Lecture 34 The Human Impact on Earths 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. • It remains to be seen if we can use our resources for sustainable development.

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.

1. 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. )

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

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

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%

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

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.

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

1. Civilization as a Global Geosystem: U. S. Energy Consumption

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

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

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

2. Fossil-Fuel Resources: Remaining Nonrenewable Fossil Fuel

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

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.

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

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

2. Fossil-Fuel Resources: Estimated World Oil Reserves

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

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

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

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

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

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

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

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

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

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

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

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