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Air Issues

Air Issues. Atmosphere basics Air pollution Climate change. Composition of atmosphere. 78% nitrogen 21% oxygen 1% everything else. Structure of atmosphere. Mesosphere and thermosphere 52-120 km Stratosphere 12-52 km temperature increases upward important ozone layer (19-26 km)

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Air Issues

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  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

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

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

  6. Air pollution • Outdoor air pollution • Indoor air pollution

  7. Criteria air pollutants (Clean Air Act, EPA) • Carbon monoxide • NOx or nitrogen dioxide • SO2 (sulfur dioxide) • tropospheric ozone (O3) • particulate matter (PM) • lead (Pb) Let’s look at sources of each of these.

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

  9. Nitrogen oxides (many forms) • NOx • Incomplete burning of gasoline • Contributes to acid rain • Part of ozone problem in summer in cities

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

  11. Sulfur dioxide (SO2) • Burning of coal • Volcanic emissions (natural) • Effects: damages plant chlorophyll, irritates throat and lungs; causes acid rain

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

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

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

  15. Smog • Photochemical smog (LA smog) • Industrial smog (London smog)

  16. Photochemical smog (1) • Car exhaust • Hydrocarbons and NOx plus solar radiation produces toxic chemicals, particularly ozone • Higher ozone concentrations in late summer afternoons

  17. Photochemical smog (2) • Effects of ozone: • Solutions:

  18. Ozone (O3) • Stratosphere = good; troposphere = bad • Part of summertime smog • Charlotte area (and many other urban areas) are in non-attainment for ozone levels

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

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

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

  22. Global air issues • Stratospheric ozone depletion • Climate change

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

  24. mid 1990s 1970s

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

  26. Rowland and Molina • Predicted CFCs would destroy ozone (1974) • CCl2F2 + UV Cl + CClF2 • Cl + O3 ClO + O2 • ClO + O O2 + Cl

  27. 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?

  28. 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

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

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

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

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

  33. 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)

  34. Relative strength of GHG (from IPCC, 2007)

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

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

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

  38. 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.” Today = 385 ppm Preindustrial = 280 ppm Highest in 650,000 years

  39. IPCC Fourth Assessment Report Conclusions “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.”

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

  41. Sea Ice in Arctic Ocean 1979 and 2003

  42. Alaskan glacier1914 and 2004

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

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

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

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