Lecture Outline - Chapter 24

24.1 Exponential Population Growth (p. 490, Fig. 24.2)
	1.	The human population is growing exponentially. Since the world's population is already very large, increases occur faster.
	2.	The Growth Rate Depends on Births Versus Deaths (p. 491)
		Growth rate is determined by the birth rate and the death rate of a population, usually per 1,000 individuals.
	3.	Doubling Time Depends on Growth Rate (p. 491)
		a.	The doubling time (d) is calculated by dividing the demographic constant by the growth rate.
		b.	The present human population has a doubling time of 44 years.
	4.	Carrying Capacity Limits Population Size (p. 491, Fig. 24.3)
		a.	The biotic potential of a population is the maximum growth rate under ideal conditions.
		b.	Biotic potential does not last long because of environmental resistance.
		c.	Carrying capacity is the maximum population the habitat can support indefinitely. The effects of environmental resistance become more pronounced as the population approaches the carrying capacity.
24.2 Human Population Growth (p. 492)
	1.	Human populations have undergone several periods of rapid growth: during the emergence of toolmaking, during the rise of farming, and since the Industrial Revolution.
	2.	More-Developed Versus Less-Developed Countries (p. 492, Fig. 24.4)
		a.	The more-developed countries (MDCs) doubled their populations between 1850 and 1950, due to a decline in the death rate and improved living conditions. A demographic transition followed.
		b.	The less-developed countries (LDCs) have a higher growth rate than the MDCs. That rate peaked in the early 1960s. Since then, a demographic transition has begun. High growth rates continue in Africa, Asia, and Latin America.
		c.	Ways to decrease the growth rate in these areas include establishing family planning programs, using social progress to lessen the desire for large families, and delaying the onset of childbearing.
		d.	Comparing Age Structure (p. 493, Fig. 24.5)
			Human populations can be broken down into three age groups: dependency, reproductive, and postreproductive. Most LDCs have a large dependency base, indicating population growth will continue for some time. Many MDCs have a stabilized age structure.
24.3 Human Population and Pollution (p. 494)
	1.	Pollutants are substances added to the environment that have undesirable or toxic effects.
	2.	Air Pollution (p. 494, Fig. 24.6)
		a.	Energy conservation measures could greatly curtail the four major problems in air pollution.
		b.	Global Warming from Greenhouse Gases (p. 494, Fig. 24.7)
			i.	Certain gases in the atmosphere absorb heat and reradiate it back to earth, a phenomenon known as the greenhouse effect. 
			ii.	Carbon dioxide emissions from burning fossil fuels and deforestation are responsible for 50% of the predicted rise in global temperature.
		c.	Destroying the World's Ozone Shield (p. 496, Fig. 24.8)
			i.	The stratosphere contains a layer of ozone, which protects earth from the destructive ultraviolet rays of the sun.
			ii.	Destruction of the ozone shield will result in increased incidence of skin cancer and cataracts, and will have adverse effects on the immune system.
			iii.	Destruction of the ozone layer is due to chlorofluorocarbons (CFCs) from coolants used in refrigeration and from foaming agents. The United States banned the use of CFCs in propellants, and most countries of the world will stop using them by the year 2000.
		d.	Acid Deposition Destroys Ecosystems (p. 496, Fig. 24.9)
			i.	The burning of coal and oil in power plants releases sulfur dioxide into the air. Automobile exhaust releases nitrogen oxides into the air. Both of these compounds combine with water vapor and produce sulfuric or nitric acid, which returns to earth with precipitation or dust.
			ii.	Acid deposition has led to the destruction of lakes and forests in North America and Europe. 
		e.	Photochemical Smog Affects Health (p. 497, Fig. 24.10) 
			i.	Nitrogen oxides and hydrocarbons from automobile exhaust react together in the presence of sunlight to produce ozone and PAN (peroxyacetyl nitrate), the components of photochemical smog. Ozone and PAN are oxidants and cause respiratory distress and nervous system problems. Ozone is especially damaging to plants.
			ii.	Carbon monoxide from burning fossil fuels combines more readily with hemoglobin than does oxygen.
			iii.	In mountainous areas, a thermal inversion sometimes occurs, where cold air near the ground cannot escape from underneath the overlying warm layer, and pollutants build up.
	3.	Water Use and Pollution (p. 498, Fig. 24.11)
		a.	Fresh water has a myriad of uses, including drinking water, irrigation, industrial use, and energy production. Underground aquifers are also used for these purposes, but aquifer water is currently withdrawn faster than it is naturally replaced. 
		b.	Surface Water Pollution (p. 498)
			i.	Sewage treatment plants use bacteria to break down sewage to inorganic nutrients that, when added to surface waters, increase the rate of primary production, a process called cultural eutrophication. Massive fish kills result.
			ii.	Industrial wastes contribute to water pollution. They accumulate in sediments and cause problems when disturbed.
		c.	Groundwater Pollution (p. 498)
			i.	Especially in agricultural areas, groundwaters are contaminated with nitrates, the result of overfertilization of crops.
			ii.	Industry also pollutes groundwater during waste disposal.
		d.	Pollution of the Oceans (p. 499, Fig. 24.12)
			i.	Coastal regions are the final receptors for pollutants deposited in rivers plus any generated along the coastline itself. Nonbiodegradable trash washes onshore, choking marine wildlife.
			ii.	Offshore oil drilling and mining contribute greatly to ocean pollution, especially during oil spills.
		e.	Losing Marine Biodiversity (p. 499)
			Pollution of oceans and exploitation of their resources have led to the severe decline of many commercial fisheries. Pollution kills off coral communities, denuding coral reefs of their diverse biota.
	4.	Land Pollution (p. 500)
		a.	Waste Disposal and Dangerous Trash (p. 500, Fig. 24.13)
			i.	In the United States, people discard millions of tons of trash each year. Open dumping has been a common practice, and landfills are running out of room.
			ii.	Hazardous wastes are a component of land pollution, and many of them are very dangerous to health. These wastes are subject to biological magnification.
		b.	Soil Erodes and Deserts Grow (p. 500, Fig. 24.14)
			i.	Erosion of topsoil in agricultural areas causes the loss of billions of tons of soil annually.
			ii.	Desertification, or the expanding of deserts, is caused by overgrazing and overfarming of marginal lands, especially in Africa.
		c.	Losing Terrestrial Biodiversity (p. 501, Fig. 24.15)
			Wars cause land spoilage and habitat destruction, and global deforestation of coniferous and tropical forests is leading to an alarming role of biodiversity loss. Animals living in forests will be displaced. Probably 1 million species of plants and animals are now faced with extinction. Many of these organisms could directly or indirectly benefit humans.
			ECOLOGY FOCUS: Ten Ways to Reduce Your Impact on the Environment (p. 503)  Ways to reduce your impact on the environment include avoiding products with excessive packaging, using compact fluorescent light bulbs, buying unbleached or chlorine-free paper products, using rechargeable alkaline batteries, and washing clothes in cold water.
24.4 A Sustainable World (p. 504, Fig. 24.16)
	1.	To sustain our populations, development must meet the needs of people while at the same time protecting the environment.
	2.	Selective tree cutting while preserving the forest is one example.