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Lecture 34 The Human Impact on Earth’s Environment

Lecture 34 The Human Impact on Earth’s Environment. About Human Impact Human population is immense, and resources are being consumed at an astounding rate. Balancing resource usage versus environmental protection is challenging.

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Lecture 34 The Human Impact on Earth’s Environment

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  1. Lecture 34 The Human Impact on Earth’s Environment

  2. About Human Impact • Human population is immense, and resources are being consumed at an astounding rate. • Balancing resource usage versus environmental protection is challenging. • It remains to be seen if we can use our resources for sustainable development.

  3. 1. Civilization as a Global Geosystem • Civilization exists at the thin interface among the climate, plate tectonic, and geodynamic systems. • Human civilization has profoundly altered the planet, especially in the last 200 years.

  4. Civilization as a Global Geosystem: • Human Population Growth • 10,000 years ago – 100 million people • 5,000 years ago – 200 million people • 700 years ago – 400 million people • By 1800 AD – 1 billion people • By 1974 – 4 billion people • By 2012 – 7 billion people • (World’s population doubles now in 47 years.)

  5. Civilization as a Global Geosystem: • Human Population Growth Scenario A: continued growth as now; B: late 21st-century level-off; C: decline after 2070

  6. 1. Civilization as a Global Geosystem • Humans now alter the global environment on a scale that is staggering compared to natural processes.

  7. 1. Civilization as a Global Geosystem ● Example of human changes ●dams and reservoirs now trap 30% of all river sediments ● humans move more soil and rock than all natural processes ● one third of forests cleared ●coolants have damaged the critical ozone layer ● carbon dioxide levels up by ~50%

  8. 1. Civilization as a Global Geosystem ● Natural energy resources ● Renewable energy resources ● biomass (wood burning) ●Nonrenewable energy resources ●fossil fuels (oil, gas, coal)

  9. 1. Civilization as a Global Geosystem ● Before 1850, most U.S. energy was from wood burning. ● After 1850: the rise of the U.S. fossil-fuel economy.

  10. 1. Civilization as a Global Geosystem * * Note – a quad is = to 1015Btus.

  11. Civilization as a Global Geosystem: • U.S. Energy Consumption

  12. Civilization as a Global Geosystem: • Projected Energy Consumption * * Note – OECD includes North America, western Europe, and Australia.

  13. 1. Civilization as a Global Geosystem ● Global carbon flux from energy production ● Huge increase from natural rates of carbon transfer ●Carbon economy ● Carbon dioxide is a greenhouse gas

  14. 2. Fossil-Fuel Resources ● Fossil-fuel resources and reserves ● Resources – have been discovered ● Reserves – remain in Earth

  15. 2. Fossil-Fuel Resources: Remaining Nonrenewable Fossil Fuel

  16. 2. Fossil-Fuel Resources ● How oil and gas forms ● Formed in source beds ● May move to reservoirs ● Raw petroleum: crude oil ● Natural gas: methane

  17. 2. Fossil-Fuel Resources ● How oil and gas forms ● Crude oil forms under limited conditions called the “oil window.” ● Crude oil resides in porous rock called an oil reservoir (oil trap). ● Similar conditions apply to gas.

  18. 2. Fossil-Fuel Resources: Traps for Oil and Gas

  19. 2. Fossil-Fuel Resources ● Distribution of oil resources ● Middle East ● U.S. Gulf Coast and Caribbean ● Other areas

  20. 2. Fossil-Fuel Resources: Estimated World Oil Reserves

  21. 2. Fossil-Fuel Resources ● Oil production and consumption ● In 2012, 35 billion barrels/yr ● U.S. consumes ~2 times what it produces ● U.S. trade deficit is heavily due to oil importation

  22. 2. Fossil-Fuel Resources ● Oil production and consumption ● Hubbert’s peak shows the time of maximum production ● U.S. peak in 1970 ● Departure from trend started in 2008

  23. 2. Fossil-Fuel Resources: U.S. Oil Production and Hubbert’s Peak

  24. 2. Fossil-Fuel Resources ● Oil and the environment ● oil spills during production ● oil spills during transportation ● contribution of carbon dioxide to the atmosphere

  25. 2. Fossil-Fuel Resources Oil spill during production: The Deepwater Horizon disaster (2010)

  26. 2. Fossil-Fuel Resources ● Natural gas production ● new technology – “fracking” ● gas from shales is the new frontier for exploration

  27. 2. Fossil-Fuel Resources Fracking: Producing gas from shale formations

  28. 2. Fossil-Fuel Resources Fracking: How shale gas production is changing the outlook of gas production in the U.S.

  29. 2. Fossil-Fuel Resources ● Natural gas and the environment ● Natural gas burns more cleanly than coal. ● Natural gas has higher carbon intensity than coal. ● Methane is a greenhouse gas, and burning gas emits CO2.

  30. 2. Fossil-Fuel Resources ● Coal and the environment ● mining pollution problems ● burning and acid rain problem ● contribution of carbon dioxide to the atmosphere

  31. 2. Fossil-Fuel Resources: Coal Fields of the U.S.

  32. 2. Fossil-Fuel Resources: Typical Coal Strip Mine West Virginia

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