamajorconﬁdence),committinglow-lyingcoastalecosystemstodriverofincreasingexposuretoextremeriverﬂoweventsandsealevelsubmergenceandloss(mediumconﬁdence),expandinglandrisehazards,increasingrisks(highconﬁdence)(Figure4.3).Vulnerabilitysalinization(veryhighconﬁdence),withcascadingtoriskstowillalsoriserapidlyinlow-lyingSmallIslandDevelopingStatesandlivelihoods,health,well-being,culturalvalues,foodandwateratollsinthecontextofsealevelrise(highconﬁdence)(seeFigure3.4andsecurity(highconﬁdence).{WGISPMC.2.5,WGISPMC.2.6;Figure4.3).HumanvulnerabilitywillconcentrateininformalsettlementsWGIISPMB.3.1,WGIISPMB.5.2;SRCCLSPMA.5.6;SROCCSPMB.3.4,andrapidlygrowingsmallersettlements;andvulnerabilityinruralSROCCSPM3.6,SROCCSPMB.9.1}(Figure3.4,4.3)areaswillbeheightenedbyreducedhabitabilityandhighrelianceonclimate-sensitivelivelihoods(highconﬁdence).Humanandecosystem•Climatechangewillsigniﬁcantlyincreaseillhealthandprematurevulnerabilityareinterdependent(highconﬁdence).Vulnerabilitytodeathsfromtheneartolongterm(highconﬁdence).Furtherclimatechangeforecosystemswillbestronglyinﬂuencedbypast,warmingwillincreaseclimate-sensitivefood-borne,water-borne,present,andfuturepatternsofhumandevelopment,includingfromandvector-bornediseaserisks(highconﬁdence),andmentalhealthunsustainableconsumptionandproduction,increasingdemographicchallengesincludinganxietyandstress(veryhighconﬁdence).pressures,andpersistentunsustainableuseandmanagementof{WGIISPMB.4.4}149SeeAnnexI:Glossary.ThemaininternalvariabilityphenomenaincludeElNiño–SouthernOscillation,PaciﬁcDecadalVariabilityandAtlanticMulti-decadalVariabilitythroughtheirregionalinfluence.Theinternalvariabilityofglobalsurfacetemperatureinanysingleyearisestimatedtobeabout±0.25°C(5to95%range,highconfidence).{WGISPMfootnote29,WGISPMfootnote37}150Basedon2500-yearreconstructions,eruptionswitharadiativeforcingmorenegativethan–1Wm-2,relatedtotheradiativeeffectofvolcanicstratosphericaerosolsintheliteratureassessedinthisreport,occuronaveragetwicepercentury.{WGISPMfootnote38}98•Cryosphere-relatedchangesinﬂoods,landslides,andwaterNear-TermResponsesinaChangingClimateSection4availabilityhavethepotentialtoleadtosevereconsequencesforpeople,infrastructureandtheeconomyinmostmountainregions99(highconﬁdence).{WGIITSC.4.2}•Theprojectedincreaseinfrequencyandintensityofheavyprecipitation(highconﬁdence)willincreaserain-generatedlocalﬂooding(mediumconﬁdence).{WGIFigureSPM.6,WGISPMB.2.2;WGIITSC.4.5}Multipleclimatechangeriskswillincreasinglycompoundandcascadeinthenearterm(highconﬁdence).Manyregionsareprojectedtoexperienceanincreaseintheprobabilityofcompoundeventswithhigherglobalwarming(highconﬁdence)includingconcurrentheatwavesanddrought.Riskstohealthandfoodproductionwillbemademoreseverefromtheinteractionofsuddenfoodproductionlossesfromheatanddrought,exacerbatedbyheat-inducedlabourproductivitylosses(highconﬁdence)(Figure4.3).Theseinteractingimpactswillincreasefoodprices,reducehouseholdincomes,andleadtohealthrisksofmalnutritionandclimate-relatedmortalitywithnoorlowlevelsofadaptation,especiallyintropicalregions(highconﬁdence).Concurrentandcascadingrisksfromclimatechangetofoodsystems,humansettlements,infrastructureandhealthwillmaketheserisksmoresevereandmoredifﬁculttomanage,includingwheninteractingwithnon-climaticriskdriverssuchascompetitionforlandbetweenurbanexpansionandfoodproduction,andpandemics(highconﬁdence).Lossofecosystemsandtheirserviceshascascadingandlong-termimpactsonpeopleglobally,especiallyforIndigenousPeoplesandlocalcommunitieswhoaredirectlydependentonecosystems,tomeetbasicneeds(highconﬁdence).Increasingtransboundaryrisksareprojectedacrossthefood,energyandwatersectorsasimpactsfromweatherandclimateextremespropagatethroughsupply-chains,markets,andnaturalresourceﬂows(highconﬁdence)andmayinteractwithimpactsfromothercrisessuchaspandemics.Risksalsoarisefromsomeresponsesintendedtoreducetherisksofclimatechange,includingrisksfrommaladaptationandadversesideeffectsofsomeemissionsreductionandcarbondioxideremovalmeasures,suchasafforestationofnaturallyunforestedlandorpoorlyimplementedbioenergycompoundingclimate-relatedriskstobiodiversity,foodandwatersecurity,andlivelihoods(highconﬁdence)(seeSection3.4.1and4.5).{WGISPM.2.7;WGIISPMB.2.1,WGIISPMB.5,WGIISPMB.5.1,WGIISPMB.5.2,WGIISPMB.5.3,WGIISPMB.5.4,WGIICross-ChapterBoxCOVIDinChapter7;WGIIISPMC.11.2;SRCCLSPMA.5,SRCCLSPMA.6.5}(Figure4.3)Witheveryincrementofglobalwarminglossesanddamageswillincrease(veryhighconﬁdence),becomeincreasinglydifﬁculttoavoidandbestronglyconcentratedamongthepoorestvulnerablepopulations(highconﬁdence).Adaptationdoesnotpreventalllossesanddamages,evenwitheffectiveadaptationandbeforereachingsoftandhardlimits.Lossesanddamageswillbeunequallydistributedacrosssystems,regionsandsectorsandarenotcomprehensivelyaddressedbycurrentﬁnancial,governanceandinstitutionalarrangements,particularlyinvulnerabledevelopingcountries.(highconﬁdence).{WGIISPMB.4,WGIISPMC.3,WGIISPMC.3.5}Section4Everyregionfacesmoresevereand/orfrequentcompoundandcascadingclimaterisksa)Increaseinthepopulationexposedtosealevelrisefrom2020to2040Exposuretoacoastalﬂoodingeventthatcurrentlyoccursonaverageonceevery100yearsEurope0.67millionNorthAmerica+0.38million(57%)0.34millionabsoluteincreaseAsia(andpercentincrease)63.81million+0.24million(71%)+16.36million(26%)CentralandAfricaSouthAmerica2.40million0.69million+2.29million(95%)+0.24million(35%)SmallIslandsPopulationexposedin2020Australasia0.18millionAdditionalpopulationexposedin2040SSP2-4.50.02million+0.10million(57%)Increaseduetosealevelriseonly+0.01million(52%)Increaseduetosealevelriseandpopulationchange0.11millionmillionb)Increasedfrequencyofextremesealeveleventsby2040Frequencyofeventsthatcurrentlyoccuronaverageonceevery100yearsTheabsenceofacircleindicatesaninabilitytoperformanassessmentduetoalackofdata.SectioSnec4tion1ProjectedchangetoAnnualevent1-in-100yeareventsDecadaleventundertheintermediateTwice-a-centuryeventSSP2-4.5scenarioNochangec)Exampleofcomplexrisk,whereimpactsfromclimateextremeeventshavecascadingeffectsonfood,nutrition,livelihoodsandwell-beingofsmallholderfarmersMultipleclimatechangerisksMorefrequentandmoreintensewillincreasinglycompoundandcascadeintheneartermExtremeheatanddroughtReducedhouseholdReducedsoilmoistureFoodpricesincomeandhealthincreaseKeyReducedlabourFoodyieldReducedBi-directionalcapacityandqualitylossesfoodsecuritycompoundingUni-directionalDecreasedIncreasedmalnutritioncompoundingordominoqualityoflifeContagioneffecton(particularlymaternalmalnutritionmultiplerisksandchildundernutrition)100Near-TermResponsesinaChangingClimateFigure4.3:Everyregionfacesmoresevereorfrequentcompoundand/orcascadingclimaterisksinthenearterm.Changesinriskresultfromchangesinthedegreeofthehazard,thepopulationexposed,andthedegreeofvulnerabilityofpeople,assets,orecosystems.Panel(a)Coastalﬂoodingeventsaffectmanyofthehighlypopulatedregionsoftheworldwherelargepercentagesofthepopulationareexposed.Thepanelshowsnear-termprojectedincreaseofpopulationexposedto100-yearﬂoodingeventsdepictedastheincreasefromtheyear2020to2040(duetosealevelriseandpopulationchange),basedontheintermediateGHGemissionsscenario(SSP2-4.5)andcurrentadaptationmeasures.Out-migrationfromcoastalareasduetofuturesealevelriseisnotconsideredinthescenario.Panel(b)projectedmedianprobabilityintheyear2040forextremewaterlevelsresultingfromacombinationofmeansealevelrise,tidesandstormsurges,whichhaveahistorical1%averageannualprobability.Apeak-over-threshold(99.7%)methodwasappliedtothehistoricaltidegaugeobservationsavailableintheGlobalExtremeSeaLevelAnalysisversion2database,whichisthesameinformationasWGIFigure9.32,exceptherethepanelusesrelativesealevelprojectionsunderSSP2-4.5fortheyear2040insteadof2050Theabsenceofacircleindicatesaninabilitytoperformanassessmentduetoalackofdata,butdoesnotindicateabsenceofincreasingfrequencies.Panel(c)Climatehazardscaninitiateriskcascadesthataffectmultiplesectorsandpropagateacrossregionsfollowingcomplexnaturalandsocietalconnections.Thisexampleofacompoundheatwaveandadroughteventstrikinganagriculturalregionshowshowmultiplerisksareinterconnectedandleadtocascadingbiophysical,economic,andsocietalimpactsevenindistantregions,withvulnerablegroupssuchassmallholderfarmers,childrenandpregnantwomenparticularlyimpacted.{WGIFigure9.32;WGIISPMB4.3,WGIISPMB1.3,WGIISPMB.5.1,WGIITSFigureTS.9,WGIITSFigureTS.10(c),WGIIFig5.2,WGIITS.B.2.3,WGIITS.B.2.3,WGIITS.B.3.3,WGII9.11.1.2}4.4EquityandInclusioninClimateChangeActionActionsthatprioritiseequity,climatejustice,socialjusticeandinclusionleadtomoresustainableoutcomes,co-beneﬁts,reducetrade-offs,supporttransformativechangeandadvanceclimateresilientdevelopment.Adaptationresponsesareimmediatelyneededtoreducerisingclimaterisks,especiallyforthemostvulnerable.Equity,inclusionandjusttransitionsarekeytoprogressonadaptationanddeepersocietalambitionsforacceleratedmitigation.(highconﬁdence)Adaptationandmitigationactions,acrossscales,sectorsandvulnerabilityareinﬂuencedbyhistoricalandongoingpatternsofSection4regions,thatprioritiseequity,climatejustice,rights-basedinequitysuchascolonialism,especiallyformanyIndigenousPeoplesapproaches,socialjusticeandinclusivity,leadtomoreandlocalcommunities(highconﬁdence).Vulnerabilityisexacerbatedsustainableoutcomes,reducetrade-offs,supporttransformativebyinequityandmarginalisationlinkedtogender,ethnicity,lowincomechangeandadvanceclimateresilientdevelopment(highorcombinationsthereof,especiallyformanyIndigenousPeoplesandconﬁdence).Redistributivepoliciesacrosssectorsandregionsthatlocalcommunities(highconﬁdence).{WGIISPMB.2,WGIISPMB.2.4,shieldthepoorandvulnerable,socialsafetynets,equity,inclusionWGIISPMB.3.2,WGIISPMB.3.3,WGIISPMC.1,WGIISPMC.1.2,andjusttransitions,atallscalescanenabledeepersocietalambitionsWGIISPMC.2.9}andresolvetrade-offswithsustainabledevelopmentgoals.(SDGs),particularlyeducation,hunger,poverty,genderandenergyaccess(highMeaningfulparticipationandinclusiveplanning,informedbyconﬁdence).Mitigationeffortsembeddedwithinthewiderdevelopmentculturalvalues,IndigenousKnowledge,localknowledge,andcontextcanincreasethepace,depthandbreadthofemissionreductionsscientiﬁcknowledgecanhelpaddressadaptationgapsand(mediumconﬁdence).Equity,inclusionandjusttransitionsatallavoidmaladaptation(highconﬁdence).Suchactionswithﬂexiblescalesenabledeepersocietalambitionsforacceleratedmitigation,pathwaysmayencouragelow-regretandtimelyactions(veryhighandclimateactionmorebroadly(highconﬁdence).Thecomplexityinconﬁdence).Integratingclimateadaptationintosocialprotectionriskofrisingfoodprices,reducedhouseholdincomes,andhealthandprogrammes,includingcashtransfersandpublicworksprogrammes,climate-relatedmalnutrition(particularlymaternalmalnutritionandwouldincreaseresiliencetoclimatechange,especiallywhensupportedchildundernutrition)andmortalityincreaseswithlittleorlowlevelsbybasicservicesandinfrastructure(highconﬁdence).{WGIISPMC.2.3,ofadaptation(highconﬁdence).{WGIISPMB.5.1,WGIISPMC.2.9,WGIISPMC.4.3,WGIISPMC.4.4,WGIISPMC.2.9,WGIIWPMD.3}WGIISPMD.2.1,WGIITSBoxTS.4;WGIIISPMD.3,WGIIISPMD.3.3,WGIIISPMWGIIISPME.3,SR1.5SPMD.4.5}(Figure4.3c)Equity,inclusion,justtransitions,broadandmeaningfulparticipationofallrelevantactorsindecisionmakingatRegionsandpeoplewithconsiderabledevelopmentconstraintsallscalesenabledeepersocietalambitionsforacceleratedhavehighvulnerabilitytoclimatichazards.Adaptationmitigation,andclimateactionmorebroadly,andbuildsocialoutcomesforthemostvulnerablewithinandacrosscountriestrust,supporttransformativechangesandanequitablesharingandregionsareenhancedthroughapproachesfocusingonofbeneﬁtsandburdens(highconﬁdence).Equityremainsaequity,inclusivity,andrights-basedapproaches,including3.3tocentralelementintheUNclimateregime,notwithstandingshifts3.6billionpeoplelivingincontextsthatarehighlyvulnerableindifferentiationbetweenstatesovertimeandchallengesintoclimatechange(highconﬁdence).Vulnerabilityishigherinassessingfairshares.Ambitiousmitigationpathwaysimplylargeandlocationswithpoverty,governancechallengesandlimitedaccesssometimesdisruptivechangesineconomicstructure,withsigniﬁcanttobasicservicesandresources,violentconﬂictandhighlevelsofdistributionalconsequences,withinandbetweencountries,includingclimate-sensitivelivelihoods(e.g.,smallholderfarmers,pastoralists,shiftingofincomeandemploymentduringthetransitionfromhightoﬁshingcommunities)(highconﬁdence).Severalriskscanbemoderatedlowemissionsactivities(highconﬁdence).Whilesomejobsmaybelost,withadaptation(highconﬁdence).Thelargestadaptationgapslow-emissionsdevelopmentcanalsoopenupopportunitiestoenhanceexistamonglowerincomepopulationgroups(highconﬁdence)andskillsandcreatejobs(highconﬁdence).Broadeningequitableaccessadaptationprogressisunevenlydistributedwithobservedadaptationtoﬁnance,technologiesandgovernancethatfacilitatemitigation,andgaps(highconﬁdence).Presentdevelopmentchallengescausinghighconsiderationofclimatejusticecanhelpequitablesharingofbeneﬁts101Section4andburdens,especiallyforvulnerablecountriesandcommunities.citizens,investors,consumers,rolemodels,andprofessionals(high{WGIIISPMD.3,WGIIISPMD.3.2,WGIIISPMD.3.3,WGIIISPMD.3.4,conﬁdence).Thereareoptionsondesignofinstrumentssuchastaxes,WGIIITSBoxTS.4}subsidies,prices,andconsumption-basedapproaches,complementedbyregulatoryinstrumentstoreducehigh-emissionsconsumptionwhileDevelopmentprioritiesamongcountriesalsoreﬂectdifferentimprovingequityandsocietalwell-being(highconﬁdence).Behaviourstartingpointsandcontexts,andenablingconditionsforandlifestylechangestohelpend-usersadoptlow-GHG-intensiveshiftingdevelopmentpathwaystowardsincreasedsustainabilityoptionscanbesupportedbypolicies,infrastructureandtechnologywillthereforediffer,givingrisetodifferentneeds(highwithmultipleco-beneﬁtsforsocietalwell-being(highconﬁdence).conﬁdence).ImplementingjusttransitionprinciplesthroughcollectiveBroadeningequitableaccesstodomesticandinternationalﬁnance,andparticipatorydecision-makingprocessesisaneffectivewayoftechnologiesandcapacitycanalsoactasacatalystforacceleratingintegratingequityprinciplesintopoliciesatallscalesdependingmitigationandshiftingdevelopmentpathwaysinlow-incomecontextsonnationalcircumstances,whileinseveralcountriesjusttransition(highconﬁdence).Eradicatingextremepoverty,energypoverty,andcommissions,taskforcesandnationalpolicieshavebeenestablishedprovidingdecentlivingstandardstoallintheseregionsinthecontextof(mediumconﬁdence).{WGIIISPMD.3.1,WGIIISPMD.3.3}achievingsustainabledevelopmentobjectives,inthenearterm,canbeachievedwithoutsigniﬁcantglobalemissionsgrowth(highconﬁdence).ManyeconomicandregulatoryinstrumentshavebeenTechnologydevelopment,transfer,capacitybuildingandﬁnancingcaneffectiveinreducingemissionsandpracticalexperiencehassupportdevelopingcountries/regionsleapfroggingortransitioningtoinformedinstrumentdesigntoimprovethemwhileaddressinglow-emissionstransportsystemstherebyprovidingmultipleco-beneﬁtsdistributionalgoalsandsocialacceptance(highconﬁdence).The(highconﬁdence).Climateresilientdevelopmentisadvancedwhendesignofbehaviouralinterventions,includingthewaythatchoicesareactorsworkinequitable,justandenablingwaystoreconciledivergentpresentedtoconsumersworksynergisticallywithpricesignals,makinginterests,valuesandworldviews,towardequitableandjustoutcomesthecombinationmoreeffective(mediumconﬁdence).Individualswith(highconﬁdence).{WGIID.2.1,WGIIISPMB.3.3,WGIIISPM.C.8.5,WGIIIhighsocio-economicstatuscontributedisproportionatelytoemissions,SPMC.10.2,WGIIISPMC.10.4,WGIIISPMD.3.4,WGIIISPME.4.2,andhavethehighestpotentialforemissionsreductions,e.g.,asWGIIITS.5.1,WGIII5.4,WGIII5.8,WGIII15.2}SectioSnec4tion14.5Near-TermMitigationandAdaptationActionsRapidandfar-reachingtransitionsacrossallsectorsandsystemsarenecessarytoachievedeepandsustainedemissionsreductionsandsecurealiveableandsustainablefutureforall.Thesesystemtransitionsinvolveasigniﬁcantupscalingofawideportfolioofmitigationandadaptationoptions.Feasible,effectiveandlow-costoptionsformitigationandadaptationarealreadyavailable,withdifferencesacrosssystemsandregions.(highconﬁdence)Rapidandfar-reachingtransitionsacrossallsectorsandsystemsglobalGHGemissionsbyatleasthalfthe2019levelby2030(optionsarenecessarytoachievedeepemissionsreductionsandsecurecostinglessthanUSD20tCO2-eq–1areestimatedtomakeupmorealiveableandsustainablefutureforall(highconﬁdence).Systemthanhalfofthispotential)(highconﬁdence)(Figure4.4).Thetransitions151consistentwithpathwaysthatlimitwarmingto1.5°Cavailability,feasibility152andpotentialofmitigationoreffectiveness(>50%)withnoorlimitedovershootaremorerapidandpronouncedofadaptationoptionsintheneartermdifferacrosssystemsandinthenear-termthaninthosethatlimitwarmingto2°C(>67%)regions(veryhighconfidence).{WGIISPMC.2;WGIIISPMC.12,(highconﬁdence).SuchasystemicchangeisunprecedentedintermsWGIIISPME.1.1;SR1.5SPMB.6}ofscale,butnotnecessarilyintermsofspeed(mediumconﬁdence).ThesystemtransitionsmakepossiblethetransformativeadaptationDemand-sidemeasuresandnewwaysofend-useservicerequiredforhighlevelsofhumanhealthandwell-being,economicandprovisioncanreduceglobalGHGemissionsinend-usesectorsbysocialresilience,ecosystemhealth,andplanetaryhealth.{WGIISPM40to70%by2050comparedtobaselinescenarios,whilesomeA,WGIIFigureSPM.1;WGIIISPMC.3;SR1.5SPMC.2,SR1.5SPMregionsandsocioeconomicgroupsrequireadditionalenergyC.2.1,SR1.5SPMC.2,SR1.5SPMC.5}andresources.Demand-sidemitigationencompasseschangesininfrastructureuse,end-usetechnologyadoption,andsocio-culturalandFeasible,effectiveandlow-costoptionsformitigationandbehaviouralchange.(highconﬁdence)(Figure4.4).{WGIIISPMC.10}adaptationarealreadyavailable(highconﬁdence)(Figure4.4).MitigationoptionscostingUSD100tCO2-eq–1orlesscouldreduce151Systemtransitionsinvolveawideportfolioofmitigationandadaptationoptionsthatenabledeepemissionsreductionsandtransformativeadaptationinallsectors.Thisreporthasaparticularfocusonthefollowingsystemtransitions:energy;industry;cities,settlementsandinfrastructure;land,ocean,foodandwater;healthandnutrition;andsociety,livelihoodandeconomies.{WGIISPMA,WGIIFigureSPM.1,WGIIFigureSPM.4;SR1.5SPMC.2}152SeeAnnexI:Glossary.102Near-TermResponsesinaChangingClimateTherearemultipleopportunitiesforscalingupclimateactiona)Feasibilityofclimateresponsesandadaptation,andpotentialofmitigationoptionsintheneartermClimateresponsesandPotentialMitigationoptionsoptionscosting100USDtCO2-eq-1oradaptationoptionsfeasibilitylesscouldreduceglobalemissionsbyupto1.5°Catleasthalfofthe2019levelby2030SynergieswithPotentialcontributiontoGtCO2-eq/yrmitigationnetemissionreduction,2030012345ENERGYSUPPLYSolarEnergyreliability(e.g.Winddiversiﬁcation,access,stability)Reducemethanefromcoal,oilandgasResilientpowersystemsBioelectricity(includesBECCS)GeothermalandhydropowerImprovewateruseefﬁciencyNuclearFossilCarbonCaptureandStorage(CCS)LAND,WATER,FOODEfﬁcientlivestocksystemsReduceconversionofnaturalecosystemsImprovedcroplandmanagementCarbonsequestrationinagricultureEcosystemrestoration,Wateruseefﬁciencyandwaterafforestation,reforestationresourcemanagementShifttosustainablehealthydietsBiodiversitymanagementandImprovedsustainableforestmanagementecosystemconnectivityReducemethaneandN2OinagricultureAgroforestryReducefoodlossandfoodwasteSustainableaquacultureandﬁsheriesForest-basedadaptationnotassessedIntegratedcoastalzonemanagementSOCIETY,LIVELIHOODHEALTHSETTLEMENTSANDINFRASTRUCTURECoastaldefenceandhardeningEfﬁcientbuildingsSection4SustainableurbanwatermanagementFuelefﬁcientvehiclesSustainablelanduseandurbanplanningElectricvehiclesGreeninfrastructureandEfﬁcientlighting,appliancesecosystemservicesandequipmentEnhancedhealthservicesPublictransportandbicycling(e.g.WASH,nutritionanddiets)BiofuelsfortransportEfﬁcientshippingandaviationAvoiddemandforenergyservicesOnsiterenewablesANDECONOMYRiskspreadingandsharingINDUSTRYANDWASTEFuelswitchingSocialsafetynetsReduceemissionofﬂuorinatedgasClimateservices,includingEnergyefﬁciencyEarlyWarningSystemsMaterialefﬁciencyDisasterriskmanagementReducemethanefromwaste/wastewaterHumanmigrationConstructionmaterialssubstitutionPlannedrelocationandresettlementEnhancedrecyclingLivelihooddiversiﬁcationCarboncapturewithutilisation(CCU)andCCSFeasibilitylevelandsynergiesConﬁdencelevelinpotentialfeasibilityNetlifetimecostofoptions:50–100(USDpertCO2-eq)withmitigationandinsynergieswithmitigation100–200(USDpertCO2-eq)CostsarelowerthanthereferenceCostnotallocatedduetohighHighMediumLowHighMediumLow0–20(USDpertCO2-eq)variabilityorlackofdata20–50(USDpertCO2-eq)Insufﬁcientevidenceb)Potentialofdemand-side010GtCO2-eq/yr20mitigationoptionsby2050Food10GtCO2/yr44%therangeofGHGemissions0reductionpotentialis40-70%Landtransport67%20intheseend-usesectors66%BuildingsKeyTotalemissions(2050)Industry29%%PercentageofpossiblereductionElectricityAdditionalelectriﬁcation(+60%)Demand-sidemitigationpotential73%reduction(beforePotentialrangeadditionalelectriﬁcation)103Section4Figure4.4:MultipleOpportunitiesforscalingupclimateaction.Panel(a)presentsselectedmitigationandadaptationoptionsacrossdifferentsystems.Thelefthandsideofpanel(a)showsclimateresponsesandadaptationoptionsassessedfortheirmultidimensionalfeasibilityatglobalscale,intheneartermandupto1.5°Cglobalwarming.Asliteratureabove1.5°Cislimited,feasibilityathigherlevelsofwarmingmaychange,whichiscurrentlynotpossibletoassessrobustly.Thetermresponseisusedhereinadditiontoadaptationbecausesomeresponses,suchasmigration,relocationandresettlementmayormaynotbeconsideredtobeadaptation.Migration,whenvoluntary,safeandorderly,allowsreductionofriskstoclimaticandnon-climaticstressors.Forestbasedadaptationincludessustainableforestmanagement,forestconservationandrestoration,reforestationandafforestation.WASHreferstowater,sanitationandhygiene.Sixfeasibilitydimensions(economic,technological,institutional,social,environmentalandgeophysical)wereusedtocalculatethepotentialfeasibilityofclimateresponsesandadaptationoptions,alongwiththeirsynergieswithmitigation.Forpotentialfeasibilityandfeasibilitydimensions,theﬁgureshowshigh,medium,orlowfeasibility.Synergieswithmitigationareidentiﬁedashigh,medium,andlow.Theright-handsideofpanel(a)providesanoverviewofselectedmitigationoptionsandtheirestimatedcostsandpotentialsin2030.Relativepotentialsandcostswillvarybyplace,contextandtimeandinthelongertermcomparedto2030.Costsarenetlifetimediscountedmonetarycostsofavoidedgreenhousegasemissionscalculatedrelativetoareferencetechnology.Thepotential(horizontalaxis)isthequantityofnetGHGemissionreductionthatcanbeachievedbyagivenmitigationoptionrelativetoaspeciﬁedemissionbaseline.NetGHGemissionreductionsarethesumofreducedemissionsand/orenhancedsinks.Thebaselineusedconsistsofcurrentpolicy(around2019)referencescenariosfromtheAR6scenariosdatabase(25–75percentilevalues).Themitigationpotentialsareassessedindependentlyforeachoptionandarenotnecessarilyadditive.Healthsystemmitigationoptionsareincludedmostlyinsettlementandinfrastructure(e.g.,efﬁcienthealthcarebuildings)andcannotbeidentiﬁedseparately.Fuelswitchinginindustryreferstoswitchingtoelectricity,hydrogen,bioenergyandnaturalgas.Thelengthofthesolidbarsrepresentsthemitigationpotentialofanoption.Potentialsarebrokendownintocostcategories,indicatedbydifferentcolours(seelegend).Onlydiscountedlifetimemonetarycostsareconsidered.Whereagradualcolourtransitionisshown,thebreakdownofthepotentialintocostcategoriesisnotwellknownordependsheavilyonfactorssuchasgeographicallocation,resourceavailability,andregionalcircumstances,andthecoloursindicatetherangeofestimates.Theuncertaintyinthetotalpotentialistypically25–50%.Wheninterpretingthisﬁgure,thefollowingshouldbetakenintoaccount:(1)Themitigationpotentialisuncertain,asitwilldependonthereferencetechnology(andemissions)beingdisplaced,therateofnewtechnologyadoption,andseveralotherfactors;(2)Differentoptionshavedifferentfeasibilitiesbeyondthecostaspects,whicharenotreﬂectedintheﬁgure;and(3)Costsforaccommodatingtheintegrationofvariablerenewableenergysourcesinelectricitysystemsareexpectedtobemodestuntil2030,andarenotincluded.Panel(b)displaystheindicativepotentialofdemand-sidemitigationoptionsfor2050.Potentialsareestimatedbasedonapproximately500bottom-upstudiesrepresentingallglobalregions.Thebaseline(whitebar)isprovidedbythesectoralmeanGHGemissionsin2050ofthetwoscenarios(IEA-STEPSandIP_ModAct)consistentwithpoliciesannouncedbynationalgovernmentsuntil2020.Thegreenarrowrepresentsthedemand-sideemissionsreductionspotentials.Therangeinpotentialisshownbyalineconnectingdotsdisplayingthehighestandthelowestpotentialsreportedintheliterature.Foodshowsdemand-sidepotentialofsocio-culturalfactorsandinfrastructureuse,andchangesinland-usepatternsenabledbychangeinfooddemand.Demand-sidemeasuresandnewwaysofend-useserviceprovisioncanreduceglobalGHGemissionsinend-usesectors(buildings,landtransport,food)by40–70%by2050comparedtobaselinescenarios,whilesomeregionsandsocioeconomicgroupsrequireadditionalenergyandresources.Thelastrowshowshowdemand-sidemitigationoptionsinothersectorscaninﬂuenceoverallelectricitydemand.Thedarkgreybarshowstheprojectedincreaseinelectricitydemandabovethe2050baselineduetoincreasingelectriﬁcationintheothersectors.Basedonabottom-upassessment,thisprojectedincreaseinelectricitydemandcanbeavoidedthroughdemand-sidemitigationoptionsinthedomainsofinfrastructureuseandsocio-culturalfactorsthatinﬂuenceelectricityusageinindustry,landtransport,andbuildings(greenarrow).{WGIIFigureSPM.4,WGIICross-ChapterBoxFEASIBinChapter18;WGIIISPMC.10,WGIII12.2.1,WGIII12.2.2,WGIIIFigureSPM.6,WGIIIFigureSPM.7}SectioSnec4tion14.5.1.EnergySystemsconﬁdence).Themostfeasibleenergysystemadaptationoptionssupportinfrastructureresilience,reliablepowersystemsandefﬁcientRapidanddeepreductionsinGHGemissionsrequiremajorwateruseforexistingandnewenergygenerationsystems(veryenergysystemtransitions(highconﬁdence).Adaptationoptionshighconﬁdence).Adaptationsforhydropowerandthermo-electriccanhelpreduceclimate-relatedriskstotheenergysystempowergenerationareeffectiveinmostregionsupto1.5°Cto2°C,(veryhighconﬁdence).NetzeroCO2energysystemsentail:awithdecreasingeffectivenessathigherlevelsofwarming(mediumsubstantialreductioninoverallfossilfueluse,minimaluseofconﬁdence).Energygenerationdiversiﬁcation(e.g.,wind,solar,small-unabatedfossilfuels153,anduseofCarbonCaptureandStorageinscalehydroelectric)anddemandsidemanagement(e.g.,storageandtheremainingfossilfuelsystems;electricitysystemsthatemitnoenergyefﬁciencyimprovements)canincreaseenergyreliabilityandnetCO2;widespreadelectrification;alternativeenergycarriersinreducevulnerabilitiestoclimatechange,especiallyinruralpopulationsapplicationslessamenabletoelectrification;energyconservation(highconﬁdence).Climateresponsiveenergymarkets,updateddesignandefficiency;andgreaterintegrationacrosstheenergysystemstandardsonenergyassetsaccordingtocurrentandprojectedclimate(highconfidence).Largecontributionstoemissionsreductionscanchange,smart-gridtechnologies,robusttransmissionsystemsandcomefromoptionscostinglessthanUSD20tCO2-eq–1,includingimprovedcapacitytorespondtosupplydeﬁcitshavehighfeasibilitysolarandwindenergy,energyefﬁciencyimprovements,andCH4inthemedium-tolong-term,withmitigationco-beneﬁts(veryhigh(methane)emissionsreductions(fromcoalmining,oilandgas,andconﬁdence).{WGIISPMB.5.3,WGIISPMC.2.10;WGIIITS.5.1}waste)(mediumconfidence).154Manyoftheseresponseoptionsaretechnicallyviableandaresupportedbythepublic(highconfidence).4.5.2.IndustryMaintainingemission-intensivesystemsmay,insomeregionsandsectors,bemoreexpensivethantransitioningtolowemissionThereareseveraloptionstoreduceindustrialemissionssystems(highconfidence).{WGIISPMC.2.10;WGIIISPMC.4.1,thatdifferbytypeofindustry;manyindustriesaredisruptedWGIIISPMC.4.2,WGIIISPMC.12.1,WGIIISPME.1.1,WGIIITS.5.1}byclimatechange,especiallyfromextremeevents(highconﬁdence).ReducingindustryemissionswillentailcoordinatedClimatechangeandrelatedextremeeventswillaffectfutureenergyactionthroughoutvaluechainstopromoteallmitigationoptions,systems,includinghydropowerproduction,bioenergyyields,thermalincludingdemandmanagement,energyandmaterialsefﬁciency,powerplantefﬁciencies,anddemandsforheatingandcooling(highcircularmaterialﬂows,aswellasabatementtechnologiesand153Inthiscontext,‘unabatedfossilfuels’referstofossilfuelsproducedandusedwithoutinterventionsthatsubstantiallyreducetheamountofGHGemittedthroughoutthelifecycle;forexample,capturing90%ormoreCO2frompowerplants,or50–80%offugitivemethaneemissionsfromenergysupply.{WGIIISPMfootnote54}154Themitigationpotentialsandmitigationcostsofindividualtechnologiesinaspeciﬁccontextorregionmaydiffergreatlyfromtheprovidedestimates(mediumconﬁdence).{WGIIISPMC.12.1}104Near-TermResponsesinaChangingClimatetransformationalchangesinproductionprocesses(highconﬁdence).emissionconstructionmaterials,highlyefﬁcientbuildingenvelopeSection4Lightindustryandmanufacturingcanbelargelydecarbonizedthroughandtheintegrationofrenewableenergysolutions;attheusephase,availableabatementtechnologies(e.g.,materialefﬁciency,circularity),highlyefﬁcientappliances/equipment,theoptimisationoftheuseelectriﬁcation(e.g.,electrothermalheating,heatpumps),andswitchingofbuildingsandtheirsupplywithlow-emissionenergysources;tolow-andzero-GHGemittingfuels(e.g.,hydrogen,ammonia,andandatthedisposalphase,recyclingandre-usingconstructionbio-basedandothersyntheticfuels)(highconﬁdence),whiledeepmaterials.Sufﬁciency155measurescanlimitthedemandforenergyreductionofcementprocessemissionswillrelyoncementitiousandmaterialsoverthelifecycleofbuildingsandappliances.(highmaterialsubstitutionandtheavailabilityofCarbonCaptureandStorageconﬁdence){WGIISPMC.2.5;WGIIISPMC.7.2}(CCS)untilnewchemistriesaremastered(highconﬁdence).ReducingemissionsfromtheproductionanduseofchemicalswouldneedtorelyTransport-relatedGHGemissionscanbereducedbydemand-sideonalifecycleapproach,includingincreasedplasticsrecycling,fuelandoptionsandlow-GHGemissionstechnologies.Changesinurbanform,feedstockswitching,andcarbonsourcedthroughbiogenicsources,and,reallocationofstreetspaceforcyclingandwalking,digitalisationdependingonavailability,CarbonCaptureandUtilisation(CCU),direct(e.g.,teleworking)andprogramsthatencouragechangesinconsumerairCO2capture,aswellasCCS(highconﬁdence).Actiontoreducebehaviour(e.g.transport,pricing)canreducedemandfortransportindustrysectoremissionsmaychangethelocationofGHG-intensiveservicesandsupporttheshifttomoreenergyefﬁcienttransportindustriesandtheorganisationofvaluechains,withdistributionalmodes(highconﬁdence).Electricvehiclespoweredbylow-emissionseffectsonemploymentandeconomicstructure(mediumconﬁdence).electricityofferthelargestdecarbonisationpotentialforland-based{WGIITS.B.9.1,WGII16.5.2;WGIIISPMC.5,WGIIISPMC.5.2,transport,onalifecyclebasis(highconﬁdence).CostsofelectriﬁedWGIIISPMC.5.3,WGIIITS.5.5}vehiclesaredecreasingandtheiradoptionisaccelerating,buttheyrequirecontinuedinvestmentsinsupportinginfrastructuretoincreaseManyindustrialandservicesectorsarenegativelyaffectedbyclimatescaleofdeployment(highconﬁdence).Theenvironmentalfootprintofchangethroughsupplyandoperationaldisruptions,especiallyfrombatteryproductionandgrowingconcernsaboutcriticalmineralscanextremeevents(highconﬁdence),andwillrequireadaptationefforts.beaddressedbymaterialandsupplydiversiﬁcationstrategies,energyWaterintensiveindustries(e.g.,mining)canundertakemeasurestoandmaterialefﬁciencyimprovements,andcircularmaterialﬂowsreducewaterstress,suchaswaterrecyclingandreuse,usingbrackish(mediumconﬁdence).Advancesinbatterytechnologiescouldfacilitateorsalinesources,workingtoimprovewateruseefﬁciency.However,theelectriﬁcationofheavy-dutytrucksandcomplimentconventionalresidualriskswillremain,especiallyathigherlevelsofwarmingelectricrailsystems(mediumconﬁdence).Sustainablebiofuelscanoffer(mediumconﬁdence).{WGIITS.B.9.1,WGII16.5.2,WGII4.6.3}(Section3.2)additionalmitigationbeneﬁtsinland-basedtransportintheshortandmediumterm(mediumconﬁdence).Sustainablebiofuels,low-emissions4.5.3.Cities,SettlementsandInfrastructurehydrogen,andderivatives(includingsyntheticfuels)cansupportmitigationofCO2emissionsfromshipping,aviation,andheavy-dutyUrbansystemsarecriticalforachievingdeepemissionslandtransportbutrequireproductionprocessimprovementsandcostreductionsandadvancingclimateresilientdevelopment,reductions(mediumconﬁdence).Keyinfrastructuresystemsincludingparticularlywhenthisinvolvesintegratedplanningthatsanitation,water,health,transport,communicationsandenergywillincorporatesphysical,naturalandsocialinfrastructure(highbeincreasinglyvulnerableifdesignstandardsdonotaccountforconﬁdence).Deepemissionsreductionsandintegratedadaptationchangingclimateconditions(highconﬁdence).{WGIISPMB.2.5;actionsareadvancedby:integrated,inclusivelanduseplanningWGIIISPMC.6.2,WGIIISPMC.8,WGIIISPMC.8.1,WGIIISPMC.8.2,anddecision-making;compacturbanformbyco-locatingjobsandWGIIISPMC.10.2,WGIIISPMC.10.3,WGIIISPMC.10.4}housing;reducingorchangingurbanenergyandmaterialconsumption;electriﬁcationincombinationwithlowemissionssources;improvedGreen/naturalandblueinfrastructuresuchasurbanforestry,greenwaterandwastemanagementinfrastructure;andenhancingcarbonroofs,pondsandlakes,andriverrestorationcanmitigateclimatechangeuptakeandstorageintheurbanenvironment(e.g.bio-basedbuildingthroughcarbonuptakeandstorage,avoidedemissions,andreducedmaterials,permeablesurfacesandurbangreenandblueinfrastructure).energyusewhilereducingriskfromextremeeventssuchasheatwaves,Citiescanachievenetzeroemissionsifemissionsarereducedwithinheavyprecipitationanddroughts,andadvancingco-beneﬁtsforhealth,andoutsideoftheiradministrativeboundariesthroughsupplychains,well-beingandlivelihoods(mediumconﬁdence).Urbangreeningcancreatingbeneﬁcialcascadingeffectsacrossothersectors.(highconﬁdence)providelocalcooling(veryhighconﬁdence).Combininggreen/natural{WGIISPMC.5.6,WGIISPMD.1.3,WGIISPMD.3;WGIIISPMC.6,WGIIIandgrey/physicalinfrastructureadaptationresponseshaspotentialSPMC.6.2,WGIIITS5.4,SR1.5SPMC.2.4}toreduceadaptationcostsandcontributetoﬂoodcontrol,sanitation,waterresourcesmanagement,landslidepreventionandcoastalConsideringclimatechangeimpactsandrisks(e.g.,throughclimateprotection(mediumconﬁdence).Globally,moreﬁnancingisdirectedservices)inthedesignandplanningofurbanandruralsettlementsatgrey/physicalinfrastructurethangreen/naturalinfrastructureandinfrastructureiscriticalforresilienceandenhancinghumanandsocialinfrastructure(mediumconﬁdence),andthereislimitedwell-being.Effectivemitigationcanbeadvancedateachofthedesign,evidenceofinvestmentininformalsettlements(mediumtohighconstruction,retroﬁt,useanddisposalstagesforbuildings.Mitigationconﬁdence).Thegreatestgainsinwell-beinginurbanareascanbeinterventionsforbuildingsinclude:attheconstructionphase,low-achievedbyprioritisingﬁnancetoreduceclimateriskforlow-income155Asetofmeasuresanddailypracticesthatavoiddemandforenergy,materials,landandwaterwhiledeliveringhumanwell-beingforallwithinplanetaryboundaries.{WGIIIAnnexI}105Section4andmarginalisedcommunitiesincludingpeoplelivingininformalbyprotection,restoration,precautionaryecosystem-basedmanagementsettlements(highconﬁdence).{WGIISPMC.2.5,WGIISPMC.2.6,WGIIofrenewableresourceuse,andthereductionofpollutionandotherSPMC.2.7,WGIISPMD.3.2,WGIITS.E.1.4,WGIICross-ChapterBoxFEAS;stressors(highconfidence).{WGIISPMC.2.4,WGIISPMD.4;WGIIISPMC.6,WGIIISPMC.6.2,WGIIISPMD.1.3,WGIIISPMD.2.1}SROCCSPMC.2}SectioSnec4tion1Responsestoongoingsealevelriseandlandsubsidenceinlow-lyingLarge-scalelandconversionforbioenergy,biochar,orafforestationcoastalcitiesandsettlementsandsmallislandsincludeprotection,canincreaseriskstobiodiversity,waterandfoodsecurity.Incontrast,accommodation,advanceandplannedrelocation.Theseresponsesrestoringnaturalforestsanddrainedpeatlands,andimprovingaremoreeffectiveifcombinedand/orsequenced,plannedwellahead,sustainabilityofmanagedforestsenhancestheresilienceofcarbonalignedwithsocioculturalvaluesanddevelopmentpriorities,andstocksandsinksandreducesecosystemvulnerabilitytoclimatechange.underpinnedbyinclusivecommunityengagementprocesses.(highCooperation,andinclusivedecisionmaking,withlocalcommunitiesconﬁdence){WGIISPMC.2.8}andIndigenousPeoples,aswellasrecognitionofinherentrightsofIndigenousPeoples,isintegraltosuccessfuladaptationacross4.5.4.Land,Ocean,Food,andWaterforestsandotherecosystems.(highconfidence){WGIISPMB.5.4,WGIISPMC.2.3,WGIISPMC.2.4;WGIIISPMD.2.3;SRCCLB.7.3,ThereissubstantialmitigationandadaptationpotentialfromSRCCLSPMC.4.3,SRCCLTS.7}optionsinagriculture,forestryandotherlanduse,andintheoceans,thatcouldbeupscaledintheneartermacrossmostNaturalrivers,wetlandsandupstreamforestsreduceﬂoodriskinmostregions(highconﬁdence)(Figure4.5).Conservation,improvedcircumstances(highconﬁdence).Enhancingnaturalwaterretentionmanagement,andrestorationofforestsandotherecosystemsoffersuchasbyrestoringwetlandsandrivers,landuseplanningsuchasnothelargestshareofeconomicmitigationpotential,withreducedbuildzonesorupstreamforestmanagement,canfurtherreduceﬂoodriskdeforestationintropicalregionshavingthehighesttotalmitigation(mediumconﬁdence).Forinlandﬂooding,combinationsofnon-structuralpotential.Ecosystemrestoration,reforestation,andafforestationcanmeasureslikeearlywarningsystemsandstructuralmeasureslikeleveesleadtotrade-offsduetocompetingdemandsonland.Minimizinghavereducedlossoflives(mediumconfidence),butharddefencestrade-offsrequiresintegratedapproachestomeetmultipleobjectivesagainstfloodingorsealevelrisecanalsobemaladaptiveincludingfoodsecurity.Demand-sidemeasures(shiftingtosustainable(highconﬁdence).{WGIISPMC.2.1,WGIISPMC.4.1,WGIISPMC.4.2,healthydietsandreducingfoodloss/waste)andsustainableagriculturalWGIISPMC.2.5}intensiﬁcationcanreduceecosystemconversionandCH4andN2Oemissions,andfreeuplandforreforestationandecosystemrestoration.Protectionandrestorationofcoastal‘bluecarbon’ecosystemsSustainablysourcedagricultureandforestproducts,including(e.g.,mangroves,tidalmarshesandseagrassmeadows)couldlong-livedwoodproducts,canbeusedinsteadofmoreGHG-intensivereduceemissionsand/orincreasecarbonuptakeandstorage(mediumproductsinothersectors.Effectiveadaptationoptionsincludecultivarconﬁdence).Coastalwetlandsprotectagainstcoastalerosionimprovements,agroforestry,community-basedadaptation,farmandandﬂooding(veryhighconﬁdence).Strengtheningprecautionarylandscapediversiﬁcation,andurbanagriculture.TheseAFOLUresponseapproaches,suchasrebuildingoverexploitedordepletedﬁsheries,andoptionsrequireintegrationofbiophysical,socioeconomicandotherresponsivenessofexistingﬁsheriesmanagementstrategiesreducesenablingfactors.Theeffectivenessofecosystem-basedadaptationnegativeclimatechangeimpactsonﬁsheries,withbeneﬁtsforregionalandmostwater-relatedadaptationoptionsdeclineswithincreasingeconomiesandlivelihoods(mediumconﬁdence).Ecosystem-basedwarming(see3.2).(highconﬁdence){WGIISPMC.2.1,WGIISPMC.2.2,managementinfisheriesandaquaculturesupportsfoodsecurity,WGIISPMC.2.5;WGIIISPMC.9.1;SRCCLSPMB.1.1,SRCCLSPMB.5.4,biodiversity,humanhealthandwell-being(highconfidence).SRCCLSPMD.1;SROCCSPMC}{WGIISPMC.2.2,WGIISPMC.2;SROCCSPMC2.3,SROCCSPMC.2.4}Someoptions,suchasconservationofhigh-carbonecosystems4.5.5.HealthandNutrition(e.g.,peatlands,wetlands,rangelands,mangrovesandforests),haveimmediateimpactswhileothers,suchasrestorationofhigh-carbonHumanhealthwillbeneﬁtfromintegratedmitigationandecosystems,reclamationofdegradedsoilsorafforestation,takedecadesadaptationoptionsthatmainstreamhealthintofood,todelivermeasurableresults(highconﬁdence).Manysustainablelandinfrastructure,socialprotection,andwaterpolicies(veryhighmanagementtechnologiesandpracticesareﬁnanciallyproﬁtableinthreeconﬁdence).Balancedandsustainablehealthydiets156andreducedtotenyears(mediumconﬁdence).{SRCCLSPMB.1.2,SRCCLSPMD.2.2}foodlossandwastepresentimportantopportunitiesforadaptationandmitigationwhilegeneratingsigniﬁcantco-beneﬁtsintermsMaintainingtheresilienceofbiodiversityandecosystemofbiodiversityandhumanhealth(highconﬁdence).Publichealthservicesataglobalscaledependsoneffectiveandequitablepoliciestoimprovenutrition,suchasincreasingthediversityoffoodconservationofapproximately30–50%ofEarth’sland,sourcesinpublicprocurement,healthinsurance,ﬁnancialincentives,freshwaterandoceanareas,includingcurrentlynear-naturalandawareness-raisingcampaigns,canpotentiallyinfluencefoodecosystems(highconﬁdence).Theservicesandoptionsprovidedbydemand,reducefoodwaste,reducehealthcarecosts,contributetoterrestrial,freshwater,coastalandoceanecosystemscanbesupportedlowerGHGemissionsandenhanceadaptivecapacity(highconﬁdence).156Balanceddietsrefertodietsthatfeatureplant-basedfoods,suchasthosebasedoncoarsegrains,legumes,fruitsandvegetables,nutsandseeds,andanimal-sourcedfoodproducedinresilient,sustainableandlow-GHGemissionsystems,asdescribedinSRCCL.106Near-TermResponsesinaChangingClimateImprovedaccesstocleanenergysourcesandtechnologies,andshiftsIntegratingclimateadaptationintosocialprotectionprograms,toactivemobility(e.g.,walkingandcycling)andpublictransportcanincludingcashtransfersandpublicworksprograms,ishighlyfeasibledeliversocioeconomic,airqualityandhealthbenefits,especiallyandincreasesresiliencetoclimatechange,especiallywhensupportedforwomenandchildren(highconfidence).{WGIISPMC.2.2,WGIIbybasicservicesandinfrastructure(highconﬁdence).SocialsafetynetsSPMC.2.11,WGIICross-ChapterBoxHEALTH;WGIIISPMC.2.2,canbuildadaptivecapacities,reducesocioeconomicvulnerability,andWGIIISPMC.4.2,WGIIISPMC.9.1,WGIIISPMC.10.4,WGIIISPMreducerisklinkedtohazards(robustevidence,mediumagreement).D.1.3,WGIIIFigureSPM.6,WGIIIFigureSPM.8;SRCCLSPMB.6.2,{WGIISPMC.2.9,WGIISPMC.2.13,WGIICross-ChapterBoxFEASIBinSRCCLSPMB.6.3,SRCCLB.4.6,SRCCLSPMC.2.4}Chapter18;SRCCLSPMC.1.4,SRCCLSPMD.1.2}EffectiveadaptationoptionsexisttohelpprotecthumanhealthReducingfuturerisksofinvoluntarymigrationanddisplacementSection4andwell-being(highconﬁdence).HealthActionPlansthatincludeduetoclimatechangeispossiblethroughcooperative,internationalearlywarningandresponsesystemsareeffectiveforextremeheat(higheffortstoenhanceinstitutionaladaptivecapacityandsustainableconﬁdence).Effectiveoptionsforwater-borneandfood-bornediseasesdevelopment(highconﬁdence).Increasingadaptivecapacityminimisesincludeimprovingaccesstopotablewater,reducingexposureofwaterandriskassociatedwithinvoluntarymigrationandimmobilityandimprovessanitationsystemstoﬂoodingandextremeweatherevents,andimprovedthedegreeofchoiceunderwhichmigrationdecisionsaremade,whileearlywarningsystems(veryhighconﬁdence).Forvector-bornediseases,policyinterventionscanremovebarriersandexpandthealternativesforeffectiveadaptationoptionsincludesurveillance,earlywarningsafe,orderlyandregularmigrationthatallowsvulnerablepeopletoadaptsystems,andvaccinedevelopment(veryhighconﬁdence).Effectivetoclimatechange(highconﬁdence).{WGIISPMC.2.12,WGIITS.D.8.6,adaptationoptionsforreducingmentalhealthrisksunderclimateWGIICross-ChapterBoxMIGRATEinChapter7}changeincludeimprovingsurveillanceandaccesstomentalhealthcare,andmonitoringofpsychosocialimpactsfromextremeweatherAcceleratingcommitmentandfollow-throughbytheprivateevents(highconﬁdence).Akeypathwaytoclimateresilienceinthesectorispromotedforinstancebybuildingbusinesscasesforhealthsectorisuniversalaccesstohealthcare(highconﬁdence).adaptation,accountabilityandtransparencymechanisms,and{WGIISPMC.2.11,WGII7.4.6}monitoringandevaluationofadaptationprogress(mediumconﬁdence).Integratedpathwaysformanagingclimateriskswill4.5.6Society,Livelihoods,andEconomiesbemostsuitablewhenso-called‘low-regret’anticipatoryoptionsareestablishedjointlyacrosssectorsinatimelymannerandarefeasibleEnhancingknowledgeonrisksandavailableadaptationoptionsandeffectiveintheirlocalcontext,andwhenpathdependenciesandpromotessocietalresponses,andbehaviourandlifestylechangesmaladaptationsacrosssectorsareavoided(highconﬁdence).Sustainedsupportedbypolicies,infrastructureandtechnologycanhelpadaptationactionsarestrengthenedbymainstreamingadaptationintoreduceglobalGHGemissions(highconﬁdence).Climateliteracyinstitutionalbudgetandpolicyplanningcycles,statutoryplanning,andinformationprovidedthroughclimateservicesandcommunitymonitoringandevaluationframeworksandintorecoveryeffortsapproaches,includingthosethatareinformedbyIndigenousKnowledgefromdisasterevents(highconﬁdence).Instrumentsthatincorporateandlocalknowledge,canacceleratebehaviouralchangesandplanningadaptationsuchaspolicyandlegalframeworks,behaviouralincentives,(highconﬁdence).Educationalandinformationprogrammes,usingandeconomicinstrumentsthataddressmarketfailures,suchasthearts,participatorymodellingandcitizensciencecanfacilitateclimateriskdisclosure,inclusiveanddeliberativeprocessesstrengthenawareness,heightenriskperception,andinﬂuencebehaviours(highadaptationactionsbypublicandprivateactors(mediumconﬁdence).conﬁdence).Thewaychoicesarepresentedcanenableadoptionoflow{WGIISPMC.5.1,WGIISPMC.5.2,WGIITS.D.10.4}GHGintensivesocio-culturaloptions,suchasshiftstobalanced,sustainablehealthydiets,reducedfoodwaste,andactivemobility(highconﬁdence).Judiciouslabelling,framing,andcommunicationofsocialnormscanincreasetheeffectofmandates,subsidies,ortaxes(mediumconﬁdence).{WGIISPMC.5.3,WGIITS.D.10.1;WGIIISPMC.10,WGIIISPMC.10.2,WGIIISPMC.10.3,WGIIISPME.2.2,WGIIIFigureSPM.6,WGIIITS.6.1,5.4;SR1.5SPMD.5.6;SROCCSPMC.4}Arangeofadaptationoptions,suchasdisasterriskmanagement,earlywarningsystems,climateservicesandriskspreadingandsharingapproaches,havebroadapplicabilityacrosssectorsandprovidegreaterriskreductionbeneﬁtswhencombined(highconﬁdence).Climateservicesthataredemand-drivenandinclusiveofdifferentusersandproviderscanimproveagriculturalpractices,informbetterwateruseandefﬁciency,andenableresilientinfrastructureplanning(highconﬁdence).Policymixesthatincludeweatherandhealthinsurance,socialprotectionandadaptivesafetynets,contingentﬁnanceandreservefunds,anduniversalaccesstoearlywarningsystemscombinedwitheffectivecontingencyplans,canreducevulnerabilityandexposureofhumansystems(highconﬁdence).107Section44.6Co-BeneﬁtsofAdaptationandMitigationforSustainableDevelopmentGoalsMitigationandadaptationactionshavemoresynergiesthantrade-offswithSustainableDevelopmentGoals(SDGs).Synergiesandtrade-offsdependoncontextandscaleofimplementation.Potentialtrade-offscanbecompensatedoravoidedwithadditionalpolicies,investmentsandﬁnancialpartnerships.(highconﬁdence)SectioSnec4tion1ManymitigationandadaptationactionshavemultiplesynergiesandothersocialequityconsiderationswithmeaningfulparticipationwithSustainableDevelopmentGoals(SDGs),butsomeactionsofIndigenousPeoples,localcommunitiesandvulnerablepopulations.canalsohavetrade-offs.PotentialsynergieswithSDGsexceed(highconﬁdence).{WGIISPMC.2.9,WGIISPMC.5.6,WGIISPMD.5.2,potentialtrade-offs.Synergiesandtrade-offsarecontextspecificWGIICross-ChapterBoxonGenderinChapter18;WGIIISPMC.9.2,anddependon:meansandscaleofimplementation,intra-andWGIIISPMD.1.2,WGIIISPMD.1.4,WGIIISPMD.2;SRCCLSPMD.2.2,SRCCLTS.4}inter-sectoralinteractions,cooperationbetweencountriesandregions,thesequencing,timingandstringencyofactions,governance,andContextrelevantdesignandimplementationrequirespolicydesign.Eradicatingextremepoverty,energypoverty,andconsideringpeople’sneeds,biodiversity,andothersustainableprovidingdecentlivingstandardstoall,consistentwithnear-developmentdimensions(veryhighconﬁdence).Countriesattermsustainabledevelopmentobjectives,canbeachievedallstagesofeconomicdevelopmentseektoimprovethewell-beingwithoutsignificantglobalemissionsgrowth.(highconfidence)ofpeople,andtheirdevelopmentprioritiesreﬂectdifferentstarting{WGIISPMC.2.3,WGIIFigureSPM.4b;WGIIISPMB.3.3,WGIIISPMC.9.2,pointsandcontexts.DifferentcontextsincludebutarenotlimitedtoWGIIISPMD.1.2,WGIIISPMD.1.4,WGIIIFigureSPM.8}(Figure4.5)social,economic,environmental,cultural,orpoliticalcircumstances,resourceendowment,capabilities,internationalenvironment,andpriorSeveralmitigationandadaptationoptionscanharnessnear-development.nregionswithhighdependencyonfossilfuelsfor,amongtermsynergiesandreducetrade-offstoadvancesustainableotherthings,revenueandemploymentgeneration,mitigatingrisksfordevelopmentinenergy,urbanandlandsystems(Figure4.5)sustainabledevelopmentrequirespoliciesthatpromoteeconomicand(highconﬁdence).Cleanenergysupplysystemshavemultipleenergysectordiversiﬁcationandconsiderationsofjusttransitionsco-benefits,includingimprovementsinairqualityandhealth.principles,processesandpractices(highconﬁdence).ForindividualsandHeatHealthActionPlansthatincludeearlywarningandresponsehouseholdsinlow-lyingcoastalareas,inSmallIslands,andsmallholdersystems,approachesthatmainstreamhealthintofood,livelihoods,farmerstransitioningfromincrementaltotransformationaladaptationsocialprotection,waterandsanitationbenefithealthandwell-canhelpovercomesoftadaptationlimits(highconﬁdence).Effectivebeing.TherearepotentialsynergiesbetweenmultipleSustainablegovernanceisneededtolimittrade-offsofsomemitigationoptionsDevelopmentGoalsandsustainablelanduseandurbanplanningsuchaslargescaleafforestationandbioenergyoptionsduetoriskswithmoregreenspaces,reducedairpollution,anddemand-sidefromtheirdeploymentforfoodsystems,biodiversity,otherecosystemmitigationincludingshiftstobalanced,sustainablehealthydiets.functionsandservices,andlivelihoods(highconﬁdence).EffectiveElectriﬁcationcombinedwithlow-GHGenergy,andshiftstopublicgovernancerequiresadequateinstitutionalcapacityatalllevelstransportcanenhancehealth,employment,andcancontributeto(highconfidence).{WGIISPMB.5.4,WGIISPMC.3.1,WGIISPMenergysecurityanddeliverequity.Conservation,protectionandC.3.4;WGIIISPMD.1.3,WGIIISPME.4.2;SR1.5SPMC.3.4,restorationofterrestrial,freshwater,coastalandoceanecosystems,SR1.5SPMC.3.5,SR1.5SPMFigureSPM.4,SR1.5SPMD.4.3,togetherwithtargetedmanagementtoadapttounavoidableimpactsSR1.5SPMD.4.4}ofclimatechangecangeneratemultipleadditionalbeneﬁts,suchasagriculturalproductivity,foodsecurity,andbiodiversityconservation.(highconfidence){WGIISPMC.1.1,WGIIC.2.4,WGIISPMD.1,WGIIFigureSPM.4,WGIICross-ChapterBoxHEALTHinChapter17,WGIICross-ChapterBoxFEASIBinChapter18;WGIIISPMC.4.2,WGIIISPMD.1.3,WGIIISPMD.2,WGIIIFigureSPM.8;SRCCLSPMB.4.6}Whenimplementingmitigationandadaptationtogether,andtakingtrade-offsintoaccount,multipleco-beneﬁtsandsynergiesforhumanwell-beingaswellasecosystemandplanetaryhealthcanberealised(highconﬁdence).Thereisastronglinkbetweensustainabledevelopment,vulnerabilityandclimaterisks.Socialsafetynetsthatsupportclimatechangeadaptationhavestrongco-beneﬁtswithdevelopmentgoalssuchaseducation,povertyalleviation,genderinclusionandfoodsecurity.Landrestorationcontributestomitigationandadaptationwithsynergiesviaenhancedecosystemservicesandwitheconomicallypositivereturnsandco-beneﬁtsforpovertyreductionandimprovedlivelihoods.Trade-offscanbeevaluatedandminimisedbygivingemphasistocapacitybuilding,ﬁnance,technologytransfer,investments;governance,development,contextspeciﬁcgender-based108Near-TermResponsesinaChangingClimateNear-termadaptationandmitigationactionshavemoresynergiesthantrade-offswithSustainableDevelopmentGoals(SDGs)Synergiesandtrade-offsdependoncontextandscaleSDGsEnergysystemsUrbanandinfrastructureLandsystemOceanSociety,Industryecosystemslivelihoods,andMitigationAdaptationMitigationAdaptationMitigationAdaptationMitigationAdaptationeconomiesAdaptationSection4KeySynergiesTrade-offsBothsynergiesandtrade-offs/mixedLimitedevidence/noevidence/noassessmentFigure4.5:Potentialsynergiesandtrade-offsbetweentheportfolioofclimatechangemitigationandadaptationoptionsandtheSustainableDevelopmentGoals(SDGs).Thisﬁgurepresentsahigh-levelsummaryofpotentialsynergiesandtrade-offsassessedinWGIIFigureSPM.4bandWGIIIFigureSPM.8,basedonthequalitativeandquantitativeassessmentofeachindividualmitigationoroption.TheSDGsserveasananalyticalframeworkfortheassessmentofdifferentsustainabledevelopmentdimensions,whichextendbeyondthetimeframeof2030SDGtargets.Synergiesandtrade-offsacrossallindividualoptionswithinasector/systemareaggregatedintosector/systempotentialsforthewholemitigationoradaptationportfolio.Thelengthofeachbarrepresentsthetotalnumberofmitigationoradaptationoptionsundereachsystem/sector.Thenumberofadaptationandmitigationoptionsvaryacrosssystem/sector,andhavebeennormalisedto100%sothatbarsarecomparableacrossmitigation,adaptation,system/sector,andSDGs.PositivelinksshowninWGIIFigureSPM.4bandWGIIIFigureSPM.8arecountedandaggregatedtogeneratethepercentageshareofsynergies,representedherebytheblueproportionwithinthebars.NegativelinksshowninWGIIFigureSPM.4bandWGIIIFigureSPM.8arecountedandaggregatedtogeneratethepercentageshareoftrade-offsandisrepresentedbyorangeproportionwithinthebars.‘Bothsynergiesandtrade-offs’showninWGIIFigureSPM.4bWGIIIFigureSPM.8arecountedandaggregatedtogeneratethepercentageshareof‘bothsynergiesandtrade-off’,representedbythestripedproportionwithinthebars.The‘white’proportionwithinthebarindicateslimitedevidence/noevidence/notassessed.EnergysystemscompriseallmitigationoptionslistedinWGIIIFigureSPM.8andWGIIFigureSPM.4bforadaptation.Urbanandinfrastructurecomprisesallmitigationoptionslisted109Section4inWGIIIFigureSPM.8underUrbansystems,underBuildingsandunderTransportandadaptationoptionslistedinWGIIFigureSPM.4bunderUrbanandinfrastructuresystems.LandsystemcomprisesmitigationoptionslistedinWGIIIFigureSPM.8underAFOLUandadaptationoptionslistedinWGIIFigureSPM.4bunderLandandoceansystems:forest-basedadaptation,agroforestry,biodiversitymanagementandecosystemconnectivity,improvedcroplandmanagement,efﬁcientlivestockmanagement,wateruseefﬁciencyandwaterresourcemanagement.OceanecosystemscomprisesadaptationoptionslistedinWGIIFigureSPM.4bunderLandandoceansystems:coastaldefenceandhardening,integratedcoastalzonemanagementandsustainableaquacultureandﬁsheries.Society,livelihoodandeconomiescomprisesadaptationoptionslistedinWGIIFigureSPM.4bunderCross-sectoral;IndustrycomprisesallthosemitigationoptionslistedinWGIIIFigureSPM.8underIndustry.SDG13(ClimateAction)isnotlistedbecausemitigation/adaptationisbeingconsideredintermsofinteractionwithSDGsandnotviceversa(SPMSR1.5FigureSPM.4caption).ThebarsdenotethestrengthoftheconnectionanddonotconsiderthestrengthoftheimpactontheSDGs.Thesynergiesandtrade-offsdifferdependingonthecontextandthescaleofimplementation.Scaleofimplementationparticularlymatterswhenthereiscompetitionforscarceresources.Forthesakeofuniformity,wearenotreportingtheconﬁdencelevelsbecausethereisknowledgegapinadaptationoptionwiserelationwithSDGsandtheirconﬁdencelevelwhichisevidentfromWGIIﬁgSPM.4b.{WGIIFigureSPM.4b;WGIIIFigureSPM.8}4.7GovernanceandPolicyforNear-TermClimateChangeActionEffectiveclimateactionrequirespoliticalcommitment,well-alignedmulti-levelgovernanceandinstitutionalframeworks,laws,policiesandstrategies.Itneedscleargoals,adequateﬁnanceandﬁnancingtools,coordinationacrossmultiplepolicydomains,andinclusivegovernanceprocesses.Manymitigationandadaptationpolicyinstrumentshavebeendeployedsuccessfully,andcouldsupportdeepemissionsreductionsandclimateresilienceifscaledupandappliedwidely,dependingonnationalcircumstances.Adaptationandmitigationactionbeneﬁtsfromdrawingondiverseknowledge.(highconﬁdence)SectioSnec4tion1EffectiveclimategovernanceenablesmitigationandadaptationEffectiveclimategovernanceisenabledbyinclusivedecisionbyprovidingoveralldirectionbasedonnationalcircumstances,processes,allocationofappropriateresources,andinstitutionalsettingtargetsandpriorities,mainstreamingclimateactionacrossreview,monitoringandevaluation(highconﬁdence).Multi-level,policydomainsandlevels,basedonnationalcircumstancesandhybridandcross-sectorgovernancefacilitatesappropriateconsiderationinthecontextofinternationalcooperation.Effectivegovernanceforco-beneﬁtsandtrade-offs,particularlyinlandsectorswheredecisionenhancesmonitoringandevaluationandregulatorycertainty,processesrangefromfarmleveltonationalscale(highconﬁdence).prioritisinginclusive,transparentandequitabledecision-making,Considerationofclimatejusticecanhelptofacilitateshiftingdevelopmentandimprovesaccesstoﬁnanceandtechnology(highconﬁdence).pathwaystowardssustainability.{WGIISPMC.5.5,WGIISPMC.5.6,Thesefunctionscanbepromotedbyclimate-relevantlawsandWGIISPMD.1.1,WGIISPMD.2,WGIISPMD.3.2;SRCCLSPMC.3,plans,whicharegrowinginnumberacrosssectorsandregions,SRCCLTS.1}advancingmitigationoutcomesandadaptationbenefits(highconfidence).ClimatelawshavebeengrowinginnumberandDrawingondiverseknowledgeandpartnerships,includinghavehelpeddelivermitigationandadaptationoutcomes(mediumwithwomen,youth,IndigenousPeoples,localcommunities,andconﬁdence).{WGIISPMC.5,WGIISPMC.5.1,WGIISPMC5.4,WGIISPMC.5.6;ethnicminoritiescanfacilitateclimateresilientdevelopmentWGIIISPMB.5.2,WGIIISPME.3.1}andhasallowedlocallyappropriateandsociallyacceptablesolutions(highconﬁdence).{WGIISPMD.2,D.2.1}Effectivemunicipal,nationalandsub-nationalclimateinstitutions,suchasexpertandco-ordinatingbodies,enableManyregulatoryandeconomicinstrumentshavealreadybeenco-produced,multi-scaledecision-processes,buildconsensusdeployedsuccessfully.Theseinstrumentscouldsupportdeepforactionamongdiverseinterests,andinformstrategysettingsemissionsreductionsifscaledupandappliedmorewidely.(highconﬁdence).ThisrequiresadequateinstitutionalcapacityatPracticalexperiencehasinformedinstrumentdesignandhelpedtoalllevels(highconﬁdence).Vulnerabilitiesandclimaterisksareoftenimprovepredictability,environmentaleffectiveness,economicefﬁciency,reducedthroughcarefullydesignedandimplementedlaws,policies,andequity.(highconﬁdence){WGIISPME.4;WGIIISPME.4.2}participatoryprocesses,andinterventionsthataddresscontextspeciﬁcinequitiessuchasbasedongender,ethnicity,disability,age,Scalingupandenhancingtheuseofregulatoryinstruments,locationandincome(highconﬁdence).Policysupportisinﬂuencedbyconsistentwithnationalcircumstances,canimprovemitigationIndigenousPeoples,businesses,andactorsincivilsociety,including,outcomesinsectoralapplications(highconﬁdence),andyouth,labour,media,andlocalcommunities,andeffectivenessisregulatoryinstrumentsthatincludeﬂexibilitymechanismsenhancedbypartnershipsbetweenmanydifferentgroupsinsocietycanreducecostsofcuttingemissions(mediumconﬁdence).(highconﬁdence).Climate-relatedlitigationisgrowing,withalarge{WGIISPMC.5.4;WGIIISPME.4.1}numberofcasesinsomedevelopedcountriesandwithamuchsmallernumberinsomedevelopingcountries,andinsomecaseshasinﬂuencedWhereimplemented,carbonpricinginstrumentshaveincentivizedtheoutcomeandambitionofclimategovernance(mediumconﬁdence).low-costemissionsreductionmeasures,buthavebeenless{WGIISPMC2.6,WGIISPMC.5.2,WGIISPMC.5.5,WGIISPMC.5.6,effective,ontheirownandatprevailingpricesduringtheWGIISPMD.3.1;WGIIISPME3.2,WGIIISPME.3.3}assessmentperiod,topromotehigher-costmeasuresnecessaryforfurtherreductions(mediumconﬁdence).Revenuefromcarbontaxesoremissionstradingcanbeusedforequityanddistributionalgoals,forexampletosupportlow-incomehouseholds,amongother110Near-TermResponsesinaChangingClimateapproaches(highconﬁdence).ThereisnoconsistentevidencethatNationalpoliciestosupporttechnologydevelopment,andcurrentemissiontradingsystemshaveledtosigniﬁcantemissionsparticipationininternationalmarketsforemissionreduction,leakage(mediumconﬁdence).{WGIIISPME4.2,WGIIISPME.4.6}canbringpositivespillovereffectsforothercountries(mediumconﬁdence),althoughreduceddemandforfossilfuelsasRemovingfossilfuelsubsidieswouldreduceemissions,improvearesultofclimatepolicycouldresultincoststoexportingcountriespublicrevenueandmacroeconomicperformance,andyield(highconfidence).Economy-widepackagescanmeetshort-termotherenvironmentalandsustainabledevelopmentbeneﬁtssucheconomicgoalswhilereducingemissionsandshiftingdevelopmentasimprovedpublicrevenue,macroeconomicandsustainabilitypathwaystowardssustainability(mediumconfidence).Examplesperformance;subsidyremovalcanhaveadversedistributionalarepublicspendingcommitments;pricingreforms;andinvestmentimpactsespeciallyonthemosteconomicallyvulnerableineducationandtraining,R&Dandinfrastructure(highconfidence).groupswhich,insomecases,canbemitigatedbymeasuresEffectivepolicypackageswouldbecomprehensiveincoverage,suchasre-distributingrevenuesaved,anddependonnationalharnessedtoaclearvisionforchange,balancedacrossobjectives,circumstances(highconﬁdence).Fossilfuelsubsidyremovalisalignedwithspecifictechnologyandsystemneeds,consistentprojectedbyvariousstudiestoreduceglobalCO2emissionsby1–4%,intermsofdesignandtailoredtonationalcircumstances(highandGHGemissionsbyupto10%by2030,varyingacrossregionsconfidence).{WGIIISPME4.4,WGIIISPM4.5,WGIIISPM4.6}(mediumconﬁdence).{WGIIISPME.4.2}4.8StrengtheningtheResponse:Finance,InternationalCooperationandTechnologyFinance,internationalcooperationandtechnologyarecriticalenablersforacceleratedclimateaction.Ifclimategoalsaretobeachieved,bothadaptationandmitigationﬁnancingwouldhavetoincreasemany-fold.Thereissufﬁcientglobalcapitaltoclosetheglobalinvestmentgapsbuttherearebarrierstoredirectcapitaltoclimateaction.Barriersincludeinstitutional,regulatoryandmarketaccessbarriers,whichcanbereducedtoaddresstheneedsandopportunities,economicvulnerabilityandindebtednessinmanydevelopingcountries.Enhancinginternationalcooperationispossiblethroughmultiplechannels.Enhancingtechnologyinnovationsystemsiskeytoacceleratethewidespreadadoptionoftechnologiesandpractices.(highconﬁdence)4.8.1.FinanceforMitigationandAdaptationActionssomerelatedlossesanddamages,particularlyinvulnerabledevelopingSection4countries(highconﬁdence).EnhancedmobilisationofandaccesstoImprovedavailabilityandaccesstoﬁnance157willenableﬁnance,togetherwithbuildingcapacity,areessentialforimplementationacceleratedclimateaction(veryhighconﬁdence).Addressingofadaptationactionsandtoreduceadaptationgapsgivenrisingrisksneedsandgapsandbroadeningequitableaccesstodomesticandandcosts,especiallyforthemostvulnerablegroups,regionsandsectorsinternationalﬁnance,whencombinedwithothersupportiveactions,can(highconﬁdence).Publicﬁnanceisanimportantenablerofadaptationactasacatalystforacceleratingmitigationandshiftingdevelopmentandmitigation,andcanalsoleverageprivateﬁnance(highconﬁdence).pathways(highconﬁdence).ClimateresilientdevelopmentisenabledAdaptationfundingpredominatelycomesfrompublicsources,andbyincreasedinternationalcooperationincludingimprovedaccesspublicmechanismsandﬁnancecanleverageprivatesectorﬁnancebytoﬁnancialresources,particularlyforvulnerableregions,sectorsaddressingrealandperceivedregulatory,costandmarketbarriers,forandgroups,andinclusivegovernanceandcoordinatedpolicies(highinstanceviapublic-privatepartnerships(highconﬁdence).Financialandconﬁdence).Acceleratedinternationalﬁnancialcooperationisacriticaltechnologicalresourcesenableeffectiveandongoingimplementationenableroflow-GHGandjusttransitions,andcanaddressinequitiesinofadaptation,especiallywhensupportedbyinstitutionswithastrongaccesstoﬁnanceandthecostsof,andvulnerabilityto,theimpactsofunderstandingofadaptationneedsandcapacity(highconﬁdence).climatechange(highconﬁdence).{WGIISPMC.1.2,WGIISPMC.3.2,AverageannualmodelledmitigationinvestmentrequirementsforWGIISPMC.5,WGIISPMC.5.4,WGIISPMD.2,WGIISPMD.3.2,2020to2030inscenariosthatlimitwarmingto2°Cor1.5°CareaWGIISPMD.5,WGIISPMD.5.2;WGIIISPMB.4.2,WGIIISPMB.5,factorofthreetosixgreaterthancurrentlevels,andtotalmitigationWGIIISPMB.5.4,WGIIISPMC.4.2,WGIIISPMC.7.3,WGIIISPMC.8.5,investments(public,private,domesticandinternational)wouldneedWGIIISPMD.1.2,WGIIISPMD.2.4,WGIIISPMD.3.4,WGIIISPME.2.3,toincreaseacrossallsectorsandregions(mediumconﬁdence).EvenWGIIISPME.3.1,WGIIISPME.5,WGIIISPME.5.1,WGIIISPME.5.2,ifextensiveglobalmitigationeffortsareimplemented,therewillbeaWGIIISPME.5.3,WGIIISPME.5.4,WGIIISPME.6.2}largeneedforﬁnancial,technical,andhumanresourcesforadaptation(highconﬁdence).{WGIISPMC.1.2,WGIISPMC2.11,WGIISPMC.3,Bothadaptationandmitigationﬁnanceneedtoincreasemany-fold,WGIISPMC.3.2,WGIISPMC3.5,WGIISPMC.5,WGIISPMC.5.4,toaddressrisingclimaterisksandtoaccelerateinvestmentsinWGIISPMD.1,WGIISPMD.1.1,WGIISPMD.1.2,WGIISPMC.5.4;emissionsreduction(highconﬁdence).IncreasedﬁnancewouldWGIIISPMD.2.4,WGIIISPME.5,WGIIISPME.5.1,WGIII15.2}addresssoftlimitstoadaptationandrisingclimateriskswhilealsoaverting(Section2.3.2,2.3.3,4.4,Figure4.6)157Financecanoriginatefromdiversesources,singlyorincombination:publicorprivate,local,nationalorinternational,bilateralormultilateral,andalternativesources(e.g.,philanthropic,carbonoffsets).Itcanbeintheformofgrants,technicalassistance,loans(concessionalandnon-concessional),bonds,equity,riskinsuranceandﬁnancialguarantees(ofvarioustypes).111Section4SectioSnec4tion1Thereissufﬁcientglobalcapitalandliquiditytocloseglobal4.8.2.InternationalCooperationandCoordinationinvestmentgaps,giventhesizeoftheglobalﬁnancialsystem,buttherearebarrierstoredirectcapitaltoclimateactionInternationalcooperationisacriticalenablerforachievingbothwithinandoutsidetheglobalﬁnancialsectorandintheambitiousclimatechangemitigationgoalsandclimateresilientcontextofeconomicvulnerabilitiesandindebtednessfacingdevelopment(highconﬁdence).Climateresilientdevelopmentismanydevelopingcountries(highconﬁdence).Forshiftsinprivateenabledbyincreasedinternationalcooperationincludingmobilisingfinance,optionsincludebetterassessmentofclimate-relatedrisksandenhancingaccesstoﬁnance,particularlyfordevelopingcountries,andinvestmentopportunitieswithinthefinancialsystem,reducingvulnerableregions,sectorsandgroupsandaligningﬁnanceﬂowssectoralandregionalmismatchesbetweenavailablecapitalandforclimateactiontobeconsistentwithambitionlevelsandfundinginvestmentneeds,improvingtherisk-returnprofilesofclimateneeds(highconﬁdence).Whileagreedprocessesandgoals,suchasinvestments,anddevelopinginstitutionalcapacitiesandlocalthoseintheUNFCCC,KyotoProtocolandParisAgreement,arehelpingcapitalmarkets.Macroeconomicbarriersinclude,amongstothers,(Section2.2.1),internationalﬁnancial,technologyandcapacitybuildingindebtednessandeconomicvulnerabilityofdevelopingregions.supporttodevelopingcountrieswillenablegreaterimplementation(highconﬁdence){WGIISPMC.5.4;WGIIISPME.4.2,WGIIISPME.5,andmoreambitiousactions(mediumconﬁdence).ByintegratingWGIIISPME.5.2,WGIIISPME.5.3}equityandclimatejustice,nationalandinternationalpoliciescanhelptofacilitateshiftingdevelopmentpathwaystowardssustainability,Scalingupﬁnancialﬂowsrequiresclearsignallingfromespeciallybymobilisingandenhancingaccesstoﬁnanceforvulnerablegovernmentsandtheinternationalcommunity(highconﬁdence).regions,sectorsandcommunities(highconﬁdence).InternationalTrackedﬁnancialﬂowsfallshortofthelevelsneededforcooperationandcoordination,includingcombinedpolicypackages,adaptationandtoachievemitigationgoalsacrossallsectorsandmaybeparticularlyimportantforsustainabilitytransitionsinemissions-regions(highconﬁdence).Thesegapscreatemanyopportunitiesintensiveandhighlytradedbasicmaterialsindustriesthatareexposedandthechallengeofclosinggapsislargestindevelopingtointernationalcompetition(highconﬁdence).Thelargemajorityofcountries(highconﬁdence).Thisincludesastrongeralignmentofemissionmodellingstudiesassumesigniﬁcantinternationalcooperationpublicﬁnance,loweringrealandperceivedregulatory,costandmarkettosecureﬁnancialﬂowsandaddressinequalityandpovertyissuesinbarriers,andhigherlevelsofpublicﬁnancetolowertherisksassociatedpathwayslimitingglobalwarming.Therearelargevariationsinthewithlow-emissioninvestments.Up-frontrisksdetereconomicallymodelledeffectsofmitigationonGDPacrossregions,dependingsoundlowcarbonprojects,anddevelopinglocalcapitalmarketsareannotablyoneconomicstructure,regionalemissionsreductions,policyoption.Investors,ﬁnancialintermediaries,centralbanksandﬁnancialdesignandlevelofinternationalcooperation(highconfidence).regulatorscanshiftthesystemicunderpricingofclimate-relatedrisks.ADelayedglobalcooperationincreasespolicycostsacrossregionsrobustlabellingofbondsandtransparencyisneededtoattractsavers.(highconfidence).{WGIISPMD.2,WGIISPMD.3.1,WGIISPMD.5.2;(highconﬁdence){WGIISPMC.5.4;WGIIISPMB.5.4,WGIIISPME.4,WGIIISPMD.3.4,WGIIISPMC5.4,WGIIISPMC.12.2,WGIIISPME.6,WGIIISPME.5.4,WGIII15.2,WGIII15.6.1,WGIII15.6.2,WGIII15.6.7}WGIIISPME.6.1,WGIIIE.5.4,WGIIITS.4.2,WGIIITS.6.2;SR1.5SPMD.6.3,SR1.5SPMD.7,SR1.5SPMD.7.3}Thelargestclimateﬁnancegapsandopportunitiesareindevelopingcountries(highconﬁdence).AcceleratedsupportThetransboundarynatureofmanyclimatechangerisks(e.g.,forfromdevelopedcountriesandmultilateralinstitutionsisacriticalsupplychains,marketsandnaturalresourceﬂowsinfood,ﬁsheries,enablertoenhancemitigationandadaptationactionandcanaddressenergyandwater,andpotentialforconﬂict)increasestheneedinequitiesinﬁnance,includingitscosts,termsandconditions,andforclimate-informedtransboundarymanagement,cooperation,economicvulnerabilitytoclimatechange.Scaled-uppublicgrantsforresponsesandsolutionsthroughmulti-nationalorregionalmitigationandadaptationfundingforvulnerableregions,e.g.,inSub-governanceprocesses(highconﬁdence).MultilateralgovernanceSaharanAfrica,wouldbecost-effectiveandhavehighsocialreturnseffortscanhelpreconcilecontestedinterests,worldviewsandvaluesintermsofaccesstobasicenergy.Optionsforscalingupmitigationabouthowtoaddressclimatechange.Internationalenvironmentandandadaptationindevelopingregionsinclude:increasedlevelsofpublicsectoralagreements,andinitiativesinsomecases,mayhelptostimulateﬁnanceandpubliclymobilisedprivateﬁnanceﬂowsfromdevelopedlowGHGinvestmentandreduceemissions(suchasozonedepletion,todevelopingcountriesinthecontextoftheUSD100billion-a-yeartransboundaryairpollutionandatmosphericemissionsofmercury).goaloftheParisAgreement;increasetheuseofpublicguaranteesImprovementstonationalandinternationalgovernancestructurestoreducerisksandleverageprivateﬂowsatlowercost;localcapitalwouldfurtherenablethedecarbonisationofshippingandaviationmarketsdevelopment;andbuildinggreatertrustininternationalthroughdeploymentoflow-emissionsfuels,forexamplethroughcooperationprocesses.Acoordinatedefforttomakethepost-stricterefficiencyandcarbonintensitystandards.Transnationalpandemicrecoverysustainableoverthelongtermthroughincreasedpartnershipscanalsostimulatepolicydevelopment,low-emissionsﬂowsofﬁnancingoverthisdecadecanaccelerateclimateaction,technologydiffusion,emissionreductionsandadaptation,bylinkingsub-includingindevelopingregionsfacinghighdebtcosts,debtdistressnationalandotheractors,includingcities,regions,non-governmentalandmacroeconomicuncertainty.(highconﬁdence){WGIISPMC.5.2,organisationsandprivatesectorentities,andbyenhancinginteractionsWGIISPMC.5.4,WGIISPMC.6.5,WGIISPMD.2,WGIITS.D.10.2;betweenstateandnon-stateactors,thoughuncertaintiesremainoverWGIIISPME.5,WGIIISPME.5.3,WGIIITS.6.4,WGIIIBoxTS.1,WGIII15.2,theircosts,feasibility,andeffectiveness.InternationalenvironmentalWGIII15.6}andsectoralagreements,institutions,andinitiativesarehelping,andinsomecasesmayhelp,tostimulatelowGHGemissionsinvestmentandreduceemissions.(mediumconﬁdence){WGIISPMB.5.3,WGIISPMC.5.6,WGIITS.E.5.4,WGIITS.E.5.5;WGIIISPMC.8.4,WGIIISPME.6.3,WGIIISPME.6.4,WGIIISPME.6.4,WGIIITS.5.3}112Near-TermResponsesinaChangingClimateHighermitigationinvestmentﬂowsrequiredforallsectorsandregionstolimitglobalwarmingActualyearlyﬂowscomparedtoaverageannualneedsinbillionsUSD(2015)peryearMultiplication050010001500200025003000factorsBysectorLowerUpperrangerangeEnergyefﬁciencyx2x7Transportx7x7Electricityx2x5Agriculture,forestryandotherlandusex10x31Bytypeofeconomyx4x7DevelopingcountriesDevelopedcountriesx3x5Byregionx2x4EasternAsiaNorthAmericax3x6EuropeSouthernAsiax2x4LatinAmericaandCaribbeanAustralia,JapanandNewZealandx7x14EasternEuropeandWest-CentralAsiaAfricax4x8South-EastAsiaandPaciﬁcMiddleEastx3x70x7x15x5x12x6x12x14x2850010001500200025003000Yearlymitigationinvestment2017IEAdatameanMultiplicationfactorsindicatethex-foldincreasebetweenyearlySection4ﬂows(USD2015/yr)in:2017–2020mitigationﬂowstoaverageyearlymitigationinvestmentneeds.2018AverageﬂowsGlobally,currentmitigationﬁnancialﬂowsareafactorofthreeAnnualmitigationinvestmenttosixbelowtheaveragelevelsupto2030.2019needs(averageduntil2030)2020Figure4.6:Breakdownofaveragemitigationinvestmentﬂowsandinvestmentneedsuntil2030(USDbillion).Mitigationinvestmentﬂowsandinvestmentneedsbysector(energyefﬁciency,transport,electricity,andagriculture,forestryandotherlanduse),bytypeofeconomy,andbyregion(seeWGIIIAnnexIIPartISection1fortheclassiﬁcationschemesforcountriesandareas).Thebluebarsdisplaydataonmitigationinvestmentﬂowsforfouryears:2017,2018,2019and2020bysectorandbytypeofeconomy.Fortheregionalbreakdown,theannualaveragemitigationinvestmentﬂowsfor2017–2019areshown.Thegreybarsshowtheminimumandmaximumlevelofglobalannualmitigationinvestmentneedsintheassessedscenarios.Thishasbeenaverageduntil2030.Themultiplicationfactorsshowtheratioofglobalaverageearlymitigationinvestmentneeds(averageduntil2030)andcurrentyearlymitigationﬂows(averagedfor2017/18–2020).Thelowermultiplicationfactorreferstothelowerendoftherangeofinvestmentneeds.Theuppermultiplicationfactorreferstotheupperrangeofinvestmentneeds.Giventhemultiplesourcesandlackofharmonisedmethodologies,thedatacanbeconsideredonlyifindicativeofthesizeandpatternofinvestmentneeds.{WGIIIFigureTS.25,WGIII15.3,WGIII15.4,WGIII15.5,WGIIITable15.2,WGIIITable15.3,WGIIITable15.4}4.8.3.TechnologyInnovation,Adoption,DiffusionandInternationalcooperationoninnovationsystemsandtechnologyTransferdevelopmentandtransfer,accompaniedbycapacitybuilding,knowledgesharing,andtechnicalandﬁnancialsupportcanEnhancingtechnologyinnovationsystemscanprovideacceleratetheglobaldiffusionofmitigationtechnologies,opportunitiestoloweremissionsgrowthandcreatesocialandpracticesandpoliciesandalignthesewithotherdevelopmentenvironmentalco-beneﬁts.Policypackagestailoredtonationalobjectives(highconﬁdence).Choicearchitecturecanhelpend-userscontextsandtechnologicalcharacteristicshavebeeneffectiveadopttechnologyandlow-GHG-intensiveoptions(highconﬁdence).insupportinglow-emissioninnovationandtechnologydiffusion.Adoptionoflow-emissiontechnologieslagsinmostdevelopingcountries,Supportforsuccessfullow-carbontechnologicalinnovationparticularlyleastdevelopedones,dueinparttoweakerenablingincludespublicpoliciessuchastrainingandR&D,complementedbyconditions,includinglimitedﬁnance,technologydevelopmentandregulatoryandmarket-basedinstrumentsthatcreateincentivesandtransfer,andcapacitybuilding(mediumconﬁdence).{WGIIISPMB.4.2,marketopportunitiessuchasapplianceperformancestandardsandWGIIISPME.6.2,WGIIISPMC.10.4,WGIII16.5}buildingcodes.(highconfidence){WGIIISPMB.4,WGIIISPMB.4.4,WGIIISPME.4.3,WGIIISPME4.4}113Section4Internationalcooperationoninnovationworksbestwhentailoredtoimpactinglabourmarketsandworseninginequalitiesbetweenandbeneﬁcialforlocalvaluechains,whenpartnerscollaborateonanandwithincountries(mediumconﬁdence).Digitalisationrequiresequalfooting,andwhencapacitybuildingisanintegralpartoftheappropriategovernanceandpoliciesinordertoenhancemitigationeffort(mediumconﬁdence).{WGIIISPME.4.4,WGIIISPME.6.2}potential(highconﬁdence).Effectivepolicypackagescanhelptorealisesynergies,avoidtrade-offsand/orreducereboundeffects:Technologicalinnovationcanhavetrade-offsthatincludethesemightincludeamixofefﬁciencytargets,performancestandards,externalitiessuchasnewandgreaterenvironmentalimpactsandinformationprovision,carbonpricing,ﬁnanceandtechnicalassistancesocialinequalities;reboundeffectsleadingtolowernetemission(highconﬁdence).{WGIIISPMB.4.2,WGIIISPMB.4.3,WGIIISPME.4.4,reductionsorevenemissionincreases;andoverdependenceonWGIIITS6.5,WGIIICross-ChapterBox11onDigitalizationinChapter16}foreignknowledgeandproviders(highconﬁdence).AppropriatelydesignedpoliciesandgovernancehavehelpedaddressdistributionalTechnologytransfertoexpanduseofdigitaltechnologiesforlanduseimpactsandreboundeffects(highconﬁdence).Forexample,digitalmonitoring,sustainablelandmanagement,andimprovedagriculturaltechnologiescanpromotelargeincreasesinenergyefﬁciencythroughproductivitysupportsreducedemissionsfromdeforestationandlandcoordinationandaneconomicshifttoservices(highconﬁdence).usechangewhilealsoimprovingGHGaccountingandstandardisationHowever,societaldigitalizationcaninducegreaterconsumptionof(mediumconﬁdence).{SRCCLSPMC.2.1,SRCCLSPMD.1.2,SRCCLSPMD.1.4,goodsandenergyandincreasedelectronicwasteaswellasnegativelySRCCL7.4.4,SRCCL7.4.6}4.9IntegrationofNear-TermActionsAcrossSectorsandSystemsThefeasibility,effectivenessandbeneﬁtsofmitigationandadaptationactionsareincreasedwhenmulti-sectoralsolutionsareundertakenthatcutacrosssystems.Whensuchoptionsarecombinedwithbroadersustainabledevelopmentobjectives,theycanyieldgreaterbeneﬁtsforhumanwell-being,socialequityandjustice,andecosystemandplanetaryhealth.(highconﬁdence)SectioSnec4tion1Climateresilientdevelopmentstrategiesthattreatclimate,open,ensurebeneﬁtsinmultiplesectorsandsystemsandsuggesttheecosystemsandbiodiversity,andhumansocietyaspartsofanavailablesolutionspaceforadaptingtolong-termclimatechangeintegratedsystemarethemosteffective(highconﬁdence).Human(veryhighconﬁdence).Trade-offsintermsofemployment,waterandecosystemvulnerabilityareinterdependent(highconﬁdence).use,land-usecompetitionandbiodiversity,aswellasaccessto,Climateresilientdevelopmentisenabledwhendecision-makingprocessesandtheaffordabilityof,energy,food,andwatercanbeavoidedandactionsareintegratedacrosssectors(veryhighconﬁdence).bywell-implementedland-basedmitigationoptions,especiallythoseSynergieswithandprogresstowardstheSustainableDevelopmentthatdonotthreatenexistingsustainablelandusesandlandrights,withGoalsenhanceprospectsforclimateresilientdevelopment.Choicesandframeworksforintegratedpolicyimplementation(highconﬁdence).actionsthattreathumansandecosystemsasanintegratedsystembuild{WGIISPMC.2,WGIISPMC.4.4;WGIIISPMC.6.3,WGIIISPMC.6,ondiverseknowledgeaboutclimaterisk,equitable,justandinclusiveWGIIISPMC.7.2,WGIIISPMC.8.5,WGIIISPMD.1.2,WGIIISPMD.1.5,approaches,andecosystemstewardship.{WGIISPMB.2,WGIIFigureWGIIISPME.1.2}SPM.5,WGIISPMD.2,WGIISPMD2.1,WGIISPM2.2,WGIISPMD4,WGIISPMD4.1,WGIISPMD4.2,WGIISPMD5.2,WGIIFigureSPM.5}Mitigationandadaptationwhenimplementedtogether,andcombinedwithbroadersustainabledevelopmentobjectives,Approachesthataligngoalsandactionsacrosssectorsprovidewouldyieldmultiplebeneﬁtsforhumanwell-beingaswellasopportunitiesformultipleandlarge-scalebeneﬁtsandavoidedecosystemandplanetaryhealth(highconﬁdence).Therangeofdamagesinthenearterm.Suchmeasurescanalsoachievesuchpositiveinteractionsissigniﬁcantinthelandscapeofnear-termgreaterbeneﬁtsthroughcascadingeffectsacrosssectorsclimatepoliciesacrossregions,sectorsandsystems.Forexample,(mediumconﬁdence).Forexample,thefeasibilityofusinglandforAFOLUmitigationactionsinland-usechangeandforestry,whenbothagricultureandcentralisedsolarproductioncanincreasewhensustainablyimplemented,canprovidelarge-scaleGHGemissionsuchoptionsarecombined(highconﬁdence).Similarly,integratedreductionsandremovalsthatsimultaneouslybeneﬁtbiodiversity,foodtransportandenergyinfrastructureplanningandoperationscansecurity,woodsupplyandotherecosystemservicesbutcannotfullytogetherreducetheenvironmental,social,andeconomicimpactsofcompensatefordelayedmitigationactioninothersectors.Adaptationdecarbonisingthetransportandenergysectors(highconﬁdence).Themeasuresinland,oceanandecosystemssimilarlycanhavewidespreadimplementationofpackagesofmultiplecity-scalemitigationstrategiesbeneﬁtsforfoodsecurity,nutrition,healthandwell-being,ecosystemscanhavecascadingeffectsacrosssectorsandreduceGHGemissionsandbiodiversity.Equally,urbansystemsarecritical,interconnectedbothwithinandoutsideacity’sadministrativeboundaries(veryhighsitesforclimateresilientdevelopment;urbanpoliciesthatimplementconﬁdence).Integrateddesignapproachestotheconstructionandmultipleinterventionscanyieldadaptationormitigationgainswithretroﬁtofbuildingsprovideincreasingexamplesofzeroenergyorequityandhumanwell-being.Integratedpolicypackagescanimprovezerocarbonbuildingsinseveralregions.Tominimisemaladaptation,theabilitytointegrateconsiderationsofequity,genderequalitymulti-sectoral,multi-actorandinclusiveplanningwithﬂexibleandjustice.Coordinatedcross-sectoralpoliciesandplanningcanpathwaysencourageslow-regretandtimelyactionsthatkeepoptionsmaximisesynergiesandavoidorreducetrade-offsbetweenmitigation114Near-TermResponsesinaChangingClimateandadaptation.Effectiveactioninalloftheaboveareaswillrequirenear-termpoliticalcommitmentandfollow-through,socialcooperation,ﬁnance,andmoreintegratedcross-sectoralpoliciesandsupportandactions.(highconﬁdence).{WGIISPMC.1,WGIISPMC.2,WGIISPMC.2,WGIISPMC.5,WGIISPMD.2,WGIISPMD.3.2,WGIISPMD.3.3,WGIIFigureSPM.4;WGIIISPMC.6.3,WGIIISPMC.8.2,WGIIISPMC.9,WGIIISPMC.9.1,WGIIISPMC.9.2,WGIIISPMD.2,WGIIISPMD.2.4,WGIIISPMD.3.2,WGIIISPME.1,WGIIISPME.2.4,WGIIIFigureSPM.8,WGIIITS.7,WGIIITSFigureTS.29:SRCCLES7.4.8,SRCCLSPMB.6}(3.4,4.4)Section4115

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