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JohnA.Church1,Ma0hewD.Palmer2andSusanWijffels11CSIROOceansandAtmosphere,Hobart,Australia2MetOfficeHadleyCentre,Exeter,UnitedKingdomOCEANSANDATMOSPHERENATIONALRESEARCHFLAGSHIP
AssessmentoftheEarth’sEnergyandSeaLevelChanges
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vonSchuckmannetal[2016]
Earth’senergyimbalance:thedriverofglobalclimatechange
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PalmerandMcNeall[2014]vonSchuckmannetal[2016]
SurfacetemperatureisaweakindicatorofEarth’senergyimbalanceondecadalJmescales
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PalmerandMcNeall[2014]vonSchuckmannetal[2016]
OceanheatcontentchangeisareliableonEarth’senergyimbalanceondecadalJmescales
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Oceansabsorbed>90%oftheenergystorageandaccountforathirdofradiaJveforcing
5IPCCWGICh3&13
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TheArgoArrayprovideshigh-quality,globalcoverageto2000m,fromabout2006• Mapoceanheatcontentandstericsealevel• Qualitycontrolofdataimportant.Bewareofbiasesfromhistoricaldatabases.
• Coveragenotcompletepriorto2006
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ArgoheatcontentesJmatestolate2015SteadyheaJngofocean,parJcularlySouthernOceanandfrom300mto2000m
7|
Wijffelsetal.2016
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DeepOceanWarming• Sincethe1990s,whensufficientdeep-oceanobservaUonshavebecomeavailabletoallowanassessment,thedeepoceanbelow3000mdepthhaslikelywarmed.
SPM-4andChapter3.2:DeepOceanWarming
Fig3.3Meanwarmingratesbelow4000mcenteredon1992–2005.SUppledareasnotsignificantat95%.Thickblacklines-RepeatoceanographictransectsusedtoesUmatewarmingrates.DatafromPurkeyandJohnson(2010).
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Totalenergystorageconsistentwithclimatemodelensemble(butsignificantvariabilitybetweenmodels)
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• Upper2000mofoceansampledbyArgo=0.5-0.65Wm-2
• Fulloceanarea&deepocean=0.65-0.8Wm-2
• 0.7–0.86Wm-2incllithosphere,cryosphere,atmosphere
ModelresultsfromChurchetal.2013,IPCCWGIAR5Ch13
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Rateofheatstoragehasincreased,withsignificantstorageindeepocean
Gleckleretal[2016]
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Progresstowardsadeepoceanobservingsystem–needtomaintainGO-SHIPandextendArgotofulldepth
GO-SHIPnowprovidesobservaUonsinthedeepocean(>2000m)
Straw-planfor5x5degreeDeepArgofloatarray0-4000mand0-6000mfloatsarecurrentlybeingdeployedinpilotstudies
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Globalsealevelandenergybudgetslinked
RelaUvesealevelisalsoaffectedbyoceandensityandcirculaUon,landmovement,anddistribuUonofmassontheEarth
Fig13.1
Warming(cooling)oftheocean(thermalexpansion/contracUon)
Changeinmassofglaciersandicesheets(BarystaUc)
Changesinliquidwaterstorageonland(BarystaUc)
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SealevelisconJnuingtoriseatafasterratethantheaverageduringthe20thcentury
Timeofemergenceforregionalsea-levelchange13|
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Thetrendisnotuniformglobally
Timeofemergenceforregionalsea-levelchange14|
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ThestrongElNiñohasresultedinhighsealevelanomaliesintheeasternPacificattheendof2015
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AswellasthermalexpansionandglaciercontribuJons,theGreenlandandAntarcJcIceSheetsarelosingmass
Timeofemergenceforregionalsea-levelchange16| Velicognaetal.2014
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PastclimatevariaJonsimportantforsealevelrisepriorto1950–Anthropogenicforcingdominatesa`er1970
Slangenetal.,inreview
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Conclusions• OceanheatcontentcriUcalelementofkeepingtrackofclimatechangeandunderstandingtheEarth’sradiaUonandsealevelbudgets.
• ArgoallowsmuchimprovedesUmatesofupper(<2km)oceanheatcontent-needtoextendtofulldepthandfulloceancoverage,complementedbyrepeatsecUons.
• Unequivocalwarmingoverdecades–EsUmatesconsistentwithCMIP5modelesUmatesofoceanheatcontent.
• SealevelconUnuingtorise;StrongElNiñoinlate2015resultedinhighersealevelsintheeasternPacific.
• ContribuUonsfromthermalexpansionandtheaddiUonofmassfromglaciersandicesheets.
• Anthropogenicclimatechangedominatesrecentrise.• HeatcontentandsealevelarecriUcalmeasuresofefficacyofmiUgaUon.
• Longtermcommitment!18|
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InsitudatasuggestsreprocessedalJmeterdatahassmallertrendandaposiJve(notsignificant)acceleraJon(ratherthanadeceleraJon)
Watson et al. 2015
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• ObservaUon-basedesUmateNocreatedbyaveragingsatelliteandAMIPsimulaUons
• Goodagreement(r=0.82)withensemblemeanofCMIP5coupledmodels
• VariaUonsdominatedbyvolcanicerupUons(Agung1963,ElChichon1982andPinatubo1991)
• AbsolutevaluesofNfordifferentperiodsinreasonableagreementwithCMIP5andIPCC
Smithetal.2014
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Improvedunderstandingof20thcenturysealevelchangeObservedcontribuUonsexplainobservedGMSLR1993-2010
DatafromTable13.1
Figure13.7
Anthropogenicinfluence
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Measureoceanmassanditscomponents–significantuncertainJesremainCompareoceanicandgravitaJonalesJmateofregionaloceanmasschange
Diengetal.2015Purkeyetal.2014
CanwebackouticesheetandlandwatercontribuUons?(e.g.Reageretal.2016)
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AlJmeterandstericsealeveltrends2006to2014
Timeofemergenceforregionalsea-levelchange23|
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DifferencesbetweenAlJmeterandsteric(0-2000m)trends–meanremoved
Timeofemergenceforregionalsea-levelchange24|
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PalmerandMcNeall[2014]vonSchuckmannetal[2016]
TheglobaloceandominatestheenergybudgetonJmescales>1year
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RadiaJveforcing,climatefeedbacksandstorageofenergywithintheclimatesystemareconsistentwiththelikelyrange
ofclimatesensiJvity
Box13.1,Figure1IPCCAR5,Box13.1Fig1,Churchetal.2013