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Sunday, 23 December 2012

ES 2 - Principles


Topic 2 - Principles
Science
-          Methodical, logical process for gaining knowledge about natural phenomena
-          Cumulative body of knowledge produced by informed, learned scholars
-          Process based on careful observation & hypothesis testing
-          Way for us to explain how the natural world works
Science Depends on Skepticism & Accuracy
-          Scientists unbiased
-          Accuracy
-          Reproducibility (results repeatability = replication)
Deductive Reasoning
-          Logical reasoning from general to specific
Inductive Reasoning
-          Reasoning from many observations to produce general rule
·         Recognize role of insight, creativity, aesthetics, luck in research
Hypothesis
-          Testable explanation
Scientific theory
-          Explanation supported by many tests, considered reliable by experts
Probability
-          Likeliness of something to occur
-          Confidence increased by result comparison with a random sample / large group
Statistics
-          Test to calculate probability of observed result to occur by chance
-          Ecological test usually significant if probability <5%
-          Larger size, more confidence
Experimental design
-          Natural experiment
o   Happened events
-          Manipulative experiment
o   Conditions altered for 1 variable, others constant
-          Controlled study
o   Compare treatment group to control group
-          Blind experiment
o   Treated group unknown to researcher till data analyzed
-          Double-blind experiment
o   Treated group unknown to researcher & subject
Models
-          Simple representations of phenomena
-          Eg: physical model, model organism, math model
-          To study complex system, predict condition effect that are too difficult to create / control
System
-          Networks of interdependent components and processes, with flowing material & energy
-          Central concept in environmental science
-          Ecosystem, climate sys, geologic sys, economic sys
Components
-          State variables
o   Store resources (matter / energy), have pathways to move resources between variables
o   Eg: grass, rabbits (links in food chain)
System characteristics
-          Closed
o   Self-contained, exchanges no matter / energy outside
-          Open
o   Exchanges matter / energy from surroundings
-          Throughput
o   Energy / matter flow into, through, out of system
-          Positive feedback loop
o   Self-perpetuating, state variable increase cause further increase
-          Negative feedback loop
o   Suppresses change within system, maintain stability
-          Emergent properties
o   Characteristics of functioning system quantitatively/qualitatively more than sum of system’s parts
System stability
-          Equilibrium
o   Dynamic state where system stable over time (homeostasis)
-          Disturbance
o   Periodic destructive events (fire & flood)
-          Resilience
o   Disturbance recover ability
-          State Shift
o   Severe disturbance, system x return normal, state variable change significantly
Consensus & Conflict
-          Scientific consensus
o   General agreement of scholars from scientists collaborating in cumulative, self-correcting process
-          Paradigm shifts
o   Changes in explanatory framework when scientists agree old explanation works no more
Environmental Science
-          Use of scientific method to study environment processes & systems
Environmentalism
-          Working to influence attitudes / policies affecting environment



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