Main Questions:

• Is it proven?

• What are potential consequences?

• What can be done?

How Does This Relate to the Carbon Cycle?

• Sources of Increased Atmospheric CO2

  • Burning Fossil Fuels

  • Deforestation

• Carbon Balance: increased atmospheric CO2 less than expected based only on input

  • about 49% remains in atmosphere

  • about 29% uptake by oceans

  • carbon balance:  about 22% unaccounted for

Consequences of Increased Greenhouse Gases

• Human activity and natural processes lead to…

• Increased atmospheric greenhouse gases, which leads to…

• An increase in average global temperature, which causes…

• Changes in climate, which can lead to…

  • Droughts

  • Increased rainfall and storms

  • Rising sea levels

  • Loss of biodiversity

Climate Changes During the Past 900,000 Years

• Past cimate based on study of Antartic glaciers

• Cycles of Ice Ages lasting about 100,000 years

• Interglacial Periods lasting 10,000 to 12,500 years

Climate During the Past 160,000 Years

• End of last Ice Age about 10,000 yr BP

• Now in warm interglacial period

• Based on ice core data, analysis of trapped gas

• Correlation between CO2 and mean temperature

What is the Scientific Consensus?

• Mean global temperature rose about 0.6º C (1º F) in past 100 years

• Increase is real, not explained by natural variation in solar radiation

• Warming greater at poles than equator, greater at night, mostly troposphere

Future Scenarios

• General Circulation Models (GCMs) are used to predict future climates

• Projected warming of 1 to 3.5 º C between 1990 & 2100

• Likely scenario: doubling of CO2 (from 280 ppm to 560 ppm) before 2100 leading to warming of 2ºC

Role of the Oceans

• Storage of CO2 in deep water

• Warming could decrease ability of ocean to serve as “sink” for carbon

Ecological Implications

• Shift of habitat to higher latitudes

• Shift of habitat to higher elevations

• Potential large loss of biodiversity

Solutions to Global Warming

Prevention

• Cut fossil fuel use (especially coal) in half

• Improve energy efficiency

• Shift to renewable energy resources

• Reduce deforestation

• Use sustainable agriculture

• Slow population growth

Clean Energy Use

Cleanup

• Remove CO2 from vehicular and smokestack emissions

• Plant and tend to trees

Actions

• Waste less water

• Develop crops that need less water

• Move hazardous materials storage tanks away from coast

• Prohibit new construction or remodeling on low-lying coastal areas

• Stockpile 1-5 year supply of key foods

• Expand existing wildlife reserves toward the poles

• Connect wildlife reserves with corridors

International Agreements

Kyoto Agreement (1997)

• 38 developed countries must cut greenhouse gas emissions to 5.2% below 1990 levels between 2008-2012

• Developing countries exempted

• Allow emissions trading, in which countries can sell its excess reductions to others

  • Countries can also plant trees to meet goal

• Impact on U.S.: Economic Incentives/Regulatory Changes

  • Reduce energy use by 18%

  • Reduce electricity use by 30%

  • Cut SO2 emissions by 50%

  • Cut NO2 emissions by 25%

  • Cut CO2 emissions by 14% below 1990 levels

    • Twice the amount specified in the Kyoto Treaty