Chapter 30

Summary		Questions		Media Resources
30.1 The world's human population is growing explosively.
• Population growth rates are declining throughout much of the world, but still the human population increases by 77 million people per year. At this rate, the global population will double in 39 years. • An explosively growing human population is placing considerable stress on the environment. People in the developed world consume resources at a vastly higher rate than those in the developing world. Such high levels of consumption are not sustainable and are as important a problem as global overpopulation.		1.  Why, in some respects, is the population size of the developed world more of a consideration in discussing resource use than the population of the developing world?
30.2 Improvements in agriculture are needed to feed a hungry world.
• Much current effort is focused on improving the productivity of existing crops, although the search for new crops continues.		2.  What three species supply more than half of the human energy requirements on earth? How many plants supply over 90%?		•Food Production
30.3 Human activity is placing the environment under increasing stress.
• Human activities present many challenges to the environment, including the release of harmful materials into the environment. • Burning fossil fuels releases carbon dioxide, which may increase the world's temperature and alter weather and ocean levels. • Release of pollutants into rivers may make the water unfit for aquatic life and human consumption. • Release of industrial smoke into the upper atmosphere leads to acid precipitation that kills forests and lakes. • Release of chemicals such as chlorofluorocarbons may destroy the atmosphere's ozone and expose the world to dangerous levels of ultraviolet radiation. • Cutting and burning the tropical rain forests of the world to make pasture and cropland is producing a massive wave of extinction.		3.  What problems must we master before nuclear power's full potential can be realized? 4.  Why were chlorinated hydrocarbons banned in the United States? Why can you still find them as contaminants on fruits and vegetables? 5.  How does acid precipitation form? Why has it been difficult to implement solutions to this problem? 6.  What is the ozone layer? How is it formed? What are the harmful effects of decreasing the earth's ozone layer? What may be the primary cause of this damage?		•Global Warming •Bioaccumulation •Acid Rain •Ozone Layer Depletion •Human Impact •Nuclear Power •Fossil Fuels •Air •Water •Water Quality •Biomagnification •Pesticides • Acid Rain •Ozone Issues • Land •Acid •Greenhouse Gas •Chlorofluorocarbons •Biomagnification •Eutrophication • Plants and Global Warming •Shrinking Sea Ice •Two Minor Science Stories - Greenhouse Effect - Biological Magnification of DDT
30.4 Solving environmental problems requires individual involvement.
• All of these challenges to our future can and must be addressed. Today, environmental scientists and concerned citizens are actively searching for constructive solutions to these problems.		7.  What sort of action might you take that would make a significant contribution to solving the world's environmental problems?		• History of Life • Do-It-Yourself Environmentalism

•  Scientists on Science •  How Scientists Think •  Student Papers

•  Bioethics Case Studies •  General Biology Weblinks

• Essential Study Partner

• Multiple Choice Quiz