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AmericanRiskPerceptions Fig.3.Americanestimatesofthenumbersofdeaths,illnesses,andinjurieseachyearbecauseofglobalwarming(impactsonhumanhealthissupportedbytheresultsoffourquestionsthataskedrespondentstoestimatethecurrentandfuturehumanhealtheffectsofglobalwarming(Fig.3).Onaverage,Americanssaidthatcurrentdeathsandinjuriesduetoglobalwarmingnumberinthehundreds,andin50yearswillnum-berinthethousands.Perhapsmoreimportant,38Ð41%ofrespondentsselectedÒdonÕtknowÓastheiranswertothesefourquestionsÑbyfarthedominantresponse.ThisisanotherstrongindicationthatAmer-icansdonotcurrentlyperceiveglobalwarmingasagravedangertohumanhealtheithernoworinthefuture.Furthermore,thisresearchalsofoundthatveryfewAmericansassociateglobalwarmingwithextremeweatherevents,likeheatwaves,hurricanes,anddroughtsÑallofwhichmayincreaseinseveritybecauseofglobalwarming.4.3.InterpretiveCommunitiesaboveaggregateresults,however,glossoversubstantialvariationinriskperceptionswithintheAmericanpublic.Inparticular,thisstudyidentiÞedseveraldistinctÒinterpretivecommunities.ÓAnin-terpretivecommunityisdeÞnedhereasagroupofindividualsthatsharecommonriskperceptions,af-fectiveimagery,culturalworldviews,andsociodemo-graphiccharacteristics.Riskperceptionsaresociallyconstructed,withdifferentinterpretivecommunitiespredisposedtoattendto,fear,andsociallyamplifysomerisks,whileignoring,discounting,orattenuat-ingothers.Forexample,thisstudyfoundoneinter-pretivecommunitythatperceivedclimatechangeasverylowornonexistentdangerÑclimatechangeÒnaysayers.ÓThisgroup,identiÞedbytheiraffec-tiveimages,wassubsequentlyfoundtobepredom- Fig.4.Riskperceptionandinterpretivecommunities.FortheÞrstnineitems,markedwitharenaysayers35,allothers450,andalarmists55.Forthelastfouritems,markedwitharenaysayers27,allothers274,andalarmists27,ÒdonÕtknowÓresponsesareexcluded.inantlywhite,male,Republican,politicallyconserva-tive,holdingpro-individualism,pro-hierarchism,andanti-egalitarianworldviews,anti-environmentalatti-tudes,distrustfulofmostinstitutions,highlyreligious,andtorelyonradioastheirmainsourceofnews(Leis-erowitz,2003).Anindependentmeans-testfoundthatnaysayersweresigniÞcantlydifferentthanallotherrespondentson13differentriskperceptionvari-ables(0.001)(seeFig.4).Furthermore,amoredetailedcontentanalysisofnaysayersÕaffectiveim-agesrevealedÞvedistinctreasonswhytheydoubtedtherealityofglobalclimatechange:1.Beliefthatglobalwarmingisnatural(ÒNor-malearthcycles,ÓÒItisjustthenaturalcourseofevents,ÓÒAnaturalphenomenonthathasbeengoingonforyearsÓ).2.Hype(ÒItisnotasbadasthemediaportrays,ÓÒTheÔproblemÕisoverblown,ÓÒEnvironmen-talisthysteriaÓ).3.Doubtingthescience(ÒThereisnoproofitex-ists,ÓÒAround10yearsorsoagoitwasglobalcooling,ÓÒJunkscienceÓ).4.Flatdenialsoftheproblem(ÒAfalsetheory,ÓÒThereisnoglobalwarmingÓ).5.Conspiracytheories(ÒHoax,ÓÒEnvironmen-talistpropaganda,ÓÒScientistsmakingupsomestatisticsfortheirjobsecurityÓ).diversityoftheseresponsesdemon-stratesthatclimatechangenaysayershaddifferent RiskAnalysis,Vol.25,No.6,2005DOI:10.1111/j.1540-6261.2005.00690.xAmericanRiskPerceptions:IsClimateChangeDangerous?AnthonyA.Leiserowitz Publicriskperceptionscanfundamentallycompelorconstrainpolitical,economic,andsocialactiontoaddressparticularrisks.Publicsupportoroppositiontoclimatepolicies(e.g.,treaties, Leiserowitzhowever,isnotyetperceivedasasigniÞcantlocalconcernamongtheAmericanpublic.FormerSpeakeroftheU.S.HouseofRepresentativesTipOÕNeillfa-mouslystatedthatÒallpoliticsislocal.ÓTotheextentthatthisistrue,climatechangeisunlikelytobecomeahigh-prioritynationalissueuntilAmericansconsiderthemselvespersonallyatrisk.4.2.AffectiveImagesofGlobalWarminghisstudyidentiÞedatotalof24distinctcat-egoriesofaffectiveimagesassociatedwithglobalwarming(Leiserowitz,2003).Thetopeightcate-gories,however,represented97%ofallrespondents(seeFig.2).Associationstomeltingglaciersandpo-laricewerethesinglelargestcategoryofresponses,indicatingthatthiscurrentandprojectedimpactofclimatechangeiscurrentlythemostsalientimageamongtheAmericanpublic(e.g.,Òmeltingpolaricecaps,ÓÒAntarcticameltingÓ).Thiswasfollowedbygenericassociationstoheatandrisingtemperatures(e.g.,ÒtemperaturesincreasingÓ),impactsonnonhu-mannature(e.g.,ÒupsetecologicalbalanceÓ),ozonedepletion(e.g.,ÒaholeintheozonelayerÓ),alarmistimagesofdisaster(e.g.,Òworlddevastation,ÓÒtheendoftheworldasweknowitÓ),sealevelriseandtheßoodingofriversandcoastalareas(e.g.,Òrisingoceanlevels,ÓÒßoodingofManhattanÓ),referencestoclimatechange(ÒachangeinclimateÓ),andÞ-nallynaysayerassociations,indicatingskepticismorynicismabouttherealityofclimatechange.MeanaffectscoresdemonstratethatthetermÒglobalwarm-ingÓevokednegativeconnotationsforalmostallre-spondents.Alarmistimagesofdisasterproducedthestrongestnegativeaffect,whilenaysayersdisplayedverylowlevelsofnegativeaffect.hus,twoofthefourmostdominantimages(meltingiceandnonhumannature),heldby34%ofallrespondents,referredtoimpactsonplacesornaturalecosystemsdistantfromtheeverydayexpe-rienceofmostAmericans.MostofthereferencestoÒheatÓwererelativelygenericinnature,andlikelyindicatedassociationswiththewordÒwarmingÓinÒglobalwarming.ÓFinally,11%ofAmericanspro-videdassociationstotheseparateenvironmentalissueofstratosphericozonedepletion,indicatingthatasub-stantialproportionofAmericanscontinuetoconfuseandconßatethesetwoissues.Thus,61%ofAmeri-cansprovidedassociationstoimpactsgeographicallyandpsychologicallydistant,genericincreasesintem-perature,ortoadifferentenvironmentalproblem. Fig.2.Americanimagesofglobalwarming.Affectwasratedona10-pointscalewhereverypositiveverynegativeheseresultshelpexplaintheparadoxinpub-licriskperceptions,inwhichAmericansappearcon-cernedaboutclimatechange,butdonotconsideritahighpriorityrelativetoothernationalorenvironmen-talissues.Thisstudyfoundthat,inaggregate,Amer-icansperceiveclimatechangeasamoderaterisk,butthinktheimpactswillmostlyaffectpeopleandplacesthataregeographicallyandtemporallydistant.Criti-cally,thisstudyfoundthatmostAmericanslackvivid,concrete,andpersonallyrelevantaffectiveimagesofclimatechange.Furthermore,oneofthemostimportantÞnd-ingswaswhatwasmissingintheseresults.Therewerenoassociationstotheimpactsofclimatechangeonhumanhealth.Therewerenoassoci-ationstotemperature-relatedmorbidityandmor-tality(e.g.,heatstroke),healtheffectsofextremeweatherevents(tornadoes,hurricanes,orprecipi-tationextremes),air-pollutionhealtheffects(e.g.,asthmaandallergies),water-andfood-bornedisease(e.g.,cholera,Escherichiacoliinfections,giardia),orvector-androdent-bornedisease(e.g.,malaria,WestNileVirus,HantavirusPulmonarySyndrome),allofwhicharepotentialhealthconsequencesofglobalcli-matechange(McMichael&Githeko,2001;NationalAssessmentSynthesisTeam,2001;Patzetal.,2000).et,humanhealthimpactsarelikelytobeamongthegreatestdangersofclimatechangeforhumansoci-eties,especiallyforthepoorandchildrenindevel-opingcountriesthatlackaccesstoadequatenutri-tion,cleanwater,ormedicalcare(IPCC,2001,p.12;atson&McMichael,2001).hisÞnding(orthelackthereof)thatAmeri-cansdonotcurrentlyassociateglobalwarmingwith AmericanRiskPerceptionsAffectiveimagesaregatheredusingthemethodofdiscreteorcontinuedwordassociations(Szalay&Deese,1978;Slovicetal.,1991;Peters&Slovic,1996).reeassociationsminimizetheresearcherbiastypi-callyimposedinclosedquestionnaires;theyareunÞl-tered,relativelycontext-free,andspontaneous,thusprovidingauniquemeanstoaccessandassesssubjec-tivemeaning.Thisnationalsurveyasked:ÒWhatistheÞrstthoughtorimagethatcomestoyourmindwhenyouthinkofglobalwarming?ÓEachself-reportedimagewasthenratedbytherespondentonaLikertaffectscalerangingfrom(verynegative)to(verypositive).Arichdatasetofmorethan700respondentassociationswasgeneratedbythistech-nique(afewrespondentsprovidedmorethanoneimage).Imagesoftentooktheformofeithersingle-wordresponses(e.g.,ÒdisasterÓ)orshortnarrativestatements.Aninductivecontentanalysiswasthenperformedwithtwoindependentcoderstoreducethedatainto24categories.3.2.3.Sociodemographicsinally,sociodemographicmeasuresincludedsex,age,income,educationalattainment,raceorethnicity,mainsourceofnews,politicalidentiÞcation,politicalideology,andvoterregistration.Worldviewsderivedfromculturaltheory(egalitarianism,fatalism,hierar-chism,andindividualism)wereoperationalizedusingsetof25questionsselectedinpartfromscalesusedbyDake(1991,1992),PetersandSlovic(1996),andRippl(2002).Detaileddescriptionsofallvariablesareavailableuponrequest.4.RESULTS4.1.AmericanRiskPerceptionsAmericansasawholeperceivedglobalclimatechangeasamoderaterisk(seeFig.1).Onaverage,Americansweresomewhatconcernedaboutglobalwarming,believedthatimpactsonworldwidestan-dardsofliving,watershortages,andratesofseriousdiseasearesomewhatlikely,andthattheimpactswillbemorepronouncedonnonhumannature.Impor-tantly,however,theywerelessconcernedaboutlocalimpacts,ratingtheseassomewhatunlikely.Themod-eratelevelofpublicconcernaboutclimatechangethusappearstobedrivenprimarilybytheperceptionofdangertogeographicallyandtemporallydistantpeople,places,andnonhumannature. Fig.1.MeanAmericanriskperceptionsofglobalwarming.Scalesrangefrom1(low)to4(high),withthemidpointindicatedbyadot-tedline.Responsecategoriesincludeseriousnessofthreattonatureandcurrentimpactsaroundtheworld(notatallveryseriouslevelofconcernaboutglobalwarming(notatallveryconcernedandthelikelihoodofspeciÞcimpactslocallyandworldwide(verylikelyhisconclusionisconÞrmedbytheresultsofaseparatequestionthataskedrespondentstoindicatewhichscaleofclimatechangeimpactswasofgreatestconcerntothem(seeTableI).Thequestionasked:ÒWhichofthefollowingareyouabout?Theimpactsofglobalwarmingon(1)youandyourfamily;(2)yourlocalcommunity;(3)theasawhole;(4)peopleallovertheworld;(5)non-humannature;or(6)notatallconcerned.Óclearmajorityofrespondents(68%)weremostconcernedabouttheimpactsonpeoplearoundtheworldandnonhumannature.Only13%weremostconcernedabouttheimpactsonthemselves,theirfamily,ortheirlocalcommunity.Thismayhelpex-plainwhyglobalclimatechangeremainsarelativelylowpriorityinissue-rankingsurveys(e.g.,Dunlap&Saad,2001).Higherrankingnationalissues(e.g.,theeconomy,education,healthcare)andenvironmen-talissues(cleanair,cleanwater,urbansprawl)areallissuesthataremoreeasilyunderstoodashav-ingdirectlocalrelevance.Globalclimatechange,bleI.MostConcernedaboutImpactson? PercentCum.Percent andyourfamily1212ourlocalcommunity113UnitedStatesasawhole922Peopleallovertheworld5072Nonhumannature1890Notatallconcerned10100otal100 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home engl.html. Leiserowitzissue.Atthesametime,however,publicopinionpollsandacademicstudiesconsistentlyshowthatAmeri-cansregardboththeenvironmentandclimatechangeasrelativelylownationalpriorities(Dunlap&Scarce,1991;Bordetal.,1998,p.77).Forexample,ina2000Galluppoll,theenvironmentranked16thonAmericansÕlistofmostimportantproblemsfacingthecountrytoday.Furthermore,globalwarmingranked12thoutof13environmentalissues,justbelowurbansprawl(Dunlap&Saad,2001).Thus,Americanspara-doxicallyseemtobehighlyconcernedaboutglobalwarmingasanindividualissue,yetviewitaslessim-portantthannearlyallothernationalorenvironmen-talissues.hileuseful,publicopinionpollshavelimitedutilityforexplainingpublicriskperceptionsofglobalclimatechange.Mostpollsuseonlyrelativelysimple,holisticmeasuresofconcern(e.g.,ÒHowseriousofathreatisglobalwarming?Ó),whichprovidelittlein-sightintothedeterminantsandcomponentsofpublicriskperception.Whydosomeseeclimatechangeasanurgent,immediatedanger,whileothersviewitasgradual,incrementalproblem,ornotaproblematall?Howsevereandhowlikelydotheythinktheim-pactswillbe?Andimportantly,whatistheiraffectiveresponsetoglobalwarming?remainderofthisarticlereportsresultsfromrecentnationalstudyofAmericanriskperceptions,policypreferences,andindividualbehaviors,whichprovidefurtherinsightintohowtheAmericanpub-liccurrentlyperceivesandinterpretsthedangersofglobalclimatechange.3.METHODS3.1.ProcedureandRespondentsnationalstudyofAmericanclimatechangeriskperceptions,policypreferences,andbehaviorswasconductedfromNovember2002toFebruary2003.studywasimplementedwitha16-pagemail-out,mail-backsurveyofarepresentativesampleoftheAmericanpublic,usingtheDillman(2000)tailoreddesignmethod.Atotalof673completedsurveyswerereturnedforanoverallCASROresponserateof55.4%andarefusalrateof11.2%.Comparedwiththepopulationdistributionsfromthe2000U.S.Census,thesampleoverrepresentedmales(65%)andpersons55andolder(47%).Theresultswereweightedbysexandagetobringtheminlinewithactualpopulationproportions.3.2.Measures3.2.1.RiskPerceptionSeveralmeasuresofpublicriskperceptionwereimplemented,includingholisticconcern;assessmentsoftheseverityofcurrentandfutureimpactsofglobalclimatechangeonhumanhealth(mortalityandmor-bidity);likelihoodmeasuresoflocalandglobalim-pactsofclimatechangeonstandardsofliving,watershortages,andratesofseriousdisease;theserious-nessofthethreattononhumannature;andthese-riousnessofthecurrentimpactsofclimatechangearoundtheworld,andscaleofconcern(seeFig.1andableI).3.2.2.AffectiveImageryRecentresearchhasdemonstratedthecrucialroleofaffectandemotioninriskperceptionandbe-havior(e.g.,Finucaneetal.,2000;Slovicetal.,2002),andtheutilityofaffectiveimageanalysisasameanstostudytherelationshipbetweenaffect,cognitiveimagery,andperceivedrisk(e.g.,Slovicetal.,1991;Leiserowitz,2003;SatterÞeld,2001).referstothespeciÞcqualityofÒgoodnessÓorÒbadnessÓexperiencedasafeelingstate(withorwithoutconsciousawareness)orthepositiveornega-tivequalityofastimulus.AffectisheredistinguishedwhichgenerallyreferstospeciÞc,tran-sitorystatessuchasangerandfear.Affectisalsodis-tinctfromwhichgenerallyreferstotransitory,low-intensityfeelingsthatareundirectedandlackspeciÞccognitivecontent.Bycontrast,referstopersonÕsrelativelystablepositiveornegativeeval-uationofspeciÞccognitivecontentsorimages.ItisalsoÒanorientingmechanismthatdirectsfundamen-talpsychologicalprocessessuchasattention,memory,andinformationprocessingÓ(Slovic,1997,p.292).referstoallformsofmentalrepresen-tationorcognitivecontent.Imagesincludebothper-ceptualrepresentations(pictures,sounds,smells)andsymbolicrepresentations(words,numbers,symbols)(Damasio,1999,pp.317Ð321).Inthissense,ÒimageÓreferstomorethanjustvisually-basedmentalrepre-sentations.AffectiveimagesarethusÒbroadlycon-struedtoincludesights,sounds,smells,ideas,andwords,towhichpositiveandnegativeaffectorfeel-ingstateshavebecomeattachedthroughlearningandexperienceÓ(Slovicetal.,1998,p.3).Affectiveimagesareevaluativefeelingsofgood/positiveorbad/negativeassociatedwithparticularconceptsor AmericanRiskPerceptionsandpsychologicalqualitiesofhazardsthatarenotwell-modeledintechnicalriskassessmentsÓ(Slovic,2000,p.392).Inlargepart,whoevercontrolsthedeÞnitionofÒdangerousÓclimatechangecontrolstherationalso-lutiontotheproblem.IfdangerisdeÞnedoneway,thenonesetofsolutionswillemergeasthemostcost-effectiveorthesafest.Asjustoneexample,somesci-entistsarguethatthepotentialcollapseoftheWestAntarcticIceSheetwouldrepresentÒdangerousÓcli-matechange,assuchaneventcouldincreasesealev-elsbyupto2metersover100Ð300years,inundatingcoastlinesandcitiesaroundtheworldandÒcausingtheforcedmigrationoftenstohundredofmillionsofpeopleÓ(Hansen,2005,p.274).Ifdangerisde-Þnedinreferencetothisand/orthepotentialdisin-tegrationoftheGreenlandIceSheet,thentheworldcanperhapsÒsafelyÓwarmanadditional1(Hansen,2005)to2Ð4F)(Oppenheimer&Alley,2005).Asealevelriseof2metersmightwellbeuniversallyviewedasÒdangerous,ÓyetthereremaingreatscientiÞcuncertaintiesabouthowtheicesheetswillrespondtoincreasedglobalwarming.Fromapol-icystandpoint,Oppenheimerposesacriticalquestion:ÒGiventheuncertainties,iscurrentunderstandingofthevulnerabilityofeithericesheetpotentiallyusefulindeÞningÔdangerousanthropogenicinterferenceÕinthecontextofArticle2?Ó(Oppenheimer&Alley,2005,p.263).IfdangerisdeÞnedanotherway,however,amuchlowerthresholdandadifferentsetofsolutions,signiÞ-cantlymorestringent,mayberequired.Forexample,climatechangeisalreadyhavingsevereimpactsontheArctic,includingtheU.S.StateofAlaska(ArcticMonitoringandAssessmentProgram,2005).AlaskaÕsclimatehaswarmedabout4F(2C)sincethe1950sand7F(4C)intheinteriorduringwinter.Thestateexperienceda30%averageincreaseinprecipitationbetween1968and1990.Seaicehasretreatedby14%since1978andthinnedby60%sincethe1960swithwidespreadeffectsonmarineecosystems,coastalclimate,andhumansettlements.Permafrostmeltinghascausederosionandlandslidesanddamagedin-frastructureincentralandsouthernAlaska.RecentwarminghasbeenaccompaniedbyÒunprecedentedincreasesinforestdisturbances,includinginsectat-tacks.Asustainedinfestationofsprucebarkbeetles,whichinthepasthavebeenlimitedbycold,hascausedwidespreadtreedeathsover2.3millionacresontheenaiPeninsulasince1992,thelargestlosstoin-sectseverrecordedinNorthAmericaÓ(NationalAs-sessmentSynthesisTeam,2001).RobertCorell,leadscientistoftherecentinternationalArcticClimateImpactAssessment,recentlystated:ÒIfyouwanttoseewhatwillbehappeningintherestoftheworld25yearsfromnow,justlookatwhatÕshappeningintheArcticÓ(Borenstein,2003).Thus,somemightarguethatthedramaticimpactsofclimatechangeonArc-ticecosystems,cultures,foodproductionsystems,andeconomiesalreadyqualiÞesasaÒdangerousÓlevelofclimatechange,requiringgreaterandfasterreduc-tionsinglobalgreenhousegasemissions.DeÞningdangerousclimatechangeininterna-tionalnegotiationsmayultimatelybeanexerciseinpower.ThosewiththepowertodeÞnethetermsofthedebatestronglydeterminetheoutcomes(Slovic,2000,p.411).ItisthuscriticalthatthenegotiationofÒdangerousÓlevelsofclimatechangebeopenedtomultiplevoicesandmultipleperspectives,includingthebroaderglobalpublic,asthedangersdependlit-erallyandÞgurativelyonwhereonestands,whilethesolutionswillrequirethecoordinatedactionofusall.CKNOWLEDGMENTShisresearchwassupportedbyagrantfromtheNationalScienceFoundation(SES-0221896)andsev-eralgrantsfromtheDonaldR.BarkerFoundation.authorthanksPaulSlovic,NickPidgeon,IreneLorenzoni,SusiMoser,JenniferMarlon,andthreeanonymousreviewersfortheircommentsonearlierdrafts.REFERENCESArcticMonitoringandAssessmentProgram.(2005).ImpactsofaarmingClimateÑArcticClimateImpactAssessmentbridge:CambridgeUniversityPress.Bord,R.J.,Fisher,A.,&OÕConnor,R.E.(1998).Publicpercep-tionsofglobalwarming:UnitedStatesandinternationalper-spectives.ClimateResearchBorenstein,S.(10August2003).Alaskaislessfrozenthanitoncewas,andtheeffectsaredevastating.MilwaukeeJournalSen-,p.21.Bostrom,A.,Morgan,M.G.,Fischhoff,B.,&Read,D.(1994).Whatdopeopleknowaboutglobalclimatechange?RiskAnalysis(6),959Ð970.Brewer,T.L.(2002).USPublicOpiniononClimateChangeIs-vailableathttp://www.ceps.be/Þles/ClimateDialogue/USpublicopinion.pdf.Christianson,G.E.(1999).Greenhouse:The200-YearStoryofGlobalWarmingNewYork:WalkerandCompany.Dake,K.(1991).Orientingdispositionsintheperceptionofrisk:Ananalysisofcontemporaryworldviewsandculturalbiases.ournalofCross-CulturalPsychologyDake,K.(1992).Mythsofnature:Cultureandthesocialconstruc-tionofrisk.ournalofSocialIssuesDamasio,A.(1999).TheFeelingofWhatHappensNewYork: AmericanRiskPerceptionsintheUnitedStatesuntilthesummerof1988Ñatthattimethehottestyearsincethemiddleofthe19thcentury.OnJune23,theseconddayofsum-mer,SenatorTimothyWirthofColoradoconvened.S.SenateEnergyandNaturalResourcesCom-mitteehearingonclimatechange.Thedateofthehearinghappenedtofallduringaheatwavesweep-ingovermuchofthenationandonadaythattem-peraturesreachedarecord101C)inaswel-teringWashington,DC.Atthehearing,Dr.JamesHansen,directoroftheNASAGoddardInstituteofSpaceStudiesandaleadingclimatemodeler,testiÞedthatÒthegreenhouseeffecthasbeendetectedanditischangingourclimatenowÓ(Christianson,1999,196).HansenÕstestimonybecamefront-pagenewsacrossthecountry.Asthesummerof1988con-tinued,severedroughtgrippedtheMidwestandSoutheast.ÒTwothousanddailytemperaturerecordsweresetthatyearintheUnitedStates.WidespreadheatanddroughtcausedsomecropyieldsintheMidwesttofallbetween30and40percentÓ(Johansen,2002,p.43).Nationwide,anestimated10,000deathswerelinkedtoheatstress.InLosAn-geles,400electricaltransformersblewuponadayinwhichtemperaturesreached110C)inSeptem-ber(Christianson,1999,p.197).Aftertheeventsof1988andsubsequentyears,numerouspublicopinionpollsfoundthatAmericanswereincreasinglyawareofandconcernedaboutglobalclimatechangeandsupportiveofawiderangeofmitigationandadapta-tionpolicies.By2001,aLosAngelesTimespollfound,inresponsetothequestionÒHaveyouheardorreadanythingabouttheissueofglobalwarm-ing?Óthat82%ofAmericansansweredÒyes,Ó14%saidÒno,Óand4%saidÒdonÕtknowÓ(PIPA,2003).hroughoutthe1990s,thefossilfuelindustry,rep-resentedbylobbygroupsliketheGlobalClimateCoalition,spearheadedapublicrelationsefforttocastdoubtonthescienceandrealityofanthropogenicclimatechange(seeGelbspan,1997;Leggett,2001).hiscampaign,whileachievingseveralshort-termvic-tories,appearstohavelostthelargerwarforpub-licopinion.In1994,attheheightofindustryef-forts,anationalpollbyCambridgeReportsfoundthatonly28%ofrespondentssaidthatÒthereisaconsensusamongthegreatmajorityofscientiststhatglobalwarmingexistsandcoulddosigniÞcantdam-age,Ówhile58%saidthatscientistsaredividedontheexistenceofglobalwarminganditsimpact.By1997,CNN/USATodaypoll,however,foundthat48%thoughtÒmostscientistsbelievethatglobalwarm-ingisoccurring,while39%thoughtÒmostscientistsareunsureaboutwhetherglobalwarmingisoccur-ringornot.ÓMostrecently,a2001Galluppollfoundthat61%ofrespondentssaidÒmostscientistsbelievethatglobalwarmingisoccurring,Ówhileonly30%saidmostscientistsareunsure(PIPA,2003).Thus,majorityofAmericansnowbelievethatthereisscientiÞcconsensusontherealityofglobalclimatechange.Furthermore,virtuallyallpollstakensince1997havefoundthatalargemajorityofAmericansbelieveglobalwarmingisreal.Mostrecently,aHarrisInteractivepollconductedinSeptember2002foundthat74%saidtheyÒbelievethetheorythatincreasedcarbondioxideandothergasesreleasedintotheat-mospherewill,ifunchecked,leadtoglobalwarm-ingandanincreaseinaveragetemperaturesÓ(PIPA,PublicopinionpollsalsodemonstratesigniÞcantlevelsofpublicworryaboutglobalwarming.InMay1989,aGallupsurveyofAmericanpublicasked:ÒHowmuchdoyoupersonallyworryaboutthegreen-houseeffectorglobalwarming?ÓGallupfoundthat35%worriedÒagreatdeal,Ó28%worriedÒafairamount,Ó18%worriedÒonlyalittle,Óand12%wor-riedÒnotatall.ÓThus,63%ofAmericanswerefairlytogreatlyworriedaboutglobalwarmingin1989.Gallupfoundthatthislevelofworryoscillatedoverthesubsequent14years,withadipto50%in1997,anincreaseto72%in2000,andadecreaseto58%in2002(Brewer,2002).Thegeneraldeclineinlevelsofworrymaypartlybetheresultofchangingme-diacoverage.Duringtheunusuallyhotsummerof1988,globalwarmingwasafront-pagestoryacrossthecountry.AmediaanalysisbytheCenterforMediaandPublicAffairsfound,however,thatsince1990,tele-visionnetworkcoverageofglobalwarmingdeclinedby50%,whilenationalnewspapercoveragedroppedby25%(FrameWorksInstitute,2001).Otherpollingorganizationshavemeasuredpub-liclevelsofconcernbyusingvariouspermutationsofthequestion:Howseriousofaproblem/threatisglobalwarming?Ina1998MellmanGroupna-tionalpoll,70%ofvoterssaidglobalwarmingwasaÒveryseriousÓorÒsomewhatseriousÓthreat.By2001,ime/CNNfoundthat76%thoughtglobalwarm-ingaÒveryseriousÓorÒsomewhatseriousÓproblem.Despitethevariabilityindicatedbydifferentpollingmethods,itisclearthatpubliclevelsofconcernaboutglobalwarminghaveremainedconsistentlyhighsinceOverall,Americanscurrentlydemonstrateahighawarenessofglobalclimatechange,astrongbeliefthatitisreal,andhighlevelsofconcernaboutthe Leiserowitzrationalesfortheirdisbelief,rangingfromacceptanceoftherealityofclimatechange(althoughnaturallycausedoroverblown)toßatdenialsandoutrightcon-spiracytheories.Thisinterpretivecommunityisthusstronglypredisposedtodiscountorßatlyrejectscien-tiÞcassessmentsanddeÞnitionsofÒdangerousÓcli-matechange.Whileonlyapproximately7%oftheadultpopulation(or12millionpeople)accord-ingtothissurvey,naysayersarepoliticallyactive,aresigniÞcantlymorelikelytovote,havestrongrepre-sentationinnationalgovernment,andhavepowerfulalliesintheprivatesector.hisstudyalsoidentiÞedacontrastinginterpre-tivecommunitywithhigh-riskperceptionsofcli-matechangeÑalarmists.Somemembersofthisgroupprovidedextremeimagesofcatastrophicclimatechange,suchas:ÒBadlikeafternu-clearwarnovegetation,ÓÒHeatwaves,itÕsgonnakilltheworld,ÓÒDeathoftheplanet.ÓAlarmistsheldpro-egalitarianandanti-individualistandhier-archistworldviews,werepoliticallyliberal,stronglysupportedgovernmentpoliciestomitigateclimatechange(includingraisingtaxes),andweresigniÞ-cantlymorelikelytohavetakenpersonalactiontoreducegreenhousegasemissions.Anindependent-testfoundthatthisinterpretivecommunitywassigniÞcantlydifferentfromallotherrespondentsoneveryriskperceptionvariable(8variables:0.01;5variables:0.001)(seeFig.2).Alarmistsrepresentapproximately11%oftheAmericanpub-lic.Itisalsoimportanttonote,however,thatallotherrespondentshadclimatechangeriskperceptionlevelsmuchclosertoalarmiststhannaysayers(Fig.4).ThisdemonstratesthatmostAmericansarepredisposedtoviewclimatechangeasasigniÞcantdanger,albeitnotasextremeasthealarmists,whileclimatechangenaysayershavesubstantiallylowerriskperceptionsthantherestofAmericansociety.inally,thisstudyidentiÞedanotherinterpre-tivecommunitywhosemembersconfuseorconßateglobalclimatechangewiththeseparateproblemofstratosphericozonedepletionÑacriticalmisconcep-tionalsoidentiÞedbymentalmodelsresearchers(e.g.,Naysayersdonotappeartohavebeeneitherover-orunderrepre-sentedinthissurvey.Comparedwiththepopulationdistributionsfromthe2000U.S.Census,thesampledidoverrepresentmales(65%)andpersons55andolder(47%).Therefore,thedatawereweightedbysexandagetobringtheminlinewithnationalpop-ulationproportions.Furthermore,theproportionsofconserva-tives(32%)andRepublicans(27%)inthesample(twocommoncharacteristicsofnaysayers)werenotsigniÞcantlydifferentthannationalproportions.etal.,1995;Bostrometal.,1994;Readetal.,1994).Demographically,membersofthiscom-munityonlytendedtobeyoung.Nonetheless,theyrepresentasigniÞcantproportionoftheAmericanpublic(11%).Ozone-hole-relatedimageshadthethirdhighestlevelofnegativeaffect,whichstronglysuggeststhattheseindividualsalreadyviewclimatechangeasdangerous,albeitforthewrongreasons(e.g.,fearofcontractingskincancer).5.DISCUSSIONOverall,mostAmericansdemonstrateahighawarenessofglobalclimatechange,astrongbeliefthatitisreal,andsigniÞcantconcernabouttheissue.Ontheotherhand,theresultsreportedheredemon-stratethatthemajorityoftheAmericanpublicdoesnotcurrentlyconsiderclimatechangeanimminentorhigh-prioritydanger.Instead,mostAmericanscur-rentlybelievethattheimpactsofclimatechangewillhavemoderateseverityandwillmostlikelyimpactge-ographicallyandtemporallydistantpeopleandplacesornonhumannature.Yet,withintheAmericanpublic,severaldistinctinterpretivecommunitieswerefound,rangingfromalarmistswithextremeriskperceptionstonaysayers,someofwhomviewclimatechangeashoaxperpetratedbyscientistsandenvironmental-ists.Clearly,eachoftheseinterpretivecommunitieswilldeÞneÒdangerousanthropogenicinterferencewiththeclimatesystemÓinradicallydifferentways.Manyalarmistsareconvincedthatanydegreeoffur-therhumaninterferencewillhavecatastrophiccon-sequences,whilemanynaysayersareconvincedthathumanactivitieshavelittletonoinßuence,orevenapositiveinßuenceontheclimatesystem.InbetweenthesetwoextremesareotherAmericanswhoeitherviewclimatechangeasmoderateriskorconfuseitwiththedangersofstratosphericozonedepletion.meaningofÒdangerousÓclimatechangewillcontinuetobecontestedbytheseinterpretivecom-munities,aswellasbyclimatechangescientists,spe-cialinterestgroups,andpoliticalelites,alloperatingatdifferentspatialscales.TheprecisemeaningofÒdan-gerousÓwillalsocertainlybecontestedinfuturein-ternationalnegotiationstoreduceglobalgreenhousegasemissionsbeyondtheinitialstepsoftheKyotoProtocol.Inthismoreorlessdemocraticprocess,ex-pertdeÞnitionsofthetermÒdangerousÓandidentiÞ-cationofdangerousthresholdsinphysicalandsocialsystemsarevitallyimportantinputsintothedecision-makingprocess.ButsoarelaypublicdeÞnitionsofÒdangerous,ÓwhicharesensitivetoÒtechnical,social Leiserowitzclimatesystem.ÓTheprospectoffurtherlegalandeconomicpenaltiesforfailuretoachievenationalemissionstargetsinvestsboththeprecisemeaningandmeasurementofÒdangerousÓclimatechange,andtheprocessbywhichitisdeÞned,withanewsigniÞcance.Inaddition,ÒdangerousÓclimatechangewillbedeÞneddifferentlybydifferentstakeholders.Forex-ample,twoimportantinßuencesonpolicymakers(amongothers)arescientistsandthelaypublic.Ex-pertdeÞnitionsofdangerderivefromscientiÞceffortstoidentify,describe,andmeasurethresholdsinphys-icalvulnerabilitytonaturalecosystems(e.g.,coralreefs)ortocriticalcomponentsofthecurrentclimatesystem(e.g.,theThermohalineCirculationSystem).ExpertdeÞnitionsofdangerousclimatechangealsoderivefromscientiÞceffortstodeÞnethresholdsinsocialvulnerabilitytoclimatechange,includingin-creasedratesofinfectiousdisease,destabilizationofinternationalorder,orsevereeconomicimpacts.Fi-nally,expertdeÞnitionsincludeeffortstoidentifypar-ticularlevelsofatmosphericgreenhousegasconcen-trationsoraverageglobaltemperatureasceilingsbe-neathwhichdangerousclimatechangecanbeavoided(e.g.,450partspermillionvolumeofcarbondiox-ideor2F)warmerthanpreindustriallevels)(OÕNeill&Oppenheimer,2002;WBGU,2003).Laypublicperceptionsandinterpretationsofdangerousclimatechange,however,areÒbasedonpsychological,social,moral,institutionalandculturalprocessesÓ(Dessaietal.,2004).WhileexpertstendtonarrowlydeÞnerisksusingtwodimensions(e.g.,prob-abilitiesandseverityofconsequences),thegeneralpublichasbeenfoundtoutilizeamuchmoremultidi-mensionalandcomplexsetofassessments.PublicriskperceptionsareinßuencednotonlybyscientiÞcandtechnicaldescriptionsofdanger,butalsobyavarietyofpsychologicalandsocialfactors,includingpersonalexperience,affectandemotion,imagery,trust,values,andworldviews(Slovic,2000).Furthermore,publicriskperceptionsarecriti-calcomponentsofthesociopoliticalcontextwithinwhichpolicymakersoperate.Publicopinioncanfun-damentallycompelorconstrainpolitical,economic,andsocialactiontoaddressparticularrisks.Forex-ample,publicsupportoroppositiontoclimatepoli-cies(e.g.,treaties,regulations,taxes,subsidies)willbegreatlyinßuencedbypublicperceptionsoftherisksanddangersinherentinclimatechange.Thus,bothexpertandlaypublicinterpretationsofdangerouscli-matechangeareimportantcomponentsofthepolicy-makingprocess.1.1.TheImportanceofPublicRiskPerceptionsintheUnitedStatesInthiscontext,Americanpublicriskperceptionsofclimatechangearecriticalforatleasttworea-sons.First,theUnitedStates,withonly5%oftheworldÕspopulation(U.S.CensusBureau,2005),iscur-rentlytheworldÕslargestemitterofcarbondioxide,theprimaryheat-trappinggas,aloneaccountingfornearly25%ofglobalemissions.Percapita,Ameri-cansemit5.40metrictonsofcarboneachyear.Bycomparison,theaverageJapaneseemits2.55tonsperyear,whiletheaverageChineseemitsonly0.60andtheaverageIndianonly0.29tonsperyear(Marlandetal.,2003).Second,successiveU.S.presidentsandcongressionalleadershavebeenatoddswithmuchoftheworldcommunityregardingthereality,se-riousness,andneedforvigorousactiononclimatechange.Forexample,in1997,justpriortotheKyotoclimatechangeconference,theU.S.Senatepassedanonbindingresolution(95Ð0)co-sponsoredbyRobertByrd(D)ofWestVirginiaandChuckHagel(R)ofNebraska,whichurgedtheClintonadministrationtorejectanyagreementthatdidnotincludeemissionlimitsfordevelopingaswellasindustrializedcoun-tries,arguingthattodosowouldputtheUnitedStatesatacompetitiveeconomicdisadvantage(Sen-ateResolution98,1997).Furthermore,in2001Pres-identGeorgeW.Bushrenouncedacampaignpledgetoregulatecarbondioxideasapollutant,withdrewtheUnitedStatesfromtheKyotoProtocolnegotia-tions,andproposednationalenergylegislationtoin-creasedrillingforoilandnaturalgas,increaseminingforcoal,andbuildmorethanathousandnewfossil-fuel-burningpowerplants(Pianin&Goldstein,2001;Revkin,2001;UnitedStates,2001).Clearly,theAmer-icanpublicwillplayacriticalrole,bothintermsoftheirdirectconsumptionoffossilfuels,andresultinggreenhousegasemissions,andthroughtheirsupportforpoliticalleadersandgovernmentpolicies,intheefforttomitigateoradapttoglobalclimatechange.hisarticlesummarizescurrentpublicopiniononclimatechangeandreportsresultsfromarecentstudyofAmericanriskperceptions,policypreferences,andindividualbehaviors.2.BACKGROUND2.1.PublicOpinionPollsDespitescientiÞcwarningsinpriordecades(e.g.,Revelle&Suess,1957;1979),globalclimatechangedidnotbecomeasigniÞcantpublicconcern KEYWORDS:Affectiveimagery;climatechange;dangerous;interpretivecommunities;riskperception1.INTRODUCTIONultimateobjectiveofthe1992UnitedNationsrameworkConventiononClimateChangeÒisto