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Lecture

SCIE 1P50 Lecture Notes - Fertilizer, Smog, Halocarbon


Department
Science
Course Code
SCIE 1P50
Professor
Caroline Starrs

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Class #26! ! Science & Society November. 7, 2011
Human Activity has Released Carbon from Sequestration in Long-term Reservoirs
- Human activities accelerate the fluxes of material from one reservoir to another in
biogeochemical cycles
- Burning fossil fuels transfers CO2 from lithospheric reservoirs into the
atmosphere
- Deforestation transfers CO2 from terrestrials into the atmosphere
Greenhouse Gases and Earth’s Climate
- Carbon Dioxide CO2
- Water Vapor H2O
- Ozone O3
- Methane CH4
- Nitrous Oxide N2O
Other Greenhouse Gases
- Methane CH4 from fossil fuel deposits, livestock, landfills, and crops such as rice
- Nitrous oxide N2O from feedlots, chemical manufacturing plants, auto emissions, and
synthetic nitrogen fertilizers
- Ozone O3 from photochemical smog
- Halocarbons (CFCs and HFCs)
- Water vapor = the most abundant greenhouse gas and contributes most to the
greenhouse effect
There are Many Feedback Cycles in the Climate System
- Positive Feedback Loop
- Adding carbon dioxide to the atmosphere tends to warm the atmosphere
causing global warming
- The warm atmosphere causes surface water to evaporate and become water
vapor
- Since water vapor is a greenhouse gas, the atmosphere tends to warm even
more as water vapor increases.
- Negative Feedback Loop
- Adding carbon dioxide to the atmosphere tends to warm the atmosphere,
causing global warming
- The warm atmosphere causes surface water to evaporate and become water
vapor
- Some water vapor condenses to form clouds. Clouds contribute to the
greenhouse effect by trapping heat in the atmosphere, but they also reflect the
solar energy back to space, helping to cool the planet.
-Aerosols = microscopic droplets and particles that have either a warming or cooling
effect
- Radiative forcing = the amount of change in energy that a given factor causes
-Positive forcing warms the surface; negative forcing cools it
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