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UCSB ENVS 106 - Lecture 12 Thinking in Systems Chatper 6_POST

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Slide 1Chapter 6: Leverage Points— Places to Intervene in a SystemLeverageChapter 6: Leverage Points – Places to Intervene in a SystemMIT’s Jay ForresterSlide 6Numbers (Rank 12) – Constants and ParametersIntervention (Rank 11): BuffersStock and Flow Structures (Rank 10)Slide 10Slide 11Slide 12Intervention (Rank 9): DelaysSlide 14Intervention (Rank 8): Balancing Feedback LoopsSlide 16Slide 17Examples of Balancing Feedback SuccessIntervention (Rank 7): Reinforcing Feedback LoopsSlide 20Intervention (Rank 6): Information FlowsRules (Rank 5) – Incentives, Punishments, ConstraintsSlide 23Self-Organization (Rank 4)Intervention (Rank 3): GoalsInterventions (Ranks 1 & 2): PARADIGMSSlide 27Interventions (Ranks 1 & 2): PARADIGMSExtra Credit OpportunityMark your Calendars!For more than three decades and in more than a dozen books, Professor Robert D. Bullard has documented that healthy places and healthy people are highly correlated. The poorest of the poor within the United States have the worst health and live in the most degraded environments. Bullard’s lecture explores how the environment justice framework redefined environmentalism and challenged institutional racism and the dominant environmental protection paradigm.Chapter 6: Leverage Points—Places to Intervene in a SystemLeverage•The silver bullet•The miracle cure•The secret passage•The magic password•The Easy ButtonChapter 6: Leverage Points – Places to Intervene in a System •Leverage•Interventions to improve system performance may often be counterintuitiveEconomic growth may not be good for poverty and hunger or unemployment, or resource depletionSubsidized housing has unintended feedbacksEnsure people have jobs and housing manages itself•(not without controversy)•Surprising system behaviors can result from “common sense” policies and system interventions!MIT’s Jay ForresterForrester (1971) Counterintuitive Behavior of Social SystemsIn fact, it emerges that the fundamental cause of depressed areas in the cities comes from excess housing in the low-income category rather than the commonly presumed housing shortage. The legal and tax structures have combined to give incentives for keeping old buildings in place. As industrial buildings age, the employment opportunities decline. As residential buildings age, they are used by lower-income groups who are forced to use them at a higher population density. Therefore, jobs decline and population rises while buildings age. Housing, at the higher population densities, accommodates more low-income urban population than can find jobs. A social trap is created where excess low-cost housing beckons low-income people inward because of the available housing. They continue coming to the city until their numbers so far exceed the available income opportunities that the standard of living declines far enough to stop further inflow. Income to the area is then too low to maintain all of the housing. Excess housing falls into disrepair and is abandoned.Counterintuitive—that’s Forrester’s word to describe complex systems. Leverage points frequently are not intuitive. Or if they are, we too often use them backward, systematically worsening whatever problems we are trying to solve…I offer this list to you with much humility and wanting to leave room for its evolution. What bubbled up in me that day was distilled from decades of rigorous analysis of many different kinds of systems done by many smart people. But complex systems are, well, complex. It’s dangerous to generalize about them. What you read here is still a work in progress; it’s not a recipe for finding leverage points. Rather, it’s an invitation to think more broadly about system change.Numbers (Rank 12) – Constants and Parameters •E.g., subsidies, taxes, standards•Changing the inflows or outflows usually has only a small effect on the stock, especially in the short term•Larger changes in the flows usually mean much larger changes in the system as a wholeNational DebtExpenditures TaxesThis system layout may be somewhat counterintuitive, but it should make sense after processing it carefullyIntervention (Rank 11): Buffers•Think of the bathtubSlow inflows and outflows, high stockFast inflows and outflows, low stock•Buffers can add some resilience to a systemChecking AccountInventory Endangered Species Population (higher than minimum breeding)There’s leverage, sometimes magical, in changing the size of buffers. But buffers are usually physical entities, not easy to change. The acid absorption capacity of eastern soils is not a leverage point for alleviating acid rain damage. The storage capacity of a dam is literally cast in concrete. So I haven’t put buffers very high on the list of leverage points.Lake!River!Stock and Flow Structures (Rank 10)•Lay out the physical and social systems with forethought!•Baby boom stress pointsElementary schoolsHigh SchoolsCollege Jobs/HousingRetirementPhysical structure is crucial in a system, but is rarely a leverage point, because changing it is rarely quick or simple. The leverage point is in proper design in the first place. After the structure is built, the leverage is in understanding its limitations and bottlenecks, using it with maximum efficiency, and refraining from fluctuations or expansions that strain its capacity.Pump 1Backup Pump 2What’s wrong with this system?Here you have symmetrical elegance in the design, but each bend and curve represents inefficiencies because of the feedbacks that occur with fluids changing direction rapidly.Backup Pump 2Pump 1An improved design – you minimize curves for the main pump that operates 95% of the time, reducing the inefficiency of the curve to only 5% of the time, and not with and abrupt curve spot, but a diagonal intersection.For physical systems that have to be planned and laid out, minimizing feedbacks is key!VideoYou are in a circle of cars spaced about 30 feet apart each. You are told to drive at a consistent 20 mph. What do you think will happen?A. I can keep going at 20 mph, no problem. The system will work fine!B. Some goofball in front of me will screw it upC. The nature of the system will place limitations on everyone’s ability to do soNo matter how good of a driver you may think you are (and yes, you all are good drivers I’m sure ) when densities of cars on a roadway system get large enough, feedbacks from even the slightest


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