Key Themes in Environmental
Science
Environmental science is a group of
sciences that attempts to explain how life
on Earth is sustained, what leads to
environmental problems and how these
problems can be resolved
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
Key Themes in Environmental Science
Human population growth
1.
The environmental problem
Sustainability
2.
The environmental goal
A global perspective
3.
Many environmental problems require global solutions
An urbanizing world
4.
Large populations live and work in urban environments
People and nature
5.
Both are intimately integrated and affect each other
Science
6.
Science can provide solutions
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
1. Human Population Growth
In some ways the
underlying issue of the
environment
World population (World
Bank Pop. Statistics)
1961:
1971:
1981:
1991:
2001:
2011:
±3.1 billion
±3.8 billion
±4.5 billion
±5.4 billion
±6.1 billion
±7 billion
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
Population Growth in South Africa
Population of South Africa
1961 - 2011
60
40
30
20
10
Year
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
2011
2009
2007
2005
2003
2001
1999
1997
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
1971
1969
1967
1965
1963
0
1961
Population (in millions)
50
1. Human Population Growth
Famine and Food Crises
Following a drought in the Sahel region during the 1970’s 500
000 people starved to death while several million more were
permanently affected by malnutrition
Famines occur due to complex system interactions
(environmental, socio-economic, technological, population
numbers)
As of 16 Jan 2013 the UCL Department of Space and Climate
Physics estimates that ± 98 million people live under
exceptional drought conditions
This is defined as exceptional and widespread crop and pasture
losses; exceptional risk of fire; shortage of water in reservoirs,
streams and wells creating water emergencies
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
2. Sustainability
In the context of geologic time the changes we made to
the environment will be erased
Sustainability has two formal scientific meanings:
Sustainability of resources (e.g. global fish stocks)
Sustainability of an ecosystem
Carrying capacity: the maximum number of individuals of
a species that can be sustained by an environment
without decreasing the capacity of the environment to
sustain that same number in the future.
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
3. A Global Perspective
Impacts can transcend national boundaries
Some impacts can even reach global proportions
e.g. The emission of greenhouse gasses which lead to global
changes in temperatures
Natural processes can have global consequences
Accumulation of free oxygen in atmosphere 2000 Ma ago
Led to the ‘Oxygen Crises”
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
4. An Urbanizing World
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
4. An Urbanizing World
We are increasingly becoming an urban species
12%
2%
8%
Rural
21%
86%
1900
27%
38%
35%
2020
Cities < 1 mil
71%
Cities > 1mil
1950
23%
24%
53%
2000
ENV 101: Introduction to Environmental
Sciences - Lecture 2
Source: Fellman, J.D., Getis, A.,
Getis, J., 2003: Human Geography:
Landscapes of Human Activities,
McGraw Hill, Boston
2014
4. An Urbanizing World
Urban areas are growing
In 2008 for the first time more than half of the global
ଶ
population lived in cities. Expected to increase to by 2025
ଷ
Number of megacities (>10 mil people) increased from 2 in
1950 to 22 in 2005
Large numbers of cities are located along rivers and the
coast
Therefore agricultural areas associated with river
floodplains as well as wetlands along the coast are being
impinged upon
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
5. People and Nature
People and nature are intimately integrated
Our views of the environment (value system) determines how
we use the environment
The value of the environment based on eight justifications:
1.
2.
3.
4.
5.
6.
7.
8.
Utilitarian justification
Ecological justification
Aesthetic justification
Recreational justification
Moral justification
Cultural justification
Inspirational justification
Creative justification
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
5. People and Nature
Utilitarian Justification (materialistic)
Some aspect of the environment is valuable because it benefits
individuals economically or is directly necessary for human
survival.
e.g. Conserving wildlife due to the benefits associated with
tourism
Ecological Justification
An ecosystem is necessary for the survival of some species of
interest to us, or that the system itself provides some sort of
benefit
e.g. Conservation of mangrove ecosystems because they
harbour fish that are of economic importance
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
5. People and Nature
Aesthetic and Recreational Justification
Relates to our appreciation of the beauty of nature and our
desire to get out and enjoy it.
e.g. people who’d prefer to live in an area with wilderness
rather than in one without
Moral Justification
The belief that various aspects of the environment have the
right to exist and we have a moral obligation in this regard
e.g. United Nations General Assembly World Charter for
Nature (signed 1982) states thaat species have a moral right to
exist
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
5. People and Nature
Cultural Justification
Inspirational Justification
Different cultures have many of the same values, but also some
different values, with respect to the environment
e.g. Buddhist monks who will move disturbed earthworms
from a construction site vs. the killing of dolphins by Japanese
fisherman
Conservation based on its benefits to the human spirit (inner
selves)
Creative Justification
Nature as a source of creative inspiration
e.g. artists
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
6. Science
Knowing the scientific data and understanding its
implications
Precautionary Principle
When there is a threat of serious, perhaps even irreversible,
environmental damage, we should not wait for scientific proof
before taking precautionary steps to prevent potential harm to
the environment
Recognizes the need to evaluate all the scientific evidence we
have and to draw provisional conclusions while still continuing
the investigation
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
6. Science
Science is a process
Modern science does not deal with things that cannot be
tested by observation
Observations may be made by any of the 5 senses or by
instruments that measure beyond what we can sense
Results in conclusions, generalizations, scientific theories and
scientific laws
Qualitative data: non-numerical data (e.g. animal species name)
Quantitative data: numerical data (e.g. concentration of toxin)
Inferences are generalizations that arise from a set of
observations
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
6. Science
Variables
Dependant:
Independent:
A variable that changes in response to changes in an independent
variable .
In an observational study it is the variable that is believed by the
investigator to affect an outcome (dependant variable)
Reasoning approaches
Deductive reasoning:
Drawing a conclusion from initial definitions and assumptions by
means of logical reasoning
Inductive reasoning:
Drawing a general conclusion from a limited set of specific
observations
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014
6. Science
Models
Uncertainty
Accuracy
Deliberately simplified construct of nature
The extent to which the measurement agrees with an accepted
value
“refers to what we know”
Precision
The degree of exactness with which a measurement is made
“refers to how well me measure”
ENV 101: Introduction to Environmental
Sciences - Lecture 2
2014