Dave Bice Dept of Geosciences Penn State University What do I mean by complexity Systems whose behavior is nonlinear and thus difficult to predict M ultiple stable states Hysteresis behavior ID: 1025699
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1. Modeling as a Way of Learning About Complexity in Earth SystemsDave BiceDept. of GeosciencesPenn State University
2. What do I mean by complexity?Systems whose behavior is non-linear and thus difficult to predict.Multiple stable states Hysteresis behaviorStrong sensitivity to initial conditionsChaotic (non-periodic) oscillations Why should we care about complex systems?Our climate system is a complex systemWhat are the barriers to teaching and learning about complex systems?Need to first understand the dynamics of simple systems & feedbacksNeed to be able to construct and then experiment with systems to see how they workGreenhouse ForcingGlobal TemperatureHysteresis and Snowball Earth
3. Learning about Complexity with STELLA modelsThe Modeling ProcessDefinition of conceptual model of relevant systemTranslation of conceptual model into model diagramAdding numbers and equations to express the processesTesting model, comparing with known behavior of the real world systemExperimenting with model — iteration between question asking, prediction, running the model, analysis of data, more questions, etc.Starts with observations of interesting real world dynamicsWriting and talking about results and their implications for the real world system.
4. Greenland Ice Core Record back to 50 kyrOxygen isotope ratio of Greenland IceTime (kyr BP)Younger Dryas EventStarts with observations of interesting real world dynamics
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7. del T = Te-Tp del S = Se-SpDefinition of conceptual model of relevant system
8. Translation of conceptual model into model diagramAdding numbers and equations to express the processes and initial conditionsdel T = Te-Tp del S = Se-Sp
9. Sensitivity to initial conditions and 2 stable statesExperimenting with model — iteration between question asking, prediction, running the model, analysis of data, more questions, etc.5 simulations with small changes in the starting delS value
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11. A topographic analogy for the stable states seems to help some of the students think about the this system
12. Simulating the Younger Dryas…Steady state with vigorous mixing, warm polar regionSteady state with weak mixing, cold polar regionA brief pulse of freshwater into the northern Atlantic pushes the system into the other steady state
13. So… does it work? I think so, and at the very least, they have a model to help guide their thinking and questioning about the system that has given us this record. Greenland Ice Core RecordOxygen isotope ratio of Greenland IceTime (kyr BP)Younger Dryas Event