Post on 09-May-2018
Overview of Chapter 1
Human Impacts on The Environment
Population, Resources and the Environment
Environmental Sustainability
Environmental Science
Addressing Environmental Problems
The Environment (Earth)
Life has existed on earth for 3.8 billion years
Earth well suited for life 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 Environment—Population
Expected to add several billion more people in 21st
century
Earth’s Human Population is over 6 billion
Growing exponentially
Population
1 in 4 people live in extreme poverty
Cannot meet basic need for food, clothing, shelter, health
Difficult to meet population needs without exploiting earth’s resources
Gap Between Rich and Poor
Highly Developed Countries (HDC)
Complex industrialized bases, low population growth, high per capita incomes
Ex: US, Canada, Japan
Less Developed Countries (LDC)
Low level of industrialization, very high fertility rate, high infant mortality rate, low per capita income
Ex: Bangladesh, Mali, Ethiopia
Overpopulation
People overpopulation
Too many people in a given geographic area
Problem in many developing nations
Consumption overpopulation
Each individual in a population consumes too large a share of the resources
Problem in many highly developed nations
Ecological Footprint
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 Productive Land and Water by Human Population)
1.8 hectares
Current Global Ecological Footprint of each person
2.7 hectares
IPAT Model
Measures 3 factors that affect environmental impact (I)
I = P A T
Environmental
Impact
Number
of people
Affluence per
person
Environmental
effect of
technologies
Environmental Sustainability
The ability to meet current human need for natural resources without compromising the needs of future generations
Requires understanding:
The effects of our actions on the earth
That earth’s resources are not infinite
Tragedy of the Commons
Garrett Hardin (1915-2003)
Solving Environmental Problems is result of struggle between:
Short term welfare
Long term environmental stability and societal welfare
Common pool resources
Garrett used Common Pastureland in medieval Europe to illustrate the struggle
Sustainable Development
Economic development that meets the needs of the present generation without compromising future generations
Environmental Science
An interdisciplinary study of human relationship with other organisms and the earth
Biology
Ecology
Geography
Chemistry
Geology
Physics
Economics
Sociology
Demography
Politics
Earth As a System
System A set of components that interact and
function as a whole
Global Earth Systems Climate, atmosphere, land, coastal zones,
ocean
Ecosystem A natural system consisting of a community of
organisms and its physical environment
System approach to environmental science Helps explain how human activities affect
global environmental parameters
Earth Systems
Most of earth’s systems are in dynamic equilibrium or steady state Rate of change in one direction equals that in
the other
Feedback Negative feedback- change triggers a
response that counteracts the changed condition
Positive feedback- change triggers a response that intensifies the changing condition
Controls and Variables in Experiment
Variable
A factor that influences a process
The variable may be altered in an experiment to see its effect on the outcome
Control
The variable is not altered
Allows for comparison between the altered variable test and the unaltered variable test
Inductive and Deductive Reasoning
Inductive Reasoning Used to discover general principles
Seeks a unifying explanation for all the data available
Ex: 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
Deductive Reasoning
Proceeds from generalities to specifics
Adds nothing new to knowledge, but makes relationships among data more apparent
Ex:
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
Five steps are idealistic
Case Study: Lake Washington
Assessing Environmental ProblemCase Study: Lake Washington
Large, freshwater pond
Suburban sprawl in 1940’s
10 new sewage treatment plants dumped effluent into lake
Effect = excessive cyanobacteria growth that killed off fish and aquatic life
Scientific Assessment
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
After analyzing many choices, chose new location (freshwater) and greater treatment for sewage to decrease nutrients in effluent
Assessing Environmental ProblemCase Study: Lake Washington
Public Education/Involvement Educated public on why changes were
necessary
Political Action Difficult to organize sewage disposal in so
many municipalities
Changes were not made until 1963!
Evaluation Cyanobacteria slowly decreased until 1975
(gone)
Assessing Environmental ProblemCase Study: Lake Washington