Botkin & Keller Environmental Science 5/e Chapter 3 The Big Picture: Systems of Change

SYSTEM System: –A set of components or parts that function together to act as a whole. Botkin & Keller Environmental Science 5/e

Botkin & Keller Environmental Science 5/e Systems –Example: Solar System –What are other examples of systems?

Different types of systems Open –Examples: Closed –Examples Botkin & Keller Environmental Science 5/e

Systems Respond to Inputs and OUtputs Example: –Input ---- the sight of a bear Reaction – heart rate increases, adrenaline increases –Output --- Slowly move away The ‘Response’ is called FEEDBACK FEEDBACK leads to further changes in the system. THINK OF YOUR OWN EXAMPLE Botkin & Keller Environmental Science 5/e

Botkin & Keller Environmental Science 5/e Systems and Feedback Feedback –Occurs when the output of the system also serves as an input, leading to further changes in the system Negative Feedback –Self-regulating –stabilizing Positive Feedback –Occurs when an increase in output leads to a further increase in output –Destabilizing usually causes env. damage

Vicious Cycle Copy this Chart into Your notes Botkin & Keller Environmental Science 5/e © 2008 John Wiley and Sons Publishers

Botkin & Keller Environmental Science 5/e © 2008 John Wiley and Sons Publishers

Botkin & Keller Environmental Science 5/e Environmental Unity Environmental unity: FUNDAMENTAL CONCEPT IN ENV.SCI. –It is impossible to change only one thing; everything affects everything else. –This is ALWAYS true: Changes in one part of a system often have secondary and tertiary effects within the system or adjacent systems. Read Chapter 3 Case study page 39: write a paragraph explaining how the Amboseli National Reserve is an example of “environmental unity”

Botkin & Keller Environmental Science 5/e Uniformitarianism Uniformitarianism: –The principle and processes that operate today operated in the past. –Observations of processes today can explain events that occurred in the past and leave evidence “The present is the key to the past.”

Botkin & Keller Environmental Science 5/e Changes and Equilibrium in Systems Steady state: –A dynamic equilibrium – “input = output” –Material or energy is entering and leaving the system in equal amounts –Opposing processes occur at equal rates –Ex: incoming solar energy = outgoing energy from the Earth SYSTEMS RARELY MAINTAIN EQUILIBRIUM. HUMAN & NATURALY DISTURBANCES ARE ALWAYS AFFECTING THE BALANCE

Botkin & Keller Environmental Science 5/e © 2008 John Wiley and Sons Publishers

Botkin & Keller Environmental Science 5/e Changes and Equilibrium in Systems Average residence time: –The time it takes for a given part of the total reservoir of a particular material to be cycled through the sytem –The equation for average residence time is: ART = S/F

Botkin & Keller Environmental Science 5/e © 2008 John Wiley and Sons Publishers

Botkin & Keller Environmental Science 5/e Why Solving Environmental Problems Is Often Difficult 1.Exponential growth The consequences of exponential growth and its accompanying positive feedback can be dramatic 2.Lag time The time between a stimulus and the response of a system If there is a long delay between stimulus and response, then the resulting changes are much more difficult to recognize. 3.Irreversible consequences Consequences that may not be easily rectified on a human scale of decades or a few hundred years.

Growth factors Botkin & Keller Environmental Science 5/e

Botkin & Keller Environmental Science 5/e © 2008 John Wiley and Sons Publishers

Botkin & Keller Environmental Science 5/e The Gaia Hypothesis: –Named for Gaia, the Greek goddess Mother Earth –States that the surface environment of the Earth, with respect to such factors as the atmospheric composition of gases acidity-alkalinity of waters Surface temperature are actively regulated by the sensing, growth, metabolism and other activities of the biota. –Or, life manipulates life the environment for the maintenance of life.