1.2 Systems and Models Significant ideas: A systems approach can help in the study of complex environmental issues. The use of systems and models simplifies interactions but may provide a more holistic view without reducing issues to single processes. Big Questions What strengths and weaknesses of the systems approach and the use of models have been revealed through this topic?

Systems A system is a set of inter-related parts working together to make a complex whole in order to perform a particular function Can be living or non-living Exits on any scale = cells, you, a bicycle, a car, your home, a pond, and ocean, a smart phone, a farm, the economy, the Earth, the Universe All systems have inputs and outputs of energy, matter, or information All systems have storages, flows, processes, and feedback mechanisms Page -19-20

Systems This course focuses hugely on SYSTEMS Material an energy undergo transfers (change in location of matter/energy) and transformations (change in chemical nature, change in state, or change in energy) in flowing from one storage to the next Transfers: (ex) The movement of material through living organisms Movement of material in non-living process The movement of energy Transformations Matter to matter Energy to energy Matter to energy Energy to matter This course focuses hugely on SYSTEMS The systems approach is a way of visualizing a complex set of interactions which may be ecological or societal

All Systems Have Represented By: STORAGES of stores of matter and energy A box FLOWS into, through, and out of the system Arrows INPUTS Arrows in OUTPUTS Arrows out Boundaries Lines PROCESSES which transfer or transform energy or matter from storage to storage Ex: respiration, precipitation, diffusion

3 types: opened, closed, isolated Types of Systems 3 types: opened, closed, isolated Opened Systems Exchanges matter and energy with its surroundings Most natural living systems are open systems Ex: ecosystems (lakes, forests, etc)…why?

2. Closed Systems https://www.youtube.com/watch?v=cQUkX9S06qw A system in which energy is exchanged across boundaries of the system, but matter is not Extremely rare in nature Ex: the Earth (almost a closed system) Light energy enters, and some is returned to space as heat Most closed systems are artificial and for experimental purposes Ex: the hydrological, carbon, or nitrogen cycles when considered on a global scale https://www.youtube.com/watch?v=cQUkX9S06qw

Light Energy from the Sun Long-wave (heat) energy returned to space

Biosphere 2 https://www.youtube.com/watch?v=oUJGR6qNVzA https://www.ted.com/talks/jane_poynter_life_in_biosphere_2 P. 22

3. Isolated Systems A system in which neither energy nor matter is exchanged with its environment Do not exist naturally No such system actually exists with the possible exception of the entire universe

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Models A model is a simplified description to show the structure and working of a system Models can be used to show the flows, storage, and linkages within ecosystems While they are unable to show much of the complexity of the real system, they help us to understand ecosystem function better In this class we will… Model climate and climate change Model human and species population dynamics Model groundwater flow Model different types of energies Model landfills and pollution clean up And others

 A model inevitably involves some approximation and therefore loss of accuracy. Strengths:  Simple to work with allow scientist to predict changes See patterns Used to visualize very small or very large things inputs can be changed and outcomes examined without having to wait for real events. results can be shown to scientists and the public Limitations: might not be totally accurate environmental factors are very complex different models use slightly different data to calculate predictions rely on the expertise of people making them different people may interpret them in different ways vested interests might hijack them politically any model is only as good as the data goes in and these may be suspect different models may show different effects using the same data

Gaia Hypothesis – A model of the Earth the earth is a planet sized organism and the atmosphere is its organ that regulates it and connects all its parts the temperature and composition of the Earth's surface are actively controlled by life on the planet. It suggests that if changes in the gas composition, temperature or oxidation state of the Earth are caused by extraterrestial, biological, geological, or other disturbances, life responds to these changes by modifying the abiotic environment through growth and metabolism. In simpler terms, biological responses tend to regulate the state of the Earth's environment in their favor. http://ccl.northwestern.edu/netlogo/models/Daisyworld

Application and skills Construct a system diagram or a model from a given set of information Draw a systems diagram for a simplified human body system.

Application and skills Evaluate the use of models as a tool in a given situation, for example, climate change predictions Below are 4 different climate model simulations. You should be able to discuss the strengths and weakness of each of these models. Which model do you believe is the best for understanding climate change? Justify your reasoning! ​ Concord Consortium Climate Model Watch video only Window's to the Universe Climate Model Koshland Science Museum Climate Model UCAR Climate Model

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1.3 Energy and Equilibria Significant Ideas The laws of thermodynamics govern the flow of energy in a system and the ability to do work Systems can exist in alternative stable states or as equilibria between which there are tipping points Destabilizing position feedback mechanisms will drive systems toward these tipping points, whereas stabilizing negative feedback mechanisms will resist such changes Big questions: What strengths and weaknesses of the systems approach and the use of models have been revealed through this topic How are the issues addressed in this topic of relevance to sustainability or sustainable development? The principle of conservation of energy can be modeled by the energy transformations along food chains and energy production systems: what are the strengths and limitations for such models? How do the delays involved in feedback loops make it difficult to predict tipping points and add to the complexity of modelling systems? Do the benefits of the models used to predict tipping points outweigh their limitations? How does sustainability reduce the change that tipping points will be reached?

1.3 Energy and Equilibria – energy in systems 1st Law of Thermodynamics = energy is neither created nor destroyed (but can be transferred & transformed) Energy can change from one form to another (light to heat) but no new energy is created. There has always been, and always will be, exactly the same amount of energy in the universe Sometimes called conservation of energy.

1st Law of Thermodynamics Ex: sunlight -What happens to all of the light that reaches Earth? 30% reflected back into space 50% converted to heat 19% powers hydrologic cycle 1% used for photosynthesis That’s 100%

1st Law of Thermodynamics In a food chain: Light is changed to chemical energy through photosynthesis and transferred again as chemical energy to an herbivore and then carnivore. The energy at one level must come from the previous level Hence, the 1st Law of Thermodynamics explains why the Energy Pyramids is always bigger on the bottom than on the top