Chapter 3: How to Think About Complex Systems PDF

Chapter 3: How to Think About Complex Systems Systems – A system is a set of components or parts that function together to act as a whole. E.g. Body, city, river Open system- some energy or material moves into or out of system. Fi Closed system- no such movements take place. water cycle Stability –...

Chapter 3: How to Think About Complex Systems Systems – A system is a set of components or parts that function together to act as a whole. E.g. Body, city, river Open system- some energy or material moves into or out of system. Fi Closed system- no such movements take place. water cycle Stability – – A stable system is one that Has a condition that it remains in unless disturbed. Condition that it returns to if disturbed from it and the cause of the disturbance stops. Whether this is desirable depends on the system and potential changes. Environmental Unity – med Everything affects everything else It is impossible to change only one thing Earth and its O ecosystems are O complex entities in which any action may have several or many effects. Environmental Unity: An Urban O Example Many mid-western US cities (i.e. Chicago) have 0 had a shift in land use – Forest or agricultural land to urban development – an Construction increases runoff and soil erosion Affects river channels and flood hazard After construction sediment load decreases but runoff still increases Thus land-use changes set off a series of changes which can trigger additional changes. 0 Uniformitarianism The physical and biological processes presently forming and modifying Earth are the same now as they were in the past. PRESENT is the KEY to the PAST A study of past and present processes is KEY to the FUTURE. Changes and Equilibrium in Systems EOE 0 – – Earth and Life Earth formed 4.7 billion years ago Life began on Earth 3.5 billion years ago Eda Since life’s emergence many organisms have evolved, flourished, and become extinct. Humans may one day become extinct. Human activities increase and decrease the magnitude and frequency of natural processes, leading to many human caused extinctions. Numerous species have been wiped out primarily by human hunters in the last couple hundred years alone. there is a list of 13 animals that have been hunted to extinction. (Text: Bryan Nelson) The last known wild Tasmanian I tiger was killed by O a farmer named Wilf Batty, who O shot the animal after it had been sighted patrolling outside of his house. Earth as a Living System o – – – Biota- all living things within a given area Biosphereregion of Earth where life exists o Also includes the system that sustains life All living things require energy and materials. Energy from the sun and interior of Earth Materials recycles through the system o Ecosystem – – – a o A community of organisms and its local nonliving environment in which matter cycles and energy flows. Can be applied to different scales Puddle to forest to planet What is common to all is not physical structure (cell to organ to body.. ), but existence of processes (Nutrition, respiration……..) Can be natural or artificial – – – – – Why Solving Envt. Problems Is Often Difficult? 1. Exponential growth Dramatic consequences, leading to incredible increases. 2. Lag time The time between a stimulus and the response of a system. Long lag time or delays may lead to overshot and collapse Going beyond the carrying capacity can lead to a collapse of a population. 3. Irreversible consequences Consequences that may not be easily rectified on a human scale of decades or a few hundred years. to so