Systems Science and Sustainability (Physical Systems)

1. Systems Science and Sustainability(Physical Systems) Oct. 13, 2008 Jeff Fletcher

2. Plan • Discuss Systems and Systems Science • Identify Key Systems Ideas • Use examples from Earth Systems • Focus today on natural physical systems rather than social systems • Other systems ideas are more relevant to social systems (later terms)

3. Justification • Sustainability involves complex and interrelated issues • e.g., Climate change involves multiple complex systems (both natural and social) • e.g., Population control involves multiple complex systems (both natural and social) • So what do we know about systems that might give us a framework for more effectively addressing Sustainability?

4. What is a System? • Consider an ecosystem and economic system: what is similar? Why are they both called systems? • Why might it be useful to focus on their similar “system-ness” rather than on their uniqueness?

5. Systems • Comprised of: • Elements • Ecosystem and Economic system examples? • Interactions or relations • Ecosystem and Economic system examples? • A common relation between systems is hierarchical • subsystems, supra-systems • Consider some earth systems • Other ideas • order vs. disorder, order is constraint on relations • relations describe structure vs. total disorder (entropy) • system and environment • boundaries define systems

6. What is Systems Science? • Consider flocking birds, schooling fish, a group of friends walking together • ornithologist, ichthyologist, sociologist • Mario Bunge “Stuff-free science” • How is knowledge normally grouped at a University? • System Science not as abstract as math and philosophy • But more abstract (general) than individual disciplines • Systems Science emphasizes theories that cut across disciplines • Game Theory, Evolution Theory, Information Theory, Network Theory, Chaos Theory, Complexity Theory, etc • Interested in addressing real-world, complicated problems, from a multidisciplinary perspective

7. Key Ideas About Systems • What makes a system? • Elements and Relations • order vs. disorder • system vs. environment • Systems States and Dynamics • Equilibria, Stability • Positive and Negative Feedbacks • Non-linear dynamics • Chaos Theory, Catastrophe Theory • Emergence • Structure • Open vs. Closed • Matter, Energy, Information

8. Systems can be in different states • For instance, temperature or composition of atmospheric system • How systems change states over time is called dynamics • Equilibria • Stable vs. Unstable • Static vs. Dynamic • Example of day length at equator vs. day length elsewhere • Positive and Negative Feedbacks (aphids) • Exponential growth example of + feedback • Homeostasis example of - feedback

9. Complex Systems Yield Surprises • Most models of systems are linear • Change in state predicted to be proportional to change in inputs • Most real and complex systems are non-linear • Systems with feedback are often unpredictable • Small causes can have big effects • Butterfly effect from Chaos theory • Catastrophe theory: state is not reversible by reversing cause • Current financial crisis is great example • Emergence

10. Examples from Atmosphere • Is CO2 effect proportional to its abundance in atmosphere? • What proportion is CO2? • Caution in reading graphs • What is ppm in percent? • nitrogen (78%), oxygen (21%) and argon (.93%) = 99.93% of atmosphere! • Methane also has disproportionate effects • Ozone hole: example of unintended consequences and irreversibility (video) • Big hole until 2017, then hole will start to shrink; back to 1980 level in year 2070! • Example of not reversible, directionality

11. Water Vapor in Atmosphere • Also a small proportion of atmosphere • Effect is being debated: • What would be example of positive feedback with water vapor and global warming? • What would be example of negative feedback?

12. Earth Relatively Closed System to Matter • We don’t get any more atoms here on earth • We keep reusing the Hydrogen, Nitrogen, Oxygen, and Carbon atoms we have • Nature’s Recycling • Structure of these systems varies • N critical to proteins in living organisms and abundant in atmosphere, but mostly unavailable • Depends on symbiotic relationship in plants with bacteria that “fix” nitrogen • O part of H20, C02, Carbohydrates (systems interconnected) • Bodies burn carbohydrates -- Cn(H20)n • (e.g. glucose C6H12O6 + 6O2 <=> 6CO2 + 6H20 + Energy) • Plants can do this backwards with sun for E! • Similar to burning hydrocarbons (only C + H, i.e. methane=natural gas) CH4 + 202 = CO2 + 2H20 + energy • C lots of it, but relatively little of it is cycling in atmosphere • Most of the carbon is stored in geologic deposits - carbonate rocks, petroleum, and coal - formed from the burial and compaction of dead organic matter on sea bottoms. The carbon in these deposits is normally released by rock weathering. • Extraction and burning of fossil fuels alters this system

13. Atmosphere is Relatively Flat Systems (not much hierarchy) • Air molecules are very small compared to space between them • Can treat them as all the same (Ideal Gas Assumption) • A Linear relationship holds (roughly) for earth’s atmospheric temperatures and pressures • PV = nRT • Caesar’s Last Breath

14. Energy and Heat • Earth is an open system to Energy • ability to do work • Potential, Kinetic, Heat Energy • Heat: Radiation • electromagnetic waves (even through vacuum) • Sunlight, microwaves, infrared • Heat: Conduction • molecular vibrations in solids spreads to neighbors • Heat: Convection • Molecules move in gases and liquids—collide and spread their kinetic energy

15. Entropy • Second Law of Thermodynamics: • entropy (disorder) increases (or at best stays the same when cycles of work are done (for closed systems) • Order necessary to maintain system’s integrity • comes from energy flow into system (not closed), e.g. sunlight on earth • Overall Entropy is increasing in the Universe, but there are “back eddies” of order driven by energy input (e.g. life on earth)

16. Matter, Energy, Information • Matter can be seen as acted upon by energy • But understanding matter and energy relationship is not enough • Information can organize matter and energy • Acorn Example

17. More Socially Relevant Systems Ideas • Optimization • Local vs. global • Cannot optimize system and its subsystems at the same time • Tension between systems and subsystems • Examples • You and your liver • Efficient country and local autonomy/control • Game Theory • Tragedy of the Commons • Prisoner’s Dilemma, Chicken • Discounting Future • Maximin, Nash Equilibrium, Pareto Optimality

18. Summary • Another way to think about systems: • Complex systems have inherent problems that are affected by their systems characteristics • Characteristics worth thinking about include: • Dynamics (equilibria, +/- feedbacks, non-linearity, emergence) • Structure of relationships • Open vs closed (matter, energy, entrpy) • Degree of hierarchy • Hierarchy of Matter, energy, information