1. Unit 3: Human Impact I. Why is human population growth an environmental problem? A.Causes of human population growth 1. Agricultural Revolution – people settle into communities and more people were needed for division of labor; more reliable food supply can support a larger population. 2. Industrial Revolution – In the early 20th century technological advancements led to improvements in medicine and sanitation allowing for an increased birth rate and decreased death rate. 3. Urbanization (development of cities) leads to economic and social development which influence human populations.

2. Unit 3: Human Impact I. Why is human population growth an environmental problem? B. Effects of human population 1. Overcrowding – may lead to tension and crime. 2. Increased pollution – air, water, and land ALL pollution problems relate back to overpopulation. 3. Decreased natural resources, especially nonrenewable resources (available only in limited amounts). Ex. fossil fuels, minerals, metals 4. Increased land use – leads to loss of habitat for other species.

3. Unit 3: Human Impact I. Why is human population growth an environmental problem? C. Solution 1. ZPG – zero population growth (birth rate = death rate). a. Limit number of births per family by offering tax incentives Ex. China b. Make birth control and family planning more available. c. Educate public and our political leaders. 2. Conservation – wise and careful use of resources a. Twenty percent of the world’s population uses more than fifty percent of the world’s resources. =

4. Unit 3: Human Impact b. People in developed countries (like the U.S.) can decrease resource use by the 3 R’s: i. Reduce – use less materials; for example, buying products that have less packaging ii. Reuse – use products more than once; for example, bring lunch in Tupperware instead of one-use containers iii. Recycle – return products to be re-processed; for example, old tires are used to make track surfaces c. Sustainability – ensuring the availability of resources and a stable environment for future generations. I. Why is human population growth an environmental problem?

5. Unit 3: Human Impact II.How do local problems affect global conditions? A.Global Warming 1.Cause: Excessive greenhouse gases (CO2 and CH4) in the atmosphere trap heat, leading to an abnormal increase in earth’s surface temperature a. CO2 comes from burning fossil fuels in power plants, factories, and cars. Map shows top 10 production countries b. CH4 comes from bacteria in landfills and cow farts 2.Effects: With just a small increase in temperature (2- 4 degrees Celsius), weather patterns will change worldwide. Polar ice caps may melt, flooding coastal cities and contaminating drinking water with saltwater.

6. Global Warming Animation Global Warming in short

7. Unit 3: Human Impact I.How do local problems affect global conditions? B. Ozone Depletion 1. Cause: CFCs, once used as refrigerants and in aerosol cans,escape to the upper atmosphere and destroy many ozone molecules. This leads to a “hole”, or thinning, of the ozone layer. The CFCs can last decades, even though now banned. 2. Effects: A thinner ozone layer allows harmful UV radiation to reach earth’s surface causing increased incidence of sunburn, skin cancer, cataracts (leading to blindness), and crop damage. 3. Note: Ozone is “good” up high; “bad” nearby. This means ozone in the upper atmosphere blocks harmful UV rays, but ozone in the lower atmosphere (near us) causes respiratory ailments and damage to plant life.

8. Unit 3: Human Impact I.How do local problems affect global conditions? C. Acid Precipitation 1.Cause: Harmful emissions from cars and factories (especially nitrous oxide and sulfur oxide) react with oxygen and water to make precipitation (rain, etc) more acidic (pH less than 5.6) 2. Effects: A lowered pH disrupts aquatic ecosystems, makes soil less fertile, harms plant life, and damages human property.

9. Unit 3: Human Impact 1. Cause: Sources of water pollution often begin on land, such as oil from cars, sediments from naked land, and fertilizers from lawns. Other sources include illegal chemical dumping, acid rain, overheated water from power plants, and raw sewage. 2. Effects: A lack of clean drinking water is a leading cause of disease (such as cholera, dysentery, typhoid). Water pollution also affects many ecosystems through habitat destruction. I.How do local problems affect global conditions? D. Water Quality

10. Unit 3: Human Impact III. How do humans negatively impact other species? A. Biodiversity – the number of different species of organisms that exist within an area and the genetic diversity within each species B. Causes of Biodiversity Loss: 1. Habitat Destruction a. Deforestation – forests are cut down for timber, agriculture, and development b. Fragmentation – natural territories are broken into areas too small to support native populations c. Draining/Filling Wetlands – for agriculture and development

11. Unit 3: Human Impact III. How do humans negatively impact other species? 2. Biomagnification of Pesticides Bioaccumulation – the build up of certain pesticides in the tissues of organisms (Ex. DDT in fish) Biomagnification – increasing concentration as pesticides move up the food chain (Ex. DDT in bald eagles)

12. Unit 3: Human Impact III. How do humans negatively impact other species? C.Effects of Biodiversity Loss: 1. Endangerment/Extinction of Species a. Endangered species are at risk of becoming extinct. Extinction refers to the loss of a particular species. b. The Endangered Species Act provides protection for species recognized and listed by the government. This Act does not, however, provide adequate protection of the habitat. 2. Loss of valuable medicinal or crop plants, and other species that may be potentially useful to humanity 3. Lack of genetic variety makes crops more susceptible to disease, pests, and environmental changes

13. I.What can you do to protect the environment? Unit 3: Human Impact A. Awareness – understand that each human has an impact on his/her environment, and that because our population is so large we have an ENORMOUS impact at the global level. “We cannot all do everything, but we can all do something.” B. Specific suggestions: 1. Reduce dependence on fossil fuels (Example – car pool, support “green power”) 2. Recycle whenever possible 3. Limit use of chemicals at home 4. Consumer choices – supporting businesses that are environmentally friendly, etc. 5. Political activism – Supporting candidates and legislation which are environmentally sound.

14. Unit 3: Human Impact V. What technology and techniques are used to study human impact on the environment? A.Global imaging – scientists use satellites to track changes global temperature and the ozone layer B.Ice core analysis – analyze ice formed long ago to determine the greenhouse gases present in the atmosphere at that time C. Census data – demographers construct histograms to use in predicting future population growth trends (field called “demography”) 2. Developed and Stable (Ex. United States) 3. Developed and Decreasing (Ex. Germany) (from www.cbc.yale.edu) 1.Developing and Growing (Ex. Sudan)