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) and IPCC AR5 Ch. 2 (pp. 174-180)

2. © AMS2 Driving Question  How do human activities affect global climate and how significant are those influences compared to natural causes of climate change?

3. © AMS3 Human Activity and Climate Change  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

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

5. © AMS5 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) “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 Fossil fuel combustion accounts for 75% of the increase in atmospheric carbon dioxide deforestation is likely responsible for the balancedeforestation 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 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. 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. Why are Greenhouse Gases Important?

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)

14. CO 2 at Mauna Loa and South Pole (Red) and NOAA (Blue) IPCC AR5

15. CH 4 at UCI (Green), AGAGE (Red) and NOAA (Blue) IPCC AR5

16. N 2 O at AGAGE (Red) and NOAA (Blue) IPCC AR5

17. 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

18. +3.0 w m -2 IPCC AR5

19. +3.0 w m -2

20. 1000 Years of CO 2 and Temperatures Figure 10.29

21. Does correlation equate to causation? Why or why not? Write for 5 minutes and submit with your name on the paper! CO 2 and Temperature

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