Transcript Environmental Science: Earth as a Living Planet

Environmental Science:
Earth as a Living Planet
Chapter 1
Major Themes of
Environmental Science
 World Population
 In A.D. 1- 100 Million people
 In 1960- 3 Billion people
 Today- 6.7 Billion people
 Projected: 10 Billion by 2040
 It took human population almost
2000 years to get to 3 billion, only
40+ years to add 3 billion more
Problem?
 The Earth has not grown any larger and
the abundance of its resources has not
increased
 Can the Earth SUSTAIN all these
people?
 What is the maximum number of people
that Earth can support? (remember:
Easter Island)
World Population
 How many people the Earth can sustain
depends on science and values and is
also a question about people and
nature.
 What quality of life are people willing
to accept?
 The poorer that quality, the greater the
number of people that can be
squeezed onto the Earth’s surface
Human Population Growth
John Eli Miller Family
 Of 7 children born to John Miller, 5
survived him
 Of 63 grandchildren, 61 survived him
 Of the 341 great-grandchildren (born to
55 married grandchildren- an average
of slightly more than 6 children per
parent- 338 survived him)
John Eli Miller Family
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Modern Population
Explosion
 Major factors in population:
 Supply of Food
 Supply of Clothing
 Shelter
 Decreased death rates (medical
improvement)
 As a result, the human population has
increased greatly, threatening the
environment
World Population
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Consequences of Rapid
Population Growth
 FAMINE is one of the things that
happen when a human population
exceeds its environmental resources
 In 1970’s, following a drought in the
Sahel Region, 500,000 Africans starved
to death and several million more were
permanently affected by malnutrition
FAMINE
 In 1980’s - In one year
during that period, as
many as 22 African
nations suffered
catastrophic food
shortages and 150
million Africans faced
starvation
 There is a continuing
food crisis in Southern
Africa (Malawi, Zambia
and Zimbabwe)
Reasons for Famine?
 Drought
 Size of Population affected by drought-
competing for resources
 Changing climate- partly because of
human activities
 Poor farming practices- erosion of soil
 Deforestation
We are forced to confront
a choice
 Which is more important,
the survival of people alive
today or conservation of the
environment, on which
future food production and
human life depend?
An Urban
World
 With economic
development, comes
URBANIZATION
 Urbanization =
people move from
farms to cities and
then perhaps to
suburbs
 Cities and towns
increase in size
 Cities are commonly
located near rivers
and coastlines
Destroying Wetlands
 Urban sprawl often overtakes good
agricultural land of river floodplains as
well as coastal wetlands, which are
important habitats for many rare and
endangered species.
 As urban areas expand, wetlands are
filled in, forests are cut, and soils
covered over with pavement and
buildings
Urban Sprawl
 In developed countries, 75% of the
population live in urban areas, with
25% in rural areas
 In developing countries, only 40% of
the people are city dwellers
 It is estimated that by 2025 almost twothirds of the population (5 billion
people) will live in cities
Largest
Cities
 In 1999, Tokyo,
Japan was the
world’s largest
city
 In 2015, Tokyo will
still be the world’s
largest city with an
estimated
population of 28.9
million
 Megacities- at least
8 million people
 Increased from 2
(NY and LA) to 23 in
1995
Megacities
 Most Megacities- 17- are in the
developing world
 It is estimated that by 2015- the
world will have 36 Megacities,
23 of them will be in Asia
 Environmental issues have always
focused on non-urban issues
(wildlife, etc.) but needs to shift
to urban issues
Sustainability
 What is sustainability?
 Refers to resources and their environment
Sustainable Resource Harvest- the same
quantity of that resource can be harvested
each year for an unlimited or specified
length of time without decreasing the
ability of that resource to continue to
produce the same harvest level
Sustainable Ecosystem
 An ecosystem that is still able to
maintain its essential functions and
properties even though we are
harvesting one of its resources
Sustainable Development
 A society can continue to develop
its economy and social interactions
and also maintain its environment
for an indefinite time
Carrying Capacity
 Related to sustainability
 The maximum number of individuals of
a species that can be sustained by an
environment to sustain that same
amount in the future
 Question: What is the maximum
number of people that the Earth
can sustain?
People and Nature
 People and nature are intimately
integrated- each affects the other.
 We depend on nature for our lives
 We depend on nature for beauty and
recreation
 We affect nature
Gaia Hypothesis
 Originated by British chemist James
Lovelock and American biologist Lynn
Margulis
 Proposes that the environment at a
global level has been profoundly
changed by life over the history of life
on Earth and that these changes have
tended to improve the chances for the
continuation of life.
Placing a Value on the
Environment
 How do we place a value on any aspect
of our environment?
 The value of the environment is based
on eight justifications: aesthetic,
creative, recreational, inspirational,
moral, cultural, ecological, and
utilitarian
Utilitarian Justification
 Sees some aspect of the environment
as valuable because it benefits
individuals economically or is directly
necessary to human survival
 Example: Mangrove Swamps provide
shrimp that are the basis of the
livelihood of the fisherman
Ecological Justification
 An ecosystem is necessary for the
survival of some species of interest to
us, or that the system itself provides
some benefit.
 Example: Mangrove Swamps provide
habitat for marine fish, and although we
do not eat Mangrove Trees, we may eat
the fish that depend on them.
Aesthetic Justification
 Our appreciation of the beauty of
nature
 Example: When people grieve
following the death of a loved one, they
typically seek out places with grass,
trees and flowers and thus we decorate
our graveyards
Recreational Justification
 People use wilderness for recreation
 Example: White water rafting, fishing,
and hiking
Inspirational Justification
 Conservation of nature can be based on
its benefits to the human spirit
Example: Religious Retreats
Creative Justification
 Nature is an aid to human creativity
 Example: Artists, poets and others find
a source of their creativity in their
contact with nature
Moral Justification
 Has to do with the belief that various
aspects of the environment have a right
to exist and that it is our moral
obligation to allow them to continue or
help them to persist.
 Example: Species have a moral right
to exist
Do Rocks Have Rights?
 The United Nations General Assembly
World Charter for Nature, signed in
1982, states that species have a moral
right to exist.
The Big Question
 DO we have a moral obligation to future
generations? to leave the
environment in good condition for
our descendants, OR
Are we at liberty to use
environmental resources to the
point of depletion within our own
lifetime?