1. Environmental Science: Toward a Sustainable Future Richard T. Wright
Chapter 20
The Atmosphere: Climate, Climate Change, and Ozone Depletion PPT by Clark E. Adams

2. El Niño: What Happened? Jet streams shifted from normal course
April
May
Jet streams shifted from normal course
Cause unknown
June

3. El Niño: What Happened?
Development of warm water in the eastern Pacific over time
Reversal in trade winds that normally blow from an easterly direction

4. El Niño: What Happened?
Warm water spread to the east
Global patterns in moisture and evaporation changed = climate shifts

5. The El Niño Effects: Fig. 20-1
Landslides on the California coast
Mildest hurricane season in many years
Rain five times normal in an East Africa drought region
Record crop harvests in India, Australia, and Argentina

6. La Niña: What Happened?
Easterly trade winds reestablished with greater intensity
Upwelling of colder water from ocean depths
Jet streams are weakened
Global patterns in moisture and evaporation return to “normal”

7. The Atmosphere: Climate, Climate Change, and Ozone Depletion
Atmosphere and weather
Climate
Global climate change
Response to climate change
Depletion of the ozone layer

8. Atmosphere and Weather
Atmospheric structure
Weather

9. Atmospheric Structure

11. Weather: Solar Energy Balance
Most solar energy absorbed by atmosphere,
oceans, and land

12. Weather: Convection Cell

13. Tornadoes
Cold low-pressure air mass collides with a warm high-pressure air mass

14. Fujita Scale Measures the Intensity of Tornadoes
F-0: 40–72 mph, chimney damage, tree branches broken
F-1: 73–112 mph, mobile homes pushed off foundations or overturned
F-2: 113–157 mph, considerable damage, mobile homes demolished, trees uprooted

15. Fujita Scale Measures the Intensity of Tornadoes
F-3: 158–205 mph, roofs and walls torn down, trains overturned, cars thrown
F-4: 207–260 mph, well-constructed walls leveled
F-5: 261–318 mph, homes lifted off foundation and carried considerable distances, autos thrown as far as 100 meters

16. Climate
Ocean and atmosphere
Climates in the past

17. Climate
Defined as the average trend in temperature and rainfall that produces a unique assemblage of plants and animals
On the next slide identify climates A to E, e.g., low average rainfall and high average temperature = hot desert

18. Identify Climates A to E
Temperature
Low
High A B C D E
Precipitation

19. Climates in the Past

20. Past Climates

21. Ocean and Atmosphere Covers 75% of the Earth’s surface
Major source of water to hydrologic cycle
Major source of heat to atmosphere
Stores and conveys heat

22. The Ocean Conveyor System

23. The Ocean Conveyor System
Thermohaline circulation: effects that temperature and salinity have on density of water
Conveyor system moves water masses from the surface to deep oceans and back again
Cool northern waters more dense and sink to depths of 4,000 m = North Atlantic Deep Water (NADW)

24. The Ocean Conveyor System
Deep water spreads southward to south Africa and joined by cold Antarctic waters
Spread northward into Indian and Pacific oceans as deep currents
Current slows down, warms up, becomes less dense, rises to the surface, and moves back to North Atlantic
Produces a warm climate in Europe

25. The Ocean Conveyor System
Factors that could alter the conveyor system
Appearance of unusually large quantities of freshwater – melting icebergs
Global warming

26. Global Climate Change The Earth as a greenhouse The greenhouse gases
Evidence of climate change

27. The Earth as a Greenhouse

28. Factors Affecting Global Temperatures
Cloud cover: cooling
Changes in Sun’s intensity: cooling or warming
Volcanic activity: cooling
Sulfate aerosols: cooling

29. Greenhouse Gases: CO2 Emissions from Fossil Fuel Burning
35% higher than before industrial revolution
Oceans = CO2 sink
Forests = CO2 source
24 billion metric tons CO2 added each year

30. Other Greenhouse Gases and Sources
Water vapor
Methane
Nitrous oxide
CFCs and other halocarbons
Hydrologic cycle
Animal husbandry
Chemical fertilizers*
Refrigerants*
* = Long residence times and contribute to
ozone depletion

31. Atmospheric CO2 Concentrations

33. Global Surface Temperatures

34. Global Carbon Cycle

35. Impacts of Global Warming
Melting of polar ice caps
Flooding of coastal areas
Massive migrations of people inland

36. Impacts of Global Warming
Alteration of rainfall patterns
Deserts becoming farmland and farmland becoming deserts
Significant losses in crop yields

37. Evidences of Climatic Change
17 of the hottest years on record have occurred since 1980 (Fig. 20-5)
Wide-scale recession of glaciers
Sea level rising
Predicted mean global temperature change
by 2100 is between 1.5 and 4.5oC

38. Reducing CO2 Emissions (True or False)
Reducing use of fossil fuels
Adopt a wait-and-see attitude
Develop alternative energy sources
Plant trees
Examine other possible causes of global warming

39. Reducing CO2 Emissions (True or False)
Make and enforce energy conservation rules
Rely on the government
Adopt the precautionary principle
Raise the minimum driving age to 18 years

40. Key Findings of the 2000 U.S. Climate Change Assessment (Table 20-3)
Increased warming
Differing regional impacts
Vulnerable ecosystems
Widespread water concerns
Agriculture largely unaffected
Forest growth to increase
Coastlines – rising sea levels

41. Responses to Climate Change
Response 1: mitigation = reduce CO2 emissions
Response 2: adaptation = accepting and learning to live with the consequences of climate change

42. Framework Convention on Climate Change (FCC)
Relied on voluntary approach to reduce CO2 emissions
Developing countries continue toward developed nation status using fossil fuels

43. Framework Convention on Climate Change (FCC)
To achieve a 7% reduction by 2010 requires a 25% reduction of present use
By 2010 CO2 emissions will have increased by 30%

44. Framework Convention on Climate Change (FCC)
Bottom line: need 60% reduction (144 ppm) in CO2 emission worldwide NOW to stabilize greenhouse gas concentrations at today’s levels

45. Depletion of Ozone Layer
Radiation and importance of the shield
Formation and breakdown of the shield
Coming to grips with ozone depletion

46. Good Ozone!
Bad Ozone!

47. Electromagnetic Spectrum

48. Radiation and Importance of the Shield
Skin cancer (700,000 new cases each year)
Premature skin aging
Eye damage
Cataracts
Blindness

49. Formation of the Ozone Shield
Reaction #1: UV light + O2
O + O
Reaction #2: Free O + O2 O3
Reaction #3: Free O + O3
O2 + O2
Reaction #4: UV light + O3
O + O2

50. Chlorofluorocarbons (CFCs)
Organic molecules in which both chlorine and fluorine atoms replace some of the hydrogen atoms
Sources:
refrigerators and air conditioners
production of plastic foam
cleaner for electronic parts
pressurizing agent in aerosol cans

51. Breakdown of Ozone Shield
Reaction #5: CFCl3 + UV
Cl + CFCl2
Reaction #6: Cl + O3
ClO + O2
Reaction #7: ClO + ClO
2 Cl + O2
Which reaction releases Cl from CFCs?
Which reaction generates more Cl?
Chlorine is a catalyst that destroys
the production of ________?

52. Montreal Protocol
1987 – scale back CFC production by 50% by 2000

53. Coming to Grips with Ozone Depletion: Montreal Protocol
1990 – amendment to completely phase out ozone-destroying chemicals by 2000
1992 – amendment to completely phase out ozone-destroying chemicals by 1996
Why the rush?

54. Ozone Hole: 11 million sq.mi.

55. The Clean Air Act of 1990: Title IV
Restricts production, use, emissions, and disposal of ozone-depleting chemicals
Regulates the servicing of refrigeration and air-conditioning units
“Protecting Stratospheric Ozone”

56. End of Chapter 20