Analysis, Integration and Modeling of the Earth System (AIMES): Advancing the post-disciplinary understanding of coupled human–environment dynamics in the Anthropocene

Analysis,

Integration

and

Modeling

of

the

Earth

System

(AIMES):

Advancing

the

post-disciplinary

understanding

of

coupled

human

–

environment

dynamics

in

the

Anthropocene

David

Schimel

,

Kathy

Hibbard

,

Duarte

Costa

,

Peter

Cox

,

Sander

van

der

Leeuw

*

JetPropulsionLaboratory(JPL),USA b

NASAHeadquarters,USA c_{UniversityofExeter,UK} d_{ArizonaStateUniversity,USA}

ARTICLE INFO

Articlehistory:

Received6September2015

Receivedinrevisedform13February2016 Accepted19February2016

Availableonline10March2016 Keywords:

GlobalEarthSystemScience Modeling

Human–environmentinteractions AIMES

FutureEarth

ABSTRACT

TheIGBPAnalysis,IntegrationandModelingoftheEarthSystem(AIMES)projecthasdevelopedthe

notionofEarthSystemScience(ESS).ESSstudieshowtheplanetoperatesasacoupledsystem of

interacting components,whichproduce emergentbehaviors overand beyondthedynamics ofthe

individualcomponents.ManyclimatemodelsusedintheIPCC's5thAssessmentReport(AR5)include

representationsofthephysicalclimatesystemandthebiologicalcomponentsofthelandandocean

carboncycle.AIMESanditsforerunnerGlobalAnalysisandIntegrationofModels(GAIM)helpedlaythe

groundworkforthisadvance.Subsequently,AIMEShasbeeninstrumentalintheevolutionofclimate

modelsintoEarthSystemModels,promotingdialogbetweentherelevantcommunitiestoensuregreater

consistencyintheIPCCassessmentprocess.

Today,societyfacesinterconnectedchallengesincludingclimatechange,financialcrises,foodsecurity,

governanceofpandemics,andenergysufficiency.Thisrequiresdecisionmakerstounderstandsystemic

risksforwhichtheavailabletoolsprovideinsufficientguidance.AIMESistargetingtoimprovelinksof

sciencewithstakeholdersinsocietytostimulateappropriatesocietalresponses.UnderFutureEarth,

AIMES prioritizes the understanding and modeling of human–environment interactions in the

Anthropocene,focusingongatheringconsistentdataonbiophysicsandsocioeconomics;lessonsthat

canbelearntfrompasthuman–environmentinteractions;andthemodelingofplanetEarthasacomplex

systeminwhichhumanbeingsareinternalcomponentsratherthanexternalactors.Keyoverarching

themes includeland-usechangeandthecharacterization andforecastingof criticaltransitions (or

“tippingpoints”)intheEarthSystem.

ã2016TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-ND

license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

1.Introduction—thelegacyfromGAIM

Thisdocument providesthreemajoravenues ofinformation. First, we describe the legacy and heritage of AIMES, we then provideinsightintohowAIMEShascontributedtoEarthSystem Science(ESS)throughobservations,human/environmental inter-actions,predictionandmodelevaluationandfosteringintellectual collaborationacrossthenaturalandsocialsciences.Thediscussion nextprovidesanoverviewofhowthefutureofAIMESwillevolve withglobalchangescienceandcomplexsystemsascornerstones of the future. We then conclude with the need for multiple

pathwaysofsciencetoapplicationforthenextgenerationofEarth system science.Moreinformation aboutAIMES canbefoundat www.aimes.org.uk.

TheGAIMTaskForcebeganin1993withthegoalofadvancing thestudyofthecoupleddynamicsoftheEarthsystemusingboth observationaldataandnumericalmodels.GAIMrealizedthatto developintegratedmodelsoftheEarthsystem,itwasnecessaryto evaluatemodelperformance inthecontextofcomponentEarth system disciplines:atmospheric, oceanicand terrestrial.Atthat time,itwasclearthatmodelingthecarboncyclewasamajorgapin climatesystemmodelingandGAIMundertookaseriesofhighly influentialactivitiestofillthatneed.TheevolutionofGAIMcanbe summarizedintwophases:(1)astrongfocusonindependent sub-system analysesof thecarboncyclefrom1993-ca2000, during whichseveralmodelintercomparisonactivitiesevolvedincluding * Correspondingauthor.

E-mailaddress:[email protected](S.v.d.Leeuw).

http://dx.doi.org/10.1016/j.ancene.2016.02.001

2213-3054/ã2016TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

ContentslistsavailableatScienceDirect

Anthropocene

thePotsdamNetPrimary ProductivityProject (PIK-NPP),Ocean CarbonModelIntercomparisonProject (OCMIP),and the Atmo-sphericTracerTransportModelintercomparison(TRANSCOM);(2) atransitionperiodfromca.2000 2003wheretheoriginalgoals werere-visitedand activities wereinitiatedtoaddressbroader Earthsystemquestions,which ledtotheinitialdevelopmentof coupledcarbon–climatemodels(e.g.C4MIP).The first phase of GAIMocean(Orr,1999,Orretal.,2001),atmospheric(cfDenning etal., 1999;Gurneyetal.,2000,2002,2003)andterrestrial(Cramer etal.,1999;Heimannetal.,1998;Olsonetal.,2001;Zhengetal., 2002)intercomparisonprojectscontributedsignificantadvances in our ability to quantify carbon pools and _fluxes and to discriminate between uncertainties in and between model formulationsandsparsedatasets.Forinstance,theTransComor “Atmospheric Traces Transport Model Intercomparison Project” wasabletoquantifyhowdifferencesinverticalmixingcontribute tovariablemeridionaltransportintheatmosphere(Denningetal., 1999).

Thenext phaseofGAIM recognizeda changinginternational scientificlandscapeanddecidedthatthetimewasripetoaddress broader Earth System objectives. The Coupled Climate Model Intercomparison Project (C4MIP) and Earth System models of IntermediateComplexity(EMIC)wereinitiatedtointegrateocean, atmosphere and terrestrial models of the carbon cycle and simplified formulations of Earth system dynamics over paleo-timeframes,respectively.Concurrenttothedevelopingthemeof earth system analyses was the development of a new Global CarbonProject(GCP) whose goalis tounderstandthehuman– naturalcarbon systemand itsassociated feedbacks.Therehave beenanumberofothersuccessfulactivitiesthatwereinitiatedby GAIM,orthroughGAIMcollaborationwithotherprograms.The GlobalSoilData Task (2000)was aninternationalcollaborative projectledbytheInternationalGeosphere–BiosphereProgramme DataandInformationSystem(IGBP-DIS)todevelopanimproved globaldatabaseofsoilcharacteristics.TheSoilDataSystemallows userstogeneratesoilinformationandmapsforgeographicregions atsoildepthsandresolutionsselectedbytheuser.Derivedsurfaces ofcarbondensity,nutrientstatus,water-holdingcapacity,andheat capacityareprovidedformodelingandinventorypurposes.BIOME 6000(TEMPO,1996;Jollyetal.,1998;DeNoblet-Ducoudreetal., 2000),wasanotherpartneredactivitywithIGBP-DIS,IGBP-GCTE

andIGBP-PAGES.TheaimofBIOME6000wastoassemblepollen datafor6000and18,000yearsbeforepresent(yrB.P.),andtouse thesedatatoconstructglobalmapsofvegetationforthesetime periods,usingastandard,objective“biomisation”techniquebased ontheclassificationofplanttaxaintoplantfunctionaltypes.The BIOME6000activityhasgeneratedglobalvegetationand mega-biome reconstructions for the mid-Holocene and last glacial maximumaswellasregionallandsurfaceandaeoliantransport anddepositiondatabases.

In this article a summary of AIMES research areas and accomplishments is towards presented and its importance explained.Section2detailsinfoursub-sectionsthecontributions of AIMES for integrated human–environmental research on (i) present timescales using Earth System Observations, (ii) past timescaleslaunchingandnowcollaboratingwiththesisterFuture Earthproject IHOPE(iii)futuretimescalespredictingchangesin theEarthSystemthroughEarth-SystemModelingand(iv)forming a new generation of Earth System Scientists through young researcheropportunitiesandworkshopsundertheYoungScholars Network(YSN).InSection3theplaceofAIMESwithintheFuture Earth network of communities is explained, particularly in contributingtowardsa paradigmshiftindeliveringmore trans-disciplinaryresearchandinmovingforwardtoafull understand-ingoftheEarthasacomplexsystem.

Finally,asummaryofthelessonsfromAIMESresearchareasis presented ina waythat sharessuchinvaluableexperienceand givesassuranceofAIMESuniquestandpointto,fromwithinFuture Earth,articulatedifferentprojectsfromvariousrelateddisciplines, todelivera novel and post-disciplinaryintegrated approach to study theEarth System and thecauses and implications of its changesdueto,andupon,humansystems.

2.AIMESresearchareasandrecentaccomplishments

2.1.DatafortheAnthropocene:EarthSystemObservationsandthe MertonInitiative

ObservationsarecentraltotheEarthSystemScienceenterprise, providing the phenomenological basis for the development of theory,quantitativeinformation formodelbuildingand evalua-tion,and detectionofchange.EarthSystem Scienceinherits an

Fig.1.UnevenlatitudinaldistributionofFLUXNETsites(redbars)relativetoestimatedzonalmeanGrossPrimaryProductivity(GPP,bluelinesandlightblueuncertainty shading),andtotallandcarbon(orangelineandpinkuncertaintyshading)(Schimeletal.,2015).

observationsystemlargelybuiltarounddisciplinary,regionaland practical constraints, and attempts to repurpose this for Earth System Science. Efforts such as GEOSS have led the way in attemptingtorationalizethissystem,conductgapanalyses,and developthebestpossibleproductstofillthegaps.Asnewscience questions emerge, however, studying the dynamics of coupled subsystemsseemstorequireanewlevelofcoordinationbetween disciplinaryorprocess-focusedobservations.AIMES,togetherwith numerous partners, organized a workshop at Merton College, OxfordinSeptember2011tostudythecurrentstateanddesirable futureofEarthSystemobservations.Thereportincludedanumber ofimportantissues,assummarisedbelow(Schimeletal.,2012). First, there is a strong bias in observations towards the accessible,leadingtoobservingsitesbeingcorrelatedwithdense humanpopulations,andmildclimates(seeFigs.1and2).Onland thetropics and high latitudes,and in the oceans theSouthern Ocean and other blue-water regions of strong physical and biological activity (ice margins) are under-sampled. These are regionsofstrongEarthSysteminteractionandlikelylocationsfor tippingpoints(Schimeletal.,2015).Thesemeasurementbiases contributeverydirectlytomodeluncertainty becausethemost sensitiveregionsarethereforealsotheleastwell-constrained.

Second,remote sensingplaysa critical role in EarthSystem science,providingaglobalperspective,datathatmaybeapplied acrossarangeof scales,andongoing time series.However,the Merton report notes that space-based data are usually most powerfulinconjunctionwithinsituobservationsandthatthere are many opportunities to develop “linking observations” that increasethevalueofbothvantagepoints.Identifyingandmaking theselinkingobservationscanincreasetheaccuracyofthe space-based observations and extend the impact of the in situ observationsbyallowingtherigoroususeoftheremotesensing productsinextrapolation.

Third,the increasingly intense interactions between human andnaturalsystemsareimperfectlyobservedatbest.Inthisarea, thedisciplinaryboundariesareparticularlyhigh,thecorrectscales tocoupledobservationsarenotobvious,modelsareprimitiveand providelittleguidanceandcorrespondinglytheopportunitiesfor rapid progress are large. Linking observations of human and natural systems can lead to rapid progress, and may allow

falsificationof someof thewidelydivergentideas,nowlargely ungrounded in data, about how these interactions proceed. Foundationsfor thisnascent areaofobservational scienceexist relatedtolanduseandlandcoverchange,demography,agriculture and water resources. Merton workshop participants saw the further development of this idea as essential to the coupled human–environmentmodelingenterpriseaswell.

2.1.Learningfromthepast

TwoimportantlimitationsoftheinitialAIMESapproachare(a) that itonlytakestherecentdynamicsof theEarthsysteminto account, and (b) that it does not consider the role of societal dynamics(Crumley,2000).Tomitigatethis,itdevelopedtheIHOPE project, which studies the long-term trajectories of integrated human–environmental systems,basedonarchaeological, paleo-environmental,anthropologicalandhistoricaldata( http://ihope-net.org/about/)inordertobeginconsidering:

& Very slow, long term dynamics not observable at shorter timescales.Thesecanbeincremental(asinculturalchanges)or anaccumulationofminorshocks(asintectonics);

& Amuchwiderrangeofsystemstates.Reconstructionofsystem dynamicsbasedonshortperiodsofobservation(thelast50– 150years)dealswithstates considerablyaffectedbyhuman activities,excludingnature-dominatedstates

& Thesecondorderdynamicsofsocio-environmental co-evolu-tion: structural changes in thedynamics governing that co-evolution as societal and environmental dynamics became moreintertwined.

InIHOPE,societalchangesareexploredfromfirstemergenceto transformation, through the dual lens of both influencing and being influenced by environmental change. The data and informationfromthepastareusedtobuilddynamicalmodelsof theprocesseswhichshapedthatco-evolution,andthosemodels areusedtolearnforthefuturebyexperimentallymodifyingthem, stressingthemandotherwisestudyinghowthedynamicswould playoutunderrangesofdifferentcircumstances(vanderLeeuw et al., 2011; Costanza et al., 2012,). Comparing thesescenarios

providesinsightintothestructure,strengthsandweaknessesof thedynamicalsystemsinvolved,includingtheirpotentialtipping points.

TheMayaSimmodel(https://www.openabm.org/model/3063/ version/4/view),forexample,examinestherelationshipbetween populationgrowth,agriculturalproduction,pressureonecosystem services,forestsuccession,valueoftrade,andthestabilityoftrade networks. It calculates biophysical variables for precipitation, waterflow,andnetprimaryproductivity,andthesearethenused to estimate forest succession, agricultural production, and ecosystemservices. Settlementagents interact with thespatial landscapetogenerateagriculturalyieldthroughcropping,derive benefitfromlocalecosystemservices,andgeneratetradebenefits withintheirlocaltradenetwork(Heckbert,2013).Thecombined benefits of agriculture, ecosystem services and trade drive demographicgrowthincludingmigration.

Bymodifyingthemodelparameters(temperature,hydrology, areaavailable for cultivation, crops, population, etc.),different scenarios canbeelaborated thatexplore differentstates ofthe systemduetodifferencesinthebalancebetweenresourcedemand andconsumption:

1.Ampleresources/lowdemandcausesrapidadaptationsofthe systemtoexploitexcessenergy.

2.Ampleresources/moderatedemandleadstoastableperiodthat isabletoadaptorwithstandchangesinresourcesordemand. 3.Moderate resources/low demand causes changes in social

organization,populationgrowth,territorialcontrol.

4.Moderate resources/moderate demand generallyleads to an unstableperiod,“quick-fix”changesindemandorresources. 5.Moderateresources/highdemandcausesrapidadaptationsto

declining supply, and if maintained for a longer time,

consumption of potential future resources to meet present needs.

6.Fewresources/highdemandmakesthesystemhighly suscepti-bletoanyclimatic,socialorenvironmentalchange.

Bylocatingindividualsettlementsinthisdemand/consumption frameworkonecanbegintoassesstheimpactoflocal environ-mentalcircumstancesonthe sustainability/resilience/vulnerabili-ty ofthesettlements, thuslayingthefoundationfora rangeof different co-evolutionary scenarios of the settlement network (Fig.3).

IHOPE,whichisnowanindependentFutureEarthcoreproject, aimstocomparecasestudies,suchasAustralianhunter–gatherer societies,small-scale dry-farmingand irrigationsocietiesin the southwestoftheU.S.A.andnorthernMexico,morecomplexchiefly societies of the Maya area and the Roman Empire. Such comparisonsenablea moregeneralassessmentof thevariables impactingontheinteractionofdifferentsocietalstructureswith theirenvironment.

2.2.Predictingthefuture:developmentandevaluationofearthsystem models

AIMES, withits forerunner (IGBP-GAIM), and WCRP partner

(the Working Group on Coupled Modeling, WGCM), have been

instrumentalintheevolutionofclimatemodelsintoGlobalEarth SystemModels(ESMs).AIMES,incoordinationwiththeWGCMand theIntegrated Assessment Modeling Consortium (IAMC) devel-oped the Representative Concentration Pathways (Moss et al., 2010;VanVuurenetal.,2011),wherebypolicy-drivenmitigation scenarios were provided by the IAMC to catalyze the climate modeling work for the IPCC’s Fifth Assessment Report (AR5)

Fig.3. Resultsofaregressionanalysisoverthreeprincipalfactorsfordifferentgroupsofsettlements.EachdotisaMayacity(andthesurroundinglandscapeonwhichit depends),andtheyellowcirclesindicatefourdifferentbandsofresourceavailabilityandconsumption.(PublishedwithpermissionbyJ.Gunn).

(Fig. 6). The AR5 was the first coordinated intergovernmental assessment that included carbon cycle emissions and concen-trationstodiagnosecarbon cyclefeedbackstotheEarthsystem (Hibbard et al., 2007). The coordination between the climate modelingcommunitiesandtheIAMCledtotheactive develop-mentofconsistentlandcover/landuseandemissionsdatabasesfor theAR5(Hurttetal.,2011;Lamarqueetal.,2009)(Fig.4).

AIMESsupportedthedevelopmentandevaluationofoceanand landcarboncyclecomponents,andcontinuestodosothroughits MAREMIP (http://lgmacweb.env.uea.ac.uk/maremip/index.shtml) andiLAMB(http://ilamb.org)activities,respectively.AIMESandits Scienti_fic Steering Committee (SSC) members have led the developmentandintercomparisonoffullycoupledclimate–carbon models(Friedlingsteinetal.,2006;Hibbardetal.,2007;Aroraetal., 2013;Brovkinetal.,2013).Asaresultoftheseefforts,theIPCC5th AssessmentReport,orIPCCAR5,containsresultsfromESMs(i.e coupledclimatecarbon-cycle models). AIMES hascontinued to contributetothedevelopment,evaluationanduseofEarthSystem Models,asevidencedbytherecentexamplesbelow:

(a)EvaluationofcarboncyclesimulationsintheIPCCAR5Earth systemmodels

AIMESwascentraltothekeystudiesthatanalyzedthecarbon cyclesimulationsproduced bytheEarthSystem Models(ESMs) used in the IPCC AR5 as outlined by Hibbard et al. (2007), producinginfluentialpublicationsontheevaluationofthemodel againstthe historicalrecord (Anav etal., 2013), theanalysis of climate–carboncyclefeedbacks(Aroraetal.,2013),andtheimpact ofchangesinland-use(Brovkinetal.,2013).

(b)Assessing thevulnerabilityof tropicalrainforests toclimate change

AIMES was involved in two high-profile papers that re-examined thevulnerability of tropical rainforests (especiallyin Amazonia)toclimatechange.Thefirstoftheseshowedthatthe year-to-year variation in atmospheric CO2 is correlated with projected losses of tropical land carbon under climate change, acrosstheensembleofEarthSystemModels(Coxetal.,2013).This enablestheobservedyear-to-yearvariationinatmosphericCO2to beusedasanEmergentConstraintonfuturetropicalcarbonlosses duetoclimatechange—suggestinglossesofabout50GtCperCof warminginthetropics(seeFig.5).Thesecondpaper(Huntingford etal.,2013)indicatesthattheAmazonianrainforestistherefore likelytoberobusttoCO2-inducedclimatechange,butonlyifCO2 fertilizestreegrowthinthemannercurrentlyassumedinESMs

(c) Intercomparisonofphytoplanktonsuccessionandphenology (MAREMIP)

AIMES supported the MAREMIP project in comparing the performance of marineecosystem models.Recently, thespatial and temporalrepresentationofphyto-planktonfunctionaltypes (pPFTs) in four different Dynamic Green Ocean Models was compared to phytoplankton distributions derived from two independentsatelliteestimates(Vogtetal.,2013).Modelswere foundtosimulatediatomdominanceovera widertemperature andnutrientrange,whereassatellitesconfinediatomdominance toanarrowernicheoflow-intermediateannualmeantemperature (annualmeanSST10C),butallowfornichesindifferentrangesof surfacenitrateconcentrations.Thedifferencesinthe representa-tion of diatoms among modelsand thecomparison to satellite estimateshashighlightedtheneedtobetterresolvephytoplankton successionandphenologyinthemodels.

2.4.Developinganewgenerationofearthsystemscientists:theyoung scholarsnetwork

AIMES,incollaborationwiththeUK,heldfiveYoungScholar’s Network(YSN)i_{workshops.TheYSNgoalwastofoster} collabo-rations amongYoungScholarsonintegrative researchtobetter understandtheroleofhumansinperturbingbiogeochemistryand climate, connecting these researchers across disciplinary and geographic boundaries. Since 2005, the AIMES YSN has been extremelysuccessfulinbridgingmultidisciplinaryand geographi-callywidespreadyoung,andearlycareerscientificandscholarly communitiestowardsthedevelopmentandfuturecollaborationof trans-disciplinaryunderstandingofEarthsystemscience(Scholze etal.,2005).AlloftheAIMESYSN’srequiredparticipationfrom physical,biologicalandsocialscientistcommunitiesaswellasthe humanities.ThefurtherdevelopmentoftheYSNconceptunderthe umbrellaofFutureEarthisahigh-priorityforAIMES(seebelow) (Scholze,2007).

3.AIMESunderfutureEarth

3.1.Theneedforaparadigmshiftinglobalchangeresearch

ThelastthirtyyearsofGlobalChangeResearchhasyieldeda patchwork ofinformation aboutmanyenvironmentalaspectsof thecurrentEarthSystem.Thatpatchworkhasmanystrengthsand weaknesses.Currentunderstandinghasbeengainedthroughthe effortsofscientistsmainlyworkingindisciplines,orsmallclusters ofdisciplines;yetsomanychallengesandresearchfrontiersstill

Fig.4.Trajectoriesoffourmitigationpathways,orrepresentativeconcentrationpathways(RCP’s)developedbytheintegratedassessmentcommunityincoordinationwith theclimatemodelingcommunityfor(a)radiativeforcing(W/m2

),(b)CO2,(c)CH4;and(d)N2Oemissions.Similartrajectoriesweredevelopedforotherconcentrationsand othergreenhousegasses(fromVanVuurenetal.,2011).

remain.EvencurrentEarthSystemScienceisinsufficientlyholistic forthechallengesoftheAnthropocene.Whiletheenvironmental and societal dynamics have been co-evolving together over millennia, relativelylittlescholarship hasexplored this. Indeed theenvironmental and the societaldomainhave until recently beenseenasseparableforthepurposesofmostresearch.Scale, whichisamongthefirsttopicsthatIGBPexplored(Rosswalletal., 1988),remainsafundamentalchallenge.

Mostofourunderstandingisgainedatone,twooratmostthree scalesintimeand/orspace,andwelacktheknowledgetodefine thetime/spacescalesatwhichhumanandnaturalsystemsinteract strongly or weakly. The Complex Adaptive Systems approach fundamentalforunderstandingthedynamicsoftheGESS,hasbeen applied patchily. Therefore AIMES 2.0 is adopting a Complex Adaptive Systems perspective that crosses sectors, scales and disciplines(vanderLeeuw,2013).

AIMESwillworktodevelopanintellectualframeworkinwhich human–natural systems interactions are intrinsically coupled. McGladehasargued (1995): “There is nonatural (sub) system, thereisnosocial (sub)system,thereareonlyinteractionsinan

integrated system”. Soin order tounderstandand manage the Anthropocene,wewillconceiveofthe(Global)EarthSystemasa multi-scaled Complex Adaptive System that encompasses all interactionsonEarth,whetheramongnaturalsubsystems,among societalsubsystems,orbetweennaturalandsocietalsubsystems. We believe that thekey issue is to extend theESS concept to includehuman-kindasinternalcomponentsratherthanexternal actors.

3.2.UnderstandingandmodelingplanetEarthasacomplexsystem

In general, a system is de_fined as a conceptualisation of a portionof realityin terms of a setof interrelatedelements.In general, theelementscanbemolecules,organisms, geophysical factors,social entities, or EarthSystem sub-systems. The inter-relations, inter-linkages and couplings betweenthese elements may also have very different manifestations (economic trans-actions,flowsofmatter,energyorinformation,causalrelations, etc.),andoftendisplayemergentproperties.Hencethenotionthat “thewholeismorethanthesumoftheparts”.

Fig.5.Emergentconstraintonthesensitivityoftropicallandtowarmingarisingfromtheobservedinter-annualvariability(IAV)inthegrowth-rateofatmosphericCO2(Cox etal.,2013).(a)Climatesensitivityoftropicalland-carbon(ãLT)versusthesensitivityoftheCO2growth-ratetotropicaltemperature,foreachofninecoupledclimate-carbon cyclemodels.Thered-dottedlineshowsthebest-fitstraight-lineacrosstheC4

MIPmodels(blackletters).Theredlettersrepresentatestofthisrelationshipagainstthethree HadCM3Censemblemembers.Theverticaldot-dashedlineindicatestheconstraintontheobservedIAVoftheCO2growth-rate.(b)Probabilitydensityfunction(PDF)forthe climatesensitivityofãLTderivedfromapplyingtheIAVconstrainttotheacross-modelrelationshipshowninpanel(a).Theredlineshowsthe“prior”PDFthatarisesfrom assumingthatalloftheC4

MIPmodelsareequallylikelytobecorrectandthattheycomefromaGaussiandistribution.

Fig.6.schematicshowingthetransitionfromthekeyAIMES1.0projectstotheAIMES2.0VirtualInstituteforthestudyofCoupledHuman-EnvironmentDynamicsinthe Anthropocene.Currentandfutureprojectsareorganizedintothefourthemesidentifiedbythecolorcoding.

Thefunctionalcouplingsbetweenhumanandnaturalfactors are increasingly becoming powerful co-determinants of the dynamics of the whole Earth System, yet our theoretical and empirical tools to address this remain limited. The obvious exampleisthecouplingbetweentheimpressivebuildupofCO2 generatedbyhumanactivities(fossilfuelscombustion,generation ofaerosols,cementmanufacture,deforestation,andothers)and global climate change, that is in turn reverberating back into humanwell-being.

Manysourcesofuncertaintyariseincomplexsystems.Someof thesearereduciblewithmoredataandadditionalresearch,suchas theuncertaintyduetorandomprocesses(amenabletostatistical orprobabilisticanalysis),orthatduetoignorance(becauseoflack ofdataorinappropriatedatasets,incompletenessinthedefinition of the system and its boundaries, incomplete or inadequate understandingofthesystem).Sourcesofuncertaintyarisingfrom chaoticandcomputationallyirreduciblebehaviorarereviewedin Beckage et al., 2011). Dealing with this kind of irreducible uncertainty is one of thesignificantepistemological challenges ofESS(ModvarandGallopín,2005).

IGBP-AIMES,anditsforerunnerIGBP-GAIM,hasbeen instru-mentalintheidentificationofclimate“tippingpoints”thatcould resultinabruptand/orirreversiblechanges(Lentonetal.,2008). AIMES2.0willpromoteresearchontippingpoints,withthegoal of providing techniques that could beused across the whole-rangeofdisciplinesthatwillcontributetoFutureEarth—fromthe economicsofmarketcrashestothedynamicsofhumanmigration. 4.Conclusions:Earthsystemscienceasapost-disciplinary effort

ReflectingonwhenworkbeganonGAIMandAIMESsince1990, these integrative core projects have cultivated an increasingly post-disciplinarycommunity ofscholarship.WhenGAIMbegan, thegrouphadtobridgeseeminglyvastdifferencesinperspective, scale,culture,andtools,betweentheearthandlifesciences.

Thecommunitiesthatcametogetherapproachedprocessesat differenttimescales,overdifferentspatialextentsfromorganisms totheglobe,andhaddifferentobservationalresourcestodrawon. AsAIMESbegan,itfacedsimilarchallengesintegratingthesocial sciences and humanities, even to the extent of referring to “scholarship”ratherthan“science”initsactivities.

AIMES has taken a problem-oriented approach, focusing on topicssuchastherelationshipbetweenfuturefossilemissions(a human process) atmospheric concentrations (dependent on physicsandbiology)andclimate(largelyphysics);andtheimpact of climate variability on societal development (paleoclimate, archaeology,history—allcollaboratingtounderstandgovernance). Disciplinaryknowledgewascentralandcrucialinthesestudies, butoperationally,theAIMESgroupsoftenfoundthetrappingsof thediscipline,theirculture,assumptions andpriorities,tobea hindrancetoopendiscussion,leadingtomisunderstandingsasa resultofunstatedassumptions.However,withcommitmentand goodwill,theseissues diminishedinimportanceand theAIMES groupslearnedto“checktheirdisciplinesatthedoor”,bringtheir knowledge,world-viewsandperspectives,butbeveryclearabout assumptions and presumptions associated withthose perspec-tives. The understanding achieved through a problem-oriented approachisnowbeingworkedonincollaborative, interdisciplin-arywaystofindsolutions toimproveourunderstandingof the Earth-system.Infact,manyoftheissuesinEarthsystemscience areintegrated,wholetopicsthatdonotmapontoourmedieval sortingofknowledgeintodisciplines.

Studyingmanyof theinteractionsand feedbackswithin the human–natural Earth systemrequires individuals and teams to possessknowledgethatspansmanytraditionalareas,andtohavea

perspectiveofthewholesystem thatdoesnotcurrentlybelong uniquelytoanyoftherecognizeddisciplines.Astheworldchanges, thesocio-environmentalproblemsthatmustbeaddressedinthe transitiontosustainabilitydivergeincreasinglyfromthe knowl-edge paradigmsofacademia and requireindividuals andteams that canintegrateknowledgeacrossdisciplines,time andspace scalestoaddressthemulti-scaledenvironmentalchallengesofthe nextcentury.

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