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Greenhouse Gases

Greenhouse Gases. Current Weather Anthropogenic Influences on Climate Why are Greenhouse Gases Important? Carbon Dioxide, Methane, and Nitrous Oxide Radiative Forcing of Greenhouse Gases For Next Class: Read Ch. 12 (pp. 374). Driving Question.

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Greenhouse Gases

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  1. Greenhouse Gases • Current Weather • Anthropogenic Influences on Climate • Why are Greenhouse Gases Important? • Carbon Dioxide, Methane, and Nitrous Oxide • Radiative Forcing of Greenhouse Gases For Next Class: Read Ch. 12 (pp. 374)

  2. Driving Question • How do human activities affect global climate and how significant are those influences compared to natural causes of climate change?

  3. In 2013, the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming since the mid-20th century very likely (estimated probability greater than 90%) was caused mostly (>50%) by human activities Human Activity and Climate Change

  4. Anthropogenic Forcings on Climate • Greenhouse gases • Aerosols • Land use/land cover change

  5. Human Activity and Climate Change • Trends in Greenhouse Gases • “Most of the increase in globally-averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG (greenhouse gas) concentrations.” (IPCC 2007) • Fossil fuel combustion accounts for 75% of the increase in atmospheric carbon dioxide • deforestation is likely responsible for the balance • Rising levels of other infrared-absorbing gases associated with human activity (e.g., methane, nitrous oxide, halocarbons, and ozone) enhance the greenhouse effect

  6. Earth–Atmosphere Radiation Balance Figure 4.12

  7. Atmospheric Absorption in the EM Spectrum

  8. Why are Greenhouse Gases Important? • Absorb long-wave terrestrial radiation, heating the atmosphere, and radiating this energy back to the surface. • Critical for life on Earth. • Without greenhouse effect, surface temperatures would be extremely cold at night. • Too much of a good thing, however, is a concern.

  9. A rectangular piece of coal in a wagon is on display in the middle of Pacific Avenue In Tacoma before the arrival of President Harrison in May, 1891.

  10. Life Magazine (1962)

  11. CO2 at Mauna Loa and South Pole (Red) and NOAA (Blue) IPCC AR5

  12. CH4 at UCI (Green), AGAGE (Red) and NOAA (Blue) IPCC AR5

  13. N2O at AGAGE (Red) and NOAA (Blue) IPCC AR5

  14. Temperature Impact in 100 Years by Sector IPCC AR5

  15. What is Radiative Forcing? • “The change in net (down minus up) irradiance (solar plus longwave; in W m-2) at the tropopause” (IPCC AR5 Ch. 2) • Abbreviated RF • Positive RF implies warming • Negative RF implies cooling

  16. +3.0 w m-2 IPCC AR5

  17. +3.0 w m-2

  18. 1000Yearsof CO2and Temperatures Figure 10.29

  19. CO2 and Temperature • Does correlation equate to causation? Why or why not? • Write for 5 minutes and submit with your name on the paper!

  20. No denying that the anthropogenic greenhouse effect is playing a role: Question is how much?

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