1. Welcome! Pick up your journal from the table. Pick up Chapter 3 reading questions (next to journals) Place timeline on table next to journals. Check on your seeds. Set up a data table in your notebook (remember to title it!) and record any data. We will be collecting data for 3 days. Consider using both count and measurement data. Check board for HW and write down in planner.

2. Systems of Change

3. 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. Closed system- no such movements take place.

4. Environmental Unity It is impossible to change only one thing –Everything effects everything else Earth and its ecosystems are complex entities in which any action may have several or many effects.

6. Environmental Unity: An Urban Example Many midwestern US cities (i.e. Chicago) have had a shift in land use –Forest or ag land to urban development Construction increases runoff and soil erosion –Effects 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.

8. Environmental Unity: A Forest Example Forest, stream and fish in the Pacific Northwest Wood debris form and maintain pool environments in small stream. –Provide rearing habitat for young salmon –Formerly removed because thought to block fish migration Studying relations between physical and biological systems at the heart of environmental science

9. Feedback Loops A feedback loop occurs when an output of a system is fed back as an input Two kinds of feedback loops –Positive –Negative

10. Feedback Positive feedback- an increase in output leads to a further increase in the output. –Destabilizing Environmental damage can be especially serious when people’s use of the environment leads to positive feedback.

11. Positive Feedback

13. Positive feedback loop Exponential growth of population – more individuals lead to increased number of births

14. Negative feedback loop Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating

15. Feedback Some situations involve both + and – feedback. Human pop in large cities.

16. 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.

18. Complex systems Time lags – change in a system leads to other changes after a delay – lung cancer Resistance to change – built in resistance – political, economic Synergy-when two or more processes interact so that the combined effect is greater Chaos – unpredictable behavior in a system

19. Synergy and Chaos Synergy occurs when two or more processes interact so the combined effect is greater than the sum of the separate effects –Grapefruit and Statins Chaos occurs in a system when there is no pattern and it never repeats itself –Noise versus Music

20. Gaia hypothesis The hypothesis states that life manipulates the environment for the maintenance of life. –Planet capable of physiological self-regulation Really a series of hypotheses –Life has greatly affected the planetary environment –Life has altered Earth’s enviro in ways that have allowed it to persist

21. Why Solving Environmental Problems Is Often Difficult 1. Exponential growth –The consequences of EG and its positive feedback can be dramatic, leading to incredible increases of what is being evaluated or measured.

22. Why Solving Environmental Problems Is Often Difficult 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 carry capacity can lead to a collapse of a population.

24. Why Solving Environmental Problems Is Often Difficult 3. Irreversible consequences –Consequences that may not be easily rectified on a human scale of decades or a few hundred years.