世界经济论坛-净零到净负：领导者碳去除指南（英）-2021.11-18正式版.docx

WHITE PAPERNOVEMBER 20 2 1In Collaboration with the Global Future Council on Net-Zero Transition and the Alliance of CEO Climate LeadersWORLDECONOMICFORUMNet-ZerotoNet-Negative:AGuideforLeadersonCarbonRemovalCoverandimages:GettyImages,UnsplashContentsForeword3Executivesummary4Intrcxjuction51 Understandcarbonremovalanditslimitations71.1 Wheretoputremovedcarbon?81.2 Wheniscarbonremoved?91.3 Howlongwillcarbonstayremoved?92 Plantoaddressfuture,presentandpastemissions103 Seeksystemicimpact11Conclusion12Annex13Acknowledgements15Contributors16Endnotes17DisclaimerThisdocumentispublishedbytheWorldEnomicForumasacontributiontoaproject,insightareaorinteraction.Thefindings,interpretationsandconclusionsexpressedhereinarearesultofacollaborativeprocessfacilitatedandendorsedbytheWorldEnomicForumbutwhoseresultsdonotnecessarilyrepresenttheviewsoftheWorldEconomicForum,northeentiretyofitsMembers,Partnersorotherstakeholders.©2021WorldEomicForum.Allrightsreserved.Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans,includingphotopyingandrecording,orbyanyinformationstorageandretrievalsystem.November 2021Net-ZerotoNet-Negative:AGuideforLeadersonCarbonRemovalForewordBaroness Bryony Worthington Co-Director, Quadrature Climate Foundation, UnitedKingdomMyles Allen Professor of Geosystem Science. Director, Oxford Net Zero, University of Oxford, United KingdomThreethingsneedtohappentolimitglobalwarmingtosafelevelsinlinewiththeParisAgreement:greenhousegasemissionsneedtobehalvedby2030;net-zeroemissionsmustbeachievedby2050;andglobalemissionswillneedtobecomenet-negativeemissionsafter2050.Firstandforemost,holdingontoastableclimaterequiresadrasticreductionofemissions.Thiswillrequireaneconomictransformationthatreimagineshowweproduceanduseenergyandmostcommodities.Andyet,thatwillstillnotbeenough.Asacomplementtoreductions,carbonremovalsolutionsareneeded.Notonlywillsomeemissions-forexample,inagricultureandheavyindustry-beverydifficulttoreduce,wealsoneedtodrawdowntheEarth'sownemissionsresultingfromthenaturalfeedbackloopsofawarmingplanetandalsoreversethebuild-upofemissionsthathaveaccumulated,andcontinuetoaccumulate,intheatmosphereovertime.Thispaperoffersatimelyguideforbusinessandpolicyleadersdeterminedtoacceleratethetransitiontoaneconomycompatiblewithmaintainingasafeclimate.Itdescribesthelandscapeofexistingcarbonremovalopportunities-fromnature-basedtotechnologicalandhybridsolutions-discussestherelativemeritsandchallengesassociatedwiththese,andrecommendsasetofactionstobeginspeedinguptheirdeploymenttoday.Keyamongthesearecommittingto:learningaboutandinterrogatingtheconceptofcarbonremovalstounderstandthetrade-offs;usingremovalstoaddresscurrent,futureand,importantly,pastemissions;andseekingaleveraged,systemicimpactratherthantakingatactical,least-costapproach.TwooftheWorldEconomicForm,scommunitiescollaboratedtodevelopthispaper:theGlobalFutureCouncil(GFC)onNet-ZeroTransitionandtheAllianceofCEOClimateLeaders'CarbonRemovalsClimateActionGroup.Thiscollaborationalsoproducedapresentation-fromCEOstoCEOs-summarizingthecriticalroleofcarbonremovalandhowcompaniescanuseitbothcrediblyandsmartly.Wearegratefulforthemanycontributionsfrombothofthesegroups,whichalsoyieldedaseriesofarticlespublishedontheForum'sAgendablog,andinparticulartoEliMitchell-LarsonoftheOxfordNetZeroinitiativeandCarbonGapforhisworkindraftingandcollatingmanydiverseperspectives.Thisdiversityhasgeneratedarobustsetofrecommendationsforleaderswhoarereadytodeliverthisimportantpieceoftheclimatepuzzle.ChristianMumenthalerGroupChiefExecutiveOfficer,SwissRe;Co-ChairoftheAllianceofCEOClimateLeaders,SwitzerlandExecutivesummaryPlanningfortheactiveremovalofcarbondioxidefromtheatmospherecoupledwithstorage(CDR),isanintegralpartofanycomprehensivenet-zerostrategy.Thiswhitepaperisaguidefordecision-makerstosomeofthekeychallengesandopportunitiestheymustconsiderwhenengagingwithcarbonremovals.Whentouseremovals?Theuseofcarbonremovalsneedstofollowthemitigationhierarchy:thefirstpriorityisalwaystoreduceoravoidemissionswherepossible.Carbonremovalisappropriateifusedforoneofthreepurposes:1. Compensatingforemissionsthatresultdirectlyfromanactor'sactivitiesbutwhicharedifficultorimpossibletoreduce.2. CompensatingfortheEarth'semissionsresultingfromclimatechangeitself(andhenceindirectlyfrompastorfutureemissions)3. Foractorswithhighambitionsandstrongleadership,goingfurther-achievingnet-negativeemissionstoaddressthelegacyofpastemissions,tacklingthebuildupofcarbondioxideintheatmosphereandbeginningtorestoretheclimateHowshouldleadersengagewithremovals?Wehighlightthreekeyconsiderations:Understandcarbonremovalanditslimitations-itisessentialtoconsiderthecompleteend-to-endcarbonremovalandstoragechallenge.Carbonremovaltechniquescanbroadlybedividedintocategoriesaccordingtothemethodofremoval,andtheformofsubsequentformatofstorage,someofwhichareconsiderednature-based","engineered",orahybridofthetwo.TodeliverthecarbonremovalvolumenecessarytomeettheParisAgreement,allofthesemethodswillneedtobescaledupoverthecomingdecade.Inselectingasafecarbonremovalstrategy,leadersshouldkeepinmind:1. Wheretoputremovedcarbon?Considerthecapacityofcarbonstorageoptionsandhowtheyaredistributedamongtheatmosphere,geosphere(rocks),andbiosphere(marineandterrestrialplantsandsoils).Durablenet-zerostrategiesinvolvebalancingemissionsandremovalslike-for-like(pensatingforongoingfossilfuelusebyreturningcarbondioxidetothegeosphere).2. Wheniscarbonremoved?Notallremovalsarerealizedinstantaneously,andcaremustbetakennottoborrowfromthefuture.3. Howlongwillcarbonstayremoved?Considertheriskofreversaltotheatmosphereofstoredcarbonandanticipateaneedtotransitiontooptionsofferinggreaterpermanenceandlowerrisk.Ensurerobustongoingperformancemonitoring.Plantoaddressfuture,presentandpastemissions-ambitiouscorporateleadersseekingtodeterminethescaleofcarbonremovalrequiredbytheirbusinessesshouldprioritizeunavoidablepresentandfutureemissions,butalsobepreparedtoaddresspastemissionsbacktoanagreeddate.Seeksystemicimpact-finally,whennsideringcarbonremovaloptions,corporationsneedtoreflectontheimpacttheywanttohaveandtheirlevelofambition.Leadersinbusiness,financeandpolicycanactnowtosupportawidearrayofremovalsoptions.Thisincludesbothestablishedmethodsthatarereadyforscaleplusemergingtechniqueswhereurgent,early-stagesupportwilldeliversystemic,far-reachingimpactsbeyondthedecision-maker,sownremit.Howbesttotakeaction?Thebriefcloseswithacalltoaction,undertheoverarchingappealtouseremovalsonlytoaddressemissionsthatcannotbereducedoravoided,prioritizingemissionreductionsaboveremovalsacrossthefullvaluechain.Corporationsengagingwithcarbonremovalmust:1. Buildexpertise,seekadviceandsupportexistingcarbonremovalinitiatives2. Supportemissionreductionsandnaturebasedclimatesolutionsintheirownright3. Seekadiversifiedportfolioofremovalsspanningbiologicalandgeologicaloptions4. Considertheuseofremovalstocompensateforpastemissions5. Prepareforthefuture,includingpotentialliabilityforfutureemissions6. Balanceemissionsfromhigh-durabilitysourceswithhigh-durabilitystorage7. AdvocateforambitiousclimatepoliciesIntroductionToensureasafeclimate,wemustcutcarbondioxideemissionsby50%ormoreby2030,reachnet-zeroemissionsbefore2050andstayatnet-negativeemissionsthroughoutthesecondhalfofthecentury.Thispaperfocusesoncarbondioxideremoval(CDR)anditsroleincomplementingemissionreductionsandreducingthestockofcarbonalreadyintheatmosphere.Achievingnet-zero-removingandstoringgreenhousegasemissionsatthesamerateastheyareemitted-isanimportantwaypointtowardsabsolutezero.Inquantifiableterms:tokeepwarmingbelowtheParisthresholdof2,orpreferably1.50C,massiveyear-on-yearemissionreductionsareneededinadditiontothesaferemovalandstorageof5billionto20billiontonsofCO2fromtheatmosphereeveryyearbymid-century(comparedtotoday'semissionsof40billiontonsCOperyear).FIGRE11.5oCpathwayGlobal CO2 emissions in billion tons per year 50Bsinss-as-sual emissionsNegative emissions-10Net-negative2010202020302040205020602070208020902100Source:AdaptedfromtheIntergovernmentalPanelonClimateChange2018SR15,P1-P4Carbonremovalplaysacriticalroleinenablingtheneutralizationofsomeveryhard-to-abateemissions:(1)achievingnet-zerobymid-centuryintimetokeeppeakwarmingbelowParisthresholds:and(2)deliveringnet-negativeemissionstocooltheplanetandbeginrestoringtheatmosphere.Removalsareacomplementtodeepemissioncuts,notareplacementforthem.Removalsshouldnotdistractfromemissioncutsandarethereforealwaysthefinalstepinamitigationhierarchyandcorporatemitigationstrategy.Therearevariousmethodsofremovingandstoringcarbon,eachwithuniqueadvantages,disadvantages,costsandotherattributes(seeFigure2andtheAnnexforabriefoverview,andtheCDRPrimerforadditionaldetails).Optionsincludenature-basedremovalmethods,manyofwhicharecurrentlyavailableatrelativelylowcosts,andengineeredandhybridsolutions,someofwhich,althoughtheymaystillbeexpensive,arereadytobescaledup,whileothersareatearlierstagesofdevelopment.Thebillionsoftonsofremovalsrequiredcannotbedeliveredbyanyonetechnique;itisthereforenecessarytoexploreandscaleupabroadarrayofremovalmethods.2FIGURE2CarbonremovalmethodsBlue carbon Soil carbon sequestration ForestationOther biomass cartx>n removal and storage (BiCRS) Strip biogenic CO2 from flue gas (X other processes, store it permanently. Includes bioenergy with carbon capture and storage (BECCS).Accelerated weatheringOf natural minerals to react with, and thereby fix, atmospheric CO2Direct air capture and storage (DACS) Filter CO2 directly from the air and store it permanentlyThecarbon-removallandscapespansacrossnature-based,hybridandtechnologicalsolutionsForestationPlant,manageandgrowforeststoremoveandstorecarbonSOilsequestrationIncreasethesoilcart>ncontentthroughchangesinlandmanagement(e.g.no-till)®BlUecarbonIncreasethecart>oncontentofastalzonesandwetlandsthroughchangesinecosystemmanagement(e.g.mangroves),OtheroceanCDR''Othermethodstoenhancetheoceans'abilitytoabsorbcartx>ninecosystemsandoceanchemistry：Biochar'VrProducecharcoalfrombiomassandusee.g.asy'soilamendmentorchemicaladditiveSource:AdaptedfromSwissRe,2020SoNARReDortCarbonremovaltechniquestakemanyforms,whichcanbecategorizedacrdingtothemeansofremovalfromtheatmosphere(e.g.photosynthesispoweredbyorganisms,enhancednaturalgeochemicalprocessessuchasweathering,"engineered'filteringofCOzfromair)andthemeansofsubsequentcarbonstorage(e.g.inorganicmatter,mineralizedforms,geologicalreservoirs,Ihebuiltenvironment,long-livedproducts,oceansedimentsorothersinks).Theseeightbroadcategoriesaboveare-end-to-end"removalandstoragepathways:forexample,bioenergywithcarboncaptureandstorage(BECCS)involvesphotosyntheticcapturecoupledwithstorageingeologicalreservoirs,whereas"forestation"involvesremovalbyandstorageintothesamematerial(theabove-andbelow-groundbiomassoftheforestitself).CarbonremovalsolutionsaresometimesgroupedaccordingtothosethatareconsideredFature-based"versusthosethatare"technological/engineered",orthosethatarea"hybrid'ofthetwo,butthesedistinctionscanbesubjectiveandoccasionallycontroversial(e.g.reforestationisuniversallyconsideredanature-basedsolution,whereasafforestationisnot).Carbonremovalcanserveatleastthreedistinctpurposesindeliveringclimateaction:-Compensatingforhard-to-reduceemissions:Someemissionsaredispersedorverydifficultorexpensivetoeliminate.Removalscancompensatefortheseuntiltechnological,politicalandeconomicconditionsallowfortheirabsolutedecarbonizationsHowever,suchremovalsmustnotcompromiseprogressonabsolutedecarbonizationordetermoreambitiousactionintheshortterm.Thoseemissionsthatareconsidered"hard-to-reduce",andthereforeappropriatetoaddresswithremovals,mustbecontinuallyreassessed.-CompensatefortheEarth'semissionsresultingfromclimatechange:Removalscanalsocounteractincreasedemissionsfromthebiosphereitselfthatresultdirectlyfromhistoricalandfutureemissionshavingwarmedtheplanet,butwhicharedifficulttoattributetoanyspecificactors.-Tacklingthebuild-upofemissionsintheatmosphere:Removalsalsoallowthosepartiesthathavemadethebiggestcontributiontothecarbonbuild-uptoaddresstheirlegacyofcontributingtowarming.Itiscriticaltostoppresent-dayemissionsandreducethestockofcarbonthathasbuiltupintheatmosphere.Onceglobalnet-zeroemissionshavebeenachieved,ongoingglobalnet-negativeemissionswillhavetheeffectofreducingCO2concentrations,coolingtheplanetandrestoringtheclimatetowardsapre-indstrialstate.Despitethecriticalimportanceofremovals,confusionabouttheirappropriateuseabounds.Thispaperdescribessomeoftheissuesthatneedtobeconsideredwhenincludingcarbonremovalinnet-zerostrategiesandoffersavisionofwhatcrediblesupportforremovalslookslike.Thethreekeypillarsthatfollowofferastartingpointforcorporateleaderswhowishtoresponsiblyguidetheirfirms*engagementwithcarbonremoval.UnderstandcarbonremovalanditslimitationsWhatdoesasafeandenduringglobalnet-zerostatelooklike,andhowdoesthisgoalinformtheactionscurrentlyneededtobeginthetransition?- How much room is left to store removed carbon?- How quickly can carbon be removed and stored?-How easy is it for stored carbon to escape back into the atmosphere?Techniquestoremoveandstorecarbonvarywidelyintheirimpacts,benefits,costsandthefundamentalvaluetheydeliver.Thesedifferentattributeshaveimplicationsforthosewhowishtouseremovalstocompensateforfossilfuelemissionstodeliverastableandmaintainablenet-zeroemissionsstate,bothfortheirorganizationandtheplanetasawhole.Threekeycharacteristicsofremovalsarehighlighted,including:1.1Wheretoputremovedcarbon?Thefasterwereduceemissions,thelesscarbonremovalwillbeneeded.Bymid-century,anewjourneyfromnet-zerotoabsolute-zeroemissionswillneedtobewellunderway,aseverytonofcarbonremovedtofirstachieveandthensustainnet-zeroornet-negativeemissionsmustbestoredsomewhere.Atlargevolumes,storagespacewillrun0ut.4Mostreadilyavailablecarbonremovaltechniquestodaystoreremovedcarboninthebiosphere(e.g.vegetationandsoils)orinthegeosphere(e.g.inmineralizedformsaboveorbelowtheEarth,ssurface).Biospherestoragehasthepotentialadvantageofprovidingvaluablenon-carboncobenefits,whilegeospherestorageisbothvastandeffectivelypermanentifimplementedwell.Othercarbon-storageoptionsincludemineralizationattheEarth'ssurface,inthedeepoceanandindeep-seasediments,andinthebuiltenvironment(e.g.structuraltimber)todisplacecarbon-intensivematerialssuchascementandsteel,aswellasinotherlong-livedproducts.Differentcarbon-storageoptionshavedifferentavailablecapacities.Althoughthemaximumpotentialfornature-basedremovalsissubstantialitisordersofmagnitudesmallerthanthegeologicalcarbon-storageresource.Whenanoffsetpurchaserfinancesnature-mediatedremovalsusingcarboncredits,theyimplicitlyconvertfossilcarbon(emissions)intobiologicalcarbon(purchasedremovals).Thisisaone-waynetflowofcarbonfromtheverylar