1. Atmospheric Chemistry Atmospheric Chemistry

2. Objectives Know the components of the atmosphere.
Discuss the different forms of electromagnetic radiation emitted by the sun.
Understand how solar radiation interacts with the atmosphere.

3. Components of the Atmosphere
1% Ar
varies H2O
<1% CO2
<1% CH4
<1% ozone, O3 (block UV)
“greenhouse gases”
trap heat

4. Solar Radiation Sunlight is mostly: ultraviolet, UV visible light, VL
infrared, IR UV

5. Absorption of UV and IR
Ozone absorbs UV
CO2 and H2O
absorb IR

6. Energy Budget IR heats air; emits to space as IR
IR VL UV
IR heats air; emits to space as IR
VL reflects back to space; or heats surface and IR emits to space
ozone converts UV to IR, emits to space
energy in = energy out
global temperature stays fairly constant

7. Objectives Understand how CO2 affects global temperature.
Be familiar with opinion polls regarding global warming.
Understand how ice core samples show a relationship between CO2 and temperature.
Be familiar with modern data regarding changing atmospheric conditions.
Know which countries/regions produce the greatest quantities of CO2.

8. Global Warming fossil fuels: coal, oil, natural gas
fossil fuel + O2 → H2O + CO2
greenhouse effect: gases such as CO2 or CH4 act like a blanket, maintaining a higher average temperature
global warming: more greenhouse gases result in a warming effect (like adding more blankets)
global dimming: more clouds (from heating and smog) result in a cooling effect
warming > cooling
97% of climatologists say humans play a role in global warming. U of Illinois-Chicago Survey

9. Scientist Survey

10. Public Opinion

11. Ice Core Data source: IPCC
Trapped air in ice cores reveal CO2 levels.
Low levels of oxygen-18 in ice = lower temperatures.
CO2 and temperature are closely related.

12. Ice core samples taken from two locations
650 km apart show data is credible

13. Increasing CO2 Levels CO2 levels up from 315 to 390 ppm (up 24%)
1 kg of gasoline
makes 3 kg of CO2
CO2 levels up from 315 to 390 ppm (up 24%)
US Dept of Energy

14. Temperature Change avg. global temperatures up 0.8o C
Goddard Institute for
Space Studies (NASA)
avg. global temperatures up 0.8o C
most warming in polar regions

15. Who makes greenhouse gases?
The US and China produce about 1/2
of all human-caused CO2 emissions.

16. Predicting Future Global Climate Change

17. Objectives
Understand that computers can be used to predict future climates.
Be familiar with potential future climatic conditions predicted by computer models.
Be familiar with environmental changes that are currently occurring in polar regions.

18. Computer Models
Computer models for climate changes are pretty accurate.
1950
2000

19. CO2 Scenarios
Various CO2 possibilities are used to make predictions about the future. (IPCC report)

20. Temperature Changes
Temperatures
rise 2oC – 4oC
(source: IPCC)

21. Sea-Level Changes
Sea-levels rise
30 cm – 50 cm
(source IPCC)

22. Melting Ice Sheets
Trapped air in ice cores
Greenland’s ice is melting four times faster than it was in 2002; about 65 mi3/yr (Science, 2009).
Sea levels now expected to rise 32 cm by 2050 (Geophysical Research Letters)
video1
video2
NASA, 2007

23. Arctic Perennial Ice
The summer arctic ice cap is now about ½ as large as historical average.
Less ice results in less reflection, more absorption, and increased warming.
NASA, 2007

24. Objectives Understand the impact of melting ice sheets.
Be familiar with the thermohaline cycle and its influence on climate.

25. Long-term Sea Level Rise
Melting the entire West Antarctic Ice Sheet or the Greenland Ice Sheet would each raise sea-levels by about 20 feet (for each).
But this will take 1000s of years at current rates.

26. Thermo-Haline Cycle
Ocean currents transfer heat from the equator to the poles.
Melting ice caps may stop this cycle and cool off climate in Europe.
Ice age patterns may be related to this process.

27. Global Dimming Air pollution particles produce more cloud cover.
More clouds trap heat → warming effect
But less sunlight hits surface → cooling effect
Air pollution has
reduced the amount
of global warming!