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Global Warming - PowerPoint PPT Presentation

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Global Warming
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  1. Global Warming Will Human-Induced Climate Change Destroy the World? .

  2. Introduction • Is the world getting warmer? • If so, are the actions of mankind to blame for earth’s temperature increases? • What can/should be done about these issues? • Are the potential resolutions worth the cost to implement them?

  3. History of Earth’s Climate • Earth formed ~4.6 billion years ago • Originally very hot • Sun’s energy output only 70% of present • Liquid water present ~4.3 billion years ago (zircon dating) • Much of earth’s early history erased during late heavy bombardment (~3.9 billion years ago)

  4. History of Earth’s Climate • Life appeared ~3.8 billion years ago • Photosynthesis began 3.5-2.5 billion years ago • Produced oxygen and removed carbon dioxide and methane (greenhouse gases) • Earth went through periods of cooling (“Snowball Earth”) and warming • Earth began cycles of glacial and interglacial periods ~3 million years ago

  5. Sun Solar Energy Solar Energy Earth’s Temperature

  6. Sun Solar Energy Radiative Cooling Earth’s Temperature

  7. Sun Solar Energy Radiative Cooling Earth’s Temperature

  8. Sun Solar Energy Radiative Cooling Earth’s Temperature

  9. Sun Greenhouse Effect

  10. Nitrogen (N2) Oxygen (O2) Argon (Ar) Water (H2O) Carbon Dioxide (CO2) Methane (CH4) Earth’s Atmospheric Gases Non-Greenhouse Gases >99% Greenhouse Gases <1%

  11. Sun Venus Runaway Greenhouse Effect • 97% carbon dioxide • 3% nitrogen • Water & sulfuric acid clouds • Temperature:860°F

  12. Carbon Dioxide

  13. Carbon Dioxide Levels Muana Loa Readings CO2 Levels Since 1958 370 350 CO2 (ppm) 330 310 40 30 20 10 0 420 370 320 CO2 (ppm) 270 220 Dome Concordia Vostok Ice Core 170 600000 400000 200000 0 Time (YBP)

  14. Future Carbon Dioxide Levels • Increasing CO2 emissions, especially in China and developing countries • Likely to double within 150 years: • Increased coal usage • Increased natural gas usage • Decreased petroleum usage (increased cost and decreasing supply)

  15. Past Temperatures

  16. Recorded Worldwide Temperatures Decreasing Flat Flat 0.8 0.6 0.4 0.2 D Mean Temperature (°C) 0.0 -0.2 -0.4 -0.6 1880 1900 1920 1940 1960 1980 2000 Year

  17. 2009 Temperature Changes Compared to 1951-1980 -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1 2009 Temperature Changes Compared to 1951-1980

  18. Past Temperatures Measurement • Proxy – a method that approximates a particular measurement (e.g., temperature) • Tree rings • Ice cores • Pollen records • Plant macrofossils • Sr/Ca isotope data • Oxygen isotopes from speleothem calcite (stalactites and stalagmites)

  19. Temperature History of the Earth • Little ice age (1400-1840) – 1°C cooler • Medieval warm period (800-1300) – 1°C warmer than today • Cool/warm cycles occur ~1,500 years • Affect mostly Northeastern U.S. and North Atlantic • Mostly due to changes in thermohaline circulation  • Dramatic shutdown of thermohaline circulation occurred 8,200 years ago as a large lake in Canada flooded the North Atlantic

  20. Main Ocean Currents Adapted from IPCC SYR Figure 4-2

  21. Temperature History of the Earth • For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods • These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity

  22. Orbital Parameters: Precession Perihelion Apehelion

  23. 22.5° 24.5° Orbital Parameters: Obliquity

  24. Apehelion Apehelion Perihelion Orbital Parameters: Eccentricity Maximum: 0.061 Minimum: 0.005 Not to scale! To Scale!

  25. Temperature History of the Earth • For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods • Last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago

  26. Temperature History of the Earth Middle Pliocene (3.15 to 2.85 million ya) • Temperatures: 2°C higher than today. • 20°C higher at high latitudes • 1°C higher at the Equator • Sea levels were 100 ft higher • Causes • CO2 levels that were 100 ppm higher • Increased thermohaline circulation

  27. Temperature History of the Earth Eocene (41 million years ago) • Opening of the Drake Passage (between South America and Antarctica). • Increased ocean current exchange • Strong global cooling • First permanent glaciation of Antarctica ~34 million years ago

  28. Temperature History of the Earth Paleocene Thermal Maximum (55 mya) • Sea surface temperatures rose 5-8°C • Causes • Increased volcanism • Rapid release of methane from the oceans

  29. Temperature History of the Earth Mid-Cretaceous (120-90 mya) • Much warmer • Breadfruit trees grew in Greenland • Causes • Different ocean currents (continental arrangement) • higher CO2 levels (at least 2 to 4 times higher than today, up to 1200 ppm)

  30. Recent Temperature Changes

  31. What Influences Tree Rings? • Temperature • Rainfall • Carbon dioxide concentration

  32. Consequences of Global Warming

  33. 2009 Temperature Changes Compared to 1951-1980 -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1

  34. Ice Sheets Melting? • GRACE (gravity measured by satellite) found melting of Antarctica equivalent to sea level rise of 0.4 mm/year (2 in/century) • Zwally, 2005 (satellite radar altimetry) • confirmed Antarctica melting • Greenland ice melting onexterior, accumulating inland(higher precipitation)

  35. Melting Glaciers – Mt. Kilimanjaro

  36. Changes in Antarctica Ice Mass 1000 800 600 400 200 Ice Mass (km3) 0 -200 -400 -600 2004 2003 2005 Year

  37. Rise in Sea Levels? • Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century) • Accelerating at a rate of 0.013 ± 0.006 mm/yr2 • If acceleration continues, could result in 12 in/century sea level rise • Scenarios claiming 1 meter or more rise are unrealistic

  38. Sea Levels for 450,000 Years 31 20 0 30 -20 29 -40 Sea Level (m) 28 SST (°C) Tropical Pacific -60 27 -80 26 -100 -120 25 450 400 350 300 250 200 150 100 50 0 Time (KYBP)

  39. 15 Data Unreliable 10 SST/SPDI (meters3/sec2) 5 Scaled August-OctoberSea-Surface Temperature Adjusted Atlantic StormPower Dissipation Index 0 1860 1880 1900 1920 1940 1960 1980 2000 2020 Increase in Hurricanes? • Two studies showed the total number of hurricanes has not changed • However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones) • Probably due to higher sea surface temperatures (more energy) • Difficult to know if this trend will continue

  40. How Much Temperature Increase? • Some models propose up to 9°C increase this century • Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C • Another study puts the minimum at 2.5°C

  41. Wildlife Effects • Polar Bears • Require pack ice to live • Might eventually go extinct in the wild • Sea turtles • Breed on the same islands astheir birth • Could go extinct on some islandsas beaches are flooded • Other species may go extinct as rainfall patterns change throughout the world

  42. Effect on Humans • Fewer deaths from cold, more from heat • Decreased thermohaline circulation • Cooler temperatures in North Atlantic • CO2 fertilization effect • Precipitation changes • Droughts and famine (some areas) • Expanded arable land in Canada, Soviet Union

  43. -50 -20 -10 -5 5 10 20 50 Potential Worldwide Precipitation Changes

  44. Drought in Africa Lake Faguibine Lake Chad

  45. Possible Solutions to Global Warming

  46. Mitigation of Global Warming • Conservation • Reduce energy needs • Recycling • Alternate energy sources • Nuclear • Wind • Geothermal • Hydroelectric • Solar • Fusion?

  47. Storage of CO2 in Geological Formations • Depleted oil and gas reservoirs • CO2 in enhanced oil and gas recovery • Deep saline formations – (a) offshore (b) onshore • CO2 in enhanced coal bed methane recovery 4 1 3b 3a 2 Adapted from IPCC SRCCS Figure TS-7

  48. Global Warming Myths

  49. Global Warming is Due to Urban Heat Islands -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1 2009 Temperature Changes Compared to 1951-1980

  50. Mt. Kilimanjaro’ Glaciers are Melting Because of Global Warming