1. Greenhouse Effect (E 3 ) Pages 447-449 1) Definitions 2) Description 3) Greenhouse Gases 4) Greenhouse Gases Effect on Atmosphere

2. Definitions  Greenhouse Effect A heating effect occurring in the atmosphere because of the presence of greenhouse gases that absorb infrared radiation  Greenhouse Gases Molecules that contribute to the greenhouse effect and global warming by absorbing infrared energy emitted or reflected from the surface of the earth

3. Objective One: Describe the Greenhouse Effect  Earth’s Temperature Short wavelength sunlight  Some energy absorbed by surface  Remaining reflected off the surface=longer wave radiation Longer Wave Radiation (infrared)  Absorbed by greenhouse gases and reradiated  Greenhouse Gases 1 way filters:  Shortwave (visible & UV) can pass through, long wave (infrared) cannot Maintain Earth’s temperature (60)

4. “Enhanced” Greenhouse Effect  Global Warming The increase in the temperature of the Earth’s atmosphere since the Industrial Revolution. Believed to be a consequence of rising levels of greenhouse gases (CO 2 ) which are enhancing the greenhouse effect

5. Objective Two: List the main greenhouse gases and their sources, and discuss their relative effects GasH2OH2OCO 2 CH 4 N2ON2OO3O3 CFCs % Volume 0 − 43.7 × 10 -2 1.7 × 10 -4 3 × 10 -5 4 × 10 - 6 2 × 10 -8 Relative Effectiveness 0.11301602,00010,000 − 25,000 Contribution to Global Warming 50 − 60%15 − 18%6%12%8 − 14% Atmospheric Life (years) 200 − 5007 − 10120 − 15080

6. Main Sources  Water Vapor: H 2 O Evaporation from bodies of water; product of hydrocarbon combustion  Carbon Dioxide: CO 2 Combustion of fossil fuels, forest fires, decay of plants and animals  Methane: CH 4 Anaerobic decomposition of organic matter; from ruminant animals (cows & sheep by bacterial breakdown of cellulose), rice paddies, oil and gas fields

7. Main Sources (continued)  Dinitrogen Monoxide: N 2 O Bacterial action, use of nitrogen-based fertilizers  Ozone: O 3 Photochemical smog  Chlorofluorocarbons: CFCs In spray can propellants, old refrigerators and air conditioners, as solvents, production of plastic foams (no natural source)

8. Objective Three: Discuss the influence of increasing amounts of greenhouse gases on the atmosphere  3 main effects 1) Increase in temperature 2) 1% increase in precipitation 3) 15-20 cm worldwide rise in sea levels o Melting of glaciers and ice caps o Physical expansion of H 2 O because of warmer temperatures o More changes as concentration of greenhouse gases increase

9. Additional Effects of Global Warming  Health Life cycles of pathogens and insects (like mosquitoes) are affected by climate Greater chance of malaria, etc.  Agriculture Effect on crop yields and geographic distribution of crops  Forests Insects and diseases may increase Increase in summer droughts would produce more forest fires Higher temps and more rain should help forests grow more rapidly

10. Global Warming Effects (continued)  Water Resources Decreased water quality due to flooding  Floods more likely due to more intense rainfall Droughts more severe due to increased evaporation and drier soil  Coastal Areas Raise the level of seas eroding beaches, inundation low lands, increasing coastal flooding  Species and Natural Areas Loss of cold water fish habitat Shift in ecological areas Loss of habitats and species Desertification