Human Impacts on the Environment

1. Human Impacts on the Environment

2. People

3. Population • All the members of a species living in a given area • Human population has exploded over the last couple centuries • due to improved health care, clean water, etc

4. Carrying Capacity • The largest number of individuals of a given species that Earth’s resources can support and maintain for a long period of time • populations that exceed carrying capacity will begin to die off due to lack of resources (food, water, space)

5. Impacts on Land

6. Humans Using Land - Forest Resources • Trees are cut down to make wood and paper products, and to clear land for development • Deforestation • removal of large area of forests for human purposes

7. Habitat destruction • Soil erosion • plant roots hold soil in place; without plants the soil erodes away • Air quality • less oxygen and more carbon dioxide in the air Effects of Deforestation

8. Humans Using Land - Agriculture • Large areas of land cleared for farming and cattle grazing • Effects of Agriculture • Fertilizers • add excess nitrogen to the soil • pollute groundwater • Desertification • the development of desert-like conditions due to human activities • can occur due to soil erosion and/or over farming

9. Humans Using Land - Mining • Removal of rocks and minerals from the ground • Effects of Mining • disturbing habitats • changes the landscape • water pollution from runoff

10. Urbanization • the movement of human populations into cities • Urban Sprawl • the development of land for houses and other buildings near a city • Effects of Urbanization • habitat destruction • reduced water quality due to increased runoff Construction and Development

11. Preservation • Governments can protect land by setting aside wild areas • There are laws about how the resources there can be removed • Forests are complex but they can be managed to preserve the ecosystem • Select-cutting- only certain trees in one area are cut down rather than lots of trees or all the trees • Reforestation- replanting trees that have been cut or burned down • Reclamation- restoring land that has been disturbed by mining Positive actions

12. Green Spaces • Cities use green spaces to create natural environments in urban settings • They provide places for recreation for people and habitat for wildlife • They reduce runoff and improve air quality as plants take up extra carbon dioxide Positive actions

13. Reusing, Reducing, & Recycling • Composting • Reduces the amount of trash that ends up in landfills. • It involves mixing food scraps, leaves, and grass clippings and adding the decayed product to soil. Positive actions

14. Impacts on Water

15. Water as a Resource • most water is used in power plants to generate electricity

16. Sources of Water Pollution Point-Source Pollution Nonpoint-Source Pollution pollution from several widespread sources that cannot be traced to a single location ex. agricultural and urban runoff Most of the United States’ water pollution is nonpoint-source • pollution from a single source that can be identified • ex. oil spills, mining runoff

17. Positive Actions • National Initiatives: • Clean Water Act • regulates sources of water pollution • Safe Drinking Water Act • protects supplies of drinking throughout the country • How You Can Help: • Reduce use of harmful chemicals • Dispose of waste safely • Conserve water

18. Impacts on the Atmosphere

19. Types of Air Pollution - Smog • Smog • nitrogen and carbon compounds are released from burning fossil fuels • these compounds react with sunlight to make ozone and other chemicals

20. Types of Air Pollution – Acid Rain • Acid Rain • rain or snow that has a lower pH than that of normal rainwater • makes soil more acidic, making it difficult for plants to survive

21. Other Types of Air Pollution • Particulate Matter • mix of both solid and liquid particles in the air • ex. smoke, dust • CFCs • destroy ozone molecules • Carbon Monoxide • released from cars and forest fires

22. Global Warming • burning fossil fuels releases excess amounts of carbon dioxide into the air • this can lead to an increase in Earth’s average surface temperature

23. Effects of Global Warming • Melting of ice caps and a rise in sea level • More storms due to higher ocean temperatures • Extinction of cold-weather species

24. The Greenhouse Effect • The natural process that occurs when gases in the atmosphere absorb and reradiate thermal energy from the Sun • Increased carbon dioxide traps more heat in the atmosphere

25. Health Disorders • Air pollution can cause respiratory problems, including asthma attacks, in which the passageways in the lungs become narrower and breathing becomes difficult. • The government measures and reports air quality using the Air Quality Index, which is a scale that ranks the level of ozone and other pollutants.

26. Montreal Protocol • Countries around the world have agreed to phase out CFC’s and to lower emissions of green house gases to help reduce problems due to Air pollution • Clean Air Act • Since it was passed in 1970, we have seen a 50% reduction in pollutants that cause acid rain and a 90% reduction in air pollution from factories. Positive actions

27. Using Renewable Energy • Renewable resources such as solar power, wind power, and geothermal energy helps reduce air pollution • Using Less Energy • Helps reduce pollution and improve the quality of all our important resources: water, air, soil Positive actions