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Transcript
CHAPTER 36: ENVIRONMENTAL CONCERNS
LECTURE OUTLINE
36.1 Human Use of Resources
A resource is anything from the biotic or abiotic environment that helps meet certain basic human
needs. Nonrenewable resources are limited in supply. Renewable resources are not limited in
supply. A side effect of resource consumption can be pollution.
Land Use Change
People need a place to live.
Beaches and Human Habitation
At least 40% of the world population lives within 100 km of a coastline.
Beach Erosion
An estimated 70% of the world’s beaches are eroding. Humans carry on
activities that contribute to the rising of the seas and erosion of beaches.
Coastal Pollution
The coast is particularly subject to pollution.
Semiarid Lands and Human Habitation
Desertification is the conversion of semiarid land to desertlike conditions.
Tropical Rain Forests and Human Habitation
Deforestation, the removal of trees, has long allowed humans to live in areas
where forests once covered the land. Tropical rain forests are subject to
desertification because soil in the tropics is thin and nutrient-poor.
Loss of Biodiversity
Development in tropical rain forests leads to loss of biodiversity.
Water
In some areas of the world, people do not have ready access to drinking water, and if they
do, the water may be impure.
Increasing Water Supplies
Certain areas of the world do not have a renewable supply of water.
Dams
Dams catch precipitation runoff, provide water for land irrigation, and
generate electricity. They are not without drawbacks, however.
Aquifers
To meet their freshwater needs, people are pumping vast amounts of
water from underground aquifers.
Environmental Consequences
Removal of water is causing land subsidence and saltwater intrusion into
the aquifers.
Conservation of Water
Reusing water and adopting conservation measures could help the world’s
industries cut their water demands.
Food
Food comes from three activities: growing crops, raising animals, and fishing. The
increase in the food supply has largely been possible because of modern farming
methods, which unfortunately include some harmful practices.
Soil Loss and Degradation
When topsoil is lost, farmland loses its productivity. Salinization is the
accumulation of mineral salts due to evaporation of excess irrigation water.
Green Revolution
The green revolution helped the world food supply keep pace with the rapid
increase in world population but most of these plants required high levels of
fertilizer, water, and pesticides.
Genetic Engineering
Genetic engineering can produce transgenic plants with new and
different traits. Genetically engineered crops could result in still another
green revolution.
Domestic Livestock
In more-developed countries, many people tend to have more than enough
protein in their diet. Raising livestock uses up an excessive amount of fossil fuel,
fertilizer, water, herbicides, and pesticides.
Fishing
The result of an increased number and efficiency of fishing boats was a severe
reduction in fish catch. Modern fishing practices negatively impact biodiversity.
Energy
Modern society runs on various sources of energy.
Nonrenewable Sources
Most of the world’s energy comes from fossil fuels and nuclear power, both
nonrenewable energy sources.
Fossil Fuels and Global Climate Change
The burning of fossil fuels results in an increase in greenhouse gases and
global warming.
Renewable Energy Sources
Hydropower
Hydroelectric plants convert the energy of falling water into electricity.
Geothermal Energy
The Earth has an internal source of heat that can be harnessed.
Wind Power
Wind power is expected to account for a significant percentage of our
energy needs in the future.
Energy and the Solar-Hydrogen Revolution
We now have better ways to capture solar energy. Scientists are
investigating the possibility of using solar energy to extract hydrogen
from water via electrolysis. The hydrogen can then be used as a cleanburning fuel.
Minerals
Minerals are nonrenewable raw materials in Earth’s crust that can be mined and used by
humans. Nonrenewable resources are subject to depletion.
Synthetic Organic Compounds
Synthetic organic compounds have a detrimental effect on the health of living things.
These are produced during the production of various products humans consume.
Wastes
Wastes are generated during the mining and manufacturing process. These wastes can
lead to pollution and human illness.
Endocrine-Disrupting Contaminants
Chemicals from pesticides, herbicides, plastics, food additives, and personal
hygiene products can affect the endocrine system.
Sewage
Raw sewage causes oxygen depletion in lakes and rivers. Human feces can
contain pathogenic microorganisms.
Industrial Wastes
Industrial wastes can include heavy metals and chlorinated hydrocarbons. These
wastes enter bodies of water and are subject to biological magnification.
36.2 Impact on Biodiversity
Biodiversity can be defined as the variety of life on Earth. We are presently in a biodiversity
crisis—the number of extinctions expected to occur in the near future is unparalleled in Earth’s
history.
Habitat Loss
Human occupation of the coastline, semiarid lands, tropical rain forests, and other areas
are the most important cause of the loss of biodiversity.
Exotic Species
Exotic species are nonnative members of an ecosystem. Humans have introduced exotic
species by the following means:
Colonization
Europeans, in particular, brought various familiar species with them
when they colonized new places.
Horticulture and Agriculture
Some exotics now taking over vast tracts of land have escaped from
cultivated areas.
Accidental Transport
Global trade and travel accidentally bring many new species from one
country to another.
Exotics on Islands
Islands are particularly susceptible to environmental discord caused by the
introduction of exotic species.
Pollution
Pollution brings about environmental changes that adversely affect the lives and health of
living things.
Acid Deposition
Acid deposition decimates forests and lakes.
Eutrophication
Lakes are under stress due to overenrichment.
Global Warming
Global warming is expected to have many detrimental effects.
Ozone Depletion
The ozone shield protects Earth from harmful ultraviolet radiation.
Organic Chemicals
Endocrine-disrupting contaminants affect the endocrine system and
reproductive potential of animals.
Overexploitation
Overexploitation occurs when the number of individuals taken from a wild population is
so great that the population becomes severely reduced in numbers. For example, a
marine ecosystem can be disrupted by over fishing.
Disease
Wildlife is subject to emerging diseases just as humans are.
36.3 Value of Biodiversity
Biodiversity is a resource of immense value.
Direct Value
Various individual species perform services for human beings.
Medicinal Value
Most of the prescription drugs used in the United States were originally derived
from living organisms.
Agricultural Value
Crops such as wheat, corn, and rice are derived from wild plants that have been
modified.
Consumptive Use Value
Most freshwater and marine harvests depend on wild animals.
Indirect Value
These services are said to be indirect because they are pervasive and not easily
discernible.
Biogeochemical Cycles
The biodiversity within ecosystems contributes to the workings of the various
biogeochemical cycles.
Waste Disposal
Decomposers break down dead organic matter and other types of wastes.
Provision of Fresh Water
The water cycle continually supplies fresh water to terrestrial ecosystems.
Forests and other natural ecosystems soak up water and then release it at a
regular rate.
Prevention of Soil Erosion
Intact ecosystems naturally retain soil and prevent soil erosion.
Regulation of Climate
Globally, forests ameliorate the climate because they take up carbon dioxide and
release oxygen.
Ecotourism
In the United States nearly 100 million people enjoy vacationing in a natural
setting.
36.4 Working Toward a Sustainable Society
A sustainable society would be able to provide the same goods and services for future generations
of human beings as it does now and biodiversity would be conserved.
Today’s Society
Today’s society has several characteristics that indicate it is not sustainable.
Characteristics of a Sustainable Society
Natural ecosystems offer clues as to what a sustainable human society would be like,
including the use of renewable solar energy and material recycling.
Assessing Economic Well-Being and Quality of Life
The gross national product pertains solely to economic activities and does not take into
consideration any activities that are socially or environmentally harmful.
Measuring Nonmonetary Values
Measures that include noneconomic indicators are probably better than the GNP
at revealing our quality of life. Such indices include the Index of Sustainable
Economic Welfare and the Genuine Progress Indicator. Other values to consider
include:
Use Value
The actual price we pay to use or consume a resource.
Option Value
Preserving options for the future.
Existence Value
Saving things we might not realize exist yet.
Aesthetic Value
Appreciating an area or creature for its beauty and/or contribution to
biodiversity.
Cultural Value
Factors such as language, mythology, and history that are important for
cultural identity.
Scientific and Educational Value
Valuing the knowledge of naturalists, or even an experience of nature, as
types of rational facts.