UCSB ENVS 106 - Lecture 12 Thinking in Systems Chatper 6_POST (28 pages)

Previewing pages 1, 2, 3, 26, 27, 28 of 28 page document View the full content.
View Full Document

Lecture 12 Thinking in Systems Chatper 6_POST



Previewing pages 1, 2, 3, 26, 27, 28 of actual document.

View the full content.
View Full Document
Unformatted text preview:

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 Extra Credit Opportunit y Mark your Calendars Chapter 6 Leverage Points Places to Intervene in a System Leverage The silver bullet The miracle cure The secret passage The magic password The Easy Button Chapter 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 Forrester Forrester 1971 Counterintuitive Behavior of Social Systems In fact it emerges that the fundamental cause of depressed areas in the cities comes from excess housing in the lowincome 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 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 whole Expenditures National Debt This system layout may be somewhat counterintuitive but it should make sense after processing it carefully Taxes Intervention Rank 11 Buffers Lake Think of the bathtub Slow inflows and outflows high stock Fast inflows and outflows low stock River 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 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 Retirement Physical 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 What s wrong with this system Pump 1 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 2 An 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 Pump 1 Backup Pump 2 You 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 up C The nature of the system will place limitations on everyone s ability to do so No 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 perturbation the result of perception and reaction delays cause oscillation patterns that simply cannot be attributed completely to individual cars but must Video be thought of as a systems phenomenon This is directly related to the carrying capacity and actual occupancy of the roadway in question It gets even worse when you have multiple lanes entry and exit points and of course goofball that https www youtube com watch v 7wm pZp mi0 Intervention Rank 9 Delays Would be a high leverage point But not easily changeable Construction of major capital Maturation of children Growth rates of trees Easier to slow down the change rate A delay in a feedback process is critical relative to rates of change in the stocks that the feedback loop is trying to control Delays that are too short cause overreaction chasing your tail oscillations amplified by the jumpiness of the response Delays that are too long cause damped sustained or exploding oscillations depending on how much too long Overlong delays in a system with a threshold a danger point a range past which irreversible damage can occur cause overshoot


View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view Lecture 12 Thinking in Systems Chatper 6_POST and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture 12 Thinking in Systems Chatper 6_POST and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?