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THE LONG-TERM STRATEGY

OF THE UNITED STATES

Pathways to Net-Zero Greenhouse Gas Emissions by 2050

NOVEMBER 

The Long-Term Strategy of the United States: Pathways

to Net-Zero Greenhouse Gas Emissions by 2050.

Published by the United States Department of State

and the United States Executive Oce of the President,

Washington DC. November 2021.

CONTENTS

01 Preface

03 Executive Summary

10 Chapter 1:

An Integrated U.S. Climate Strategy

to Reach Net-Zero Emissions by 2050

13 Chapter 2:

The Decisive Decade to 2030

17 Chapter 3:

Pathways to 2050 Net-Zero

Emissions in the United States

25 Chapter 4:

Transforming the Energy System

Through 2050

35 Chapter 5:

Reducing Non-CO2 Emissions

Through 2050

45 Chapter 6:

Removing Carbon Through 2050

and Beyond

50 Chapter 7:

Benefits of Climate Action

Through 2050

55 Chapter 8:

Accelerating Global Climate Progress

57 References

THE LONG-TERM STRATEGY OF THE UNITED STATES

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THELONG-TERMSTRATEGYOFTHEUNITEDSTATESPathwaystoNet-ZeroGreenhouseGasEmissionsby2050NOVEMBER2021TheLong-TermStrategyoftheUnitedStates:PathwaystoNet-ZeroGreenhouseGasEmissionsby2050.PublishedbytheUnitedStatesDepartmentofStateandtheUnitedStatesExecutiveOfficeofthePresident,WashingtonDC.November2021.CONTENTS01Preface03ExecutiveSummary10Chapter1:AnIntegratedU.S.ClimateStrategytoReachNet-ZeroEmissionsby205013Chapter2:TheDecisiveDecadeto203017Chapter3:Pathwaysto2050Net-ZeroEmissionsintheUnitedStates25Chapter4:TransformingtheEnergySystemThrough205035Chapter5:ReducingNon-CO2EmissionsThrough205045Chapter6:RemovingCarbonThrough2050andBeyond50Chapter7:BenefitsofClimateActionThrough205055Chapter8:AcceleratingGlobalClimateProgress57ReferencesTHELONG-TERMSTRATEGYOFTHEUNITEDSTATESIntheUnitedStatesandaroundtheworld,wearealreadyfeelingtheimpactsofachangingclimate.Hereathome,in2021alonewehaveseenhistoricdroughtsandwildfiresintheWest,unprecedentedstormsandfloodingintheSoutheast,andrecordheatwavesacrossthecountry.Weseethesamedevastatingevidencearoundtheworldinplaceslikethefire-ravagedAmazon,theswelteringurbancenterofDelhi,andtheshrinkingcoastlinesofislandnationslikeTuvalu.Thescienceisclear:weareheadedtowardclimatedisasterunlessweachievenet-zeroglobalemissionsbymidcentury.Wealsoknowthiscrisispresentsvastopportunitiestobuildabettereconomy,createmillionsofgood-payingjobs,cleanourwatersandair,andensureallAmericanscanlivehealthier,safer,strongerlives.Thetimeisnowfordecisiveaction,andtheUnitedStatesisboldlytacklingtheclimatechallenge.In2021,werejoinedtheParisAgreement,setanambitiousNationallyDeterminedContributiontoreducenetgreenhousegasemissionsby50-52%in2030,launchedtheGlobalMethanePledge,andhaveundertakenadditionalconcreteactionstoadvanceclimateactiondomesticallyandinternationally.Theseinvestmentsarecriticaltoimmediatelyaccelerateouremissionsreductions.This2021Long-TermStrategyrepresentsthenextstep:itlaysouthowtheUnitedStatescanreachitsultimategoalofnet-zeroemissionsnolaterthan2050.Achievingnet-zeroemissionsishowwe—andourfellownationsaroundtheglobe—willkeepa1.5°Climitonglobaltemperaturerisewithinreachandpreventunacceptableclimatechangeimpactsandrisks.TheLong-TermStrategyshowsthatreachingnet-zeronolaterthan2050willrequireactionsspanningeverysectoroftheeconomy.Therearemanypotentialpathwaystogetthere,andallpath-waysstartwithdeliveringonour2030NationallyDeterminedContribution.ThiswillputtheUnitedStatesfirmlyontracktoreachnet-zeroby2050andsupporttheoverarchingvisionofbuildingamoresustainable,resilient,andequitableeconomy.Thebenefitsofanet-zerofuturewillnotonlybefeltbyfuturegenerations.Mobilizingtoachievenet-zerowillalsodeliverstrongnetbenefitsforallAmericansstartingtoday.DrivingdowngreenhousegaseswillPREFACE1THELONG-TERMSTRATEGYOFTHEUNITEDSTATES2THELONG-TERMSTRATEGYOFTHEUNITEDSTATEScreatehigh-qualityjobs,improvepublichealthineverycommunity,andspurinvestmentsthatmodernizetheAmericaneconomywhilereducingcostsandrisksfromclimatechange.Reducingairpollutionthroughcleanenergywillalonehelpavoid300,000prematuredeathsintheUnitedStates—alleviatingtheseandothersevereimpactsthatalsofalldisproportionatelyoncommunitiesofcolorandlow-incomecommunities.Investmentsinemergingcleanindustrieswillenhanceourcompetitivenessandpropelsustainedeconomicgrowth.ModernizingtheAmericaneconomytoachievenet-zerocanfundamentallyimprovethewaywelive,creatingmoreconnected,moreaccessible,andhealthiercommunities.Thatdoesnotmeanitwillhappenquicklyorwithouthardwork.Therewillbemanychallengesonourpathtonet-zerothatwillrequireustomarshalallouringenuityanddedication.Butitcan,andmust,bedone.Andevenasweinvestathome,thenewtechnologiesandinvestmentsoutlinedinthisstrategywillalsohelpscaleuplow-cost,carbon-freesolutionsfortheworld.Wecancreateahealthy,vibrant,andabundantworldforourchildren.Thisplanisourpromisetothem—anditisonewemustkeep.JOHNKERRYSPECIALPRESIDENTIALENVOYFORCLIMATEGINAMCCARTHYNATIONALCLIMATEADVISOR3THELONG-TERMSTRATEGYOFTHEUNITEDSTATESAddressingtheclimatecrisisrequiresimmediateandsustainedinvestmenttoeliminatenetglobalgreenhousegasemissionsbymid-century—andthispresentsatransformationalopportunityfortheUnitedStatesandtheworld.Investinginthecleantechnologies,infrastructure,workforce,andsystemsofthefuturecreatesanunprecedentedopportunitytoimprovequalityoflifeandcreatevibrant,sustainable,resilient,andequitableeconomies.Asweundertakethisglobaltransformation,theUnitedStatesandothermajoreconomiesmustactquicklytokeepasaferclimatewithinreach.AcrosstheUnitedStatesandaroundtheworld,climatechangeisalreadyharmingcommunities—particularlythemostvulnerablethatareleastequippedtocope,rebuild,andadapt.Wildfires,storms,floods,extremeheat,andotherclimate-fueledimpactsarecausingdeaths,injuries,degradedhealth,economichardship,anddamagetotheearth’secosystems—allfromwarmingofonlyroughly1.0oC.Failuretoimmediatelycurtailemissionswillcondemntheworldtonearlytriplethatlevelofwarming,unleashingfarmorefrequentandsevereclimateimpactsandfarmoreextremedownsiderisks.ThemostrecentreportfromtheIntergovernmentalPanelonClimateChange(IPCC)vividlyillustrates,withrobustscientificconfidence,theneedtolimitwarmingto1.5oC,orascloseaspossibletothatcrucialbenchmark,toavoidthesesevereclimateimpacts.Achievingthistargetwillrequirecuttingglobalgreenhousegas(GHG)emissionsbyatleast40%below1990levelsby2030,reachingglobalnet-zeroGHGemissionsby2050orsoonafter,andmovingtonetnegativeemissionsthereafter[1].Tomeettheseglobalmilestones,wemustretooltheglobalenergyeconomy,transformagriculturalsystems,haltandreversedeforestation,anddecisivelyaddressnon-carbondioxideemissions—focusingparticularattentiononmethane(CH4),whichaccountsroughly0.5oCofthecurrentobservednetwarmingof1.0oC.1Wemustalsopursuenegativeemissionsthroughrobustandverifiablenature-basedandtechnologicalcarbondioxideremoval.INLIGHTOFTHISURGENCY,THEUNITEDSTATESHASSETAGOALOFNET-ZEROGREENHOUSEGASEMISSIONSBYNOLATERTHAN2050.1Greenhousegasemissionsintotalhavecontributed150%oftheobservedwarmingof1.0⁰C,butemissionsofcoolingaerosolshavecounteractedsomeofthatwarming.EXECUTIVESUMMARY4THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTHISU.S.NET-ZERO2050GOALISAMBITIOUS.ItputstheUnitedStatesaheadofthetrajectoryrequiredtokeep1.5°Cwithinreachthroughthreedecadesofinvestmentincleanpower,electrificationoftransportationandbuildings,industrialtransformation,reductionsinmethaneandotherpotentnon-carbondioxideclimatepollutants,andbolsteringofournaturalandworkinglands.DELIVERINGONOUR2030NATIONALLYDETERMINEDCONTRIBUTION(NDC)WILLPUTTHEUNITEDSTATESFIRMLYONTRACKTONET-ZERO.TheUnitedStateshascommittedtoanambitiousandachievablegoaltoreducenetGHGemissions50-52%below2005levelsin2030.2Thisisthedecisivedecadetodeliveronasetofnewpolicies[2]toaccelerateexistingemissionsreductiontrends—forexample,expandingrapidlythedeploymentofnewtechnologieslikeelectricvehiclesandheatpumps,andbuildingtheinfrastructureforkeysystemslikeournationalpowergrid.Thesetypesofnear-termactionswillputusonfirmfootingtomeetour2050goal(asillustratedbyFigureES-1).2TheUnitedStatesformallycommunicatedthis2030targetinitsNationallyDeterminedContributiononApril21,2021.FigureES-1:UnitedStateshistoricemissionsandprojectedemissionsunderthe2050goalfornet-zero.ThisfigureshowsthehistoricaltrajectoryofU.S.netGHGemissionsfrom1990to2019,theprojectedpathwaytothe2030NDCof50-52%below2005levels,andthe2050net-zerogoal.TheUnitedStateshasalsosetagoalfor100%cleanelectricityin2035;thatgoalisnotaneconomy-wideemissionsgoalsodoesnotappearinthisfigure,butitwillbecriticaltosupportdecarbonizationintheelectricitysector,whichwillinturnhelptheU.S.reachits2030and2050goalsincombinationwithbroadelectrificationofenduses.17%BELOW2005LEVELSIN202026-28%BELOW2005LEVELSIN202550-52%BELOW2005LEVELSIN2030Net-ZeroIN2050012345670%-10%-20%-30%-40%-50%-60%-70%-80%-90%-100%1990199520002005201020152020202520302035204020452050Emissions(GigatonsCO2e)PercentBelow2005HISTORICEMISSIONS17%BELOW2005LEVELSIN2020U.S.PROJECTEDEMISSIONSUNDER2025TARGETU.S.PROJECTEDEMISSIONSUNDER2030TARGETU.S.PROJECTEDEMISSIONSUNDER2050GOAL5THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTHISREPORTPRESENTSTHE2021LONG-TERMSTRATEGY(LTS)OFTHEUNITEDSTATES.Itillustratesmultiplepathwaystoanet-zeroeconomynolaterthan2050[3][4][5].Itconfirmshowactionstakennowandthroughthisdecadearecriticaltomakethesenet-zeropathwayspossible.Thereportdrawsfromadiverseanalyticaltoolkit,3includingaglobalintegratedassessmentmodelcoveringallGHGsandeconomicsectors,anationalcarbondioxide(CO2)modelwithhighenergysectorresolution,modelsoftheU.S.landsector,andarichsetofnon-governmentalliterature.PursuanttoArticle4.19oftheParisAgreement,thisreportalsoservestocommunicateourLong-TermStrategytotheinternationalcommunity.MOBILIZINGTOACHIEVENET-ZEROWILLDELIVERSTRONGNETBENEFITSFORALLAMERICANS.DrivingdownGHGswillspurinvestmentsthatmodernizetheAmericaneconomy,addressthedistributionalinequitiesofenvironmentalpollutionandclimatevulnerability,improvepublichealthineverycommunity,andreducetheseverecostsandrisksfromclimatechange.Benefitsinclude:•PUBLICHEALTH.Reducingairpollutionthroughcleanenergywillavoid85,000–300,000prematuredeaths,andhealthandclimatedamagesof$150–$250billionthrough2030.Itwillavoid$1–3trillionindamagesthrough2050intheUnitedStatesalone.Thesemeasureswillalsohelpalleviatethepollutionburdensdisproportionatelybornebycommunitiesofcolor,low-incomecommunities,andindigenouscommunities.•ECONOMICGROWTH.Investmentsinnascentcleanindustrieswillenhancecompetitivenessandpropelsustainedgrowth.TheUnitedStatescanleadincrucialcleantechnologieslikebatteries,electricvehicles,andheatpumps,withoutsacrificingcriticalworkerprotections.3ThecoreanalysespresentedinthisreportaresharedwiththeU.S.NationalClimateStrategyandtheU.S.NationalCommunicationandBiennialReporttotheUNFrameworkConventiononClimateChange(UNFCCC).•REDUCEDCONFLICT.Drought,floods,andotherdisastersfueledbyclimatechangehavecausedlarge-scaledisplacementsandconflict.TheU.S.DepartmentofDefenserecognizesclimatechangeasavital,globallydestabilizingnationalsecuritythreat[6].EarlyactionbytheUnitedStateswillencouragefasterclimateactionglobally,includingbydrivingdownthecostsofcarbon-freetechnologies.Theseactionswillultimatelysupportsecurityandstabilityworldwide.•QUALITYOFLIFE.ModernizingtheAmericaneconomytoachievenet-zerocanfundamentallyimprovethewaywelive.Measureslikehigh-speedrailandtransit-orienteddevelopmentnotonlyreduceemissionsbutalsocreatemoreconnected,accessible,andhealthiercommunities.THE2050NET-ZEROEMISSIONSGOALISACHIEVABLE.TheUnitedStatescandelivernet-zeroemissionsacrossallsectorsandGHGsthroughmultiplepathways,butallviableroutestonet-zeroinvolvefivekeytransformations:1.DECARBONIZEELECTRICITY.ElectricitydeliversdiverseservicestoallsectorsoftheAmericaneconomy.Thetransitiontoacleanelectricitysystemhasbeenacceleratinginrecentyears—drivenbyplummetingcostsforsolarandwindtechnologies,federalandsubnationalpolicies,andconsumerdemand.Buildingonthissuccess,theUnitedStateshassetagoalof100%cleanelectricityby2035,acrucialfoundationfornet-zeroemissionsnolaterthan2050.2.ELECTRIFYENDUSESANDSWITCHTOOTHERCLEANFUELS.Wecanaffordablyandefficientlyelectrifymostoftheeconomy,fromcarstobuildingsandindustrialprocesses.Inareaswhereelectrificationpresentstechnologychallenges—forinstanceaviation,shipping,andsomeindustrialprocesses—wecanprioritizecleanfuelslikecarbon-freehydrogenandsustainablebiofuels.6THELONG-TERMSTRATEGYOFTHEUNITEDSTATES3.CUTENERGYWASTE.Movingtocleanersourcesofenergyismadefaster,cheaper,andeasierwhenexistingandnewtechnologiesuselessenergytoprovidethesameorbetterservice.Thiscanbeachievedthroughdiverse,provenapproaches,rangingfrommoreefficientappliancesandtheintegrationofefficiencyintonewandexistingbuildings,tosustainablemanufacturingprocesses.4.REDUCEMETHANEANDOTHERNON-CO2EMISSIONS.Non-CO2gasessuchasmethane,hydrofluorocarbons(HFCs),nitrousoxide(N2O),andothers,contributesignificantlytowarming—withmethanealonecontributingfullyhalfofcurrentnetglobalwarmingof1.0°C.Therearemanyprofitableorlow-costoptionstoreducenon-CO2sources,suchasimplementingmethaneleakdetectionandrepairforoilandgassystemsandshiftingfromHFCstoclimate-friendlyworkingfluidsincoolingequipment.TheU.S.iscommittedtotakingcomprehensiveandimmediateactionstoreducemethanedomestically.AndthroughtheGlobalMethanePledge,theU.S.andpartnersseektoreduceglobalmethaneemissionsbyatleast30%by2030,whichwouldeliminateover0.2°Cofwarmingby2050.TheU.S.willalsoprioritizeresearchanddevelopmenttounlocktheinnovationneededfordeepemissionsreductionsbeyondcurrentlyavailabletechnologies.5.SCALEUPCO2REMOVAL.Inthethreedecadesto2050,ouremissionsfromenergyproductioncanbebroughtclosetozero,butcertainemissionssuchasnon-CO2fromagriculturewillbedifficulttodecarbonizecompletelybymid-century.Reachingnet-zeroemissionswillthereforerequireremovingcarbondioxidefromtheatmosphere,usingprocessesandtechnologiesthatarerigorouslyevaluatedandvalidated.Thisrequiresscalinguplandcarbonsinksaswellasengineeredstrategies.FigureES-2illustrateshowthefivekeytransformationscancombineindifferentpathwaystoachievenet-zeroemissionsby2050.Theexactpathwaywilldependonhowquicklychangeoccursacrossdifferentsectors.Nevertheless,somebroadpatternsareclear.Forexample,energysystemtransformationscontributeroughly4.5gigatonsofCO2equivalentperyear(GtCO2e/yr.)ofoverallemissionsreductions,orabout70%ofoverallreductions.Theseenergyemissionsreductionsaredeliveredbycuttingenergywaste,decarbonizingelectricity,andtransitioningenergysourcesincludingthroughfuelswitchingandelectrification.Addressingnon-CO2gases,includingmethane,nitrousoxide,andfluorinatedgases,reducesanother1Gtofannualemissions.EnhancinglandsinksandscalingupCO2removaltechnologiesalsodeliverabout1Gtofnegativeemissions.Whilethesefiguresareahelpfulroughguide,theexactcontributionfromeachareavariesbetweenpathways(asshowninFigureES-2).TheeventualU.S.pathwaytonet-zeroemissionswilldependontheevolutionoftechnologies,thespecificsofpolicyandregulatorypackages,andfactorssuchaseconomicgrowth,sociodemographicshifts,andmarketpricesforcommoditiesandfuelsacrossthenextthreedecades.ACHIEVINGNET-ZEROBYNOLATERTHAN2050REQUIRESSUSTAINED,COORDINATEDACTIONSPANNINGFOURSTRATEGICPILLARS:1.FEDERALLEADERSHIP.Federalleadershipiscriticaltoreduceemissions50-52%below2005levelsin2030andsetuptheeconomytoachievenet-zeroemissionsby2050.Thiscouldincludeinvestmentsandincentivesthatsupportthedeploymentofcleantechnologiesinallsectors,policiestoenhanceandsupportournaturalandworkinglands,partnershipstocatalyzemarkettransformation,improvedintegrationofclimateintofinancialmarketsincludingenhancedclimateriskdisclosure,andthepromulgationandenforcementofnewandexistingregulationsrootedinlaw.7THELONG-TERMSTRATEGYOFTHEUNITEDSTATES2.INNOVATION.Indrivingthedeploymentofcurrentlycompetitivetechnologiesasrapidlyaspossible,federalpolicieswillservetofurtherreducecoststhrougheconomiesofscaleandlearning-by-doing.Inaddition,newtechnologieswillbenecessarytodrivedeeperreductionsinthelate2020’sthrough2050.Federally-supportedresearch,development,demonstration,anddeploymentcanbetheprimemover—alongwithfederal,subnational,andprivatesectorprocurement—tocarrynewcarbon-freetechnologiesandprocessesfromthelabtoU.S.factoriestothemarket.Researchanddevelopmenttodaywilllaythetechnologyfoundationnecessarytomaximizeeconomicbenefitsfromthepost-2030transformationtonet-zero.3.NON-FEDERALLEADERSHIP.TheU.S.federalsystemisbasedonthenationalgovernmentsharingpowerwithelectedgovernmentsatsubnationallevels.Inoursystem,policyauthoritiesrelatedtoeconomicactivity,energy,transportation,landuse,andmorearesharedwithTribalgovernments,states,cities,counties,andothers.U.S.climateactionthereforenecessarilyspansalllevelsofgovernment.RecenttrendsdemonstratethesignificantimpactsthatthesesubnationalpoliciescanhaveontheoverallU.S.emissionstrajectory,inwaysthatcomplementnationalpoliciesandcanprovideabroaderbaseforlearningandforacceleratingaction.FigureES-2:EmissionsReductionsPathwaystoAchieve2050Net-ZeroEmissionsintheUnitedStates.Achievingnet-zeroacrosstheentireU.S.economyrequirescontributionsfromallsectors,including:efficiency,cleanpower,andelectrification;reducingmethaneandothernon-CO2gases;andenhancingnaturalandtechnologicalCO2removal.Theleftsideofthefigureshowsarepresentativepathwaywithhighlevelsofactionacrossallsectorstoachievenet-zeroby2050.Therightsideshowsasetofalternativepathwaysdependingonvariationsinuncertainfactorssuchastrendsinrelativetechnologycostsandthestrengthofthelandsectorcarbonsink.ALTERNATEPATHWAYSTO2050NET-ZEROREPRESENTATIVEPATHWAYTO2050NET-ZERO8THELONG-TERMSTRATEGYOFTHEUNITEDSTATESIFOTHERMAJORECONOMIESADOPTSIMILARAMBITION,WECANKEEP1.5°CWITHINREACH.TheU.S.currentlyemits11%ofannualglobalGHGs(secondtoChina,whichemits27%oftheglobaltotal).Cuttingouremissionsatleastinhalfby2030andeliminatingouremissionsby2050willthereforemakeanimportantdirectcontributiontokeepingasafer1.5°Cfuturewithinreach.Theseeffortswillalsospurcostreductionsforcleantechnologiesthroughscaleandlearning-by-doing.Moreimportantly,U.S.climateleadershiphasalreadyhelpedpropelothermajoreconomiestoadopt2030NDCsthatarealignedwiththeimperativetocutglobalemissionsatleast40%by2030toimproveourchancesoflimitingglobalwarmingtolessthan1.5°C.AttheLeaders’SummitonClimateinAprilof2021,PresidentBidenannouncedourambitiousNDC,joinedbyCanadianandJapaneseleaderswhoalsosetstrongnew2030targets.TheEuropeanUnion(EU)andUnitedKingdom(UK)hadalreadysetstrongtargetsand,sincetheSummit,others,includingtheRepublicofKoreaandSouthAfrica,havecomeforwardwithNDCsthatachievethepaceofreductionsthatwouldbeneededgloballytokeep1.5°Cwithinreach.Thesecountriesrepresentwelloverhalfoftheglobaleconomy,butfurtheractionbyothermajoreconomieswillbenecessarytoensurethe1.5°Ctargetismet.4.ALL-OF-SOCIETYACTION.Thelong-termtransformationstogetto2050net-zeroemissionswillrequiretheUnitedStatestobringallitsgreateststrengthstobear,includinginnovation,creativity,anddiversity.Already,manynon-governmentalorganizationsareactingambitiouslytoaddressclimatechangewithintheirownoperationsorsupporttheoveralltransitionoftheU.S.economy.Evenmorebroad-basedengagementonresearch,education,andimplementationthroughouruniversities,culturalinstitutions,investors,businesses,andothernon-governmentalorganizationswillberequiredtoreachour2050goal.IMPLEMENTATIONISUNDERWAY.Thesefourprinciplesformthecoreofourstrategytoachieveour2030NDCand100%cleanelectricityby2035.Wearemovingrapidly,rootedinactionsfromacrossthefederalgovernmentandothergovernmentalandnon-governmentalactors.TheseactionsandpoliciesarepartofourLong-TermStrategyandaredescribedinaforthcomingcompanionreporttothisdocument,TheU.S.NationalClimateStrategy(NCS)[2].TheNCSdescribesanoverarchingapproachthatcoversallaspectsoffederalaction,whichwillalsosupportbroadernon-federalandall-of-societyefforts.BoththeNCSandthisLong-TermStrategyhavebeeninformedbyarobuststakeholderengagementprocess.Theseactionsprovidethenear-termimplementationmomentumtoachievethe2030NDC,2035100%cleanelectricitygoal,andthe2050net-zerogoal.Globally,thisisthemomentforalltheworld’smajoreconomiestoacttorapidlyreduceemissionstomeetambitious2030NDCtargetsandtodevelopandcommunicatestrategiestoachieveambitious2050net-zerogoals.FOURCOMPONENTSOFU.S.REPORTINGONCLIMATEACTIONSANDSTRATEGY1.TheU.S.NationalClimateStrategydetailshowwewilldeliverourU.S.NDCfor2030[2].ItfocusesontheimmediatepoliciesandactionsthatwillputAmericaontracktoreduceemissionsby50-52%below2005levelsin2030andputinplacethetechnologyandinfrastructurenecessarytoachievenet-zeroemissionsnolaterthan2050.2.TheLong-TermStrategyoftheUnitedStatestoReachNet-ZeroEmissionsby2050(thisreport),pursuanttoArticle4.19oftheParisAgreement,showshowthesecurrentandnear-termpoliciesandotheractionsacrossthecountry,asdescribedintheNCS,deliverapathwaythroughthe2030sand2040storeachour2050net-zerogoal.AsacontributionundertheParisAgreement,itispartofaprocessthatservestosupportenhancedglobalactionandambition.CommunicatingactionsandprogresstowardclimategoalsisacriticalcomponentoftransparencytosupportglobalambitionundertheParisAgreement.TheUnitedStatesiscommittedtotheseprinciplesand,accordingly,isissuingfourreportsdetailingcomplementaryaspectsofourcurrentclimateactivitiesandplannedstrategy.Thesamekeyassumptionsandmethodologiesaresharedintheanalyticsthatinformallfourreports.EachreportservesadifferentroleincommunicatingtheoverallsituationandstrategyoftheUnitedStates,andtherearedetailsineachthatarenotreproducedacrossallreports.Togethertheypresentavisionforourclimatestrategyandemissionspathways.3.TheU.S.NationalCommunicationandBiennialReportprovidesdetailedinformationonexistingpoliciesandmeasuresacrossallareasofU.S.climateactionasofDecember2020[7].ItfulfillsourobligationsforreportingandtransparencyundertheUNFrameworkConventiononClimateChange(UNFCCC)andfitsintoabroaderinternationalreportingframeworkinwhichothercountriesalsoparticipate.4.TheU.S.AdaptationCommunicationprovidesforward-lookingprioritiesforacceleratingadaptationandbuildingresiliencedomesticallyandabroad[8].Itoutlinesdomesticclimateimpactsandvulnerabilities,progressonadaptation,lessonslearned,andimmediatepoliciesandotherapproachesthatwillincreaseadaptivecapacity,enhanceresilience,andreducevulnerabilitytoclimatechange.ItcomplementsandbuildsuponresilienceandadaptationactionslaidoutintheNationalClimateStrategyandU.S.NationalCommunicationandBiennialReport.THELONG-TERMSTRATEGYOFTHEUNITEDSTATES910THELONG-TERMSTRATEGYOFTHEUNITEDSTATESClimatechangealreadyinflictsseriousdamageontheUnitedStatesandtheworld,particularlythemostvulnerablethatareleastequippedtoadapt—andthescienceisclearthat,withoutfasterglobalaction,theseimpactswillbecomemuchmorefrequentandsevere.TworecentreportsfromtheIntergovernmentalPanelonClimateChange[1][9]affirmwithrobustscientificconfidencetheneedtokeepwarmingunder1.5°Ctoreducethegreatestglobalrisksandavoidsignificant,wide-ranging,andsevereimpacts.Tokeep1.5°Cwithinreach,theUnitedStateshasagoalofachievingnet-zeroemissionseconomy-widebynolaterthan2050[3][4][5].TheParisAgreementestablishesaframeworktorapidlyincreaseglobalambitiontoholdwarmingwellbelow2°Cwhilepursuingeffortstolimitwarmingto1.5°C.Thisframeworkincludesnationallydeterminedcontributions(NDCs)—commitmentsthattargetnear-termemissionsreductions,reviewprogress,andseektoextendandstrengthentheirNDCsinregular5-yearcycles.TheParisAgreementalsospecificallycallsonallcountriesto“formulateandcommunicatetheirlong-term,lowGHGemissiondevelopmentstrategies.”SuchLong-TermStrategiessupportglobalambitionbyencouragingcountriestounderstandtheiroptionsandsettheirownlonger-termemissionsreductiongoals[10].Indevelopingandcommunicatingthesestrategies[11],countriescanforeseeandaddresschallengessuchasslowinfrastructureturnoverortheneedforjusttransitionsfromfossilfuelsandotherhigh-emissiontechnologies.Developingandsharingpubliclythesenear-andlong-termstrategieshelpselucidateandmanagepathdependenciesandbetterconnectshort-termandlong-termobjectives.Accordingly,thisprocesscanbothguidenationalactionandencouragegreaterglobalambitionovertime.TheUnitedStatesissimultaneouslypursuingmultipleclimatemitigationgoals(Figure1).EachgoalservesasanimportantmilestonetowardrapidlyreducingourGHGemissionstonet-zero.Whilethisreportemphasizesthelongerperiodof2021-2050,theoverallU.S.strategyintegratesactionsforbothnear-termand2050goals:•The2030NDCof50-52%reductionsbelow2005levels,coveringallsectorsandallgases•Thegoalfor100%carbonpollution-freeelectricityby2035•Thegoalfornet-zeroemissionsnolaterthan2050.CHAPTER1:ANINTEGRATEDU.S.CLIMATESTRATEGYTOREACHNET-ZEROEMISSIONSBY205011THELONG-TERMSTRATEGYOFTHEUNITEDSTATESThesenear-termactionsarebeingimplementedrapidly,rootedinpoliciesfromacrossthefederalgovernmentandothergovernmentalandnon-governmentalactorsintheUnitedStates.Theseactionsandpoliciesaredescribedindetailinacompaniontothisdocument,TheU.S.NationalClimateStrategy(NCS)[2].TheNCSlaysoutanoverarchingpolicyapproachbeingundertakentodaythatcoversallaspectsoffederalaction,insupportofall-of-societyefforts.Theseactionsprovidethenear-termimplementingmomentumtoachievethe2030NDC,meetthe2035100%cleanelectricitygoal,andputtheU.S.inastrongpositiontotaketheadditionalactionsnecessarytoachievenet-zeroby2050.Theinformationonnear-termimplementationintheNCSshouldthereforebeviewedasintegraltotheU.S.Long-TermStrategy.Accordingly,althoughthisreportfocusesontheperiodfrom2021to2050,itreferstotheNCSforfurtherdescriptionsofnear-termimplementationoflong-termgoals.TheBidenAdministrationconsulteddiversestakeholderstoinformtheoverallU.S.climatestrategythatisreflectedintheU.S.Long-TermStrategy(LTS)report.ThisconsultationcoveredawiderangeofstakeholdersfrommajorunionsthatworkonbehalfofmillionsofAmericanworkers,togroupsrepresentingtensofmillionsofadvocates,fencelinecommunities,andyoungAmericans.Engagementtodevelopourstrategyalsoincludedgroupsrepresentingscientists;hundredsofgovernmentalleaderslikegovernors,mayors,andNativeAmericanleaders;hundredsofbusinesses;hundredsofschoolsandinstitutionsofhighereducation;aswellaswithmanyspecializedresearchersfocusedonquestionsofpollutionFigure1:UnitedStateshistoricemissionsandprojectedemissionsunderthe2050goalfornet-zero.ThisfigureshowshistoricalU.S.GHGemissionsfrom1990to2019,theprojectedpathwaytothe2030NDCof50-52%below2005levels,andthe2050net-zerogoal.TheUnitedStateshasalsosetagoalfor100%cleanelectricityin2035.Thatgoalisnotaneconomy-wideemissionsgoalsodoesnotappearinthisfigure,butitwillbecriticaltosupportdecarbonizationintheelectricitysector,whichwillinturnhelptheU.S.reachits2030and2050goals.17%BELOW2005LEVELSIN202026-28%BELOW2005LEVELSIN202550-52%BELOW2005LEVELSIN2030Net-ZeroIN2050012345670%-10%-20%-30%-40%-50%-60%-70%-80%-90%-100%1990199520002005201020152020202520302035204020452050Emissions(GigatonsCO2e)PercentBelow2005HISTORICEMISSIONS17%BELOW2005LEVELSIN2020U.S.PROJECTEDEMISSIONSUNDER2025TARGETU.S.PROJECTEDEMISSIONSUNDER2030TARGETU.S.PROJECTEDEMISSIONSUNDER2050GOAL12THELONG-TERMSTRATEGYOFTHEUNITEDSTATESreduction.NCSreportreferencedabovehassimilarlybeendevelopedthroughextensiveconsultationsofdiversestakeholders,whoseperspectivesandinputhaveinformedtheoverallclimatestrategythatisreflectedinthisLTSreport.TheUnitedStatespresenteditsfirstLong-TermStrategyreportin2016[12],focusedonreducingnetGHGs80-90%below2005levelsby2050.In2021,theUnitedStatesputforwardanew,ambitiousgoalofnet-zeroemissionsnolaterthan2050.Thisreportpresentsanupdated2021Long-TermStrategyoftheUnitedStatesthatdefinesmultiplepathwaysfortheAmericaneconomytoachievenet-zeroemissionsby2050.Itincludesanalysisofwhattransformationalpathwaystonet-zerocouldlooklikeovertimeforemissionsindifferentsectorsandfordifferentGHGs.Thereportdrawsfromadiverseanalyticaltoolkit,4integratinginsightsfromaglobalintegratedassessmentmodelcoveringallgreenhousesandeconomicsectors,anationalCO2modelwithhighresolutionontheelectricitysector,modelsofU.S.landsector,andmore.Theanalysispresentedherewasbasedonaninteragencyeffortandisgroundedinabroaderbodyofexistingscholarshipandliterature4Thesecoreanalysesinthisreportaresharedwithtwocompanionvolumes,theU.S.NationalClimateStrategyandtheU.S.NationalCommunicationandBiennialReporttotheUNFCCC.forhowtounderstandbothnear-andlong-termhigh-ambitionemissionspathwaysinthenationalandglobalcontext.Whiletheanalysespresentedhereprovidenewandoriginalinsights,theyalsodrawfromandreferencethisbroaderbodyofwork.Thisreportisorganizedasfollows.Chapter2focusesonthedecisivedecadefromnowto2030andhighlightstheU.S.prioritieswhichwillbothdramaticallyreduceGHGemissionsandlaythefoundationforachievingnet-zeroemissionsnolaterthan2050.Chapter3givesanoverviewoftheeconomy-wideemissionspathwaysto2050.Chapter4describespathwaysforenergy-relatedCO2emissionsreductionacrosselectricity,transportation,buildings,andindustry.Chapter5presentsthekeyopportunitiesformethaneandothernon-CO2emissionsreductions,includingintheenergy,waste,agriculture,andindustrialsectors.Chapter6focusesonCO2removalsthroughlandsandtechnologiesforcarbondioxideremoval.Chapter7presentsavisionofthemanybenefitsthatwillbecreatedonthepathtoanet-zeroemissionseconomy,includingtransformativeimprovementsinpublichealth,avoidedclimatedamages,enhancedclimatesecurity,andjobgrowth.Finally,Chapter8concludeswithavisionoftheU.S.acceleratingglobalclimateprogresswithambitiousdomesticclimateaction.THEU.S.2050NET-ZEROGOALTheUnitedStateshassetagoalofnet-zeroemissionsbynolaterthan2050.ThegoalincludesallmajorGHGs(CO2,CH4,N2O,HFCs,PFCs,SF6,NF3)andiseconomy-wide.Thegoalisonanetbasis,includingbothsourcesofemissionsandremovals.Itdoesnotincludeemissionsfrominternationalaviationorinternationalshipping.Atthistime,theUnitedStatesdoesnotexpecttouseinternationalmarketmechanismstowardachievementofthisnet-zerogoal.ProgresstowardthegoalwillbeassessedandtheU.S.LTSmaybeupdated,asappropriate.13THELONG-TERMSTRATEGYOFTHEUNITEDSTATESPuttingtheUnitedStatesonapathtonet-zeroemissionseconomy-widenolaterthan2050requirestakingtransformativeactionsthisdecadeandachievingnear-termmilestonesinlinewiththisgoal.ThisiswhytheUnitedStatessetaneconomy-widetargetofreducingitsnetGHGemissionsby50-52%below2005levelsin2030(Figure2).TheUnitedStateswillalsosoonreleaseacomplementaryreport,TheU.S.NationalClimateStrategy(NCS)[2],followingthis2021Long-TermStrategy,toprovideadditionaldetailonthestepstheUnitedStatesistakingtoachieveour2030target—andindoingso,toputtheUnitedStatesonatracktoachieveits2050net-zerogoal.This2030commitmentanchorstheU.S.approachduringthisdecadetobuildasustainable,resilient,andequitableeconomybyrapidlydeployingwidelyavailablelow-carbontechnologiesandinvestingintheinfrastructure,innovation,andworkforcethatisthefoundationofthiseconomictransformation.Thisdecadewillbedecisive—andthebenefitsofachievingour2030goalwillbesignificant.Transitioningtoacleanenergyeconomywillcreatebetween500,000andonemillionnetnewjobsacrossthecountrythisdecade[13][14].Moreover,reducingairpollutionthroughtheseeffortswillavoid85,000–300,000prematuredeaths[14][15].Thistransitionwillrequireamulti-prongedapproachinvolvingtheprivatesector,sub-nationalgovernments,andfederalgovernmenttogeneratenewregulations,directinvestment,andprogramsatalllevelsofgovernment.Near-termactionstoacceleratethistransitionarebeingimplementedrapidly,rootedinactionsfromacrossthefederalgovernmentandothergovernmentalandnon-governmentalactorsintheUnitedStates.TheseactionsandpoliciesaredescribedindetailintheNCSreport,whichlaysoutanoverarchingpolicyapproachbeingundertakentoday—informedbyongoingengagementofdiversestakeholders—thatcoversallaspectsoffederalaction,insupportofall-of-societyefforts.Theseactionsprovidethenear-termimplementingmomentumtoachievethe2030NDC,2035100%cleanelectricitygoal,andthe2050net-zerogoal.Asummaryoftheseelementsisprovidedbelow.CHAPTER2:THEDECISIVEDECADETO203014THELONG-TERMSTRATEGYOFTHEUNITEDSTATES2.1ELECTRICITYFastandcost-effectiveemission-reducinginvestmentsareavailableintheelectricpowersector,whichiscurrentlythesecond-largestproducerofemissionsintheUnitedStates.ThatiswhytheUnitedStatessetagoaltoreacha100%carbonpollution-freeelectricitysystemby2035,whichcanbeachievedthroughmultiplecost-effectivetechnologyandinvestmentpathways.Infact,thistransitionhasalreadybeenacceleratinginrecentyears—drivenbyplummetingcostsofkeytechnologieslikesolar,onshorewind,offshorewind,andbatteries,aswellasenhancedpoliciesandincreasedconsumerdemandforclean,reliable,andaffordablepower.Furtheraccelerationofcleanenergydeploymentcanbecatalyzedthroughprovidingincentivesandstandardstoreducepollutionfrompowerplants;investingintechnologiestoincreasetheflexibilityoftheelectricitysystem,suchastransmission,energyefficiency,energystorage,smartandconnectedbuildings,andnon-emittingfuels;andleveragingcarboncaptureandstorage(CCS)andnuclear.Significantdeploymentofenergyefficiencyreducesoveralldemandandcanlowerpeakload,reducinggridcapitalcostsandmakinginvestmentsincarbon-freepowergenerationgofurther.Research,development,demonstration,anddeploymentofnewsoftwareandhardwaresolutionswillfurthersupportthetransformationtoacarbonpollution-free,resilient,reliable,andaffordableelectricitysystem.Figure2:UnitedStateshistoricemissionsandprojectedemissionsunderthe2030NDCtarget.ThisfigureshowsthehistoricaltrajectoryofU.S.GHGemissionsandthepathwaytothe2030GHGreductiontargets.The2030NDCtargetisambitious,andpoliciesandmeasureshaveputtheAmericaneconomyonadecliningemissionstrendconsistentwiththesegoals.The2030targetsputtheUnitedStatesonafastertrackthanastraight-linepathtonet-zeroin2050wouldrequire.17%BELOW2005LEVELSIN202026-28%BELOW2005LEVELSIN202550-52%BELOW2005LEVELSIN2030012345670%-10%-20%-30%-40%-50%-60%-70%-80%-90%-100%199019952000200520102015202020252030Emissions(GigatonsCO2e)PercentBelow2005HISTORICEMISSIONS17%BELOW2005LEVELSIN2020U.S.PROJECTEDEMISSIONSUNDER2025TARGETU.S.PROJECTEDEMISSIONSUNDER2030TARGET15THELONG-TERMSTRATEGYOFTHEUNITEDSTATES2.2TRANSPORTATIONVehicleshavebecomethelargestemissionssourceintheUnitedStates—drivenbyfossilfueluseinlight-dutycars,trucks,andSUVs,followedbymedium-andheavy-dutytrucks,buses,air,off-roadvehicles,rail,andshipping.TherearemanyopportunitiestoreduceGHGemissionsfromtransportationwhilealsosavingmoneyforhouseholdsandbusinesses,improvingenvironmentalqualityandhealthincommunities,andprovidingmorechoicesformovingpeopleandgoods.Atitscore,thisrequireselectrifyingmostvehiclestorunonever-cleanerelectricityandshiftingtolow-carbonorcarbon-freebiofuelsandhydrogeninapplicationslikelong-distanceshippingandaviation.Tosupportthisoutcome,theUnitedStatessetagoalforhalfofallnewlight-dutycarssoldin2030tobezero-emissionvehicles,toproduce3billiongallonsofsustainableaviationfuelby2030,andtoacceleratedeploymentandreducecostsineverymodeoftransportation.Thiswilloccurthroughlowervehiclecosts;fueleconomyandemissionsstandardsinlight-,medium-andheavy-dutyvehicles;incentivesforzero-emissionvehiclesandcleanfuels;investmentinanewcharginginfrastructuretosupportmulti-unitdwellings,publiccharging,andlong-distancetravel;scalingupbiorefineries;comprehensiveinnovationinvestmentstoreducehydrogencosts;andinvestmentininfrastructurethatsupportsallmodesofcleantransportation—suchastransit,rail,biking,micromobility,andpedestrianoptions.Makingprogressthisdecaderequiresinvestingindomesticmanufacturingandreliablesupplychainsforcleanfuels,batteries,andvehicles.Inaddition,research,development,demonstration,anddeploymentofelectrificationandzero-orlow-carbonfuelsforaviationandshippingwillensurewehavethetechnologytocontinuereducingemissionsacrosstheentiretransportationsectorintheyearsleadingto2050.2.3BUILDINGSBuildingsandtheirenergy-consumingsystems—electricityusedandfossilfuelsburnedonsiteforheatingair,heatingwater,andcooking—havelonglifetimes.Therefore,thepriorityinthisdecadeistorapidlyimproveenergyefficiencyandincreasethesalesshareofcleanandefficientelectricappliances—includingheatpumpsforspaceconditioning,heatpumpwaterheaters,electricandinductionstoves,andelectricclothesdryers—whilealsoimprovingtheaffordabilityofenergyandtheequitableaccesstoefficientappliances,efficiencyretrofits,andcleandistributedenergyresourcesinbuildings.Thisincludesinvestmentinpublicbuildingssuchaspublichousing,governmentfacilities,schools,anduniversities.Researchanddemonstrationinvestmentsnowwillalsoadvancenewsolutionsforefficient,grid-interactive,andelectrifiedbuildings.Achieving100%cleanpowergenerationby2035willalsoeliminateupstreamemissionsfromelectricityandfacilitatecarbon-freeandefficientelectrificationofappliancesandequipmentinbuildings.Moreover,partnershipsliketheEnvironmentalProtectionAgency(EPA)ENERGYSTARandtheadvancementofbuildingenergycodesandappliancestandardswillensurethatbuildingenvelopes,electricappliances,andotherequipmentbecomeincreasinglyefficientovertime.Efficientelectricspaceheatingandcoolingandwaterheatingofferimportantopportunitiestoemploygrid-interactivedemandtolowerenergybillsforhouseholdsandbusinesseswhilemorecost-effectivelyutilizingcarbon-freeelectricity.2.4INDUSTRYTheindustrialsectoremitsGHGsthroughmultiplecomplexpathways.ThisincludesCO2emittedindirectlythroughelectricityanddirectlythroughon-sitefossilfuelcombustionandpowergeneration,aswellasemissionsofCO2andnon-CO2GHGsleakedfromon-siteuseoremittedthroughindustrialprocesses(suchascementproduction).Industrialdecarbonizationcanbedeliveredthroughenergyefficiency;industrialelectrification;low-carbonfuels,feedstock,andenergy16THELONG-TERMSTRATEGYOFTHEUNITEDSTATESsources;andindustrialCCS.Achievingcleanpowerby2035willeliminatetheemissionsfromgridpowerconsumedbyindustryandmakepossiblethecarbon-freeelectrificationofcertainindustrialprocessesthatarecurrentlydominatedbyfossilfueluse.Low-andmedium-temperatureprocessheatarecandidatesforindustrialelectrificationintheneartermthroughincreaseduseofindustrialheatpumps,electricboilers,orelectromagneticheatingprocesses.Additionaltechnologiesandprocessinnovationsarealsoneededtoaddressotherindustrialemissions,includinghigh-temperatureheatandprocessemissionsfromsteel,petrochemical,andcementproduction.FundamentallynewprocesseswillbeneededtoaddressthechemicalprocessemissionsassociatedwiththeproductionofthesecommoditymaterialsthathavelargeGHGemissionsfootprints.Energyefficiencymeasuresmakecarbon-freeelectricityandotherlow-carbonindustrialfuelsstretchasfaraspossibleandasearlyaspossible.TheUnitedStateswillalsoscalesupportforrelatedresearch,development,demonstration,commercialization,anddeploymentofzero-carbonindustrialinnovations.Thisincludesincentivesforcarboncaptureandnewsourcesofcleanhydrogen—producedfromrenewableenergy,nuclearenergy,orwaste—topowerindustrialfacilities.Todrivethemarketforthesesolutions,theUnitedStatesgovernmentwillalsouseitsprocurementpowertosupportearlymarketsfortheseverylow-andzero-carbonindustrialgoods.Additionally,monitoringandcontroltechnologiesareneededtopreventthereleasetotheatmosphereofnon-CO2GHGsfromindustrialoperations,includingmethane,fluorinatedgases,blackcarbon,andotherpotentshort-livedclimatepollutants.TheUnitedStateshasfinalizedregulationstophasedowntheuseoffluorinatedgasesconsistentwithourobligationsundertheKigaliAmendmenttotheMontrealProtocol.Addressingmethaneemissionswillalsorequiresettingstringentstandardsforoilandgasproductionandinvestinginpluggingleaksfromcoal,oil,andgasminesandwells.2.5AGRICULTURE,FORESTRY,ANDLANDUSEAmerica’svastlandsprovideopportunitiestobothreduceemissionsandsequestercarbon.Capitalizingontheseopportunitiesincludes:continuingtoexpandforestarea,extendingrotationlengths,protectingforestarea,integratingtreesintourbanareasandagriculture,scalingupclimate-smartagriculturalpracticessuchascovercrops,andemployingrotationalgrazingonouragriculturallands.Evenmoreleveragecanbederivedthroughprogramsandincentivestoimproveagriculturalproductivity;suchpracticesandtechnologiescanfreeuplandforotherusesaswellasreduceagriculturalmethaneandN2Oemissionsthrough,forexample,improvedmanuremanagementandimprovedcroplandnutrientmanagement.Enhancedinvestmentinforestprotectionandforestmanagement,alongwithscience-basedandsustainableeffortstoreducethescopeandintensityofcatastrophicwildfiresandtorestorefire-damagedforestland,arevitaltoprotectingandgrowingthelargestlandsink.Alongsidetheseefforts,theUnitedStateswillsupportnature-basedcoastalresilienceprojectsincludingpre-disasterplanningaswellaseffortstoincreasecarbonsequestrationinwaterwaysandoceansbypursuing“bluecarbon.”Finally,climate-smartpracticescanalsolowertheemissionsintensityofbiofuelsneededfordecarbonizingtransportation.Actionstakennowandthroughthisdecadewillensurewemaximizethepotentialofourlandsandwaterstosequestercarbontothegreatestextentpossibleby2050.Acrossthesesectors,theU.S.federalgovernmentisworkingwithTribalgovernments,states,andlocalitiestosupportrapiddeploymentofnewcarbon-pollution-freetechnologiesandfacilitieswhileensuringtheymeetrobustandrigorousstandardsforworkers,publicandenvironmentalsafety,andenvironmentaljustice.Accomplishingthegoalsthisdecadeandsettinguptheeconomyforfurtherreductionsafter2030alsorequiresinvestmentininnovationandU.S.manufacturingtolowerthecostofnewtechnologiesneededinthefuture,growthedomesticmanufacturingbaseandsupplychainsforthosetechnologies,andtraintheworkforceneeded.17THELONG-TERMSTRATEGYOFTHEUNITEDSTATESThedecisivedecadethrough2030iscentraltosettingtheUnitedStates—andtheworld—onapathwaythatkeepswarmingof1.5°Cwithinreach.Forallcountries,2030isanessentialwaypointthatispartofalongerpathtoreachglobalnet-zeroemissionsbymid-century.TheambitiouspoliciesandgoalsdescribedinChapter2willsettheUnitedStatesonapathwaytoachieveour2030target.Atthesametime,theseactionswillalsocatalyzethelonger-termchangesintheAmericanenergy,industrial,andlandsystemsrequiredtoachievenet-zeroby2050.Thischapterpresentstheresultsofacomprehensiveanalysisundertakentoassesspotentialpathwaystonet-zeroemissionsintheUnitedStatesbynolaterthan2050.Thesepathwaysareallgroundedinourstrategytoachieveour2030NDCandourgoalof100%carbonpollution-freeelectricityby2035.Thesetransitionpathwaysarenotonlyaffordable,but,becauseofthebenefitsfromreducedclimatechangeandimprovedpublichealth,theywillalsocreatewide-rangingbenefits(seeChapter7).Itwillrequireambitiousactionandinvestmentgroundedinintensiveengagementwithcommunities,workers,andbusinessestoensurethatthebenefitsofthetransitionareequitablydistributed—withafocusonthosecommunitiesthatremainoverburdenedandunderserved.3.1ASSESSINGMITIGATIONOPPORTUNITIESTOACHIEVENET-ZEROEMISSIONSAchievingrapidemissionsreductionsrequiresintegratingnear-termpolicydriverswithastrategytoassessandmanagelonger-termfactorslikecapitalstockturnoverandtechnologicalinnovation.Tothisend,thisLTSemploysdiverseanalyticalapproachestoprojecttheimpactofalternateassumptionsaboutpolicies,technologies,andotherdrivers.Theseaffordabroadunderstandingforwhatlong-termnet-zerotechnologytransformationswouldlooklikeglobally[16]aswellasprovidingroadmapsforhowtoaffectthosetransitionsrapidly[17].InlightoftheParisgoalstodevelopandcommunicatenationalemissionsreductionspathways,suchanalyticalapproacheshavealsobeenappliedtounderstandingspecificnationalcircumstancesandopportunities,includingthosewithintheUnitedStates.SomeoftheseU.S.-specificstudiesfocusonpolicyframeworkstodrivenear-termactionthatwouldsettheU.S.onapathwaytolonger-termnet-zeroor1.5°C-compatibleemissions[18][19][20].Inparallel,otherslookatthepotentialforintegratingall-of-societystrategiesthatincludediverselevelsofgovernmentandotheractors[21].CHAPTER3:PATHWAYSTO2050NET-ZEROEMISSIONSINTHEUNITEDSTATES18THELONG-TERMSTRATEGYOFTHEUNITEDSTATESOthershavefocusedonoveralllong-termtechnologicaltransformationsandassociatedemissionreductionstrategiesthatwouldbenecessaryforreductiontonet-zerointheU.S.by2050.Manyofthese2050studiesaddressemissionsreductionacrosstheentireeconomyandforallgases[14][22][23];othersfocusonspecificareasorsectorssuchasenergy,electricity[13][24],transportation[25],ormanufacturing[26].ThisresearchhasadvancedthinkingaboutwhatispossiblewithintheUnitedStatesandwhatrobuststrategiestoreach2050net-zerocouldlooklike.Theassessmentandanalyticalapproachespresentedhereareoriginaltothisreportbutalsorecognizethemanyinsightsofferedinthiswiderliterature,includingbutnotlimitedtostudiesspecificallyon2050net-zeropathways.Insightsfromthisliteratureareconsistentinwhattheytellusaboutthecriticalelementssupportingthelong-termemissionsreductiontrajectoryfortheUnitedStates.Thistrajectoryrestsontheintegrationoffivecomplementarytechnologicaltransformations:1.DECARBONIZEELECTRICITY.ElectricitydeliversdiverseservicestoallsectorsoftheAmericaneconomy.Thetransitiontoacleanelectricitysystemhasbeenacceleratinginrecentyears—drivenbyplummetingcostsforsolarandwindtechnologies,federalandsubnationalpolicies,andconsumerdemand.Buildingonthissuccess,theUnitedStateshassetagoalof100%cleanelectricityby2035,acrucialfoundationfornet-zeroby2050.2.ELECTRIFYENDUSESANDSWITCHTOOTHERCLEANFUELS.Wecanaffordablyandefficientlyelectrifymostoftheeconomy—fromcarstobuildingsandindustrialprocesses.Inareaswhereelectrificationpresentstechnologychallenges—forinstanceaviation,shipping,andsomeindustrialprocesses—wecanprioritizecleanfuelslikecarbon-freehydrogenandsustainablebiofuels.3.CUTENERGYWASTE.Movingtocleanersourcesofenergyismadefaster,cheaper,andeasierwhenexistingandnewtechnologiesuselessenergytoprovidethesameorbetterservice.Thiscanbeachievedthroughdiverse,provenapproaches,rangingfromnewandmoreefficientappliancesandtheintegrationofefficiencyintonewandexistingbuildings,tosustainablealternatemanufacturingprocessesandtheintegrationofefficiencyintonewandexistingbuildings.4.REDUCEMETHANEANDOTHERNON-CO2EMISSIONS.Non-CO2gasessuchasmethane,HFCs,nitrousoxide,andotherscontributesignificantlytowarming,withmethanealonecontributingfullyhalfofcurrentnetglobalwarmingof1.0°C.Therearemanyprofitableorlow-costoptionstoreducenon-CO2sources,suchasimplementingmethaneleakdetectionandrepairforoilandgassystemsandshiftingfromHFCstoclimate-friendlyworkingfluidsincoolingequipment.TheU.S.iscommittedtotakingcomprehensiveandimmediateactionstoreducemethanedomestically.AndthroughtheGlobalMethanePledge,theU.S.andpartnersseektoreduceglobalmethaneemissionsbyatleast30%by2030,whichwouldeliminateover0.2°Cofwarmingby2050.TheU.S.willalsoprioritizeresearchanddevelopmenttounlocktheinnovationneededfordeepemissionsreductionsbeyondcurrentlyavailabletechnologies.5.SCALEUPCO2REMOVAL.Inthethreedecadesto2050,ouremissionsfromenergyproductioncanbebroughtclosetozerobutcertainemissionssuchasnon-CO2fromagriculturewillbedifficulttodecarbonizecompletelybymid-century.Reachingnet-zeroemissionswillthereforerequireremovingcarbondioxidefromtheatmosphere,usingprocessesandtechnologiesthatarerigorouslyevaluatedandvalidated.Thisrequiresscalinguplandcarbonsinksaswellasengineeredstrategies.Therearemanyplausiblepathwaysthrough2050toachievinganet-zeroemissionseconomy.However,developmentsinthesesectorsovertimeareinterdependent.Forexample,widespreadadoptioninleadingenergyefficiencypracticesinbuildingscouldsignificantlyimpactoverallelectricitydemand,reducingtheamountofnewcleanenergyinstallations19THELONG-TERMSTRATEGYOFTHEUNITEDSTATESrequired.Theinsightthatsectorsareinterdependentdemonstratestheimportanceofpolicyandincentivestorealizethebenefitsofdecarbonizationacrosstheeconomy.Recentdevelopmentsinenergy,manufacturing,andinformationtechnologyhavemadeswiftandsubstantialreductionspossible.Well-designedpoliciescanhelptoensurerapidandaffordableeconomy-widedecarbonization.Forexample,acceleratedshiftingtocarbon-freepowermakesend-useelectrificationanevenmoreeffectivestrategytodrivedownemissions.Inaddition,policiescanmaximizethebenefitsofdecarbonizationandensurethatunderservedcommunitiesbenefitequitablyfromthetransitiontoacleanenergysystem.Forexample,inclusiveinvestmentprogramstoscaleupfinancingforefficientelectrichomeupgradescanhelpleveltheplayingfieldforunderservedhouseholdsandensureeffectiveconsumerprotections.3.2CURRENTU.S.GHGEMISSIONSTRENDSIN2021NetU.S.GHGemissionspeakedin2007[27]aftergrowingthroughmuchofthepreviouscentury,drivenmainlybycombustionoffossilfuelstomeetgrowingdemandforenergyservices.Sincetheirpeak,netU.S.GHGemissionshavedeclined,drivenbyacombinationofforces.Federalpolicyhasplayedacrucialrole,includingthroughsustainedresearchanddevelopmentinvestmentswhichpropelledaninitialshiftfromcoaltogaspowerandthesimultaneousandnowdominantgrowthofrenewables;incentivesforrenewablesandzero-emissionvehicles;andsector-specificregulationssuchasemissionsstandardsforpowerplants,fueleconomystandards,andapplianceefficiencystandards.Tribalgovernments,U.S.states,cities,counties,andothernon-federalactorshaveplayedasimilarlycrucialroleacrossallsectorsoftheeconomy.Moreover,thisfederalandsubnationalinvestmentandpolicyhaspropelledavirtuouscycleoftechnologycostreductionsinducingevenlargermarketsforkeycarbon-freetechnologieswhich,inturn,drivesfurthercostreductionsthroughscaleandlearning.3.3.ANALYSISOFPOTENTIALU.S.TRAJECTORIESTONET-ZEROEMISSIONSBY2050ThenewanalysispresentedhereoffersinsightsintowhattheoverallemissionsprofilefortheUnitedStatescouldlooklikebetweennowand2050underasetofalternateassumptionsabouttheevolutionoftechnologicalcosts,economicgrowth,andotherdriversto2050.Weusetwoeconomy-widemodels(GCAMandOP-NEMS),arangeofsensitivityscenarios,supplementalmodelsforkeysectors,andcomparisonstothegrowingliteratureonpathwaystonet-zeroemissions.Thisprovidestransparencyonwhatthepossiblepathwaysto2050net-zeromightlooklike,andhowthosedifferentpathwayswouldaffecttheevolutionofspecificsectorsandratesofdeploymentforspecifictechnologies.Theassessmentpresentedinthischapterreflectsmodeloutputsthataresubjecttoseveraltypesofuncertainty.ThegoalofshowingtheseoutputsistoillustratetheevolutionoftheU.S.economyandresultingemissionsovertime.Whilethetechnologyassumptionsandpolicygoalsforthedecadeto2030arelargelyunderstood,thereisincreasinguncertaintyafter2030onhowanyindividualtechnologyorsectorwillevolve.Weshowseveraldifferentpathwaysbasedonalternateassumptions.Thesesensitivitiesillustratearangeofcredibleandplausiblepathwaystonet-zeroby2050.3.3.1DESCRIPTIONSOFTHEMODELSGlobalChangeAssessmentModel(GCAM)TheLTSscenarioswereproducedintheGlobalChangeAnalysisModel(GCAM)bythePacificNorthwestNationalLaboratory.TheGlobalChangeAnalysisModel(GCAM)isanintegratedassessmentmodelcoveringallmajorGHGsandallsectorsoftheeconomy,linkingtheworld'senergy,agriculture,andlandusesystemswithaclimatemodel.Itisusedtoexploretheinteractionsofemissions-reducinginvestmentsandactivitiesacrosstheU.S.andglobaleconomy.Themodelisdesignedtoassessclimatechangepoliciesand20THELONG-TERMSTRATEGYOFTHEUNITEDSTATEStechnologystrategiesfortheglobeoverlongtimescales.GCAMrunsin5-yeartimestepsfrom2005to2100andincludes32geopoliticalregionsintheenergyandeconomymoduleand384landregionsintheagricultureandlandusemodule.ThemodeltracksemissionsandatmosphericconcentrationsofGHGs(CO2andnon-CO2),carbonaceousaerosols,sulfurdioxide,andreactivegasesandprovidesestimatesoftheassociatedclimateimpacts,suchasglobalmeantemperatureriseandsealevelrise.GCAMcanincorporateemissionspricingandemissionconstraintsinconjunctionwiththenumeroustechnologyoptionsincludingsolar,wind,nuclear,andcarboncaptureandsequestration.Themodelhasbeenexercisedextensivelytoexploretheeffectoftechnologyandpolicyonclimatechangeandthecostofmitigatingclimatechange.GCAMisacommunitymodelprimarilydevelopedandmaintainedattheJointGlobalChangeResearchInstitute,apartnershipbetweenPacificNorthwestNationalLaboratory(PNNL)andtheUniversityofMaryland[28].OfficeofPolicy–NationalEnergyModelingSystem(OP-NEMS)TheLTSscenarioswereconstructedusingaversionoftheNationalEnergyModelingSystem(NEMS)developedbytheU.S.DepartmentofEnergy(DOE)OfficeofPolicy(OP-NEMS).NEMSisanintegratedenergy-economymodelingsystemfortheUnitedStatesthatprojectstheproduction,imports,conversion,andconsumptionofenergy,subjecttoassumptionsonmacroeconomicandfinancialfactors,worldenergymarkets,resourceavailabilityandcosts,costandperformancecharacteristicsofenergytechnologies,anddemographics.TheversionofNEMSusedinthisreporthasbeenrunbyOnLocation,Inc.,withmodelingapproachdeterminedwithinputfromtheDOEOfficeofPolicyandotherDOEtechnologyoffices.BecauseOP-NEMSprojectsonlyCO2emissionsrelatedtotheenergysector,externalassumptionswereprovidedregardingnon-CO2GHGsandlanduse,land-usechange,andforestry.OP-NEMSincludesenhancementsforcleanhydrogen,sustainablebiofuels,andindustrialcarboncapture,transport,andstorage[29].GlobalTimberModel(GTM)TheGlobalTimberModel(GTM)isadynamicintertemporaloptimizationeconomicmodelthatdeterminestimberharvests,timberinvestments,andlanduseoptimallyovertimeunderassumedfuturemarket,policy,andenvironmentalconditions.Thismodel’sapproachprovidesasimulationofharvesting,planting,andmanagementintensitydecisionsthatlandownersmightundertakeinresponsetotimberandcarbonmarketdemands,includingfuturepriceexpectations.Theseactivitiesincludeafforestationandlandusechange,forestmanagement,andforestproductsactivityinresponsetopoliciesandmarkets.Themodelgeneratesprojectionsusingdetailedbiophysicalandeconomicforestrydatafordifferentcountriesorregionsglobally,includingtheU.S.,China,Canada,Russia,andJapan.ItusedmacroeconomicdatafromAnnualEnergyOutlook2021fortheU.S.andglobalparametersfromSharedSocioeconomicPathway2(SSP2)[30].Themodelhasbeenwidelyusedtoassessforestdynamicsandcarbonoutcomesundervariousdemandandlandcarbonsinkscenarios,climateimpacts,andotherapplications[31][32].ForestryandAgricultureSectorOptimizationModelwithGreenhouseGases(FASOM-GHG)TheForestryandAgricultureSectorOptimizationModelwithGreenhouseGases(FASOM-GHG)modelisapartial-equilibriumdynamicintertemporal,price-endogenous,mathematicalprogrammingmodeldepictinglandtransfersandotherresourceallocationsbetweenandwithintheagriculturalandforestsectorsintheUnitedStates.FASOM-GHGincludesdetailedrepresentationsofagriculturalandforestproductmarkets,contemporaryforestinventories,intersectoralresourcecompetitionandlandchangecosts,andcostsofmitigationstrategies.TheresultsfromFASOM-GHGyieldadynamicsimulationofprices,production,management,consumption,GHGeffects,andotherenvironmentalandeconomicindicatorswithinthesetwosectors,underthechosenpolicyscenario.Theresultprovidesinsightintocross-sectoralinter-andintra-regionalresponsestopolicystimulireflecting21THELONG-TERMSTRATEGYOFTHEUNITEDSTATESthespatialheterogeneityinproductionofagricultureandforestryproductsacrosstheU.S.Todate,FASOM-GHGanditspredecessormodelshavebeenusedtoexaminetheeffectsofGHGmitigationpolicy,climatechangeimpacts,publictimberharvestpolicy,federalfarmprogrampolicy,bioenergyprospects,andpulpwoodproductionbyagricultureamongotherpoliciesandenvironmentalchanges[33].U.S.DepartmentofAgricultureForestServiceResourcesPlanningAct(RPA)modelingsystemTheLTSscenariosreflectresultsfromtheU.S.DepartmentofAgriculture(USDA)ForestServiceResourcesPlanningAct(RPA)modelingsystemwhichcomprisestheForestDynamicsmodel,integratedandharmonizedwiththeUSDAForestServiceRPALandUseChangeModelandtheForestResourceOutlookModel(FOROM)GlobalTradeModel[34].ThismodelingsystemsupportstheprojectionsofrenewableresourcesacrosstheU.S.intheUSDA2020ResourcesPlanningActAssessment.ProjectionsweredevelopedundercurrentclimateconditionswithoutCO2fertilizationandvaluesareaddedtoUSDAagriculturesoilsprojections.ThestorageandfluxofcarboninharvestedwoodproductsandsolidwastedisposalsiteswasprojectedusingFOROM.U.S.EPANon-CO2MarginalAbatementCost(MAC)ModelandReportTheU.S.EPANon-CO2MarginalAbatementCost(MAC)Modelisabottom-upengineeringcostmodelthatevaluatesthecostandabatementpotentialofnon-CO2mitigationtechnologies[35].Theassociatednon-CO2mitigationreport[36]providesacomprehensiveeconomicanalysisonthecostsoftechnologiestoreducenon-CO2gasesandthepotentialtoreducethembysector.3.3.2SCENARIODESCRIPTIONS&KEYASSUMPTIONSTheLTSanalysisincludesmultiplescenarioshighlightingdifferentpathwaysforachievingnet-zeroGHGemissionsby2050.Thefiguresinthischapterpresentresultsforarangeofassumptionsincludingthelandsink,technologies(i.e.,carbondioxideremoval,sector-specifictechnologies,andnon-CO2mitigationtechnologies),energyprices,population,andeconomicgrowth.TheadvancedLTSscenarioassumptionsaccountforcurrentlyavailableopportunitiesaswebuildbackfromthepandemicbyusingadvancedassumptionsforelectricity,transportation,industry,andbuildingsasmodeledinGCAMandOP-NEMS.Theunderlyingassumptionsinthescenariosetsareasfollows.Carbonremovallevelsrepresentthesumofthenetlandsink,derivedfrommodeledprojectionsoflanduse,landusechange,andforestry(LULUCF),andplausiblelevelsofcarbondioxideremovaltechnologyadoptionsuchasbiomassenergywithCCSanddirectaircapturefromtheliterature[37][38].Thecombinedcarbonremovalsfromthesesourcesareroughly1,000,1,400,and1,800MtCO2peryearin2050overthelow,medium,andadvancedcases,respectively.TheadvancedandlowertechnologyassumptionsfortheelectricityandtransportationsectorsrelylargelyupontheNationalRenewableEnergyLaboratory’sAnnualTechnologyBaseline.Theadvancedassumptionsforthebuildingsandindustrialsectorsdrawontheexistingliteratureandprogrammaticgoalsfortheadvancedcasesandslowerimprovementsinthelowercases,whicharemorealignedwithstandardmodelparameters.Fornon-CO2reductions,theadvancedtechnologyassumptionsacceleratetheavailabilityoflow-costtechnologiesbutdonotalterlong-termcosts.Oilandnaturalgaspricesarecalibratedtothe2021EIAAnnualEnergyOutlook’soilandgassupplycasesinthereferencescenario,i.e.,withoutanet-zero2050target.PopulationandGDP,thefinalsetofassumptions,spancompoundannualgrowthratesfrom2020to2050of0.5%to0.7%forpopulationand1.1%to1.8%forGDP.Also,theLULUCFmodelingeffortincludedtheuseof5differentmodelstogeneratebusinessasusualandpotentialmitigationoutcomesfromdifferentland-basedactivities,includingafforestation,improvedforestmanagement,harvestedwoodproductsstorage,andfirereductiontechniques.Thisexerciseincludedalignmentofseveralkeyinputsandparameters,includinguseofinputdatafromtheForestInventoryandAnalysisdatabaseand,insomecases,application22THELONG-TERMSTRATEGYOFTHEUNITEDSTATESofSharedSocioeconomicPathway(SSP)2informationformacroeconomicdrivers.ThelandusemodelsappliedinthisanalysisdidnotincorporateassumptionsofdemandofCCSorbioenergyasmitigationoptions,asthesemodelingaspectswereaccommodatedinGCAMandOP-NEMS.3.4ECONOMY-WIDEPATHWAYSTO2050NET-ZEROEMISSIONSAchievingthe2050net-zerogoalwillrequirereducingnetU.S.emissionsfromroughly6.6GtCO2ein2005(and5.7GtCO2ein2020),tozerobynolaterthan2050.Asdescribedabove,thisreductioncanresultfromcombinationsoffivemajorcategoriesofaction:energyefficiency;decarbonizingelectricity;fuelswitchingandenergytransitions;sequesteringcarbonthroughforests,soils,andCO2removaltechnologies;andreducingnon-CO2emissions.Figure3presentsavisionforhowsuchcategoriesofactioncancombinetoreachnet-zero.Thisfigureshowsarepresentativepathwayfrom2005netemissionslevelsthrough2050intheformofawaterfallchart(theleft-handsideofthefigure).Thisrepresentativepathwayprovidesaroughapproximationforreachingnet-zeroemissionsusingcontributionsfromallsectors.Table1:Long-TermStrategyScenarios.Toexploremultiplewaystoreachournet-zeroemissionsgoalin2050,thisanalysisincludestwelvescenarios(shownintheleftmostcolumnofthetable).The‘BalancedAdvanced’scenarioincludesmediumlevelsofcarbonremovalsfromtheatmospherethroughourlanduse,landusechange,andforestry(LULUCF)sinkandcarbondioxideremoval(CDR)technologies,andadvancedtechnologyassumptionsallowingforabalancedapproachacrosssectors.Thenextsixscenariosexplorelowertechnologyassumptionsforelectricity,transportation,industry,buildings,non-CO2,andcarbonremovals,respectively.Nextisascenariothatincludeshigherlevelsofcarbonremovalscombinedwithlowertechnologyassumptionsformultiplesectors.Thelastfourscenariosexplorehighandlowoilandgaspricesensitivities,andhighandlowpopulationandGDPgrowthprojections.TableforLTSLTSScenarioTechnologyAssumptionsbySectorModel(s)UsedCarbonRemovalElectricityTransportationIndustryBuildingsNon-CO2GCAMOP-NEMSBalancedAdvancedMediumAdvancedAdvancedAdvancedAdvancedAdvancedxLowerNon-CO2MediumAdvancedAdvancedAdvancedAdvancedLowerxLowerBuildingsMediumAdvancedAdvancedAdvancedLowerAdvancedxLowerIndustryMediumAdvancedAdvancedLowerAdvancedAdvancedxLowerTransportationMediumAdvancedLowerAdvancedAdvancedAdvancedxLowerElectricityMediumLowerAdvancedAdvancedAdvancedAdvancedxLowerRemovalsLowerAdvancedAdvancedAdvancedAdvancedAdvancedxxHigherRemovals/LowerTechnologyHigherAdvancedLowerLowerLowerLowerxxHighOil&GasPriceMediumAdvancedAdvancedAdvancedAdvancedAdvancedxLowOil&GasPriceMediumAdvancedAdvancedAdvancedAdvancedAdvancedxHighPopulation&GDPMediumAdvancedAdvancedAdvancedAdvancedAdvancedxLowPopulation&GDPMediumAdvancedAdvancedAdvancedAdvancedAdvancedx23THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTheright-handsideofthefigureshowssevenadditionalscenariosfromouranalysisthatarebasedondifferentassumptionsabouthowtechnologiesandpolicieswillevolveovertime.Thisincludesa“balancedadvanced”scenariowithhighlevelsofactionacrossallsectors,aswellasscenarioswhereoneofthesectors(buildings,industry,transportation,electricity,non-CO2,landsink)contributesalowerlevelofreductions.Thesealternatescenariosservetoillustratehowthebalanceacrosstechnologiesandpolicystrategiescouldvarywhilestillreachingthenet-zero2050goal.Severalbroadlessonsfromthisfigureareclear.First,intheabsenceofadditionalpolicies,emissionswouldremainlargelyflatmovingforward.Resultsinthefigureshowreductionsfromabaselinescenarioto2050—thatmeansthatonlyreductionsbeyondthebaselinescenarioarereflectedinthecoloredbars.Achievingnet-zeroemissionswillrequireactionsthatgofarbeyondbusinessasusual.Second,roughly4.5Gtofthe6.5Gtannualreductionfrom2005levelswilllikelycomefromtransformingtheenergysystem.ThisstartswithdecarbonizingFigure3:EmissionsReductionsPathwaystoAchieve2050Net-ZerointheUnitedStates.Achievingnet-zeroacrosstheentireU.S.economyrequirescontributionsfromallsectors,including:efficiency,cleanpower,andelectrification;reducingmethaneandothernon-CO2gases;andenhancingnaturalandtechnologicalCO2removal.Theleftsideofthefigureshowsarepresentativepathwaywithhighlevelsofactionacrossallsectorstoachievenet-zeroby2050.Therightsideshowsasetofalternativepathwaysdependingonvariationsinuncertainfactorssuchastrendsinrelativetechnologycostsandthestrengthofthelandsectorcarbonsink.ALTERNATEPATHWAYSTO2050NET-ZEROREPRESENTATIVEPATHWAYTO2050NET-ZERO24THELONG-TERMSTRATEGYOFTHEUNITEDSTATESelectricitybyshiftingtorenewablesandotheremissions-freepower.Thisshiftcouldleadtoover1Gtofannualreductionby2050.Asecondpillarofenergytransformationissimplytouseenergymoreefficientlytoprovidethesameservices.Solutionslikebetterinsulation,advancedheatpumpsforspaceandwaterheating,andefficientcomputersandelectronicscansaveconsumersbillionsontheirannualenergybills.Cuttingenergywastealsoreducestherateofinvestmentneededfornewcleanenergygenerationasdemandgrows.Thispillaralonecouldcontributeroughly1Gtofannualreductionsby2050.Athirdpillarofenergytransformationistoswitchasmanyusesaspossibletocleanenergy—includingcleanelectricity,butalsoincludinglow-carbonfuelsandcleanhydrogen.Efficientelectrificationoftransportation,buildings,andotherendusescanalsotransformtheenergysectorbyreducingoverallenergydemand.Electricmotorsinvehicles,forexample,areapproximatelythreetimesmoreefficientthaninternalcombustionengines,andelectricheatpumpsareuptothreetimesmoreefficientthanheatingwithnaturalgasorelectricresistance.Theseactivitieswouldleadtonearly2Gtofannualreductionsby2050.Third,othernon-CO2GHGemissionsrepresentacriticalcomponentoftheoverallreductionstrategy,collectivelyrepresentingroughly0.5Gtofreductionsby2050.Thesegaseshavesourcesacrossmanysectorsandincludemethaneemissionsfromagriculture,wastemanagement,andfossilfueluse,HFCsusedinrefrigeration,andN2Ofromagricultureandindustry.Suchgasesoftenofferlowcostandhighimpactreductions.Forexample,globally,methaneaccountsforhalfofthenet1.0°Cofwarmingalreadyoccurring.Becauseofitsrelativelyshortlifetimeintheatmosphere,comparedtoCO2,rapidlyreducingmethaneemissionsisthesinglemosteffectivestrategytoreducewarmingoverthenext30yearsandiscrucialinkeepingtothe1.5°Climit.TheUnitedStatesco-leadswiththeEUtheGlobalMethanePledgethataimstoeliminateover0.2°Cofpotentialwarmingby2050bycuttingglobalmethanepollutionatleast30%by2030relativeto2020levels.AsofOctober2021,over30countriesrepresentingabout30%ofglobalemissionsand60%oftheglobaleconomyhadjoinedthePledge(SeeBoxinChapter5).AsdetailedintheNCS,theUnitedStatesisimplementingcomprehensiveactionstodrivedownmethaneinthisdecade,includingnewstandardsforlandfillsandoilandgasoperationsaswellasmajorinvestmentstoremediateabandonedcoal,oil,andgasminesandwells.TheUnitedStatesisalsocommittedtoincentivesandinnovationstoreduceagriculturalmethaneandagriculturalN2Oemissions.Finally,aglobalHFCphasedownisexpectedtoavoidupto0.5°Cofglobalwarmingby2100.Fourth,removingCO2fromtheatmosphereisanecessarycomponentforreachingnet-zero.Althoughmostemissionsacrosstheeconomycanbeeliminatedthroughtheabovestrategies,afewprocessesoractivitiesthatleadtoemissionsarecurrentlydifficultorcostlytoeliminateorhavenoviableexistingsubstitutes,anddespitemanyavailablecost-effectivemitigationopportunities,non-CO2GHGemissionscannotbefullyreducedtozero.Thismeansthatreachingnet-zerowillrequireadditionalcontributionsfromremovalsuntilviablezero-emissionsolutionsaredevelopedanddeployed.Overall,theseremovalswouldcomefromtwobroadcategoriesofactivities.Oneisthroughnature-basedapproachesthatrelyonnaturalcarbonsinks—landandocean—byexpandingorenhancingconservation,restoration,sustainablemanagementandotheractivitiesthatwouldenhancenaturalremovalofcarbonaswellasprotectourvitalnaturalecosystemsandrelatedservicesandbiodiversity.AsecondsetofapproachesisthroughvarioustechnologiesandprocessesthatdirectlycaptureCO2fromtheatmosphereandstoreit(suchasdirectairoroceancapture,bioenergywithCCS,orenhancedmineralization).Technologiescapableofcarbondioxideremovalareavailabletoday,butatnascentstagesandthereforewillrequireadditionalresearch,development,anddeploymentnowthrough2050(morediscussionofCDRtechnologiescanbefoundinsection6.4).25THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTheenergysectorispivotalforachievingnet-zeroemissionsby2050.Achievingnet-zeroispossiblethrougharangeofpathways,whichdependonhowtechnologiesandpoliciesevolveoverthethree-decadeperiod.Nevertheless,bymodellingarangeofpathwayswithplausibleassumptionsforthisevolution(seeFigure4),wecandistinguishbroadtrendsandimportantdriversoftheenergysectortransformation.CHAPTER4:TRANSFORMINGTHEENERGYSYSTEMTHROUGH2050Figure4:U.S.EnergyCO2Emissionsto2050byEconomicSector.ElectricityCO2emissionsanddirectCO2emissionsfromthetransportation,buildings,andindustryfalldramaticallyinallscenarios,withthegreatestreductionscomingfromelectricity,followedbytransportation,andnon-landsinkcarbondioxideremovals(CDR)increase.Notes:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingbothGCAMandOP-NEMS,projectionsareshowninten-yeartimesteps.0.01.02.0200520202050EnergyEmissions(GigatonsCO2)TransportationBuildingsIndustryElectricityCDR26THELONG-TERMSTRATEGYOFTHEUNITEDSTATES4.1ELECTRICITYTheUnitedStateshassetagoalfor100%carbonpollution-freeelectricityby2035,andthisgoalwillprovideanimportantfoundationfortheLong-TermStrategyoftheUnitedStates.Electricityisusedineveryeconomicsector,andall2050net-zeropathwaysdependonrapidlydecarbonizingelectricityandexpandingtheuseofthisdecarbonizedelectricityintoasmanyusesaspossibletodisplacepollutingfuels.Theelectricitysector,whichcontributesaboutaquarterofallU.S.GHGemissions,hasbeenreducingCO2emissionsforyears,withmajorshiftscausedinpartbyincreasesinrenewablesanddecreasesincoal-firedgeneration(seeFigure5).Continuedcostreductionsingenerationandstorageareexpectedtoenableevenmorerapidreductionsofemissionsfromthissector.Newpolicies,incentives,marketreforms,andotheractionswillbeneededtoensurethatelectricitysectoremissionscontinuetodecreaseastotalelectricitydemandincreases.Theelectricitysectorwillcontinuetoevolverapidlyasitdecarbonizes.ExpectedcontinuedcostreductionsinrenewablegenerationaswellasbatteryandotherstoragetechnologiescouldseeemissionsdecreasesofFigure5:U.S.ElectricityGeneration2005-2050.Generationbysourceintrillionkilowatt-hours.Totalgenerationexpandsto2050duetoincreaseduseofcleanelectricityinnewapplicationsintransportation,industry,andbuildings.Renewablegenerationincreasesrapidlytokeeppacewithgrowingelectricitydemandandensurethattheshareofrenewablescontinuestoexpandto2050.Note:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingbothGCAMandOP-NEMS,projectionsareshowninten-yeartimesteps.0.02.04.06.0200520202050ElectricityGeneration(TrillionkWh)Fossilw/CCSFossilw/oCCSNuclearRenewablesNon-FossilCombustionBiomassw/CCS27THELONG-TERMSTRATEGYOFTHEUNITEDSTATESroughly70-90%by2030onapathtowardthe2035100%cleanelectricitygoal.AsshowninFigure5,solarandwindgenerationcontinuestoincreasesubstantiallythrough2050,whileexistingnucleargenerationremainsinoperationandcouldseegrowthinthe2030sand2040s.Unabatedfossilgeneration(coalorgasgenerationwithoutCCStechnology)declines,andexistingfossilfueledplantsstarttobefittedwithcarboncapture.By2050,cleangenerationprovideszeroemissionelectricitytotherestoftheeconomy,withallelectricityproviding15-42%ofprimaryenergy.Recentanalysessuggestthatwholesaleelectricityprices,onaverage,areunlikelytochangesignificantlyasweshifttoacleanergridby2030,withpriceimpactestimatesrangingfroma4%decreasetoa3%increase[39].Additionally,thetransitiontocleanelectricityisexpectedtoreduceexposureofU.S.consumerstofuelsupplyshocks[40].Investmentincleanenergygenerationmustcontinuethroughmid-centuryasoverallelectricitygenerationincreasestomeetdemandgrowthfromothersectors.Averageannualtotalcapacityadditionswithoutstoragefrom2021to2030rangefrom58gigawattsperyear(GW/yr.)to115GW/yr.;in2031to2040theyrangefrom54GW/yr.to167GW/yr.;andin2041to2050theyrangefrom67GW/yr.to123GW/yr.Storagecapacityadditionsfrom2021to2030average0.4GW/yr.to2.7GW/yr.;in2031to2040,theyrangefrom3GW/yr.to40GW/yr.;andin2041to2050theyrangefrom11GW/yr.to64GW/yr.Thisrapidevolutionandscaleofchangeintheelectricitysectorisambitious,withhighandsustaineddeploymentofnewtechnologiesthroughmid-century.Manysignificantchallengesandbarriersexist[14][22].Theelectricitytransitionwillrequireaddingsignificantamountsofnewzero-carbonelectricitycapacityatasufficientpacetoreplaceuncontrolledfossilfuel-firedgenerationwhilealsoprovidingamplecleansupplyforagrowingeconomywithincreasedelectrification.Newtransmission,distribution,andstorageinfrastructurewillbeneededtomaintainandimprovegridreliability,includingadaptingtheelectricgridtobeflexibletochangingsupplyanddemandoverallincrementsoftime.Inparticular,longer-durationstoragesolutionsandappropriateincentivemechanismswillbecritical.Absentnewaction,supplychainsmaybecomestressedbylimitedavailabilityofrawmaterials(suchasrareearthelements),manufacturingcapacity,andskilledworkforce.Somepathwaysmayalsorequiresignificantexpansionofcarboncaptureandstoragetechnologiesduringtheoveralltransition,whichbringspecificchallengesaroundtechnologydevelopmentandsiting.Thesechallengesaresubstantialbutcanbeaddressedthroughanintegratedstrategyofinvestment,innovation,andnewtechnologydeployment.Large-scaledeploymentofrenewablescanbeacceleratedbyinvestmentsingridinfrastructureandadvancedtechnologies.Gridinfrastructureinvestments,includingthebuildoutofnewlong-distance,high-voltagetransmissionprojects,canenhanceresilience,improvereliability,betterintegratevariablegenerationresources,lowerelectricitycosts,andunlockthebestcleanenergyresourcesbyconnectingthemtodemandcenters.Significantdeploymentofenergyefficiencycanalsohelpreducethescaleofinvestmentrequiredbyloweringthetotalenergydemandthatmustbemet.Analysesshowthatasthesectorbecomesincreasinglydecarbonized,advancedtechnologieswillbebroughtonlinetomeetpeakloadandadjusttoseasonalchangesindemand.Advancedtechnologies—whichcouldincludecleanhydrogencombustionorfuelcells,enhancedgeothermalsystems,long-durationenergystorage,advancednuclear,andfossilgenerationwithCCS—canprovidecleanfirmresourcesthatcanbalanceincreasedvariablegeneration.However,thesetechnologiesrequirearapid,sustainedaccelerationinresearch,development,anddeployment.Thesignificantinvestmentsingenerationandtransmissionwillunderpinjobgrowthacrossthenation,creatingopportunitiesincitiesandruralareasalike,particularlywhenpairedwithworkforcetraining.Expansionofthetransmissionsystem,strongerinterregionalcoordination,anddistributedgenerationalsoprovideresiliencetonaturaldisasters,savinglivesandprotectingbusinesses.28THELONG-TERMSTRATEGYOFTHEUNITEDSTATESRAPIDDECARBONIZATIONINTHEU.S.ELECTRICITYSECTORISUNDERWAYTheelectricitysectorintheUnitedStateshasbeendecarbonizingrapidly,withsignificantincreasesinrenewabledeploymentinrecentyears.Theshifttolower-emissionssourceshasbeenunderwayfordecades,withearlycontributionsfromnuclearandthenfossilgas.Morerecently,sincearound2010,federalinvestmentpolicies,taxcredits,andregulatoryactions,aswellasstatepolicies,researchanddevelopment,andmarkettrends,drovesignificantrenewabledeployment.Atthesametime,between2010and2019,morethan546coal-firedpowerunitsretired,totaling102GWofcapacity,withanother17GWofcapacityplannedforretirementby2025[41].ThishasledtoadramaticshiftinthesourcesofU.S.electricity,withrenewablesnowaccountingformoregenerationthancoal(Figure6).Inaddition,thesumofcoalandnaturalgasgenerationhasalsodeclinedinthelastdecade,pointingtotheimportantroleofrenewableenergy.Oneofthechallengestoreachthe2050net-zerogoal(aswellasthe2035100%cleanelectricitygoal)isthelargeamountofnewzero-emissioncapacity(primarilyrenewables)thatwillneedtobedeployedannuallytoenableanincreasinglylargeshareofcleanelectricitygeneration.Figure7showssomeindicativeestimatesofthemagnitudeoftheannualcapacityadditionsneededtoremainonpacetowardourgoals,incomparisontorecenthistoricallevelsofcapacityadditions.Recenttrendsinrenewabledeploymentareencouraging.Solarandwindcapacityadditionswereabout32GWin2020,thehighestonrecord,andareexpectedtobeabout28GWin2021.Accelerationwillbeneededbutthedeploymentratehasbeengrowingquickly.28THELONG-TERMSTRATEGYOFTHEUNITEDSTATES29THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES29Figure6:AnnualU.S.ElectricityGenerationfromAllSectors1950-2020(trillionkilowatt-hours).Theelectricitysectorhasbeenrapidlydecarbonizingsince2008.Thisfigureshowselectricitynetgenerationinallsectors(electricpower,industrial,commercial,andresidential)andincludesbothutility-scaleandsmall-scalesolar.Rapidincreasesinsolar,wind,andotherrenewablegenerationmeansthatin2020,forthefirsttime,renewablegenerationsurpassedcoalgeneration.Coalgenerationhasdeclinedrapidly,replacedbynaturalgasandrenewables.Source:EIA[42].Figure7:ElectricGenerationCapacityAdditions2000-2050.Renewablecapacityadditionshavebeengrowingrapidlyinthepastdecade(left)andaremorecloselyapproachinglevelsthatwillbeneededtosustaintheoveralldecarbonizationtrendinelectricityneededtoreachthe2050goal.Arepresentativepathway(center)showsdeploymentoftotalzero-carbontechnologiesroughlyontheorderof60–70GWperyear.Diversescenariosinthisanalysisshowarangeofpotentialpathwaystoachievenetzero(right).Note:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingGCAM.Otherscenariosnotshowninthefigurehavecumulativenuclearcapacityadditionsrangingupto90–100GWthrough2050.Source(percentageof2020total)NaturalGas(40%)Renewables(21%)Nuclear(20%)Coal(19%)Other(<1%)0.00.51.01.52.019501960197019801990200020102020ElectricityGeneration(TrillionkWh)010203040506070802021-2050Average2021-20302031-20402041-205001020304050607080200020102020010203040506070800.05OtherNuclearSolarWindFossilw/CCSFossilw/oCCSNewInstalledCapacity(Gigawattsperyear)NewInstalledCapacity(Gigawattsperyear)HISTORICALCAPACITYADDITIONSREPRESENTATIVEPATHWAYTO2050NET-ZEROALTERNATEPATHWAYSTO2050NET-ZERO30THELONG-TERMSTRATEGYOFTHEUNITEDSTATESTheUnitedStateswillcontinuetoincreasetheuseofelectricityandsustainablyproducedlow-carbonfuelsinthetransportationsectorwhileshiftingawayfromfossilsources(Figure8).Overtime,electricity,carbonbeneficialbiofuels,andhydrogenwillbecomeincreasinglyclean.Theavailabilityandadoptionoftheselow-carbonfuelsinthecomingdecadeswilllargelydependontheeconomicsofproductionand/orprocurement,thecompetitivenessofbioenergyandhydrogencomparedtoalternativelow-carbontechnologiesacrosssectors,policysupport,private4.2TRANSPORTATIONThetransportationsectorprovidesvitalmobilityservicesforpeopleandgoodswithon-roadvehicles,planes,trains,ships,publictransportation,andawidevarietyofothermodes.Itiscurrentlythehighestemittingsector,representing29%ofallU.S.emissions[27].Toreduceemissionstonet-zeroby2050wewillneedtoensurethatzero-emissionvehiclesdominatenewsalesformosttypesofvehiclesbytheearly2030s,aswellasinfrastructuretosupportalternatemodesoftransportation,suchastrains,bikes,andpublictransit.Figure8:U.S.TransportationFinalEnergyUse2005-2050.Overalltransportationenergyinexajoules(EJ)decreaseswhiletheuseofelectricityandalternativefuels,includingbiomass-derivedfuelsandhydrogen,increasestopowernearlythefullU.S.transportsystemby2050.Whilelight-dutyvehiclesarealmostallelectricby2050inmostscenarios,thereisuncertaintyinothertransportationsectors.Uncertaintiesinthefutureshareoflow-carbonbioenergyvs.hydrogenmakescanaffectthepotentialforelectrificationinthesector.Theseresultsshowenduseconsumptioninsteadofservicedemand(e.g.,permiletravelled),soelectricitydemandappearssmallerthanalternativefuelsdemandduetothemajorinherentefficiencyadvantagesofelectricvehicles.Note:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingbothGCAMandOP-NEMS,projectionsareshowninten-yeartimesteps.0102030200520202050TransportationEnergy(Exajoules)AlternativeFuelsElectricityFossil31THELONG-TERMSTRATEGYOFTHEUNITEDSTATESAnintegratedstrategytoaddressthesesubstantialchallengescanhelpacceleratethedevelopmentandrapidexpansionofnewtransportationtechnologies.Anexpandednetworkofpublictransitoptionsandinfrastructurewillincreaseurbanmobility,helpingtoreduceemissionsandincreaseequityinmobility.Electrifyingsegmentsoftherailsystemwilldecarbonizetheexistingrailsystemwiththeaddedbenefitofenablingamorerobustelectricgridalongrailroad“rightofway.”Additionally,“vehicletogrid”innovationsmayprovidesupportforgridservices.Acceleratedresearch,development,demonstration,anddeploymentoflower-carbonfuels,suchascleanhydrogenandsustainablebiofuels,willcontributetothedecarbonizationofapplicationsthatmaybemoredifficulttoelectrifyincludingaviationandmarinetransportationandsomemedium-andheavy-dutytruckingsegments.4.3BUILDINGSBuildingshouseourpopulationandprovideaworkingenvironmentforcommercialsectorsincludingoffices,collegesandK-12schools,restaurants,grocerystores,andretailshops.Homesandcommercialbuildingsareresponsibleforoverone-thirdofCO2emissionsfromtheU.S.energysystem.Ofthis,roughlytwo-thirdsofbuildingssectoremissionscurrentlycomefromelectricity,withtheremaindercomingfromdirectcombustionofgas,oil,andotherfuelsforspaceheating,waterheating,cooking,andotherservices,andbuildingscurrentlyaccountforaboutthreequartersofU.S.electricitysales[43].Electricityisusedinbuildingsforlighting,spaceheatingandcooling,waterheating,electronicsandappliances,andotherservices.CO2emissionsfrombuildingshavebeenfallingsince2005,duetoincreasesinenergyefficiency,thedecarbonizationoftheelectricitysector,andamodesttrendtowardstheelectrificationofenduses.Theseemissionsreductionshavebeenachievedevenascommercialbuildingsquarefootagehasincreasedbymorethan25%andthepopulationhasgrownbymorethan10%since2005.Allbuildingsneedtobedecarbonizedwithanemphasisonstrategiesthatdeliverforoverburdenedandunderservedcommunities.Forexample,intheresidentialsector,householdswithanannualincomebelowinvestmentand,inthecaseofbio-basedenergy,theabilitytominimizepotentialnegativelandcarbonoutcomesandotherenvironmentalimpactsofbiomassproduction.Althoughdemandfortransportationservicesincreasesthroughmid-century,thetotalenergyconsumedinthissectordeclinesduetoacombinationofregulationsandtechnologicaladvanceswhichdriveefficiencyimprovementsanddeliversocietalandconsumerbenefits.AcentralcomponentoftheU.S.Long-TermStrategyintransportationistheexpandeduseofnewtransportationtechnologies—includingarapidexpansionofzero-emissionvehicles—inasmanyapplicationsaspossibleacrosslight-,medium-,andheavy-dutyapplications.Already,thegrowingpopularityofelectricvehicles(EVs),supportedbyincentivesandcontinuedadvancesinbatterytechnology,isspurringgreaterEVadoptionandindustrygoalsforevenhigherEVsales.OthertechnologiescanserveasimportantcomplementstoEVs.ThePresident’sgoalandassociatedpoliciestoensurehalfofallnewvehiclessoldin2030zero-emissionsvehicles(includingbatteryelectric,plug-inhybridelectric,orfuelcellelectricvehicles)willcontinuetospurgrowthacrossallzero-emissionvehicletypes.Thisrapiddeploymentofzero-emissionsvehiclesisambitiousandwillneedtooccuratalargescaleacrossallvehicletypes.Manychallengesandbarriersexist[14][22][25].Forexample,costsforelectrictechnologies,fueling,andcharginginfrastructureremainhighinsomeapplications.Sometransportationsegments,suchasaviation,willlikelyremaindifficulttoelectrifyandsomelegacyvehicleswillcontinuetobenecessaryinthenearterm,bothofwhichwouldrequirealternatesourcesoflow-carbonfuelsthathaveyettobedeployedatthenecessaryscale.Theexistingbuiltenvironmentcreatesalsohighdependencyonowner-occupiedvehiclesandpresentsnumerousobstaclestoalternatemobilityoptionsandshiftingbetweenmodessuchastransit,biking,orwalking.32THELONG-TERMSTRATEGYOFTHEUNITEDSTATESelectrification.Heatpumpsandotherelectricheatersandelectriccookingaccountformorethan60%ofsalesby2030andnearly100%ofsalesby2050.Energydemandinbuildingsisreducedby9%in2030and30%in2050.Whilerecenttrendsareencouraging,thebuildingsectorpresentssomeuniquechallengestorapiddecarbonization.Foremostistheoften-longlifetimeofbuildings.Manybuildingsbuilttodaywillstillbeinactiveuseby2050,whichmeansthatevenimmediateactionstoimprovenewbuildingstakeyearsbeforemakingasignificantimpactintheoverallbuildingstock.Thesefactorsaffectallaspectsofbuildingsincludingtheoutershell;heating,ventilation,andairconditioningsystems;andappliancesandlighting—althoughsomeofthesearemoreamenabletoretrofittingthanothers.Inaddition,energyefficiencyandefficientelectrificationhavebarriersrelatingtotheirupfrontcoststructure,financing,competinglandlordandtenantincentives.Theseissuescanbeparticularlydifficultinunderserved$60,000accountfornearly50%ofallhouseholdenergyconsumption,makingitessentialthateffortstodecarbonizebuildingsareaccessibletoallhouseholds[44].Thekeydriverofreducingbuildingemissionsisefficientuseofelectricityforenduses(suchasheating,hotwater,cooking,andothers).Alongsidethedecarbonizationofelectricity,thesechangescanbringbuildingsectoremissionstonear-zeroby2050.Acrossmultiplepossiblepathways,buildingefficiencyimprovementsalsoreducetheoveralldemandforenergybythesector,despitethesubstantialgrowthinthenumberofbuildings,floorspace,andpopulationexpectedthrough2050(Figure9).Withinthisoveralldecreaseinenergydemand,theshareofelectricityinfinalenergydemandgrowsasendusesareelectrified,fromabout50%in2020to90%ormoreby2050becausetheon-sitecombustionofgas,oil,andotherfuelsdecreasessubstantially;however,thegrowthisalsolimitedthroughenergyefficiencyandefficientFigure9:U.S.BuildingsSiteEnergy2005-2050.Overallbuildingsiteenergyuseinexajoules(EJ)decreasesatthesametimeascertainapplications(e.g.,heating)switchfromfossilfuels(andsomebiomass)tocleanelectricity.Note:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingbothGCAMandOP-NEMS.ElectricityFossil051015200520202050BuildingsEnergy(Exajoules)33THELONG-TERMSTRATEGYOFTHEUNITEDSTATESconditions,improvinghealthandsafety.Theroleofstateutilityregulatorswillbeespeciallyimportant,asapprovalofnewratestructuresandconsumerincentiveprogramswillbevitalinrealizingthefullpotentialofconsumerbenefits.Finally,buildingimprovementswillcomefrommanufacturing,construction,andinstallationperformedbyskilled,well-paidAmericanworkersincommunitiesacrossthecountry.4.4.INDUSTRYTheU.S.industrialsector,currentlyproducesroughly23%ofU.S.GHGemissionsand30%ofemissionsfromtheenergysystem[45].Itisheterogeneous,producingawiderangeofproductswithdiverseandsometimesspecializedprocesses.Theenergy-intensiveandemissions-intensiveindustriesincludemining,steelmanufacturing,cementproduction,andchemicalproduction,andcollectivelyproducenearlyhalfofoverallindustrialemissions.InadditiontotheCO2emissionsresultingfromindustrialdemandforelectricity,theindustrialsectoremitsGHGsdirectlyfrommanyoperationsandprocessesincludingtheuseoffossilfuelsforonsiteenergyuseandasfeedstocks,directprocessemissionsofCO2fromcementproductionandotherindustries,andemissionofnon-CO2GHGssuchasN2Ofromnitricandadipicacidproduction.Althoughtherearemanyhard-to-decarbonizeelementsofindustrialactivities,investmentsintechnologiesforadvancednon-carbonfuels,energyefficiency,andelectrificationcanreduceoverallindustrialsectorCO2emissionsby69-95%by2050.AlargerangeofpotentialpathwaysfortheindustrialsectorareshowninFigure10.Overallenergyusedropsinmostscenariosthroughenergyefficiencyandmaterialsefficiencyinvestments.Inthesescenarios,overallelectricityuseinthesectorgrowsonlyslightlyduetoelectrification.However,inscenariosthatrelyonalargequantityofhydrogen,electricityuseincreasesdramaticallytoproducethehydrogenthroughelectrolysis.Inallscenarios,low-carbonfuels(includingelectricity)growasapercentageoftotalenergyuse.communities,whichwillalsoneedwidespreadaccesstoretrofitsandnewbuildingtechnologies,thoughinnovativefinancingtoolssuchasinclusiveinvestmentprogramscandeliversubstantialbenefitstothesecommunitieswhilereducingoreliminatingfinancingbarriersandensuringconsumerprotections.Toaddressthesechallenges,pursuingmultipleoptionseffectivelyhelpachievethenecessaryrapidemissionsreductionsinbuildingswhilealsoreducingtheenergycostburdenforfamiliesandbusinessesandimprovingthehealthandresilienceofcommunities.Therearethreeimportantsourcesofemissionsreductions:technologicaladvancesincludingfromenvelopeimprovements(e.g.,atticandwallinsulation,sealingleaks,andefficientwindows),improvedefficiencyofelectricenduses(e.g.,lighting,refrigeration,appliances,andelectronics),andtheefficientelectrificationofspaceandwaterheating,cooking,andclothesdryinginbothexistingandnewbuildings.Therapiddeploymentofheatpumpsforspaceheatingandcoolingandwaterheatingisthecentralstrategyfortheefficient,flexibleelectrificationofbuildings.Byincreasingtheamountofdemand-responsiveheating,cooling,andwaterheatingonthegrid,thesetechnologiescanrespondtoshiftsinrenewablegenerationlevelsonshortnoticeandreducetheoverallcostofalow-orzero-carbongenerationmix.Efficientandelectrifiedbuildingsprovidesubstantialconsumerbenefits.Themostimportantbenefitisreducedutilitybillsforhouseholdsandbusinesseswhicharebothdirect(throughlowerenergyusage)andindirect(throughlowerenergyprices).Moreefficientbuildingssignificantlyreduceselectricitydemandandlessenwinterpeakingloadsasthesectorelectrifies,reducingthecostofnewgeneration,transmission,anddistribution,whichinturnreducesenergypricesforAmericanfamiliesandbusinesses.Thesebillsavingswouldbemostbeneficialtolow-incomehouseholds,whichtypicallyfacethegreatestenergyburden.Buildingscanalsosupportelectricvehiclecharginginfrastructureandrooftopsolarinstallations,keyelementsofthebroaderenergytransition.Moreefficientbuildingsalsoretainindoortemperatureforlongerduringpoweroutagesunderextremeweather34THELONG-TERMSTRATEGYOFTHEUNITEDSTATESthespecificneedsofeachsubsector.Keystrategiesincludeenergyefficiency,materialefficiency,electrification,adoptionoflow-carbonfuelsandfeedstocks,andCCS.Energyefficiency,wasteheatrecovery,andacceleratedadoptionofadvancedtechnologiessuchasadditivemanufacturing,cansignificantlyreduceenergydemandandlowercoststobusinesses.Materialefficiencyincorporatesstructuralchangesinmanufacturingthatincludeproductrecyclingandreuse,materialsubstitution,anddemandreduction.Electrificationofheated,fuel-consumingindustrialprocessesandequipmentisaviablepathwayforsomesubsectors,suchaslightindustry.Low-carbonfuelsandfeedstocks,includingcleanhydrogenandlow-carbonbiofuels,canreduceemissionsfromprocessesthataredifficulttoelectrify.Finally,CCScanbeusedforemissionsthatarehardtoabatethroughothermeans,particularlyinthecement,chemicals,andironandsteelindustries.Increasedinvestmentsinresearch,development,demonstration,anddeploymentwilladvancetechnologiesinproductionofironandsteel,cement,chemicals,andotherindustries,enablingthesesectorstoadoptlow-carbonproduction.Reducingenergy-relatedGHGemissionsfromindustrypresentsasetofuniquechallenges[14][22][26].Aprimaryfeatureofthissectoristhatitisdiverse:unlikeelectricityorbuildings,forexample,whoseemissionscomefromarelativelysmallsetofactivities,industrialactivitiesandinfrastructurearedesignedaroundalargesetofprocesses.Someoftheseprocessesmighthaverelativelystraightforwardsubstitutes,butinothercaseseitherthosesubstitutesmaynotexistyetormightbehighercost.Insomecases,alternatesourcesofprocessheatingmayneedtobeidentified.Inothercases,CCSapplicationsmaybeneededbutthesemaybeexpensiveorinfeasibleatexistingproductionfacilities.Atthesametime,scalingupofmaterialefficiencycouldbechallengingbecauseofproductdesignlimitationsorconsumerdemand.Manyofthesechallengesalsoaffectthenon-CO2emissionsfromindustry,whicharediscussedfurtherinChapter5.Inresponsetothesechallenges,theindustrialenergytransitioncanbeenabledtodecarbonizeatasufficientlyrapidpacethroughadiversesetofapproachestailoredtoFigure10:IndustryFinalEnergyUse2005-2050.Overallindustrialenergyuseinexajoules(EJ)decreasesto2050whilecertainapplicationsswitchfromfossilfuelstocleanelectricity,hydrogen,orbiofuels.Electricityuseincreasesfurtherinscenarioswithlargerhydrogenproductionduetothehighelectricitydemandforthatpro-cess.Inthisanalysis,CCSindeployedinindustryforprocessemissions,butthereislimitedrepresentationofCCSonindustrialenergyinthemodelsweuse.Accordingly,itislikelythatagreatershareofindustrialfossilenergyemissionscouldbecapturedby2050thanisshownhere.Note:HistoricaldataarefromEIAMonthlyEnergyReviews,projectionsincludedatafromallLTSscenariosusingbothGCAMandOP-NEMS,projectionsareshowninten-yeartimesteps.05101520200520202050IndustryEnergy(Exajoules)Fossilw/oCCSFossilw/CCSElectricityBiomassw/oCCSBiomassw/CCSHydrogen35THELONG-TERMSTRATEGYOFTHEUNITEDSTATES5.1INTRODUCTIONNon-CO2GHGsmakeup20%oftheU.S.contributionstoglobalwarming[27].Non-CO2GHGsarehighlypotentheattrappinggases,manyofwhichhavegreaternear-termclimateimpactsthanCO2[36].AsshowninFigure11,threegasesmakeupthemajorityofnon-CO2GHGemissionsintheUnitedStates:methane(CH4),nitrousoxides(N2O),andfluorinatedgases(includingHFCs)[27].Thethreesourcesthatproducethelargestproportionofemissionsaresoilmanagement(i.e.agricultureandlanduse),livestock,andenergy.Whilemitigationopportunitiesexistformanysourcesofnon-CO2GHGemissions,costsandapplicabilityvary.Becauseitischallengingtoeliminateallofthesesources,someremainingnon-CO2emissionswillneedtobeoffsetin2050bynet-negativeCO2emissions.Thisanalysisestimatesthatthetotaltechnicalpotentialfornon-CO2GHGmitigationacrossallsectorsisapproximately35%withoutreducingtheunderlyingactivities[36].Reducingtheuseoffossilfuelsthroughefficiencyandfuelswitchingalsohasthepotentialtofurtherdrivedownnon-CO2GHGemissionsby19%giventherelationshipbetweenfugitivemethaneCHAPTER5:REDUCINGNON-CO2EMISSIONSTHROUGH2050Figure11:SourcesofU.S.Non-CO2GHGEmissions,2019.Contributionto2019U.S.GHGemissionsfromnon-CO2sourcespartitionedbytypeandsector.ThecontributionsareshowninCO2equivalent,meaningthattheyarerepresentedinproportiontotheirglobalwarmingcontribution100yearsafteremission.Approximatelyhalfoftheglobalwarmingcontributionofnon-CO2gasesin2019camefrommethane,withnitrousoxidecontributingthesecondmost,followedbyfluorinatedgases.36THELONG-TERMSTRATEGYOFTHEUNITEDSTATESdevelopmentofnewormoreeffectivemitigationtechnologiesandapproaches.Inaddition,inawaythatissimilartotheindustrialenergyemissionsdescribedinChapter4,thesourcesofnon-CO2emissionsarediverse.Thismeansthatindividualstrategiesmustbedevelopedforeachsub-sectorandgas.Inlightofthesechallenges,thisLTSanalysisofnon-CO2GHGmitigationpotentialassumesonlymodesttechnologicalandcostimprovementsovertime.Becausetheseassumptionsmaybeconservative,additional,lower-cost,andmorerapidreductionscouldberealized,andthiswillremainanareaofactiveinquiry.Achievingmoresignificantlong-termreductionsofnon-CO2GHGemissionswillrequiremajortechnologicaladvancesandnew,ormoreeffective,backstopmitigationoptions.Insectorswithlessdevelopedcurrentapproaches,thiscouldincludenewresearchanddevelopmentintoidentifyingandcommercializingnewtechnologiestoreducenon-CO2emissions.Inothersectors,newemissionsfromtheextraction,processing,andend-useoffossilfuels.ThesereflectmultipletechnologicaloptionsthatUnitedStatescanusetoachievethenecessaryreductionsinnon-CO2GHGemissionstoreachnet-zerototalemissionsby2050(Figure12).Underthesescenarioassumptions,thereremainnon-CO2GHGemissionsinthe2030and2050timeframes,whichmustbeoffsetbycarbondioxideremoval.Reductionsinnon-CO2emissionsfaceseveralchallenges.Firstisanunderdevelopedsetofmitigationstrategiesincertainsubsectors.Inpartbecauseofalackofhistoricalfocusonnon-CO2reductions,thesetofavailablemitigationapproachesforthesegasesisstillrelativelysmalland,inmanycases,inearlierstagesoftechnologicaldevelopment.Thismeansthatthrough2050,overallnon-CO2emissionscanbeheldroughlyconstantbydeployingcurrentlyavailablemitigationtechnologies.Achievinglong-termreductionsofnon-CO2emissionsbelowcurrentlevelsrequiresFigure12:PathwaysforNon-CO2Reductionsfrom2020to2050.Thisfigureshowstherangeofpathwaysavailablefornon-CO2mitigationfromtodayto2050acrossallmodeledscenarios.Inallscenariosthereissignificantreductionfromthe2020reference,highlightingtheimportanceofnon-CO2abatement.MethaneNitrousOxideFluorinatedgases0200400600200520202050Non-CO2emissions(MillionmetrictonsCO2equivalent)37THELONG-TERMSTRATEGYOFTHEUNITEDSTATESgas,suchassomeofthemethaneandN2Ofromtheagriculturesector,cannotbeabatedinthe2050timeframeevenafterapplyingallavailablemitigationtechnologies,andwillhavetobeoffsetbynegativeCO2emissions.5.2.1METHANEMethaneisapotentGHGandaccountsforabouthalfofthecurrentobservedwarming5of1.0°C,accordingtothelatestreportoftheIntergovernmentalPanelonClimate5Greenhousegasemissionsintotalhavecontributed150%oftheobservedwarmingof1.0⁰C,butemissionsofcoolingaerosolshavecounter-actedsomeofthatwarming.mitigationoptionsareunderdevelopmentandnearingcommercializationthatcouldresultinlargevolumesofnon-CO2mitigationandfurtherreducenon-CO2emissions(seeBox4).5.2KEYABATEMENTOPPORTUNITIESPotentialreductionsinnon-CO2gasescancomefromadiversesetofactions,andtheseactionstogetheraggregatetosignificantlevels(Figure13).Technicalpotentialincludestechnologieslikeanaerobicdigestionofmanureintheagriculturalsectorandleakagedetectionandmitigationintheoilandgassector.Asdiscussedabove,someportionofeachnon-CO2Figure13:Non-CO2MitigationTechnicalPotentialbyGas(MtCO2e)in2050.Thisfigureshowspotentialreductionsin2050fromnon-CO2emissionsinmethane,nitrousoxide,andfluorinatedGHGs.Itisconstructedfromabatementcostcurvesusingtechnologieslikeanaerobicdigestionofmanureintheagriculturalsectorandleakagedetectionandmitigationintheoilandgassector.Someabatementtechnologiesarenegativecostandmanycostlessthan$100permetrictonofCO2e.Technicalabatementpotentialismostsignificantformethaneandfluorinatedgases.ResidualMitigation<$100ResidualMitigation<$100ResidualMitigation<$100Mitigation>$100Mitigation>$100Mitigation>$1000200400600800MethaneNitrousoxideFluorinatedgasesMitigationTechnicalPotential(MtCO2equivalent)38THELONG-TERMSTRATEGYOFTHEUNITEDSTATESandnaturalgastypicallyfallintothreecategories:equipmentmodificationsorupgrades;changesinoperationalpractices,includingdirectedinspection,repairandmaintenance(DI&M);andinstallationofnewequipment[35].Abatementmeasuresareavailabletomitigateemissionsassociatedwithavarietyofsystemcomponents,includingcompressors,engines,dehydrators,pneumaticcontrols,pipelines,storagetanks,wells,andothers.Commercially-availablemitigationtechnologiescanalsorecoverandreduceCH4emissionsfromcoalminingoperations.Thesereductiontechnologiesconsistofoneormoreofthefollowingprimarycomponents:adrainageandrecoverysystemtoChange[1].Methaneisprimarilygeneratedbyfossilfuelenergyoperations(oil,gas,andcoal),wasteoperations,andlivestockandagriculturaloperations.Therearecosteffectivemethaneabatementoptionsacrossallthesesectors[36].Figure14shows2050methaneabatementpotentialbysource.Methanemitigationopportunitiesbysectorinclude:•ENERGYSECTORMETHANE.Energysectorfugitivemethaneemissionsresultfromoperationsintheoilandnaturalgassectorandthecoalminingsector.Insomecases,alargeproportionofoilandgasmethaneemissionscomefromasmallnumberofsources.MethanemitigationmeasuresinoilFigure14:2050MethaneAbatementPotentialintheUnitedStates.Thisfigureshowssourcesofmethaneabatementpotentialin2030intheUnitedStates[36].Thismarginalabatementcostcurveindicatesthepriceatwhichmethanemitigationfromvarioussourcesofmethanearecost-effective.Thisfiguredoesnotincludeadditionalabatementthatcanbeachievedbyreducingtheunderlyingactivitiesthatdriveemissions.TheseadditionalreductionsfromactivitydriverchangesareincludedintheGCAMmodelingandreflectedinFigure12.0501001500100200300MethaneEmissionsReductions(MtCO2e)Break-evenPrice($/tCO2e)CoalMiningCroplandsLandfillsLivestockOilandNaturalGasRiceWastewater39THELONG-TERMSTRATEGYOFTHEUNITEDSTATESremoveCH4fromtheundergroundcoalseam,anenduseapplicationforthegasrecoveredfromthedrainagesystem,and/oraventilationairmethane(VAM)recoveryormitigationsystem[35].TheCH4mitigationpotentialfromtheenergysectorat$100/tCO2eis144millionmetrictonsofcarbondioxideequivalent(MtCO2e)orapproximately43%of2030energysectornon-CO2GHGemissionsandremainsanimportantsourceofpotentialmitigationthrough2050.•WASTEMETHANE.LandfillsproduceCH4andotherlandfillgasesthroughthenaturalprocessofbacterialdecompositionoforganicwasteunderanaerobicconditions.Landfillgasesaregeneratedoveraperiodofseveraldecades,withflowsusuallybeginningwithin2yearsofdisposal.Abatementoptionstocontrollandfillemissionsaregroupedintothreecategories:(1)collectionandflaring,(2)landfillgas(LFG)utilizationsystems,and(3)enhancedwastediversionpractices(e.g.,recyclingandreuseprograms)[35].Withinthewastecategory,wastewatertreatmentisthesecondmostimportantsourceofnon-CO2GHGs.Methaneemissionsinwastewatertreatmentcouldbesignificantlyreducedby2050throughcurrentlyavailablemitigationoptions,suchasanaerobicbiomassdigestersandcentralizedwastewatertreatmentfacilities.Improvedoperationalpractices,suchascontrollingdissolvedoxygenlevelsduringtreatmentorlimitingoperatingsystemupsets,canalsohelpreduceN2Oemissionsfromwastewatertreatment[35].TheCH4mitigationpotentialfromthewastesectornon-CO2GHGat$100/tis8MtCO2eor6%oftotal2030wastesectoremissionsandremainsanimportantsourceofpotentialmitigationthrough2050.•LIVESTOCKMETHANE.Emissionsfromlivestockincludeentericfermentationandmanuremanagement.Entericfermentationisanormalmammaliandigestiveprocess,wheregutmicrobesproduceCH4.LivestockmanuremanagementproducesCH4emissionsduringtheanaerobicGLOBALMETHANEPLEDGEInSeptember2021attheMajorEconomiesForum,theUnitedStatesandEuropeanUnionjointlyannouncedtheGlobalMethanePledge.AsofOctober2021,over30supportivecountries,representingwellover30%ofglobalmethaneemissionsand60%ofglobalGDP,hadalreadyjoined—withmanymoreexpected.CountriesjoiningtheGlobalMethanePledgecommittoacollectivegoalofreducingglobalmethaneemissionsbyatleast30%from2020levelsby2030.Theyalsocommittomovingtowardsusinghighest-tierinventorymethodologiestoquantifymethaneemissions,withaparticularfocusonhighemissionsources.DeliveringonthePledgewouldreducewarmingbyatleast0.2°Cby2050.Inaddition,itwouldpreventover200,000prematuredeaths,hundredsofthousandsofasthma-relatedemergencyroomvisits,andover20milliontonsofcroplossesayearby2030byreducingground-levelozonepollutioncausedinpartbymethane.TheUnitedStatesispursuingsignificantmethanereductionsonmultiplefronts.TheLong-TermStrategyanalysisshowsthattheUnitedStatescandoitsparttomeettheglobalgoaloftheGlobalMethanePledgebyreducingdomesticmethaneemissionsbyover30%below2020by2030.Thislevelofreductionwouldavoid11,000prematuredeaths,1,600asthma-relatedemergencyroomvisits,and4.1milliontonsofagriculturallossesperyearintheUnitedStates.40THELONG-TERMSTRATEGYOFTHEUNITEDSTATESNitrousoxidemitigationopportunitiesbysectorinclude:•AGRICULTURALNITROUSOXIDE.Agricultureisthesourceofover82%ofnitrousoxideemissions.MostN2Oisproducedinsoilsbybacteriathroughtheprocessesofnitrificationanddenitrificationwhichoccurwithfertilizerapplication.Itisalsoemittedinlesseramountsfromlivestockwaste,riceproduction,andsoilmanagementsuchasdraining,irrigation,andlandusechange.Nitrousoxideemissionscanbemitigatedbychangingfertilizermanagementpracticestoincreasetheefficiencyofplantuptakeofnitrogen[35].Practicesincludeprecisionagriculture,usingnitrificationinhibitors,andsplittingannualapplicationsintoseasonalapplications.Themitigationpotentialfromtheagriculturesectorat$100/tis8.8MtCO2e,whichis2.5%of2030nitrousoxideemissionsfromagriculture[36]andremainsasmallsourceofmitigationthrough2050.•NITRICANDADIPICACIDPRODUCTION.Nitricacidisaninorganiccompoundusedprimarilytomakesyntheticcommercialfertilizer.Adipicacidisawhitecrystallinesolidusedasafeedstockinthemanufactureofsyntheticfibers,coatings,plastics,urethanefoams,elastomers,andsyntheticlubricants.Theproductionoftheseacidsresultsinnitrousoxideemissionsasaby-product.By2030,abouttwo-thirdsofnitrousoxideemissionsfromthissourcecategoryareprojectedtobefromadipicacidproductiondrivenbyhighdemandgrowthcomparedwithaboutone-thirdfromnitricacidproduction.Abatementmeasuresapplicabletonitricacidarecharacterizedbythepointintheproductionprocesstheyareimplemented,butgenerallyinvolvecatalyticdecompositionofthenitrousoxideby-products[35].Thermaldestructionistheabatementoptionappliedtotheadipicacidproductionprocess.Themitigationpotentialfromnitricandadipicacidproductionat$100/tis17.7MtCO2eor62%oftotalsectoral2030nitrousoxideemissions[36]andremainsanimportantsourceofmitigationthrough2050.decompositionofmanureandN2Oemissionsduringthenitrificationanddenitrificationoftheorganicnitrogencontentinlivestockmanureandurine[35].Withoutalteringunderlyingdemand,themitigationpotentialoflivestockmethaneat$100/tis70MtCO2eor27%of2030livestocknon-CO2GHGemissionsandremainsanimportantsourceofpotentialmitigationthrough2050.•CROPLANDANDRICEPRODUCTIONMETHANE.Theanaerobicdecompositionoforganicmatter(i.e.,decompositionintheabsenceoffreeoxygen)infloodedricefieldsproducesCH4.GHGmitigationscenariosincludeseveralfactorsthatinfluencetheamountofCH4producedandcarbonsequestrationinsoils,includingwatermanagementpracticesandthequantityoforganicmaterialavailabletodecompose[35].Themitigationpotentialfromtheagriculturesectorat$100/tis1.7MtCO2eor1%of2030agriculturalCH4emissions[36].5.2.2NITROUSOXIDENitrousoxide(N2O)isapotentGHGwith298timesmorewarmingpotentialthancarbondioxideandalongatmosphericlifetime(approximately114years).N2Ocomesfromnaturalandanthropogenicsourcesandisremovedfromtheatmospheremainlybyphotolysis(i.e.,breakdownbysunlight)inthestratosphere.IntheUnitedStates,themainanthropogenicsourcesofN2Oareagriculturalsoilmanagement,livestockwastemanagement,mobileandstationaryfossilfuelcombustion,adipicacidproduction,andnitricacidproduction.N2Oisalsoproducednaturallyfromavarietyofbiologicalsourcesinsoilandwater,althoughthisreportonlycoversman-madesourcesonly.Figure15shows2050nitrousoxideabatementpotentialbysource.41THELONG-TERMSTRATEGYOFTHEUNITEDSTATEStoreplaceozone-depletingsubstances(ODS)inrefrigeration,airconditioning,aerosols,firesuppression,andasfoamblowingagents.HFCemissionsreductionsareachievablebypreventingorreducingleaksandtransitioningtotheuseofalternativeswithlowglobalwarmingpotential(GWP).Figure16shows2050fluorinatedGHGabatementpotentialbysource.UndertheAmericanInnovationandManufacturing(AIM)Actof2020,inSeptember2021theEPAfinalizedarulethatphasesdownHFCsthroughanallowanceallocationandtradingprogram.TheAIM5.2.3FLUORINATEDGASESFluorinatedgases(F-GHGs)areanthropogenically-generatedandusedinarangeofapplications.Sometimesreferredtoas“climatesuperpollutants,”theyarehighlypotentGHGs,capableoftrappinghundredstothousandsoftimesmoreheatpermoleculethancarbondioxide.Accordingtothe2021InventoryofU.S.GreenhouseGasEmissionsandSinks[27],mostfluorinatedgasesemittedarehydrofluorocarbons(HFCs).Asubstituteforozone-depletingsubstances,HFCswereinitiallydevelopedFigure15:2050NitrousOxideAbatementPotentialintheUnitedStates.Thisfigureshowssourcesofnitrousoxideabatementpotentialin2050intheUnitedStates.Thismarginalabatementcostcurveindicatesthepriceatwhichnitrousoxidemitigationfromvarioussourcesofarecost-effective.Thisfiguredoesnotincludeabatementassociatedwithareductionoftheunderlyingactivitiesthatdriveemissions.TheseadditionalreductionsfromactivitydriverchangesareincludedintheGCAMmodelingandreflectedinFigure11.05010015001020304050N2OEmissionsReductions(MtCO2e)Break-evenPrice($/tCO2e)LivestockNitricAdipicRiceCroplands42THELONG-TERMSTRATEGYOFTHEUNITEDSTATES5.2.4BLACKCARBONBlackcarbon(soot)isnotaGHG,butapowerfulclimate-warmingaerosol[1]thatisacomponentoffineparticulatematter(PM2.5)thatenterstheatmospherethroughtheincompletecombustionoffossilfuels,biofuels,andbiomass[46].TheArcticisparticularlyvulnerabletowarmingfromblackcarbon.Blackcarbonisalsoalocalairpollutant,contributingtomajorhealthimpactsthatdisproportionatelyaffectlow-incomeandmarginalizedcommunities[47].Transitioningfromfossilfuelcombustionforelectricityandtransport(on-roadandoff-road)tocleaneralternativesiskeytoreducingblackcarbonemissionsintheUnitedStates.Flaringintheoilandgassectorisanadditionalsourceofblackcarbon.TheEPAestimatesthatU.S.blackcarbonemissionshavebeenreducedsignificantlysince2013primarilyduetoreductionsintheroadandoff-roadtransportsectors,largelythroughpoliciesandstrategiestoreducetheemissionsfrommobiledieselengines.Strengtheningparticulatematterstandardsandaddressinglegacydieselvehiclesandemissionsassociatedwithports,includingfromships,portequipment,andtrucks,wouldfurthercontributetomeetingnationalclimate,health,andclimatejusticegoals.Act,alongwiththisrule,providesthedomesticlegalframeworktoimplementthephasedownofHFCsoutlinedintheKigaliAmendmenttotheMontrealProtocol,which124countrieshavejoinedtodate.ThephasedownwilleffectivelydecreasetheproductionandimportofHFCsintheUnitedStatesby85%by2036onthesamestep-downscheduleaslaidoutintheKigaliAmendmentandisexpectedtoresultinreductionsofmorethan4.5billionmetrictonsofcarbondioxide-equivalentby2050.AchievingsignificantHFCreductionsby2050willrelyonathree-prongedapproach.First,phasedowntheproductionandimportofHFCs.Second,addresstheexistingstockofrefrigeratorsandairconditioners,whichalreadycontainHFCsandhavepotentialtoleakintotheatmosphereoverthecomingdecades.Third,deploythenextgenerationoflow-GWPalternativestoexistingHFCs.AdditionalRD&DsupporttoensurenewalternativestoHFCscontinuetoenterthemarketmayalsobeimportant,includingbothnewmoleculesandnewusesforexistingalternatives.Combiningtheseapproaches,themitigationpotentialofHFCsatlessthan$100/tis84MtCO2ewhichis39%oftotal2030sectoralemissionsandremainsanimportantsourceofmitigationthrough2050.43THELONG-TERMSTRATEGYOFTHEUNITEDSTATESFigure16:2050FluorinatedGHGAbatementPotentialintheUnitedStates:ThisfigureshowssourcesoffluorinatedGHGabatementpotentialin2050intheUnitedStates.ThismarginalabatementcostcurveindicatesthepriceatwhichF-GHGmiti-gationfromsourcesofarecost-effective.Thisfiguredoesnotincludeadditionalabatementthatcanbeachievedbyreducingtheunderlyingactivitiesthatdriveemissions.TheseadditionalreductionsfromactivitydriverchangesareincludedintheGCAMmodelingandreflectedinFigure11.0501001504080120160F-GasEmissionsReductions(MtCO2e)Break-evenPrice($/tCO2e)AerosolsAluminumElectricPowerSystemsFireExtinguishersFoamsMagnesiumPhotovolaticsRefrigerationandACSemiconductorsSolvents44THELONG-TERMSTRATEGYOFTHEUNITEDSTATESNON-CO2BREAKTHROUGHTECHNOLOGIES:REDUCINGMETHANEFROMENTERICFERMENTATIONWhilemanylow-costabatementopportunitiesexisttodayfornon-CO2emissions—andarereflectedinthisanalysis—somespecificapplicationsdonothavecurrent,low-costmitigationopportunities.Arenewedfocusonresearchanddevelopmentfortheseremainingnon-CO2emissionprocessescouldpotentiallyprovidesignificantbenefitsaswellasdramaticallylowerthecostsofreductions.Whilenotrequiredtoachieveour2050net-zerogoal,suchadvancescouldprovidevaluableadditionalflexibilityinhowthatgoalcouldbeachieved.Oneexampleofthiskindofpositivebreakthroughmaybeemerging.Withoutatechnologicaladvance,thereislimitedmethaneabatementpotentialfromentericsources—cattle,sheep,andgoats—whichproducemethaneaspartoftheirdigestiveprocess.Whileimprovingproductivitycan,toalimitedextent,helpreducemethaneemissionsperpoundofbeeforgallonofmilk,itdoesnotprovidearoutetomajorreductions.However,recentresearchsuggeststhatnewtechnologiesmightbeabletooffergreatlyincreasedeffectiveness.Newdiscoveriesoflow-costfeedadditivesindicatethepossibilitythatthesewouldunlocklargeadditionalpotentialemissionsreductions.Examplesoftheseadditivesincluderedalgae(Asparagopsis)andacompound,3-Nitrooxypropanol(3-NOP).EPAandotherresearchersarecollectinginformationtoassessthesetechnologies.Asparagopsis,3-NOP,andothertechnologiesthatmayincreasenon-CO2GHGmitigation.ThescienceandeconomicsofAsparagopsisisfarfromsettled,withimportantremainingquestionssurroundingthecoststogrow,harvest,andprocessAsparagopsisintofeed,toassessscalabilitytoproducemarketablequantities(ordirectlysynthesizebromoform);andtoassessthelong-termtoleranceofcattleandtheapplicabilitytodifferentproductionandregulatorysystems.Ifnational-scaledevelopmentsprovetechnicallyandeconomicallyfeasible,Asparagopsiscouldpotentiallydecreaselivestockemissionsbyasmuchas160MtCO2e(60%)in2030.3-NOPhasshownstrongpotentialformethanereductionacrossmultipletrials,withover45peer-reviewedpapersexaminingnumerousaspectsofthepotentialimpactsofthisadditive.3-NOPhasbeenshowntobeeffectiveinreducingentericemissionsbyaboutone-thirdindairycowsandupto70%inbeeffinishingtrialswithoutunacceptableside-effects.Moreinnovationandtestingareneededtofurtherdevelopthesesolutionsandbringthemtomarket.THELONG-TERMSTRATEGYOFTHEUNITEDSTATES4445THELONG-TERMSTRATEGYOFTHEUNITEDSTATES6.1THENECESSITYOFCO2REMOVALTOREACHNET-ZEROEfficiency,electrificationofenduses,decarbonizationoftheelectricitysector,andreductioninnon-CO2emissionsarethemostimportantleversfordecarbonizingtheU.S.economyandwillbetheemphasisoftheoverallstrategytoreachnet-zeroby2050.CHAPTER6:REMOVINGCARBONTHROUGH2050ANDBEYONDFigure17:BalancingEmissionsReductionsandRemovalstoReach2050Net-Zero.Thisfigureshowstherangeofoutcomesformitigationpathwaysaswellasremovalspathwaystoachievenet-zeroby2050.Somesourcesofnon-CO2emissions,andpotentiallysomeCO2emissions,cannotbereducedtozero,andthesemustbebalancedbyCO2removals.CO2removalscanhappenthroughlandsinks,suchasforestgrowthandsoilcarbonsequestration,orthroughcarbondioxideremovaltechnologiessuchasdirectaircaptureorcarboncaptureandsequestrationinindustryorelectricitygeneration.Note:HistoricaldatainthisfigurearefromtheU.S.GHGInventory(2021).0.02.55.0200520202050NetEmissions(GigatonsCO2e)CO2Non-CO2LandSinkCDRNet-GHG46THELONG-TERMSTRATEGYOFTHEUNITEDSTATESThoughtheoverallU.S.landsnetcarbonsinkhasbeenrelativelystableforrecentdecades,thefutureofthatsinkisuncertain[50],andseveralchallengesexisttobolsteringitandexpandingitsignificantly.Substantialforestedlands,includinglargeportionsofourWesternpubliclands,nowhaveolderforestswhichsequesterlessCO2andaremorevulnerabletonaturaldisturbances[51].Moreover,increasedlevelsofdisturbances—fires,insects,diseases,droughts,andstorms—areexpectedinthefuture,alongwithotherpotentialecosystemchangessuchasCO2fertilization,duetoclimatechange.Thesechangingenvironmentalconditionswillalsodictatethefuturedegreeofmitigationandadaptationcapabilitiesandopportunities[53].Thesefactorsarealreadyhavinganimpact:totalcarbonremovalinthelanduse,landusechange,andforestry(LULUCF)sectorhasdecreasedbyapproximately11%since1990[27].Inaddition,U.S.landsincludediverseecosystemswhichcomplicateseffortsatcomprehensiveandtimelydatacollection,aswellasmonitoringandverificationofbaselineemissions,sequestration,andGHGoutcomesofmitigationactivities.Inaddition,thelandbaseisfiniteintermsofitsabilitytocontinuetoprovidefood,fiber,andessentialecosystemandbiodiversityserviceswhilealsosupportingpotentiallyincreasedlevelsofcarbon-beneficialbiomassforenergyproductionandcarbonremovalstrategiesthroughbioenergyandCCS.Inaddition,CO2removalsvianaturalsystemscanbemorevariablethanthoseinothersectorsortechnologies,astheyaresubjecttoreversals,e.g.,fromnaturaldisturbanceslikefires,storms,andpestsorfromindividuallandownerschanginglandmanagementpractices.Also,withrespecttopolicies,U.S.landsareheldandmanagedfordifferentobjectivesbyarangeofdifferentstake-holdersthatoperateunderdifferentlegal,social,andenvironmentalnorms.Achievinglandsectorgoalsnecessitatescoordinationandcooperationwithmillionsofprivatelandowners,privatesectorcorporations,andnon-governmentalorganizations,aswellasTribal,local,state,andfederalgovernmentagencies.Thesechallengesmaybecounterbalanced,atleastinpart,bychangesintheeconomy,policyactions,andinvestments.AchievingsignificantlandcarbonbenefitsHowever,asmentionedinprevioussections,someactivitieswillbedifficulttodecarbonizecompletelyby2050.Becauseofthis,removalsofCO2fromtheatmospherewillbecriticaltoenabletheUnitedStatestoreachnet-zeroby2050andtoachievenetnegativeemissionsthereafter.Thisimpliesanimportantroleforthelandsector,whichcanincreasenaturalcarbondioxideremovalandstoragefromtheatmosphere,aswellasarolefortechnologiesincludingadvancedcarbondioxideremoval(CDR)technologies.Carbondioxideremovaltechnologieswillonlydeliverdesiredsocietalandenvironmentalbenefitsiftheirdeploymentiswell-designedandwell-governed.Figure17showstherangeofoutcomesformitigationpathwaysaswellasremovalspathwaystoachievenet-zeroby2050.6.2MAINTAININGANDENHANCINGCO2REMOVALTHROUGHTHEU.S.LANDCARBONSINKU.S.landsprovidemyriadsocial,economic,andenvironmentalbenefits.TheUnitedStateshas8%oftheworld’sforests(310millionha)and8%ofglobalagriculturallands(400millionha)[48].Theselandsprovideessentialecological,economic,andnon-monetarysocialservices,andwillalsobecriticalinsupportingeconomy-widedecarbonizationoverthenext30yearsandbeyond.Ourlands,andhumanactivitiesonthoselands,emitCO2totheatmospherethroughlandconversion,soildegradation,andforestlossanddegradation,butalsoremoveitviaphotosynthesisandstoreitascarbonintrees,othervegetation,soils,andproducts.Forthelastseveraldecades,U.S.landshavebeenanetcarbonsink,meaningmoreCO2issequesteredthanemittedannuallyfromthelandsector.Thishistorictrendwasdueinparttomillionsofacresshiftingintoforestfromotherusesandtheconservationandcontinuedregrowthoftreesonalreadyforestedlands,muchofwhichhadbeendeforestedbeforetheearly1900s[49].Today’sforestsinkisstillincreasingbutatadecreasingrate[27].In2019,theU.S.landcarbonsinkyieldednetCO2removalsof813MtCO2e,offsettingapproximately12.4%ofeconomy-wideGHGemissions[27].47THELONG-TERMSTRATEGYOFTHEUNITEDSTATES•AGRICULTURALLANDS.TherearepotentialsubstantialGHGmitigationandincreasedremovalopportunitiesonU.S.croplandsandgrasslandsviaactivitiesthatconserveand/orincreasesoilcarbonandemployinnovativelandsmanagementapproachessuchasagroforestry,rotationalgrazing,reducedtillage,residuemanagement,andmore.•BIOENERGY.Biomassisakeycomponentofeffortstodecarbonizetheenergysector,asstudieshaveshownthathigherlevelsofbiomassavailabilityandusecanofferlower-costmitigationthandecarbonizationstrategieswithoutbiomass(e.g.,[60][61]).Bioenergycanbeparticularlyusefulindeepdecarbonizationscenarios,asitcanbeusedtodecarbonizeenergyuseinmultiplesectorsthrougharangeofdifferentenergypathways(e.g.,liquidfuel,biogas,electricity,andhydrogenproduction)anditcanbeusedincombinationwithCCStofurtherreduceGHGemissions[9].Effortsaimedatemployingbiomassuseforenergyshouldincludesafeguardstoensureactualemissionsreductionstotheatmosphereandreflectconsiderationofthemanynon-carbonconsequencesoflarge-scalebiomassproductionanduse(e.g.,competitionwithfoodproductionandbiodiversityandbroaderecosystemimpacts).6.3ASSESSINGPOTENTIALLANDSECTORPATHWAYSTheLTSpathwaysexploredforthisstudyincludevaryingdegreesofprivateandpublicinvestmentinnaturalclimatesolutionsinbothforestryandagriculture,suchasimprovedforestmanagement,firereductionactivities,afforestation,andimprovedagriculturalsoilmanagement.Tobetterreflecttheuncertaintiesassociatedwithestimatingthecomplexcarbondynamicsofdifferentterrestrialecosystemsandrelatedmarketinteractions,andthepotentialextentoflandusechangebetweensectors,theU.S.LULUCFprojectionsthrough2050arepresentedasarange,asseeninFigure18.Thisrangewasdevelopedviaacollaborativemulti-agencyeffortusingdifferentmodelsreflectingalternatemodelingtechniques.by2050andbeyondrequirestargeted,science-basedactionintheneartermandoverthenextseveraldecades.Theseactionsmustnotonlyworktoenhanceourlandcarbonsinkbutalsoensureourlandscontinuetoprovideahostofotherbenefits,includingprovisionofgoods,jobs,ecosystemservices,recreationalandspiritualspaces,andbiodiversitypreservation.Forexample,publicandprivateinvestmentsinnaturalclimatesolutions(e.g.,augmentedfederalprograms,privateentities’involvementinlandconservationandoffsetmarkets)canincreaseacreage,productivity,andoverallhealthofU.S.forestedlands[52][54].Strengtheningexistingandsupportingnewemergingtimbermarkets,especiallyinthefast-growingclimesofSoutheastUnitedStates,canalsohelpmaintainandexpandforestedlands[55].Policies,incentives,andinvestmentsthatcansupportanenhancedsinkthroughactivitiessuchasreforestationandsoilcarbonretentionwillbecentral.Low-orzero-carbonbiomassforbioenergyandBECCSapplicationscanalsocontributetoemissionsreductions.Thesepoliciesandprogramsmustincludesafeguardstominimizeissuessuchaspotentialreversalsandleakagetotheextentpossible,andincludeeffortstobolsterourabilitytomonitor,track,andverifyemissionsreductionsatdifferentscales.Specificareasoffocusinclude:•FORESTS.GHGbenefitsintherelativeneartermcancomefromactivitiessuchasavoidedforestlandconversiontootheruses.Someforestsectoractions,suchaslongerharvestrotationsorincreasedcarbonstorageinharvestedwoodproductsandsubstitutionofmorefossil-intensiveconstructionmaterialswithwoodproducts,canyieldbothnear-andlong-termbenefits[56].ThereareconsiderableopportunitiesforreforestationintheUnitedStates[57],potentiallyupto133millionacres[58].Otheractivitieslikeafforestation,improvedforestmanagementandreducednaturaldisturbances(e.g.,avoidedforestfiresviafueltreatmentssuchasthinningandprescribedfires)canofferincrementalnear-termnetcarbonbenefitsandmayyieldsubstantialbenefitsinthelongterm[59].48THELONG-TERMSTRATEGYOFTHEUNITEDSTATES6.4CO2REMOVALTHROUGHENGINEEREDAPPROACHESInadditiontothelandsectorCO2reductionpotential,technologicalCO2removaloptionscouldbedeployedovercomingdecadestosupportthenet-zeroemissionsgoal.Whilesometechnologiesforsuchactivitiesdoexist,advancedCDRtechnologiesaretodayinvariousstagesofdevelopment.Atthisearlystage,itisdifficulttoestimateexactlywhichcombinationsoftechnologiesmightbemostachievableandappropriateintermsofdeployment,butpotentialstrategiesinclude:TheanalysisisbasedonseveralsectorallandsmodelsincludingtheGlobalTimberModel(GTM),theForestryandAgricultureSectoralOptimizationModelwithGreenhouseGases(FASOM-GHG),threeU.S.ForestServicemodels(theResourcesPlanningAct(RPA)ForestDynamicsmodel,theRPALandUseChangemodel,andtheForestResourceOutlookmodel),andUSDAagriculturalsoilcarbonprojections,toprovidearangeofpotentiallandsinkprojectionsin2050.AsshowninFigure18,thereisasignificantrangeofpossiblelandsectorpathwayswhichcouldenabletheUnitedStatestomeetitsnet-zerogoalby2050.Figure18:LandUse,LandUseChange,andForestryCO2BusinessasUsualandLTSActionProjectionswithUncertaintyRanges.ThereisarangeofpossibleCO2outcomesforboththereferencecaseandtheLong-TermStrategyactioncase.HistoricvaluesarefromtheU.S.GHGInventory[27]andprojectedvaluesarederivedfromarangeoflandsectormodels.Estimatesincludeforestecosystemcarbonpools,harvestedwoodproductscarbonstorage,andlanduseandlanduseconversionfluxesacrosslandtypes.BAURangeNCSActionRange-1,500-1,000-500020052020203020402050LULUCFSink(MtCO2equivalent)49THELONG-TERMSTRATEGYOFTHEUNITEDSTATESbutthepotentialcapacityofCO2mineralizationcouldbequitehigh[62].•OCEAN-BASEDCDR.ThisisaCDRapproachthatremovesdissolvedCO2fromtheocean.Ocean-basedapproachesincludenature-basedapproaches(e.g.,kelpafforestation),engineeredapproaches(e.g.,electrochemicalCO2capturefromseawater),oracombinationofthetwo(e.g.,growingmacroalgaeandsinkingittotheseafloor).Ocean-basedCDRisinearlystagesofresearchanddevelopmentandmeritscloserstudy.Theearlystagesofthesepotentialremovalstrategiespresentsomevisiblechallengestolargescaledeploymentby2050.Forexample,thereiscurrentlynolarge-scaleproofofconceptforDACtechnologyorbioenergywithcarboncaptureandstorage,makingitdifficulttodeterminehowwellthetechnologycanscaleupandwhatthetruecostandadverseimpactsofthetechnologyareatlargescale.Inparallel,sometechnicalobstaclesremain.ResearchtodateindicatesthatDACrequireshighenergyuseforeachmetrictonofCO2removed.Othertechnologies,suchasenhancedmineralization,arestillinnascentstagesofresearchanddevelopment,sothepotentialmagnitudeofreductionsandthetimeframesoverwhichthesetechnologiesmightdeliverreductionsisunknown.Otheruncertaintiesassociatedwithlarge-scaledeploymentofsometechnologieslikeBECCScouldhavebroaderupstreamGHGandotherenvironmentalimplications(e.g.,life-cycleGHGoutcomesofbiomassproduction).Addressingthesechallengesanduncertaintieswillrequireasubstantialandintegratedresearch,development,anddeploymentstrategy.AsonesteptowardsthedevelopmentanddeploymentofnewapproachestoCDR,CongressrecentlycreatedtheCarbonDioxideRemovalTaskForceto“establisharesearch,development,anddemonstrationprogram…totest,validate,orimprovetechnologiesandstrategiestoremovecarbondioxidefromtheatmosphereonalargescale”[63].However,additionalactionswillbeneededtounderstandandinnovateonCDRoptions,toreduceuncertainties,andtoensuresustainableoutcomes.•BIOMASSCARBONREMOVALANDSTORAGE.ThisisacarbondioxideremovalapproachwhereCO2isproducedfromthecombustion,gasification,orotherconversionoflow-orzero-carbonbiomass,forexampletogenerateelectricityorproducehydrogen,andtheresultingCO2emissionsarecapturedandthenstoredinamannerthatpreventsitfromreenteringtheatmosphere.Specifically,thecapturedCO2emissionsarecompressedintoafluidandtransportedtoaspecifiedsite,wheretheyareinjectedintodeep,undergroundgeologicalformations,suchasformeroilandgasreservoirsordeepsalineformationsforlong-termstorage.CDReffortsusingbiomassasaninput,suchasbiomassuseforenergywithCCS,shouldincludesafeguardstoensureactualemissionsreductionstotheatmosphere(e.g.,including,totheextentpossible,robustGHGaccounting),andreflectconsiderationofthemanynon-carbonconsequencesoflarge-scalebiomassproductionanduse(e.g.,competitionwithfoodproductionandbiodiversityandbroaderecosystemimpacts)[61].•DIRECTAIRCAPTUREANDSTORAGE(DACS).ThisisatechnologythatcapturesCO2emissionsdirectlyfromambientair(insteadoffrompointsources,suchaspowerplantsorindustrialfacilities),viasolvent,solidsorbent,ormineralprocesses.ThecapturedCO2istheneithercompressedandsequesteredpermanentlyinageologicalsettingorconvertedintoausablematerialsuchasasyntheticaggregateinconcreteproduction.•ENHANCEDMINERALIZATION.ThisisaCDRapproachthatacceleratesnaturalgeologicprocessesaroundmineralreactionswithCO2fromtheambientair,leadingtopermanentcarbonstoragethroughcarbonaterock.Thereareseveraltypesofmineralizationprocesses:insitu(e.g.,CO2reactionsingeologicformationsunderground),exsitu(e.g.,CO2reactionsthatinvolveextraction,transport,andgrindingofminerals),andsurficial(e.g.,ambientweatheringusingCO2-enrichedfluidsandon-sitemineralslikeminetailings).Researchanddevelopmentforenhancedmineralizationisstillearly,50THELONG-TERMSTRATEGYOFTHEUNITEDSTATES7.1THEBENEFITSFROMATRANSFORMED,NET-ZEROECONOMYBoldandtimelyclimateactiontowardsnet-zerowillhelptheUnitedStatesandtheworldavoidtheworstimpactsofclimatechange—andprovideatransformativeboosttotheU.S.economyandthehealthandwell-beingofallAmericans.Reductionsinfossilfuelcombustionandreductionsinnon-CO2emissionswillimproveairqualityandreducethedangerousrisksofclimatechange.Theexpansionofnewindustrieswillcreatehigh-qualityjobs,maintaineconomiccompetitiveness,andenablesustainable,broad-basedeconomicgrowth.Thebenefitsfromthistransformationarenotconstrainedbypoliticalborders:U.S.actionandambitiousactionfromothercountrieswillhavepositivespillovereffectsincludingdrivingdownthecostofcarbon-freetechnologiesandreducingthecostsofclimateinduceddisastersandconflictsaroundtheworld,particularlyforlowest-incomenationsthatareleastabletoadapt.Inadditiontotheeconomicgains,actiontomeetthenet-zerogoalwill,combinedwithglobalefforts,allowtheUnitedStatestoavoidtheworstimpactsofclimatechange,whicharealreadybeingfelt.Forexample,airpollutionkillsthousandsofpeopleintheUnitedStatesannually[64]andmillionsworldwide,particularlyinthelowest-incomecountries,andongoinginternationalconflictsareexacerbatedbyclimatechange[65].Thelongeractionisdelayed,thefasterthetransitionmustbe,potentiallycausingseveredisruption[66].Moreover,delayincursmoresevereconsequencessuchaschangedweatherregimes(includingnewextremes[67]),highersealevelrise,greateroceanacidification[68],andahigherlikelihoodofreachingcatastrophicdamagesor“tippingpoints”andpotentiallyirreversibleecologicalimpacts.Theseimpactshavehealthandeconomiccostsforall,buttheyareborneunequally,withgreaterconsequencesforlow-incomecountriesgloballyandcommunitiesofcolor,low-incomecommunities,andindigenouscommunitieswithintheUnitedStates[69].Forexample,Blackchildrenare34-41%morelikelytoliveinareaswiththehighestprojectedincreasesinasthmadiagnosesduetoclimate-drivenchangesinparticulateairpollution[68].TheseimpactsareaddressedmorecompletelyintheNationalClimateStrategy[2].CHAPTER7:BENEFITSOFCLIMATEACTIONTHROUGH205051THELONG-TERMSTRATEGYOFTHEUNITEDSTATES7.2IMPROVEMENTSINPUBLICHEALTHClimate-drivenchangesinweather,humanactivity,andnaturalemissionsareallexpectedtoimpactfutureairqualityacrosstheUnitedStates[70].Actingnowonclimatechangeanddecarbonizingourenergysectorwillresultinvastlycleanerair,immediateandlong-termimprovementsinpublichealth,andecologicalbenefitsthroughouttheUnitedStates.Thesebenefitsarisefromseveralsources.REDUCINGGHGSCAUSESREDUCTIONINPOLLUTANTSHARMFULTOHEALTH,WELL-BEING,ANDPRODUCTIVITY.ReducingGHGstonet-zeroby2050willsimultaneouslyreduceotherpollutants,includingparticulatematter(PM),ozoneandPMprecursors,nitrousoxides(NOx),sulfurdioxide(SO2),andotherairtoxics.Thesebenefitswillbemoresignificantincommunitiesoverburdenedbyairpollution.OzoneandPMareairpollutantsthatadverselyaffecthumanhealthandaremonitoredandregulatedwithnationalstandards[71].Humanexposurestothesepollutantshavebeenassociatedwithprematuredeath,hospitaladmissions,andrespiratoryailments,amongothers.Atotalof60,600deathsintheUnitedStatesin2019alonewereattributabletoPMandozoneexposure[73].Theenergysectoraccountsfor80%ofemissionsofNOxand96%ofSO2[70].Astheeconomytransitionstocarbon-freeenergy,reductionsinairpollutionarealsoexpectedtoincreaseproductivityoftheworkforceduetohealthimprovements.Beyondthetraditionalfocusonmortalityimpacts,thereisemergingevidencethatminorhealthimpactsfromairpollutantscanalsoadverselyaffecteducationalattainmentandreducelaborproductivity,e.g.,fewertaskscompletedandfewerhoursworked[74].Suchimprovementswouldbeimportantbecauseclimateprojectionsshowadirectimpactoffutureextremetemperaturesreducinghoursworkedintheeconomy[75].REDUCINGCLIMATECHANGESEVERITYSAVESLIVESANDIMPROVESHEALTH.Climatechangethreatensthehealthandwell-beingofAmericansthroughcatastrophicevents;increasesinheat-relatedillnessesanddeaths;increasesinvector-,food-,andwater-bornedisease;andreducedfoodandwaterquality.Inadditiontoimmediatefatalitiesassociatedwiththeeventsthemselves,extremeweathereventscanexacerbateunderlyingmedicalconditionsanddisruptcriticalhealthcare,resultinginpotentiallylastingconsequences.Furthermore,temperatureincreaseshavebeenlinkedtoincreasesinprematuredeathduetoexposurestobothcoldandheatextremes;additionallyheatexposurehasledtoincreasesinemergencyroomvisitsandhospitaladmissionsforheat-relatedillnessessuchascardiovascularandrespiratoryconditions,kidneyfailure,andpretermbirth,amongothers[77].TherearelargedisparitiesinurbanheatenvironmentsinmanyU.S.citiesthatputlower-incomepeopleandpeopleofcolorathigherriskofheatexposure[79].Changesintemperatureandrainfallpatternshavebeenimplicatedinthespreadofsomeinfectiousdiseasesinsomeareas,includingmosquito-borneZikaandWestNileviruses,bycreatingconditionsthatpromotetheexpansion,abundance,andactivityofcertaindiseasevectors[76][78].Waterbornediseaseshavebeenassociatedwithexcessiverainfallaswellasdroughtconditions.Watertemperatureincreaseshavecontributedtothegrowthoftoxicalgalbloomsandharmfulpathogens(e.g.,SalmonellaandCampylobacter),thepresenceofwhichcanadverselyaffectfoodsecurityandavailability[77].Asforairpollution,thebenefitsofactiontoreduceimpactswillbestrongestincommunitiesthatarehistoricallydisadvantaged,low-income,and/orlackaccesstohealthservicesandpreventionandarethereforemostvulnerabletoclimatechange[68].Forexample,HispanicandLatinoindividualsare25-43%morelikelytocurrentlyliveinareaswiththehighestprojectedlaborhourlossesinweather-exposedindustriesduetoincreasesinhigh-temperaturedays.7.3AVOIDINGCOSTLYCLIMATEIMPACTSAvoidingclimatechangewillprovideimmediateandsustainedbenefitstotheeconomyacrossseveralcategories.GlobalemissionsreductionscansubstantiallyreducethedamagesofclimatechangeintheUnitedStates[80].Oneestimateshowsreducedmonetarydamagesfromasubsetofclimatechangeimpactsof$49billion/yearin2050andupto$388billion/yearin52THELONG-TERMSTRATEGYOFTHEUNITEDSTATES2090totheU.S.economyin1.5°C-compatiblescenarioscomparedtoareferencescenario,fromfactorssuchasfewerdeaths,lessdamagetoinfrastructure,andfewerlostwages.6Similarly,Figure19showsthelargeandincreasingbenefitsthataccrueovertimetotheoveralleconomyfromalow-emissionspathway.7Thisanalysisisonlyalowerboundestimateasitdoesnotincludeacomprehensiveaccountingofallpotentialimpactssuchasotherhealtheffects,effectsonmanagedandunmanagedecosystems,someindirecteffects,andsocialimpacts.6Thetemperatureandradiativeforcingforthetwoscenariosarecalculatedfromthemedianoveranensembleof600MAGICCv7.5.1runsselectedtomatchassessedproxyranges[112].Forthe1.5°Cscenario,globalmeantemperaturereaches1.5°Cin2100withacorrespondingradiativeforcingof2.45Wm-2and3.8°Cin2100withacorrespondingradiativeforcingof7.60Wm-2fortheReferencescenario.Descriptionsoffuturepopulation,GDP,thetransformationofglobaltemperaturechangetocontinentalU.S.temperaturechange,estimationofsealevelrise,andotherparametersandassumptionscanbefoundin[111].Thisframeworkincludesimpactestimatesthatemployavarietyofassumptionsregardingadaptiveresponsestoclimateimpacts.Thegeneraladaptationscenariosconsideredintheanalysesdonotcapturethecomplexissuesthatdriveadaptationdecision-makingatregionalandlocalscales.Adaptationandscenarioassumptionsusedinthisanalysis:HighTideFloodingandTrafficimpactsassumereasonablyanticipatedadaptationmeasures;Rail,Roads,ElectricityTransmissionandDistributionInfrastructure,andCoastalPropertiesassumereactiveadaptation;ExtremeTemperatureMortalityassumescitiesincoolerclimateswilladaptandbecomemoreresilientsimilartopresentdaycitiesinwarmclimates;andOzoneandPM2.5Mortalityuses2011emissionsofco-emittedpollutants.Therestofthesectorsdonotexplicitlymodeladaptation.7Damages,andthereforeavoideddamages,increaseovertimeduetotheincreasingdivergenceinglobalmeantemperaturechangebetweenthetwoscenariosalongwithgrowingpopulations;morevaluablepotentiallyvulnerableinfrastructure;andhighervaluationofavoidedmortality.Figure19:ProjectedAnnualBenefitsofClimateMitigationforSelectYears.Benefitsfromkeepingtoa1.5⁰Ctrajectorygrowsignificantlyovertime.U.S.annualeconomicimpactsforasubsetofsectorsfortheReferenceminus1.5°Cscenario8.Impactspresentedinbillionsof$2017.817U.S.sectorsarerepresentedinthisfigure.Healthimpactsconsistofthefollowingsectors:extremetemperaturemortality,ozoneandPM2.5mortality,valleyfever,wildfirehealtheffects,andsuppressionandsouthwestdusthealtheffects.Coastalimpactsconsistofthefollowingsectors:coastalproperty,hightidefloodingandtraffic,andtropicalstormwinddamages.Infrastructureconsistsofthefollowingsectors:railandroadinfrastructure,electricitydemandandsupply,electricitytransmissionanddistribution,andurbandrainage.Waterresourcesconsistofthefollowingsectors:waterquality,winterrecreation,andinlandflooding.Lastly,thelaborsectorrepresentslostwages.0100200300400205020702090AnnualBenefitsofClimateMitigation(Billion2017$US)WaterResourcesLaborCoastalInfrastructureHealthImpacts53THELONG-TERMSTRATEGYOFTHEUNITEDSTATES7.4ENHANCEDCLIMATESECURITYThereisagrowingbodyofevidencethatclimatechangecanexacerbateconflictandreduceglobalsecurity.Climatechangeisanationalsecuritythreatbecauseitisgloballydestabilizing,changesmilitaryoperatingconditions,anddemandsnewmissions[81].Thismeansthatmitigatingtheriskofclimatechangenotonlydeliversecological,publichealth,andeconomicbenefits,butalsoenhancesnationalandglobalsecurity.Byactingearlyandleadingbyexample,theUnitedStatescanbuildconfidenceinglobaleffortstoreducetheriskofclimatechange[82].Therisksofachangingclimatecanmakeexistingconflictmoreviolent,leadtoinstability,and,throughmoreerraticweather,affecttheabilityofthemilitarytorespondtosecurityconcerns.TheU.S.NationalIntelligenceEstimateassessmentisthat“climatechangewillincreasinglyexacerbateriskstoU.S.nationalsecurityinterestsasthephysicalimpactsincreaseandgeopoliticaltensionsmountabouthowtorespondtothechallenge”[83].ExtremeweatherandconditionsincreasinglyattributedtoclimatechangealreadyimpactU.S.infrastructure,throughtheeffectsofsealevelrise,storms,andwildfire.TheU.S.DepartmentofDefensecallsclimatechangea“topmanagementchallenge”becauseofthethreattooperationalsecurityandtothephysicalinfrastructureofinstallations[84],andfindsthatclimatechangeisreshapingthegeostrategic,operational,andtacticalenvironmentswithsignificantimplicationsforU.S.nationalsecurityanddefense[6].Itcanalsoimpactmilitaryreadinessbydivertingmilitaryassetsandpersonneltoassistwithdisasterrecovery,storms,andwildfireimpact[85].Expertsagreethatclimate-relatedevents(droughts,storms,wildfires,andflooding)arealreadycontributingtoconflict[86].Whilethemainconflictdrivershavebeenrelatedtolowsocioeconomicdevelopment,lowstatecapability,intergroupinequality,andahistoryofconflict,thesedriverscanbeexacerbatedbydisruptionrelatedtoclimatechange[87].Clearcausalrelationshipsbetweenclimatechangeandspecificconflictsarethesubjectofongoingresearch,butdrought,floods,andotherdisastersrelatedtoclimatechangehavebeenassociatedwithlarge-scaledisplacementofpeopleand,insomecases,thishasledtopoliticalinstabilityandconflict.Climatechangeisrelatedtobothshort-termphenomenasuchasextremeweathereventsandlong-termimpactssuchasrisingsealevelsandpersistentdrought.Allofthesecanaffectthelivesandpotentiallythemovementsoflargenumbersofpeopleinawaythatcanincreasestresseswithinandbetweencountries.Tropicalstorms,whichareexpectedtobecomemoresevereasclimatecontinuestochange(andhavealreadybecomemoresevereintheAtlanticBasin),alreadycandisplacelargepopulations.HurricaneKatrina,forexample,traumaticallydisplacedtensofthousandsofpeoplefromthecityofNewOrleans.Inacountrywithlowercapacitytoaddresssuchcrises,asimilareventcouldcreateclimaterefugeesandcauseinstability.Continued,morefrequent,ormoreseveredroughtisalsoanexpectedresultofclimatechange.Inagriculturalsocieties,severedroughtcanexacerbatestresses.DroughtcontributedtothecurrentcivilwarinSyria,causinginternaldestabilizationaswellaspoliticalstressesinneighboringcountriesduetotheresultingrefugeecrisis[88].Theimpactsoflong-termchangingsealevelhavealreadyledtoclimaterefugees,includinginparishesinsouthernLouisiana[89]—andthiscanbedisruptiveacrosstheworld.Forexample,afurthersealevelriseofsixinches(15cm)coulddisplacemillionsfromtheNileDeltainEgypt[90].Instabilityinstrategicallyimportantregions,evenfarfromtheUnitedStates,isanationalsecurityconcern.Societiescanrespondtocriseslikedroughtandwaterstressbystrengtheningpoliticalrelationshipsthatcanbenefitmutualsecurity[91],but,inparticularforvulnerablesocieties,theimpactsofclimatechangemayresultinincreasedconflict.Activelyworkingtomitigateclimatechangealongwithhelpingcommunitiestobuildresilienceandadaptmayreducetherisksoftheseconflicts.54THELONG-TERMSTRATEGYOFTHEUNITEDSTATES7.5BUILDINGASTRONGERU.S.ECONOMYTherevolutioninclimatesolutionshasalreadybegun.Thefastest-growingpowergenerationtechnologiesaresolarandwind,witharecord-setting35GWofdeploymentin2020,accountingforabout80%ofnewcapacity[92].Globally,thezero-emissionsvehicleshareofnewcarsalesisexpectedtorisefrom2%todaytonearly30%by2030[93],withsignificantlyhighernumbersintheUnitedStatesinlinewithreaching50%newcarsales.Intheseandmanyothersectors,thetransitiontocarbonneutralitywillaccelerateforcompatibilitywithinternationalclimatetargets[94],representingrapidlyexpandingnewmarketsintheUnitedStatesandglobally.Theeconomicopportunityofdecarbonizationisimmense.TheUnitedStatesiswell-positionedtoincubatenewinnovatorsandfirms,withawell-trainedworkforceandinstitutionsthathaveenabledgloballeadersininformationtechnology,biotechnology,pharmaceuticals,andotherindustries[95].Moreover,auniqueendowmentofnaturalresourcesmakesgeographicregionsofthecountrywell-suitedtobehubsofawiderangeofcarbon-freeactivities[40].TheUnitedStatescanleadinthecleantechnologiesforthe21stcentury,manufacturingcrucialtechnologieslikebatteries,electricvehicles,andheatpumps,withoutsacrificingcriticalworkerprotectionsorafairdistributionofbenefitsofeconomicactivity.Becauseinnovationiscumulativeandbecausemanyenvironmentaltechnologieshavereturnstoscale,investingearlyinthedevelopmentofnewtechnologies[96]willboostinnovationinclimatesolutionsandmakethepathwaytocarbonneutralitymoreeconomicallyandpoliticallyfeasible[97][98].Smartpublicinvestmentsininnovationstimulateprivateinvestmentandeconomicgrowthandcanhelpestablishnew(andoftenunforeseen)productiveindustriesintheprocess[99][100][101].Onerecentstudyfindssocialreturnsfrominvestmentsinresearchanddevelopmentareasmuchasfourtimeslargerthanprivatereturns[102],andananalysisofdataon16advancedcountriesbetween1980and1998foundthata1%increaseinpublicresearchanddevelopmentinvestmentgeneratedanextra0.17%inlong-runoutput[103].Thebenefitsofacceleratinginnovationwillspillovertoourinternationalpartners,includingtodevelopingcountrieswhichwillbehithardestbyclimatedamagesandcanleastaffordtotakeactionsinresponse.Althoughtheoveralleconomywillbenefitfromthetransitiontocarbonneutrality,certainfossilfuel-dependentsectorsandregionswillhaveamoredifficulttransition.Somecommunitiesarealreadyexperiencingeconomicchallengesfromthedeclinesinfossilfuel-relatedemployment[104],whileothers(predominantlylow-incomecommunities,communitiesofcolor,andindigenouscommunities)areexperiencingdisproportionateimpactsofclimatedisastersandairpollution.AcomprehensivepolicystrategycansupportAmericanworkersandfirmsthroughthetransition,creatinghigh-qualityjobsthroughoutthecountry,includinginhistoricallymarginalizedcommunitiesandinregionsthathavelostmajoremployersandtaxpayers.TheUnitedStatescanleadincleantechnologiesandjobsforthe21stcenturyandiswell-positionedtoincubatenewandinnovativefirms.55THELONG-TERMSTRATEGYOFTHEUNITEDSTATESWithourambitiousNDCtargettocutemissionsinhalformoreby2030,andourgoalfornet-zeroemissionsnolaterthan2050,theUnitedStateshascommittedtosustainedinvestmentinavibrantcleaneconomythatwillpropelglobalclimateactionwhileimprovingsocial,economic,andhealthequityathome.ThisreporthaspresentedtheU.S.Long-TermStrategytoachievetheseambitiousgoals.Theroadaheadto2050containsopportunities,uncertainties,andchallenges.Theopportunitiesareclearandbroadranging,andcollectivelyofferapathwaytoreinventingandreinvigoratingtheAmericaneconomytobeequitable,globallycompetitive,andsupportiveofglobalclimateandsustainabilitygoals.ItwillrelyonAmericaninnovationandpartnershipsacrossallofsociety,includingTribalandsubnationalgovernments;privatesectorbusinesses,industry,andinvestors;non-governmentalorganizationsandculturalinstitutions;universities,researchorganizations,andeducationalinstitutions;andourpeople.Together,wecanmeetthechallengesindevelopinganddeployingnewcleantechnologiesatscale.Wecandiscovernewandcreativewaystoprovidebetterservicesandproductswithlowerclimatefootprints.Andwecandevelop,train,andeducateworkersforproductiveandhealthierworkinnewandfast-growingindustries.Undoubtedly,theU.S.roadmapwillevolveaswelearnmoreaboutthepotentialfornewtechnologiesindiverseapplications,andasnewpolicyplatformsaredevelopedovertime.TheUnitedStatesintendstoregularlyreviewandupdatethisLong-TermStrategyasneededtoconsidersuchdevelopmentsandthelatestscience.GiventherapidpaceofactionintheUnitedStatesandotherleadingcountries,ifothermajoreconomiesadoptsimilarlevelsofambition,theworldcankeepasafer1.5°Cfuturewithinreach.Foritspart,theUnitedStatescurrentlyemits11%ofannualglobalGHGs(secondtoChina,whichemits27%oftheglobaltotal),soeliminatingU.S.emissionsby2050willmakeanimportantdirectcontributiontoreachingoursharedglobalclimategoals.However,othersmuststepupwithbothlong-termandshort-termambition,andmanyarealreadydoingso.Todate,atleast63countriesrepresentingoverhalfcurrentglobalemissionshavecommittedtonet-zeroGHGemissionstargets.Manymore,representingover70%ofglobalemissions,areinCHAPTER8:ACCELERATINGGLOBALCLIMATEPROGRESS56THELONG-TERMSTRATEGYOFTHEUNITEDSTATESdiversestagesofidentifyingandcommittingtosimilarnet-zerotargetsbymid-century[105][106][107].Thesecommitmentsmatter:achievingnear-net-zeroemissionsgloballyby2050willdramaticallyimproveourchancesoflimitingglobalwarmingtonear1.5°C.However,whiletherapidexpansionof2050targetsandlong-termstrategiesisencouraging,commitmentstoactby2030arealsocritical.Countriesrepresentingwelloverhalfoftheglobaleconomy,includingnearlyalltheG7countries,havealreadyputforwardstrong2030NDCs.Leadershipandactionbythesecountrieswillsupportdevelopmentofnewandmoreaffordableclimatetechnologiesandsupportenhanceddiplomaticmomentumtoencourageglobalactiontowardreachingsufficientlevelsofnear-termaction.ButtheUnitedStates,EU,UK,Japan,Canada,RepublicofKorea,SouthAfrica,andotherambitiousmajoreconomiescannotdoitalone.Strong2030NDCswillberequiredbyallG20economiestocutglobalemissionsbyatleast40%by2030.EnhancedactionbyallG20memberstoadopthighambition2030NDCsandmid-centurynet-zerocommitmentscouldreducewarmingbyover0.5°Candkeep1.5°Cwithinreach[108].Globally,thisisthemomentforalltheworld’smajoreconomiestoacttorapidlyreduceemissionstomeetambitious2030NDCtargetsandtodevelopandcommunicatestrategiestoachieveambitious2050net-zerogoals.57REFERENCESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES•[1]IPCC,"ClimateChange2021:ThePhysicalScienceBasis.ContributionofWorkingGroupItotheSixthAssessmentReportoftheIntergovernmentalPanelonClimateChange,"CambridgeUniversityPress,CambridgeUK,2021.https://www.ipcc.ch/report/ar6/wg1/.•[2]UnitedStatesExecutiveOfficeofthePresident,"TheU.S.NationalClimateStrategy,"WashingtonDC,Forthcoming.•[3]UnitedStatesDepartmentofState,"TheUnitedStates’NationallyDeterminedContribution:ReducingGreenhouseGasesintheUnitedStates:A2030EmissionsTarget,"Washington,DC,2021.https://www4.unfccc.int/sites/ndcstaging/PublishedDocuments/United%20States%20of%20America%20First/United%20States%20NDC%20April%2021%202021%20Final.pdf.•[4]UnitedStatesExecutiveOfficeofthePresident,"ExecutiveOrder14008:TacklingtheClimateCrisisatHomeandAbroad,"FederalRegister,Washington,DC,2021.https://www.federalregister.gov/documents/2021/02/01/2021-02177/tackling-the-climate-crisis-at-home-and-abroad.•[5]G7,"CarbisBayG7SummitCommunique,"2021.https://www.whitehouse.gov/briefing-room/statements-releases/2021/06/13/carbis-bay-g7-summit-communique/.•[6]UnitedStatesDepartmentofDefense,OfficeoftheUndersecretaryforPolicy(Strategy,Plans,andCapabilities),"DepartmentofDefenseClimateRiskAnalysis.ReportSubmittedtoNationalSecurityCouncil,"WashingtonDC,2021.•[7]UnitedStatesDepartmentofState,"NationalCommunicationandBiennialReportoftheUnitedStatesofAmerica,"WashingtonDC,2021.•[8]UnitedStatesDepartmentofState,"AdaptationCommunicationoftheUnitedStatesofAmerica,"WashingtonDC,2021.•[9]IPCC,"GlobalWarmingof1.5C,"CambridgeUniversityPress,CambridgeUK,2018.•[10]H.Waisman,M.TorresGunfaus,D.Levai,L.VallejoandA.Deprez,"Acountry-drivenperspectiveonlong-termlow-emissiondevelopmentstrategies,"IDDRI,Paris,2021.https://www.iddri.org/en/publications-and-events/study/country-driven-perspective-long-term-low-emission-development.•[11]K.Levin,D.Rich,K.Ross,T.FransenandC.Elliott,"DesigningandCommunicatingNet-ZeroTargets,"WorldResourcesInstitute,WashingtonDC,2020.www.wri.org/design-net-zero.•[12]UnitedStatesExecutiveOfficeofthePresident,"UnitedStatesMidcenturyStrategy,"Washington,DC,2016.https://unfccc.int/files/focus/long-term_strategies/application/pdf/mid_century_strategy_report-final_red.pdf.•[13]A.Phadke,U.Paliwal,N.Abhyankar,T.McNair,B.Paulos,D.WooleyandR.O'Connell,"2035Electricity,"UniversityofCalifornia,Berkeley,2021.https://www.2035report.com/electricity/.•[14]E.Larson,C.Greig,J.Jenkins,E.Mayfield,A.Pascale,C.Zhang,J.Drossman,R.Williams,S.Pacala,R.Socolow,E.Baik,R.Birdsey,R.Duke,R.Jones,B.Haley,E.Leslie,K.PaustianandA.Swan,"Net-ZeroAmerica:PotentialPathways,Infrastructure,andImpacts,"PrincetonUniversity,PrincetonNJ,2020.https://netzeroamerica.princeton.edu/img/Princeton_NZA_Interim_Report_15_Dec_2020_FINAL.pdf.•[15]R.Newell,D.Raimi,S.VillanuevaandB.Prest,"GlobalEnergyOutlook2021:PathwaysfromParis,"ResourcesfortheFuture,WashingtonDC,2021.https://www.rff.org/publications/reports/global-energy-outlook-2021-pathways-from-paris/.•[16]S.Davis,N.Lewis,M.Shaner,S.Aggarwal,D.Arent,I.Azevedo,S.Benson,T.Bradley,J.Brouwer,Y.Chiang,C.Clack,A.Cohen,S.Doig,J.Edmonds,P.Fennell,C.Field,B.Hannegan,B.Hodge,M.Hoffert,E.Ingersoll,P.Jaramillo,K.Lackner,K.Mach,M.Mastrandrea,J.Ogden,P.Peterson,D.Sanchez,D.Sperling,J.Stagner,J.Trancik,C.J.YangandK.Caldeira,"Net-zeroemissionsenergysystems,"Science,vol.360,no.6396,2018.doi:10.1126/science.aas9793.•[17]InternationalEnergyAgency,"NetZeroby2050:Aroadmapfortheglobalenergysector,"IEA,Paris,2021.iea.li/nzeroadmap.•[18]N.Hultman,L.Clarke,H.McJeon,R.Cui,P.Hansel,E.McGlynn,K.O'Keefe,J.O'Neill,C.WannerandA.Zhao,"ChartinganambitiousU.S.NDCof51%reductionsby2030,"UniversityofMaryland,CollegePark,MD,2021.https://cgs.umd.edu/research-impact/publications/working-paper-charting-ambitious-us-ndc-51-reductions-2030.•[19]N.Hultman,L.Clarke,C.Frisch,K.Kennedy,H.McJeon,T.Cyrs,P.Hansel,P.Bodnar,M.Manion,M.Edwards,R.Cui,C.Bowman,J.Lund,M.Westphal,A.Clapper,J.Jaeger,A.Sen,J.Lou,D.Saha,W.Jaglom,K.Calhoun,K.Igusky,J.deWeese,K.Hammoud,J.C.Altimirano,M.Dennis,C.Henderson,G.ZwickerandJ.O'Neill,"Fusingsubnationalwithnationalclimateactioniscentraltodecarbonization:ThecaseoftheUnitedStates,"NatureCommunications,vol.11,no.5255,2020.doi:10.1038/s41467-020-18903-w.•[20]R.OrvisandM.Mahajan,"A1.5CNDCforclimateleadershipbytheUnitedStates,"2021.https://energyinnovation.org/publication/a-1-5-celsius-pathway-to-climate-leadership-for-the-united-states/.•[21]K.Kennedy,W.Jaglom,N.Hultman,E.Bridgwater,R.Mendell,H.Leslie-Bole,L.Rowland,E.McGlynn,T.Massey-Green,T.Cyrs,L.Clarke,H.McJeon,A.Zhao,J.O'Neill,R.Gasper,J.Feldmann,K.O'Keefe,S.Kennedy,J.ZhaoandH.Kazanecki,"Blueprint2030:AnAll-InClimateStrategyforFaster,MoreDurableEmissionsReductions,"AmericaIsAllIn,WashingtonDC,2021.https://www.americaisallin.com/blueprint-2030/.58REFERENCESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES•[22]J.H.Williams,R.A.Jones,B.Haley,G.Kwok,J.Hargreaves,J.FarbesandM.S.Torn,"Carbon-neutralpathwaysfortheUnitedStates,"AGUAdvances,p.25,2021.doi:10.1029/2020AV000284.•[23]R.Lempert,B.L.Preston,J.Edmonds,L.Clarke,T.Wild,M.Binsted,E.DiringerandB.Townsend,"Pathwaysto2050:AlternativeScenariosforDecarbonizingtheU.S.Economy,"CenterforClimateandEnergySolutions,WashingtonDC,2019.https://www.c2es.org/document/pathways-to-2050-scenarios-for-decarbonizing-the-u-s-economy/.•[24]ElectricPowerResearchInstitute,"PoweringDecarbonization:StrategiesforNet-ZeroCO2emissions,"EPRI,PaloAlto,CA,2021.https://www.lenr-forum.com/attachment/16437-strategies-for-net-zero-co2-emissions-pdf/.•[25]A.Phadke,N.Abhyankar,J.Kersey,T.McNair,U.Paliwal,D.Wooley,O.Ashmoore,R.Orvis,M.O'Boyle,R.O'Connell,U.Agwan,P.Mohanty,P.SreedharanandD.Rajagopal,"2035Transport,"UniversityofCalifornia,Berkeley,2021.https://www.2035report.com/transportation/.•[26]G.Boyd,E.Dutrow,J.SmithandE.Worrell,"AnevaluationofthepotentialtodecarbonizetheU.S.manufacturingsectorby2050,"ACEEE,WashingtonDC,2021.•[27]UnitedStatesEnvironmentalProtectionAgency,"InventoryofU.S.GreenhouseGasEmissionsandSinks:1990–2019,"WashingtonDC,2021.https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2019.•[28]UnitedStatesDepartmentofEnergy,JointGlobalChangeResearchInstitute,"GlobalChangeAnalysisModel,"2021.http://www.globalchange.umd.edu/gcam/.•[29]UnitedStatesDepartmentofEnergy,"OnlineDocumentationforOP-NEMS,"WashingtonDC,2021.https://www.energy.gov/policy/OP-NEMS.•[30]K.Riahi,D.P.vanVuuren,E.Kriegler,J.Edmonds,B.C.O'Neill,S.Fujimori,N.Bauer,K.Calvin,R.Dellink,W.LutzandA.Popp,"TheSharedSocioeconomicPathwaysandtheirenergy,landuse,andgreenhousegasemissionsimplications:Anoverview,"GlobalEnvironmentalChange,vol.42,pp.153-168,2017.https://www.sciencedirect.com/science/article/pii/S0959378016300681.•[31]UnitedStatesEnvironmentalProtectionAgency,GlobalTimberModel(GTM),Washington,DC:EPA,2015.https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=OAP&dirEntryId=198002.•[32]K.G.Austin,J.S.Baker,B.L.Sohngen,C.M.Wade,A.Daigneault,S.B.Ohrel,S.RagnauthandA.Bean,"Theeconomiccostsofplanting,preserving,andmanagingtheworld’sforeststomitigateclimatechange,"NatureCommunications,vol.11,no.5946,1December2020.doi:10.1038/s41467-020-19578-z.•[33]UnitedStatesEnvironmentalProtectionAgency,ForestandAgriculturalSectorOptimizationModelGreenhouseGasVersion(FASOM-GHG),Washington,DC:EPA,2015.https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=82963&Lab=OAP&simplesearch=0&showcriteria=2&sortby=pubDate&searchall=fasom&timstype=.•[34]C.Johnston,J.GuoandJ.Presetemon,"TheForestResourceOutloookModel(FOROM):AtechnicaldocumentsupportingtheForestService2020RPAAssessment,"UnitedStatesDepartmentofAgricultureForestService,AshevilleNC,2021.doi:10.2737/SRS-GTR-254.•[35]UnitedStatesEnvironmentalProtectionAgency,"GlobalNon-CO2GreenhouseGasEmissionProjections&MarginalAbatementCostAnalysis:MethodologyDocumentation,"Washington,DC,2019.https://www.epa.gov/sites/default/files/2019-09/documents/nonco2_methodology_report.pdf.•[36]UnitedStatesEnvironmentalProtectionAgency,"GlobalNon-CO2GreenhouseGasEmissionProjectionsandMitigation2015-2050,"WashingtonDC,2019.https://www.epa.gov/global-mitigation-non-co2-greenhouse-gases.•[37]J.Fuhrman,H.McJeon,P.Patel,S.C.Doney,W.M.ShobeandA.F.Clarens,"Food–energy–waterimplicationsofnegativeemissionstechnologiesina+1.5°Cfuture,"NatureClimateChange,vol.10,pp.920-927,2020.doi:10.1038/s41558-020-0876-z.•[38]M.Muratori,H.Kheshgi,B.Mignone,L.Clarke,H.McJeonandJ.Edmonds,"Carboncaptureandstorageacrossfuelsandsectorsinenergysystemtransformationpathways,"InternationalJournalofGreenhouseGasControl,vol.57,pp.34-41,2017.doi:10.1016/j.ijggc.2016.11.026.•[39]D.Esposito,"StudiesAgree80PercentCleanElectricityby2030WouldSaveLivesandCreateJobsatMinimalCost,"EnergyInnovation:Policy&TechnologyLLC,SanFrancisco,2021.https://energyinnovation.org/wp-content/uploads/2021/09/Studies-Agree-80-Percent-Clean-Electricity-by-2030-Would-Save-Lives-and-Create-Jobs-at-Minimal-Cost.pdf.•[40]NationalAcademiesofSciences,Engineering,andMedicine,"AcceleratingDecarbonizationoftheU.S.EnergySystem,"TheNationalAcademiesPress,WashingtonDC,2021.doi:10.17226/25932.•[41]UnitedStatesDepartmentofEnergy,EnergyInformationAdministration,"MoreU.S.coal-firedpowerplantsaredecommissioningasretirementscontinue,"WashingtonDC,2019.https://www.eia.gov/todayinenergy/detail.php?id=40212.•[42]UnitedStatesDepartmentofEnergy,EnergyInformationAdministration,"Renewablesbecamethesecond-mostprevalentU.S.electricitysourcein2020,"Washington,DC,2021.https://www.eia.gov/todayinenergy/detail.php?id=48896.59REFERENCESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES•[43]UnitedStatesDepartmentofEnergy,EnergyInformationAdministration,"MonthlyEnergyReview,"WashingtonDC,2021.https://www.eia.gov/totalenergy/data/monthly/pdf/sec7_19.pdf.•[44]UnitedStatesDepartmentofEnergy,EnergyInformationAdministration,"ResidentialEnergyConsumptionSurvey,"EIA,Washington,DC,2015.https://www.eia.gov/consumption/residential/data/2015/c&e/pdf/ce1.1.pdf.•[45]UnitedStatesEnvironmentalProtectionAgency,"InventoryofU.S.GreenhouseGasEmissionsandSinks:1990-2019,"UnitedStatesEnvironmentalProtectionAgency,Washington,DC,2021.https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks.•[46]T.C.Bond,S.J.Doherty,D.W.Fahey,P.M.Forster,T.Berntsen,B.J.DeAngelo,M.G.Flanner,S.Ghan,B.KächerandS.Kinne,"Boundingtheroleofblackcarbonintheclimatesystem:Ascientificassessment,"JournalofGeophysicalResearch:Atmospheres,vol.118,no.11,pp.5380-5552,2013.•[47]C.W.Tessum,D.A.Paolella,S.E.Chambliss,J.S.Apte,J.D.HillandJ.D.Marshall,"PM2.5pollutersdisproportionatelyandsystemicallyaffectpeopleofcolorintheUnitedStates,"ScienceAdvances,vol.7,no.18,2021.•[48]FoodandAgricultureOrganizationoftheUnitedNations,"GlobalForestResourcesAssessment,"FoodandAgricultureOrganizationoftheUnitedNations,Rome,2020.http://www.fao.org/forest-resources-assessment/2020/en/.•[49]S.N.Oswalt,W.B.Smith,P.D.MilesandS.A.Pugh,"ForestResourcesoftheUnitedStates,2017:atechnicaldocumentsupportingtheForestService2020RPAAssessment,"U.S.DepartmentofAgriculture,ForestService,Washington,DC,2019.doi:10.2737/WO-GTR-97.•[50]S.B.Ohrel,"PolicyPerspectiveontheRoleofForestSectorModeling,"JournalofForestEconomics,vol.34,no.3-4,pp.187-204,2019.doi:10.1561/112.00000506.•[51]H.Stanke,A.O.Finley,G.M.Domke,A.S.WeedandD.W.MacFarlane,"OverhalfofwesternUnitedStates'mostabundanttreespeciesindecline,"NatureCommunications,vol.12,2021.doi:10.1038/s41467-020-20678-z.•[52]G.M.Domke,S.N.Oswalt,B.F.WaltersandR.S.Morin,"TreeplantinghasthepotentialtoincreasecarbonsequestrationcapacityofforestsintheUnitedStates,"ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica,vol.117,no.40,pp.24649-24651,6October2020.doi:10.1073/pnas.2010840117.•[53]P.R.Shukla,J.Skea,E.C.Buendia,V.Masson-Delmotte,H.O.Pörtner,D.C.Roberts,P.Zhai,R.Slade,S.Connors,R.vanDiemen,M.Ferrat,E.Haughey,S.Luz,S.Neogi,M.Pathak,J.Petzold,J.PortugalPerreira,P.Vyas,E.Huntley,K.Kissick,M.BelkacemiandJ.Malley,"SummaryforPolicymakers.In:ClimateChangeandLand:anIPCCspecialreportonclimatechange,,"IPCC,2019.https://www.ipcc.ch/srccl/chapter/summary-for-policymakers/.•[54]C.M.Wade,J.S.Baker,J.P.Jones,K.G.Austin,Y.Cai,A.B.deHernandez,G.S.Latta,S.B.Ohrel,S.Ragnauth,J.CreasonandB.McCarl,"ProjectingtheImpactofSocioeconomicandPolicyFactorsonGreenhouseGasEmissionsandCarbonSequestrationinU.S.ForestryandAgriculture,"JournalofForestEconomics,vol.37,2022.doi:10.1561/112.00000545.•[55]X.Tian,B.Sohngen,J.Baker,S.OhrelandA.A.Fawcett,"WillU.S.ForestsContinuetoBeaCarbonSink?,"LandEconomics,vol.94,no.1,pp.97-113,2018.doi:10.3368/le.94.1.97.•[56]IPCC,""Chapter9:Forestry"In:ContributionofWorkingGroupIIItotheFourthAssessmentReportoftheIntergovernmentalPanelonClimateChange,"CambridgeUniversityPress,Cambridge,UKandNewYork,NY,2007.https://www.ipcc.ch/report/ar4/wg3/.•[57]S.Cook-Patton,T.Gopalakrishna,A.Daigneault,J.McGuire,S.YeoandJ.Fargione,"LowercostandmorefeasibleoptionstorestoreforestcoverinthecontiguousUnitedStatesforclimatemitigation,"OneEarth,2020.DOI:10.1016/j.oneear.2020.11.013.•[58]ReforestationHub,"https://www.reforestationhub.org/,"2021.•[59]C.VanWinkle,J.Baker,D.Lapidus,S.B.Ohrel,J.Steller,G.LattaandD.Birur,"USforestsectorgreenhousemitigationpotentialandimplicationsfornationallydeterminedcontribution,"RTIPressPublicationNo.OP-0033-1705,ResearchTrianglePark,NC,2017.10.3768/rtipress.2017.op.0033.1705.•[60]IPCC,""Chapter6:Assessingtransformationpathways"In:AR5ClimateChange2014:MitigationofClimateChange,"CambridgeUniversityPress,CambridgeUK,2014.https://www.ipcc.ch/report/ar5/wg3/.•[61]K.Calvin,A.Cowie,G.Berndes,A.Arneth,F.Cherubini,J.Portugal-Pereira,G.Grassi,J.House,F.X.Johnson,A.Popp,M.Rounsevell,R.SladeandP.Smith,"Bioenergyforclimatechangemitigation:Scaleandsustainability,"GCB-Bioenergy,vol.13,no.9,pp.1346-1371,September2021.doi:10.1111/gcbb.12863.•[62]IPCC,"SixthAssessmentReport,ClimateChange2021:ThePhysicalScienceBasis,"CambridgeUniversityPress,Cambridge,UK,2021.https://www.ipcc.ch/report/ar6/wg1/#FullReport.•[63]ConsolidatedAppropriationsAct,2021,DivisionZ,TitleV-CarbonRemoval,Washington,DC,2020.https://rules.house.gov/sites/democrats.rules.house.gov/files/BILLS-116HR133SA-RCP-116-68.pdf.•[64]S.K.Thakrar,S.Balasubramanian,P.J.Adams,I.M.Azevedo,N.Z.Muller,S.N.Pandis,S.Polasky,C.A.PopeIII,A.L.Robinson,J.S.Apte,C.W.Tessum,J.D.MarshallandJ.D.Hill,"ReducingMortalityfromAirPollutionintheUnitedStatesbyTargetingSpecificEmissionSources,"EnvironmentalScience&TechnologyLetters,vol.7,no.9,pp.639-645,2020.https://pubs.acs.org/doi/10.1021/acs.estlett.0c00424.60REFERENCESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES•[65]C.P.Kelley,S.Mohtadi,M.A.Cane,R.SeagerandY.Kushnir,"ClimatechangeintheFertileCrescentandimplicationsoftherecentSyriandrought,"ProceedingsoftheNationalAcademyofSciences,vol.112,no.11,pp.3241-3246,March2015.doi:10.1073/pnas.1421533112.•[66]EnergyInnovation:Policy&TechnologyLLC,"TheCostsofDelay,"SanFrancisco,2021.https://energyinnovation.org/publication/the-costs-of-delay-2/.•[67]E.Fischer,S.SippelandR.Knutti,"Increasingprobabilityofrecord-shatteringclimateextremes,"NatureClimateChange,vol.11,pp.689-695,2021.doi:10.1038/s41558-021-01092-9.•[68]UnitedStatesEnvironmentalProtectionAgency,"ClimateChangeandSocialVulnerabilityintheUnitedStates:AFocusonSixImpacts,"EPA,Washington,DC,2021.http://www.epa.gov/cira/social-vulnerability-report.•[69]N.Watts,M.Amann,N.Arnell,S.Ayeb-Karlsson,J.Beagley,K.BelesovaandM.Boykoff,"The2020ReportoftheLancetCountdownonHealthandClimateChange:RespondingtoConvergingCrises,"TheLancet,vol.397,no.10269,pp.129-170,9January2021.https://www.thelancet.com/article/S0140-6736(20)32290-X/fulltext.•[70]C.G.Nolte,P.D.Dolwick,R.W.Pinder,N.Fann,T.L.Spero,L.W.Horowitz,D.A.Winner,V.NaikandL.H.Ziska,"AirQuality,"inImpacts,Risks,andAdaptationintheUnitedStates:FourthNationalClimateAssessment,VolumeII,WashingtonDC,USGlobalChangeResearchProgram,2018.doi:10.7930/NC4.2018.CH13,pp.512-538.•[71]"CleanAirAct:42U.S.C.§§7401etseq.".•[72]N.Fann,A.Lamson,S.Anenberg,S.Wesson,D.RisleyandB.Hubbell,"EstimatingthenationalpublichealthburdenassociatedwithexposuretoambientPM2.5andozone,"RiskAnalysis,vol.32,no.1,pp.81-95,2012.•[73]HealthEffectsInstitute,"StateofGlobalAir:ASpecialReportonGlobalExposuretoAirPollutionandItsHealthImpacts,"HealthEffectsInstitute,Boston,MA,2020.https://www.stateofglobalair.org/.•[74]J.G.ZivinandM.Neidell,"AirPollution'sHiddenImpacts,"Science,vol.359,no.6371,pp.39-40,5January2018.doi:10.1126/science.aap7711.•[75]UnitedStatesEnvironmentalProtectionAgency,"Multi-ModelFrameworkforQuantitativeSectoralImpactsAnalysis:ATechnicalReportfortheFourthNationalClimateAssessment,"EPA,Washington,DC,2017.https://cfpub.epa.gov/si/si_public_record_Report.cfm?Lab=OAP&dirEntryId=335095.•[76]J.RocklövandR.Dubrow,"Climatechange:anenduringchallengeforvector-bornediseasepreventionandcontrol,"NatureImmunology,vol.21,pp.479-483,2020.doi:10.1038/s41590-020-0648-y.•[77]K.L.Ebi,J.M.Balbus,G.Luber,A.Bole,A.Crimmins,G.E.Glass,S.Saha,M.M.Shimamoto,J.M.TrtanjandJ.L.White-Newsome,"Chapter14:HumanHealth.Impacts,Risks,andAdaptationintheUnitedStates:TheFourthNationalClimateAssessment,VolumeII,"U.S.GlobalChangeResearchProgram,Washington,DC,2018.doi:10.7930/NCA4.2018.CH14.•[78]D.Campbell-Lendrum,Manga,Lucien,M.BagayokoandJ.Sommerfield,"Climatechangeandvector-bornediseases:whataretheimplicationsforpublichealthresearchandpolicy?,"PhilosophicalTransactionsoftheRoyalSocietyofLondon.SeriesB,BiologicalSciences,vol.370,no.1665,5April2015.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4342958/.•[79]B.PlumerandN.Popovich,"HowDecadesofRacistHousingPolicyLeftNeighborhoodsSweltering,"NewYorkTimes,24August2020.https://www.nytimes.com/interactive/2020/08/24/climate/racism-redlining-cities-global-warming.html.•[80]UnitedStatesEnvironmentalProtectionAgency,"TechnicalDocumentationfortheFrameworkforEvaluatingDamagesandImpacts,"WashingtonDC,2021.www.epa.gov/cira/fredi.•[81]UnitedStatesDepartmentofDefense,OfficeoftheUndersecretaryofDefense(AcquisitionandSustainment),"DepartmentofDefenseDraftClimateAdaptationPlan:ReportSubmittedtoNationalClimateTaskForceandFederalChiefSustainabilityOfficer,"DepartmentofDefense,Washington,DC,2021.https://www.sustainability.gov/pdfs/dod-2021-cap.pdf.•[82]R.O.KeohaneandD.G.Victor,"CooperationandDiscordinGlobalClimatePolicy,"NatureClimateChange,vol.6,pp.570-575,2016.doi:10.1038/nclimate2937.•[83]UnitedStatesOfficeoftheDirectorofNationalIntelligence,"NationalIntelligenceEstimate:ClimateChangeandInternationalResponsesIncreasingChallengestoUSNationalSecurityThrough2040,"WashingtonDC,2021.•[84]UnitedStatesArmyCorpsofEngineers,"U.S.DepartmentofDefenseInstallationExposuretoClimateChangeatHomeandAbroad,"WashingtonDC,2021.•[85]UnitedStatesGlobalChangeResearchProgram,"Impacts,Risks,andAdaptationintheUnitedStates:FourthNationalClimateAssessment,"WashingtonDC,2018.https://nca2018.globalchange.gov/.•[86]K.J.Mach,C.M.Kraan,H.Buhaug,M.Burke,J.D.Fearon,C.B.Field,C.S.Hendrix,J.-F.Maystadt,J.O'Loughlin,P.Roessler,J.Scheffran,K.A.SchultzandN.vonUexkull,"Climateasariskfactorforarmedconflict,"Nature,vol.571,pp.193-197,2019.doi:10.1038/s41586-019-1300-6.•[87]F.Gemenne,J.Barnett,W.N.AdgerandG.D.Dabelko,"Climateandsecurity:evidence,emergingrisks,andanewagenda,"ClimaticChange,vol.123,pp.1-9,2014.doi:10.1007/s10584-014-1074-7.61REFERENCESTHELONG-TERMSTRATEGYOFTHEUNITEDSTATES•[88]C.P.Kelley,S.Mohtadi,M.A.Cane,R.SeagerandY.Kushnir,"ClimatechangeintheFertileCrescentandimplicationsoftherecentSyriandrought,"ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica,vol.112,no.11,pp.3241-3246,March22015.doi:10.1073/pnas.1421533112.•[89]K.Pettus,"TheFirstAmericanClimateRefugeesandtheNeedforProactiveRelocation,"TheGeorgeWashingtonUniversityLawReview,vol.87,no.1,pp.172-205,24January2019.https://www.gwlr.org/the-first-american-climate-refugees-and-the-need-for-proactive-relocation/.•[90]I.Al-MarashiandA.Causevic,"NATOandCollectiveEnvironmentalSecurityintheMiddleEastandNorthAfrica,"JournalofStrategicSecurity,vol.13,no.4,pp.28-44,2020.doi:10.5038/1944-0472.13.4.1804.•[91]T.Bohmelt,T.Bernauer,H.Buhaug,N.P.Gleditsch,T.TribaldosandG.Wischnath,"Demand,supply,andrestraint:Determinantsofdomesticwaterconflictandcooperation,"GlobalEnvironmentalChange,vol.29,pp.337-348,2014.doi:10.1016/j.gloenvcha.2013.11.018.•[92]UnitedStatesDepartmentofEnergy,EnergyInformationAdministration,"EIAforecastsrenewableswillbefastestgrowingsourceofelectricitygeneration,"2021.https://www.eia.gov/todayinenergy/detail.php?id=38053.•[93]BloombergNewEnergyFinance,"ElectricVehicleOutlook,"2021.https://about.bnef.com/electric-vehicle-outlook/.•[94]InternationalRenewableEnergyAgency,"GlobalRenewablesOutlook:Energytransformation2050,"IRENA,AbuDhabi,2020.https://www.irena.org/publications/2020/Apr/Global-Renewables-Outlook-2020.•[95]D.Rodrik,""GreenIndustrialPolicy","OxfordReviewofEconomicPolicy,vol.30,no.3,pp.469-491,2014.https://drodrik.scholar.harvard.edu/files/dani-rodrik/files/green_industrial_policy.pdf.•[96]M.Mazzucato,R.KattelandJ.Ryan-Collins,"Challenge-DrivenInnovationPolicy:TowardsaNewPolicyToolkit,"JournalofIndustry,CompetitionandTrade,vol.20,no.2,pp.421-437,2020.doi:10.1007/s10842-019-00329-w.•[97]D.Acemoglu,P.Aghion,L.BursztynandD.Hemous,"TheEnvironmentandDirectedTechnicalChange,"AmericanEconomicReview,vol.102,no.1,pp.131-166,2012.•[98]V.Bosetti,C.Carraro,R.DuvalandM.Tavoni,"Whatshouldweexpectfrominnovation?Amodel-basedassessmentoftheenvironmentalandmitigationcostimplicationsofclimate-relatedR&D,"EnergyEconomics,vol.33,no.6,pp.1313-1320,2011.•[99]A.M.Pereira,"OntheEffectsofPublicInvestmentonPrivateInvestment:WhatCrowdsinWhat?,"PublicFinanceReview,vol.29,no.1,pp.3-25,2001.doi:10.1177/109114210102900101.•[100]J.Bivens,"Thepotentialmacroeconomicbenefitsfromincreasinginfrastructureinvestment,"EconomicPolicyInstitute,Washington,DC,2017.https://www.epi.org/publication/the-potential-macroeconomic-benefits-from-increasing-infrastructure-investment/.•[101]D.C.MoweryandT.Simcoe,"IstheInternetaUSinvention?—aneconomicandtechnologicalhistoryofcomputernetworking,"ResearchPolicy,vol.31,no.8-9,pp.1369-1387,2002.doi:10.1016/S0048-7333(02)00069-0.•[102]B.Lucking,N.BloomandJ.VanReenan,"HaveR&DSpilloversDeclinedinthe21stCentury?,"FiscalStudies,vol.40,no.4,pp.561-590,2020.doi:10.1111/1475-5890.12195.•[103]D.GuellecandB.vanPottelsberghedelaPotterie,"R&DandProductivityGrowth:PanelDataAnalysisof16OECDCountries,"OECDScience,TechnologyandIndustryWorkingPapers,vol.2001,no.2,pp.103-126,2003.•[104]WhiteHouseInteragencyWorkingGrouponCoalandPowerPlantCommunitiesandEconomicRevitalization,"InitialReporttothePresidentonEmpoweringWorkersThroughRevitalizingEnergyCommunities,"UnitedStatesDepartmentofEnergy,Washington,DC,2021.https://netl.doe.gov/IWGInitialReport.•[105]R.Black,K.Cullen,B.Fay,T.Hale,J.Lang,S.MahmoodandS.Smith,"TakingStock:Aglobalassessmentofnetzerotargets,"Energy&ClimateIntelligenceUnit,OxfordUK,2021.https://eciu.net/analysis/reports/2021/taking-stock-assessment-net-zero-targets.•[106]CarbonNeutralityCoalition,"https://carbon-neutrality.global/,"2021.[Online].•[107]ClimateActionTracker,"https://climateactiontracker.org/,"2021.[Online].•[108]C.Fyson,A.Geiges,M.Gidden,J.SroujiandC.Schumer,"ClosingtheGap:TheimpactofG20climatecommitmentsonlimitingglobaltemperatureriseto1.5C,"ClimateAnalytics,WorldResourcesInstitute,2021.•[109]B.Lucking,N.BloomandJ.VanReenan,"HaveR&DSpilloversDeclinedinthe21stCentury?,"FiscalStudies,vol.40,no.4,pp.561-590,2019.•[110]UnitedStatesDepartmentofEnergy,"U.S.DepartmentofEnergyHydrogenProgram,"2021.[Online].www.hydrogen.energy.gov.•[111]UnitedStatesEnvironmentalProtectionAgency,"TechnicalDocumentationfortheFrameworkforEvaluatingDamagesandImpacts,"WashingtonDC,2021.www.epa.gov/cira/fredi.•[112]Z.Nicholls,M.Meinshausen,J.Lewis,M.RojasCorradi,K.Dorheim,T.Gasser,R.Giesekeandet.al.,"ReducedComplexityModelIntercomparisonProjectPhase2:SynthesizingEarthSystemKnowledgeforProbabilisticClimateProjections,"Earth'sFuture,2021.10.1029/2020EF001900.DesignedandPrintedbyGlobalPublishingSolutions(U.S.DepartmentofState/A/GIS/GPS)

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