Fundamental Issues in Environmental Science

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Chapter 1

• Fundamental Issues in Environmental Science

Big Question Why Is Science Necessary to
Solve Environmental Problems?
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Case StudyEaster Islandcollapse of a society
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Human Population The BasicEnvironmental Problem

• In the past 35 years, the number of people in the
  world more than doubled, from 2.5 billion to over
  6.6 billion
• Our rapidly increasing population underlies all
  environmental problems because most environmental
  damage results from the very large number of
  people on Earth

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Sustainability

• Use it, but dont use it up
• Other uses of the term sustainability
• sustainable society
• sustainable economy
• Sustainable development
• sustainable architecture

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Earths Carrying Capacity

• How many people can Earth sustain?
• Carrying capacity is usually defined as the
  maximum number of individuals of a species that
  can be sustained by an environment over the long
  term

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• Earths human carrying capacity depends in part
  on how we want to live, and how we want those who
  follow us to live

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A Global Perspective

• Today our actions are experienced worldwide
• Life makes Earths environment unlike that of
  other planets

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• The Gaia hypothesis proposes that the global
  environment has been profoundly changed by life
  throughout the history of life on Earth, and that
  these changes have improved the chances that life
  on Earth will continue

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Cities Affect the Environment

• We are becoming an urban species, and our effects
  on the environment are more and more the effects
  of urban life
• We must look more closely at the effects of
  urbanization

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People and Nature

• Principle of environmental unity
• everything affects everything else
• We depend on nature for many natural service
  functions

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• We are becoming more Earth-centered, spending
  more time in nature for recreation and spiritual
  activities

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Science and Values

• Before we decide what kind of environment we
  want, we need to know what is possible
• Science is a process of discovery
• Sometimes changes in ideas are small
• Sometimes a science undergoes a fundamental
  revolution in ideas

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• Science is one way of looking at the world
• Begins with observations about the natural world
• From these observations, scientists formulate
  hypotheses that can be tested
• Science does not deal with things that cannot be
  tested by observation
• the ultimate purpose of life
• the existence of a supernatural being
• standards of beauty or issues of good and evil
• Ideas are scientific if it is possible to
  disprove them

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• Scientists rely on critical thinking
• Relies on disciplined thinking using intellectual
  standards, effective communication, clarity, and
  commitment to developing scientific knowledge and
  skills

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What is Environmental Science?

• A group of sciences that attempt to explain how
  life on Earth is sustained, what leads to
  environmental problems, and how these problems
  can be solved
• Also is often linked with nonscientific fields
  that have to do with how we value the environment
• Deals with many topics that have great emotional
  effects on people

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Placing a Value on the Environment

• Utilitarian justification
• values the environment it is useful economically
  or for survival
• Ecological justification
• Values the larger life-support functions of the
  environment
• Aesthetic justification
• values beauty
• Moral justification
• based on ones view of right and wrong, and
  extending inherent rights beyond humans

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Solving Many EnvironmentalProblems Involves
Systems and Ratesof Change

• A system is a set of parts that function together
  to act as a whole
• City
• River

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• Systems respond to inputs and have outputs
• Feedback - the output of the system also serves
  as input and leads to further changes in the
  system
• Negative feedback occurs when an increase in
  output leads to a decrease in the output
• Positive feedback occurs when an increase in
  output leads to a further increase in the output

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Positive Feedback Off Road Vehicles and Erosion
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• Some situations involve both positive and
  negative feedback
• Example changes in human populations of large
  cities

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• Which kind of feedback is more desirable?
• For most of human history, strong negative
  feedback limited growth of the human population

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• Exponential growth is an important outcome of
  positive feedback
• Exponential growth is incompatible with
  sustainability

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Environmental Unity

• It is impossible to change only one thing
  everything affects everything else
• Changes in one part of a system often have
  secondary and tertiary effects within the system
  and effects on adjacent systems

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Example Deforestation in Amboseli National Park

• Loss of forests was originally blamed on
  overgrazing by cattle

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• In fact, rainfall cycles changed hydrology and
  soil conditions, which in turn changed the
  vegetation and animals of the area

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Changes and Equilibrium in Systems

• When the input to a system is equal to the
  output, the system is said to be in a steady
  state
• Steady state is a dynamic equilibrium because
  something is still happening

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• If input is less than the output, the storage
  compartment will shrink
• Groundwater extraction
• If input exceeds
• output, the storage
• compartment will
• expand
• Groundwater
• pollution

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• Average residence time - how long it takes for a
  particular material to be cycled through the
  system
• Systems with a short residence time are
  susceptible to rapid pollution
• Systems with long residence time are slower to be
  polluted, but take longer to be cleaned up
• Are natural systems a steady state, or do they
  change naturally?

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• To effectively manage natural systems, we need to
  understand
• the types of disturbances and changes that are
  likely to occur
• the time periods over which changes occur
• the importance of each change to the long-term
  productivity of the system.

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Biota Biosphere and Sustaining Life

• Biota - all living things (animals and plants,
  microorganisms) within a given area
• Biosphere - the region of Earth where life exists
• What is needed to sustain life?
• there must be several species within a system
  that includes air and water to transport
  materials and energy an ecosystem

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Ecosystems

• A community of organisms and their local
  nonliving environment in which matter (chemical
  elements) cycles and energy flows
• Vary in size, from the smallest puddle of water
  to a large forest, or the entire global biosphere
• Ecosystem borders may be clearly or vaguely
  defined

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Several characteristics of environmental
systemsmake solving environmentalproblems harder
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• Lag time is the time between a stimulus and a
  systems response to that stimulus
• If there is a long delay between stimulus and
  response, then the resulting changes are much
  more difficult to recognize

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• Exponential growth and long lag time may allow a
  population to eventually exceed the carrying
  capacity, resulting in overshoot and a decline
  collapse in the population

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• Some environmental changes may be irreversible
  over time periods of hundreds or thousands of
  years
• Today we may be using more than Earth can replace
• Ecological footprint - the total area each person
  requires based on the resources used and the
  waste produced

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• We may be consuming about 20 more of Earths
  biological productivity than is replaced each
  year

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The Precautionary PrincipleWhen in Doubt, Play
It Safe

• It can be difficult to prove with absolute
  certainty how human activities lead to local and
  global environmental problems
• When there is a threat of serious environmental
  damage, we should not wait for certain scientific
  proof before taking steps to prevent potential
  harm

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• How much proof do we need before acting?
• We need to examine the benefits and costs of
  taking a particular action versus taking no
  action
• The Precautionary Principle is a proactive tool