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Environmental Science
Carl Mitchell

Earths Environmental Systems Our planets environment consists of complex networks of interlinked systems. Earth uses cycles that shape the landscapes around us and guide the flow of key chemical elements and compounds that support life and regulate climate. Systems show several defining properties System is a network of relationships among parts, elements, or components that interact with and influence one another through the exchange of energy, matter, or information. Open Systems are systems that receive input of both energy and matter and produce outputs of both Closed Systems receive inputs and produce outputs of energy, but not matter. o in nature, no system is perfectly closed Energy inputs to the earths environmental systems include o Solar radiation o Heat released by geothermal activity o Organismal metabolism o Human activities (eg. Fossil fuel combustion) Information energy can come in the form of sensory cues from: o visual signs o Olfactory (chemical) signs o Magnetic signs o Thermal signs Inputs of matter occur when chemicals or physical material moves among systems o Eg. Seeds being dispered long distances o Migratory animals deposit waste far from where they consumed food Eg. Gulf of St. Lawrence receives inputs from the St. Lawrence, fishers harvest some of the systems output: matter and energy in the form of fish and plankton. o Output becomes input to the human economic system and to the digestive systems of the people who consumer seafood from the St. Lawrence Sometimes a systems output can serve as input to that same system o This is a circular process known as feedback loop Can be positive or negative In a negative feedback loop output that results from a system moving in one direction acts as input that moves the system in the other direction, o Input and output essentially neutralize each other o EG. Thermostat working to stabilize rooms temperature o EG. Our bodies, when we get too hot, our sweat glands pumpe out moisture that evaporates to cool us down. Most systems in nature involve negative feedback loops. Positive feedback loops have the opposite effect, rather than stabilizing a system, they drive it further toward one extreme or another. o eg. Populations growth, the more people who are born, the more there are to give birth to further people, increased output leads to increased input, leading to further increased output. o Positive feedback loops are rare in nature, common in natural systems altered by human impact. System is constantly active as input and outputs occur simultaneously. When processes within a system move in opposite directions at equivalent rates so that their effects balance out is called dynamic equilibrium o Dynamic because even though the state is balance, it is ever-changing
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