Models and the behavior of systems IB syllabus: 1.1.1– Videos – The Story of Stuff Ch. 3

Syllabus Statements 1.1.1: Outline the concept and characteristics of a system 1.1.1: Outline the concept and characteristics of a system 1.1.2: Apply the systems concept on a range of scales 1.1.2: Apply the systems concept on a range of scales 1.1.3: Define the terms open system, closed system, isolated system 1.1.3: Define the terms open system, closed system, isolated system 1.1.4: Describe how the first and second laws of thermodynamics are relevant to environmental systems 1.1.4: Describe how the first and second laws of thermodynamics are relevant to environmental systems 1.1.5: Explain the nature of equilibria 1.1.5: Explain the nature of equilibria

Syllabus Statements 1.1.6: Define and explain the principles of positive and negative feedback 1.1.6: Define and explain the principles of positive and negative feedback 1.1.7: Describe transfer and transformation processes 1.1.7: Describe transfer and transformation processes 1.1.8: Distinguish between flows (inputs and outputs), and storages (stock) in relation to systems : Distinguish between flows (inputs and outputs), and storages (stock) in relation to systems : construct and analyze quantitative models involving flows and storages in a system 1.1.9: construct and analyze quantitative models involving flows and storages in a system Evaluate the Strengths and limitations of models Evaluate the Strengths and limitations of models

Vocab Entropy Entropy Equilibrium Equilibrium Feedback Feedback Negative Feedback Negative Feedback Positive Feedback Positive Feedback Model Model Stable Equilibrium Stable Equilibrium Steady State Equilibrium Steady State Equilibrium System Closed System Isolated System Open system

Systems A system is a set of components that… A system is a set of components that… 1. Function and interact in some regular, predictable manner. 2. Can be isolated for the purposes of observation and study.

Systems on Many Scales Ecosystem – The everglades in South FL Ecosystem – The everglades in South FL Biome – Tropical Rainforest Biome – Tropical Rainforest The entire planet – Gaia hypothesis The entire planet – Gaia hypothesis

Coral Reef Ecosystem Most diverse aquatic ecosystem in the world Open systems exchange matter and energy with the surroundings

Closed systems exchange energy but not matter. – don’t naturally occur on earth Biosphere II Biosphere II Built as self sustaining closed system in 1991 in Tuscon, AZ Experiment failed when nutrient cycling broke down

Nutrient cycles Approximate closed systems as well

Isolated systems exchange neither matter nor energy with the surroundings Only possible though unproven example is the entire cosmos

Components of systems Inputs = things entering the system  matter, energy, information Inputs = things entering the system  matter, energy, information Flows / throughputs = passage of elements within the system at certain rates (transfers and transformations) Flows / throughputs = passage of elements within the system at certain rates (transfers and transformations) Stores / storage areas = within a system, where matter, energy, information can accumulate for a length of time (stocks) Stores / storage areas = within a system, where matter, energy, information can accumulate for a length of time (stocks) Outputs = flowing out of the system into sinks in the environment Outputs = flowing out of the system into sinks in the environment

Discharge of untreated municipal sewage (nitrates and phosphates) Nitrogen compounds produced by cars and factories Discharge of treated municipal sewage (primary and secondary treatment: nitrates and phosphates) Discharge of detergents ( phosphates) Manure runoff from feedlots (nitrates, phosphates, ammonia) Dissolving of nitrogen oxides (from internal combustion engines and furnaces) Runoff and erosion (from cultivation, mining, construction, and poor land use) Runoff from streets, lawns, and construction lots (nitrates and phosphates) Lake ecosystem nutrient overload and breakdown of chemical cycling Natural runoff (nitrates and phosphates Natural runoff (nitrates and phosphates Inorganic fertilizer runoff (nitrates and phosphates) To assess an area you must treat all levels of the system

Water ppm Phytoplankton ppm Zooplankton ppm Rainbow smelt 1.04 ppm Lake trout 4.83 ppm Herring gull 124 ppm Herring gull eggs 124 ppm Individuals work as well

Types of Flows: Transfer vs. Transformation Transfers  flow through the system, involving a change in location Transfers  flow through the system, involving a change in location Transformation  lead to interactions in the system, changes of state or forming new end products Transformation  lead to interactions in the system, changes of state or forming new end products -Example: Water processes Runoff = transfer, Evaporation = transformation Detritus entering lake = transfer, Decomposition of detritus is transformation of detritus is transformation

Precipitation to ocean Evaporation From ocean Surface runoff (rapid) Ocean storage Condensation Transpiration Rain clouds Infiltration and percolation Transpiration from plants Groundwater movement (slow) Runoff Surface runoff (rapid) Precipitation What type of System is this? Name the inputs, outputs, transfers and transformations

Systems and Energy We see Energy as an input, output, transfer, or transformation We see Energy as an input, output, transfer, or transformation Thermodynamics – study of energy Thermodynamics – study of energy 1 st Law: Energy can be transferred and transformed but it can never be created nor destroyed 1 st Law: Energy can be transferred and transformed but it can never be created nor destroyed So… So… All energy in living systems comes from the sun All energy in living systems comes from the sun Into producers through photosynthesis, then consumers up the food web Into producers through photosynthesis, then consumers up the food web

Sun Producers (rooted plants) Producers (phytoplankton) Primary consumers (zooplankton) Secondary consumers (fish) Dissolved chemicals Tertiary consumers (turtles) Sediment Decomposers (bacteria and fungi) Energy at one level must come from previous level

Using the first law of thermodynamics explain why the energy pyramid is always pyramid shaped (bottom bigger than top)

2 nd Law: With every energy transfer or transformation energy dissipates (heat) so the energy available to do work decreases 2 nd Law: With every energy transfer or transformation energy dissipates (heat) so the energy available to do work decreases Or in an isolated system entropy tends to increase spontaneously Or in an isolated system entropy tends to increase spontaneously Energy and materials go from a concentrated to a dispersed form The concentrated high quality energy is the potential energy of the system Energy and materials go from a concentrated to a dispersed form The concentrated high quality energy is the potential energy of the system The system becomes increasingly disordered The system becomes increasingly disordered Order can only be maintained through the use of energy Order can only be maintained through the use of energy

Heat First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Solar energy Producers (plants) Primary consumers (herbivores) Tertiary consumers (top carnivores) Secondary consumers (carnivores) Detritivores (decomposers and detritus feeders) Heat

What results from the second law of Thermodynamics?

Feedback loops Self regulation of natural systems is achieved by the attainment of equilibrium through feedback systems Self regulation of natural systems is achieved by the attainment of equilibrium through feedback systems Change is a result of feedback loops but there is a time lag Change is a result of feedback loops but there is a time lag Feedback occurs when one change leads to another change which eventually reinforces or slows the original change. Feedback occurs when one change leads to another change which eventually reinforces or slows the original change. Or… Or… Outputs of the system are fed back into the input Outputs of the system are fed back into the input

Positive feedback A runaway cycle – often called vicious cycles A runaway cycle – often called vicious cycles A change in a certain direction provides output that further increases that change A change in a certain direction provides output that further increases that change Change leads to increasing change – it accelerates deviation Change leads to increasing change – it accelerates deviation Example: Global warming 1. Temperature increases  Ice caps melt 2. Less Ice cap surface area  Less sunlight is reflected away from earth (albedo) 3. More light hits dark ocean and heat is trapped 4. Further temperature increase  Further melting of the ice

Solar radiation Energy in = Energy out Reflected by atmosphere (34%) UV radiation Absorbed by ozone Absorbed by the earth Visible light Lower stratosphere (ozone layer) Troposphere Heat Greenhouse effect Radiated by atmosphere as heat (66%) Earth Heat radiated by the earth

Negative feedback One change leads to a result that lessens the original change One change leads to a result that lessens the original change Self regulating method of control leading to the maintenance of a steady state equilibrium Self regulating method of control leading to the maintenance of a steady state equilibrium Predator Prey is a classic Example Predator Prey is a classic Example Snowshoe hare population increases Snowshoe hare population increases More food for Lynx  Lynx population increases More food for Lynx  Lynx population increases Increased predation on hares  hare population declines Increased predation on hares  hare population declines Less food for Lynx  Lynx population declines Less food for Lynx  Lynx population declines Less predation  Increase in hare population Less predation  Increase in hare population

Remember hare’s prey and other predators also have an effect

Most systems change by a combination of positive and negative feedback processes

Which of the populations show positive feedback? Which of the populations show negative feedback?

Positive or Negative? If a pond ecosystem became polluted with nitrates, washed off agricultural land by surface runoff, algae would rapidly grow in the pond. The amount of dissolved oxygen in the water would decrease, killing the fish. The decomposers that would increase due to the dead fish would further decrease the amount of dissolved oxygen and so on... If a pond ecosystem became polluted with nitrates, washed off agricultural land by surface runoff, algae would rapidly grow in the pond. The amount of dissolved oxygen in the water would decrease, killing the fish. The decomposers that would increase due to the dead fish would further decrease the amount of dissolved oxygen and so on... A good supply of grass for rabbits to eat will attract more rabbits to the area, which puts pressure on the grass, so it dies back, so the decreased food supply leads to a decrease in population because of death or out migration, which takes away the pressure on the grass, which leads to more growth and a good supply of food which leads to a more rabbits attracted to the area which puts pressure on the grass and so on and on....

End result? Equilibrium… A sort of equalization or end point A sort of equalization or end point Steady state equilibrium  constant changes in all directions maintain a constant state (no net change) – common to most open systems in nature Steady state equilibrium  constant changes in all directions maintain a constant state (no net change) – common to most open systems in nature Static equilibrium  No change at all – condition to which most natural systems can be compared but this does not exist Static equilibrium  No change at all – condition to which most natural systems can be compared but this does not exist Long term changes in equilibrium point do occur (evolution, succession) Long term changes in equilibrium point do occur (evolution, succession) Equilibrium is stable (systems tend to return to the original equilibrium after disturbances) Equilibrium is stable (systems tend to return to the original equilibrium after disturbances)

Equilibrium generally maintained by negative feedback – inputs should equal outputs

You should be able to create a system model. Observe the next two society examples and create a model including input, flows, stores and output

High Throughput System Model

High-quality energy Matter System Throughputs Output (intro environment) Unsustainable high-waste economy Low-quality heat energy Waste matter and pollution Inputs (from environment)

Low Throughput System Model

High-quality energy Matter Pollution prevention by reducing matter throughput Sustainable low-waste economy Recycle and reuse Pollution control by cleaning up some pollutants Matter output Low-quality energy (heat) Waste matter and pollution Matter Feedback Energy Feedback Inputs (from environment) System Throughputs Outputs (from environment)

Easter Island What are the statues and where are the trees? A case Study in unsustainable growth practices.

Evaluating Models Used when we can’t accurately measure the real event Used when we can’t accurately measure the real event Models are hard with the environment because there are so many interacting variables – but nothing else could do better Models are hard with the environment because there are so many interacting variables – but nothing else could do better Allows us to predict likelihood of events Allows us to predict likelihood of events But… But… They are approximations They are approximations They may yield very different results from each other or actual events They may yield very different results from each other or actual events There are always unanticipated possibilities… There are always unanticipated possibilities…

Anticipating Environmental Surprises Remember any action we take has multiple unforseen consequences Remember any action we take has multiple unforseen consequences Discontinuities = Abrupt shifts occur in previously stable systems once a threshold is crossed Discontinuities = Abrupt shifts occur in previously stable systems once a threshold is crossed Synergistic interactions = 2 factors combine to produce greater effects than they do alone Synergistic interactions = 2 factors combine to produce greater effects than they do alone Unpredictable or chaotic events = hurricanes, earthquakes, climate shifts Unpredictable or chaotic events = hurricanes, earthquakes, climate shifts s.shtml s.shtml s.shtml s.shtml

What can we do? Develop more complex models for systems Develop more complex models for systems Increase research on environmental thresholds for better predictive power Increase research on environmental thresholds for better predictive power Formulate possible scenarios and solutions ahead of time Formulate possible scenarios and solutions ahead of time

Systems Measurement Data Analysis System Modeling System Simulation System Optimization Define objectives Identify and inventory variables Obtain baseline data on variables Make statistical analysis of relationships among variables Determine significant interactions Construct mathematical model describing interactions among variables Run the model on a computer, with values entered for different variables Evaluate best ways to achieve objectives © 2004 Brooks/Cole – Thomson Learning

Other systems examples

Uranium 100% Electricity from Nuclear Power Plant 14% Resistance heating (100%) 90% Waste heat Passive Solar Sunlight 100% Waste heat 14% Transmission of electricity (85%) 17% Waste heat Power plant (31%) 54% Waste heat Uranium processing and transportation (57%) 95% Waste heat Uranium mining (95%) Energy Production

sun EARTH Natural Capital Air; water, land, soil, biodiversity, minerals, raw materials, energy resources, and dilution, degradation, and recycling services Economic Systems Production Consumption Heat Depletion of nonrenewable resources Degradation and depletion of renewable resources used faster than replenished Pollution and waste from overloading nature’s waste disposal and recycling systems Recycling and reuse Economics & Earth

Energy InputsSystemOutputs U.S. economy and lifestyles 84% 8% 4% 9% 7% 41% 43% Nonrenewable fossil fuels Nonrenewable nuclear Hydropower, geothermal, wind, solar Biomass Useful energy Petrochemicals Unavoidable energy waste Unnecessary energy waste