1. Chapter 20 The Atmosphere: Climate, Climate Change, and Ozone Depletion Copyright © 2008 Pearson Prentice Hall, Inc. Environmental Science Tenth Edition Richard T. Wright

2. Hurricane Katrina in Gulf of Mexico (August 28, 2005)

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

5. Atmosphere and Weather Atmospheric structure Weather

6. Atmospheric Structure

8. Some Terms Weather: day-to-day variations in temperature, air pressure, wind, humidity, and precipitation – all mediated by the atmosphere Climate: result of long-term weather patterns in a region Meteorology: scientific study of weather and climate

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

10. Weather: Convection Cell

11. Tornadoes Cold low pressure air mass collides with a warm high pressure air mass http://www.photolib.noaa.gov/nssl/nssl0065.htm

12. 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

13. 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

14. Climate Climates in the past Ocean and atmosphere

15. Climate Also 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

16. Identify Climates A to E Precipitation Temperature LowHigh A B C D E

17. Climates in the Past

19. Past Climates

20. El Niño: What Happened? Jet streams shifted from normal course. Cause unknown. AprilMay June

21. 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.

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

23. The El Niño Effects 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

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

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

26. The Oceanic Conveyor System

27. 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)

28. 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

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

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

31. The Earth as a Greenhouse

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

33. Greenhouse Gases: CO 2 Emissions from Fossil Fuel Burning 35% higher than before industrial revolution Oceans = CO 2 sink Forests = CO 2 source 24 billion metric tons CO 2 added each year

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

35. Intergovernmental Panel of Climate Change (IPCC): Fourth Assessment Assess scientific issues Evaluate the impact of global climate change and prospects for adapting to it Investigate ways of mitigating the effects

36. IPCC Assessments Third Assessment: Human activities are influencing global climate change Fourth Assessment: –global climate change is now occurring –caused by rising levels of anthropogenic greenhouse gases –global impacts will be unprecedented and severe

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 4.5 C o

38. Fourth Assessment CO 2 Concentrations

39. Sources of CO 2 Emissions

40. Global Carbon Cycle

42. Radiative Forcing

43. Heat Capture by the Ocean

44. Global Mean Sea Level

45. Muir Glacier in the Past

46. Muir Glacier Today

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

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

49. Reducing CO 2 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

50. Reducing CO 2 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

51. Key Findings of the Fourth Assessment Increased warming – climate change Differing regional impacts Heat waves more frequent and last longer Vulnerable ecosystems - arctic Widespread water concerns – increase in extremes (+ and -) of daily precipitation

52. Key Findings of the Fourth Assessment Agriculture largely unaffected Thermohaline conveyor system expected to slow down Rising sea levels Storm intensities expected to increase

53. Arctic Climate Impact Assessment Arctic climate is now warming rapidly Arctic warming and its consequences will have worldwide implications

54. Arctic Climate Impact Assessment Arctic vegetation zones will shift, and animal ranges and distribution will change Reduced sea ice likely to increase marine transport and access to resources Thawing ice will disrupt transportation, buildings, and other infrastructure

55. Decline of Arctic Sea Ice

56. Arctic Albedo Feedback

57. What About the Antarctic? Holds most of the world’s ice –Could be a huge factor in future sea level rise –Greenland and Antarctic ice sheets hold enough water to raise sea level by 230 feet Losing as much as 36 cubic miles of ice/year – enough to raise sea level by 0.4mm/year

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

59. Response I: Mitigation Framework Convention on Climate Change Kyoto Protocol U.N. Climate Control Conference U.S. Policy –Global Climate Change Initiative –Climate Change Science Program –National Climate Change Technology Initiative

62. Response 2: Adaptation Reduced crop yields Water scarcity Increased heat and moisture = > infectious diseases and lethal heat waves Increased intensity and severity of storm events Impoverished nations will be most affected – adaptation not an option

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

65. Good Ozone! Bad Ozone!

66. Electromagnetic Spectrum

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

68. Formation of the Ozone Shield Reaction #1: UV light + O 2 O + O Reaction #2: Free O + O 2 O3O3 Reaction #3: Free O + O 3 O 2 + O 2 Reaction #4: UV light + O 3 O + O 2

69. 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

70. Breakdown of Ozone Shield Reaction #5: CFCl 3 + UV Cl + CFCl 2 Reaction #6: Cl + O 3 ClO + O 2 Reaction #7: ClO + ClO 2Cl + O 2 Which reaction releases Cl from CFCs? Which reaction generates more Cl? Chlorine is a catalyst that destroys the production of ________?

72. Coming to Grips with Ozone Depletion Montreal Protocol: scale CFC production back 50% by 2000 Most industrialized countries no long produce or use CFCs

73. Ozone Loss and Extent of Ozone Hole

74. Ozone Hole: 11 million sq.mi.

75. Ozone-depleting substances production and presence in the atmosphere: past, present, and future CFCs HCFCs Relative abundances of chlorine and bromine in the stratosphere

76. 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”

77. End of Chapter 20 PPT by Clark E. Adams