1. Lesson 1: Fundamental Issues in Environmental Science
It is particularly important to know the big questions in Environmental Science. One of the main things this course is about is the need to understand how the application of science is necessary to solve environmental problems. Our current president, Barak Obama, has said “Science first” when it comes to addressing environmental problems. Our previous president, George Bush, was strongly criticized for letting politics and religion drive many agendas.
The idea that science can drive all approaches on a particular issue is not entirely accurate. Since humans invented science in the first place, it is always filtered by human ideas, preconceptions, and prejudices. It is also important to understand that not all scientists agree on what the current environmental situation is, where we are going, and how best to approach the problems we need to solve.
Big Question: Why Is Science Necessary to Solve Environmental Problems?

2. How to Use the Online Lessons
The primary purpose of the online lectures are to review, reinforce, and add to material covered in the book. Material you receive in these online lessons is just as likely to be on exams as other material in the book. Some material, particularly UW, local and regional examples, and timely material, may be only on this site.
The best way for you to use the class materials is to read the each book chapter first, then view the lessons.
The primary purposes of the online lectures are to review, reinforce, and add to topics covered in the book. The material we cover in these lectures is just as likely to be on exams as material from the book. Some information, particulary UW, local, and regional examples, and timely material, may be only on this site.
Your best approach to this course is to read the book chapters first, then view the lectures. 2

3. What is "Environmental Wisdom"?
“Environmental Wisdom” must include the little and the big picture and must include people.
Visit and research the following sites:
Wikipedia article on Coffee:
CoffeeResearch.org: Coffee Production Statistics:
Where the Hell Is Matt?:
What does the information on these sites tell us about something as simple as coffee, travel, dancing, and people in the world in relationship to Environmental Science?
One of the concepts I hope to introduce to you in this class is environmental wisdom, in ways you can use it. First, the world is an incredibly interconnected place, both by its inherent nature and by human construct. You can’t separate humans from nature, and all of our concepts of the environment for this class are formed in our human minds. I don’t want to dwell on this too much, but my primary goal in this course is to allow you to approach environmental information with some useful skepticism and knowledge. Environmental "information" is constantly bombarding us, and is often used to try and manipulate us into buying something, supporting an issue, or taking a political stand. For instance, promoting certain kinds of coffee (such as shade-grown, versus sun-grown), driving an SUV through a creek to show how it can get you close to "nature," buying bamboo versus hardwood flooring, supporting the defunct Seattle Monorail, advertising investments as "green" the list goes on. What I hope most is that after you take this course you will have some of the tools to understand the basics…if not all…of the actual implications of environmental information you receive.
First, learn about how small this world really is and how we depend on disparate parts for our lives. We can use the quintessential Seattle treat, coffee, as an example of understanding the connectedness of the world. Visit the Wikipedia article on coffee to read about all you want to know about coffee as a plant, world commodity and product much of this class drinks regularly. Also, visit CoffeeResearch.org to understand just how coffee is produced (note that "Rob" is one of the major types of coffee, right behind "Arab"). Getting a cup of this drink we take for granted is actually a very complicated process, and greatly impacts people all over the world.
Finally, the following site, "Where the Hell Is Matt?," is fun. It shows us a little bit how small, and both different and similar the world is. Seattle native Matt Harding travelled to different parts of the world and had himself (and sometimes others) filmed dancing. (I wish I had thought of this myself.) It's fun to see where people actually started dancing with Matt, anywhere from Rwanda in East Africa (more on Rob’s Peace Corps experience later), to Seattle's Fremont neighborhood in front of the Troll under the bridge. The things most different are the settings and the clothing, and sometimes skin color…but dancing, like coffee, is a truly international product. ; >)
Note that you've seen me "; >) several times now. This is the keyboard, internet, computerese equivalent of a wink and a smile. Just imagine that the creaters of these online lectures are enjoying what they are presenting, and hoping you enjoy reading it. Certainly there is a lot of serious material to follow, but if we were talking together right now, we'd be laughing a bit and hoping you were too… 3 3

4. Sustainability
In the past 35 years, the number of people in the world more than doubled, from 2.5 billion to over 6.6 billion. Visit this site for current data: U.S. Census Bureau:
Our rapidly increasing population underlies all environmental problems because most environmental damage results from the very large number of people on Earth.
The basic source of all human environmental problems is the increasing human population on earth. As more people are added to the total, the finite resources of the earth become accessible to a larger number of people, who then must either use more resources or reduce their per-person use. The U.S. Census Bureau site includes current data on the U.S. and world populations. Take a bit of time to visit the site listed and explore it.

5. Sustainability Use it, but don’t use it up
Other uses of the term "sustainability":
sustainable society
sustainable economy
sustainable development
sustainable architecture
More on sustainability at Wikipedia: Sustainability:
One of the primary issues of Environmental Science is sustainability. In fact, my college (College of the Environment) has adopted sustainability as its primary theme. For humans to live sustainably, the Earth's resources must be used at a rate at which they can be replenished. There is now clear scientific evidence that humanity is living unsustainably, and that an unprecedented collective effort is needed to return the human use of natural resources to within sustainable limits.
When will the resources that sustain the over-consumption of industrialized nations be exhausted? Some resources are inherently sustainable because they are continuously produced by nature. For instance, forest products can be produced continuously as long as the soil resource that supports them is maintained. Other resources, such as oil, take very long time periods to produce naturally.
How can the nations of the world produce the goods and services needed to improve life for everyone without overtaxing the environmental systems and natural resources on which we all depend? To be truly enduring, the benefits of sustainable development must be available to all humans, not just to the members of a privileged group.

6. Earth’s Carrying Capacity
How many people can Earth sustain?
Carrying capacity is usually defined as the maximum number of individuals of a species that can be sustained by an environment over the long term.
A major principle of the sustainability of Earth (or of any system, in fact) is the carrying capacity of that system. "Carrying capacity" is defined as the maximum number of individuals of a species that can be sustained by an environment over the long term--that is, not depleted; for example, in a fishery, if we don’t harvest more than the carrying capacity, the fishery should be sustainable. Of course, changing parts of the system can change its carrying capacity. Earth’s human carrying capacity depends in part on how we want to live, and how we want those who follow us to be able to live.

7. A Global Perspective Today our actions are experienced worldwide.
Life makes Earth’s environment unlike that of other planets.
The Gaia hypothesis proposes that the global environment has been profoundly changed by life throughout the history of life on Earth, and that these changes have improved the chances that life on Earth will continue.
See the Wikipedia article: Think Globally, Act Locally.
It has been said that people need to “Think Globally, and Act Locally.” Exactly what this might mean in any individual situation will vary. Basically, it is important to be able to picture the impact of your individual actions on the overall Earth, and also to be able to scale up those actions to your family, community, and even larger scales. Advanced additional reading on the idea can be found at:

8. Cities Affect the Environment
We are becoming an urban species, and our effects on the environment are more and more the effects of urban life.
We must look more closely at the effects of urbanization.
Even as this happens, we cherish the concept of time in non-urban environments more than ever.
One mistake many people make in studying and trying to understand environmental science is to try to separate people from the concept of the environment. The idea is to have a "wild, natural environment" separate from a "human-influenced" one, usually with the idea that the natural one is pristine and wonderful, and the human one being messed up in various ways. Think of driving from downtown Seattle where nearly every area is built up and there are few species except humans and those like pigeons and ants that live off humans.
The term "wilderness" is often applied to the wildest environment, and we are taught that it is special. I don't disagree, and I often gravitate toward these areas myself (particularly toward the end of a quarter of teaching ESRM100). To understand "wilderness," however, you need to understand that it is a human concept as well. As our lives get more complicated, we are becoming more Earth-centered, hoping to spend more time in nature for recreation and spiritual activities.
If you really want a heavy dose of the concepts of "wilderness," I suggest a good read: Wilderness and the American Mind by Roderick Frazier Nash, published by Yale University Press. Also, Rebecca Solnit's book Savage Dreams also considers the concept of wilderness as a European construction. Indigenous peoples, she says, don't recognize the concept: for them, the "wilderness" is just home.
Professor Darlene Zabowski and I teach a course "Wildland Soils, ESRM416" where part of the class is to explore wilderness areas in the North Cascades. (The class is very special, but limited to 10 students because of wilderness regulations.) One of my goals is to teach a course on "Wilderness" in the near future that all UW students would have a chance to take if they want to.

9. People and Nature
“Principle of environmental unity”: everything affects everything else
We depend on nature for many natural service functions
For a lot more information (and propaganda) on the impacts of overconsumption, see the International Buy Nothing Day Web site:
So, let us try as much as possible to find the connection between what we will sometimes define as different environmental systems. The principle of environmental unity is very important to integerate into our thinking about enviromental science. We simply cannot live as humans anywhere on the Earth without having an impact on the environment, and our goal should be to live well even as we use lightly from the environment. As Americans we are harangued constantly, from the time we can barely understand words, to "Buy, Buy, Buy." We are currently (2009) being asked to buy our way out of the current slump in the economy. Consumption of resources always has an impact.

10. Science and Values
Before we decide what kind of environment we want, we need to know what is possible.
Science is a process of discovery.
Sometimes changes in ideas are small.
Sometimes a science undergoes a fundamental revolution in ideas.
Yes, using resources from the environment does affect it, but the reason we need science now is to help us understand how. We have largely used science in the past as a way to increase our ability to use natural resources (think machines, transportation, and so on.) We can also use science in other ways, particularly to increase efficiency.
We can use environmental science potentially as a way to help us live well but with less negative impact, by using fewer resources and producing less waste. Studying environmental science will not only tell us about where resources are and how we use them, but also allow us to develop more efficient systems.

11. Science is one way of looking at the world.
It begins with observations about the natural world.
From these observations, scientists formulate hypotheses that can be tested.
Science does not deal with things that cannot be tested by observation, such as the following:
the ultimate purpose of life;
the existence of a supernatural being; or
standards of beauty or issues of good and evil.
Ideas are scientific if it is possible to disprove them.
In order to understand our environmental, we need to study it from a scientific perspective: that is, to apply scientific principles to our study. In this way, we advance our knowledge of environmental science. Science deals with things that can be disproven; ideas are scientific only if it is possible to disprove them. The most effective scientists rely on critical and disciplined thinking using intellectual standards, effective communication, clarity, and commitment to developing scientific knowledge and skills. These are skills that can be taught and learned.
It is unfair to define good scientists any further than this. For instance, it is often said that environmental scientists should reduce their own impact on the environment. That is a worthy goal for anyone, but someone can be an excellent environmental scientist even if they use far more than their share of the Earth’s resources.
It is a complete fallacy, also, to say that Science disproves the existence of God (or whatever name we use to refer to a supernatural being). One of the wonders of being an environmental scientist is to discover a tiny part of how the world works (or doesn’t), even as you realize that most of the functions of the world will remain a mystery to you. This may or may not change how you live your own life. It is entirely possible to keep an open mind searching for what you can understand through science and advance scientific thought even as you might hold convictions that can’t be approached through science. Charles Darwin is a good example (see Of course, Rob Harrison, as a soil scientist, most admires Charles Darwin because of his groundbreaking research on worm composting. ; >) ; >) ; >) ; >) see

12. What is Environmental Science?
A group of sciences that attempt to explain how life on Earth is sustained, what leads to environmental problems, and how these problems can be solved.
Often linked with nonscientific fields that have to do with how we value the environment (such as Deep Ecology).
Deals with many topics that have great emotional effects on people.
Earlier, we defined "environmental science" specifically in science terms. However, this is not how the term is commonly used. Society often links nonscientific fields and values with the term "environmental science," probably because the topics of environmental science have deep emotional impacts on many people, often akin to religious thought. A good example is the Deep Ecology movement Biodynamic Farming ( is another example; this includes very effective farming techniques (such as re-use of organic waste material through composting), with such ineffectual practices as burying silica-filled cow horns in the middle of fields during the spring equinox and taking them out at the fall equinox.
Its easy to understand the attraction behind many of these non-scientific ideas that are melded into environmental science. It is also important, as you study environmental science, that you be able to separate what is supported by science from what is not.

13. Placing a Value on the Environment
Utilitarian justification
values the environment it is useful economically or for survival.
Ecological justification
Values the larger life-support functions of the environment.
Aesthetic justification
values beauty.
Moral justification
based on one’s view of right and wrong, and extending inherent rights beyond humans.
If we are to study environmental science effectively, we need to have a framework for valuing the environment. Values can be utilitarian (for example, economic), ecological (how parts of the environment function), aesthetic (how the environment affects our humanity and soul), or moral (whether or not we believe that nature has “rights” in the same way as humans).

14. Solving Many Environmental Problems Involves Systems and Rates of Change
A system is a set of parts that function together to act as a whole, like a city (streets, buildings, sewer systems) or a river (water sources, animals and plants in and along the river.
We also need to start thinking of the environment and solving environmental problems as the study of systems. Like your own body, the environment is a system. Your body needs food (which would be an input), which you digest for energy; environmental systems also respond to inputs of energy. The oxygen in the air you breathe is also an input. You also need to eliminate the bioproducts of respiration and digestion, which would be outputs, not always pleasant ones ;>). The carbon dioxide you exhale is also an output. Likewise, an environmental system has outputs.
These systems also have feedback, since the output of one system also serves as input for another, and leads to further changes in the other system. For instance, the CO2 you breathe out can become a raw material that plants use in photosynthesis to produce food, fiber, or wood, which you, in turn, might use. Negative feedback occurs when an increase in output leads to a decrease in the output of the system, and positive feedback occurs when an increase in output leads to a further increase in the output of the system.

15. Positive Feedback: Off-road Vehicles (ORVs) and Erosion
Here is an example of positive feedback on the rates of erosion of dunes. The use of off-road vehicles or “ORV’s” leads to a loss of vegetation (the tires kill it), which leads to erosion forming gullies and ruts, which can lead to further loss of vegetation through additional erosion. As the ORV’s widen their path they can exacerbate this problem, which leads to more erosion. Erosion is the output from the system.

16. Some situations involve both positive and negative feedback
Example: changes in human populations of large cities
Here is a system that has both positive and negative feedbacks. Which kind of feedback is more desirable? For natural systems, feedback and processes aren’t considered good or bad, they just are. Humans place values on these according to our own wants and needs. For instance, we all want to live, but like the city population model shown in the slide, human population itself can have negative impacts on other humans. For most of human history, strong negative feedback limited growth of the human population. Technology has changed a lot of that.

17. Exponential growth
Exponential growth is an important outcome of positive feedback
Exponential growth is incompatible with sustainability
We’ll consider human population in great detail in Lesson 2, but we can use it as an example of feedback here. For instance, most humans reproduce and produce more humans. If we remove constraints on the growth rate, we see an exponential increase based purely on ability to reproduce, which is substantial and not often realized. Human population increase over the last few hundred years is a great example of both a positive feedback and a process that can’t be continued indefinitely in a finite world.
If it were possible for human growth to continue to occur, say, at the growth rate of the country of the Maldives (in 2008, the rate was 5.57 % per year, the world’s fastest-growing country according to the CIA “factbook”), the population would double each about every 10 years. If this growth rate continued until the year 2269 (it won’t), only 260 years from now, each human would have about 1 meter x 1 meter of room on the Earth’s land. Matt the dancer (see slide 3) could dance nearly anywhere in the world and have people with him. Fortunately, this won’t happen.

18. Environmental Unity
It is impossible to change only one thing; everything affects everything else
Changes in one part of a system often have secondary and tertiary effects within the system and effects on adjacent systems
See Wikipedia: Butterfly Effect and Wikipedia: A Sound of Thunder. Also see "The Butterfly Effect—Real?"
One of the most important principles we need to consider in environmental science is that many of these systems are interconnected. For instance, human population growth is connected to many other things than just the genetic potential of humans to reproduce. It is limited by resources, social pressures, and anything that kills humans before they have the chance to have children. However, it is possible to take things a little too far. The idea that a butterfly beating its wings in China can cause cyclones is interesting, but perhaps a bit overstated. See Such “tiny cause has tremendous effect” has been the subject of a lot of speculation, including in a short story by Ray Bradbury “A sound of thunder”
There is an interesting discussion of how far Environmental Unity relative to the “butterfly effect” at
We will find in nature that environmental systems often have complexity, and that sometimes a complex system relies on a single part for much or most of its function. For instance we will learn about “Keystone species” in later chapters. These are species (often food species) without which entire ecosystems can drastically change. However, we also find redundancy in many ecosystems, and we see that more than one species performs an essential service. For instance, apple trees in my yard are cross-pollinated by honey bees, mason bees, various wasps, and perhaps a bit by wind.

19. Changes and Equilibrium in Systems
When the input to a system is equal to the output, the system is said to be in a steady state
Steady state is a dynamic equilibrium because something is still happening
Some systems can appear to be unchanging over time periods ranging from short to long. The term steady state applies to a stable condition that does not change over time, or in which change in one direction is continually balanced by change in another. Steady states can be in dynamic equilibrium, because the system is not just sitting still; something is happening. Material or energy is entering and leaving the system in equal amounts. An approximate steady state may occur on a global scale, such as in the balance between incoming solar radiation and outgoing radiation from Earth (actually, Earth seems to be warming), or on the smaller scale of an environmental science class, where new students replenish the class each quarter. Of course, each of you is unique, so this quarter’s ESRM100 is truly an exception to any ecological principle ; >)

20. If input is less than the output, the storage compartment will shrink
Groundwater extraction
If input exceeds
output, the storage
compartment will
expand
Groundwater
pollution
Here are examples of how the system's equilibrium can change.
When the input is less than the output, the amount of material in the storage compartment shrinks. For example, if a resource, such as groundwater, is consumed faster than it can be replaced by nature or by people, it may be used up. When input exceeds output, the amount of material in the storage compartment will expand. An example is the buildup of the pesticide DDT in bald eagles by bioaccumulation.
Residence time is also important. By using rates of change or input-output analysis of systems, we can calculate an average residence time for material moving through a system—that is, how long it takes for that particular material to be cycled through the system. Average residence time has important implications for environmental systems. In a system such as a small lake with an inlet and an outlet, water has a short residence time. This makes the lake especially vulnerable to change—if, for example, a pollutant is introduced. On the other hand, the pollutant soon leaves the lake. In large systems, such as oceans, water has a long residence time. This makes such systems much less vulnerable to quick change. However, once polluted, they are difficult to clean up.

21. To effectively manage natural systems, we need to understand:
the types of disturbances and changes that are likely to occur
the time periods over which changes occur
the importance of each change to the long-term productivity of the system.
When you have system input and output, you have a way of interpreting changes that may affect systems. Let's dispense here with the idea that has been used and defended in the study of our natural environment: that if natural systems are not disturbed by people, they will tend to persist in a steady state, sometimes called the “balance of nature.” The balance of nature may exist for different periods, but it is the exception in many systems, not the rule. We find that a steady state seldom happens. Most systems are disturbed, not only by people, but also by natural events, such as floods, wildfires, volcanoes (such as Mt. St. Helens), and earthquakes (think of the Seattle fault), tsunamis, and so on that change systems over time. Studies of systems such as forests, rivers, and coral reefs find that disturbances due to natural events such as storms, floods, and fires are often required for the maintenance of those systems. Systems change naturally, and if we are going to manage systems for different goals, we need a better understanding of the types of disturbances and changes that are likely to occur, the time periods over which changes occur, and the importance of each change to the long-term productivity of the system.

22. Biota: Biosphere and Sustaining Life
Biota: all living things (animals and plants, microorganisms) within a given area
Biosphere: the region of Earth where life exists
What is needed to sustain life?
there must be several species within a system that includes air and water to transport materials and energy – an ecosystem
Earth as a planet has been profoundly altered by the life that inhabits it. Earth’s air, oceans, soils, and sedimentary rocks are very different from what they would be on a lifeless planet. Imagine what Seattle would be like, for instance: pretty much just rocks. There would be an atmosphere, but it would have little molecular oxygen in it--certainly not enough to sustain the ESRM100 class during even one of its exams (check syllabus for schedule) ; >). That life that began on Earth billions of years ago is now part of the ecosystem here, and greatly controls the composition of the current air, oceans, and sediments.

23. Ecosystems
A community of organisms and their local nonliving environment in which matter (chemical elements) cycles and energy flows
Vary in size, from the smallest puddle of water to a large forest, or the entire global biosphere
Ecosystem borders may be clearly or vaguely defined
Ecosystems are communities of organisms and that community’s local nonliving environment, in which matter (i.e. chemical elements) cycles and energy flows. Life on Earth is composed of ecosystems, not of individual organisms or populations or single species. Ecosystems vary greatly in size (from miniscule to global) and composition (from ice on Mt. Rainier, for example, to water in Lake Lenore--a prime fishing lake of mine--to sandy scrubland in the Palouse). The number and kinds of species and the kinds and relative proportions of nonbiological components also vary greatly. Sometimes the borders of an ecosystem are well defined (for example, a lake), and in other places they are vague, as in the gradual shift forest as we move from the west side of the Cascades toward the east, into the rain shadow of, say, the area east of Lake Chelan. What all ecosystems have in common is not the physical structure of size, shape, and variations of borders, but the processes of flow of energy and the cycling of chemical elements within them.

24. Environmental characteristics that make solving problems harder
Lag time is the time between a stimulus and a system’s response to that stimulus
If there is a long delay between stimulus and response, then the resulting changes are much more difficult to recognize
Global environmental problems such as global warming are particularly difficult for society to deal with because of three features of the current Earth system: (1) exponential population growth and the positive feedback that accompanies that growth, (2) long lag times of decades or more between the input (for example of CO2 or methane into the atmosphere) and responses to that input, and (3) the potential for some events to produce irreversible changes. Let’s look at each of these in turn.
Lag time is the time between a stimulus and a system’s response to that stimulus. If the lag time is very short, the response is easier to identify. For example, the release of a toxic gas from a chemical plant may have almost immediate consequences to people living near the plant. If there is a long delay between stimulus and response, then the resulting changes are much more difficult to recognize. When we are dealing with biological resources, a long delay in seeing the results of a population’s exponential growth may lead to overshoot, when the carrying capacity is exceeded.

25. Exponential Growth and Long Lag Time
Exponential growth and long lag time may allow a population to eventually exceed the carrying capacity, resulting in overshoot and a decline collapse in the population.
Some environmental changes may be irreversible over time periods of hundreds or thousands of years
As we noted earlier, the consequences of exponential growth and its accompanying positive feedback can be dramatic, leading to incredible increases in whatever is being evaluated or measured.
Not all adverse effects of environmental change lead to irreversible consequences, but some certainly do, and these can be serious problems. By “irreversible consequences” we mean consequences that may not be easily rectified, even within a few human lifetimes. A good example is soil erosion, or the taking of plants and animals that have very long lifetimes (such as Galapagos tortoises). For soil (Rob Harrison’s specialty) there may be a long lag time before the soil no longer has enough nutrients to produce a crop. At that point, it may take hundreds or thousands of years for new soil to form. Similarly, it may take hundreds of years for long-lived (and usually slowly reproducing) species such as Galapago’s tortoises or blue whales to recover.

26. Ecological Footprint
Ecological footprint - the total area each person requires based on the resources used and the waste produced.
We may be consuming about 20% more of Earth’s biological productivity than is replaced each year.
Take the Ecological Footprint Quiz to determine your own ecological footprint.
You may have heard the term “carbon footprint” or “ecological footprint.” Ecological footprint is the total area each person requires based on the resources he or she uses and the waste he or she produces. The graph shows trends in human use of Earth’s biological productivity for the past 40 years. It suggests that in the mid-1980s, we passed the point where people’s demand for biological resources just balanced the amount that could be naturally replaced. At that point, after a long lag time of exponential growth in the use of biological resources, overshoot began. Of course, previous scientists have suggested that we passed this point as much as hundreds of years ago.
Take the Ecological Footprint Quiz to determine your own ecological footprint. It's interesting to note that changes in your lifestyle can increase or reduce the footprint, but the model assumes that if you are an American, you’ll likely have a higher footprint than people living the same lifestyle in other countries. Try keeping everything the same, but change the country to India, for instance. This can be a problem with models…the basic underlying assumptions may not always be correct.

27. The Precautionary Principle: When in Doubt, Play It Safe
It can be difficult to prove with absolute certainty how human activities lead to local and global environmental problems.
When there is a threat of serious environmental damage, we should not wait for certain scientific proof before taking steps to prevent potential harm.
How much proof do we need before acting?
We need to examine the benefits and costs of taking a particular action versus taking no action.
The Precautionary Principle is a proactive tool.
More information on the Precautionary Principle.
Even with careful scientific research, it can be difficult to prove with certainty how relationships between human activities and other physical and biological processes lead to local and global environmental problems, such as global warming, depletion of ozone in the upper atmosphere, loss of biodiversity, endangered species, and declining forest and fishery resources. For this reason, in 1992 the Rio Earth Summit on Sustainable Development listed as one of its principles what we now define as the Precautionary Principle. Basically, it says that when there is a threat of serious, perhaps even irreversible, environmental damage, we should not wait for scientific proof before taking cost effective, precautionary steps to prevent potential harm to the environment. There will always be arguments over what constitutes sufficient scientific knowledge for decision-making. Nevertheless, the Precautionary Principle, even though it may be difficult to apply, is becoming a common part of environmental analysis with respect to environmental protection and environmental health issues.
What do you think about this?

28. Chapter 1: Fundamental Issues in Environmental Science
Questions? your TA.
Please do contact us if you have any questions 28