Download Systems Thinking and Modeling Climate Change

Systems Thinking and Modeling Climate Change
Amy Pallant, Hee-Sun Lee, and Sarah Pryputniewicz
Youknowtheeffectsoftheproverbialbutterflyflappingitswings.Butwhatabout
anautomobiledriver?Canasingledriver’sactionsaffectEarth’sclimate?Earth’s
systemsarecomplexandfullofsurprisinginterdependencies.Howdowehelp
studentsunderstandthosecomplexitiesandseekanswerstotheautomobile
question,consideringcumulativeandglobaleffects?Oneapproachistoemphasize
systemsthinkinginscienceeducation.
Systemsthinkingsuggeststhatyoucanbestunderstandacomplexsystemby
studyingtheinterrelationshipsofitscomponentpartsratherthanlookingatthe
individualpartsinisolation.Asystemsapproachhelpsstudentsunderstand
interrelatedelements,feedbackloops,andinthiscase,afocusonthewholeEarth
(CenterforEcoliteracy2012).Withongoingconcernabouttheeffectsofclimate
change,usinginnovativematerialstohelpstudentsunderstandhowEarth’ssystems
connectwitheachotheriscritical.
Modeling Earth's climate
ThisarticledescribestheHigh‐AdventureScienceonlineclimatechangecurriculum
called“ModelingEarth’sClimate”developedattheConcordConsortium(see"Onthe
web").Thisfree,innovativecurriculumincorporatesdynamiccomputermodels
developedintheNetLogomodelingenvironment(see"Ontheweb")thatenable
studentstovisualizethecomplexinteractionsrelatedtoclimatechangescience.The
modelsaredesignedtoallowstudentstochangevariablestohelpthemdiscover
howtheindividualpartsrelatetothewholesystem.Whilewedon'texpectthe
studentstounderstandeverysinglevariablethataffectsclimatechange,this
approachhelpsstudentsmakesenseofhumaneffectsonEarth’ssystem.
The models
OurmodelsareidealforexploringEarthsystemscienceandhumanimpactonthe
Earth.Themodelssimulatechangesinasystemandarebasedonmathematical
algorithmsthatapproximatefundamentalphysicallaws(PallantandTinker2004).
Researchshowsthatcomputationalmodelsandsimulationsallowstudentsto
understandthroughexplorationthebehaviorofsystemsthataredifficultto
understandbyothermeans(FeurtzeigandRoberts1999;Horwitz1999).Muchas
scientistsdo,studentscanexperimentwithmodelsbycontrollingconditionsatthe
start(parameters)andduringarun;theycanexplorecauseandeffectbecausethey
canobservethechangesinthemodelsthatemergefromfundamentalscience‐based
rules.Themodelshavevividgraphicsandrunquickly,sostudentscanrunmultiple
experimentstogaininsightsbycarefullyobservingchangestothesystem.Thus,
studentscanlearnbothcontentandtheprocessofsciencebyexperimentingwith
themodels.
IntheModelingEarth’sClimatecurriculumstudentsbeginbyusingacomputer
modeltoexploretheeffectofcarbondioxideonglobaltemperature.Themodel
helpsstudentsseehowcarbondioxidetrapsinfraredradiation,inturnincreasing
thetemperature.StudentscanincreaseordecreaseCO2amountsinthemodeland
observehowthechangesaffectthesystembyinterpretingtheoutputgraphtothe
leftofthemodel(Figure1).Byexperimentingwithextremes—addinglotsofCO2or
removingmostoftheCO2—andpayingattentiontotheresultinggraph,students
discoverforthemselvestherelationshipbetweenatmosphericcarbondioxideand
temperature.
Studentsencounterincreasinglycomplexmodelsastheyproceedthroughthe
curriculumandshifttheirfocusfromthepartstothewhole.Theylearnthatthe
actualtemperatureincreaseonEarthisgreaterthanwhatwouldbeexpectedifonly
carbondioxidelevelswereconsidered.Thecurriculumintroducesnewvariables,
suchaswatervapor,intothemodelandasksstudentstoexplaintherelationships
amongtheinterrelatedpartsofthesystem.Studentscan,inthiscase,explorethe
effectoftwodifferentgreenhousegasesanddiscovertheinterrelationshipsamong
thelevelsofCO2,theamountofwatervaporintheatmosphere,andtheeffectson
atmospherictemperatures.
Feedback loops
Feedbackloopscanenhanceorbufferchangesthatoccurinasystem.Positive
feedbackamplifieschanges,andnegativefeedbacktendstodampenchanges
(ScienceEducationResourceCenteratCarletonCollege2003).Inclimatechange,
positivefeedbackacceleratestemperaturerise;negativefeedbackdeceleratesit.
TheModelingEarth’sClimatecurriculumexploresdifferentfeedbackloops.For
example,becauseiceisbothlightcoloredandreflective,sunlightthathitsice
bouncesbacktospace,limitingwarming.However,asEarthgetswarmer,icemelts,
revealingoceanorland,whicharedarkerthaniceandthereforeabsorbmoreofthe
sun’senergy.Thisleadstomorewarming,whichinturnleadstomoreicemelting,
andsooninthispositivefeedbackloop.Inthecurriculum,studentscanuseamodel
tochangethepercentoficecoveroramountofgreenhousegasesandcorrelate
thesechangestochangesinEarth’stemperature.
Anotherfeedbackloophighlightedinthecurriculumistheeffectsofcloudcoveron
Earth’stemperature.This,too,isabalancebetweensunlightreflectedoffcloudsand
awayfromEarth(acoolingeffect)andinfraredradiationfromEarthabsorbedby
cloudsandre‐radiatedintotheatmosphere(awarmingeffect).Inthemodel,
studentscanchangetheamountofcloudcoverandthenanalyzetheoutputgraph
(Figure2).(SeeKahn,p.xxofthisissue,formoreabouttheeffectofcloudson
climate.)Finally,thecurriculumalsomodelstherelationshipsamongCO2,
temperature,anddissolvedCO2intheoceans.Studentscanexplorewhathappensto
thelevelofCO2intheairandoceansasatmospherictemperaturechanges.Such
feedbackloopsarecomplexinthemselvesandareevenmorecomplexwhen
consideredaspartofanintegratedclimatesystem.
Climate models are complex
Ourbesthopeofunderstandinghowglobaltemperaturechangesovertime,and
howhumansmaybeaffectingit,liesintheclimatemodelsscientistshave
developed.Actualclimatemodelsaresomeofthemostcomplexmodelsinallfields
ofscience.Clearly,thecurriculummodelsaremuchsimpler,yettheyprovideuseful
toolstoteststudentideas,makepredictions,andunderstandsystemthinking.
ModelingEarth’sClimatescaffoldsstudentthinkingbyfocusingonhowthemodel
representspartsofthesystem,theinteractionswithinthesystem,andthemodel
limitations.Thecurriculumdoesthisbyaskingexplicitquestionsaroundmodels
suchas“Howdoesthelevelofcarbondioxideaffectthelevelofwatervaporinthe
atmosphere?”“Howcanyoutellthatamodelisgood?""Whatkindsoftestscanyou
runtoassessthevalidityofthemodel?”
AFrameworkofK‐12Education:Practices,CrosscuttingConcepts,andCoreIdeas
(NRC2012)statesthatmodelscanbevaluableforexploringasystem’sbehaviors.
Bysimulatingclimateinthepast,scientistscanseehowwellthemodelscompareto
real‐worlddataandjudgehowtheymightpredictthefuture.TheHigh‐Adventure
Sciencecurriculumalsohasstudentscomparemodeloutput—andtheirown
conclusions—toreal‐worlddata.
Asstudentsincreasethecomplexityofthemodels,theymovefromavaguesense
that“everythinginteracts”tomoreconcreteexamplesofthephysical,chemical,
biological,andhumaninteractionsrelatedtoclimatechangeoutcomesemerging
fromthemodel.Embeddedassessmentsaskstudentstodescribeexplicitlythe
behaviorofthesystemanditsmanyinteractingvariables,aswellasthecause‐and‐
effectrelationshipsinthesystem.Forexample,studentsmustreporthowchanges
intheamountoficecoveringEarth’ssurfacecanaffectEarth’stemperature.Student
responsestothisquestionincluded:“Themoreicecoverage,thecolderitwillget
becausethesun’sraysarereflectedbackoutoftheatmosphere,”and,“Whenthere
ismoreice,theicewillreflectalloftheenergyfromthesunandthereforetheEarth
willbealotlesswarm.”Thistypeofquestionmakesstudentsthinkaboutthe
interrelationshipsinthesystem.Askingstudentstoexplainthemechanismsof
complexfeedbackloopsalsorequireshigher‐orderthinkingaboutinterrelated
variables.
Wehaveanalyzedstudentpre‐andpost‐testworkfor260middleandhighschool
EarthScienceandEnvironmentalscienceclasses.Thetestincludeditemsthat
focusedoncontentandnatureofscienceskills,consistingofmultiplechoiceand
short‐answerquestions.Weconcludedthatstudentsofalllevelscanimprovetheir
systemsthinkingmodeledinourclimatechangecurriculum.Thetestcanbefound
ontheHigh‐Adventurewebsite(see"Ontheweb").
Human interactions and the climate system
Youcan’tstudyclimatechangethesedayswithoutlookingspecificallyat
anthropogeniccausesofchange.ClimateLiteracy,TheEssentialPrinciplesofClimate
Science(U.S.GlobalChangeResearchProgram2009)states:“Theoverwhelming
consensusofscientificstudiesonclimateindicatesthatmostobservedincreasein
globalaveragetemperaturessincethelatterpartofthe20thcenturyisverylikely
duetohumanactivities,primarilyfromincreasesingreenhousegasconcentrations
resultingfromburningoffossilfuels.”(p.6)Thisbringsusbacktoouroriginalsetof
questions:CanasingleautomobiledriveraffectEarth’sclimateandhowdowehelp
studentslearnabouttheroleofhumansinchangingclimate?TheHigh‐Adventure
Sciencecurriculumincludesopportunitiesforstudentstoexplorehowhuman‐
producedemissions(basedonburningfossilfuels)canchangeaverageEarth
temperaturesovertime.Studentstestwhathappenswhentheyincreasehuman‐
producedgreenhousegasemissionsandwhathappenswhentheyreducehuman‐
causedemissions.Thelevelofemissionsisonemorevariableinthecomplexsystem
thatismodeled.However,themodelaloneisnotenough;studentsmustalso
compareoutcomestoreal‐worlddata.Thecurriculumhasstudentsanalyzeclimate
changebasedonicecoredata(Figure3),oceanatmospheredata,andtheKeeling
curvegraphsofongoingatmosphericchangeinCO2concentration,amongothers.
Climatechangescienceiscomplex,andstudentsarenotexpectedtomasterevery
detailthroughthecurriculum.Butgreatercomprehensiondoesrequiresystems
thinking,namelytheabilitytounderstandhowvariouscomponentsinfluenceeach
otherwithinacomplexsystem,themodelsusedtorepresentthesesystems,andthe
interconnectionsamongthecomponentparts.
TheFrameworkincludesabroaderrangeofideasinEarthandSpacesciencethan
previousefforts.Coreideasincludefocuson1)Earth’sSystems,2)Earthandhuman
activity,and3)anunderstandingofscientificpractices.Prominentinallthreeof
thesecoreideasisclimatechangescience.TheFrameworkspecifiesthatstudents
shouldlookatfeedbackloops,exploreinterconnectedfeaturesofEarth’sclimate
system,comparehistoricandpresentclimatechange,aswellasstudythewaysin
whichhumanactivitiesrelatetoEarth’sprocesses.TheModelingEarth’sClimate
curriculumstronglyintegratesthesecoreconcepts.(NationalResearchCouncil,
2012,p196‐198).
Conclusion
Howweexamineproblemsdependsinpartonourworldview.Withanysystemthe
wholeisdifferentthanthesumofitsparts.TheHigh‐AdventureScienceModeling
Earth’sClimatecurriculumengagesstudentsinsystemsthinking,enablingthemto
constructtheirownknowledgeonfactorsthatinfluenceclimatechange,compareit
todatafromthescientificcommunity,andthinkcriticallyaboutcomplexitiesof
climatechange.
AmyPallant([email protected])istheprincipalinvestigatorontheHigh‐
AdventureScienceproject,andSaraPryputniewicz([email protected])is
aresearchassistant,bothattheConcordConsortiuminConcord,Massachusetts;Hee‐
SunLee([email protected])isavisitingassistantprofessorattheUniversity
ofCalifornia,SantaCruz.
Acknowledgements
TheauthorthanksDr.R.Tinkerforhisworkondevelopingthemodelsinthe
curriculum.ThisworkissupportedbytheNationalScienceFoundation(NSF)under
grantDRL‐0929774.Anyopinions,findings,andconclusionsorrecommendations
expressedinthispaper,however,arethoseoftheauthorsanddonotnecessarily
reflecttheviewsoftheNSF.
On the web
ConcordConsortium:www.concord.org/projects/high‐adventure‐science
NetLogo:http://ccl.northwestern.edu/netlogo/
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%20Hi‐Res.pdf
Figure1:ClimateModel.Thismodelallowsstudentstofollowenergy(representedby
yellowarrows)fromthesunastheyinteractwithgreenhousegases(representedby
greendots0andtheEarth’ssurfacewheretheyarereflectedasinfraredradiation
(representedbyredarrows)orabsorbedasheat.Studentscanchangetheamountof
CO2intheatmosphereAsstudentsincreasetheC02thetemperatureincreasesasseen
inthegraph.
Figure2:Thismodelallowsstudenttochangethecloudcovertoseehowanincrease
inclouds,inthiscase,lowerstemperature.Studentsobservetherelationshipbetween
cloud‐cover,incomingsolarradiation(yellowarrows),infraredradiations(red
arrows)greenhousegases(blueandgreendots)andland,oceanandicetohelp
explaintheresultinggraph.
Figure3.Atmosphericcarbondioxideconcentrationduringthepast417,000years.
http://upload.wikimedia.org/wikipedia/commons/8/88/CO2‐417k.png