1. Chapter Four systems: a theoretical framework

2. The Biosphere … the biosphere includes air, rocks, water and life Atmosphere : a mixture of nitrogen (78%), oxygen (21%), and carbon dioxide (1%) Atmosphere : a mixture of nitrogen (78%), oxygen (21%), and carbon dioxide (1%) Hydrosphere: the water on Earth in all its states and the elements dissolved in it Hydrosphere: the water on Earth in all its states and the elements dissolved in it Lithosphere: the thin crust between the mantle and the atmosphere (rocks) Lithosphere: the thin crust between the mantle and the atmosphere (rocks) Ecosphere: made up of all living organisms; temporary accumulators and sources of pollutants Ecosphere: made up of all living organisms; temporary accumulators and sources of pollutants

3. Types of Systems: Open System: exchanges matter and energy with its surroundings Open System: exchanges matter and energy with its surroundings Closed System: exchanges energy but not matter with its environment Closed System: exchanges energy but not matter with its environment Isolated System: exchanges neither matter nor energy with its environment Isolated System: exchanges neither matter nor energy with its environment

4. Closed System: Closed systems are very rare on earth; the earth itself can be almost considered a closed system Closed systems are very rare on earth; the earth itself can be almost considered a closed system

5. Open System: Most systems are open systems; all ecosystems are open Most systems are open systems; all ecosystems are open

6. Isolated System Isolated systems do not exist naturally, yet it is possible to picture the entire universe as an isolated system Isolated systems do not exist naturally, yet it is possible to picture the entire universe as an isolated system

7. Laws of Thermodynamics First Law: First Law: – “energy is neither created nor destroyed” Second Law: Second Law: – “the entropy of an isolated system not in equilibrium will tend to increase over time” Energy conversions are never 100% efficient Energy conversions are never 100% efficient Entropy: the spreading out or dispersal of energy

8. Equilibrium: Steady-State Equilibrium: a characteristic of open systems where there are continuous inputs and outputs of energy and matter, but the system as a whole remains more-or-less constant Steady-State Equilibrium: a characteristic of open systems where there are continuous inputs and outputs of energy and matter, but the system as a whole remains more-or-less constant Static Equilibrium: there is no change over time; when disturbed, it will adopt a new equilibrium Static Equilibrium: there is no change over time; when disturbed, it will adopt a new equilibrium *** Systems can also be stable or unstable

9. Feedback Positive Feedback Positive Feedback – When students respond positively to teaching methods through learning and showing interest Negative Feedback  Negative Feedback  – When students respond negatively to teaching methods through distraction, indifference or dissent

10. Positive Feedback in Global Warming Higher Temperature More Water Vapor More Heat Trapped By Atmosphere Wetter Atmosphere Land and Sea Temperatures Rise Increased Evaporation

11. Transfers and Transformations Transfer: Occurs when the flow does not involve a change of form or state Transfer: Occurs when the flow does not involve a change of form or state Transformation: Occurs when a flow does involve a change of form or state Transformation: Occurs when a flow does involve a change of form or state

12. Transfers and Transformations TransfersTransformations Movement of material through living organisms Matter to matter Movement of material in a non-living process Energy to energy Movement of energy Energy to matter

13. Flows and Storages “Both energy and matter flow (as inputs and outputs) through ecosystems but, at times, they are also stored (as storage or stock) within the ecosystem” When one organism eats another, the energy is flowed between them as stored chemical energy When one organism eats another, the energy is flowed between them as stored chemical energy Energy flows through a system in the form of carbon- carbon bonds within organic compounds Energy flows through a system in the form of carbon- carbon bonds within organic compounds Matter cycles around the system as minerals Matter cycles around the system as minerals

14. General Flows in An Ecosystem Atmosphere Nutrient elements in soil and water Elements combines in plant tissue Rock cycle Elements locked in sinks Elements combined in animal tissue Sedimentation and Fossilization Weathering Respiration Volatile Gases Feeding Absorbed Death and Decomposition

15. Energy Flow and Flow of Matter Through an Ecosystem Producers Inorganic Nutrient Pool Decomposers Consumers heat SUN

16. Complexity and Stability Most ecosystems are very complex systems that include feedback links, flows, and storages Most ecosystems are very complex systems that include feedback links, flows, and storages Primarily, a high level of complexity makes for a more efficient and stable system Primarily, a high level of complexity makes for a more efficient and stable system – i.e. tundra ecosystems are quite simple therefore populations within this ecosystem tend to fluctuate such as the lemming population (unstable)

17. Models of Systems “Simplified models of systems can help predict changes in the system by modeling reality...” A model can take many forms: A physical model (i.e. an aquarium) A physical model (i.e. an aquarium) A software model (i.e. of climate change) A software model (i.e. of climate change) Mathematical equations Mathematical equations Data flow diagrams Data flow diagrams

18. Gaia Alfred Russel Wallace described the atmosphere as the “Great Aerial Ocean” Alfred Russel Wallace described the atmosphere as the “Great Aerial Ocean” In 1979, James Lovelock published his “Gaia hypothesis” in Gaia: A new look of life on Earth In 1979, James Lovelock published his “Gaia hypothesis” in Gaia: A new look of life on Earth – Argued that “the Earth is a planet-sized organism and the atmosphere is its organ that regulates it and connects all its parts” – Argued that “the biosphere keeps the composition of the atmosphere within certain boundaries by negative feedback mechanisms”

19. Lovelock’s Argument Was Based On… 1. The temperature of the Earth’s surface is constant even though the sun is giving out 30% more energy than when the Earth was formed 2. The composition of the atmosphere is constant with 79% nitrogen, 21% oxygen, & 0.03% carbon dioxide. Oxygen is a reactive gas, but its proportion does not change 3. The oceans’ salinity is constant at about 3.4% but rivers washing salts into the sea might be expected to increase this

20. Lovelock’s Work Although many people rejected his hypothesis Lovelock defended it for 30 years with the support of Lynn Margulis Although many people rejected his hypothesis Lovelock defended it for 30 years with the support of Lynn Margulis He developed “Daisyworld” as a mathematical simulation that depicted how feedback mechanisms can evolve from activities of self- interested organisms He developed “Daisyworld” as a mathematical simulation that depicted how feedback mechanisms can evolve from activities of self- interested organisms James Lovelock

21. In 2006, Lovelock wrote The Revenge of Gaia, in which he argues that Earth is an “older woman”, more than half-way through her existence as a planet and not as able to bounce back like before In 2006, Lovelock wrote The Revenge of Gaia, in which he argues that Earth is an “older woman”, more than half-way through her existence as a planet and not as able to bounce back like before He says that we will be entering a stage of positive feedback where the stable equilibrium will become unstable and thus result in the shift to a new and hotter equilibrium state He says that we will be entering a stage of positive feedback where the stable equilibrium will become unstable and thus result in the shift to a new and hotter equilibrium state – “The human population will survive but with a 90% reduction in numbers”

22. The End!