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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
The easy way to score high in Environmental Science Environmental science is a fascinating subject, but some students have a hard time grasping the interrelationships of the natural world and the role that humans play within the environment. Presented in a straightforward format, Environmental Science For Dummies gives you plain-English, easy-to-understand explanations of the concepts and material you'll encounter in your introductory-level course. Here, you get discussions of the earth's natural resources and the problems that arise when resources like air, water, and soil are contaminated by manmade pollutants. Sustainability is also examined, including the latest advancements in recycling and energy production technology. Environmental Science For Dummies is the most accessible book on the market for anyone who needs to get a handle on the topic, whether you're looking to supplement classroom learning or simply interested in learning more about our environment and the problems we face. * Presents straightforward information on complex concepts * Tracks to a typical introductory level Environmental Science course * Serves as an excellent supplement to classroom learning If you're enrolled in an introductory Environmental Science course or studying for the AP Environmental Science exam, this hands-on, friendly guide has you covered.
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Veröffentlichungsjahr: 2012
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Environmental Science For Dummies®
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Table of Contents
Environmental Science For Dummies®
by Alecia M. Spooner
Environmental Science For Dummies®
Published by John Wiley & Sons, Inc.111 River St. Hoboken, NJ 07030-5774 www.wiley.com
Copyright © 2012 by John Wiley & Sons, Inc., Hoboken, New Jersey
Published simultaneously in Canada
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Library of Congress Control Number: 2012941753
ISBN 978-1-118-16714-4 (pbk); ISBN 978-1-118-22630-8 (ebk); ISBN 978-1-118-23961-2 (ebk); ISBN 978-1-118-26421-8 (ebk)
Manufactured in the United States of America
10 9 8 7 6 5 4 3 2 1
About the Author
Alecia M. Spooner teaches Earth and environmental sciences at Everett Community College in Everett, Washington. She has degrees in anthropology (a BA from the University of Mississippi), archaeology (an MA from Washington State University), and geology (an MS from the University of Washington). In graduate school, she reconstructed paleoclimate and paleoenvironments from fossil pollen records in lake sediments of the Pacific Northwest. She teaches by using active learning and inquiry. She lives in Shoreline, Washington, with her husband, two boys, a cat, and two chickens.
Dedication
To the many teachers who inspired me to look at the world more closely.
“We shall never achieve harmony with land, any more than we shall achieve absolute justice or liberty for people. In these higher aspirations, the important thing is not to achieve but to strive.”
—Aldo Leopold
Author’s Acknowledgments
This book was created with support and encouragement from the following people: Igor, Pasha and Dima, Mom and Dad, Heather and Julie, Alli and Holly, Janice and Kysa, Rene and Matt, and Elizabeth, Amanda, and Lindsay. Thank you.
Publisher’s Acknowledgments
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Introduction
Environmental science is the study of Earth’s environment. To study the environment, scientists draw from many other disciplines, including chemistry, geography, economics, and everything in between. No wonder students new to environmental science often find themselves dizzy at the breadth of information needed to study and solve environmental problems.
Fortunately, you’ve found Environmental Science For Dummies! Regardless of whether you picked up this book to help you through a science class or to begin an independent exploration of environmental science, I hope it’s a useful reference for you, providing an introduction to the most important concepts and issues in modern environmental science.
I’ve written this book to cover as many environmental science concepts as possible, while at the same time helping you understand how these concepts apply to your life. If you’re already familiar with some of the topics explained in the book, perhaps this book will help renew your interest in environmental studies and sustainable living. If these topics are completely new to you, I hope it helps you realize that you can take action daily and make choices that affect your environment in a positive way.
About This Book
Environmental Science For Dummies presents an introduction to the core concepts in environmental science and the most important issues studied by environmental scientists today.
The topics in environmental science are so intricately linked that there’s simply no way to explain one without explaining a little bit of another as well. In each chapter, I use cross-references to other chapters to help you link together the related concepts and to provide a more complete understanding of the complex topics in environmental science.
Throughout the book, you also find multiple illustrations. These drawings expand on what I’ve written in places where a visual representation may be helpful. But don’t forget to look up from reading once in a while! You have plenty of first-hand experience with the environment. As you read about certain topics or issues, you may find it useful to look at them in the context of your own life.
Conventions Used in This Book
Here are some of the conventions I use in the book to keep things easy to find and follow:
Anytime I use a word that I think you may not have seen before, I put it in italics and define it.
Boldface words highlight a bulleted list or sequence of steps.
Internet and web addresses appear in monotype to help them stand out.
What You’re Not to Read
Throughout this book, you find sidebars highlighted in gray. The sidebars include extra information or particularly interesting tidbits that I thought you might enjoy. I find them interesting — and I hope you do, too — but they aren’t required reading to understand the concepts in the book. Feel free to skip these sidebars, as they’re not integral to the information presented in each chapter.
Similarly, any portion of text with the Technical Stuff icon beside it indicates that it explains or describes a concept in extra detail, beyond what you need to have a basic grasp of the idea. Feel free to skip these portions or to breeze through them.
Foolish Assumptions
As the author of this book, I’ve made some assumptions about you, my reader. For instance, I assume that you live on Earth, drink water, breathe air, and use energy for various things such as heating and transportation. I assume that you’re familiar with basic geography, such as the location of continents and some countries around the world.
However, I don’t assume that you have any background in chemistry, biology, geology, ecology, economics, or any of the other disciplines that are part of environmental science. And you don’t need a background in any of these to benefit from the explanations in this book. Wherever the details of another science are important, I provide those details in my explanations.
Each topic in environmental science could fill an entire book of its own, so if you find that something in particular catches your interest, I encourage you to look for books that offer more detail into that topic specifically.
How This Book Is Organized
I’ve broken this book into chapters and organized those chapters into parts that group topics together. Here’s a brief overview of each part.
Part I: Demystifying Science and the Environment
In Part I, I introduce you to environmental science, the study of Earth’s environment and the living and nonliving things within it. I describe the scientific method and explain how scientists design effective experiments and portray information by using graphs.
This part includes a discussion of matter, the “stuff” that makes up all things, and a quick look at how atoms bond to form molecules. It describes inorganic matter and the important organic molecules that are the building blocks for life. And it includes a chapter on what scientists understand about energy: what it is, how it works, and how it flows. This is where you find details on photosynthesis and cellular respiration.
Part II: Planting the Seed: Foundational Concepts in Environmental Science
Like any science, environmental science has a few key concepts or principles that provide the foundation for greater understanding. In Part II, I introduce you to these concepts, including how to measure human impact with the ecological footprint and how to use the ecosystem as a unit of study.
The plants and animals that inhabit an ecosystem are determined largely by the climate (temperature and moisture) conditions of the region. Scientists link living communities to climate by classifying ecosystems into defined categories called biomes, which I describe in this part.
This part also scratches the surface of population biology, which is the study of how organisms interact with one another. I explain competition, cooperation, and predation within an ecosystem, as well as some of the complex ways that scientists measure and track changes in populations (including human populations) over time.
Part III: Getting Your Needs Met: Earth’s Natural Resources
A major focus of environmental science is how to use and care for Earth’s natural resources so that they can continue to meet the needs of human beings for as long as possible. Part III describes Earth’s natural resources and the issues humans face in trying to conserve them, or make them last.
You’re familiar with some of these resources — water, land, and energy. But you may not realize that the diversity of biological organisms, or biodiversity, is also a natural resource. I describe all these resources in this part and explain why biodiversity is so important and why it’s in danger in many parts of the world. I also explain the pros and cons of alternative energy sources.
Part IV: Giving a Hoot: Pollution and Environmental Quality
Along with managing natural resources, environmental scientists are often asked to help solve problems created by pollution. Part IV covers topics of environmental quality, including air and water pollution. It’s also the place to look for information about what dangerous substances or toxins are present in the environment and how garbage and hazardous waste can be managed to reduce further environmental damage.
This part also addresses what scientists currently understand about Earth’s climate and how human actions continue to affect the global climate system.
Part V: Follow the Recycled Brick Road: A Sustainable Future
The goal of most environmental scientists is sustainability. This means using the environment and its resources in such a way that it can continue to provide for human needs long into the future, possibly forever. In this part, I describe some basic economic principles and explain how shifting your perspective from human-centered to ecosystem-centered may lead you to make more sustainable choices as a consumer.
Millions of people with different desires and priorities share Earth. In this part, you uncover some of the most successful policies across the U.S. and across the world that have come about to help protect the environment and conserve Earth’s resources for future generations.
Part VI: The Part of Tens
In the final part of Environmental Science For Dummies, you find three lists. The first is a list of ten simple ways to live life more sustainably. The second describes ten examples of how unsustainable practices have ruined shared resources, or commons. And the last chapter of the book lists ten careers that center on environmental science. You may be surprised at the variety of options you have for working in an environmental science field!
Icons Used in This Book
Throughout this book I use icons to catch your eye and highlight certain kinds of information. Here’s what these little pictures mean:
Anytime you see the Remember icon take notice! I use this icon to highlight important information, often fundamental to the concepts being explained around it or in the same chapter. Other times I use it to highlight a statement meant to help you pull multiple concepts together.
The Tip icon marks information that may be particularly useful to help you study or prepare for an exam. It often marks a helpful way to remember a certain concept.
The Case Study icon brings your attention to real-world examples of particular environmental issues. Case studies are a great way to provide context for the concepts I present in the book.
Anywhere I describe a potential solution for an environmental problem I mark it with a Solution icon.
A few places in this book I offer a little extra detail about a particular topic or concept and mark it with the Technical Stuff icon.
Where to Go from Here
I’ve written this book to function as a reference that you can open to any page and dive into. If you choose to start from the beginning, you’ll find the information organized in what I hope is a logical way that answers your questions as soon as you think to ask them! But you can also browse the table of contents to find topics you’re interested in knowing more about and then turn to the chapters on those topics.
If you’ve never thought much about how you’re connected to everything around you, you may want to start with Chapter 6, which explains what an ecosystem is and does. This chapter may dramatically change your perspective!
If you’re intrigued by the idea of alternative energy sources, flip to Chapter 14, where I cover many different ways to fuel daily living without using fossil fuels (coal, gas, and oil) or nuclear power. Environmental scientists have found ways to capture or produce energy in cleaner, more efficient ways than have ever been possible before.
For a real wake-up call, turn to Chapter 18 to see how the packaging and convenience of modern life (think bottles of water, to-go containers, and plastic utensils) have resulted in oceans full of trash. In particular, plastic bits that don’t decompose are interfering with ocean ecosystems, which is just one of the consequences of waste I describe in that chapter.
Part I
Demystifying Science and the Environment
In this part . . .
At its core, environmental science is like any science — based on a methodical way of asking and answering questions to expand the human understanding of the natural world.
In this part, I describe how the scientific method shapes the process of learning about the environment. I also cover foundational scientific ideas about what makes up everything around you (atoms, molecules, and compounds) and how energy moves things through the environment. This is also where you find out how green plants capture energy from the sun and transform it into sugar through the process of photosynthesis.
Chapter 1
Investigating the Environment
In This Chapter
Applying a scientific approach
Studying environmental systems
Protecting natural resources
Reducing pollutants in the air and water
Looking forward to a sustainable future
In its simplest terms, environmental science is the study of the air you breathe, the water you drink, and the food you eat. But environmental scientists study so much of the natural world and the way humans interact with it that their studies spill over into many other fields. Whether you’re a student in a college course or someone who picked up this book to find out what environmental science is all about, you’ll find that the ideas in this book apply to your life.
Like any living creature, you depend on environmental resources. More importantly perhaps is the fact that humans, unlike other living creatures, have the ability to damage these resources with pollution and overuse. This chapter provides a quick overview of the environment, its systems, and its many resources. It also talks about what humans can do to reduce their impact on the environment today and into the future. After all, maintaining the health of the Earth and its resources at both the local and global level is something everyone has a stake in.
Putting the “Science” in Environmental Science
Environmental science draws on knowledge from many different fields of study, including the so-called hard sciences like chemistry, biology, and geology and the social sciences like economics, geography, and political science. This section offers a quick overview of some of the scientific concepts, such as how to apply the scientific method to answer questions, that you need to be familiar with as you start your exploration of environmental science. I explain these foundational scientific concepts in more detail throughout the rest of Part I.
Using the scientific method
The scientific method is simply a methodical approach to asking questions and collecting information to answer those questions. Although many classes teach it as something that only scientists use, you use it just about every day, too.
You may not write down each step of the scientific method when you use it, but anytime you ask a question and use your senses to answer it, you’re using the scientific method. For example, when standing at a crosswalk, you look both ways to determine whether a car is coming and whether an approaching car is going slow enough for you to safely cross the street before it arrives. In this example, you have made an observation, collected information, and based a decision on that information — just like a scientist!
The power of the scientific method is in the way scientists use it to organize questions and answers. It helps them keep track of what’s known and what’s unknown as they gather more knowledge. This organization becomes particularly important when they study large, complex systems like those found in the natural world. Scientists always have more to learn about the natural world, and using the scientific method is one way that they can follow the path of scientific investigation from one truth to another. Turn to Chapter 2 for more on the scientific method.
Understanding the connection between atoms, energy, and life
Studying the environment includes studying how matter, energy, and living things interact. This is where other fields of study, such as chemistry, physics, and biology, come into play. Here are just a few of the core ideas from these sciences that you need to understand as you study environmental science:
All matter is made of atoms.
Matter is never created or destroyed, but it does change form.
Living matter, or life, is made up of complex combinations of carbon, hydrogen, and oxygen atoms.
Most of the energy at Earth’s surface comes from the sun.
Energy transfers from one form to another.
Living things, or organisms, either capture the sun’s energy (through photosynthesis) or get their energy by eating other living things.
Analyzing the Earth’s Physical Systems and Ecosystems
The environment consists of many different systems that interact with one another on various levels. Some systems are physical, such as the hydrologic system that transfers water between the atmosphere and the Earth’s surface. Other systems are built on interactions between living things, such as predator-prey relationships.
Scientists recognize that systems can be either open or closed. An open system allows matter and energy to enter and exit. A closed system keeps matter and energy inside of it. Figure 1-1 illustrates both types of systems.
Figure 1-1: Open and closed systems.
Illustration by Wiley, Composition Services Graphics
Very few systems in the natural world are truly closed systems. Scientists view the planet as a closed system in terms of matter (no matter enters or leaves the Earth), but they consider it an open system in terms of energy (energy enters the Earth from the sun). The following sections introduce you to a few of the Earth’s other systems that you need to be familiar with. (Part II goes into a lot more detail on the different systems on Earth.)
Sorting the world into climate categories
One of the most important and complex systems that scientists study is the climate. The climate system includes but is actually much larger than local weather systems. Climate scientists observe how different parts of the Earth are warmed by the sun to greater or lesser degrees, and they track how heat from the sun moves around the globe in atmospheric and ocean currents.
The movement of heat and water around the Earth sets the scene for living things. Every living plant and animal has a preferred range of temperature and moisture conditions. The patterns of living communities on Earth are called biomes. Scientists define each biome according to its temperature and moisture levels and the types of plants and animals that have adapted to live within those limits. Understanding the complex link between climate factors and the distribution of life on Earth has become even more important as scientists document changes in the global climate and predict more dramatic changes to come. Turn to Chapter 7 for details on global climate patterns and biomes.
Dividing the Earth into ecosystems
Within every biome, scientists recognize various ecosystems, or communities of living organisms and the nonliving environment they inhabit. Studying how matter and energy move around ecosystems is at the core of environmental science. Specifically, scientists recognize that
Matter is recycled within the ecosystem.
Energy flows through an ecosystem.
Whether they’re small or large, discrete or overlapping, ecosystems provide a handy unit of study for environmental scientists. Because plants are the energy base of most ecosystems (capturing energy from the sun), the type and number of plant species in an ecosystem determine the type and number of animals that the ecosystem can support. See Chapter 6 for details on ecosystems.
Observing the interactions between organisms within an ecosystem
Scientists called ecologists are particularly interested in how living things interact within an ecosystem. Plants and animals compete with one another for access to water, nutrients, and space to live. Evolution by natural selection has resulted in a wide array of survival strategies. Here are some examples (see Chapter 8 for more details):
Resource partitioning: When two species, or types of animals, depend on the same resource, they may evolve behaviors that help them share the resource. This is called resource partitioning. An example is when one species hunts at night, while another hunts the same prey during the day.
Coevolution:Coevolution occurs when a species evolves in response to its interaction with other species. Scientists have documented multiple cases of insects and the plants they feed on (and help pollinate) evolving to become more and more suited to one another over time.
Symbiosis: Organisms that benefit from an interaction with another species live in what scientists call symbiosis. Symbiotic relationships between organisms may benefit both individuals, benefit only one while harming the other (such as with a parasite), or benefit one without harming the other.
Supplies Limited! Natural Resources and Resource Management
Environmental scientists do a lot of research to find ways to meet the needs of human beings for food, water, and energy. The environment provides these natural resources, but if their users (namely humans) don’t care for them properly, they can be reduced, damaged, or destroyed. Managing natural resources for the use of human beings now while ensuring that the same resources will be available for humans in the future is called conservation.
Factoring in food, shelter, and more
People need food, water, air, and shelter to survive. But as human populations have grown into the billions, they’ve tested the ability of the environment to provide enough food, fresh water, and shelter. In Part III, I describe methods of sustainable agriculture and water conservation that can help meet the needs of so many people. (So far, there’s still plenty of air to go around.)
Other resources that people depend on are less obvious, such as the biological diversity, or biodiversity, found in certain regions. Human actions have reduced biodiversity around the world, particularly in biodiversity hotspots, or regions with a combination of high levels of diversity and increasing human impacts. In Chapter 12, I explain what biodiversity is and why it’s so important.
Thinking about energy alternatives
One of the most critical natural resources that modern living depends on is energy. Energy in most ecosystems streams from the sun every day, but to fuel modern life, humans have tapped into the stored energy of fossil fuels hidden deep in the Earth. Unfortunately, fossil fuel sources of energy are both limited in supply and damaging to the Earth’s environment when humans burn them as fuel.
Searching for alternative sources of energy is an important part of environmental science research. Some of the current alternatives to fossil fuels include
Solar energy
Wind energy
Hydro (river) energy
Tidal and wave energy
Geothermal heat
Fuel cell electricity
Liquid biofuel energy
I describe the pros and cons of these various options and explain how each one can help meet the energy needs of modern life in Chapter 14.
Keeping Things Habitable
Clean air, fresh water, food, and a safe place to live are critical to the survival of human beings. Unfortunately, in most parts of the world, decades of pollution have damaged environmental quality and endangered human health. How humans can repair the damage already done to air, water, and land resources is the focus of Part IV.
Clearing the air (and water)
You may be familiar with some of the problems caused by air pollution: smog, acid rain, ozone depletion, and lung disease. In Chapter 15, I describe all the ways air is polluted and the results of pollution on ecosystems and human health. Similarly, in Chapter 16, I describe the sources and effects of water pollution.
In both cases, scientists classify the source of pollution as one of the following:
Point source pollution: Point source pollution flows directly out of a pipe or smokestack and is easy to locate and regulate.
Nonpoint source pollution: Nonpoint source pollution enters the air or water from a diluted or widespread area, such as when rainfall washes everything from city streets into nearby waterways via storm drains. This type of pollution is difficult to pinpoint and nearly impossible to regulate.
Tracking toxins and garbage
Toxic substances are all around you — in your home and in the environment. Many identified toxins today were once acceptable chemicals to use in agriculture or manufacturing. In some cases, scientists know the effects of a toxin, and as a result, it’s no longer allowed to be used. In other cases, however, research is still being done to determine the danger of chemicals found in many household products.
In some places, toxins have entered the environment from improper waste disposal. Humans have to store (or burn) trash and other manmade garbage somewhere. All too often that garbage ends up in the oceans. I describe the problems related to waste disposal in Chapter 18.
When toxins enter an ecosystem, whether directly or as a byproduct of trash and hazardous waste, they can disrupt the ecosystem and cause harm to living things. Toxins often bioaccumulate, or build up in the cells of an organism. In some cases, the toxic substance is present in the environment at harmless levels but becomes more and more concentrated as it moves through the food chain. By the time top predators feed on lower predators, they’ve been poisoned by the biomagnification of the toxin. See Chapter 17 for more details on toxins and the effects they can have on the health of living things.
Influencing climate
These days, few environmental issues appear in the media and politics as often as modern climate change, or global warming. In Chapter 19, I explain how the greenhouse effect on Earth is beneficial and how greenhouse gases, both natural and manmade, change the composition of the atmosphere and affect climate patterns around the globe.
Some of the changes scientists expect with future climate warming include droughts in regions that are already water stressed, rising sea levels, and marine ecosystem disruption. The climate is definitely warming, so I also describe ways that humans can mitigate, or repair, the damage already done and adapt to a future climate that’s very different from anything modern human civilization has experienced before.
Imagining the Future
Managing the Earth’s resources so that human needs and desires today don’t reduce the planet’s ability to support future generations is called sustainability. The future is in your hands. The choices you make each day and the leaders you choose to create policies determine how people share, use, or abuse the Earth’s resources in the coming decades. Regardless of your religious, political, cultural, or national values, you have a stake in your right and the rights of your children to a healthy, clean environment.
Realizing a sustainable economy
Many people think the biggest challenge in making sustainable choices is the cost, and some politicians want you to believe that a sustainable economy will destroy the world. Neither of these views is true. In Chapter 20, I describe some basic economic ideas and offer ways to look at the economy more sustainably. The transition to a more sustainable economy will take time, but in the long run, it’ll be worth the effort!
Putting it on the books: Environmental policy
In Chapter 21, I introduce you to some of the most important and effective international agreements on global stewardship. The Montreal Protocol is one international agreement that was created to protect the environment. Specifically, this agreement reduced the production of ozone-damaging molecules around the world and halted the destruction of the ozone layer.
You may not have realized this, but 50 years ago many of the rivers, lakes, wetlands, and shorelines in the U.S. were much more polluted than they are today. After Congress amended the Clean Water Act in the 1970s, major cleanups began, improving water quality across the nation during the next few decades. These days new issues, such as climate change and environmental toxins, have taken a front seat in environmental science and policy. But no matter what issues are currently taking up the most attention on TV and in scientists’ labs, the choices you and I make every day will determine the future health of the global environment.
Chapter 2
Lab Coats and Microscopes: Thinking Scientifically
In This Chapter
Getting to know the scientific method
Illustrating data with graphs
Measuring the unknown
Thinking critically about science in the media
If you think of science as lab coats, microscopes, test tubes, pages and pages of data, and wild-haired scientists, you may be a little intimidated by the science part of environmental science. But in actuality, you perform acts of science every day; you just may not know it.
In this chapter, I describe what scientific thinking is, and I explain how scientists look at the world by asking and answering questions in an organized way (ahem, anyone heard of the scientific method?). I also introduce the most common ways that scientists and environmental scientists, in particular, present what they’ve learned by using graphs and statistics. Finally, I explain what good scientific news reporting looks like so you can evaluate the science you read about or see in the news.
Asking and Answering Questions with the Scientific Method
Scientists ask questions about the world around them just as you do. Is it cold outside today? Will a quarter of a tank of gas get me to work and back? Why do roses smell so good? Thinking scientifically simply means that when you ask a question, you go about answering that question in a methodical way, using logical reasoning. This way of asking and answering questions is often called the scientific method.
In this section, I describe the two approaches to logical reasoning, and I walk you through the various steps in the scientific method, including the ins and outs of designing experiments and the added step that professional scientists take — having their peers review their work.
Reasoning one way or another: Inductive versus deductive
Scientists construct their understanding of nature through logical reasoning, in which they follow a sequence of statements that are true to their conclusion. The two types of logical reasoning are
Inductive reasoning:Inductive reasoning begins with a detailed truth about something and uses that truth to construct a generalized understanding of how the greater system or phenomenon functions. Using inductive reasoning to understand complex systems can be tricky because a few small details may not accurately represent the entirety of the system. Inductive reasoning is the opposite of deductive reasoning.
Deductive reasoning:Deductive reasoning starts with broad generalizations and gradually focuses in on a specific statement of assumed truth. Deductive reasoning is most useful when you don’t understand all the details of something but you can observe some of its outcomes. On the path of deductive reasoning, a scientist rules out one option after another until she has narrowed the field of truth down to just one or a few reasonable explanations. When a scientist proceeds with testing her hypothesis (see the next section), she’s using deductive reasoning.
Working through the scientific method
Most students have encountered the scientific method at some point in their grade school education. For example, many teachers ask their students to write down each step they take while performing a lab experiment. In case you’ve forgotten a few things since grade school, I walk you through the main steps in the scientific method here:
1. Make an observation.
An observation is just information you collect empirically (meaning that you collect the information by using your senses — sight, hearing, touch, taste, and smell) and objectively (meaning that anyone else in the same place, using the same methods, would observe the same information that you do).
Empirical and objective observations are what scientists call data. Scientists use data to create new hypotheses that they can then test by collecting more information, or experimenting.
2. Create a hypothesis.
Based on your observation and any prior knowledge you may have from previous observations or experiences, you create a hypothesis, which is simply an inferred or assumed understanding based on your observations.
3. Design and conduct an experiment.
After you have your hypothesis, you need to find a way to determine whether it’s correct. Testing your hypothesis requires that you conduct an experiment (see the next section for details on this step).
4. Analyze the results and draw a conclusion.
After you perform an experiment, you have more observations or data to incorporate into your overall understanding of your hypothesis. At this point, you may want to create a new hypothesis (if the data you collected during your experiment proved your original one to be wrong) and perform further experiments, or you may have enough new information to draw a conclusion, expanding your understanding of what you initially observed.
Although scientists use this method in their laboratories and in field settings where they collect scientific data on a daily basis, you use the scientific method every day without even realizing you’re doing so. Take for example your morning shower: You turn on the water by adjusting the dial to what you think will be the right temperature and then you wait a few minutes:
Observation: After a few minutes have passed, you observe steam forming around the flowing water.
Hypothesis: You propose a hypothesis: The water is just the right temperature now.
Experiment: Then you test the hypothesis with an experiment. You stick your hand in the water and observe the temperature.
Results and conclusion: After you’ve collected data about the temperature of the water, you determine whether your hypothesis is true: Either the temperature is just right, or it isn’t just right. If it’s too hot, you infer that adding more cold water will make it the right temperature (and vice versa). Eventually, after you’ve collected enough data and made a number of inferences and adjustments, you’ll find the water temperature that’s just right for you to hop in the shower.
The point of this example is to illustrate that the scientific method isn’t something magical or some kind of secret code. It’s simply a way of describing how human beings ask questions and collect information to answer those questions. Environmental scientists use this methodical approach over and over again to understand the natural world.
Designing experiments
Experimental design is an extremely important part of the scientific method. When a scientist seeks to prove or disprove her hypothesis, she must carefully design her experiment so that it tests only one thing, or variable. If the scientist doesn’t design the experiment carefully around that one variable, the results may be confusing.
The two main types of experiments scientists use to test their hypotheses are
Natural experiments:Natural experiments are basically just observations of things that have already happened or that already exist. In these experiments, the scientist records what she observes without changing the various factors. This type of experiment is very common in environmental science when scientists collect information about an ecosystem or the environment.
Manipulative experiments: Other experiments are manipulativeexperiments, in which a scientist controls some conditions and changes other conditions to test her hypothesis. Sometimes manipulative experiments can occur in nature, but they’re easier to regulate when they occur in a laboratory setting.
Most manipulative experiments have both a control group and a manipulated group. For example, if a scientist were testing for the danger of a certain chemical in mice, she would set up a control group of mice that weren’t exposed to the chemical and a manipulated group of mice that were exposed to the chemical. By setting up both groups, the scientist can observe any changes that occur only in the manipulated group and be confident that those changes were the result of the chemical exposure.
When designing manipulative experiments, scientists have to be careful to avoid bias. Bias occurs when a scientist has some preconceived ideas or preferences concerning what she’s testing. These ideas may influence how she sets up the experiment, how she collects the data, and how she interprets the data. To avoid this bias, a scientist can set up a blind experiment, in which other scientists set up a control group and a manipulated group and don’t inform the scientist who’s actually observing the experiment which one is which.
Using scientific models to test hypotheses
You may have heard your local weather reporter talk about weather models and model predictions for the weekend ahead. Or maybe you’ve heard about climate models and their predictions of future climate change (see Chapter 19 for details). In both cases, the models may seem like crystal balls that can predict the future. However, climate and weather models are powerful tools that scientists use to understand complex global systems and predict how those systems will act in the future.
In some ways, a scientific model is very much like a model train or airplane in that it has parts that represent all the details of real life and some models are more detailed than others. Regardless of how detailed scientific models are, scientists can use them to test their hypotheses when studying the real thing is too difficult or, in some cases, impossible.
Take for example a globe: The continents, national borders, and locations of water, mountains, and other features represent what scientists know about the Earth but couldn’t observe directly before satellite pictures were possible. A model of the Earth can be just one piece in a more complex model of the solar system, such as the one illustrated in Figure 2-1.
Figure 2-1: A model of the solar system.
Illustration by Wiley, Composition Services Graphics
These days many scientific models are computer models (rather than physical models like globes) because computers can combine and analyze huge amounts of data much faster than a human brain. In environmental science, you’re likely to encounter numerous detailed and complex models, such as climate models and ecosystem models. Scientists use these complex models to teach others (including you and me) about how large, intricate systems in the natural world function.
Before any scientific model (especially a complex computer model) can be informative, scientists have to do a lot of research to make sure it accurately models interactions in the real world. As part of their research, scientists set up the model and input data about the real world that led to a known event, such as a hurricane. If the computer model, using the real-world data, creates wind patterns, temperatures, wind speeds, and rainfall that are similar to or the same as the conditions in the real hurricane that occurred, then the scientists can be confident that the model will accurately simulate real life.
Asking peers for constructive criticism
One major difference between your everyday use of the scientific method and the way professional scientists use it is that you don’t have to ask all your friends whether they agree that your shower water temperature is just right. Professional scientists, on the other hand, do have to ask for their peers’ opinions about their experiments and the conclusions they draw from them. They do this through a process called peer review.
Any time a scientist completes a research project, she writes a paper or article about it, in which she describes her hypothesis, experiment, results, and conclusions. She sends this article to a peer-reviewed journal, where other scientists who are specialists in the same type of science review her work and determine whether the methods in the experiment make sense and whether the data she collected support the conclusions she made.
If the scientist’s peers think she has done good work, then her article gets published in the journal so that the broader scientific community can learn from what she did. If her peers think her methods need improvement or her conclusions don’t make sense, then they tell her that she needs to improve, clarify, or otherwise revise her study to be more accurate.
After a scientific study has passed the initial peer-review stage and has been published, it’s open for debate among the broader community of scientists and can be very helpful to other scientists who are asking similar questions. In this way, scientists across the globe build a large database of information gathered from all of their experiments.
The careful approach to experimenting and collecting data that scientists have to take to be deemed credible, as well as the rigorous process of peer review they undergo after every major research project, results in scientific progress that appears to move at a snail’s pace. This seemingly slow progress can be extremely frustrating for the general public and policymakers, who want to make decisions now and don’t want to wait until scientists have studied everything scientifically from every angle. (In Chapter 20, I explain the different approaches some policymakers take in light of this.)
Speaking scientifically
Some words that you use in everyday conversation have a very different meaning when you use them to describe science. Here are a few words you may think you know the meaning of, along with what they mean when a scientist uses them:
Hypothesis: A hypothesis is based on observations and states an assumed fact in a way that it can be tested. When scientists are working to rule out incorrect ideas, they may propose a null hypothesis. A null hypothesis usually says something like this: There is no relationship between how much I turn the hot water knob and the temperature of my shower. Testing this hypothesis will prove the null hypothesis false because there is, indeed, a relationship between how much you turn the hot water knob and the temperature of your shower. In some cases, ruling out wrong ideas is an important part of the deductive reasoning process.
Theory: Scientifically speaking, nothing is ever “just a theory.” A theory in science is an explanation of a natural phenomenon that has been tested repeatedly and is currently accepted as a fact. Theories explain why things occur the way they do or offer a mechanism behind what scientists observe. Theories (like any scientific findings) are open to further testing, but a good theory continues to hold true through these tests.
The scientific community isn’t quick to call something a theory, so when it uses the term, such as for the theory of evolution by natural selection in biology, the theory of gravity in physics, or the theory of plate tectonics in Earth science, whatever phenomenon the theory is describing is considered an accepted scientific fact to be improved upon with further testing and observation.
Law: A scientific law explains a process that has been observed, but it doesn’t explain why the process occurs. For example, the law of gravity explains how two objects are attracted to one another, such as how the moon is attracted to the Earth, but it doesn’t explain why the two objects are attracted to one another. To answer that question, you need to refer to the theory of gravity. Note: People often make the mistake of thinking that a scientific theory will someday become a law, thus making it more true or more factual. But that’s not the case. Theories never become laws; they’re two completely different things.
Presenting Data Graphically
One of the challenges that all scientists (especially environmental scientists) encounter is how to share the knowledge they gain from their research and experiments with other people in a way that’s easy to understand. Reading page after page of detailed scientific findings can be difficult or boring even for a scientist. So scientists often turn to more visual ways — namely, graphs — to illustrate their discoveries, share their data, and explain what they’ve found out from their experiments. Scientists can choose from a number of different ways to present data as graphs depending on the type and amount of information they have. Here are three of the most common ones:
Pie charts:Pie charts are circles with pieces that represent different categories of some type of information. Each slice of pie may be smaller or larger than the others, but all together the slices equal 100 percent. Figure 2-2 shows a pie chart that presents the different items that compose the municipal solid waste (trash) recycled in the U.S. in 2008.
Figure 2-2: An example of a pie chart.
Illustration by Wiley, Composition Services Graphics
Bar graphs: A bar graph illustrates categories of data across a numbered scale. Bar graphs are also called histograms or frequency distributions. One axis of a bar graph represents the categories, and the other axis quantifies the different categories. Figure 2-3 shows a bar graph of the amount of trash produced by U.S. households for three different years. Each bar represents the total amount of trash for a particular year (the category of data), and the axis on the left provides a numerical scale to quantify each category. The bar graph in Figure 2-3 also presents the breakdown within each category of where the trash ends up: landfill, energy production, recycling, or compost.
Line graphs: Scientists most often use line graphs to illustrate how measurements of a particular variable or data type change over time. The line graph illustrated in Figure 2-4 shows how the amount of recycling changed each decade from 1960 to 2006.
