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Environmental Science
Carl Mitchell

Earths Environmental SystemsOur planets environment consists of complex networks of interlinked systemsEarth 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 propertiesSystem is a network of relationships among parts elements or components that interact with and influence one another through the exchange of energy matter or informationOpen Systems are systems that receive input of both energy and matter and produce outputs of bothClosed Systems receive inputs and produce outputs of energy but not matterin nature no system is perfectly closedEnergy inputs to the earths environmental systems includeSolar radiationHeat released by geothermal activityOrganismal metabolismHuman activities eg Fossil fuel combustionInformation energy can come in the form of sensory cues fromvisual signsOlfactory chemical signsMagnetic signsThermal signsInputs of matter occur when chemicals or physical material moves among systemsEg Seeds being dispered long distancesMigratory animals deposit waste far from where they consumed foodEg 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 planktonOutput becomes input to the human economic system and to the digestive systems of the people who consumer seafood from the St LawrenceSometimes a systems output can serve as input to that same systemThis is a circular process known as feedback loopCan be positive or negativeIn 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 Input and output essentially neutralize each otherEG Thermostat working to stabilize rooms temperatureEG Our bodies when we get too hot our sweat glands pumpe out moisture that evaporates to cool us downMost systems in nature involve negative feedback loopsPositive feedback loops have the opposite effect rather than stabilizing a system they drive it further toward one extreme or anothereg 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 outputPositive feedback loops are rare in nature common in natural systems altered by human impactSystem is constantly active as input and outputs occur simultaneouslyWhen processes within a system move in opposite directions at equivalent rates so that their effects balance out is called dynamic equilibriumDynamic because even though the state is balance it is everchangingHomeostasis is the tendency of a system to maintain constant or stable internal conditionsHomeostatic systems are often said to be in a stable or steady stateEarth is a homeostatic systemResistance refers to the strength of a systems tendency to remain constantResilience is a measure of how readily the system will return to its original state once its been disturbed It is difficult to understand systems fully by focusing on their individual components because systems can show emergent propertiesCharacteristics not evident in the components aloneIt is like saying the whole is more than the sum of its partsIf you had a tree in its components parts leaves branches you wouldnt be able to predict the whole trees emergent properties which include the role the tree plays as a habitat for birds etc You could analyze the trees chloroplasts but still be unable to understand the tree as habitatSystems have well defined boundariesComputerdesktop example
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