2. Wind scale

4. Global warming - increased surface temperature due to natural and man-made causes. But……what’s the problem?
Questions:
1) What is the problem?: Increased atmospheric temperature.
2) What are the effects?: The effects are numerous. Rising sea level, more frequent and larger floods, shifting climate regions, biology.
3) Natural or man-made?: Both.
4) Should something be done? If so, what? Why? At what cost?

5. Methods:
1) Examine the processes and cycles involved.
2) Records of past climates and climate changes.
3) Measuring past and present day human activities: industrialization.
Conclusions:
You decide.

6. Factors that affect global climate:
Fluctuations in solar energy - 11-year sunspot cycle
Earth Orbital variations - distance from sun, angle of tilt
10, ,000 year cycles
Albedo - reflectivity of earth and atmosphere
clouds, ice, water, land, and plants
Factors that affect local climate:
Heat islands caused by cement and asphalt in cities.
Smog

7. Heat island

8. The Greenhouse Effect: gases in the troposphere absorb and re-radiate infrared radiation (heat). This warms the troposphere and makes the earth habitable.
Greenhouse gases:
CO2 Carbon Dioxide
H2O Water vapor
CH4 Methane
N2O Nitrous Oxide
O3 Ozone

9. The Greenhouse Effect - it’s natural!

10. The problem is: Enhanced Greenhouse Effect.
Causes:
Increased concentration of greenhouse gases. i.e. CO2
Decreased concentrations of ozone in the stratosphere.
First: What are the paths of carbon on the earth?

11. Carbon Cycle - without humans
Short time scale
Long time scale
Medium time scale

12. Long term cycling of Carbon due to volcanism and metamorphism
From Our Changing Planet, Mackenzie, 1997

14. Human input: ~1.0%/year
At this rate, CO2 would double in 70 years!

15. Mauna Loa Observations
Current CO2 concentration: ~360 ppm
Anthropogenic CO2 ?
Past CO2 concentration: ice core
From Our Changing Planet, Mackenzie, 1997

16. Sources of methane:
Decay of organic material in rice paddies, swamps, termite guts, oil and coal production, continental shelf.
Earth Science, Tarbuck & Lutgens, 2000

17. Vostok ice core record CO2 Temperature Methane
From Our Changing Planet, Mackenzie, 1997

18. Putting off the next glaciation for 1000 years?
Future effects:
Putting off the next glaciation for 1000 years?
From Our Changing Planet, Mackenzie, 1997

19. Effects of global warming?
Sea level rises.
Earth Science, Tarbuck & Lutgens, 2000

20. Future effects: Rising temperatures?
From Our Changing Planet, Mackenzie, 1997

21. Ozone and the Antarctic ozone hole:
Ozone protects us from harmful UV solar radiation
Ozone is created and destroyed naturally in the stratosphere.
However, anthropogenic chemical compounds, such as:
CFC-11, CFC-12 chlorofluorocarbons (amongst many others!)
act as a catalyst in the depletion of ozone.

22. From Our Changing Planet, Mackenzie, 1997

23. Chlorine or Bromine or Nitrogen
Ingredients:
Chlorine or Bromine or Nitrogen
UV solar radiation
From Our Changing Planet, Mackenzie, 1997

24. Other ingredients:
Polar stratospheric clouds - generated in the austral winter
Polar vortex -

26. Mt. Pinatubo

27. Ozone movie
From Our Changing Planet, Mackenzie, 1997