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Global Climate Cycles, Global Warming and Anthropogenic Greenhouse Effect

Global Climate Cycles, Global Warming and Anthropogenic Greenhouse Effect. Important considerations regarding global warming and the anthropogenic greenhouse effect.

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Global Climate Cycles, Global Warming and Anthropogenic Greenhouse Effect

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  1. Global Climate Cycles,Global Warmingand Anthropogenic Greenhouse Effect

  2. Important considerations regarding global warming and the anthropogenic greenhouse effect • Cyclical Processes – The earths environmental conditions have been evolving through geologic time. They tend to be cyclical over both long and short periods of time and have changed character greatly and abruptly. • Chaos is an operating factor • Positive Feedback vs Negative Feedback

  3. Brief History of Earth • 4.5 b.y. ago earth formed from a cloud of dust and gas that circled proto-sun as a disc. • Luminosity of sun was about 30% less than present in early history, yet earth was as warm then as now. • Atmosphere had high content of CO2

  4. BBlack Dwarf WWhite Dwarf RRed Giant

  5. There have been multiple periods of major continental glaciation.

  6. Continental Glaciation Approx. Time of GlaciationDuration 2300 m.y. 200 m.y. 900 m.y. 50 m.y. 750 m.y. 50 m.y. 600 m.y 20 m.y. 450 m.y. 25 m.y. 300 m.y. 50 m.y. now about 10 m.y.so far

  7. Continental Glaciation in North America and Europe  began about 1.6 m.y. ago (Pleistocene or ice ages). • Glacial and interglacial periods cycle with a period of about 100,000 years. • Interglacial periods are about 10,000 years in duration

  8. First modern humans appeared about 200,000 years ago. • Peak of last glaciation occurred about 20,000 years ago. • Sea level was 400 feet lower • Long Island was not an Island then

  9. Shoreline 18,000 b.p

  10. Interglacial period began about 10,000 years ago. • We are presently in an interglacial period. • Agriculture started about 10,000 years ago.

  11. Past is key to the future

  12. What will Long Island or the earth be like in: • 12 hours? • 6 months? • 100 years? • 50,000 years? • 2 b.y.? • 5 b.y.? • 7 b.y.?

  13. What Controls Earth’s Surface Temperature?

  14. 10,000o F 60o F 0o F if no Greenhouse Effect www.ultranet.com/~jkimball/BiologyPages/ C/CarbonCycle.html

  15. Real-time measurements and historical records of climate (back to 1800’s; some earlier)

  16. ToC SGlobal Surface temperature

  17. GGlobal Surface TemperatureScientific American, March 2005 p. 35

  18. CClimate Northern Hemisphere Moberg et al, 2005 Nature v 433, p. 613-617

  19. Record from position of glaciers

  20. Rhone Glacier (Present)

  21. Rhone Glacier (Present)

  22. Lithograph from 1850’s

  23. Climate Northern Hemisphere Moberg et al, 2005 Nature v 433, p. 613-617

  24. 20,000-40,000 year cycles

  25. 100,000 year cycles

  26. GGreenhouse Gases

  27. Anthropogenic Greenhouse Gases • Carbon Dioxide 60% • Burning of Fossil Fuels • Deforestation • Methane 15% • Coal Mines • Termites • Wetlands (beavers) • Rice Patties • Cattle • Subpolar Soil and Wetlands • Methane hydrate

  28. Methane Hydrate • Immense Carbon reservoir • Twice as large as all known fossil fuels • Methane is 10 times more effective a greenhouse gas as carbon dioxide • Occurs on sea floor at depths greater than about 2,000 feet • In polar sediments

  29. Global Carbon Budget

  30. Methane Hydrate

  31. Locations where methane hydratehas been discovered

  32. Mean global temperature has increased since mid-1800’s • Has CO2 ? • Can we see correlations earlier? Glacier Ice.

  33. Projected Changes in Global Climate (Short-term)

  34. Ruddiman, 2005, Sci Am. March

  35. Ruddiman, 2005, Sci Am. March

  36. Ruddiman, 2005, Sci Am. March

  37. Consequences of Greenhouse Warming • Increase in warming • least in tropics • greatest toward poles.

  38. Consequences of Greenhouse Warming • Wandering weather patterns • Increased precipitation • Less rain in summer in U.S. midwest • Intensity and numbers of storms will increase • Ocean currents may be modified

  39. Consequences of Greenhouse Warming • Expansion of Oceans on heating • Melting of glaciers • Sea level rise of 1 to 3 feet by 2100 • More severe storms • Result will be coastal flooding

  40. Consequences of Greenhouse Warming • Natural Habitats will be destroyed • Forests dying • Wild animals unable to migrate development isolation • Areas with tropical diseases expand

  41. Agriculture may be helped or hurt depending on area and ability of farmers to react fast enough • Water for irrigation and human use may be inadequate for populations in drier areas

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