ESS midterm
Systems
System- a collection of parts that work together.
Emergent properties- Features of a system that don’t appear in the individual parts. The outcome of a system
Examining an issue or situation by looking at the whole system refers to a “”systems approach”, while looking at individual parts refers to a “reductionist approach”
Systems are made up of inputs, processes, and outputs
(input → process → output)
Positive feedback loop - output does not return into system, simply accumulates after the system is done, bad for environment
Negative feedback loop - output keeps the system in equilibrium
Inputs- anything that enters a system
Processes- changes made inside a system
Outputs- anything that exits a system
Matter and Energy
Everything in the universe is made of energy and matter
Energy is anything that helps the ability to do work
Transfer: energy or matter that moves without changing state or form (ex. Wind blowing, water flowing down a river)
Transformation: Energy or matter that moves and changes state or form (ex. Water evaporating into gas, chemical bonds breaking and creating different types of molecules.
Transfers and transformations are constantly happening everywhere
Energy takes many forms, thermal (heat), kinetic, electrical, gravitational, chemical, light, and nuclear.
Laws of thermodynamics:
1st law. Matter and energy cannot be created or destroyed, only change forms
2nd law. In every transformation, some energy will always change into heat
Ex. more energy goes into a battery than comes out
Stores and Flows
Stores: matter that stays in a system
Flows: energy or matter that enters and exits a system
Cycle: a system with looping flows of energy or matter
Open system: A system where energy and matter can flow in and out. (Ex. bodies, mechanics, etc)
Closed system: A system where energy can flow in and out but matter can't. (Ex. Earth)
Isolated system: A system where energy & matter can’t enter or exit.
Models
Models are used to represent understanding…
(ex. The paths and intensity of hurricanes are predicted with models)
Models that are too simple, or made with bad data or misconceptions, can be inaccurate.
Boxes on a system model are storages (where the energy sits when its not being transformed)
Arrows are flow
Example: ocean is a storage, when solar heat energy hits the water the water evaporates (evaporation is both a transfer and transformation, liquid to gas but water molecules are moving up to clouds),
1. Fundamentals of Systems
System: A collection of interacting, interrelated, or interdependent parts that work together to form a complex whole. Systems can be biological (an organism), mechanical (an engine), or ecological (a forest).
Emergent Properties: These are features or behaviors of a system that do not exist in the individual components but arise from their interaction.
Example: A single neuron cannot think, but a system of neurons (the brain) creates consciousness.
Systems Approach: A holistic way of examining an issue by looking at the whole system and the relationships between its parts. This is often used in environmental science to understand how one change impacts the entire biosphere.
Reductionist Approach: Breaking down a system into its smallest parts to understand them individually. While useful for specific mechanics, it may miss emergent properties.
2. System Mechanics: Inputs, Processes, and Outputs
Systems function through a continuous flow of resources through three stages:
Inputs: Anything that enters the system (e.g., solar energy, water, matter).
Processes: The internal actions or transfers that change the inputs (e.g., photosynthesis, respiration, digestion).
Outputs: Anything that exits the system as a result of the process (e.g., heat, waste, oxygen).
3. Feedback Loops and Equilibrium
Feedback loops occur when the output of a process affects the input, either enhancing or dampening the original process.
Positive Feedback Loop: The output of a system causes a further increase or accumulation, leading the system away from its equilibrium point. These are often destabilizing and can lead to a "tipping point."
Example: Global warming melts polar ice $\rightarrow$ less sunlight is reflected (lower albedo) $\rightarrow$ more heat is absorbed $\rightarrow$ more ice melts.
Negative Feedback Loop: The output works to counteract the input, bringing the system back to a state of equilibrium (homeostasis). These are self-regulating and promote stability.
Example: Your body temperature rises $\rightarrow$ you sweat $\rightarrow$ evaporation cools the body $\rightarrow$ temperature returns to normal.
4. Matter and Energy
Everything in a system consists of matter (anything with mass and volume) and energy (the capacity to do work).
Transfer: Occurs when energy or matter flows through a system without changing its state.
Example: Water moving in a current or energy moving through a food chain.
Transformation: Occurs when energy or matter changes state or form.
Example: Chemical energy in wood transforming into thermal energy (heat) during combustion.
Laws of Thermodynamics
Law of Thermodynamics (Law of Conservation): Energy cannot be created or destroyed, only transformed from one form to another. The total energy in an isolated system remains constant.
Law of Thermodynamics: In every energy transformation, there is an increase in entropy (disorder). No transformation is efficient; some energy is always lost to the environment as low-grade heat.
5. Stores, Flows, and System Types
Stores (Storages): Places where matter or energy is kept within a system (represented by boxes in models).
Flows: The movement of matter or energy between stores (represented by arrows).
Types of Systems:
Open System: Both energy and matter are exchanged with the surroundings (e.g., most ecosystems, the human body).
Closed System: Energy is exchanged with the surroundings, but matter is not (e.g., Planet Earth, as matter exchange is negligible compared to the massive energy intake from the sun).
Isolated System: Neither energy nor matter is exchanged. These are theoretical and do not exist naturally, though the entire Universe is sometimes considered one.
6. Modeling Systems
Models are simplified versions of reality used to understand complex interactions and predict future outcomes.
Advantages: They help visualize complex processes and allow for predictions (like hurricane tracking or climate change projections).
Limitations: Models are only as good as the data provided. If they are oversimplified or based on incorrect assumptions, they can lead to inaccurate conclusions.
Visual Representative:
Boxes: Represent storages of energy or matter.
Arrows: Represent flows (inputs/outputs).