mitigation of climate change chapter3

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Working Group III Mitigation of Climate Change

Chapter 3

Social, Economic and EthicalConcepts and Methods


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Note:

ThisdocumentisthecopyeditedversionofthefinaldraftReport,dated17December2013,ofthe

Working

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III

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the

IPCC

5th

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"Climate

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2014:

Mitigation

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The Report should be read in conjunction with the document entitled Climate Change 2014:

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ChangestotheunderlyingScientific/TechnicalAssessmenttoensureconsistencywiththeapproved

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FinalDraft Chapter3 IPCCWGIIIAR5

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Chapter: 3

Title: Social,Economic,andEthicalConceptsandMethods

Authors: CLAs: CharlesKolstad,KevinUrama

LAs: JohnBroome,AnnegreteBruvoll,MichelineCario Olvera,Don

Fullerton,ChristianGollier,WilliamMichaelHanemann,Rashid

Hassan,FrankJotzo,MizanR.Khan,LukasMeyer,LuisMundaca

CAs: PhilippeAghion,HuntAllcott,GregorBetz,SeverinBorenstein,

AndrewBrennan,SimonCaney,DanFarber,AdamJaffe,Gunnar

Luderer,AxelOckenfels,DavidPopp

REs: MarleneAttzs,DanielBouille,SnorreKverndokk

CSAs: SheenaKatai,KatyMaher,LindseySarquilla


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Chapter3: Social,Economic,andEthicalConceptsandMethods

Contents

ExecutiveSummary

............................................................................................................................

5

3.1Introduction.................................................................................................................................. 9

3.2Ethicalandsocioeconomicconceptsandprinciples................................................................. 10

3.3Justice,equityandresponsibility................................................................................................ 12

3.3.1Causalandmoralresponsibility.......................................................................................... 12

3.3.2Intergenerationaljusticeandrightsoffuturepeople......................................................... 12

3.3.3Intergenerationaljustice:distributivejustice..................................................................... 13

3.3.4Historicalresponsibilityanddistributivejustice................................................................. 14

3.3.5Intragenerationaljustice:compensatoryjusticeandhistoricalresponsibility..................15

3.3.6Legalconceptsofhistoricalresponsibility.......................................................................... 16

3.3.7Geoengineering,ethics,andjustice.................................................................................... 17

3.4Valuesandwellbeing.................................................................................................................. 18

3.4.1Nonhumanvalues.............................................................................................................. 19

3.4.2Culturalandsocialvalues.................................................................................................... 20

3.4.3Wellbeing............................................................................................................................ 20

3.4.4Aggregationofwellbeing.................................................................................................... 21

3.4.5Lifetimewellbeing............................................................................................................... 21

3.4.6Social

welfare

functions

......................................................................................................

21

3.4.7Valuingpopulation.............................................................................................................. 23

3.5Economics,rights,andduties..................................................................................................... 24

3.5.1Limitsofeconomicsinguidingdecisionmaking................................................................. 25

3.6Aggregationofcostsandbenefits.............................................................................................. 26

3.6.1Aggregatingindividualwellbeing........................................................................................ 26

3.6.1.1Monetaryvalues.......................................................................................................... 27

3.6.2Aggregatingcostsandbenefitsacrosstime........................................................................ 30

3.6.3Co

benefits

and

adverse

side

effects

..................................................................................

36

3.6.3.1Ageneralframeworkforevaluationofcobenefitsandadversesideeffects............36

3.6.3.2Thevaluationofcobenefitsandadversesideeffects................................................ 37

3.6.3.3Thedoubledividendhypothesis.................................................................................. 39

3.7Assessingmethodsofpolicychoice............................................................................................ 40

3.7.1Policyobjectivesandevaluationcriteria............................................................................. 40


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3.7.1.1Economicobjectives.................................................................................................... 41

3.7.1.2Distributionalobjectives.............................................................................................. 42

3.7.1.3Environmentalobjectives............................................................................................ 43

3.7.1.4Institutionalandpoliticalfeasibility............................................................................. 44

3.7.2Analyticalmethodsfordecisionsupport............................................................................ 44

3.7.2.1Quantitativeorientedapproaches.............................................................................. 44

3.7.2.2Qualitativeapproaches................................................................................................ 46

3.8Policyinstrumentsandregulations............................................................................................ 46

3.8.1Economicincentives............................................................................................................ 46

3.8.1.1Emissionstaxesandpermittrading............................................................................. 46

3.8.1.2Subsidies...................................................................................................................... 47

3.8.2Directregulatoryapproaches.............................................................................................. 48

3.8.3Informationprogrammes.................................................................................................... 48

3.8.4Governmentprovisionofpublicgoodsandservices,andprocurement............................48

3.8.5Voluntaryactions................................................................................................................ 48

3.8.6Policyinteractionsandcomplementarity........................................................................... 48

3.8.7Governmentfailureandpolicyfailure................................................................................ 49

3.8.7.1Rentseeking................................................................................................................ 49

3.8.7.2Policyuncertainty........................................................................................................ 49

3.9Metricsofcostsandbenefits..................................................................................................... 50

3.9.1Thedamagesfromclimatechange..................................................................................... 51

3.9.2Aggregateclimatedamages................................................................................................ 54

3.9.3Theaggregatecostsofmitigation....................................................................................... 57

3.9.4Socialcostofcarbon........................................................................................................... 60

3.9.5TheReboundeffect............................................................................................................. 60

3.9.6Greenhousegasemissionsmetrics..................................................................................... 61

3.10Behaviouraleconomicsandculture......................................................................................... 64

3.10.1Behaviouraleconomicsandthecostofemissionsreduction........................................... 65

3.10.1.1Consumerundervaluationofenergycosts................................................................ 65

3.10.1.2Firmbehaviour........................................................................................................... 66

3.10.1.3Nonpriceinterventionstoinducebehaviouralchange............................................ 66

3.10.1.4Altruisticreductionsofcarbonemissions.................................................................. 66

3.10.1.5Humanabilitytounderstandclimatechange............................................................ 67

3.10.2Socialandculturalissues................................................................................................... 68

3.10.2.1Customs..................................................................................................................... 68

3.10.2.2Indigenouspeoples.................................................................................................... 68


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3.10.2.3WomenandClimateChange..................................................................................... 69

3.10.2.4Socialinstitutionsforcollectiveaction...................................................................... 69

3.11Technologicalchange............................................................................................................... 70

3.11.1MarketprovisionofTC...................................................................................................... 70

3.11.2Inducedinnovation........................................................................................................... 70

3.11.3LearningbydoingandotherstructuralmodelsofTC...................................................... 71

3.11.4EndogenousandexogenousTCandgrowth..................................................................... 71

3.11.5PolicymeasuresforinducingR&D.................................................................................... 72

3.11.6Technologytransfer(TT)................................................................................................... 72

3.12Gapsinknowledgeanddata.................................................................................................... 73

3.13FrequentlyAskedQuestions..................................................................................................... 74

References........................................................................................................................................ 76


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ExecutiveSummary

Thisframingchapterdescribesthestrengthsandlimitationsofthemostwidelyusedconceptsand

methodsineconomics,ethics,andothersocialsciencesthatarerelevanttoclimatechange.Italso

providesareferenceresourcefortheotherchaptersintheFifthAssessmentReport(AR5),aswellasfordecisionmakers.

Thesignificanceofthesocialdimensionandtheroleofethicsandeconomicsisunderscoredby

Article2oftheUnitedNationsFrameworkConventiononClimateChange,whichindicatesthatan

ultimateobjectiveoftheConventionistoavoiddangerousanthropogenicinterferencewiththeclimatesystem.Twomainissuesconfrontingsociety(andtheIPCC)are:whatconstitutesdangerous

interferencewiththeclimatesystemandhowtodealwiththatinterference.Determiningwhatis

dangerousisnotamatterfornaturalsciencealone;italsoinvolvesvaluejudgements asubject

matterofthetheoryofvalue,whichistreatedinseveraldisciplines,includingethics,economics,and

othersocialsciences.

Ethicsinvolvesquestionsofjusticeandvalue.Justiceisconcernedwithequityandfairness,and,in

general,withtherightstowhichpeopleareentitled.Valueisamatterofworth,benefit,orgood.

Valuecansometimesbemeasuredquantitatively,forinstance,throughasocialwelfarefunctionor

anindexofhumandevelopment.Economictoolsandmethodscanbeusedinassessingthepositiveandnegativevaluesthatresult

fromparticulardecisions,policies,andmeasures.Theycanalsobeessentialindeterminingthe

mitigationandadaptationactionstobeundertakenaspublicpolicy,aswellastheconsequencesof

differentmitigationandadaptationstrategies.Economictoolsandmethodshavestrengthsand

limitations,bothofwhicharedetailedinthischapter.

Economictoolscanbeusefulindesigningclimatechangemitigationpolicies(veryhighconfidence).Whilethelimitationsofeconomicsandsocialwelfareanalysis,includingcostbenefitanalysis,are

widelydocumented,economicsneverthelessprovidesusefultoolsforassessingtheprosandconsof

taking,ornottaking,actiononclimatechangemitigation,aswellasofadaptationmeasures,inachievingcompetingsocietalgoals.Understandingtheseprosandconscanhelpinmakingpolicy

decisionsonclimatechangemitigationandcaninfluencetheactionstakenbycountries,institutionsandindividuals.[Section3.2]

Mitigationisapublicgood;climatechangeisacaseofthetragedyofthecommons(highconfidence).Effectiveclimatechangemitigationwillnotbeachievedifeachagent(individual,

institutionorcountry)actsindependentlyinitsownselfishinterest,suggestingtheneedforcollectiveaction.Someadaptationactions,ontheotherhand,havecharacteristicsofaprivategood

asbenefitsofactionsmayaccruemoredirectlytotheindividuals,regions,orcountriesthat

undertakethem,atleastintheshortterm.Nevertheless,financingsuchadaptiveactivitiesremains

anissue,particularlyforpoorindividualsandcountries.[3.1]

Analysiscontainedintheliteratureofmoralandpoliticalphilosophycancontributetoresolvingethicalquestionsthatareraisedbyclimatechange(mediumconfidence).Thesequestionsincludehowmuchoverallclimatemitigationisneededtoavoiddangerousinterference,howtheeffortor

costofmitigatingclimatechangeshouldbesharedamongcountriesandbetweenthepresentand

future,howtoaccountforsuchfactorsashistoricalresponsibilityforemissions,andhowtochoose

amongalternativepoliciesformitigationandadaptation.Ethicalissuesofwellbeing,justice,fairness,

andrightsareallinvolved.[3.2,3.3,3.4]

Dutiestopayforsomeclimatedamagescanbegroundedincompensatoryjusticeanddistributivejustice(mediumconfidence).Ifcompensatorydutiestopayforclimatedamagesandadaptationcostsarenotduefromagentswhohaveactedblamelessly,thenprinciplesofcompensatoryjustice

willapplytoonlysomeoftheharmfulemissions[3.3.5].Thisfindingisalsoreflectedinthe


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predominantgloballegalpracticeofattributingliabilityforharmfulemissions[3.3.6].Dutiestopay

forclimatedamagescan,however,alsobegroundedindistributivejustice[3.3.4,3.3.5].

Distributionalweightsmaybeadvisableincostbenefitanalysis(mediumconfidence).Ethicaltheoriesofvaluecommonlyimplythatdistributionalweightsshouldbeappliedtomonetary

measuresofbenefitsandharmswhentheyareaggregatedtoderiveethicalconclusions[3.6.1].Such

weightingcontrastswithmuchofthepracticeofcostbenefitanalysis.

Theuseofatemporaldiscountratehasacrucialimpactontheevaluationofmitigationpoliciesandmeasures.Thesocialdiscountrateistheminimumrateofexpectedsocialreturnthatcompensatesfortheincreasedintergenerationalinequalitiesandthepotentialincreasedcollective

riskthatanactiongenerates.Evenwithdisagreementonthelevelofthediscountrate,aconsensus

favoursusingdecliningriskfreediscountratesoverlongertimehorizons(highconfidence).[3.6.2]

Anappropriatesocialriskfreediscountrateforconsumptionisbetweenoneandthreetimestheanticipatedgrowthrateinrealpercapitaconsumption(mediumconfidence).ThisjudgementisbasedonanapplicationoftheRamseyruleusingtypicalvaluesintheliteratureofnormative

parametersintherule.Ultimately,however,thesearenormativechoices.[3.6.2]

Cobenefitsmaycomplementthedirectbenefitsofmitigation(mediumconfidence).Whilesomedirectbenefitsofmitigationarereductionsinadverseclimatechangeimpacts,cobenefitscan

includeabroadrangeofenvironmental,economic,andsocialeffects,suchasreductionsinlocalair

pollution,lessacidrain,andincreasedenergysecurity.However,whethercobenefitsarenet

positiveornegativeintermsofwellbeing(welfare)canbedifficulttodeterminebecauseof

interactionbetweenclimatepoliciesandpreexistingnonclimatepolicies.Thesameresultsapplyto

adversesideeffects.[3.6.3]

Taxdistortionschangethecostofallabatementpolicies(highconfidence).Acarbontaxoratradableemissionspermitsystemcanexacerbatetaxdistortions,or,insomecases,alleviatethem;

carbontaxorpermitrevenuecanbeusedtomoderateadverseeffectsbycuttingothertaxes.

However,regulationsthatforgorevenue(e.g.,bygivingpermitsaway)implicitlyhavehighersocial

costsbecauseofthetaxinteractioneffect.[3.6.3]

Manydifferentanalyticmethodsareavailableforevaluatingpolicies.Methodsmaybe

quantitative(forexample,costbenefitanalysis,integratedassessmentmodelling,andmulticriteriaanalysis)orqualitative(forexample,sociologicalandparticipatoryapproaches).However,nosingle

bestmethodcanprovideacomprehensiveanalysisofpolicies.Amixofmethodsisoftenneededto

understandthebroadeffects,attributes,tradeoffs,andcomplexitiesofpolicychoices;moreover,policiesoftenaddressmultipleobjectives.[3.7]

Fourmaincriteriaarefrequentlyusedinevaluatingandchoosingamitigationpolicy(mediumconfidence).Theyare:costeffectivenessandeconomicefficiency(excludingenvironmentalbenefits,

butincludingtransactioncosts);environmentaleffectiveness(theextenttowhichtheenvironmental

targetsareachieved);distributionaleffects(impactondifferentsubgroupswithinsociety);andinstitutionalfeasibility,includingpoliticalfeasibility.[3.7.1]

Abroadrangeofpolicyinstrumentsforclimatechangemitigationisavailabletopolicymakers.

Theseinclude:economicincentives,directregulatoryapproaches,informationprogrammes,governmentprovision,andvoluntaryactions.Interactionsbetweenpolicyinstrumentscanenhanceorreducetheeffectivenessandcostofmitigationaction.Economicincentiveswillgenerallybemorecosteffectivethandirectregulatoryinterventions.However,theperformanceandsuitabilityof

policiesdependsonnumerousconditions,includinginstitutionalcapacity,theinfluenceofrent

seeking,andpredictabilityoruncertaintyaboutfuturepolicysettings.Theenablingenvironment

maydifferbetweencountries,includingbetweenlowincomeandhighincomecountries.These

differencescanhaveimplicationsforthesuitabilityandperformanceofpolicyinstruments.[3.8]


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Impactsofextremeeventsmaybemoreimportanteconomicallythanimpactsofaverageclimatechange(highconfidence).Risksassociatedwiththeentireprobabilitydistributionofoutcomesintermsofclimateresponse[WGI]andclimateimpacts[WGII]arerelevanttotheassessmentof

mitigation.Impactsfrommoreextremeclimatechangemaybemoreimportanteconomically(in

termsoftheexpectedvalueofimpacts)thanimpactsofaverageclimatechange,particularlyifthe

damagefromextremeclimatechangeincreasesmorerapidlythantheprobabilityofsuchchange

declines.Thisisimportantineconomicanalysis,wheretheexpectedbenefitofmitigationmaybetradedoffagainstmitigationcosts.[3.9.2]

Impactsfromclimatechangearebothmarketandnonmarket.Marketeffects(wheremarketpricesandquantitiesareobserved)includeimpactsofstormdamageoninfrastructure,tourism,andincreasedenergydemand.Nonmarketeffectsincludemanyecologicalimpacts,aswellaschanged

culturalvalues,noneofwhicharegenerallycapturedthroughmarketprices.Theeconomicmeasure

ofthevalueofeitherkindofimpactiswillingnesstopaytoavoiddamage,whichcanbeestimated

usingmethodsofrevealedpreferenceandstatedpreference.[3.9]

Substitutabilityreducesthesizeofdamagesfromclimatechange(highconfidence).Themonetarydamagefromachangeintheclimatewillbelowerifindividualscaneasilysubstituteforwhatis

damaged,comparedtocaseswheresuchsubstitutionismoredifficult.[3.9]

DamagefunctionsinexistingIntegratedAssessmentModels(IAMs)areoflowreliability(highconfidence).TheeconomicassessmentsofdamagesfromclimatechangeasembodiedinthedamagefunctionsusedbysomeexistingIAMs(thoughnotintheanalysisembodiedinWGIII)are

highlystylizedwithaweakempiricalfoundation.Theempiricalliteratureonmonetizedimpactsis

growingbutremainslimitedandoftengeographicallynarrow.Thissuggeststhatsuchdamage

functionsshouldbeusedwithcautionandthattheremaybesignificantvalueinundertakingresearchtoimprovetheprecisionofdamageestimates.[3.9,3.12]

Negativeprivatecostsofmitigationariseinsomecases,althoughtheyaresometimesoverstatedintheliterature(mediumconfidence).Sometimesmitigationcanlowertheprivatecostsofproductionandthusraiseprofits;forindividuals,mitigationcanraisewellbeing.Expostevidence

suggeststhatsuchnegativecostopportunitiesdoindeedexistbutaresometimesoverstatedin

engineeringanalyses.[3.9]

ExchangeratesbetweenGHGswithdifferentatmosphericlifetimesareverysensitivetothechoiceofemissionmetric.Thechoiceofanemissionmetricdependsonthepotentialapplicationandinvolvesexplicitorimplicitvaluejudgements;noconsensussurroundsthequestionofwhichmetricisbothconceptuallybestandpracticaltoimplement(highconfidence).Intermsofaggregate

mitigationcostsalone,theGlobalWarmingPotential(GWP),witha100yeartimehorizon,may

performsimilarlytoselectedothermetrics(suchasthetimedependentGlobalTemperatureChange

PotentialortheGlobalCostPotential)ofreachingaprescribedclimatetarget;however,variousmetricsmaydiffersignificantlyintermsoftheimplieddistributionofcostsacrosssectors,regions,

andovertime(limitedevidence,mediumagreement).[3.9]

Thebehaviourofenergyusersandproducersexhibitsavarietyofanomalies(highconfidence).Understandingclimatechangeasaphysicalphenomenonwithlinkstosocietalcausesandimpactsis

averycomplexprocess.Tobefullyeffective,theconceptualframeworksandmethodologicaltoolsusedinmitigationassessmentsneedtotakeintoaccountcognitivelimitationsandotherregardingpreferencesthatframetheprocessesofeconomicdecisionmakingbypeopleandfirms.[3.10]

Perceivedfairnesscanfacilitatecooperationamongindividuals(highconfidence).Experimentalevidencesuggeststhatreciprocalbehaviourandperceptionsoffairoutcomesandproceduresfacilitatevoluntarycooperationamongindividualpeopleinprovidingpublicgoods;thisfindingmay

haveimplicationsforthedesignofinternationalagreementstocoordinateclimatechangemitigation.[3.10]


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Socialinstitutionsandculturecanfacilitatemitigationandadaptation(mediumconfidence).Socialinstitutionsandculturecanshapeindividualactionsonmitigationandadaptationandbe

complementarytomoreconventionalmethodsforinducingmitigationandadaptation.Theycan

promotetrustandreciprocityandcontributetotheevolutionofcommonrules.Theyalsoprovide

structuresforactingcollectivelytodealwithcommonchallenges.[3.10]

Technologicalchangethatreducesmitigationcostscanbeencouragedbyinstitutionsand

economicincentives(highconfidence).Aspollutionisnotfullypricedbythemarket,privateindividualsandfirmslackincentivestoinvestsufficientlyinthedevelopmentanduseofemissions

reducingtechnologiesintheabsenceofappropriatepolicyinterventions.Moreover,imperfect

appropriabilityofthebenefitsofinnovationfurtherreducesincentivestodevelopnewtechnologies.[3.11]


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3.1 Introduction

Thisframingchapterhastwoprimarypurposes:toprovideaframeworkforviewingand

understandingthehuman(social)perspectiveonclimatechange,focusingonethicsandeconomics;

andtodefineanddiscusskeyconceptsusedinotherchapters.Itcomplementsthetwootherframingchapters:Chapter2onriskanduncertaintyandChapter4onsustainability.Theaudience

forthischapter(indeedforthisentirevolume)isdecisionmakersatmanydifferentlevels.

Thesignificanceofthesocialdimensionandtheroleofethicsandeconomicsisunderscoredby

Article2oftheUnitedNationsFrameworkConventiononClimateChange(UNFCCC),whichindicatesthattheultimateobjectiveoftheConventionistoavoiddangerousanthropogenicinterferencewith

theclimatesystem.Twomainissuesconfrontingsocietyare:whatconstitutesdangerous

interferencewiththeclimatesystemandhowtodealwiththatinterference.Providinginformation

toanswertheseinterrelatedquestionsisaprimarypurposeoftheIPCC.Althoughnaturalscience

helpsusunderstandhowemissionscanchangetheclimate,and,inturn,generatephysicalimpacts

onecosystems,people,andthephysicalenvironment,determiningwhatisdangerousinvolves

judgingthelevelofadverseconsequences,thestepsnecessarytomitigatetheseconsequences,and

theriskthathumanityiswillingtotolerate.Thesearequestionsrequiringvaluejudgement.

Althougheconomicsisessentialtoevaluatingtheconsequencesandtradeoffsassociatingwith

climatechange,howsocietyinterpretsandvaluesthemisanethicalquestion.

Box 3.1Dangerous interference with the climate system

Article2oftheUnitedNationsFrameworkConventiononClimateChangestatesthattheultimate

objectiveoftheConvention...istoachieve...stabilizationofgreenhousegasconcentrationsintheatmosphereatalevelthatwouldpreventdangerousanthropogenicinterferencewiththe

climatesystem.Judgingwhetherourinterferenceintheclimatesystemisdangerous,i.e.,risks

causingaverybadoutcome,involvestwotasks:estimatingthephysicalconsequencesofour

interferenceandtheirlikelihood;andassessingtheirsignificanceforpeople.Thefirstfallstoscience,

but,astheSynthesisReportoftheIPCCFourthAssessmentReport(AR4)states,Determiningwhat

constitutesdangerousanthropogenicinterferencewiththeclimatesysteminrelationtoArticle2oftheUNFCCCinvolvesvaluejudgements(IPCC,2007,p.42).Valuejudgementsaregovernedbythe

theoryofvalue.Inparticular,valuingriskiscoveredbydecisiontheoryandisdealtwithinChapter2.

Centralquestionsofvaluethatcomewithinthescopeofethics,aswellaseconomicmethodsfor

measuringcertainvaluesareexaminedinthischapter.

Ourdiscussionofethicscentresontwomainconsiderations:justiceandvalue.Justicerequiresthat

peopleandnationsshouldreceivewhattheyaredue,orhavearightto.Forsome,anoutcomeis

justiftheprocessthatgenerateditisjust.Othersviewjusticeintermsoftheactualoutcomes

enjoyedbydifferentpeopleandgroupsandthevaluestheyplaceonthoseoutcomes.Outcome

basedjusticecanrangefrommaximizingeconomicmeasuresofaggregatewelfaretorightsbased

viewsofjustice,forexample,believingthatallcountrieshavearighttocleanair.Differentviews

havebeenexpressedaboutwhatisvaluable.Allvaluesmaybeanthropocentricortheremaybe

nonhumanvalues.Economicanalysiscanhelptoguidepolicyaction,providedthatappropriate,

adequate,andtransparentethicalassumptionsarebuiltintotheeconomicmethods.

Thesignificanceofeconomicsintacklingclimatechangeiswidelyrecognized.Forinstance,central

tothepoliticsoftakingactiononclimatechangearedisagreementsoverhowmuchmitigationthe

worldshouldundertake,andtheeconomiccostsofaction(thecostsofmitigation)andinaction(the

costsofadaptationandresidualdamagefromachangedclimate).Uncertaintyremainsabout(1)the

costsofreducingemissionsofgreenhousegases(GHGs),(2)thedamagecausedbyachangeintheclimate,and(3)thecost,practicality,andeffectivenessofadaptationmeasures(and,potentially,


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geoengineering).Prioritizingactiononclimatechangeoverothersignificantsocialgoalswithmore

neartermpayoffsisparticularlydifficultindevelopingcountries.Becausesocialconcernsand

objectives,suchasthepreservationoftraditionalvalues,cannotalwaysbeeasilyquantifiedor

monetized,economiccostsandbenefitsarenottheonlyinputintodecisionmakingaboutclimate

change.Butevenwherecostsandbenefitscanbequantifiedandmonetized,usingmethodsof

economicanalysistosteersocialactionimplicitlyinvolvessignificantethicalassumptions.This

chapterexplainstheethicalassumptionsthatmustbemadeforeconomicmethods,includingcostbenefitanalysis(CBA),tobevalid,aswellastheethicalassumptionsthatareimplicitlybeingmadewhereeconomicanalysisisusedtoinformapolicychoice.

Theperspectiveofeconomicscanimproveourunderstandingofthechallengesofactingonmitigation.Foranindividualorfirm,mitigationinvolvesrealcosts,whilethebenefitstothemselves

oftheirownmitigationeffortsaresmallandintangible.Thisreducestheincentivesforindividualsor

countriestounilaterallyreduceemissions;freeridingontheactionsofothersisadominant

strategy.Mitigatinggreenhousegas(GHG)emissionsisapublicgood,whichinhibitsmitigation.Thisalsopartlyexplainsthefailureofnationstoagreeonhowtosolvetheproblem.

Incontrast,adaptationtendsnottosufferfromfreeriding.Gainstoclimatechangefrom

adaptation,suchasplantingmoreheattolerantcrops,aremainlyrealizedbythepartieswhoincur

thecosts.AssociatedexternalitiestendtobemorelocalizedandcontemporaneousthanforGHG

mitigation.Fromapublicgoodsperspective,globalcoordinationmaybelessimportantformany

formsofadaptationthanformitigation.Forautonomousadaptationinparticular,thegainsfrom

adaptationaccruetothepartyincurringthecost.However,publicadaptationrequireslocalor

regionalcoordination.Financialandotherconstraintsmayrestrictthepursuitofattractive

adaptationopportunities,particularlyindevelopingcountriesandforpoorerindividuals.

Thischapteraddressestwoquestions:whatshouldbedoneaboutactiontomitigateclimatechange

(anormativeissue)andhowtheworldworksinthemultifacetedcontextofclimatechange(a

descriptiveorpositiveissue).Typically,ethicsdealswithnormativequestionsandeconomicswith

descriptiveornormativequestions.Descriptivequestionsareprimarilyvalueneutral,forexample,howfirmshavereactedtocapandtradeprogrammestolimitemissions,orhowsocietieshavedealt

withresponsibilityforactionsthatwerenotknowntobeharmfulwhentheyweretaken.Normative

questionsuseeconomicsandethicstodecidewhatshouldbedone,forexample,determiningtheappropriatelevelofburdensharingamongcountriesforcurrentandfuturemitigation.Inmakingdecisionsaboutissueswithnormativedimensions,itisimportanttounderstandtheimplicitassumptionsinvolved.Mostnormativeanalysesofsolutionstotheclimateproblemimplicitly

involvecontestableethicalassumptions.

Thischapterdoesnotattempttoanswerethicalquestions,butratherprovidespolicymakerswith

thetools(concepts,principles,arguments,andmethods)tomakedecisions.Summarizingtheroleof

economicsandethicsinclimatechangeinasinglechapternecessitatesseveralcaveats.Whilerecognizingtheimportanceofcertainnoneconomicsocialdimensionsoftheclimatechange

problemandsolutionstoit,spacelimitationsandourmandatenecessitatedfocusingprimarilyon

ethicsandeconomics.Furthermore,manyoftheissuesraisedhavealreadybeenaddressedin

previousIPCCassessments,particularlyAR2(publishedin1995).Inthepast,ethicshasreceivedless

attentionthaneconomics,althoughaspectsofbothsubjectsarecoveredinAR2.TheliteraturereviewedhereincludespreAR4literatureinordertoprovideamorecomprehensiveunderstanding

oftheconceptsandmethods.WehighlightnewdevelopmentsinthefieldsincethelastIPCCassessmentin2007.

3.2 Ethicalandsocioeconomicconceptsandprinciples

WhenacountryemitsGHGs,itsemissionscauseharmaroundtheglobe.Thecountryitselfsuffersonlyapartoftheharmitcauses.Itisthereforerarelyintheinterestsofasinglecountrytoreduce


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itsownemissions,eventhoughareductioninglobalemissionscouldbenefiteverycountry.Thatis

tosay,theproblemofclimatechangeisatragedyofthecommons(Hardin,1968).Effective

mitigationofclimatechangewillnotbeachievedifeachpersonorcountryactsindependentlyinits

owninterest.

Consequently,effortsarecontinuingtoreacheffectiveinternationalagreementonmitigation.They

raiseanethicalquestionthatiswidelyrecognizedandmuchdebated,namely,burdensharingor

effortsharing.Howshouldtheburdenofmitigatingclimatechangebedividedamongcountries?Itraisesdifficultissuesofjustice,fairness,andrights,allofwhichliewithinthesphereofethics.

Burdensharingisonlyoneoftheethicalquestionsthatclimatechangeraises.1Anotheristhe

questionofhowmuchoverallmitigationshouldtakeplace.UNFCCCsetstheaimofavoiding

dangerousanthropogenicinterferencewiththeclimatesystem,andjudgingwhatisdangerousis

partlyataskforethics(seeBox3.1).Besidesjustice,fairness,andrights,acentralconcernofethics

isvalue.Judgementsofvalueunderliethequestionofwhatinterferencewiththeclimatesystemwouldbedangerous.

Indeed,ethicaljudgementsofvalueunderliealmosteverydecisionthatisconnectedwithclimate

change,includingdecisionsmadebyindividuals,publicandprivateorganizations,governments,and

groupingsofgovernments.Someofthesedecisionsaredeliberatelyaimedatmitigatingclimate

changeoradaptingtoit.Manyothersinfluencetheprogressofclimatechangeoritsimpacts,sotheyneedtotakeclimatechangeintoaccount.

Ethicsmaybebroadlydividedintotwobranches:justiceandvalue.Justiceisconcernedwith

ensuringthatpeoplegetwhatisduetothem.Ifjusticerequiresthatapersonshouldnotbetreated

inaparticularwayuprootedfromherhomebyclimatechange,forexamplethenthepersonhas

arightnottobetreatedthatway.Justiceandrightsarecorrelativeconcepts.Ontheotherhand,criteriaofvalueareconcernedwithimprovingtheworld:makingitabetterplace.Synonymsforvalueinthiscontextaregood,goodnessandbenefit.Antonymsarebad,harmandcost.

Toseethedifferencebetweenjusticeandvalue,thinkofatransferofwealthmadebyarichcountry

toapoorone.Thismaybeanactofrestitution.Forexample,itmaybeintendedtocompensatethepoorcountryforharmthathasbeendonetoitbytherichcountrysemissionsofGHG.Inthiscase,

thetransferismadeongroundsofjustice.Thepaymentistakentobeduetothepoorcountry,andtosatisfyarightthatthepoorcountryhastocompensation.Alternatively,therichcountrymay

makethetransfertosupportthepoorcountrysmitigationeffort,becausethisisbeneficialto

peopleinthepoorcountry,therichcountry,andelsewhere.Therichcountrymaynotbelievethepoorcountryhasarighttothesupport,butmakesthepaymentsimplybecauseitdoesgood.This

transferismadeongroundsofvalue.Whatwouldbegoodtodoisnotnecessarilyrequiredasa

matterofjustice.Justiceisconcernedwithwhatpeopleareentitledtoasamatteroftheirrights.

Thedivisionbetweenjusticeandvalueiscontestedwithinmoralphilosophy,andsoisthenatureof

theinteractionbetweenthetwo.Someauthorstreatjusticeasinviolable(Nozick,1974):justicesets

limitsonwhatwemaydoandwemaypromotevalueonlywithinthoselimits.Anoppositeview

calledteleologicalbyRawls(1971)isthattherightdecisiontomakeisalwaysdeterminedbythe

valueofthealternatives,sojusticehasnorole.Butdespitethecomplexityoftheirrelationshipand

thecontroversiesitraises,thedivisionbetweenjusticeandvalueprovidesausefulbasisfororganizingthediscussionofethicalconceptsandprinciples.Wehaveadopteditinthischapter:sections3.3 and3.4 coverjusticeandvalue,respectively.Onetopicappearsinbothsections

becauseitbridgesthedivide:thistopicisdistributivejusticeviewedonewayandthevalueof

equalityviewedtheother.Section3.3.7 ongeoengineeringisalsoinanintermediateposition

1AsurveyoftheethicsofclimatechangeisGardiner(2004),pp.555600.


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becauseitraisesethicalissuesofbothsorts.Section3.6 explainshowsomeethicalvaluescanbe

measuredbyeconomicmethodsofvaluation.Section3.5 describesthescopeandlimitationsof

thesemethods.Latersectionsdeveloptheconceptsandmethodsofeconomicsinmoredetail.

PracticalwaystotakeaccountofdifferentvaluesinpolicymakingarediscussedinSection3.7.1 .

3.3 Justice,equityandresponsibility

Justice,fairness,equity,andresponsibilityareimportantininternationalclimatenegotiations,as

wellasinclimaterelatedpoliticaldecisionmakingwithincountriesandforindividuals.

Inthissectionweexaminedistributivejustice,which,forthepurposeofthisreview,isabout

outcomes,andproceduraljusticeorthewayinwhichoutcomesarebroughtabout.Wealsodiscuss

compensationfordamageandhistoricresponsibilityforharm.Inthecontextofclimatechange,

considerationsofjustice,equity,andresponsibilityconcerntherelationsbetweenindividuals,as

wellasgroupsofindividuals(e.g.,countries),bothatasinglepointintimeandacrosstime.

Accordingly,wedistinguishintragenerationalfromintergenerationaljustice.Theliteraturehasnoagreementonacorrectanswertothequestion,whatisjust?Weindicatewhereopinionsdiffer.

3.3.1 Causalandmoralresponsibility

Fromtheperspectiveofcountriesratherthanindividualsorgroupsofindividuals,historicemissionscanhelpdeterminecausalresponsibilityforclimatechange(denElzenetal.,2005;Lamarqueetal.,

2010;Hhneetal.,2011).Manydevelopedcountriesareexpectedtosufferrelativelymodestphysicaldamageandsomeareevenexpectedtorealizebenefitsfromfutureclimatechange(see

Tol,2002a;b).Ontheotherhand,somedevelopingcountriesbearlesscausalresponsibility,but

couldsuffersignificantphysicaldamagefromclimatechange(IPCC,2007WGIIAR4SPM).This

asymmetrygivesrisetothefollowingquestionsofjusticeandmoralresponsibility:doconsiderations

ofjusticeprovideguidanceindeterminingtheappropriatelevelofpresentandfutureglobal

emissions;thedistributionofemissionsamongthosepresentlyliving;andtheroleofhistorical

emissionsindistributingglobalobligations?Thequestionalsoarisesofwhomightbeconsideredmorallyresponsibleforachievingjustice,and,thus,abearerofdutiestowardsothers.Thequestion

ofmoralresponsibilityisalsokeytodeterminingwhetheranyoneowescompensationforthe

damagecausedbyemissions.

3.3.2 IntergenerationaljusticeandrightsoffuturepeopleIntergenerationaljusticeencompassessomeofthemoraldutiesowedbypresenttofuturepeople

andtherightsthatfuturepeopleholdagainstpresentpeople.2Alegitimateacknowledgmentthat

futureorpastgenerationshaverightsrelativetopresentgenerationsisindicativeofabroad

understandingofjustice.3Whilejusticeconsiderationssounderstoodarerelevant,theycannot

coverallourconcernsregardingfutureandpastpeople,includingthecontinuedexistenceof

humankindandwithahighlevelofwellbeing.4

Whatdutiesdopresentgenerationsowefuturegenerationsgiventhatcurrentemissionswillaffect

theirqualityoflife?Somejusticetheoristshaveofferedthefollowingargumenttojustifyacapon

2Inthephilosophical literature,justicebetweengenerationstypicallyreferstotherelationsbetweenpeople

whoselifetimesdonotoverlap(Barry,1977).Incontrast,justicebetweenagegroupsreferstotherelations

ofpeoplewhoselifetimesdooverlap(LaslettandFishkin,1992).SeealsoGardiner(2011),pp.14548.

3SeeRawls(1971,1999),Barry(1977),SikoraandBarry(1978),Partridge(1981),Parfit(1986),Birnbacher

(1988),andHeyd(1992).

4SeeBaier(1981),DeShalit(1995),Meyer(2005),andforAfricanphilosophicalperspectivessee,Behrens

(2012).SeeSection3.4 onthewellbeingoffuturepeople.


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emissions(Shue,1993,1999;Caney,2006a;MeyerandRoser,2009;Wolf,2009).Iffuturepeoples

basicrightsincludetherighttosurvival,health,andsubsistence,thesebasicrightsarelikelytobe

violatedwhentemperaturesriseaboveacertainlevel.However,currentlylivingpeoplecanslowthe

riseintemperaturebylimitingtheiremissionsatareasonablecosttothemselves.Therefore,living

peopleshouldreducetheiremissionsinordertofulfiltheirminimaldutiesofjusticetofuture

generations.Normativetheoristsdisputethestandardoflivingthatcorrespondstopeoplesbasic

rights(Page,2007;Huseby,2010).Alsoindisputeiswhatlevelofharmimposedonfuturepeopleismorallyobjectionable.Somearguethatcurrentlylivingpeoplewrongfullyharmfuturepeopleiftheycausethemtohavealowerlevelofwellbeingthantheirown(e.g.,Barry,1999);othersthat

currentlylivingpeopleowefuturepeopleadecentlevelofwellbeing,whichmightbelowerthan

theirown(Wolf,2009).Thisargumentraisesobjectionsongroundsofjusticesinceitpresupposes

thatpresentpeoplecanviolatetherightsoffuturepeople,andthattheprotectionoffuture

peoplesrightsispracticallyrelevantforhowpresentpeopleoughttoact.

Sometheoristsclaimthatfuturepeoplecannotholdrightsagainstpresentpeople,owingtospecialfeaturesofintergenerationalrelations:someclaimthatfuturepeoplecannothaverightsbecause

theycannotexercisethemtoday(Steiner,1983;Wellman,1995,ch.4).Otherspointoutthat

interactionbetweennoncontemporariesisimpossible(Barry,1977,pp.243244,1989,p.189).

However,somejusticetheoristsarguethatneithertheabilityto,northepossibilityof,mutual

interactionarenecessaryinattributingrightstopeople(Barry,1989;Buchanan,2004).Theyholdthatrightsareattributedtobeingswhoseinterestsareimportantenoughtojustifyimposingduties

onothers.

Themainsourceofscepticismabouttherightsoffuturepeopleandthedutiesweowethemisthe

socallednonidentityproblem.Actionswetaketoreduceouremissionswillchangepeopleswayoflifeandsoaffectnewpeopleborn.Theyaltertheidentitiesoffuturepeople.Consequently,our

emissionsdonotmakefuturepeopleworseoffthantheywouldotherwisehavebeen,sincethose

futurepeoplewouldnotexistifwetookactiontopreventouremissions.Thismakesithardtoclaim

thatouremissionsharmfuturepeople,orthatweoweittothemasamatteroftheirrightstoreduceouremissions.5

Itisoftenarguedthatthenonidentityproblemcanbeovercome(McMahan,1998;Shiffrin,1999;

Kumar,2003;Meyer,2003;Harman,2004;Reiman,2007;Shue,2010).Inanycase,dutiesofjusticedonotincludeallthemoralconcernsweshouldhaveforfuturepeople.Otherconcernsaremattersofvalueratherthanjustice,andtheytoocanbeunderstoodinsuchawaythattheyarenotaffectedbythenonidentityproblem.TheyareconsideredinSection3.4 .

Ifpresentpeoplehaveadutytoprotectfuturepeoplesbasicrights,thisdutyiscomplicatedby

uncertainty.Presentpeoplesactionsoromissionsdonotnecessarilyviolatefuturepeoplesrights;

theycreateariskoftheirrightsbeingviolated(Bell,2011).Todeterminewhatcurrentlyliving

peopleowefuturepeople,onehastoweighsuchuncertainconsequencesagainstotherconsequencesoftheiractions,includingthecertainorlikelyviolationoftherightsofcurrentlyliving

people(Oberdiek,2012;Temkin,2012).Thisisimportantinassessingmanylongtermpolicies,

includingongeoengineering(seeSection3.3.7 ),thatriskviolatingtherightsofmanygenerations

ofpeople(Crutzen,2006;Schneider,2008;Victoretal.,2009;Baer,2010;Ott,2012).

3.3.3 Intergenerationaljustice:distributivejusticeSupposethataglobalemissionsceilingthatisintergenerationallyjusthasbeendetermined

(recognizingthataceilingisnottheonlywaytodealwithclimatechange),thequestionthenarises

ofhowtheceilingoughttobedividedamongstates(and,ultimately,theirindividualmembers)

5ForanoverviewoftheissueseeMeyer(2010).SeealsoSchwartz(1978),Parfit(1986),andHeyd(1992).Fora

differentperspectiveseePerrett(2003).


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(Jamieson,2001;Singer,2002;MeyerandRoser,2006;Caney,2006a).Distributingemissionpermits

isawayofarrivingatagloballyjustdivision.Amongthewidelydiscussedviewsondistributive

justicearestrictegalitarianism(Temkin,1993),indirectegalitarianviewsincludingprioritarianism

(Parfit,1997),andsufficientarianism(Frankfurt,1999).Strictegalitarianismholdsthatequalityhas

valueinitself.Prioritarianismgivesgreaterweighttoapersonswellbeingthelesswelloffsheis,as

describedinSection3.4 .Sufficientarianismrecommendsthateveryoneshouldbeabletoenjoya

particularlevelofwellbeing.Forexample,twooptionscanhelpapplyprioritarianismtothedistributionoffreelyallocatedand

globallytradeableemissionpermits.Thefirstistoignorethedistributionofothergoods.Thenstrict

egalitarianismorprioritarianismwillrequireemissionpermitstobedistributedequally,sincetheywillhaveonepriceandarethusequivalenttoincome.Thesecondistotakeintoaccountthe

unequaldistributionofotherassets.Sincepeopleinthedevelopingworldarelesswelloffthanin

thedevelopedworld,strictegalitarianismorprioritarianismwouldrequiremostorallpermitstogo

tothedevelopingworld.However,itisquestionablewhetheritisappropriatetobringtheoveralldistributionofgoodsclosertotheprioritarianidealthroughthedistributionofjustonegood(Wolff

anddeShalit,2007;Caney,2009,2012).

3.3.4 Historicalresponsibilityanddistributivejustice

HistoricalresponsibilityforclimatechangedependsoncountriescontributionstothestockofGHGs.TheUNFCCCreferstocommonbutdifferentiatedresponsibilitiesamongcountriesofthe

world.6Thisissometimestakentoimplythatcurrentandhistoricalcausalresponsibilityforclimate

changeshouldplayaroleindeterminingtheobligationsofdifferentcountriesinreducingemissions

andpayingforadaptationmeasuresglobally(Rajamani,2000;Riveetal.,2006;Friman,2007).

Anumberofobjectionshavebeenraisedagainsttheviewthathistoricalemissionsshouldplayarole(see,e.g.,Gosseries,2004;Caney,2005;MeyerandRoser,2006;PosnerandWeisbach,2010).First,

ascurrentlylivingpeoplehadnoinfluenceovertheactionsoftheirancestors,theycannotbeheld

responsibleforthem.Second,previouslylivingpeoplemaybeexcusedfromresponsibilityonthe

groundsthattheycouldnotbeexpectedtoknowthattheiremissionswouldhaveharmfulconsequences.Thirdly,presentindividualswiththeirparticularidentitiesarenotworseorbetteroff

asaresultoftheemissiongeneratingactivitiesofearliergenerationsbecause,owingtothenon

identityproblem,theywouldnotexistastheindividualstheyarehadearliergenerationsnotacted

astheydid.

Fromtheperspectiveofdistributivejustice,however,theseobjectionsneednotpreventpastemissionsandtheirconsequencesbeingtakenintoaccount(MeyerandRoser,2010;Meyer,2013).

Ifweareonlyconcernedwiththedistributionofbenefitsfromemissiongeneratingactivitiesduring

anindividualslifespan,weshouldincludethebenefitspresentpeoplehavereceivedfromtheirown

emissiongeneratingactivities.Furthermore,presentpeoplehavebenefitedsincebirthor

conceptionfrompastpeoplesemissionproducingactions.Theyarethereforebetteroffasaresult

ofpastemissions,andanyprincipleofdistributivejusticeshouldtakethatintoaccount.Some

suggestthattakingaccountoftheconsequencesofsomepastemissionsinthiswayshouldnotbe

subjecttotheobjectionsmentionedinthepreviousparagraph(seeShue,2010).Otherconcepts

associatedwithhistoricalresponsibilityarediscussedinChapter4.

6Specifically,Article3oftheUNFCCCincludesthesentence:ThePartiesshouldprotecttheclimatesystemfor

thebenefitofpresentandfuturegenerationsofhumankind,onthebasisofequityandinaccordancewith

theircommonbutdifferentiatedresponsibilitiesandrespectivecapabilities.


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3.3.5 Intragenerationaljustice:compensatoryjusticeandhistoricalresponsibilityDothosewhosufferdisproportionatelyfromtheconsequencesofclimatechangehavejustclaimsto

compensationagainstthemainperpetratorsorbeneficiariesofclimatechange(see,e.g.,Neumayer,

2000;Gosseries,2004;Caney,2006b)?

Onewayofdistinguishingcompensatoryfromdistributiveclaimsistorelyontheideaofajustbaselinedistributionthatisdeterminedbyacriterionofdistributivejustice.Underthisapproach,

compensationforclimatedamageandadaptationcostsisowedonlybypeoplewhohaveacted

wrongfullyaccordingtonormativetheory(Feinberg,1984;Coleman,1992;McKinnon,2011).Other

deviationsfromthebaselinemaywarrantredistributivemeasurestoredressundeservedbenefitsor

harms,butnotascompensation.Somedeviations,suchasthosethatresultfromfreechoice,may

notcallforanyredistributionatall.

Thedutytomakecompensatorypayments(Gosseries,2004;Caney,2006b)mayfallonthosewho

emitorbenefitfromwrongfulemissionsorwhobelongtoacommunitythatproducedsuch

emissions.Accordingly,threeprinciplesofcompensatoryjusticehavebeensuggested:thepolluterpaysprinciple(PPP),thebeneficiarypaysprinciple(BPP),andthecommunitypaysprinciple(CPP)

(MeyerandRoser,2010;Meyer,2013).Noneofthethreemeasuresisgenerallyaccepted,though

thePPPismorewidelyacceptedthantheothers.ThePPPrequirestheemittertopaycompensation

iftheagentemittedmorethanitsfairshare(determinedasoutlinedinSection3.3.2 )anditeitherknew,orcouldreasonablybeexpectedtoknow,thatitsemissionswereharmful.Thevictimshould

beabletoshowthattheemissionseithermadethevictimworseoffthanbeforeorpushed belowa

specifiedthresholdofharm,orboth.

TherighttocompensatorypaymentsforwrongfulemissionsunderPPPhasatleastthreebasic

limitations.TwohavealreadybeenmentionedinSection3.3.4 .Emissionsthattookplacewhileit

waspermissibletobeignorantofclimatechange(whenpeopleneitherdidknownorcouldbereasonablybeexpectedtoknowabouttheharmfulconsequencesofemissions)maybeexcused

(Gosseries,2004,pp.3941).SeealsoSection3.3.6 .Thenonidentityproblem(seeSection3.3.2 )

impliesthatearlieremissionsdonotharmmanyofthepeoplewhocomeintoexistencelater.

Potentialdutybearersmaybedeadandcannotthereforehaveadutytosupplycompensatory

measures.ItmaythereforebedifficulttousePPPinascribingcompensatorydutiesandidentifying

wrongedpersons.Thefirstandthirdlimitationsrestricttheassignmentofdutiesofcompensationtocurrentlylivingpeoplefortheirmostrecentemissions,eventhoughmanymorepeoplearecausally

responsiblefortheharmfuleffectsofclimatechange.Forfutureemissions,thethirdlimitationcould

beovercomethroughaclimatechangecompensationfundintowhichagentspayleviesforimposing

theriskofharmonfuturepeople(McKinnon,2011).

AccordingtoBPP,apersonwhoiswrongfullybetteroffrelativetoajustbaselineisrequiredto

compensatethosewhoareworseoff.Pastemissionsbenefitsomeandimposecostsonothers.If

currentlylivingpeopleacceptthebenefitsofwrongfulpastemissions,ithasbeenarguedthatthey

takeonsomeofthepastwrongdoersdutyofcompensation(Gosseries,2004).Also,wehaveaduty

tocondemninjustice,whichmayentailadutynottobenefitfromaninjusticethatcausesharmtoothers(Butt,2007).However,BPPisopentoatleasttwoobjections.First,dutiesofcompensation

ariseonlyfrompastemissionsthathavebenefitedpresentpeople;nocompensationisowedfor

otherpastemissions.Second,ifvoluntaryacceptanceofbenefitsisaconditionoftheirgivingriseto

compensatoryduties,thebearersofthedutiesmustbeabletoforgothebenefitsinquestionata

reasonablecost.

UnderCPP,moraldutiescanbeattributedtopeopleasmembersofgroupswhoseidentitypersists

overgenerations(DeShalit,1995;Thompson,2009).Theprincipleclaimsthatmembersofa

community,includingacountry,canhavecollectiveresponsibilityforthewrongfulactionsofother

pastandpresentmembersofthecommunity,eventhoughtheyarenotmorallyorcausally

responsibleforthoseactions(Thompson,2001;Miller,2004;Meyer,2005).Itisamatterofdebate


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underwhatconditionspresentpeoplecanbesaidtohaveinheritedcompensatoryduties.Although

CPPpurportstoovercometheproblemthatapollutermightbedead,itcanjustifycompensatory

measuresonlyforemissionsthataremadewrongfully.Itdoesnotcoveremissionscausedbyagents

whowerepermissiblyignorantoftheirharmfulness.(Theagentinthiscasemaybethecommunity

orstate).

Thepracticalrelevanceofprinciplesofcompensatoryjusticeislimited.Insofarastheharmsand

benefitsofclimatechangeareundeserved,distributivejusticewillrequirethemtobeevenedout,independentlyofcompensatoryjustice.Dutiesofdistributivejusticedonotpresupposeany

wrongdoing(seeSection3.3.4 ).Forexample,ithasbeensuggestedongroundsofdistributive

justicethatthedutytopayforadaptationshouldbeallocatedonthebasisofpeoplesabilitytopay,whichpartlyreflectsthebenefittheyhavereceivedfrompastemissions(Jamieson,1997;Shue,

1999;Caney,2010;Gardiner,2011).However,presentpeopleandgovernmentscanbesaidtoknow

aboutboththeseriouslyharmfulconsequencesoftheiremissiongeneratingactivitiesforfuture

peopleandeffectivemeasurestopreventthoseconsequences.Ifsoandiftheycanimplementthesemeasuresatareasonablecosttothemselvestoprotectfuturepeoplesbasicrights(see,e.g.,

Birnbacher,2009;Gardiner,2011),theymightbeviewedasowingintergenerationaldutiesofjustice

tofuturepeople(seeSection3.3.2 ).

3.3.6 LegalconceptsofhistoricalresponsibilityLegalsystemshavestruggledtodefinetheboundariesofresponsibilityforharmfulactionsandare

onlynowbeginningtodosoforclimatechange.Itremainsunclearwhethernationalcourtswill

acceptlawsuitsagainstGHGemitters,andlegalscholarsvigorouslydebatewhetherliabilityexists

undercurrentlaw(Mank,2007;BurnsandOsofsky,2009;FaureandPeeters,2011;Haritz,2011;Kosolapova,2011;Kysar,2011;GerrardandWannier,2012).Thissectionisconcernedwithmoralresponsibility,whichisnotthesameaslegalresponsibility.Butmoralthinkingcandrawuseful

lessonsfromlegalideas.

Harmfulconductisgenerallyabasisforliabilityonlyifitbreachessomelegalnorm(Tunc,1983),

suchasnegligence,orifitinterferesunreasonablywiththerightsofeitherthepublicorpropertyowners(Mank,2007;Grossman,2009;Kysar,2011;Bruneetal.,2012;GoldbergandLord,2012;

Kochetal.,2012).Liabilityfornuisancedoesnotexistiftheagentdidnotknow,orhavereasonto

know,theeffectsofitsconduct(AntoliniandRechtschaffen,2008).Thelawinconnectionwith

liabilityforenvironmentaldamagestillhastobesettled.TheEuropeanUnion,butnottheUnited

States,recognizesexemptionfromliabilityforlackofscientificknowledge(UnitedStatesCongress,

1980;EuropeanUnion,2004).UnderEuropeanlaw,andinsomeUSstates,defendantsarenot

responsibleifaproductdefecthadnotyetbeendiscovered(EuropeanCommission,1985;Dana,

2009).SomelegalscholarssuggestthatassigningblameforGHGemissionsdatesbackto1990when

theharmfulnessofsuchemissionswasestablishedinternationally,butothersargueinfavourofan

earlierdate(FaureandNollkaemper,2007;HunterandSalzman,2007;Haritz,2011).Legalsystemsalsorequireacausallinkbetweenadefendantsconductandsomeidentifiedharmtotheplaintiff,

inthiscasefromclimatechange(Tunc,1983;FaureandNollkaemper,2007;Kosolapova,2011;Kysar,2011;Bruneetal.,2012;EwingandKysar,2012;GoldbergandLord,2012).Acausallink

mightbeeasiertoestablishbetweenemissionsandadaptationcosts(Farber,2007).Legalsystems

generallyalsorequirecausalforeseeabilityordirectness(Mank,2007;Kosolapova,2011;vanDijk,2011;EwingandKysar,2012),althoughsomestatutesrelaxthisrequirementinspecificcases(such

astheUSComprehensiveEnvironmentalResponse,Compensation,andLiabilityAct(CERCLA),

commonlyknownasSuperfund.EmittersmightarguethattheircontributiontoGHGlevelswastoo

smallandtheharmfuleffectstooindirectanddiffusetosatisfythelegalrequirements(Sinnot

Armstrong,2010;FaureandPeeters,2011;Hiller,2011;Kysar,2011;vanDijk,2011;GerrardandWannier,2012).


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Climatechangeclaimscouldalsobeclassifiedasunjustenrichment(Kull,1995;Birks,2005),but

legalsystemsdonotremedyallformsofenrichmentthatmightberegardedasethicallyunjust

(Zimmermann,1995;AmericanLawInstitute,2011;Laycock,2012).Undersomelegalsystems,

liabilitydependsonwhetherbenefitswereconferredwithoutlegalobligationorthrougha

transactionwithnoclearchangeofownership(Zimmermann,1995;AmericanLawInstitute,2011;

Laycock,2012).Itisnotclearthattheseprinciplesapplytoclimatechange.

Asindicated,legalsystemsdonotrecognizeliabilityjustbecauseapositiveornegativeexternalityexists.Theirresponsedependsonthebehaviourthatcausedtheexternalityandthenatureofthe

causallinkbetweentheagentsbehaviourandtheresultinggainorlosstoanother.

3.3.7 Geoengineering,ethics,andjusticeGeoengineering(alsoknownasclimateengineering[CE]),islargescaletechnicalinterventioninthe

climatesystemthataimstocancelsomeoftheeffectsofGHGemissions(formoredetailsseeWGI

6.5andWGIII6.9).Geoengineeringrepresentsathirdkindofresponsetoclimatechange,besidesmitigationandadaptation.Variousoptionsforgeoengineeringhavebeenproposed,includingdifferenttypesofsolarradiationmanagement(SRM)andcarbondioxideremoval(CDR).Thissection

reviewsthemajormoralargumentsforandagainstgeoengineeringtechnologies(forsurveyssee

Robock,2008;CornerandPidgeon,2010;Gardiner,2010;Ott,2010;BetzandCacean,2012;

Preston,2013).Thesemoralargumentsdonotapplyequallytoallproposedgeoengineeringmethodsandhavetobeassessedonacasespecificbasis.7

Threelinesofargumentsupporttheviewthatgeoengineeringtechnologiesmightbedesirableto

deployatsomepointinthefuture.First,thathumanitycouldendupinasituationwheredeploying

geoengineering,particularlySRM,appearsasalesserevilthanunmitigatedclimatechange(Crutzen,

2006;Gardiner,2010;Keithetal.,2010;Svoboda,2012a;Betz,2012).Second,thatgeoengineeringcouldbeamorecosteffectiveresponsetoclimatechangethanmitigationoradaptation(Barrett,

2008).Suchefficiencyargumentshavebeencriticizedintheethicalliteratureforneglectingissues

suchassideeffects,uncertainties,orfairness(Gardiner,2010,2011;Buck,2012).Third,thatsome

aggressiveclimatestabilizationtargetscannotbeachievedthroughmitigationmeasuresaloneandthusmustbecomplementedbyeitherCDRorSRM(Greeneetal.,2010;Sandler,2012).

Geoengineeringtechnologiesfaceseveraldistinctsetsofobjections.Someauthorshavestressedthesubstantialuncertaintiesoflargescaledeployment(foroverviewsofgeoengineeringrisksseealso

Schneider(2008)andSardemannandGrunwald(2010)),whileothershavearguedthatsomeintendedandunintendedeffectsofbothCDRandSRMcouldbeirreversible(Jamieson,1996)andthatsomecurrentuncertaintiesareunresolvable(Bunzl,2009).Furthermore,ithasbeenpointed

outthatgeoengineeringcouldmakethesituationworseratherthanbetter(HegerlandSolomon,

2009;Fleming,2010;Hamilton,2013)andthatseveraltechnologieslackaviableexitoption:SRMin

particularwouldhavetobemaintainedaslongasGHGconcentrationsremainelevated(TheRoyal

Society,2009).

Argumentsagainstgeoengineeringonthebasisoffairnessandjusticedealwiththeintra

generationalandintergenerationaldistributionaleffects.SRMschemescouldaggravatesome

inequalitiesif,asexpected,theymodifyregionalprecipitationandtemperaturepatternswith

unequalsocialimpacts(Bunzl,2008;TheRoyalSociety,2009;Svobodaetal.,2011;Preston,2012).Furthermore,someCDRmethodswouldrequirelargescalelandtransformations,potentially

7Whiletheliteraturetypicallyassociatessomeargumentswithparticulartypesofmethods(e.g.,the

terminationproblemwithSRM),itisnotclearthattherearetwogroupsofmoralarguments:thoseapplicable

toallSRMmethodsontheonesideandthoseapplicabletoallCDRmethodsontheotherside.Inotherwords,

themoralassessmenthingesonaspectsofgeoengineeringthatarenotconnectedtothedistinctionbetween

SRMandCDR.


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competingwithagriculturallanduse,withuncertaindistributiveconsequences.Otherarguments

againstgeoengineeringdealwithissuesincludingthegeopoliticsofSRM,suchasinternational

conflictsthatmayarisefromtheabilitytocontroltheglobalthermostat(e.g.,Schelling,1996;

Hulme,2009),ethics(HaleandGrundy,2009;Preston,2011;HaleandDilling,2011;Svoboda,2012b;

Hale,2012b),andacriticalassessmentoftechnologyandmoderncivilizationingeneral(Fleming,

2010;Scott,2012).

Oneofthemostprominentargumentsagainstgeoengineeringsuggeststhatgeoengineeringresearchactivitiesmighthampermitigationefforts(e.g.,Jamieson,1996;Keith,2000;Gardiner,

2010),whichpresumesthatgeoengineeringshouldnotbeconsideredanacceptablesubstitutefor

mitigation.Thecentralideaisthatresearchincreasestheprospectofgeoengineeringbeingregardedasaseriousalternativetoemissionreduction(foradiscussionofdifferentversionsofthis

argumentseeHale,2012a;Hourdequin,2012).Otherauthorshaveargued,basedonhistorical

evidenceandanalogiestoothertechnologies,thatgeoengineeringresearchmightmakedeployment

inevitable(Jamieson,1996;Bunzl,2009),orthatlargescalefieldtestscouldamounttofullfledgeddeployment(Robocketal.,2010).Ithasalsobeenarguedthatgeoengineeringwouldconstitutean

unjustimpositionofrisksonfuturegenerations,becausetheunderlyingproblemwouldnotbe

solvedbutonlycounteractedwithriskytechnologies(Gardiner,2010;Ott,2012;Smith,2012).The

latterargumentisparticularlyrelevanttoSRMtechnologiesthatwouldnotaffectgreenhousegas

concentrations,butitwouldalsoapplytosomeCDRmethods,astheremaybeissuesoflongtermsafetyandcapacityofstorage.

Argumentsinfavourofresearchongeoengineeringpointoutthatresearchdoesnotnecessarily

prepareforfuturedeployment,butcan,onthecontrary,uncovermajorflawsinproposedschemes,

avoidprematureCEdeployment,andeventuallyfostermitigationefforts(e.g.,Keithetal.,2010).AnotherjustificationforResearchandDevelopment(R&D)isthatitisrequiredtohelpdecision

makerstakeinformeddecisions(LeisnerandMllerKlieser,2010).

3.4 Valuesandwellbeing

Onebranchofethicsisthetheoryofvalue.Manydifferentsortsofvaluecanarise,andclimate

changeimpingesonmanyofthem.Valueaffectsnatureandmanyaspectsofhumanlife.Thissectionsurveyssomeofthevaluesatstakeinclimatechange,andexamineshowfarthesevalues

canbemeasured,combined,orweighedagainsteachother.Eachvalueissubjecttodebateand

disagreement.Forexample,itisdebatablewhethernaturehasvalueinitsownright,apartfromthe

benefititbringstohumanbeings.Decisionmakingaboutclimatechangeisthereforelikelytobe

contentious.

Sincevaluesconstituteonlyonepartofethics,ifanactionwillincreasevalueoverallitbynomeans

followsthatitshouldbedone.Manyactionsbenefitsomepeopleatthecostofharmingothers.This

raisesaquestionofjusticeevenifthebenefitsintotalexceedthecosts.Whereasacosttoaperson

canbecompensatedforbyabenefittothatsameperson,acosttoapersoncannotbe

compensatedforbyabenefittosomeoneelse.Tosupposeitcanisnottotakeseriouslythe

distinctionbetweenpersons,asJohnRawlsputsit(1971,p.27).Harmingapersonmayinfringe

theirrights,oritmaybeunfairtothem.Forexample,whenanationseconomicactivitiesemitGHG,theymaybenefitthenationitself,butmayharmpeopleinothernations.Evenifthebenefitsare

greaterinvaluethantheharms,theseactivitiesmayinfringeothernationsrights.Othernationsmaythereforebeentitledtoobjecttothemongroundsofjustice.

Anydecisionaboutclimatechangeislikelytopromotesomevaluesanddamageothers.Thesemay

bevaluesofverydifferentsorts.Indecisionmaking,differentvaluesmustthereforebeputtogether

orbalancedagainsteachother.Somepairsofvaluesdiffersoradicallyfromeachotherthatthey

cannotbedeterminatelyweighedtogether.Forexample,itmaybeimpossibletoweighthevalueofpreservingatraditionalcultureagainstthematerialincomeofthepeoplewhosecultureitis,orto


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weighthevalueofbiodiversityagainsthumanwellbeing.Someeconomistsclaimthatonepersons

wellbeingcannotbeweighedagainstanothers(Robbins,1937;Arrow,1963).Whenvaluescannot

bedeterminatelyweighed,theyaresaidtobeincommensurableorincomparable(Chang,1997).

MultiCriteriaAnalysis(MCA)(discussedinSection3.7.2.1 )isatechniquethatisdesignedtotake

accountofseveralincommensurablevalues(DeMontisetal.,2005;ZelenyandCochrane,1982).

3.4.1 NonhumanvaluesNatureprovidesgreatbenefitstohumanbeingsinwaysthatrangefromabsorbingourwaste,tobeautifyingtheworldweinhabit.Anincreasingnumberofphilosophershavearguedinrecentyearsthatnaturealsohasvalueinitsownright,independentlyofitsbenefitstohumanbeings(Leopold,

1949;Palmer,2011).Theyhavearguedthatweshouldrecognizeanimalvalues,thevalueoflifeitself,andeventhevalueofnaturalsystemsandnatureitself.

Inmoraltheory,rationaladulthumans,whoareselfconscioussubjectsofalife,areoftentaken

(followingKant,1956)tohaveakindofunconditionalmoralworthsometimescalleddignitythatisnotfoundelsewhereonearth.Othersbelievethatmoralworthcanbefoundelsewhere(Dryzek,1997).Manyhumanbeingsthemselveslackrationalityorsubjectivity,yetstillhavemoral

worththeveryyoung,theveryoldandpeoplewithvariouskindsofimpairmentamongthem.

Giventhat,whydenymoralworthtothoseanimalsthataretosomeextentsubjectsofalife,who

showemotionalsophistication(Regan,2004),andwhoexperiencepleasure,pain,suffering,andjoy(Singer,1993)?

AnargumentforrecognizingvalueinplantsaswellasanimalswasproposedbyRichardRoutley

(1973).Routleygivesthenamehumanchauvinismtotheviewthathumansarethesolepossessors

ofintrinsicvalue.Heasksustoimaginethatthelastmanonearthsetsouttodestroyeveryliving

thing,animalorplant.Mostpeoplebelievethiswouldbewrong,buthumanchauvinistsareunabletoexplainwhy.Humanchauvinismappearstobesimplyaprejudiceinfavourofthehumanspecies

(RoutleyandRoutley,1980).Incontrast,somephilosophersarguethatvalueexistsinthelivesofall

organisms,totheextentthattheyhavethecapacitytoflourish(Taylor,1986;Agar,2001).

Goingfurther,otherphilosophershavearguedthatbiologicalcommunitiesandholisticecological

entitiesalsohavevalueintheirownright.Somehavearguedthataspecieshasmorevaluethanall

ofitsindividualshavetogether,andthatanecosystemhasstillmorevalue(Rolston,1988,1999;comparediscussioninBrennanandLo,2010).Ithasfurtherbeenproposedthat,justasdomination

ofonehumangroupbyanotherisamoralevil,showingdisrespectforthevalueofothers,thensoisthedominationofnaturebyhumansingeneral.Ifnatureanditssystemshavemoralworth,thenthedominationofnatureisalsoakindofdisrespect(Jamieson,2010).

Ifanimals,plants,species,andecosystemsdohavevalueintheirownright,thenthemoralimpactof

climatechangecannotbegaugedbyitseffectsonhumanbeingsalone.Ifclimatechangeleadsto

thelossofenvironmentaldiversity,theextinctionofplantandanimalspecies,andthesufferingofanimalpopulations,thenitwillcausegreatharmsbeyondthoseitdoestohumanbeings.Itseffectsonspeciesnumbers,biodiversity,andecosystemsmaypersistforaverylongtime,perhapseven

longerthanthelifetimeofthehumanspecies(Nolt,2011).

Itisverydifficulttomeasurenonhumanvaluesinawaythatmakesthemcommensuratewithhumanvalues.Economistsaddressthisissuebydividingvalueintousevalue(associatedwithactual

useofnatureinstrumentalvalue)andnonuseorexistencevalue(intrinsicvalueofnature).Asanexample,biodiversitymighthavevaluebecauseofthemedicaldrugsthatmightbediscovered

amongthediversebiota(usevalue).Orbiodiversitymightbevaluedbyindividualssimplybecause

theybelievethatbiologicdiversityisimportant,overandaboveanyusetopeoplethatmightoccur.

Thetotalamountpeoplearewillingtopayhassometimesbeenusedasaneconomicmeasureofthe

totalvalue(instrumentalandintrinsic)ofthesefeatures(Aldred,1994).Asthediscussionofthepast


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fewparagraphshassuggested,naturemayhaveadditionalvalue,overandabovethevaluesplaced

byindividualhumans(Broome,2009;Spashetal.,2009).

3.4.2 CulturalandsocialvaluesThevalueofhumanwellbeingisconsideredinSection3.4.3 ,butthehumanworldmayalso

possessothervaluesthatdonotformpartofthewellbeingofindividualhumans.Livingina

flourishingcultureandsocietycontributestoapersonswellbeing(Kymlicka,1995;Appiah,2010),butsomeauthorsclaimthatculturesandsocietiesalsopossessvaluesintheirownright,overand

abovethecontributiontheymaketowellbeing(Taylor,1995).Climatechangethreatensdamagetoculturalartefactsandtoculturesthemselves(Adgeretal.,2012).Evidencesuggeststhatitmay

alreadybedamagingthecultureofArcticindigenouspeoples(Fordetal.,2006,2008;Crate,2008;Hassol,2004;seealsoWGIIChapter12).Culturalvaluesandindigenouspeoplesarediscussedin

Section3.10.2 .

Thedegreeofequalityinasocietymayalsobetreatedasavaluethatbelongstoasocietyasawhole,ratherthantoanyoftheindividualswhomakeupthesociety.Variousmeasuresofthisvalueareavailable,includingtheGinicoefficientandtheAtkinsonmeasure(Gini,1912;Atkinson,1970);

foranassessmentsee(Sen,1973).Section3.5 explainsthatthevalueofequalitycanalternatively

betreatedasafeatureoftheaggregationofindividualpeopleswellbeings,ratherthanassocial

valueseparatefromwellbeing.

3.4.3 WellbeingMostpolicyconcernedwithclimatechangeaimsultimatelyatmakingtheworldbetterforpeopleto

livein.Thatistosay,itaimstopromotepeopleswellbeing.Apersonswellbeing,asthetermis

usedhere,includeseverythingthatisgoodorbadforthepersoneverythingthatcontributestomakingtheirlifegowellorbadly.Whatthingsarethosewhatconstitutesapersonswellbeing?

Thisquestionhasbeenthesubjectofanextensiveliteraturesinceancienttimes.8Oneviewisthata

personswellbeingisthesatisfactionoftheirpreferences.Anotheristhatitconsistsingoodfeelings

suchaspleasure.Athirdisthatwellbeingconsistsinpossessingtheordinarygoodthingsoflife,suchashealth,wealth,alonglife,andparticipatingwellinagoodcommunity.Thecapabilitiesapproach

ineconomics(Sen,1999)embodiesthislastview.Ittreatsthegoodthingsoflifeasfunctionings

andcapabilitiesthingsthatapersondoesandthingsthattheyhavearealopportunityofdoing,suchaslivingtooldage,havingagoodjob,andhavingfreedomofchoice.

Apersonswellbeingwillbeaffectedbymanyoftheothervaluesthatarementionedabove,andby

manyoftheconsiderationsofjusticementionedinSection3.3 .Itisbadforapersontohavetheirrightsinfringedortobetreatedunfairly,anditisgoodforapersontolivewithinahealthyculture

andsociety,surroundedbyflourishingnature.

Variousconcretemeasuresofwellbeingareinuse(Fleurbaey,2009;Stiglitzetal.,2009).Eachreflectsaparticularviewaboutwhatwellbeingconsistsin.Forexample,manymeasuresof

subjectivewellbeing(OswaldandWu,2010;KahnemanandDeaton,2010)assumethatwellbeing

consistsingoodfeelings.Monetarymeasuresofwellbeing,whichareconsideredinSection3.6 ,

assumethatwellbeingconsistsinthesatisfactionofpreferences.Othermeasuresassumewellbeing

consistsinpossessinganumberofspecificgoodthings.TheHumanDevelopmentIndex(HDI)is

intendedtobeanapproximatemeasureofwellbeingunderstoodascapabilitiesandfunctionings

(UNDP,2010).Itisbasedonthreecomponents:lifeexpectancy,education,andincome.Thecapabilitiesapproachhasinspiredothermeasuresofwellbeingtoo(DervisandKlugman,2011).In

thecontextofclimatechange,manydifferentmetricsofvalueareintendedtomeasureparticular

8Forexample:Aristotle,NicomacheanEthics.Recentworkincludes:Griffin(1986);Sumner(1999);Kraut

(2007).


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componentsofwellbeing:amongthemarethenumbersofpeopleatriskfromhunger,infectious

diseases,coastalflooding,orwaterscarcity.Thesemetricsmaybecombinedtocreateamore

generalmeasure.Schneideretal.(2000)advocatestheuseofasuiteoffivemetrics:(1)monetary

loss,(2)lossoflife,(3)qualityoflife(takingaccountofforcedmigration,conflictoverresources,

culturaldiversity,andlossofculturalheritagesites),(4)speciesorbiodiversityloss,and(5)

distributionandequity.

3.4.4 AggregationofwellbeingWhateverwellbeingconsistsof,policymakingmusttakeintoaccountthewellbeingofeveryoneinthesociety.Sothewellbeingsofdifferentpeoplehavesomehowtobeaggregatedtogether.Howdo

theycombinetomakeupanaggregatevalueofwellbeingforasocietyasawhole?Socialchoicetheorytakesupthisproblem(Arrow,1963;Sen,1970).Section3.6 willexplainthattheaimof

economicvaluationistomeasureaggregatewellbeing.

Assumethateachpersonhasalevelofwellbeingateachtimetheyarealive,andcallthistheirtemporalwellbeingatthattime.Inasociety,temporalwellbeingisdistributedacrosstimesandacrossthepeople.Whenachoiceistobemade,eachoftheoptionsleadstoaparticulardistribution

ofwellbeing.Ouraimistoassessthevalueofsuchdistributions.Doingsoinvolvesaggregating

wellbeingsacrosstimesandacrosspeople,toarriveatanoverall,socialvalueforthedistribution.

3.4.5 LifetimewellbeingNextletusassumethateachpersonstemporalwellbeingscanbeaggregatedtodeterminea

lifetimewellbeingfortheperson,andthatthesocialvalueofthedistributionofwellbeingdepends

onlyontheselifetimewellbeings.Thisistheassumptionthateachpersonswellbeingisseparable,

touseatechnicalterm.Itallowsustosplitaggregationintotwosteps.First,weaggregateeachpersonstemporalwellbeingsacrossthetimesintheirlifeinordertodeterminetheirlifetime

wellbeing.Thesecondstepinthenextsectionistoaggregateacrossindividualsusingasocial

welfarefunction.

Ononeaccount,apersonslifetimewellbeingissimplythetotaloftheirtemporalwellbeingsateach

timetheyarealive.Ifapersonswellbeingdependedonlyonthestateoftheirhealth,thisformula

wouldbeequivalenttoqalysordalys(qualityadjustedlifeyearsordisabilityadjustedlifeyears),

whicharecommonlyusedintheanalysisofpublichealth(Murray,1994;Sassi,2006).Thesemeasurestakeapersonslifetimewellbeingtobethetotalnumberofyearstheylive,adjustedfor

theirhealthineachyear.Sincewellbeingactuallydependsonotherthingsaswellashealth,qalysor

dalysprovideatbestanapproximatemeasureoflifetimewellbeing.Iftheyareaggregatedacrosspeoplebysimpleaddition,itassumesimplicitlythatayearofhealthylifeisequallyasvaluableto

onepersonasitistoanother.Thatmaybeanacceptableapproximationforthebroadevaluationof

climatechangeimpactsandpolicies,especiallyforevaluatingtheireffectsonhealth(Nordetal.,

1999;Mathersetal.,2009;butalsoseeCurrieetal.,2008).

Otheraccountsgiveeitherincreasing,(Velleman,1991)oralternativelydecreasing,(Kaplowetal.,

2010)weighttowellbeingthatcomesinlateryearsoflife,indeterminingapersonslifetime

wellbeing.

3.4.6 SocialwelfarefunctionsOncewehavealifetimewellbeingforeachperson,thenextstepistoaggregatetheselifetime

wellbeingsacrosspeople,todetermineanoverallvalueforsociety.Thisinvolvescomparingone

personswellbeingwithanothers.Manyeconomistshaveclaimedthatinterpersonalcomparisonsof

wellbeingareimpossible.9Iftheyareright,thewellbeingsofdifferentpeopleareincommensurable

9Examplesare:Robbins(1937),Archibald(1959),Arrow(1963).Asurveyanddiscussionofthisscepticalview

appearsinHammond(1993).


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andcannotbeaggregated.Inthissectionwesetthisviewaside,andassumethattemporal

wellbeingsaremeasuredinawaythatiscomparableacrosspeople.10Thisallowsustoaggregate

differentpeopleslifetimewellbeingsthroughasocialwelfarefunction(SWF)toarriveatanoverall

valueorsocialwelfare.11

WeshallfirstconsiderSWFsunderthesimplifyingbutunrealisticassumptionthatthedecisionsthat

aretobemadedonotaffecthowmanypeopleexistorwhichpeopleexist:alltheoptionscontain

thesamepeople.AtheoremofHarsanyis(1955)givessomegroundsforthinkingthat,giventhisassumption,theSWFisadditivelyseparablebetweenpeople.Thismeansithastheform:

Equation3.4.1. V=v1(w1)+v2(w2)++vJ(wJ).

Herewiispersonislifetimewellbeing.Thisformulasaysthateachpersonswellbeingcanbe

assignedavaluevi(wi),andallthesevaluesoneforeachpersonareaddeduptodeterminethesocialvalueofthedistribution.

TheproofofHarsanyisTheoremdependsonassumptionsthatcanbechallenged(Diamond,1967;

Broome,2004;Fleurbaey,2010).So,althoughtheadditivelyseparableformshowninEquation3.4.1

iscommonlyassumedineconomicvaluations,itisnotentirelysecure.Inparticular,thisformmakes

itimpossibletogiveanyvaluetoequalityexceptindirectlythroughprioritarianism,whichwas

introducedinSection3.3.2 andisdefinedbelow.ThevalueofinequalitycannotbemeasuredbytheGinicoefficient,forexample,sincethismeasureisnotadditivelyseparable(Sen,1973).

Itisoftenassumedthatthefunctionsvi()allhavethesameform,whichmeansthateachpersons

wellbeingisvaluedinthesameway:

Equation3.4.2. V=v(w1)+v(w2)++v(wJ)

Alternatively,thewellbeingofpeoplewholivelaterissometimesdiscountedrelativetothe

wellbeingofpeoplewholiveearlier;thisimpliesthatthefunctionalformofvi()variesaccordingtothedatewhenpeoplelive.Discountingoflaterwellbeingisoftencalledpurediscounting.Itis

discussedinSection3.6.2 .

EvenifweacceptEquation3.4.2,differentethicaltheoriesimplydifferentSWFs.Utilitarianism

valuesonlythetotalofpeopleswellbeing.TheSWFmaybewritten:

Equation3.4.3. V=w1+w2++wJ

Utilitarianismgivesnovaluetoequalityinthedistributionofwellbeing:agiventotalofwellbeing

hasthesamevaluehoweverunequallyitisdistributedamongpeople.

ButtheideaofdistributivejusticementionedinSection3.3.3 suggeststhatequalityofwellbeing

doeshavevalue.Equation3.4.2willgivevaluetoequalityifthefunctionv()isstrictlyconcave.Thismeansthegraphofv()curvesdownwards,asFigure3.1illustrates.(Section3.6.1.1 explainsthata

personswellbeingwiiscommonlyassumedtobeastrictlyconcavefunctionofherconsumption,

butthisisadifferentpoint.)Theresultingethicaltheoryiscalledprioritarianism.AsFigure3.1

shows,accordingtoprioritarianism,improvingapersonswellbeingcontributesmoretosocial

welfareifthepersonisbadlyoffthaniftheyarewelloff.Theprioritariansloganisprioritytothe

worseoff.Prioritarianismindirectlygivesvaluetoequality:itimpliesthatagiventotalofwellbeing

ismorevaluablethemoreequallyitisdistributed(Sen,1973;Weirich,1983;Parfit,1997).In

10Potentialbasesofinterpersonalcomparisonsareexaminedin:FleurbaeyandHammond(2004);Sen(1982);

ElsterandRoemer(1993);Mirrlees(1982);Broome,(2004);Arrow(1977);Harsanyi(1977);Adler(2011).

11ArecentmajorstudyisAdler(2011).


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judgementsaboutclimatechange,aprioritarianfunctionwillgiverelativelymoreimportancetothe

interestsofpoorerpeopleandpoorercountries.

Figure 3.1.The prioritarian view of social welfare. The figure compares the social values of increasesin wellbeing for a better-off and a worse-off person.

3.4.7 ValuingpopulationThenextprobleminaggregatingwellbeingistotakeaccountofchangesinpopulation.Climate

changecanbeexpectedtoaffecttheworldshumanpopulation.Severeclimatechangemightevenleadtoacatastrophiccollapseofthepopulation(Weitzman,2009),andeventotheextinctionof

humanbeings.Anyvaluationoftheimpactofclimatechangeandofpoliciestomitigateclimate

changeshouldthereforetakechangesinpopulationintoaccount.

TheutilitarianandprioritarianSWFsforafixedpopulationmaybeextendedinavarietyofwaystoavariablepopulation.Forexample,theutilitarianfunctionmaybeextendedtoaverageutilitarianism(Hurka,1982),whoseSWFistheaverageofpeopleswellbeing.Averageutilitarianismgivesnovalue

toincreasingnumbersofpeople.Theimplicitorexplicitgoalofagreatdealofpolicymakingisto

promotepercapitawellbeing(Hardin,1968).Thisistoadoptaverageutilitarianism.Thisgoaltends

tofavourantinatalistpolicies,aimedatlimitingpopulation.Itwouldstronglyfavourpopulation

controlasameansofmitigatingclimatechange,anditwouldnottakeacollapseofpopulationto

be,initself,abadthing.

Theutilitarianfunctionmayalternativelybeextendedtocriticallevelutilitarianism,whoseSWFis

thetotaloftheamountbywhicheachpersonswellbeingexceedssomefixedcriticallevel.Itis

Equation3.4.4. V=(w1c)+(w2c)++(wJc)

wherecisthecriticallevel(Broome,2004;Blackorbyetal.,2005).Otherthingsbeingequal,criticallevelutilitarianismfavoursaddingpeopletothepopulationiftheirwellbeingisabovethecritical

level.

Totalutilitarianism(Sidgwick,1907)iscriticallevelutilitarianismwiththecriticallevelsettozero.ItsSWFisthetotalofpeopleswellbeing.TotalutilitarianismisimplicitinmanyIntegrated

AssessmentModels(IAMs)ofclimatechange(e.g.,Nordhaus,2008).Itsmeaningisindeterminate

untilitissettledwhichleveloflifetimewellbeingtocountaszero.Manytotalutilitarianssetthe

zeroatthelevelofalifethathasnogoodorbadexperiencesthatislivedinacomathroughout,

forinstance(Arrhenius,forthcoming).Sincepeopleonaverageleadbetterlivesthanthis,total


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utilitarianismwiththiszerotendstobelessantinatalistthanaverageutilitarianism.However,it

doesnotnecessarilyfavourincreasingpopulation.Eachnewpersondamagesthewellbeingof

existingpeople,throughtheiremissionsofGHG,theirotherdemandsonEarthslimitedresources,

andtheemissionsoftheirprogeny.Ifthedamageanaveragepersondoestoothersintotalexceeds

theirownwellbeing,totalutilitarianism,likeaverageutilitarianism,favourspopulationcontrolasa

meansofmitigatingclimatechange.12

Eachoftheexistingethicaltheoriesaboutthevalueofpopulationhasintuitivelyunattractiveimplications(Parfit,1986).Averageutilitarianismissubjecttoparticularlysevereobjections.

Arrhenius(forthcoming)crystallizestheproblemsofpopulationethicsintheformofimpossibility

theorems.Sofar,noconsensushasemergedaboutthevalueofpopulation.Yetclimatechangepoliciesareexpectedtoaffectthesizeoftheworldspopulation,anddifferenttheoriesofvalue

implyverydifferentconclusionsaboutthevalueofthesepolicies.Thisisaseriousdifficultyfor

evaluatingpoliciesaimedatmitigatingclimatechange,whichhaslargelybeenignoredinthe

literature(Broome,2012).

3.5 Economics,rights,andduties

Sections3.2 ,3.3 and3.4 haveoutlinedsomeoftheethicalprinciplesthatcanguidedecision

makingforclimatechange.Theremainderofthischapterislargelyconcernedwiththeconceptsandmethodsofeconomics.Theycanbeusedtoaggregatevaluesatdifferenttimesandplaces,and

weighaggregatevaluefordifferentpolicyactions.Theycanalsobeusedtodrawinformationabout

valuefromthedataprovidedbypricesandmarkets.Economicscanmeasurediversebenefitsand

harms,takingaccountofuncertainty,toarriveatoveralljudgementsofvalue.Italsohasmuchto

contributetothechoiceanddesignofpolicymechanisms,asSection3.8 andlaterchaptersshow.

Valuationsprovidedbyeconomicscanbeusedonalargescale:IAMscanbeusedtosimulatethe

evolutionoftheworld'seconomyunderdifferentclimateregimesanddetermineaneconomically

efficientreductioninGHGemissions.Onasmallerscale,economicmethodsofCBAcanbeusedin

choosingbetweenparticularpoliciesandtechnologiesformitigation.

Economicsismuchmorethanamethodofvaluation.Forexample,itshowshowdecisionmaking

canbedecentralizedthroughmarketmechanisms.Thishasimportantapplicationsinpolicyinstrumentsformitigationwithpotentialforcosteffectivenessandefficiency(Chapters6and15).

Economicanalysiscanalsogiveguidanceonhowpolicymechanismsforinternationalcooperation

onmitigationcanbedesignedtoovercomefreeriderproblems(Chapters13and14).However,the

methodsofeconomicsarelimitedinwhattheycando.Theycanbebasedonethicalprinciples,asSection3.6 explains.Buttheycannottakeaccountofeveryethicalprinciple.Theyaresuitedto

measuringandaggregatingthewellbeingofhumans,butnottotakingaccountofjusticeandrights

(withtheexceptionofdistributivejustice seebelow),orothervaluesapartfromhumanwellbeing.

Moreover,eveninmeasuringandaggregatingwellbeing,theydependoncertainspecificethical

assumptions.Thissectiondescribesthelimitsofeconomicmethods.

Becauseoftheirlimitations,economicvaluationsareoftennotontheirownagoodbasisfor

decisionmaking.Theyfrequentlyneedtobesupplementedbyotherethicalconsiderations.Itmay

thenbeappropriatetoapplytechniquesofmulticriteriaanalysis(MCA),discussedinSection3.7.2.1

(ZelenyandCochrane,1982;KeeneyandRaiffa,1993;DeMontisetal.,2005).

12Harford(1998)showsthatanadditionalpersoncausesdamagefromherownemissionsandtheemissions

ofherchildren(andoftheirchildren,etc.).KellyandKolstad(2001)examinethisissueinthespecificcontext

ofclimatechange.


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3.5.1 LimitsofeconomicsinguidingdecisionmakingEconomicscanmeasureandaggregatehumanwellbeing,butSections3.2 ,3.3 and3.4 explainthat

wellbeingmaybeonlyoneofseveralcriteriaforchoosingamongalternativemitigationpolicies.

Otherethicalconsiderationsarenotreflectedineconomicvaluations,andthoseconsiderationsmay

beextremelyimportantforparticulardecisionsthathavetobemade.Forexample,somehavecontendedthatcountriesthathaveemittedagreatdealofGHGinthepastowerestitutionto

countriesthathavebeenharmedbytheiremissions.Ifso,thisisanimportantconsiderationindetermininghowmuchfinancerichcountriesshouldprovidetopoorercountriestohelpwiththeir

mitigationefforts.Itsuggeststhateconomicsalonecannotbeusedtodeterminewhoshouldbeartheburdenofmitigation.

Whatethicalconsiderationscaneconomicscoversatisfactorily?Sincethemethodsofeconomicsare

concernedwithvalue,theydonottakeaccountofjusticeandrightsingeneral.However,

distributivejusticecanbeaccommodatedwithineconomics,becauseitcanbeunderstoodasa

value:specificallythevalueofequality.Thetheoryoffairnesswithineconomics(Fleurbaey,2008)is

anaccountofdistributivejustice.Itassumesthatthelevelofdistributivejusticewithinasocietyisa

functionofthewellbeingsofindividuals,whichmeansitcanbereflectedintheaggregationof

wellbeing.Inparticular,itmaybemeasuredbythedegreeofinequalityinwellbeing,usingoneof

thestandardmeasuresofinequalitysuchastheGinicoefficient(Gini,1912),asdiscussedinthe

previoussection.TheAtkinsonmeasureofinequality(Atkinson,1970)isbasedonanadditivelyseparableSWF,andisthereforeparticularlyappropriateforrepresentingth

mitigation of climate change chapter3

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