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Greenhouse Gases

Greenhouse Gases. Greenhouse Gases. Carbon dioxide (CO 2 ) Methane (CH 4 ) Nitrous Oxide (N 2 O) Chlorofluorocarbons (CFCs) Water vapour Ozone (O 3 ). These gases produced end up in the atmosphere rather than absorbed by the ocean and forests. Sources of CO 2.

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Greenhouse Gases

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  1. Greenhouse Gases

  2. Greenhouse Gases Carbon dioxide (CO2) Methane (CH4) Nitrous Oxide (N2O) Chlorofluorocarbons (CFCs) Water vapour Ozone (O3)

  3. These gases produced end up in the atmosphererather than absorbed by the ocean and forests

  4. Sources of CO2 Accounts for 25% of the greenhouse effect!

  5. Effects of Deforestation • About 10% of CO2 emissions are due to deforestation • Effects: • Stops absorption of CO2 • Forest waste decomposes to produce CO2 and CH4

  6. Forests: Sources or Sinks? Healthy forests: carbon sinks Unhealthy forests: carbon sources

  7. Sources of CH4 • Agricultural activities: rice farming, cattle ranching • Decay of organic material in landfills and sewage treatment plants • Coal mining and natural gas extraction • Deforestation (from burning)

  8. Sources of N2O Livestock feed & waste management Nitrogen fertilizers Industrial processes

  9. Sources of CFCs No natural source Refrigeration agents in fridges and A/C International treaties (i.e. Montreal Protocol) on Substances that Deplete the Ozone Layer helped to  the amount of CFCs that are released by industrial processes

  10. Sources of O3 • Ground-level O3 (lower troposphere): solar UV radiation + emissions to produce toxic chemicals + O3 • Major component of urban pollution = SMOG • Harmful to life

  11. Sources of O3 • Upper-level O3 (stratosphere): absorbs UV rays from the sun • Protect us from skin cancer, cataracts… • Damage plants; reduce productivity

  12. Ozone depletion Blue and purple indicates the lowest concentration of ozone • Ozone hole: large opening in the ozone layer • Most evident over the polar regions • Largest hole in Antarctica (2006)

  13. UV index: a Canadian invention A scale that tells us how much time in the Sun would cause sunburn on a specific day

  14. Water vapour The quantity of atmospheric water vapour depends on the temperature of the atmosphere Recall: water traps heat energy well

  15. The Greenhouse Effect Anthropogenic Greenhouse Gases and Global Temperatures

  16. Greenhouse effect

  17. Greenhouse effect Greenhouse gases & clouds absorb infrared radiation emitted from the Earth’s surface and radiate it back in all directions, heating the atmosphere and Earth’s surface

  18. Greenhouse effect Even though CO2 is more abundant, CH4 and N2O are more powerful molecules in contributing to the greenhouse effect They absorb more thermal energy

  19. CO2 and Global Temperatures The Oceans and Forests are carbon sinks

  20. The Future • The concentration of CO2 in the atmosphere is higher today than it has been for hundreds of thousands of years • If we continue to produce greenhouse gases at this rate, we will likely see temperatures increase by 2-6˚C by the end of the century • Impacts devastating: extreme weather, species extinction, etc. p. 342 #1, 2 5

  21. Studying Past Climates Using Tree Rings to predict past climate Trees create one growth ring per year. Tree rings are thickest in years with good growing conditions p. 361 #4b P. 378 #1, 4a, 5a P. 389 #1,2, 4, 5

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