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Prior to beginning work on this final paper, review all chapters of Bensel and Carbone’s Sustaining Our Planet text (2020).
In this paper, you will explore what a future sustainable world might look like, and in the process of doing so, extend your previous descriptions of selected terms and explain how they may play a role in aiding us in achieving environmental sustainability on a global scale.
The Journey to Sustainability
Imagine a future (probably a long time from now) in which human beings have achieved environmental sustainability on a global scale. That means that we as a species have figured out how to maintain a lifestyle that can go on indefinitely. Humans will exist in harmony with their environment, not needing more resources than can naturally be replenished. What would such a world be like? How might we get there from here?
In this final assignment, you will play the part of science-fiction writer, imagining and describing what a sustainable Earth, inhabited by humans, might look like in the distant future. You will need to provide examples throughout to support your descriptions. You should include all the terms that you have researched during Weeks 1 through 4 of this class, underlining each term as you include it. Be sure to expand on your terms and include other concepts that you learned in the course. Provide as detailed a picture as possible of how that future world might function on a day-to-day basis. In your paper, use grammar and spell-checking programs to insure clarity. Proofread carefully prior to submitting your work. Finally, you will submit the document to Waypoint.
Your paper will consist of seven paragraphs using the format below to address the elements with the assumption that environmental sustainability has been achieved:
Paragraph 1:
Describe how the human relationship to nature will be different from what it is at present.
Examine how humans will cope differently with the ways that natural phenomena like hurricanes affect lives.
Paragraph 2:
Explain what humans have done differently to enable biodiversity and ecosystems to function sustainably.
Differentiate between how humans will manage water resources (fresh water and ocean) in the sustainable future compared to how it is done now.
Paragraph 6:
Paragraph 7:
1
Understanding Environmental
Science and Sustainability
Purestock/Thinkstock
Learning Outcomes
After reading this chapter, you should be able to
•
•
•
•
•
•
Define environmental science.
Describe the importance of critical thinking, information literacy, and the scientific method.
Analyze the impact of palm oil plantations on biodiversity and the environment in Borneo.
Define the core concepts of natural capital and sustainability.
Define the core concepts of the environmental footprint and the Anthropocene.
Define the core concepts of uncertainty, scale, risk, and cost–benefit analysis.
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Why Study Environmental Science?
Section 1.1
1.1 Why Study Environmental Science?
Whether we realize it or not, almost every aspect of our daily lives is dependent on and connected to the natural world around us. We are a part of, and not separate from, that natural
world. The food we eat, the air we breathe, and the water we drink all originate from the natural world. Perhaps less obvious, the items we use every day—such as the fuel for our cars, the
clothes we wear, and our phones and electronic devices—all have their origins in the natural
world. At the same time, our everyday actions and use of these products—be it driving, eating, or throwing out the trash—all have an impact on this natural world on which we depend.
The study of environmental science encompasses all of these relationships. At its most basic,
environmental science is the study of how the natural world works, how we are affected by
the natural world, and how we in turn impact the natural world around us.
Our fundamental dependence on the natural world makes the study of environmental science
relevant to all of us. Environmental issues—including deforestation, ozone depletion, water
pollution, and climate change—affect us all. These issues are also in the news now more than
ever, and they are often at the center of heated political debates. Acquiring an understanding
of the basic science behind these debates is thus an important part of becoming an educated
citizen and forming your own opinion of the issues. And while you may not go on to make a
career in environmental science, you will likely find that this discipline intersects with your
major or field of study in some way.
The goal of this book is to help you understand the basics of environmental science so that
you can further explore and research environmental issues that interest and affect you
directly. Because environmental issues can be so complex, developing solutions requires a
solid understanding of policy and scientific concepts. In this book, we will apply natural science and social science concepts to the study of environmental issues that are in the news
every day. The hope is that you—armed with the knowledge, perspectives, and up-to-date
information provided in this book—will begin to form your own, informed opinions on these
subjects. Ideally, you will also develop ideas about how you as an individual or society more
broadly can take action to address some of the most pressing environmental challenges facing the world today. Ultimately, this book aims to empower you as a student both to grasp the
environmental challenges facing the world and to do something about them.
Outline of the Book
Much of the rest of this chapter, and most of Chapter 2, focuses on introducing you to concepts
and ways of thinking that are essential to the study of environmental science and that will
appear repeatedly throughout the rest of the book. You can think of these chapters as laying a
foundation for your study of specific environmental issues in subsequent chapters. Just as you
would not expect to be able to cook or repair cars without the right tools and basic knowledge
of those activities, it would be difficult to study environmental issues without the information
provided in these first two chapters.
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Why Study Environmental Science?
danielvfung/iStock/Getty Images Plus
Section 1.1
With a strong foundation in place, we’ll
move to the study of human population and
material consumption in Chapter 3. Virtually all of the environmental challenges
we face are thanks to the growing number
of people on the planet and high rates of
material consumption among some of those
people. In this way, we could say that human
population growth and material consumption are the fundamental drivers of environmental change in the world today.
Chapters 4 through 9 focus on specific environmental issues and challenges: management of agricultural and forest resources,
freshwater resources, oceanic resources,
energy resources, atmosphere and climate,
and waste. These chapters involve a heavy emphasis on negative news and challenges, so
Chapter 10 aims to end the book on a more upbeat note. While it’s true that we face enormous
and complicated worldwide environmental problems, it’s also true that governments, nongovernmental organizations (NGOs), corporations, small companies, schools and universities, and individual citizens are taking steps to address and reverse those challenges. We will
examine their stories in hopes of inspiring positive change in our own lives.
The biggest driver of environmental change in
today’s world is human population growth and
rates of consumption, which have increased
exponentially in the past 200 years.
Key Definitions in Environmental Science
While we may hear or use the words environment, environmentalism, and environmental science quite often, we might not always appreciate what they mean and how they are used in
the study of environmental issues. At its most basic level, the environment is everything that
surrounds you. This includes all living things (such as animals, plants, and other people), as
well as all nonliving things (such as water, rocks, air, and sunlight). A more scientific definition
of the environment would be all physical, chemical, and biological factors and processes that
affect an organism.
Based on that definition, it should be clear that we are all a part of the environment rather
than apart from it. In fact, one major theme of this book is that, despite all the technological
gadgets and scientific advances that attract our attention, we are all fundamentally dependent on the environment for our well-being and survival. The task of sustaining our agricultural resources, forests, water sources, oceans, atmosphere, and climate is not just about
“caring” for this creature or “saving” that endangered animal. It’s also about saving ourselves
and ensuring that we and generations to come can breathe clean air, drink clean water, and
live under relatively stable and benign climate conditions.
Because the environment by definition is basically everything, environmental science is a
complex and interdisciplinary field of study. Environmental science draws together knowledge and concepts from many disciplines—ecology, biology, chemistry, geology, atmospheric
science, physics, economics, political science, and other fields—to understand both how we
are impacting the environment and what can be done to lessen that impact.
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Thinking Critically About Environmental Science
Section 1.2
Note that there is a difference between environmental science and environmentalism. Environmentalism is a social and political movement committed to protecting the natural world.
While many environmental scientists likely consider themselves environmentalists, as scientists they adopt a more objective approach to the issues they study. This approach is based in
large part on the use of the scientific method, an approach to research based on observation,
data collection, hypothesis testing, and experimentation. As a student, you are not required
or expected to become an environmentalist, but as an educated citizen, you should learn to
recognize the critical role played by the scientific method in forming our understanding of the
environment and the environmental challenges we face. Such an understanding of the scientific method will help you develop critical-thinking skills and enable you to weigh competing
claims and arguments about environmental issues.
1.2 Thinking Critically About Environmental Science
Many environmental scientists see their
work as largely nonpolitical and noncontroversial. They are attempting to understand
how a particular piece of the environment
or system—a stream, a wetland, a patch of
forest—functions and what might happen
to that system in the wake of pollution or
some other environmental disturbance.
However, because the findings of this environmental research are often used in crafting and implementing environmental policy, environmental science and debates over
environmental issues can become highly
contentious and political.
patriziomartorana/iStock/Getty Images Plus
Environmental scientists aim to understand
how different elements of the environment
function and how they change in response to
other factors, such as pollution.
Take, for example, the topic of global climate change (which will be covered in more
detail in Chapter 8). Thousands of environmental scientists are engaged in research that is
in some way related to the subject of climate change. Some scientists study how combustion of fossil fuels or other human activities add greenhouse gases to the atmosphere, others
how these gases change the Earth’s energy balance and climate systems, and still others how
changes to the climate are affecting trees, animals, and other living organisms.
The majority of these scientists would probably not see their work as contentious or political.
They are instead usually motivated by scientific curiosity and a desire to pursue knowledge.
However, because the sum of these thousands of research efforts points with overwhelming
confidence to the realities of global climate change, and because addressing climate change
will require changes to all sorts of economic and social behaviors, the efforts of these environmental scientists can become politicized. Because of this politicization, it’s important to
understand the concepts of critical thinking, information literacy, and the scientific method.
Careful application of these approaches to your own study of the environment will help you
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Thinking Critically About Environmental Science
Section 1.2
develop informed opinions on many issues and help you avoid falling for arguments that are
based on opinion and personal belief rather than grounded in facts and scientific evidence.
Critical Thinking and Information Literacy
Critical thinking is the objective analysis and evaluation of an issue to form a judgment.
In this case, the key term is objective analysis—in other words, analysis that is not based
on personal opinion or belief. For example, one of this book’s authors had a student who,
while hiking, saw a number of dead birds on the ground near the base of some wind turbines.
The student later expressed a conviction that wind power was bad for the environment and
should not be used. While there are legitimate reasons to be concerned about the effect of
wind turbines on bird (and bat) mortality, this student should also consider what the environmental impact of other forms of electricity production are. In the authors’ region of the
country (Pennsylvania), much of the electricity is produced by burning coal. A better example
of objective analysis would be a comparison of the environmental impacts of coal mining and
coal burning (including the impact on birds and bats) to the impact of wind turbines.
As you engage with the material in this book, and as you do your own research and form your
own opinions about environmental issues, keep the following principles of critical thinking
in mind:
•
•
•
•
•
Evaluate the basis for a particular conclusion. What evidence is being presented to
support a claim or an argument, and how was that evidence collected?
Keep an open mind. Attempt to gather information from a variety of perspectives
before forming a final opinion.
Be skeptical. While keeping an open mind, ask yourself where information is coming
from and how it was developed.
Consider possible biases, including your own. Most scientists strive mightily to avoid
the introduction of bias into their work, and the scientific method (described in
more detail later) helps them do that.
Distinguish between facts and values or opinions. For example, it is a fact that atmospheric concentrations of the greenhouse gas carbon dioxide now exceed 400 parts
per million (ppm) compared to levels of roughly 280 ppm at the start of the Industrial Revolution. However, it’s an opinion or value statement to say that the use of
all fossil fuels should be halted immediately to prevent further increases in carbon
dioxide concentrations.
A key part of establishing and utilizing critical-thinking skills is to develop what’s often
referred to as information literacy. Information literacy is the ability to know when information is needed and the ability to identify, locate, evaluate, and effectively use that information
to address an issue. For our purposes, the most important of these abilities will be locating
and evaluating information. The past two decades have witnessed an explosion of information and information sources, and our ability to access that information is becoming easier
every day. However, our ability to know where to look for reliable information and to evaluate
that information for reliability and usefulness has not kept pace. For example, there are thousands of sources of information on the topic of climate change. Who should you believe? Who
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Thinking Critically About Environmental Science
Section 1.2
can you trust? We can see how critical-thinking skills are needed for information literacy and
how information literacy is required for critical thinking. As you read this book and explore
on your own the environmental topics and issues that interest you, ask yourself where information is coming from, how it was gathered, and how reliable it might be. The Apply Your
Knowledge: Is This Information Reliable? feature box presents one quick opportunity to test
your critical-thinking skills.
A less appreciated but nevertheless important skill for environmental analysis and problem
solving is creative thinking. As scientists examine an environmental issue and ponder its
possible causes and consequences, it helps if they can think creatively and with an open mind,
as opposed to being locked into one way of looking at the world. Environmental scientists
also tap into creative thinking to design effective field experiments that help them better
understand the workings of nature. And as we’ll see throughout this book, it will take creative
thinking and even imagination to develop alternative approaches to meeting our food, water,
energy, and other resource needs in ways that do not destroy the environment.
Apply Your Knowledge: Is This Information Reliable?
Evaluating the quality and reliability of information can be a difficult task, especially when
we are considering resources found on the Internet. We live in a world in which opinions are
sometimes presented as the unbiased truth, and pretty much anyone with a computer can
create a convincing website that is accessible to the entire world.
To highlight some of these challenges, let us explore a website called Save the Pacific
Northwest Tree Octopus. At first, the prospect of a tree-dwelling octopus might seem
absurd, but nature often surprises us. There are birds that can swim and fish that can fly, so
why not an octopus that climbs trees? If you read the article, you might also notice that the
information presented is fairly detailed. The author provides a Latin name for this creature,
along with measurements that describe tree octopus physiology. There are even photographs
and links to additional resources, suggesting that others have documented these creatures in
the past.
Despite the website’s flashy appearance, it is a total hoax. There is no such thing as a tree
octopus, and if we take a closer look at the website, we can see some warning signs that call
its information into question. Take a moment to explore the Save the Pacific Northwest Tree
Octopus website on your own, and see if you can find any red flags indicating that the article
is unreliable.
(continued)
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Thinking Critically About Environmental Science
Section 1.2
Apply Your Knowledge: Is This Information Reliable?
(continued)
One characteristic of trustworthy information is that it comes from a reputable author
or organization. For example, information from a government agency, an institution of
higher education, or a peer-reviewed journal is often considered to be more reliable than
information from a personal blog. Reliable resources will also provide access to author
biographies so that you can tell if the author is an expert on the subject matter. If you look
at the author information at the bottom of the tree octopus website, you will notice that the
author description is downright silly. There is no indication that the person has any training
related to the subject matter.
Reliable resources also need to be fact-checked or backed up with supporting information
that is usually identified using links and citations. This website appears to have active links to
other resources, but if you follow these links, you will notice that they take you to other hoax
websites or to sites that have no mention of tree octopuses.
Finally, reliable sources will be clear about whether their goal is to inform you with factual
information or to convince you of a particular argument. A close reading of the material
can often tell you if an unreliable resource is trying to convince you of an opinion while
appearing to present objective facts. Consider the following sentence from the tree octopus
website:
Tree octopuses became prized by the fashion industry as ornamental decorations for
hats, leading greedy trappers to wipe out whole populations to feed the vanity of the
fashionable rich. (Zapato, n.d., para. 8)
Phrases like “greedy trappers” and “vanity of the fashionable rich” suggest that the author
is making judgments about certain actions and groups of people. This is not what we would
expect from a well-written article that is intended to present factual information.
Now, take a moment to explore another web resource titled “Discovery of the First
Endemic Tree-Climbing Crab.” Once again, the topic sounds bizarre, but if we look closely,
the information seems much more trustworthy. The article was produced by an academic
institution. The language used in the article appears to be unbiased, and the information can
be easily fact-checked using the peer-reviewed journal articles and academic websites that
are referenced at the end. This article appears to be a source of reliable information.
Save the Pacific Northwest Tree Octopus is a silly example of “bad” information, but the
critical-thinking skills we used to evaluate this source can be applied to everything that
we read, hear, and watch. If we approach media critically, we’ll be able to recognize the
trustworthy information that helps us make better policies and decisions. In your future
studies, look for information that is from a trusted source. Look for information that is
backed up by quality research and journalism. Finally, look for information that is attempting
to inform rather than persuade (unless you are researching opinions, of course).
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Thinking Critically About Environmental Science
Section 1.2
The Scientific Method
The use of the scientific method is one way that environmental scientists seek to improve the
reliability, usefulness, and relevance of their research. The scientific method is an approach
whereby scientists observe, test, and draw conclusions about the world around us in a systematic manner, rather than simply stating opinion. The scientific method consists of a series
of five steps, as illustrated in Figure 1.1.
Figure 1.1: The scientific method
The scientific method is a five-step model used to observe, test, and draw conclusions scientifically.
1. Make observations
2. Ask questions
3. Formulate hypothesis
4. Make predictions
5. Test predictions
Scenario A: Test supports
hypothesis. Additional predictions
can be made and tested.
Scenario B: Test does not
support hypothesis. Formulate
new hypothesis and retest.
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Thinking Critically About Environmental Science
Section 1.2
Scientists begin with simple observations of the world around us. They then form questions
based on those observations. For example, environmental scientists might observe the death
and decline of numerous trees alongside a major highway and naturally wonder what is causing this to happen. This leads to the third step, the formulation of a hypothesis or hypotheses
that might explain the trees’ death. Hypotheses can be thought of as a first guess or “hunch”
about something, and they help scientists formulate predictions, specific statements that can
be tested. In this case, the scientists might form a hypothesis that the trees are dying because
of road salt running off the highway in the winter or because of an herbicide sprayed to control weeds on the side of the highway. Based on these guesses, they can take the fourth step
in the scientific method and develop specific and testable predictions about how much road
salt or herbicide needs to be applied to bring about the same levels of tree death and decline
they have observed in nature.
All of these steps lead up to the final step of testing the predictions. To clearly determine what
might be killing the trees, scientists devise experiments that attempt to hold conditions constant and then change one variable at a time. In this case, scientists might identify four similar
small groves of trees that show no sign of stress or tree death. They might then expose one
area to road salt, another to herbicide, and a third to both road salt and herbicide, while the
fourth area is left alone. (Apply Your Knowledge: How Does Road Salt Affect Trees? shows how
scientists might record their data.)
Note that regardless of the outcome of these experiments, scientists will typically still do two
additional things. First, if the road salt or herbicide appeared to have some impact on the
trees, the scientists might refine their predictions to gain a better understanding of why this
is happening. This might include adjusting the levels of road salt or herbicide to see if they can
better determine at what levels these applications become toxic. If the trees were not affected
by the road salt and herbicide, the scientists would be forced to revise their hypotheses or
form new ones. Second, scientists typically seek to share their results with others, usually
by presenting their research at scientific conferences and publishing articles in professional
journals. These presentations and papers are subject to analysis and scrutiny by other scientists, a process known as peer review. Scientists also have to explain the methods used in their
research so that other scientists can run the same experiments, a process known as replication. These two aspects of scientific research, peer review and replication, help ensure the
accuracy and legitimacy of the work.
It’s important to recognize just how the scientific method can shield scientists from claims of
bias. Scientists don’t really set out to “prove” anything; instead, they observe, ask questions,
hypothesize, predict, test, and usually repeat. Politicians’ demands for scientific “proof” are
therefore problematic. Environmental policy should be informed by the best science available, as well as other issues such as ethical concerns, economic impacts, and risks involved.
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Thinking Critically About Environmental Science
Section 1.2
Apply Your Knowledge: How Does Road Salt Affect Trees?
Environmental scientists make use of many different types of graphs to summarize and
present the data they gather in their research. Graphs help in taking enormous amounts of
data and information and presenting them in a way that tells a story or makes an argument.
Your ability to understand and interpret graphs will be an important part of reading this
book and learning environmental science.
Consider the following figures, which show possible results from the road salt/herbicide
example used in the discussion of the scientific method. Figures 1.2 and 1.3 report basically
the same information on tree death and decline from the experiment in different ways.
Figure 1.2 portrays the number of trees that died in the different plots of the experiment over
time. Figure 1.3 presents overall tree deaths by plot type at the end of the experiment.
Figure 1.2: Line graph showing tree damage
This graph shows tree damage over time.
Number of trees showing stress or damage
12
11
Road salt and herbicide
10
Road salt
9
Herbicide
8
No application
7
6
5
4
3
2
1
0
Week 1
Week 2
Week 3
Week 4
(continued)
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Thinking Critically About Environmental Science
Section 1.2
Apply Your Knowledge: How Does Road Salt Affect Trees?
(continued)
Figure 1.3: Bar graph showing tree damage
This graph shows tree damage by plot type.
Number of trees showing stress or damage
12
11
10
9
8
7
6
5
4
3
2
1
0
Road salt
and herbicide
Road salt
Herbicide
No application
Based on the data presented from this experiment, it appears that road salt might be the
biggest contributor to tree mortality. Imagine then that the scientists conducted a second
experiment with four plots of trees in which they applied different amounts of road salt and
measured tree mortality over a 4-week period. Table 1.1 gives information on the amount of
road salt applied to each of the four plots and the corresponding tree mortality. Try plotting
these numbers on a piece of paper. Draw a straight line that comes closest to connecting each
of the four points on the graph. What does the shape and direction of this line tell you about
the relationship between road salt application and tree mortality?
Table 1.1: Amount of road salt and tree damage
Road salt application (metric tons/hectare)
Tree damage (dead trees per plot)
Plot 1 (1 metric ton/hectare)
2
Plot 3 (3 metric tons/hectare)
8
Plot 2 (2 metric tons/hectare)
Plot 4 (4 metric tons/hectare)
5
12
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Case Study: Palm Oil Production and Deforestation in Borneo
Section 1.3
1.3 Case Study: Palm Oil Production and Deforestation
in Borneo
Environmental scientists, as well as other natural and social scientists, frequently make use
of “case studies” to illustrate important points or concepts. In some ways, case studies are
simply formalized stories about a specific place, person, group, or other thing. The case study
presented here will help illustrate concepts and terms such as environment and environmental science and demonstrate how environmental scientists make use of critical-thinking skills
and the scientific method in their work. This case study will also be used to explain some of
the foundational concepts introduced later in this chapter and in Chapter 2.
About Borneo
The island of Borneo straddles the equator in Southeast Asia and is the third largest island in
the world and the largest island in Asia. The island is divided between Indonesia, Malaysia,
and Brunei, with Indonesia controlling roughly 73% of Borneo’s land area, Malaysia 26%, and
tiny Brunei just 1% (see Figure 1.4).
Figure 1.4: Borneo
Located in Southeast Asia, Borneo is known for its high rates of biodiversity, but its rain forests are in
decline due to deforestation
BORNEO
Adapted from PeterHermesFurian/iStock/Getty Images Plus
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Case Study: Palm Oil Production and Deforestation in Borneo
Section 1.3
Until very recently, Borneo was sparsely populated, and much of the island was covered in
dense tropical rain forests. Because of this, Borneo is known for its extremely high rates of
biological diversity, or biodiversity—the variety of life and organisms in a specific ecosystem. That variety can be measured by considering the number of species found in a particular area. Species are groups of organisms that share certain characteristics, interbreed, and
produce fertile offspring. In addition to having an incredibly high number of species overall,
Borneo is also known for having a large number of endemic species—plants and animals
that exist in only one specific geographic region. There are dozens of endemic mammal species (such as the proboscis monkey and pygmy elephant), hundreds of endemic birds, and
thousands of endemic plant species in Borneo. Rates of biodiversity are so high in Borneo that
scientists have identified over 20,000 types of insect species in one small national park alone
(Shoumatoff, 2017).
The Problem
Beginning roughly 50 years ago, Borneo’s rain forests began to decline in dramatic fashion.
Actions such as logging trees for timber, clearing land for small-scale agriculture, and burning large tracts of forest to clear land for palm oil plantations have reduced the island’s forest
cover from 75% in the mid-1980s to less than 50% today. Current rates of deforestation—
clearing of forest areas—in Borneo are estimated to be 1.3 million hectares (over 3 million
acres) a year (World Wide Fund for Nature, 2019).
Among the major drivers of deforestation in Borneo, conversion of rain forests to palm oil
plantations is currently the most significant. Palm oil is derived from the nuts of the oil palm
tree and is now the second most important oil used in consumer products after petroleum.
Palm oil is a $50-billion-a-year industry (Shoumatoff, 2017), and it is used in a vast array
of household and consumer products, including cooking oil, snack foods, chocolate, cosmetics (such as lipstick), toothpaste, ramen noodles, shampoo, ice cream, cookies, and soap. It’s
estimated that palm oil is an ingredient in roughly half of all packaged products sold in modern supermarkets. Millions and millions of acres of rain forest have been cut and burned in
Borneo to make way for palm oil plantations, and this deforestation continues today. Because
most of us probably consume products made with palm oil, we are all in some way connected
to this problem.
pxhidalgo/iStock/Getty Images Plus
Laszlo Mates/iStock/Getty Images Plus
Much of Borneo’s tropical rain forest has been razed for palm oil plantations.
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Case Study: Palm Oil Production and Deforestation in Borneo
Section 1.3
The Impact
Conversion of Borneo’s rain forests to palm oil plantations may result in a number of serious
environmental and social problems. Many different types of wildlife depend on forests as
their natural habitat—the place or set of conditions an organism depends on for survival—
so deforestation leads to high rates of biodiversity loss and extinction, or the total loss of
a species. Cutting up rain forests also results in habitat loss, driving wildlife species into
smaller and smaller areas for survival. Loss of tree cover leads to increased flooding as heavy
tropical rains run off cleared hillsides instead of being absorbed by dense forest soils and
vegetation. This flooding also results in water shortages later on, since rainwater rushes to
rivers and the sea instead of replenishing local groundwater supplies. Lastly, burning of forests worsens climate change in two ways. First, the combustion of trees and other vegetation
pours millions of tons of carbon dioxide, a greenhouse gas, into the atmosphere. We’ll see in
Chapter 8 that increased greenhouse gas concentrations are resulting in global warming and
climate change. Second, the ability of those forests to absorb and store vast amounts of carbon from the atmosphere is lost.
Borneo’s extremely high rates of biodiversity, combined with the widespread deforestation of
the past few decades, make this island one of the world’s most important biodiversity hotspots.
A biodiversity hotspot is a region that both has high rates of biodiversity and is experiencing
significant environmental destruction. There are roughly 25 regions of the world that scientists have labeled as biodiversity hotspots. Scientists hope that by calling attention to these
regions and the endangered species—species at risk of extinction—that live there, they can
encourage governments, businesses, and private citizens to take action to address the problem before it is too late.
A Scientific Approach
Let’s consider how environmental scientists approach the study of an issue like palm oil production and deforestation in Borneo. First, it’s clear that our own understanding of what’s
happening in Borneo is the result of interdisciplinary research by many different kinds of
scientists and experts. Botanists, entomologists, and ornithologists research Borneo’s plants,
insects, and bird species, respectively. Wildlife biologists examine how deforestation is driving endangered species into smaller geographic areas. Hydrologists seek to understand the
impacts of deforestation on flooding and water supplies. Atmospheric scientists and soil scientists attempt to understand how deforestation impacts carbon storage and greenhouse gas
emissions from forest soils. Remote sensing specialists use satellite imagery to measure rates
of deforestation over time. Environmental health specialists study the impact of pesticide
and herbicide spraying of palm oil plantations on local human populations. And social scientists—economists, anthropologists, policy experts—study what’s driving deforestation, how
local human populations are responding, and what might be done in terms of policies and
economic incentives to address this challenge.
All of these scientists and experts apply critical-thinking and information-literacy skills to
their work. Most of them also make regular use of the scientific method in defining and carrying out research in their specific areas. For example, a botanist (plant expert) or ornithologist
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Core Theme: Sustaining Our Natural Resources
Section 1.4
(bird expert) might conduct research to measure the number and variety of plant and bird
species in intact forest areas as well as in forest areas that have been fragmented or disturbed.
Hydrologists (water experts) might study rates of water flow and water quality in different
river basins that are characterized by different levels of deforestation. These and other scientists working in a setting such as Borneo might care deeply about wildlife and feel terrible
about the environmental destruction they see, but they still approach their work in an objective and scientific manner.
1.4 Core Theme: Sustaining Our Natural Resources
The remainder of this chapter will focus on introducing you to a series of concepts and terms
that will be important as we explore specific environmental issues in subsequent chapters.
This foundation of knowledge will provide you with a vocabulary and way of thinking that
will help frame the rest of the book. As we discuss these concepts and terms, we will return to
the example of deforestation in Borneo to better understand their meaning. We’ll start with
the concepts of natural capital and sustainable development. These concepts lie at the core of
environmental scientists’ work, which often focuses on supporting the environment that we
all depend on and are all a part of.
Natural Capital and Ecosystem Services
Most of us have experienced a power outage,
an Internet outage, a road closure, or disruption in some service that we depend on in
our day-to-day lives. Such disruptions often
remind us of the basic infrastructure (such
as the power supply, the water supply, and
functioning roads) we depend on but usually
take for granted. In much the same way, and
to an even greater degree, we depend on the
natural world, the environment, and the natural systems that make up the environment for
our well-being and survival. Yet we seldom if
ever really think about that dependence and
what it means to our quality of life.
staticnak1983/E+/Getty Images
Ecosystems, derived from the Greek word for
home, provide us with areas for recreation,
spirituality, and joy.
Environmental scientists refer to this natural
infrastructure as natural capital. Natural capital can be defined as natural assets such as
trees, soils, streams, oceans, and the atmosphere. Like other forms of infrastructure, because
natural capital is all around us, we seldom give it much thought. Take, for example, the tropical rain forests of Borneo. Managed properly, these forests could yield a steady supply of timber, fruit, and other nontimber forest products such as rubber, medicinal plants, and building
materials like bamboo. These forests could also be a destination for ecotourism, tourism that
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Core Theme: Sustaining Our Natural Resources
Section 1.4
focuses on natural environments in an effort to help conserve an area and support the local
economy.
But understanding natural capital requires us to think more broadly than just in terms of
resources. Even as valuable as all of these things—timber, nontimber products, and tourism—might be, they only scratch the surface of the real value humans derive from such ecosystems. These stocks of natural capital, through their normal functioning, generate a flow
of life-sustaining ecosystem services that are absolutely essential for human survival (see
Figure 1.5). We’ll learn more about what ecosystems are in Chapter 2, but for now think of
them as complex systems made up of both living organisms and nonliving components. For
example, forests help purify air and water supplies, help prevent extremes of drought and
floods, provide space and conditions for the decomposition of wastes, provide habitat for pollinating insects and birds that are essential to agriculture, and play a critical role in storing
carbon and maintaining regional and global climate systems. Even this list is incomplete, and
this is only describing the services of one ecosystem. Other systems—grasslands, wetlands,
coral reefs, tundra, deserts, coastal systems, and open oceans—all provide their own ecosystem services that are essential to our survival.
Figure 1.5: Natural capital and ecosystem services
Stocks of natural capital are all around us and generate a flow of ecosystem services and value for
humans.
Natural capital stocks
Ecosystem services
Yield
CO2
O2
Yield
Adapted from “What Is Natural Capital?” by Natural Capital Coalition, n.d. (https://naturalcapitalcoalition.org/natural-capital-2).
A simple analogy would be to think of a home. Earth’s natural systems, like a home, take care of
climate control, air purification, the provisioning of food and water, and waste disposal and purification. They provide us spaces for recreation, spiritual growth, and moments of joy. It’s perhaps
no accident that the prefix eco– in ecosystem is derived from the Greek word oikos, or “home.”
In the chapters ahead, try to apply this analogy and the concepts of natural capital and ecosystem services to issues of soil depletion, deforestation, water and air pollution, overfishing,
climate change, ozone depletion, and toxic waste dumping. What are we doing to our home
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Core Theme: Sustaining Our Natural Resources
Section 1.4
when we create these problems? How might our actions be destroying natural capital and
undermining the very systems we all depend on? What would alternative approaches, those
focused on sustaining natural capital, look like?
Sustainability and Sustainable Development
The concepts of sustainability and sustainable development come up a lot in discussions of the
environment. But what do they really mean? At a basic level, and applied to issues of the environment, sustainability is the maintenance of natural systems and an ecological balance.
Sustainable development brings human and economic needs into the picture and is the
achievement of economic objectives without the depletion or destruction of natural systems.
In other words, sustainability and sustainable development suggest a balancing act between
meeting the needs of humans and maintaining the integrity of our natural environment.
Understanding the concepts of natural capital and ecosystem services means understanding
that sustainable development is the only way forward for the human species. Development
that is not sustainable, that destroys or depletes natural systems and natural capital, will only
undermine the basic ecological systems that we all depend on. In this sense, it should be clear
that viewing economic progress and environmental protection as competing goals is ultimately foolish and misguided. We cannot sustain economic progress and human well-being
if, at the same time, we are undermining and destroying the natural infrastructure that makes
such progress possible.
Unfortunately, much economic activity and economic development we see around the world
today is unsustainable. Think of a business or a household trying to make ends meet. That
business or household might be able to balance its books month to month by selling off equipment or other assets, but eventually this approach is not sustainable. Likewise, much of the
economic progress in recent decades has been based on liquidating, or using up, natural capital such as oil, coal, soils, forests, fisheries, mineral stocks, and other resources. This economic
progress has also generated massive amounts of pollution and waste products, and this pollution is overwhelming the natural ability of many ecosystems to provide air and water purification services. In other words, our current economic progress and economic systems do
not meet the definition of sustainability and instead result in natural capital depletion and
destruction.
In Borneo, logging for timber, clearing forests for agriculture, and widespread burning of
forests to make way for palm oil plantations represent one approach to economic development—but in most cases one that is not sustainable. Overexploitation of timber resources
and logging faster than the rate of tree regrowth ultimately reduce the productivity of that
forest and make it less valuable over time. They also increase the risk of flooding, reduce
water supply, and diminish water quality, all outcomes that actually reduce quality of life and
impose costs on society. Likewise, conversion of tropical forests in Borneo to palm oil plantations may result in a short-term boost to the local economy and provide some employment
opportunities. However, plantation establishment also results in flooding, water contamination, loss of forest products, and other problems that might very well offset any positive
economic gains.
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Core Theme: Examining Our Impact
Section 1.5
In this way we can see how the concepts of natural capital and sustainability are tightly linked.
Sustainable economic development does not depend on the destruction and liquidation of
natural systems and natural capital, and therefore it does not undermine people’s future
ability to enjoy the services and benefits of these systems. Instead, sustainability means that
we strive to meet our needs in ways that maintain stocks of natural capital and the ecological integrity of natural systems. Think about this in the chapters ahead as we examine the
environmental and ecological impacts of current approaches to food production, energy use,
waste management, and other activities. Also try to imagine what a sustainable approach to
these activities might look like.
1.5 Core Theme: Examining Our Impact
Now that we know what we are trying to sustain—natural capital—how do we know if we are
actually doing so? What are some indicators that can be used to determine if our economic
activities have gone too far and are actually undermining our long-term prospects? This section will introduce two concepts, the environmental footprint and the Anthropocene, that
suggest we are overexploiting natural capital on a worldwide basis and undermining longterm prospects for sustainability.
The Environmental Footprint
Few of us give much thought to the impact we have on the environment. If we do think about
our impact, we tend to do so mainly in terms of our immediate surroundings. In reality, our
lifestyle and consumption patterns often have far-reaching effects on many parts of the environment in ways that are difficult for us even to imagine. For example, how often do you think
about where your water or food comes from? Many of us rely on municipal water systems that
might involve pumping water hundreds of miles and running it through a series of filtration
and purification systems before distributing it to thousands of households and businesses.
Almost all of us depend on commercial food systems that distribute food from all over the
world using trucks, boats, trains, and even planes. When you flip a light switch or flush a toilet, do you think about where that electricity comes from or where that waste is going? All of
these services are complex systems that require significant energy and resources, and these
systems often have wide-ranging environmental impacts.
Because so many of our activities and consumption patterns have environmental and ecological impacts that are invisible to us—out of sight, out of mind—environmental scientists have
developed the concept of an environmental or ecological footprint. An environmental footprint is a measure of how much land area and water is necessary to support an individual or a
group of people (see Figure 1.6). For example, how much land and water is needed to grow the
food you eat or the timber, paper, and forest products you use? How big of an area is needed
to effectively absorb and convert the liquid, solid, and gaseous wastes that you produce every
day? Because we consume resources in different ways and live different lifestyles, individuals
can have different environmental footprints. In terms of diet, for example, it takes more land
and water to produce meat than an equivalent amount of grain or vegetables. Therefore, a
person with a heavily meat-based diet is likely to have a larger environmental footprint than
someone who eats less meat or is vegetarian.
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Core Theme: Examining Our Impact
Section 1.5
Figure 1.6: Environmental footprint
If we were to illustrate the United States’ environmental footprint, it might look like this. How much land
and water does your lifestyle require?
Carbon footprint
(energy use)
Built-up land
Cropland
Forest products
Pasture/livestock
Fisheries
Adapted from “WWF Report: Global Wildlife Populations Could Drop by Almost 70% by 2020,” by WWF, 2016 (https://www.wwf.org.hk
/en/news/press_release/?uNewsID=16820).
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Core Theme: Examining Our Impact
Section 1.5
Individual environmental footprints can be summed to determine the overall footprint of a
larger group of people, such as a city or an entire country. These cumulative environmental
footprints can be measured against the actual amount of land and water resources available
to that population in order to determine whether current consumption patterns are sustainable. In other words, the environmental footprint of a given population is a measure of its
natural capital use, and by comparing natural capital utilization to natural capital availability,
a determination can be made as to whether that population is behaving in a way that meets
the definition of sustainability.
Perhaps not surprisingly, the average environmental footprint of a citizen of a country like
the United States, Canada, or France is 5, 10, or even 20 times larger than the environmental
footprint of a citizen of a less developed country like Indonesia, Ethiopia, or Bangladesh. Furthermore, the overall environmental footprint of developed countries like the United States
exceeds the amount of land and water resources available to support their populations on a
sustainable basis. In other words, the United States is meeting its current consumption patterns only by drawing down or depleting its own natural capital resources or by “borrowing”
those resources from other countries. You could say that our environmental footprint shows
that we are running a serious ecological deficit. On a global scale, it’s estimated that the entire
human population is consuming resources and generating waste products at a rate that would
require 1.7 planet Earths to be sustainable (Global Footprint Network, 2019). Obviously, we
do not have any other planet Earths available, so we must find ways to reduce the environmental impacts of our activities and consumption if we are to reach a sustainable state.
In terms of our Borneo case study, it’s likely that most residents of that island have relatively
small environmental footprints, based on their direct consumption patterns. However, global
demand from countries like the United States for low-cost palm oil is driving the process
of deforestation for palm oil plantations. This example demonstrates how consumption patterns in one place can have serious environmental impacts in faraway places. As we examine
the impact of food production, water management, fishing, energy use, and waste production
on the environment in the chapters ahead, try to connect these to your own consumption and
resource use patterns. What do you think your own environmental footprint looks like? What
steps could you take to reduce it?
Learn More: Your Environmental Footprint
The Global Footprint Network is the go-to source for information on the idea of
environmental or ecological footprints.
•
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Core Theme: Examining Our Impact
Section 1.5
The Anthropocene and the Sixth Great Extinction
Geologists and earth scientists use a geologic timescale to measure the history of the Earth.
One unit of measure in that timescale is an epoch, a particular period of time defined by distinctive features or events. For roughly the past 10,000 years, a geologic epoch known as the
Holocene, the Earth has been a fairly stable place. There have been no major shifts in climate, no global extinction events, and no periods of widespread volcanic activity or changes
in ocean chemistry.
These relatively stable conditions have provided the perfect setting for human civilizations
to grow and flourish. In that time, the human population of the entire planet has grown from
roughly a few million people, equivalent perhaps to the current population of Los Angeles, to
roughly 7.7 billion people (see Figure 1.7). In just the past 200 years, the human population
has increased by a factor of 8, and the rates of consumption, material and energy use, and
waste generation per person have also increased dramatically.
Figure 1.7: Human population growth
Scientists wonder if Earth can continue to support the current trajectory of human population growth.
7.7 billion
7
7 billion
6.7 billion
6.2 billion
6
5
4 billion
4
3
545 million
2
350 million
1.1 billion
470 million
0
4000
BCE
2000
BCE
1250
CE
1400
CE
1600
CE
1650 1850
CE CE
2001
2007
2011
2019
7 million 27 million
400 million
1975
1
2 billion
1930
Human population (billions)
8
Year
Based on data from “Historical Estimates of World Population,” by U.S. Census Bureau, 2018 (https://www.census.gov/data/tables
/time-series/demo/international-programs/historical-est-worldpop.html); “World Population Prospects 2019,” by United Nations DESA
Population Division, 2019 (https://population.un.org/wpp).
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Core Theme: Examining Our Impact
As a result of these dual trends—growing
numbers of people and increasing rates of
material and energy use—some scientists
now feel that we are entering a new epoch,
one they are calling the Anthropocene.
The Anthropocene, derived from the prefix
anthropo–, or “human,” can be defined as a
geologic age or epoch during which human
activities are the dominant influence on the
environment, oceans, climate, and other
Earth systems. Humans are literally leaving
their mark on the planet, including fundamentally altering the chemical composition
of the atmosphere, oceans, and soils; converting vast areas of open space to cities,
suburbs, farms, and other forms of development; and driving species to extinction
at rates that are 100 to 1,000 times greater
than would otherwise be the case.
Section 1.5
naumoid/iStock/Getty Images Plus
Human activities are changing the planet. Our
choices are affecting the atmosphere, land,
oceans, and other species.
These rapid increases in extinction rates are leading environmental scientists to worry that
we are in the early stages of a sixth great extinction. Scientists believe that since life began
on Earth, there have been five great extinction events—periods in which a significant percentage (70%–95%) of species were wiped out. The first, known as the Ordovician–Silurian
extinction event, occurred roughly 440 million years ago. The most recent, known as the
Cretaceous–Tertiary extinction event, occurred 65 million years ago. It takes millions of years
to bounce back from extinction events and reach comparable levels of species diversity. But
under relatively stable conditions, evolutionary processes create new species faster than others go extinct, and so species diversity will increase over time. Since the last great extinction, the number of species on Earth has grown into the tens of millions. Of these, we know
the most about numbers of mammals and birds but far less about the status of fish, reptiles, amphibians, plants, and invertebrates (organisms without a backbone, such as insects).
Today, as extinction rates increase and far surpass the rate at which evolution develops new
species, we could be losing hundreds if not thousands of species before we have had a chance
to fully understand and study their place in an ecosystem.
Unlike the first five great extinction events, which were caused by natural forces like mass
volcanic eruptions and meteor strikes, the current crisis is a direct result of human actions.
Some of these human actions include pollution, overharvesting and overhunting of species,
the introduction of exotic or invasive species into ecosystems, and the effects of humancaused climate change. (These and other causes of biodiversity loss and extinction will be
reviewed in greater detail in Chapter 2.) However, the most significant cause of species
extinction today is habitat destruction, such as that in Borneo. Widespread conversion of
tropical forests to palm oil plantations, soybean farms, and grazing areas for cattle is wiping out habitat for all kinds of species and contributing significantly to the rapid increase in
extinction rates on the island.
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Core Theme: Taking Action
Section 1.6
In the chapters ahead, consider how human activities like agriculture, fishing, logging, mining, energy use, and waste generation might be altering the planet in profound ways. Also
consider what these activities might mean for other species and for rates of biodiversity loss.
In doing so, consider an idea proposed by the well-known and highly respected evolutionary
biologist E. O. Wilson. Wilson calls for a plan that would set aside one half of the planet as permanently protected areas for other species, an idea known as the Half-Earth Project. Wilson
and others are convinced that such a bold plan is the only way to avert a sixth mass extinction
event. Is such an idea even possible? Can we find ways to meet the needs of a human population soon to exceed 8 billion while leaving room for other species?
Learn More: The Half-Earth Project
The Half-Earth Project is an effort designed to conserve half of the world so as to protect
biodiversity and the ecosystem services it provides. You can learn more about this
project here.
•
https://www.half-earthproject.org
1.6 Core Theme: Taking Action
Faced with evidence that our global ecological footprint is already exceeding capacity and
that we are moving rapidly toward what could be a sixth mass extinction, how do we change
our approach to economic development and meeting our food, water, and energy needs without making things worse? The chapters ahead will present alternative approaches to meeting
our needs side by side with a discussion of current approaches. But how do we know if those
alternatives are worth pursuing, and how much time do we have to decide whether to pursue
them? This section introduces the concepts of uncertainty, scale, risk, and cost–benefit analysis that help environmental scientists and policy makers grapple with these questions.
Uncertainty and Scale
The concepts of uncertainty and scale play an important role in how we define and address different environmental challenges. Uncertainty is a defining characteristic of much of the work
done by environmental scientists. The natural systems that these scientists study are often
so complex that there are always things they can’t be certain about. The scientific method is
one important way in which scientists reduce uncertainty. However, some uncertainty and
even ignorance will still be present, and it’s important to understand this when we examine
evidence of environmental problems and the need to address them. Waiting for “scientific
certainty” before addressing an environmental challenge, a call often made by politicians in
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Core Theme: Taking Action
Section 1.6
cases like climate change, is simply an argument for doing nothing. Instead of waiting
on a certainty that will almost never be
achievable, policies and other approaches
for addressing environmental problems
should be based on the best possible science available at that moment, even if it still
includes elements of uncertainty.
The concept of scale is also important to consider as you undertake the study of environmental science. Environmental issues occur
zanskar/iStock/Getty Images Plus
at many different scales—local, regional,
Action needs to happen early. If we wait for
national, and global—and the larger the
scientific certainty before addressing issues,
scale, the more complex and difficult it
then we might face irreparable damage to our
tends to become to deal with these issues.
environment and its creatures.
For example, small-scale deforestation in
Borneo may be mainly a local scale issue that might be understood and addressed in a fairly
direct fashion. If the scale of that deforestation increases, either because of larger clearings
or a larger number of small clearings that have begun to connect, then we might move to a
regional scale issue with broader impacts. Understanding those impacts and developing ways
to address them also grow in complexity.
At this point, deforestation in Borneo has actually reached the level of a national and global
scale issue. National governments and international environmental groups are involved in
defining and attempting to reduce the problem. Global demand for palm oil and other products is driving deforestation not only in Borneo but also in the Brazilian Amazon and regions
of central Africa. Meanwhile, land use practices in Borneo are resulting in biodiversity loss, air
pollution, and greenhouse gas emissions that are felt on a global scale.
As we study a variety of environmental issues in the chapters ahead, consider how issues
of uncertainty and scale might affect debates about the scope of the problem and possible
solutions. Understand that scientists readily acknowledge elements of uncertainty in their
work and in what they study, but this does not mean they don’t know what they are talking
about, nor is it an excuse for inaction. Also consider how environmental issues operate at
different scales and whether you can see this in your own actions and their impacts on the
environment.
Risk and Cost–Benefit Analysis
We make decisions about risk in our lives every day. Every time you fly on an airplane, drive
a car, walk to work, fall in love, decide to have a family, or enter a business relationship, you
incur a risk that something will go wrong. Therefore, whether you are conscious and deliberate in your choices or reckless and haphazard, you are making a personal form of risk analysis, or risk assessment.
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Core Theme: Taking Action
Section 1.6
In a similar manner, society must make risk analyses in setting environmental policy. You can
see this type of decision making in the news almost every day, along with the political and
economic arguments on a local, state, or national level. For any issue, there are a series of
simple questions that must be addressed before choosing a path of action.
First, one must ask, “What is the probability that a given activity will cause harm?” Because
systems are so complex, it is seldom possible to say action A definitely will cause consequence
B. Scientists build models based on experiments and observation and test their models to the
best of their ability. Rational nonscientists must then develop a course of action based on the
probabilities expressed by the majority of scientists working in the field.
Second, given that outcomes are usually uncertain, one must ask, “What are the consequences
if we do nothing?” In our normal lives, we spread a bigger safety net when the consequences
are serious than we do when they are minor. If the brakes were likely to fail on your car, you
would act more aggressively to get them fixed than you would if the interior dome light were
not working. Because outcomes are never certain, we must balance risk and consequence in
setting environmental policy.
Finally, one must ask, “What are the costs and risks of choosing other options?” In the case
of Borneo, we know with a lot of certainty that current land use practices are not sustainable. We also know that things will only get worse if we do nothing. The real question comes
when we consider what other options might exist. Environmental scientists, economists, and
other development experts can point to many alternative land use practices and economic
models that could help better protect Borneo’s environment while still providing livelihood
opportunities to its residents. However, these alternative approaches may do less to enrich
certain members of society who hold a disproportionate amount of political power. Alternative approaches might make sense from an overall societal perspective, but they might not be
implemented due to local, regional, national, and even global political realities.
One commonly used tool in environmental risk assessment is cost–benefit analysis. It costs
money to install pollution control in factories, mining operations, automobiles, power plants,
and other human-operated systems. These pollution control costs are called internal costs
because they are borne by the industries that produce specific goods and services. Consumers pay internal costs whenever they turn on electricity, pump gasoline into a car, or buy
anything at the store. But if pollution control is nonexistent or inadequate, then everyone has
to pay the cost of a dirty and unhealthy environment. Environmental disasters can result in
sickness, death, destroyed property, loss of work, reduction of home values, and so on. These
societal costs of unregulated pollution are called external costs, or externalities, because they
are outside the activity itself and are not reflected in direct costs. External costs are paid by
everyone in society, regardless of what he or she purchases. Thus, if electric generation creates pollution that causes negative health effects, a poor person who uses little electricity
pays the same price as a rich person who uses a lot of electricity. In fact, a poor person is likely
to pay an even higher price, since many electric power plants and other polluting industrial
facilities (such as oil refineries) tend to be located in low-income areas.
Cost–benefit analyses can be used to compare the cost of pollution control with the cost of
externalities. For example, as the cost of pollution control increases, the cost of externalities decreases. The total cost to society can be found by combining costs of pollution control
and externalities. This total cost typically reaches a minimum when some, but not all, of the
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Bringing It All Together
pollution is controlled. Many suggest that we should strive to achieve this minimum cost even
though this approach accepts some pollution, with its possible discomfort, sickness, and even
death. They argue that the alternative, more expensive pollution control, will slow economic
growth and lead to unemployment, with its own forms of human misery. Others argue that
that cost–benefit analysis is flawed because it ignores both the quality and the value of human
life. How, they ask, can you place a dollar value on the spiritual quality of a walk in the woods
or a swim in a crystal clear mountain stream? How can you measure the economic value of
even one life cut short by cancer? If noneconomic costs of pollution are considered, then more
pollution control becomes desirable.
No one knows the future. But the outcome will affect every person on the planet. We study
environmental science because the issues facing society are complex. There are no absolute
answers. But certainly we—as individuals, municipalities, states, countries, and citizens of the
world—need to develop scientific, economic, and political policy based on an accurate evaluation of the problems we face today and the future we envision for tomorrow. Certainly, an
informed awareness is essential to making the decisions that will affect all of us. As we study
specific environmental issues in the chapters ahead, think about how issues of uncertainty,
scale, and risk might combine to shape perceptions and attitudes about how best to address
that environmental challenge. Also consider whether making use of risk analysis and cost–
benefit analysis might help in guiding policy makers to a better resolution of that challenge.
Bringing It All Together
This opening chapter introduced you to a lot of new terminology, concepts, and ways of
seeing the world. The goal is not to just have you memorize what these terms and concepts
mean but to provide you with the tools you need to further explore a range of environmental
issues presented in the chapters to come. This chapter also provided you with the opportunity to begin to think about your own connection to the environment, in terms of both
your dependence and your impact on it. The next chapter will continue to introduce you to
concepts and terms important to the study of environmental science. The focus of Chapter
2, however, will be on the field of ecology and establishing a natural science foundation. As
we move to Chapter 3 and its focus on human population growth and material consumption,
and then to Chapters 4–9 with their focus on specific environmental issues and challenges,
see if you can connect and apply the terms and concepts introduced in this chapter to your
own understanding of the material.
Additional Resources
Our Connection to the Natural World
We seldom think about the important question of whether we view ourselves as apart from
nature or as a part of nature. In this interesting essay, leadership consultant Kathleen Allen
asks that question and what the answer might mean for each person’s leadership style.
•
https://kathleenallen.net/are-we-a-part-of-nature-or-are-we-apart-from-nature
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Bringing It All Together
This TED Talk argues that nature is not just some pristine wilderness thousands of miles
away from where we live, but rather any open space right outside our door. By going out into
that space, we can develop a relationship with nature that’s good for us and for the planet.
•
Critical Thinking
Educator and speaker Michael Stevens has developed something of a cult following around
his TED Talks on YouTube videos that deal with how we ask and answer questions. His
insights shine a light on how scientists approach their work and use a combination of creative and critical thinking to ask and answer questions about the world around them.
•
https://www.youtube.com/channel/UC6nSFpj9HTCZ5t-N3Rm3-HA
Deforestation in Borneo
There has been a lot of good coverage of the deforestation issue in Borneo in recent years,
including analysis of its causes, history, future trends, and how our own consumption decisions might be implicated in that destruction. This well-written and insightful piece examines the issue and what part you might play in reversing it.
•
https://news.mongabay.com/2018/02/borneo-ravaged-by-deforestation-loses
-nearly-150000-orangutans-in-16-years-study-finds
Sustainability and Sustainable Development
The United Nations is attempting to make the concepts of sustainability and sustainable
development a reality through its Sustainable Development Goals. You can learn more about
these efforts and the idea of sustainability in general at these sites.
•
•
https://sustainabledevelopment.un.org/?menu=1300
https://www.undp.org/content/undp/en/home/sustainable-development.html
The Anthropocene and the Sixth Great Extinction
The idea of the Anthropocene and the question of whether we are now entering this new
epoch are being hotly debated among environmental scientists and geologists. Learn more
about this concept, and the scientific debate surrounding it, here.
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Bringing It All Together
Key Terms
Anthropocene A geologic age or epoch
during which human activities are the dominant influence on the environment, oceans,
climate, and other Earth systems.
biodiversity The variety of life and organisms in a specific ecosystem.
biodiversity hotspot A region that has high
rates of biodiversity and is also experiencing
significant environmental destruction.
cost–benefit analysis A systematic
approach to calculating and comparing the
costs and benefits of different policies.
creative thinking The ability to analyze
and address situations and challenges in
new and creative ways.
critical thinking The objective analysis
and evaluation of an issue in order to form a
judgment.
deforestation The act of clearing of forest
areas.
ecosystem services The beneficial
resources and processes that ecosystems
supply to humans.
ecotourism Tourism that is focused on
natural environments in an effort to help
conserve an area and support the local
economy.
endangered species Species at risk of
extinction.
endemic species Plants and animals that
exist in only one specific geographic region.
environment Everything that surrounds
us, including living and nonliving things; all
physical, chemical, and biological factors and
processes that affect an organism.
environmental footprint A measure of
how much land area and water is necessary to support an individual or a group of
people.
environmentalism A social and political movement committed to protecting the
natural world.
environmental science The study of
how the natural world works, how we are
affected by the natural world, and how we in
turn impact the natural world around us.
extinction The total loss of a species.
habitat The place or set of conditions an
organism depends on for survival.
habitat loss The destruction of specific
habitats.
Holocene The current epoch or geologic
time period, roughly the past 10,000 years.
information literacy The ability to know
when information is needed and the ability
to identify, locate, evaluate, and effectively
use that information to address an issue.
interdisciplinary Pertaining to multiple
disciplines, or areas of study.
natural capital Natural assets such
as trees, soils, streams, oceans, and the
atmosphere.
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Bringing It All Together
risk analysis An evaluation that considers
the probability that a given action will cause
harm, the consequences of inaction, and the
costs and risks of other options. Also known
as risk assessment.
scientific method An approach to research
based on observation, data collection,
hypothesis testing, and experimentation.
species Groups of organisms that share certain characteristics, interbreed, and produce
fertile offspring.
sustainability The maintenance of natural
systems and an ecological balance.
sustainable development The achievement of economic development without the
depletion or destruction of natural systems.
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3
Managing Our Population
and Consumption
sculpies/iStock /Getty Images Plus
Learning Outcomes
After reading this chapter, you should be able to
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Explain how and why the human population has changed over time.
Define determinants of population change.
Interpret an age-structure pyramid.
Deconstruct how the demographic transition model explains population growth over time.
Analyze the effectiveness of direct and indirect efforts to control population growth.
Compare and contrast China’s and Thailand’s population policy.
Describe how population size, affluence, and technology interact to impact the environment.
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Population Change Through Time
Section 3.1
At 2 minutes before midnight on Sunday, October 30, 2011, a 5.5-pound baby girl named Danica May Camacho was born in a government-run hospital in Manila, Philippines. Danica May
was just one of thousands of babies born in the Philippines that day and just one of hundreds
of thousands born around the world each day. Yet Danica May’s birth represented a milestone
for reasons that her parents could never have imagined. The United Nations Population Division decided to symbolically designate Danica May as the world’s 7 billionth person and to
declare October 31, 2011, as the Day of Seven Billion to call attention to the issue of world
population growth. Danica May was greeted with a burst of camera flashes, applause from
hospital staff and United Nations officials, and a chocolate cake with the words “7B Philippines” on it. Her stunned parents also received gifts and a scholarship grant for her future
education.
Was Danica May Camacho actually the world’s 7 billionth person? We will likely never know.
For the United Nations, determining the exact date and precise birth location of the world’s
7 billionth person was beside the point. The fact remains that about 250 babies are born
somewhere in the world every minute. This translates to 360,000 births every day and over
130 million new people on the planet every year. Because humans are dying at less than half
that rate—104 deaths per minute, 150 thousand per day, and 55 million per year—global
population is currently growing at a rate of roughly 75 million per year. In other words, we
are adding the equivalent of a new Germany or Vietnam to the global population each year.
Since Danica May symbolized the 7 billionth person in late 2011, the global population has
continued to grow to over 7.7 billion. Over 700 million more people have joined the human
family in time for Danica May’s seventh birthday.
Whether global population will continue to grow at this rate, slow, or even decline in the
decades ahead has enormous implications for the environment. The number of people on the
planet, combined with the resource and material consumption patterns of those people, are
key drivers of environmental change and an important subject in the study of environmental
science. This chapter will first review how human population has changed over time, increasing gradually over tens of thousands of years before going from 1 billion to over 7 billion in
just the past 200 years. We’ll then examine human population growth using the science of
demography, the study of population changes and trends over time. Demography will help
us better understand how and why population has changed, and it also allows us to examine
what might happen to population in the future. This will be followed by a discussion of population policy and fertility control, utilizing case studies of countries around the world that
have responded in different ways to changing population patterns. Finally, we will consider
how population growth, combined with resource and material consumption patterns, affects
the natural environment. We’ll see that absolute numbers of people in a given population are
just one factor in determining the impact that population will have on the environment.
3.1 Population Change Through Time
Recall from Chapters 1 and 2 that many environmental scientists describe the period we live
in as the Anthropocene, or the age of humans. Human activities are now the dominant influence on the environment, the oceans, the climate, and other Earth systems. We have converted
large areas of the planet’s surface to cities, suburbs, farms, and other forms of development.
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Population Change Through Time
Section 3.1
The waste products of our modern industrial society, including radioactive and other longlived wastes, can be detected in even some of the most remote locations of the globe. Our
activities are fundamentally altering the chemical composition of the world’s atmosphere,
oceans, and soils. And we are now driving other species to extinction at rates that are 100 to
1,000 times greater than “normal” or background rates of extinction.
It may come as some surprise then to consider that for much of human history our very survival as a species was in question. We can divide human history into three broad periods: the
preagricultural, the agricultural, and the industrial.
Preagricultural Period
The preagricultural period of human history dated from over 100,000 years ago to about
10,000 years ago. During this time, humans developed primitive cultures, tools, and skills
and slowly migrated out of Africa to settle Europe, Asia, Australia, and the Americas. Disease,
conflict, food insecurity, and environmental conditions kept human numbers low, perhaps as
low as 50,000 to 100,000 across the entire planet. That’s about the same as today’s population
of a small city in the United States, such as Albany, New York; Trenton, New Jersey; Roanoke,
Virginia; or Tuscaloosa, Alabama. By the end of the preagricultural period about 10,000 years
ago, the human population across the globe had risen to roughly 5 million to 10 million, about
the same as New York City today.
Agricultural Period
The agricultural period of human history, starting about 10,000 years ago, set the stage for
more rapid growth in human numbers. The domestication of plants and animals, selective
breeding of nutrient-rich crops, and the development of technologies like irrigation and the
plow greatly increased the quantity and security of food supplies for the human population.
By the year 5000 BCE (7,000 years ago), there were perhaps 50 million people on the planet.
By 2,000 years ago, that number may have risen to 300 million, about the same as the population of the United States today. Despite the advances brought on by the agricultural revolution, population growth remained low due to warfare, disease, and famine. For example,
between 1350 and 1650, a series of bubonic plagues known as the Black Death ravaged much
of Europe, killing as much as one third of the continent’s population. High birth rates helped
offset high mortality rates, and by the end of the agricultural period 200 years ago, global
population stood at close to 1 billion (Kaneda & Haub, 2018).
Industrial Period
The introduction of automatic machinery around the middle of the 18th century ushered in
the industrial period, the period we are still in today. A combination of factors has caused
dramatic increases in the human population during this time. The Industrial Revolution led to
sharp increases in food production. Advances in science resulted in improved medicines and
medical care. Better understanding of communicable diseases prompted improvements in
sanitation and water quality. All of these developments helped extend life expectancy, reduce
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Population Change Through Time
Section 3.1
mortality rates, and decrease infant mortality. However, because birth rates did not drop at
the same time, human population began to grow more dramatically (see Figure 3.1). While
it took all of human history—over 100,000 years—to reach a global population of 1 billion
around the year 1800, it took only about 120 years to double that number to 2 billion in 1927.
Thirty-three years later, in 1960, world population reached 3 billion. Since 1960 another billion people have been added to the population every 12 to 14 years—1974, 1987, 1999, and
2011 (Population Reference Bureau, 2018).
Figure 3.1: Human population growth
The human population began to increase dramatically starting in the industrial period.
Preagricultural
period
Agricultural
period
Industrial
period
7.7 billion
7 billion
7
6 billion
6
5
4 billion
4
3
0
8000
BCE
5000
BCE
100
CE
1250
CE
1400
CE
1.1 billion
470 million
1600 1650 1850
CE CE
CE
2019
5 million 50 million
2 billion
1999
2011
1
350 million
400 million
545 million
300 million
1974
2
1930
Human population (billions)
8
Year
Based on data from “2018 World Population Data Sheet,” by Population Reference Bureau, 2018 (https://www.prb.org/wp-content
/uploads/2018/08/2018_WPDS.pdf).
Predicting when the 8, 9, or 10 billionth person will be added to the world’s population
depends on assumptions about human fertility and health trends. The decisions that young
people make today about when and if to marry, whether to use contraception and family
planning, and how many children to have will influence future changes to the population. The
United Nations Population Division (2017) now projects that world population will grow to
8.6 billion by 2030, 9.8 billion by 2050, and 11.2 billion by 2100. Whether we hit the 11.2 billion mark in 2100, far surpass it, or never actually reach it at all will depend in large part on
decisions made by what is known as the “largest generation.” As of 2018, well over 40% of
the world’s population was younger than 25 years old, and nearly 2 billion people were under
age 15 (United Nations Population Division, 2017). How the decisions made by these young
people will affect future global population is the focus of Section 3.2.
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Demographics
Section 3.2
3.2 Demographics
The science of demography focuses on the statistical study of human population change. The
word demography is derived from the Greek words demos (“people”) and graphy (“field of
study”). A demographer is a person who studies demography, and demographers focus their
research on demographic trends and statistics. As complex as the study of human populations
may seem, it really boils down to understanding a handful of variables and measures that
together determine changes in human numbers.
Birth and Death
The most basic determinants of a change in any given population are birth rates and death
rates. Demographers measure births and deaths in a very specific way, using what they call
crude birth rates and crude death rates. The crude birth rate (CBR) is the number of live
births per 1,000 people in a given population over the course of 1 year. Likewise, the crude
death rate (CDR) is the number of deaths per 1,000 people in a given population over the
course of 1 year.
The best way to illustrate how CBR and CDR interact to determine population change is
through a simple example. Imagine a small village or town cut off from the outside world. At
the start of the year, there were 1,000 people in this village, but over the next 12 months, 20
children were born and 8 people died. How do these numbers translate into CBR and CDR?
What does this mean for the overall population and rate of population growth? In this case,
the CBR would be 20 and the CDR would be 8. The rate of population growth, what demographers call the rate of natural increase—birth rates minus death rates, excluding immigration and emigration—would be CBR – CDR, or 20 – 8 = 12, or 1.2% of the population of 1,000,
leaving the population of the village at the end of the year to be 1,012.
Migration
In reality, towns and villages are typically not cut off from the outside world, so
demographers also consider immigration
and emigration as factors in population
change. Immigration is people moving
into a given population, while emigration
is people moving out of that population. As
with the rate of natural increase, demographers determine the net migration rate
as the difference between immigration and
emigration per 1,000 people in a given population over the course of 1 year.
Karen Kasmauski /SuperStock
When calculating population change,
immigration and emigration must also
be considered.
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Demographics
Section 3.2
Fertility
Another important statistic that demographers focus on is the total fertility rate (TFR). The
TFR is the average number of children an individual woman will have during her childbearing years (currently considered to range from age 15 to 49). In preindustrial societies, fertility rates were often as high as 6 or 7. This was due to a number of factors. Since most were
engaged in labor-intensive agriculture, large families were considered an asset. Because so
many children died in infancy or childhood, women tended to have more children to ensure
that at least some would survive. Earlier age at marriage, lack of contraception, and cultural
factors also played a role in high fertility rates. Yet human populations grew slowly or not at
all in preindustrial societies because death rates were also high.
It may seem like fertility rates (TFR) and birth rates (CBR) are measuring the same thing,
but that’s not the case. Recall that CBR is the number of births per 1,000 people in a given
population over 1 year. TFR is the average number of children an individual woman will have
during her childbearing years. A given population could be characterized by a high TFR and
a low CBR if there were very few women of childbearing age. Likewise, there could be a low
TFR and a high CBR if a large percentage of the population were women of childbearing age.
Age-Structure Pyramids
The link between fertility rates, the age structure of a population, and overall birth rates
has led demographers to develop a visual tool they call an age-structure pyramid. Agestructure pyramids, also called population pyramids, are a simple way to illustrate graphically how a specific population is broken down by age and gender. Each rectangular box in an
age-structure pyramid diagram represents the number of males or females in a specific age
class—the wider the box is, the more people there are.
Age-structure pyramid diagrams for Uganda, the United States, and Japan are shown in Figure
3.2. Demographic data on CBR, CDR, TFR, immigration, and emigration for these countries are
listed in Table 3.1. Demographers looking at these three age-structure pyramids could tell you
immediately that Uganda is experiencing high rates of population growth, the United States
is growing slowly or is stable, and Japan’s population is in decline. How do they know this?
Table 3.1: Demographic data for Uganda, the United States, and Japan
Country
CBR
(per 1,000)
CDR
(per 1,000)
World
19
7
Uganda
United States
Japan
41
12
8
9
9
11
TFR
Net migration
rate
(per 1,000)
Rate of natural
increase
(percentage)
2.4
N/A
1.2
1.8
3
5.4
1.4
–1
3.2
1
–0.3
0.3
Source: “2018 World Population Data Sheet,” by Population Reference Bureau, 2018 (https://www.prb.org/wp-content/uploads
/2018/08/2018_WPDS.pdf).
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Demographics
Section 3.2
Figure 3.2: Age-structure pyramids for Uganda, the United States,
and Japan
The age-structure pyramids for these three countries can tell us what to expect of each country’s
population growth.
Uganda – 2018
Male
Female
100+
95–99
90–94
85–89
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
05–09
00–04
4.8
4.0
3.2
2.4
1.6
Population (in millions)
0.8
0
0
Age Group
0.8
1.6
2.4
3.2
4.0
Population (in millions)
United States – 2018
Male
4.8
Female
100+
95–99
90–94
85–89
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
05–09
00–04
18
15
12
9
6
3
Population (in millions)
0
0
3
Age Group
6
9
12
15
Japan – 2018
Male
18
Population (in millions)
Female
100+
95–99
90–94
85–89
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
05–09
00–04
6
5
4
3
2
Population (in millions)
1
0
0
Age Group
1
2
3
4
5
6
Population (in millions)
Data from “International Data Base,” by US Census Bureau, 2018 (https://www.census.gov/data-tools/demo/idb/informationGateway.php).
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Demographics
Section 3.2
Uganda
In the case of Uganda, the large numbers of people in the age classes for 0–4, 5–9, and 10–14
years suggest that the fertility rate and birth rate must be high, and the data in Table 3.1
confirms this. When the TFR is much higher than 2, it means that women in that population
are having more children than are needed to “replace” the parents and maintain a certain
population. This is why demographers typically refer to 2 as the replacement rate. Uganda’s
fertility rate of 5.4 means that, on average, each woman of childbearing age in that country is
giving birth to more than 5 children over her lifetime. And because this number is far higher
than the replacement rate of 2, Uganda’s population is growing at an annual rate of 3.2%.
Even if fertility rates in Uganda were to be immediately reduced to around 2, the population
would continue to grow for a few more decades because there are so many female children
below age 15. This large number of young girls who have yet to enter their childbearing years
creates built-in momentum for population growth, which demographers refer to as demographic momentum.
United States
The situation in the United States looks quite different than that of Uganda. Instead of being
wide at the bottom, the age-structure pyramid for the United States is fairly even for ages
between 0 and 70 or 75. This suggests that fertility rates in the United States must be close to
the replacement rate and that birth rates and death rates are roughly similar to each other. The
data in Table 3.1 confirms this. The fertility rate in the United States of 1.8 even suggests that
the United States is below the replacement rate. If fertility rates in the United States remain
at current levels, and if net migration stays the same or declines, the population growth rate
in the United States will approach zero and possibly even turn negative in the years ahead.
Japan
On the complete opposite end of the spectrum from Uganda is Japan. Japan’s age-structure
pyramid actually gets wider at the middle and upper portions, suggesting that fertility rates
are well below replacement levels and that overall population is stable or declining. Table 3.1
confirms this. The TFR in Japan is currently 1.4, and the CBR of 8 is lower than the CDR of 11.
Overall, Japan’s population is currently declining at a rate of –0.3% annually, with moderate
levels of positive net migration helping slow the rate of population decline.
Learn More: Visualizing Population Growth
After reviewing all of the demographic terms and concepts, it might seem challenging to try
to put them together and get a picture of how human populations change over time. This
very simple video developed by National Public Radio at the time when world population
hit 7 billion does a very good job of helping show how populations can change over time in
response to just a handful of changing demographic factors—namely birth rates and death
rates. See if the concepts presented help reinforce the material you just finished reading.
https://www.npr.org/2011/10/31/141816460/visualizing-how-a-population-grows-to-7-billion
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The Demographic Transition
Section 3.3
3.3 The Demographic Transition
For most of human history, both birth rates and death rates were relatively high, resulting in
slow population growth. It was not until the time of the Industrial Revolution that this rough
balance between birth and death rates begin to shift dramatically. Life expectancies increased
and infant mortality and overall death rates declined—but birth rates generally remained
high. In other words, the sudden increase in global population from 1 billion to over 7 billion in just 200 years was not because people started having more children, but because of
a divergence or widening gap between birth rates and death rates as fewer people died. At
first, most of this population increase was concentrated in the more industrialized, developed
countries, where advances in food supply, medicine, and sanitation were more widespread.
By the second half of the 20th century, this population growth began occurring in developing
countries as these advances became available there as well.
Demographers use a model called the demographic transition to explain and understand the
relationship between changing birth rates, death rates, and total population (see Figure 3.3).
Phase 1 of the demographic transition model shows how human populations in preindustrial
societies were generally characterized by high birth and death rates. These tended to cancel
out one another and resulted in a fairly stable population. In Phase 2, as death rates begin
to decline and birth rates remain high, the population increases. In Phase 3, as populations
become more urbanized and as expectations of high infant mortality decline, birth rates also
begin to drop. However, birth rates still exceed death rates, resulting in a continued natural
increase in the population. Not until Phase 4 of the demographic transition do birth rates and
death rates begin to converge again, and overall population begins to show signs of stabilizing.
Figure 3.3: The demographic transition
Births and deaths (per thousand per year)
The four stages of demographic transition show the change in population growth that a country
experiences over time as it develops and industrializes.
50
Total population
Death rate
Birth rate
40
30
20
10
0
Phase 1:
Preindustrial
Phase 2:
Transitional
Phase 3:
Industrial
Phase 4:
Postindustrial
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The Demographic Transition
Section 3.3
Contributing Factors
It’s instructive to review some of the main factors that trigger changes in birth and death rates
and move countries through various stages of the demographic transition.
A population’s death rate will generally begin to drop when three things happen.
1. The food supply increases and becomes more stable.
2. Sanitation practices, such as sewage treatment, improve.
3. Advances in medicine, such as the development and use of antibiotics, occur.
All these factors were prevalent in developed countries during the latter part of the 19th
century and into the 20th century, and death rates declined accordingly. For example, death
rates in the United States were roughly 29.3 for every 1,000 people in 1850, and the average
life expectancy at birth at that time was only about 40. By 1900 death rates had dropped to
17.2, and life expectancy at birth had increased to about 50. After U.S. death rates spiked to
almost 20 during a global influenza outbreak in 1918, they continued to drop to 8.4 by 1950,
roughly where they remain to this day, along with an average life expectancy of 78.7 (Arias,
Xu, & Kochanek, 2019).
While we might expect birth rates to drop at roughly the same rate and at the same time as
death rates, birth rates often remain high due to cultural factors, a desire for large families
in rural households, and expectations of high infant mortality. Over time, however, cultural
attitudes toward family size can change. Likewise, the need for a large family decreases as a
population urbanizes and fewer people are engaged in labor-intensive agriculture. Finally,
infant and child mortality rates fall as sanitation and medical care improve.
Developed Countries Versus Developing Countries
The United States and other developed countries were well into Phase 2 or 3 of the demographic transition by the start of the 20th century. Today these countries are in Phase 4, with
very low fertility rates, low birth rates, and low death rates. In contrast, many developing
countries were still in Phase 1 or 2 of the demographic transition as late as 1950. These countries had not seen the advances in medicine, food supply, clean water, and sanitation that the
developed countries had achieved. In addition, many developing countries were still largely
rural and dependent on agriculture, a situation that tends to promote high f…
