Unit 6 Part III: Human Environment Interaction

1. Unit 6 Part III: Human Environment Interaction Stress on the Earth’s Landscape

2. I. Alteration of Ecosystems • From the beginning…fires, hunted, exterminated • Ecosystem-ecological units consisting of self-regulating associations of living and nonliving natural elements

3. II. Environmental Stress • A. Obvious Actions-cutting of forests, emission of pollutants • B. Less Obvious Actions-burying of toxic wastes, dumping garbage, use of pesticides • C. Concerns-future of water supplies, state of the atmosphere, climate change, desertification, deforestation, soil degradation, disposal of industrial wastes

4. Water • renewable resource, availability is not evenly distributed, most along equator a. distribution is sustained through hydrologic cycle b. aquifers-water-holding rocks/wells that distribute H20 Sign. 50x as much in aquifers as precipitation c. water shortages –Africa, S. California, Spain

5. California Water Issues • 80% water used for irrigation • Supply insufficient for population • Colorado River flow diminishing

6. The Aral Sea • Once the 4th largest lake on earth. • Water diverted for Soviet Union cotton irrigation upstream on the Amu Darya and Syr Darya Rivers. • Watch the following video clip… http://www.youtube.com/watch?v=NC5UIEx83fo

7. The Aral Sea

8. The Aral Sea

10. Politics and Water in the Middle East Israel has one of the lowest natural renewable water resources in the world • ½ of water supply comes from areas outside of Israeli state • Jordan River key source of water supply for Israel, along with aquifers beneath the West Bank • Desalinization is one of the ways in which Israel attempts to meet water demand throughout the state • Note: most water comes non-Israeli states

11. 80% of China’s rivers are unfit for human contact. Aquatic life in these rivers is in decline.

12. 40% of U.S. rivers, lakes, and streams are not fit for swimming, fishing, or drinking.

13. Global Atmospheric Issues The Ozone Hole Global Warming Acid Rain

14. The Greenhouse Effect • A normal climatic warming effect caused by permitting incoming solar radiation but inhibiting outgoing terrestrial radiation. • Three gases are the primary cause: • Carbon Dioxide (CO2) • Methane (CH4) • Water Vapor (H2O) • The effect is possible because outgoing earth radiation is of much longer wavelengths than incoming insulation.

15. Global Warming

16. The Global Warming Hypothesis Human-induced rise in CO2 levels is causing unnatural warming of atmosphere. • Likely effects: • Increased storminess • Rising sea level (.2-1 meter in 100 years – IPCC, 2001) • Loss of arable land (some areas hotter, others cooler) • Extinction of thousands of species • Loss of nearly all coral reef • Millions of climate refugees • Loss of Arctic sea ice during summer

17. Acid Rain Burning fossil fuels-emission of sulfur dioxide and nitrogen oxide Leads to acidification of lakes and streams, stunted growth of forests, loss of crops

18. The Land • I. Deforestation-44% of tropical rainforests had been cut down in the 1980s; predictions that all rainforests will be gone in less than 90 years; second-growth forests uninhabitable by most animal species • II. Soil Erosion-pressures on land to produce more; 37,000 acres lost each year to livestock, wind erosion, dry climate • III. Waste Disposal-U.S. largest producer of solid waste (3.7 lbs./person/day); open vs. sanitary landfills; suitable land for landfills decreasing; toxic (chemicals) vs. radioactive (low vs. high radiation)

19. Loss of Biodiversity U.N.’s Environmental Program’s Global Diversity Assessment indicates 8% of plants, 5% of fish, 11% of birds, and 18% of the world’s mammal species are currently threatened. *Species on islands are particularly susceptible to extinction. Why?