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EssayonWarmingPapers

TheWarmingPapersisacollectionofclassicscientificpapersthatlaythefoundationofmoderndayunderstandingofglobalclimatechange.Itspansnearlytwocenturiesofresearch,documentingdeepinsight,leapsofunderstandingandthe

mathematicalrigorsrequiredtoaddressconvincinglythechallengesfacedbyanascentfieldofinquiry.Editors,DavidArcherandRayPierrehumbert,takeusthroughthejourneywiththeirinsightfulcommentsandboxedexplanationsthatmakeiteasytoreadandwhenthemathgetsterse,theyusewordsandpicturestokeepusinterested.ItispublishedbyWiley-Blackwell(andcosts$58.73atAmazon)andhasreceivedsomegoodreviews,acouplearecopiedbelow."SummingUp:Highlyrecommended.Upper-divisionundergraduatesandabove;

generalaudiences."(Choice,1August2011)"AheftynewvolumepublishedbyWiley-Blackwellandeditedbytheclimatescientists

DavidArcherandRaymondPierrehumbertattheUniversityofChicago,it'sarichfeastforanyonewhowantstotracethehistoryofclimatesciencefromitsearliestoriginsto

thepresent."(TheNewYorkTimes,February2011)

Ichosetoreview5papersbygiantsinthefield.Together,thesetracethehistoryoftheunderstandingofglobalclimatechange,eachalandmarkinthedevelopmentofscienceleadingtoourcurrentunderstanding.

TheGreenhouseEffectJ.Fourier

Fourier,J(1827).Memoiresurlestemperaturesduglobeterrestreetdes

espacesplanetaires.MemoiresdelAcademieRoyaledesSciences,7,569604.

(25pages)

FourierIntroducedtheconceptofstudyingplanetarytemperatureasaobjectofstudyinphysics.Healso,insomeways,introducedtheconceptofGlobalwarming.Itcouldbearguedthathepresentedmostlyaqualitativeargument,butthatsmostlybecausetheframe-workheneededtodescribethemathwas

notyetavailable.Infact,hepioneeredthedevelopmentdifferentialequationsthatbearshisnametoruleouttheeffectofplanetscoretemperatureasafactorinsurfacetemperatureofearth.AroundthetimeFourierdevelopedhistheories,IR,thencalleddarkheatwasjustdiscovered(1800bySirFrederickWilliamHerschel).AndtheconceptofRateoflossofheatasIRfromabodywasjustintroducedbyDulongandPetitandthatheatcouldbecarriedinnearvacuum.Itisworthrecallingthatscience

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wasnotyetoutoftheconceptthatrequiredamediumtocarryanyforce,includingenergy-ether.ThermodynamicswasinitsinfancyandthelandmarkexperimentbyJoulewasyettobecarriedout(1843).Againstallthis,hiscontributionseemshuge.

Heintroduced5keyconcepts: TemperatureofearthisdeterminedbyabalanceofEnergyradiatingin

andout,hencetheneedtodeterminethesourceandsinkofenergyinthisbalance.

Thatthereare3possiblesourcesofheat.o Sunlighto Heatdiffusingfromhotinterior,althoughitplayedaverysmall

rolethisheshowedthroughhisinnovativemathematicsofthattimedifferentialcalculus,whereinhecalculatedtheheatdiffusionthroughlayersofearthusingvaryingboundaryconditions.

o Heatfromgeneraltemperatureofspace IRistheonlymeansbywhichearthlosesheat.Andthebalanceofenergy

betweenheatradiatinginandoutdeterminesthetemperatureofearth.

EarthbodyconvertsvisiblelighttoIR(heat) Atmospherehasasymmetriceffectonincomingandoutgoingradiation

itislargelytransparenttoincoming(visible)butopaquetooutgoing(IR).

Itturnsoutthathewaswrong(blunderisthewordEditorsuse)insayingthatthegeneraltemperatureofspacewasequivalenttothatofthepoles(~200K,actuallyiscloserto5K).Hereasonedthatthisiswhyearthdidnotcooldowndramaticallyduringthenight-timeandremainedwarmenoughforlifetosurvive.Althoughhisworksindicatethathewasawarethatthecoolingwouldtakealotlongerthanfewhoursduetothermalcapacityandthatwindsandoceancurrentscouldinfacttransferheat,forunknownreasonshefailedtoapplythesearguments.IntheoryhecouldhavecalculatedearthsmeantemperatureusingtheenergybalancetheoryheproposedandusingDulongandPitetstheoryofradiation,butdidnotdoso.Finally,itisworthmentioningthatFourierdidshowtheGreenhouseeffect,butDIDNOTcointhetermGreenhouse!

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WaggingtheDogJ.Tyndall

Tyndall,J.(1861).Ontheabsorptionandradiationofheatbygasesand

vapours,andonthephysicalconnexionofradiation,absorptionandconduction.PhilosophicalMagazineSeries4,22,169194,273285,(12pages).

Tyndallwasanamazingexperimentalist:

Hemeasuredtheabsorptionofradiationbycoolgas. HediscoveredthatgaseswhenheatedemitIR. DiscoveredwhatisnowpatentlyknownasKirkhoffslaw,i.e.,gasthat

isapoorreflectorisagoodemitter,andagoodreflectorisapooremitter

Discoveredthatindilutegases,absorptionincreasesproportionately(linearly)toconcentration,butsaturatesathighenoughconcentrationscalledbandsaturationamuchdebatedpointeventoday!

Heusedathermopileacollectionofthermocouples(thermocoupleadevicethathastwopolesandproducesavoltageproportionaltothedifferenceintemperaturebetweenthepoles)andagalvanometer(todaycalledanammeter)tomeasureincomingradiation.Tocarryouthisexperiments,heimprovedgalvanometersensitivity.Hemadechangesthatshowhisattentiontodetailsandhispassionforaccuracy.E.g.,hechangeddyeinsilkusedtoinsulatethecoilingalvanometerstatingthatthedyewasmagnetic!Hegoesontobalancetwothermopileagainsteachother,thusvastlyimprovingthesensitivityoftheradiationabsorptionhewasmeasuring.Heusedthistechniquewithgreatsuccesstomeasureabsorptionbydilutemixtureofgases.

Hijawdroppingcontributionwasthediscoverythatallgreenhouseactivityoftheatmosphereisduetoafewtracegasescouldinfactchangetheclimateglobally!HepointedtoCO2andWatervaporasmajorroleplayers.Itisindeedamazingthathearrivedatthisconclusionduringaperiodwhentheatomictheorywasnotfullyaccepted.HewroteManychemists,Ibelieve,aredisposedtorejecttheideaofanatom.Andtoadheretothatofequivalentproportionsmerely.Theyfiguretheactofcombinationasakindofinterpenetrationofonesubstancebyanother.Butthisisameremaskingofthefundamentalphenomenon.Thevalueoftheatomictheoryconsistsintitsfurnishingthephysicalexplanationofthelawofequivalents:assumingtheone,thotherfollows;andtheassumingtheactofchemicalunionasDaltonfiguredit,weseethatitblendsharmoniouslywithperfectlyindependentconceptionofanether,andenablesustoreducethephenomenaofradiationandabsorptiontothesimplestmechanicalprinciples..(---amazing!)thusgivingtheinitialideasforchemicalbond!

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BytheLightoftheSilveryMoonS.Arrhenius

Arrhenius,S.(April1896)Ontheinfluenceofcarbonicacidintheairuponthe

temperatureoftheground.TheLondon,Edinburgh,andDublinPhilosophicalMagazineandJournalofScienceSeries5,41,251.(39pages).

Arrheniussworkcanbeconsideredtobethebirthofmodernclimatescience.Hegaveamodelthatisstillbeingusedandhecalculatedtheearthstemperatureforthefirsttime!Itisworthnotingthathewasmostlyconcernedwithice-ages,notglobalwarming!But,usingincompletetheoriesandfewbeamsofmoonlight(astheeditorsnote)ArrheniuscalculatedthewarmingresultingfromdoublingofCO2concentrationinatmosphere,usingacreative,wellguidedapproach.Alongtheway,hedescribedtwomajorconceptsthatarestillbeingusedandrefinednamely,thewater-vaporfeed-backandtheicealbedofeedback.

ArrheniusstheorywasbasedonmeasurementsonIRintensityofmoonbeamsmadebySamuelPierpontLangleywhowastryingtocalculatethetemperatureofmoonusingabolometerandselectingtheIRwavelengthusingsalt-prism.ArrheniususedthisdatatocalculatetheIRabsorptionofentireatmosphericcolumnofCO2andH2O.Theanalysis(byhand,nothingless!)musthavebeenanightmareforthereweresomanyvariables.Langleyhadmademeasurementsovermanynights.Thisimplieddifferingweatherconditions,i.e.,differentamountofH2Oinatmosphere.Italsomeantdifferentelevationsofmoon,i.e.,beamspassesthroughdifferentamountsofCO2andH2O.Yet,ArrheniussuccessfullydeconvolutedthecontributionsfromCO2andH2OandaccountedfortheabsorbancebyCO2.

TheprinciplelimitationofArrheniussdatasetwasthattheinstrumentsatthattimedidnotpermitLangleytomeasuretheCO2absorbanceatthe15range.HeusedbestestimatedatasetforCO2concentrationandcreatedaclimatemodelbasedonEnergybalancetheworkleftoverbyFourierusing:

o RadiativeEnergyexchangesbetween atmosphereandspace atmosphereandground groundandspace

o AccountedforwatervaporincreasewithincreaseinTemperatureo UsedspectroscopicdatatoaccountforIRabsorptionandemissionby

atmosphereo Createdasinglelayermodel(andwasclearlyawareofthe

limitations)hehadtodoallcalculationsbyhand!! Gridded,bylatitudeandseason Accountedforhigherinfluxofradiativeenergyatequatorthan

efflux andthathighereffluxathigherlatitudes

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andenergyiscarriedbyatmosphereandoceancurrentsacrosstoaccountforthedifferences.

o Hetookintoaccountcloudalbedoandbuiltthewater-vaporfeedbackeffectonpurereason.

o Heaccountedforice-albedo.UsingthismodelhecalculatedtheeffectofdoublingofCO2as6oCveryclosetothebestcurrentdayestimate!But,astheeditorspointout,hewasmoreluckythanright.Theretwosourcesoferrorsandeacheffectivelynullifyingtheother:

1. Limitationofspectroscopicdatamissing15micronabsorptionbiasestheresultstothehighside.

2. Limitationsofsinglelayeratmospheremodelclearlythetemperatureisnotconstantacrosstheheightoftheatmosphere.Biasestheresultsonthelowside.

Finally,itisworthnotingthatherecognizedthathumanscouldaltertheatmosphereandthusclimateofearthbyevaporatingthecoalminesintoatmospherebutunderestimatedhumangreedandsaiditwouldtake1000years.

RadiativeTransferG.N.Plass

Plass,G.N.(1956)Theinfluenceofthe15carbondioxidebandonthe

atmosphericinfra-redcoolingrate.QuarterlyJournaloftheRoyal

MeteorologicalSociety,82,310324.By1950sradiativetransferwasafieldofintenseenquiryamongscientistsinvestigatingthephenomenainspace.ItfoundapplicationinearthscienceandsomeseminalworkbyKarlSchwartzchildandJREmdenjumpstartedtheresearch.InEarthScience,understandingradiativetransferhelpsunderstandingtheverticaltemperaturestructureandinpredictingweatherbeyondaday.CallendarusedradiativetransfertointegratebetterspectroscopyandverticalresolutiontoArrheniusscalculations.GilbertPlasspickedupresearchwhenaccuratedataonIR

spectroscopyofCO2andsufficientcomputingpowerwasavailableforhim.Thisallowedhimtodomulti-level,multi-bandradiativetransfercalculations.Hedispensedoffmanyapproximationsthatlimitedtheearlierworks.Healsoaccountedforpressure-broadeneffectonCO2althoughhedidnotaccountforwatervapor.Inthispaper,hiskeycontributionwere:

o DeterminedtheIRcoolingrateo Topoftheatmosphereemission!o AndhowtheabovewereaffectedbychangesinCO2concentration.

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However,hefellpreytosurfacebudgetfallacy:i.e.,notaccountingfortheimbalanceintopoftheatmosphere(i.e.,increaseitsemissivitytoo!)andonlyaccountedforthetemperatureincreaseduetotheincreaseinemissivityofatmosphere(causedbydoublingofCO2)downward,i.e.,towardssurfaceonly.

TheBalanceofEnergyW.D.Sellers

Sellers,W.D(1969)Aglobalclimaticmodelbasedontheenergybalanceofthe

Earth-atmospheresystem.JournalofAppliedMeteorology,8,392-400.

BeforeSellersfamouspaper,ManabeandWetherald(1967)incorporatedthelastbuildingblockstoproduceaproperquantitativeestimateoftheeffectofCO2on

changesintemperature,namely,spectroscopicdataforwatervapor,theeffectsofverticalconvectiononthetemperaturestructureofatmosphereandtheyaddressedtheSurfacebudgetfallacythathadeludedPlasssgrasp.Thus,theyproducedanumericalmodelincorporatingalltheaboveandtheknowledgeaccumulatedtillthentofeedintoapowerfulenoughcomputerandarriveatanestimatethatgainedconfidenceamongthecommunity.ThemodelwasstillaEnergybalancemodel.Sellersadvancedthismodelbyonemorestepandaccountedforsurfaceconvection.Hismodelaccountedfortheice-albedoanditsroleintemperatureandallowednumericalcalculationofice-albedowhichaccountedforice-albedofeedback.

Inthispaper,Sellerspredicted3statesofearth(withconstantsun),onewithnoorverylittlepolarice-caps,anunstablestatewithlargepolaricecapandfinally,astablegloballyglaciatedstateSnowballEarth.Althoughhispredictionofthelaststatewasmoreofacuriosity,todayisbeingarguedthatearthactuallydidgothroughtheSnowballperiod.Finallyhearrivedat3majorconclusions,onesthatareveryrelevanteventoday:o Removingarcticicecapwouldincreasetempby7Cmaxo Decreaseofsolarconstantby2-5%caninitiateanotherice-age.o mansindustrialactivitiesmayeventuallyleadtoaglobalclimatemuchwarmer

thantoday.propheticindeed!