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Transcript
Chapter 1: Environmental Science
A Global Perspective
“ All the flowers of all the tomorrows are in the seeds of today.”
Chinese Proverbs
Section 1.1: Understanding
our Environment
• What do you think of when you hear the
term “environment?” Some people think of
a beautiful scene, like mountains or streams
flowing through the wilderness.
• The environment is everything around us. It
includes the natural world as well as things
produced by humans. It is a complex web
of relationships that connect us with the
world we live in.
What is Environmental
Science?
• Environmental science is the study
of how humans interact with the
environment. Scientists work all
over the world to try to find
solutions to problems people
caused in the past to finding
sustainable alternatives for the
future.
The Goals of Environmental
Science
• One of the major goals of environmental science is
to understand and to solve environmental
problems. In order to accomplish this goal,
scientists study two main types of interactions
between humans and their environment. One
area of focus is on how we use natural resources,
such as water and plants. The other focuses on
how our actions alter our environment. In order to
study these interactions, they must gather and
analyze information from many different fields of
science.
Many Fields of Study
• Environmental science is an interdisciplinary
science (involves many fields of study.) One
important foundation of environmental science is
ecology. Ecology is the study of how living things
interact with each other and with their nonliving
environment. Ex: ecologists study the relationship
between bees and the plants they pollinate,
environmental scientists investigate how the
nesting behavior of bees is influenced by human
activities (planting of suburban landscaping).
• Other sciences also contribute to
environmental science. For example:
Chemistry helps us understand the nature
of pollutants; geology helps us model how
pollutants travel underground; botany and
zoology provides information needed to
preserve species; paleontologists study
fossils so we can see how Earth’s climate
has changed over time and predict how
future climate could possible affect future
life on Earth.
• Environmentalists may use information
from other sciences at any given time.
They also use information from the social
sciences (economics, law politics,
geography) to study human populations.
The social sciences help us to answer
questions about how people use the park
systems to how migration from rural to
urban areas may affect local
environments.
Scientists as Citizens,
Citizens as Scientists
• Studying the environment is vital to
maintaining a healthy and productive
society, thus environmental scientists are
asked to share the information they get
with the world.
• How do scientists know what to study?
• Oftentimes, nonscientists make observations
about the environment and inquire about them.
This prompts the environmental scientists to
investigate the issues. For example, middle
school students in Minnesota were concerned
about all the deformed frogs appearing in
Minnesota lakes. In Ohio, some high school
students in Dublin were curious about how the
endangered box turtles live and what factors
affected their nesting and hibernation sites.
After careful studies, the students were able to
present their findings to city planners in the hope
that the box turtle’s habitats would be protected.
Section 1.2: Our Environment
Through Time
• Environmental change is not a modern issue.
Wherever humans have hunted, grown food or
settled, they have changed the environment. (ex:
NYC now stands where Native Americans hunted
game and gathered food). This change has
occurred over the past 300 years. Moreover, the
21st century is a crucial time in human history; a
time to find solutions that will allow people all over
our planet to live in clean, healthy environments
and have all the resources they need for a good
life.
Hunter-Gatherers
• For most of history, people were huntergatherers (obtain food by collecting plants
and by hunting wild animals or
scavenging). Early group of huntergatherers were small and migrated to find
food that came ripe during certain times of
the year. Some people in New Guinea and
in the rain forests of South America are
considered hunter-gatherers even today.
• Early Native American tribes affected the
grassland areas by setting fire to the prairies in
order to prevent the growth of trees. They kept
the areas as open grasslands so they could
hunt bison. In addition, hunter-gatherers
groups probably helped to spread plant
species to areas where those plants did not
grow originally.
• Some large mammal species (giant sloths,
giant bison, mastodons, cave bears and sabertoothed cats) may have become extinct due to
the overhunting of the hunter-gatherers and
the rapid climate change in North America.
The Agricultural Revolution
• Eventually, hunter-gatherer groups starting
collecting plant seeds and started
domesticating some of the animals. The
practice of agriculture (the practice of
growing, breeding and caring for plants and
animals) started in many different parts of
the world as a result of these practices over
10,000 years ago. This “agricultural
revolution” had a dramatic impact on
human societies and their environment.
• It allowed human populations to grow at
unprecedented rates. Humans began to
concentrate in smaller areas, putting
increased pressure on local environments.
This agricultural revolution also changed
the food we eat. Most of the food we eat
today descended from wild plants. At
harvest, farmers would collect the seeds
from plants that produced the most
desirable traits and would plant them the
next year.
• Farming was replacing grasslands, forests
and wetlands. One of the earliest ways to
clear the land was to ‘slash and burn’ the
areas. This practice led to soil loss, floods
and water shortages. People were
practicing poor farming methods and left
the area unable to support growth. This
caused widespread environmental effects
when the soil became water-logged and
contaminated by salts.
The Industrial Revolution
• For almost 10,000 years the tools of
human societies were powered by humans
or animals. In the middle 1700’s, the
onset of the Industrial Revolution changed
this pattern. People moved from using
animal muscle to power the machinery to
using running water and fossil fuels (coal,
oil). This shift greatly increased the
efficiency of agriculture, industry and
transportation.
• Large scale production of goods became
less expensive than handmade goods,
farm machinery reduced the amount of
human labor on farms, and fewer people
grew their own food, thus increasing
populations in urban areas. Food and
goods were transported cheaply across
great distance by way of motorized
vehicles.
Improving Quality of Life
• The Industrial Revolution introduced many positive
changes. They made life easier for us but in
return, many of the problems that exist today are a
result of the Industrial Revolution. The invention
of the light bulbs improved our quality of life,
agricultural productivity increased, sanitation,
nutrition and medical care vastly improved. With
every improvement, environmental issues were
introduced (pollution, habitat loss).
• In the 1900’s, modern societies started using
artificial substances in place of raw animal and
plant products (ex: plastics, pesticides, fertilizers).
Spaceship Earth
• Earth has been compared to a ship traveling
through space that cannot dispose of waste or
take on new supplies as it travels. Earth is
essentially a ‘closed system.’ The only thing
entering is energy from the sun and the only
thing leaving is heat. There are problems
associated with this system. Some resources
are limited. As populations increase, those
resources will be used up. Waste is also
produced more quickly than we can dispose of it.
• Environmental problems can exist on
different levels: local (where to build
a landfill or arguing about the
importance of a rare bird or insect),
regional (drinking water that may be
affected by a polluted river) or global
(ozone-depleting chemicals released
in one part of the world will impact all
people in the world).
Population Growth: A Local
Pressure
• Environmental problems have been associated with
the agricultural revolution and the Industrial Revolution
as a result of the rapid growth of the human
population. The development of modern medicine and
sanitation also helped the increase in the human
population (quadrupled during the 20th century).
Producing enough food for such a large population has
environmental consequences (habitat destruction,
pesticide pollution). Scientists predict that the human
population will continue to increase, doubling in the
21st century, before it begins to stabilize.
What are Our Main
Environmental Problems
• There are unlimited numbers of
environmental problems facing us today;
however, almost all environmental
problems fall into one of three categories:
resource depletion, pollution and loss of
biodiversity.
Resource Depletion
• A resource is depleted when a large part
of it has been used up.
• Natural resource – any natural substance
that living things use (sunlight, air, water,
soil, minerals, plants, animals, forests,
fossil fuels)
• Natural resources can be classified as
renewable and nonrenewable.
Renewable Resources
• Renewable resources are resources that
are continually replaced (solar, trees, fish,
wind, air, water, soil, crops); but can be
depleted if used up faster than it can be
replaced, ex: trees.
Nonrenewable Resources
• . Nonrenewable resources are resources
that form at a much slower rate and
cannot be replaced (fossil fuels like oil,
natural gas); when they are used up, they
are gone.
• Resources are said to be depleted
when a large fraction of the resource
has been used up (ex: trees that are
harvested faster than they can grow
naturally in an area)
Pollution
• The Industrial Revolution began producing
wastes faster than the wastes could be
disposed of. These wastes accumulate in
the environment and cause pollution.
Pollution is an undesired change in air,
water, or soil that adversely affects the
health, survival or activities of humans or
other organisms. Most pollution is a result
of human activities.
• Two main types of pollutants:
biodegradable (can be broken down
by natural processes) pollutants and
non-biodegradable (cannot be broken
down by natural processes)
pollutants.
Biodegradable
• Biodegradable pollutant examples would
include human sewage or stacks of
newspapers. These items present a
problem when they accumulate faster than
they can be broken down.
Non-Biodegradable
• Non-biodegradable pollutant
examples would be mercury, lead and
some plastics because they do not
break down easily.
•
Loss of Biodiversity
• Biodiversity refers to the number and
variety of species that live in an area.
Only a fraction of the hundreds of millions
of species are alive today. All the others
are now extinct. Extinction is a natural
process, but during the course of history,
Earth has experienced mass extinctions
(250 million years ago, as much as 95% of
all species became extinct).
• Why should we be concerned with extinction of
species? We depend on other organisms for
food, for the oxygen we breathe and for many
other things. When a species becomes extinct,
it is gone forever. We have limited information
on the current rate of extinction among the
species alive today in comparison to organisms
in our past. Scientists believe that all species
have potential economic, ecological, scientific,
aesthetic and recreational value. So, they
believe it is in our best interest to preserve all
organisms.
• The Environment and Society
We need to consider human societies, how
they act and why they do what they do when
we think about environmental problems and
how could solve them. In order to do that,
we need to look at how a society uses
common resources. Ex: a neighborhood
park or the ocean. What do we need to do
in order to share those common resources?
Economics and the
Environment
• Economic influences influence how we
use resources.
Supply and Demand
• One of the basic economics is supply and
demand. The greater the demand, the
more it is worth. Ex: The relationship
between oil production and the price of oil.
If the supply of oil decreases, we have
three choices: pay the higher price, use
less oil or find new sources of energy.
Costs and Benefits
• A cost-benefit analysis balances the cost of the
action against the benefits one expects from it
and oftentimes, the results depend on who is
doing the analysis. To industry, the cost to
control air pollution may outweigh the benefits,
but to a nearby community, the benefits to have
clean air may be worth the high price.
Therefore, the consumer will have to determine
if they want to pay a higher price for a cleaner
product or seek out a cheaper alternative which
may not have the same environmental
safeguards.
Risk Assessment
• One of the costs of any action is the risk of
an undesirable outcome. In order to come
up with effective solutions to
environmental problems, the public must
perceive the risk accurately.
•
Developed and Developing
Countries
• The decisions and actions of all people in
the world affect our environment. But
unequal distribution of wealth and
resources around the world influences the
environmental problems that a society
faces and the choices it can make.
• United Nations classifies countries as
either:
• Developed – have high average incomes,
slower population growth, diverse
industrial economies, stronger social
support systems (ex: USA, Canada,
Japan, countries of western Europe)
• Developing – have lower average
incomes, simple and agriculture-based
economies, rapid population growth (ex:
India, Kenya)
• Some in-between countries are Mexico,
Brazil and Malaysia
Population and Consumption
• Almost all environmental problems can be
traced back to two root causes:
• Human population in some areas is
growing too quickly for the local
environment to support
• People are using up, wasting or polluting
many natural resources faster than they
can be renewed, replaced or cleaned-up
Local Population Pressures
• When populations grow too fast, there are not enough
natural resources for everyone to live healthy,
productive lives. In overpopulated areas, people
struggle for survival (forests are stripped bare, topsoil
is exhausted, animals are driven to extinction). People
suffer from starvation, malnutrition and disease.
Enough with all these things, populations tend to grow
more rapidly. Food production, education and job
creation cannot keep pace so each person gets fewer
resources. Safe drinking water, proper sanitation and
having access to enough food are constant struggles
in overpopulated areas.
Consumption Trends
• In wealthier parts of the world, life is better
than ever before. Pollution controls
improve every year, environmental
problems are being addressed, and
population is stabilizing or is growing
slowly. However, to support this way of
life, developed nations are using much
more of the world’s natural resources than
the developing countries.
• Developed countries are using about 75%
of the world’s resources even though they
only make up 20% of the world’s
population. This creates more waste and
pollution per person.
Ecological Footprints
• An ecological footprint is a calculation of
the amount of land and resources needed
to support one person from a particular
country. The ecological footprint of a
person in a developed country, on
average, is four times as large as the
footprint of a person in a developing
country.
Environmental Science in
Context
• Environmental problems are complex.
Simple solutions are and sometimes
cause more damage than the original
problem did.
Critical Thinking and the
Environment
• People on both sides of an environmental issue
may feel passionately about their cause.
Sometimes information gets distorted and
people are misled about the issues. Sometimes
information is used to make political points or is
misrepresented to support controversial
viewpoints. The media oftentimes
sensationalizes environmental issues or the
economic dimension of an environmental issue
is oversimplified. It is best if you make your own
decisions about environmental issues.
• You must use critical thinking skills to make
informed decisions:
• Be prepared to listen to many viewpoints. You
will hear many different reasons for the opinions
others form. Don’t react to their ideas without
trying to understand their viewpoint.
• Identify your own bias. How does it affect the
way you interpret the issue?
• Investigate the source of the information you
encounter. Question the conclusions that are
formed from the data.
• Gather all the information you can before
drawing a conclusion.
A Sustainable World
• Most people support one key goal of
environmental science: achieving sustainability
(the condition in which human needs are met in
such a way that a human population can survive
indefinitely).
• A sustainable world is not an unchanging world.
• Achieving sustainability requires everyone’s
participation: individual citizens, industry, and
government. All must cooperate and work
together.
Chapter 1, Section 5
• The word science comes from the Latin
verb, scire, meaning “to know.” However,
science is not just something you know,
but something you do.
The Experimental Method
• Most scientists make their discoveries
using the scientific method. This method
consists of a series of steps that scientists
use to identify and answer questions.
First step: Observing
• Someone notices, or observes something
and begins to ask questions. An
observation is a piece of information we
gather using our senses: sight, hearing,
smell, touch
•
Second step: Hypothesizing
and Predicting
• Observations will give us answers to
questions, but observation almost always
lead to more questions. To answer a
specific question, a scientist may form a
hypothesis (a testable explanation for an
observation.) A good hypothesis is more
than a guess; it should make logical sense
and follow from what you already know
about the situation.
Third Step: Experimenting
• Questions that arise from observations often cannot be
answered by making more observations. In this situation
scientists usually perform one or more experiments (a
procedure designed to test a hypothesis under controlled
conditions.)
• Experiments should be designed to pinpoint cause and
effect relationships. For this reason, good experiments
have two essential characteristics: a single variable
(factor of interest) is tested and control is used. To test
for one variable, scientists usually study two groups or
situations at a time. The variable being studied is the only
difference between the groups.
Fourth Step: Organizing and
Analyzing Data
• Keeping careful and accurate records is
extremely important in science. A scientist
cannot rely on experimental results that are
based on sloppy observations or incomplete
records. Information a scientist gathers
most often in numeric form and is called
data. Organizing this data into tables and
graphic illustrations helps scientists analyze
the data and explain the data clearly to
others.
Fifth Step: Drawing
Conclusions
• Scientists determine the results of their
experiments by analyzing their data and
comparing the outcome of their
experiment with their prediction. Ideally,
this comparison provides the scientists
with an obvious conclusion. But,
oftentimes, it is not obvious and they may
repeat their experiment.
•
Sixth Step: Communicating
Results
• Scientists publish their results to share
what they have learned with other
scientists. When they think their results
are important, they usually publish their
findings as a scientific article.
The Correlation Method
• Whenever possible, scientists will use
experiments to answer questions;
however, sometimes some questions
cannot be answered with experiments.
Ex: Does smoking cause lung cancer in
humans? (unethical and could injury)
What was Earth’s climate like 60 million
years ago? (we weren’t around then to
know)
• When you can’t answer a question with
experiments, then you would have to look
at reliable associations between two or
more events (correlations) to make
predictions. Ex: Relative width of a ring on
a tree is a good indicator of the amount of
rainfall the tree received in the previous
year. This method may be useful, but they
do not necessarily prove cause and effect
relationships between two variables.
Scientific Habits of Mind
• Scientists approach questions in many
different ways. Good scientists tend to
share several key ways of approaching
and thinking about things: curiosity,
skepticism, openness to new ideas,
intellectual honesty, imagination and
creativity.