There are some recurring themes in the book you are about to use to learn about the environment. Human population growth is in the exponential phase, and much of the change in the environment is driven by this massive growth. The world is becoming more urbanized, so problems must be solved in urban settings, not always in the wilderness. Sustainability (using natural resources at a rate that allows sufficient time for replenishment) is an unrealized goal, but a worthy one. The environmental problems are global in scale and this requires worldwide cooperation. Human values and knowledge play important roles in the environmental conflicts; knowledge or scientific data can only suggest what the alternative solutions are, but which alternative we choose is still a matter of values or cultural preference.

• Sustainability is the ability of an ecosystem, population, or other system to perpetuate its functions or production indefinitely even with removal of environmental resources or harvests by humans.
• We can differentiate four types of sustainability:
• 1) sustainable resource harvest;
• 2) sustainable ecosystem function;
• 3) sustainable economy;
• 4) sustainable development.
• Although rapid changes are occurring, most American businesses plan with economic sustainability in mind (that is, they turn a profit or go out of business), but often do not consider the other three types of sustainable practices.

• The carrying capacity refers to the maximum number of individuals of a species that can be sustained by an environment without decreasing the capacity of the environment to sustain that same number of individuals in the future.

• This number is not known for certain and can only be estimated for humans. Some conservative estimates suggest that we have already surpassed the carrying capacity; and that in the future we shall experience declines in human numbers.
• Most population experts suggest that the carrying capacity may be in the range of 12-13 billion people.
• Still others suggest that the carrying capacity is far greater than this, but we have not yet developed the technology to allow us to reach such high levels.
• The quality of life that people can expect will almost certainly decline with increased population size. It is clear that there will be some limit to growth of the human population, but the exact population size at which the Earth's carrying capacity will be reached is not known for certain.

• Yes. The recent famines in Somalia and other African nations are the best indicator that in some regions of the world, the human population has reached the environment's carrying capacity.
• Population growth in sub-Saharan Africa has begun to exceed food production (i.e., per capita food production is declining).
• Interestingly, the human population is still rising in nations affected by the famines, largely because of the reproductive inertia of human population growth, the population's willingness to live in such poor environmental conditions, and the food and humanitarian assistance provided by governments in neighboring regions (such as the USA and European countries).
• It is nearly certain that there will be continued declines in per capita food production in these nations. Political unrest, starvation, and armed conflict will affect this region for some years to come, until the population starts to decline.

• The "Gaia Hypothesis" is really a concept that the environmental conditions found on the Earth (such as the oxygen-dominated atmosphere that is produced by plant photosynthesis and is absent from other planets in the solar system) are caused by the symbiotic interactions of the organisms on Earth and are self-regulating.
• Central to this concept is the idea that all species on the planet are interacting indirectly as a "superorganism" and that ecological damage in one part of the Earth will be reflected elsewhere.
• This concept of the Earth as a superorganism has been suggested by James Lovelock and Lynn Margulis (although they were not the first to propose such a concept).
• Gaia , who was the Goddess of the Earth in Greek mythology and roughly equivalent to our idea of "Mother Earth", embodies such a superorganism concept, although such a mythical figure doesn't really exist.
• Some consider the name "Gaia" unscientific and this "hypothesis" to be untestable, but the concept of self-regulation of complex systems such as the Earth's Biosphere is certainly a scientifically plausible idea.
• Self-regulation means that conditions (such as temperature) on Earth appear to be controlled or held within bounds by organisms on Earth so that these conditions remain more or less constant over time.
• If the conditions are disturbed, they tend to return to the equilibrium due to the influence of the organisms, and hence the Earth can be self-regulating.
• Increasingly, the "Gaia Hypothesis" worldview of global interactions suggests that solutions to environmental problems are global in scale, comprised of many local ecological disruptions that accumulate globally. Thus, both local and global issues are related and solutions must be sought across all spatial scales.

• The movement of people from small towns and rural areas to large cities is called urbanization.
• Developed countries like the USA have 75 % of the population living in urban areas, whereas undeveloped nations such as Ethiopia have only 34 % living in cities.
• The environmental impacts associated with urban areas extend far beyond their borders, because all food and water must be imported into cities.
• This increases the environmental "footprint" of an urban population greatly, because there are many environmental costs (such as increased air and water pollution, loss of wetlands and farmlands, and the loss of wildlife habitat) associated with the intensive production and transportation of food to cities.
• Compounding this is the tendency of city dwellers to use far more food, water, and other natural resources per capita than non-city dwellers.
• Thus, environmental disruption happens more rapidly and over a greater area in a highly urbanized country than it does in a largely rural country.

• The need for food, shelter, and economic goods all arise from environmental resources. People who use this sort of justification for protecting the environment value resources based on market economics. (e.g., the value of forest is simply equal to the value of the timber, paper and wood products that can be made from it and sold).

• When an environmental resource performs a role or function in an ecosystem that is not directly beneficial to an individual human in an economic sense, it may be desirable to protect it in order to preserve that function for the ecosystem by using an ecological justification.
• An example of this would be the water purification function that wetlands are capable of performing. Ecological justification is often required to protect wetlands. The economic value to humans in the form of reduced sewage treatment costs can be calculated, but this cost savings is often not considered in environmental decision-making because an individual owner of the wetland receives none of that savings as income.

What is an aesthetic justification for protecting the environment?

• Some environmental resources produce economic income just because they are pleasant places to visit or provide a scenic vista.
• A good example is Yosemite National Park, because the dramatic scenery and wildlife attract thousands of visitors each year. The economic value produced by the park is a utilitarian justification, but the beauty of nature has always been valued by people independently of the economic income. Yosemite was not set aside as a national park because it would make money for the US government and private citizens living nearby, but because it was a beautiful place to experience the wonders of nature.
• Natural resources such as Yosemite are often protected using an aesthetic justification.

• Some people value environmental resources solely because of their belief that they should always be present on Earth no matter what economic value they have.
• For example, there was great debate a few years back about whether we humans should destroy the last known samples of the human smallpox virus, because it had been completely eliminated in nature. The destruction would have caused the complete extinction of a disease-causing virus. It was decided to protect this species in part because of a moral justification, because all species have a moral right to exist, even species that act as parasites and predators on humans.
• The discipline of environmental ethics focuses on such questions.

• Where in your city or on your campus do you see a choice between the old ways of doing things (non-sustainable use of resources) and the alternative sustainable approaches suggested in this chapter?
• Does your college have a recycling program?
• Do you recycle?
• Does your campus use recycled paper?
• Are you attempting to use recycled papers, reduce your paper use?
• Do you conserve fossil fuels by riding a bike or walking instead of driving?
• Does your city or campus support a bus system (buses are more sustainable than cars, because they carry more people over more miles per gallon of fuel than automobiles)?
• Please respond to these questions or send your thoughtful examples and comments to:

• Erlich, P. 1968. The Population Bomb. Ballantine Books, New York, NY.
• Lovelock, J. 1979. Gaia: A New Look at Life on Earth. Oxford University Press.
• Schneider, S. H. and P. J. Boston. 1991. Scientists on Gaia. The MIT Press, Cambridge Massachusetts. 443 pp.

• Note: If any of these links are not working, please see if alternative links are available at the Ecolink Update Site.

Ecotest Online

a) sustainable resource harvest

b) sustainable ecosystem function

c) sustainable economic principles

d) sustainable development

a) 2.7 billion

b) 2.7 million

c) 5.7 million

d) 5.7 billion

e) 5.7 trillion

a) We know for certain what the carrying capacity for the human population on Earth is

b) The carrying capacity is the maximum number of individuals that can be sustained in an area without decreasing the number of individuals in the future that can be supported in the same area

c) The carrying capacity for humans on Earth has been exceeded

d) The human population is far below the carrying capacity for humans on Earth

e) The carrying capacity for people on Earth is 5.7 billion people

a) Famines in parts of Africa

b) Political unrest, revolutions, and armed conflict in the Middle East

c) The massive decrease in the birth rate and increase in the death rate in Africa

d) Population estimates that suggest a population of 11.4 Billion people in 2040.

e) There is no evidence that the carrying capacity has been exceeded in any region.

a) is a concept of the Earth as a self-regulating "super-organism"

b) suggests that there is a Goddess of the Earth named Gaia

c) is a hypothesis that can be rigorously tested by scientific experimentation

d) states that "Mother Earth" controls the biosphere's ecosystems

e) suggests that the Earth can be damaged and it will "heal" itself

a) 25 %

b) 50 %

c) 75 %

d) 10 %

a) The loss of wetlands

b) The loss of farmlands

c) The increase in air pollution

d) The increase in water pollution

e) All of these are correct

a) "The natural balance of the food web is changed when excessive fishing is allowed. In order to protect the entire marine ecosystem, including whales and dolphins, we should conserve fish stocks."

b) "Many people come to the coast to fish and they spend $ 1 million each year on food, drinks, ice, boats, fuel, and fishing equipment. We want to protect fish stocks so that these people will come back year after year."

c) "I have visited the public aquarium and I like to watch the fish. I think that these fish populations must be protected."

d) "I am opposed philosophically to the practice of fishing. It is not humane to the fish."

a) Ecological concerns

b) Utilitarian concerns

c) Moral and ethical concerns

d) Aesthetic concerns

e) All of these are correct

a) The clear-cutting of old growth forests in the Pacific Northwest

b) The destruction of wetlands to be replaced by a sewage treatment facility

c) The construction of aquaculture ponds in mangrove ecosystems

d) The harvest of salmon from the Columbia River by a small population of Native Americans in that region using traditional methods of capture