1. Atmospheric and Climate Change
Chapter 13

2. 13-1 Climate and Climate Change
Objectives
1. Explain the difference between weather and climate.
2. Identify four factors that determine climate.
3. Explain why different parts of the earth have different climates.
4. Explain what causes the seasons.

3. What Factors determine climate?
Climate-long term prevailing weather (state of the atmosphere)
Determined by:
Latitude, atmospheric conditions, circulation patterns, oceanic patterns, local geography, solar activity, and volcanic activity.

4. Latitude
Amount of solar energy that reaches the surface

5. Atmospheric circulation
Warm air rises, cold air sinks
Warm air holds more moisture
Heat differences cause winds

6. Global Circulation Patterns
Patterns are disrupted at the equator
Cool air rises at the equator and is forced to the poles
Air condenses and 30 degrees N and S
Air sinks, causes water to evaporate from land
Flows back to the poles or equator

7. Prevailing winds (westerlies)
Blow from one direction most of the year
Trade winds at 30 degrees N and S

8. Ocean Circulation patterns
Hold vast amounts of heat
Currents redistribute heat
Cold and warm currents

9. El Nino – Southern Oscillation
Short-term periodic change in the location of warm and cold currents in the Pacific ocean
Winds in west Pacific become stronger and push warm water eastward
Causes drought in Indonesia and Australia

10. Pacific Decadal oscillation
La Nina -
Water in the Pacific is colder than usual
Pacific Decadal oscillation
Long term change in currents

12. Local geography
Mountain ranges
Seasonal changes

13. Solar activity
Increase UV and energy from the sun

14. Volcanic activity
Releases gases (SO2)and dust into the atmosphere which affects weather

15. 13-2 Ozone Shield Objectives
1. Explain how the ozone layer shields the Earth from much of the sun’s harmful radiation.
2. Explain how chlorofluorocarbons damage the ozone layer.
3. Explain the process by which the ozone hole forms.
4. Describe the damaging effects of ultraviolet radiation.
5. Explain why the threat to the ozone layer is still continuing today.

16. Ozone layer – ozone is concentrated
Ozone Shield
Ozone layer – ozone is concentrated O3
Absorbs UV – protects DNA of all living things

17. Chemicals that cause Ozone depletion
CFC’s (chlorofluorocarbons) damages ozone
Stable at surface but reacts in atmosphere
destroys ozone molecules

18. Ozone hole Thinning of atmospheric ozone that occurs at the poles
First report in 1985, but noticed in 1970’s

19. Chlorine reacts with ozone and destroys it
Form in polar stratospheric clouds
Can’t be replaced by ground level ozone

20. Affects
Increased UV radiation
Damages DNA
Cancer
Weaker immune system

21. Kills phytoplankton
Harms amphibians, marine life, and plants

22. International agreements (Montreal Protocol) to eliminate CFC use
Protection of Ozone
International agreements (Montreal Protocol) to eliminate CFC use
US pledged to ban all substances by 200
Did we do it??
Level is going down

23. It will be years before affects of programs can be measured because CFCs stay active for years

24. 13-3 Global Warming Objectives
1. Explain why Earth’s atmosphere is like the glass in a greenhouse.
2. Explain why carbon dioxide in the atmosphere appears to be increasing.
3. Explain why many scientists think that the Earth’s climate may be becoming increasingly warmer.
4. Describe what a warmer Earth might be like.

25. Greenhouse affect Traps sun energy
Major greenhouse gases (absorb and radiate heat):
Water vapor, CO2, CFCs, methane, and nitrous oxides

27. Keeling
Started measuring CO2 levels
1958 – 314 ppm
2000 – 368 ppm
Increased use of fossil fuels
Levels have normal seasonal fluctuations

28. Glaciers and poles melt
Increase of CO2 could cause a global rise in temperature (global warming)
Glaciers and poles melt
Sea level rise

29. Affects
Increase of global temperature
Rise of sea level
Loss of coastline
Agriculture
Droughts or too much rain

30. Some scientists believe that the warming is part of natural climatic variability
What is the evidence?

31. Consequences of a Warmer Earth
These things could happen rather caused by nature or man….
Melting of ice and sea level rise
Global weather patterns change
Human health problems
Agriculture
Plants and animals

32. How do we reduce the risk?
Reforestation
Reduce dependence of on fossil fuels
Reduce use of harmful chemicals
International agreements -
Kyoto Protocol