1. Air Issues Atmosphere basics Air pollution Climate change

2. Composition of atmosphere 78% nitrogen 21% oxygen 1% everything else

3. Structure of atmosphere Mesosphere and thermosphere 52-120 km Stratosphere 12-52 km temperature increases upward important ozone layer (19-26 km) Troposphere ground to 12 km temperature decreases upward

5. Focus on troposphere Our weather Pollution that affects humans Usual conditions vs. inversions (change in temperature going upward)

6. Usual conditions – pollution rises Inversion – pollution is trapped

7. Air pollution Outdoor air pollution Indoor air pollution

8. Criteria air pollutants (Clean Air Act, EPA) Carbon monoxide NO x or nitrogen dioxide SO 2 (sulfur dioxide) tropospheric ozone (O 3 ) particulate matter (PM) lead (Pb) Let’s look at sources of each of these.

9. Carbon monoxide (CO) Incomplete combustion of coal gasoline (catalytic converters help here) Why is it harmful to humans?

10. Nitrogen oxides (many forms) NO x Incomplete burning of gasoline Contributes to acid rain Part of ozone problem in summer in cities

11. Tropospheric Ozone Secondary pollutant Monitor VOCs (volatile organic compounds) solvents and vehicle emissions particularly important Often a summer-time problem

12. Sulfur dioxide (SO 2 ) Burning of coal Volcanic emissions (natural) Effects: damages plant chlorophyll, irritates throat and lungs; causes acid rain

13. Particulate matter Incomplete combustion of fossil fuels Dust from fields, construction, etc. Size of particles important What ARE those particles?

14. Lead Primary source from leaded gasoline Metal processing industries Effects central nervous system and bioaccumulates

15. Criteria Air pollutants Primary sources to atmosphere Carbon Monoxide Sulfur Dioxide Nitrogen Dioxide Tropospheric Ozone Particulate Matter Lead

16. Secondary pollutants Created by a reaction Includes smog and tropospheric ozone

17. Smog Photochemical smog (LA smog) Industrial smog (London smog)

18. Photochemical smog (1) Car exhaust Hydrocarbons and NO x plus solar radiation produces toxic chemicals, particularly ozone Higher ozone concentrations in late summer afternoons

19. Photochemical smog (2) Effects of ozone: Solutions:

20. Ozone (O 3 ) Stratosphere = good; troposphere = bad Part of summertime smog Charlotte area (and many other urban areas) are in non-attainment for ozone levels

21. Industrial smog Older industrial cities Often associated with coal burning Particulates, sulfur dioxide and stagnant air

22. Acid deposition Sulfuric and nitric acids Travel long distances Some solutions: industrial scrubbers, catalytic converters

23. Indoor air quality Increasing awareness Developing countries: particulate matter and carbon monoxide Industrialized nations: cigarette smoke, radon, mold, VOCs Solutions?

24. Global air issues Stratospheric ozone depletion Climate change

25. Stratospheric Ozone Depletion What does stratospheric ozone do? What is happening?

26. mid 1990s 1970s

27. Antarctic Researchers Routinely monitor atmosphere above Antarctica Significant depletion started in 1980

28. Rowland and Molina Predicted CFCs would destroy ozone (1974) CCl 2 F 2 + UV Cl + CClF 2 Cl + O 3 ClO + O 2 ClO + OO 2 + Cl

29. What can we do? Phase out manufacturing of CFCs – done Phase out use of CFCs – spray cans, styrofoam products, refrigerants – done Can this happen on a global basis?

30. Montreal Protocol (1987) Major reduction in production of CFCs and halons Initially signed by 25 nations, eventually ratified by over 150 nations CFC production in industrial nations to be cut by 50% Halon production frozen at 1986 levels SUCCESS

31. NATURAL TEMPERATURE VARIABILITY INCLUDING GREEN HOUSE EFFECT HUMAN IMPACT ON TEMPERATURES ADAPTATION, MITIGATION, SUFFERING Climate Change

32. Natural Temperature Variability Seasons Latitudes - altitudes Milankovitch cycles El Nino cycles

33. How do we know temperatures from long ago? Human records: actual measurements Proxies: ice cores, sediment cores for example

34. Greenhouse effect What is it? Is it bad or good that Earth has a greenhouse effect? Greenhouse gases

35. Sources of greenhouse gases Carbon dioxide : burning fossil fuels and forests, making cement Methane: decomposition of organic matter in swampy environments; frozen in tundra and ocean floor; stomachs of cows Nitrous oxides: bacterial decomposition of manure; soil denitrification; some organic fertilizers Halocarbons (including CFCs): chemical cooling agent; foaming agent; propellant (phased out by Montreal Protocol)

36. Relative strength of GHG (from IPCC, 2007) Carbon Dioxide1 Methane25 Nitrous oxide300 1 CFC replacement15,000

37. Future of global warming? Computer modeling United Nations IPCC

38. Intergovernmental Panel on Climate Change Won the Nobel Peace Prize (along with Al Gore) Established in 1988 2,000 scientists from many nations Policy-relevant but policy neutral Four assessment reports (latest in 2007)

39. IPCC Fourth Assessment Report Conclusions Greenhouse gases such as carbon dioxide help trap heat near Earth’s surface.

40. IPCC Fourth Assessment Report Conclusions “Global atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre- industrial values determined from ice cores spanning many thousands of years.” Highest in 650,000 years Today = 385 ppm Preindustrial = 280 ppm

41. “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.” IPCC Fourth Assessment Report Conclusions

42. Future? Sea level change (3-20 ft rise) Coral reef “bleaching” Changes in locations of plants and animals Melting of ice caps and glaciers

44. Sea Ice in Arctic Ocean 1979 and 2003

45. Alaskan glacier 1914 and 2004

46. Solutions? Adaptation Mitigation Suffering is inevitable, but how much?

47. Evaluating Solutions The Need for Adaptation We are already committed to a certain amount of warming Resources must be devoted to adapting to altered future conditions Sea level Ecosystems Focus on mitigation cannot ignore need for adaptation

48. Mitigation? Limit dependence on fossils fuels Plant trees Kyoto Protocol and beyond