Chapter 1
Introducing Environmental Science and
Stability
Overview of Chapter 1
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Human Impacts on The Environment
Population, Resources and the Environment
Environmental Sustainability
Environmental Science
Assessing Environmental Problems
The Environment (Earth)
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Life has existed on earth for 3.8 billion
years
Earth well suited for life
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Water covers ¾ of planet
Habitable temperature
Moderate sunlight
Atmosphere provides oxygen and carbon
dioxide
Soil provides essential minerals for plants
But humans are altering the planet; not
always in positive ways
Human Impacts on EnvironmentPopulation
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Earth’s Human Population
is over 6 billion
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Growing exponentially
Expected to add several
billion more people in 21st
century
Increase will adversely
affect living conditions
in many areas of the
world
Population
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Globally, 1 in 4 people
lives in extreme poverty
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Cannot meet basic need
for food, clothing, shelter,
health
Difficult to meet
population needs without
exploiting earth’s
resources
Gap Between Rich and Poor
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Highly Developed Countries (HDC)
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Complex industrialized bases, low population
growth, high per capita incomes
Ex: US, Canada, Japan
Less Developed Countries (LDC)
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Low level of industrialization, very high
fertility rate, high infant mortality rate, low
per capita income
Ex: Bangladesh, Mali, Ethiopia
Types of Natural Resources
Overpopulation
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People overpopulation
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Too many people in a given geographic area
Problem in many developing nations
Consumption overpopulation
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Each individual in a population consumes too
large a share of the resources
Problem in many highly developed nations
Ecological Footprint
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The average amount of land, water and ocean
required to provide that person with all the
resources they consume
Earth’s Productive Land and Water
11.4 billion
hectares
Amount Each Person is Allotted (divide 1.9 hectares
Productive Land and Water by Human
Population)
Current Global Ecological Footprint of 2.3 hectares
each person
Ecological Footprint Comparison
IPAT Model
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Measures 3 factors that affect
environmental impact (I)
Environmental
Impact
Affluence per
person
I=P A
Number
of people
T
Environmental
effect of
technologies
Environmental Sustainability
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The ability to meet current human need for
natural resources without compromising
the needs of future generations
Requires understanding:
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The effects of our actions on the earth
That earth’s resources are not infinite
Tragedy of the Commons
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Garrett Hardin (1915-2003)
Solving Environmental Problems is result of
struggle between:
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Short term welfare
Long term environmental stability and societal
welfare
Garrett used Common Pastureland in
medieval Europe to illustrate the struggle
Sustainable Development
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Economic development that meets the needs
of the present generation without
compromising future generations
Environmental Science
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An interdisciplinary study of human relationship
with other organisms and the earth
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Biology
Ecology
Geography
Chemistry
Geology
Physics
Economics
Sociology
Demography
politics
Earth As a System
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System
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Global Earth Systems
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Climate, atmosphere, land, coastal zones, ocean
Ecosystem
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A set of components that interact and function
as a whole
A natural system consisting of a community of
organisms and its physical environment
System approach to environmental science
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Helps us understand how human activities
effect global environmental parameters
Earth Systems
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Most of earth’s systems are in dynamic
equilibrium or steady state
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Rate of change in one direction equals that in
the other
Feedback
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Change in 1 part of system leads to change in
another
Negative feedback- change triggers a response
that counteracts the changed condition
Positive feedback- change triggers a response
that intensifies the changing condition
Scientific Method
Controls and Variables in Experiment
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Variable
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A factor that influences a process
The variable may be altered in an experiment
to see its effect on the outcome
Control
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The variable is not altered
Allows for comparison between the altered
variable test and the unaltered variable test
Inductive and Deductive Reasoning
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Inductive Reasoning
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Used to discover general principles
Seeks a unifying explanation for all the data
available
Ex:
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FACT: Gold is a metal heavier than water
FACT: Iron is metal heavier than water
FACT: Silver is a metal heavier than water
CONCLUSION (based on inductive reasoning): All
metals are heavier than water
Conclusions reached with inductive reasoning
may changed with new information
Inductive and Deductive Reasoning
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Deductive Reasoning
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Proceeds from generalities to specifics
Adds nothing new to knowledge, but makes
relationships among data more apparent
Ex:
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GENERAL RULE: All birds have wings
SPECIFIC EXAMPLE: Robins are birds
CONCLUSION (based on deductive reasoning): All
Robins have wings
Five Stages to
Addressing An
Environmental Problem
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Five steps are
idealistic
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Real life is rarely so
neat
Following Slides are
Case Study Using the
Five Stages
Assessing Environmental Problem
Case Study: Lake Washington
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Large, freshwater pond
Suburban sprawl in 1940’s
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10 new sewage treatment
plants dumped effluent into
lake
Effect = excessive
cyanobacteria growth that
killed off fish and aquatic
life
Assessing Environmental Problem
Case Study: Lake Washington
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Scientific Assessment
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Aquatic wildlife assessment done in 1933 was
compared to the 1950 assessment
Hypothesized treated sewage was introducing
high nutrients causing growth of cyanobacteria
Risk Analysis
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After analyzing many choices, chose new
location (freshwater) and greater treatment
for sewage to decrease nutrients in effluent
Assessing Environmental Problem
Case Study: Lake Washington
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Public Education/Involvement
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Political Action
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Educated public on why changes were
necessary
Difficult to organize sewage disposal in so
many municipalities
Changes were not made until 1963!
Evaluation
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Cyanobacteria slowly decreased until 1975
(gone)
Assessing Environmental Problem
Case Study: Lake Washington
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Results!