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  • Insert cover image for Chapter 8 (p. 199).
  • Insert Figure 8.1a
  • Insert Figure 8.1
  • Insert Figure 8.2
  • Insert Table 8.1
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  • Insert Figure 8.4 and 8.5
  • Insert Figure 8.6 (p. 206)
  • Insert Figure 8.6 (p. 207)
  • Insert Figure 8.7 and 8.8
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  • Transcript

    • 1. Chapter 8: Global Climates and Climate Change Physical Geography Ninth Edition Robert E. Gabler James. F. Petersen L. Michael Trapasso Dorothy Sack
    • 2. Climate What is the difference between weather and climate? Arctic Sea ice changes: 1977 (top) to 2007 (bottom)
    • 3. 8.1 Classifying Climates <ul><li>Early Greeks (Aristotle): Torrid, Temperate, and frigid </li></ul><ul><li>Two weather variables most often used today: </li></ul><ul><ul><li>Temperature (minimum of 30 years of data) </li></ul></ul><ul><ul><li>Precipitation (minimum of 30 years of data) </li></ul></ul><ul><li>Classify Climate </li></ul><ul><ul><li>Atmospheric elements (statistics and math) = empirical </li></ul></ul><ul><ul><li>Based on the cause = genetic </li></ul></ul>
    • 4. 8.1 Classifying Climates <ul><li>Thornthwaite System </li></ul><ul><ul><li>Classifying based on moisture </li></ul></ul><ul><ul><li>Used often by soil and water resource scientists </li></ul></ul><ul><ul><li>Potential evapotranspiration </li></ul></ul><ul><ul><li>Actual evapotranspiration </li></ul></ul>
    • 5. 8.1 Classifying Climates What can you suggest are the causes for the major climate changes as you follow the 40 o latitude line from west to east?
    • 6. 8.1 Classifying Climates What is the Thornthwaite climate type for coastal California?
    • 7. 8.1 Classifying Climates <ul><li>Köppen System </li></ul><ul><ul><li>Most widely used </li></ul></ul><ul><ul><li>Based on regional temperature and precipitation </li></ul></ul><ul><ul><li>Advantages: </li></ul></ul><ul><ul><ul><li>Easy to measure </li></ul></ul></ul><ul><ul><ul><li>Measured most often </li></ul></ul></ul><ul><ul><ul><li>Most important </li></ul></ul></ul><ul><ul><li>Disadvantages: </li></ul></ul><ul><ul><ul><li>Only average monthly temp and precip. </li></ul></ul></ul><ul><ul><ul><li>Ignored winds, clouds, intensity of precip. </li></ul></ul></ul>
    • 8. 8.1 Classifying Climates <ul><li>Simplified Köppen System </li></ul><ul><ul><li>Divided into six major climate zones </li></ul></ul><ul><ul><ul><li>A = Humid Tropical </li></ul></ul></ul><ul><ul><ul><li>C = humid mesothermal (mild winter) </li></ul></ul></ul><ul><ul><ul><li>D = humid microthermal (severe winter) </li></ul></ul></ul><ul><ul><ul><li>E = polar </li></ul></ul></ul><ul><ul><ul><li>BW and BS = arid and semiarid </li></ul></ul></ul><ul><ul><ul><li>H = Highland </li></ul></ul></ul>
    • 9. 8.1 Classifying Climates Simplified Köppen System
    • 10. 8.1 Classifying Climates <ul><li>Tropical (A) Climate </li></ul><ul><ul><li>High temp year round </li></ul></ul><ul><ul><li>Near equator </li></ul></ul><ul><ul><li>No winter season (average temp of coldest month above 18 o C (64.4 o F) </li></ul></ul><ul><ul><li>ITCZ </li></ul></ul><ul><ul><li>Af (tropical rainforest) </li></ul></ul>
    • 11. 8.1 Classifying Climates <ul><li>Tropical (A) Climate </li></ul><ul><ul><li>Aw (dry winter tropical savanna) </li></ul></ul><ul><ul><li>Am (along coast with tropical monsoon) </li></ul></ul>
    • 12. 8.1 Classifying Climates World Map of modified Köppen Classification System
    • 13. 8.1 Classifying Climates World Map of modified Köppen Classification System
    • 14. 8.1 Classifying Climates <ul><li>Polar (E) Climate </li></ul><ul><ul><li>No month has an average temp grater than 10 o C (50 o F) </li></ul></ul><ul><ul><li>EF (ice sheet): no month > 0 o C </li></ul></ul><ul><ul><li>ET (tundra): at least 1 month averages > 0 o C </li></ul></ul>
    • 15. 8.1 Classifying Climates <ul><li>Mesothermal (C) Climate </li></ul><ul><ul><li>1 month below average temp grater than 18 o C (64.4 o F) and 1 month below 10 o C (50 o F) </li></ul></ul><ul><ul><li>Csa and Csb (Mediterranean) </li></ul></ul><ul><ul><ul><li>Dry summer </li></ul></ul></ul><ul><ul><ul><li>Along west coasts between 30 o and 40 o latitude </li></ul></ul></ul><ul><ul><li>Cfa (humid subtropical) </li></ul></ul><ul><ul><ul><li>Wet year round </li></ul></ul></ul><ul><ul><ul><li>Southeast U.S. </li></ul></ul></ul>
    • 16. 8.1 Classifying Climates <ul><li>Mesothermal (C) Climate </li></ul><ul><ul><li>Cfb and Cfc (marine west coast) </li></ul></ul><ul><ul><li>Wet year round </li></ul></ul><ul><ul><li>Summer’s cooler than Cfa </li></ul></ul><ul><ul><li>Along west coasts often extending up to 40 o latitude </li></ul></ul>
    • 17. 8.1 Classifying Climates <ul><li>Microthermal (D) Climates </li></ul><ul><ul><li>Usually year round precip. </li></ul></ul><ul><ul><li>Shorter summers and colder winters than “C” </li></ul></ul><ul><ul><li>Found only in N. hem. </li></ul></ul><ul><ul><li>Dfa and Dwa (humid continental, hot summer) </li></ul></ul><ul><ul><li>Dfb and Dwb (humid continental, mild summer) </li></ul></ul><ul><ul><li>Dfc, Dfd, Dwc, and Dwd (subarctic) </li></ul></ul>
    • 18. 8.1 Classifying Climates <ul><li>Arid (B) Climates </li></ul><ul><ul><li>Year round moisture deficiency </li></ul></ul><ul><ul><li>Precip received < potential ET </li></ul></ul><ul><ul><li>15 o to 30 o latitude </li></ul></ul><ul><ul><li>BW (desert, annual precip. is less than half of annual potential ET) </li></ul></ul><ul><ul><li>BS (steppe; annual precip. is less than potential ET, but more than half) </li></ul></ul>
    • 19. 8.1 Classifying Climates <ul><li>Highland (H) Climates </li></ul><ul><ul><li>Mountain barriers can increase and decrease precipitation, cloud cover, and temperature. </li></ul></ul><ul><ul><li>Windward – wetter </li></ul></ul><ul><ul><li>Temperature decreases as you increase in elevation. </li></ul></ul>
    • 20. 8.1 Classifying Climates <ul><li>Climate Regions </li></ul><ul><ul><li>Region: similar internal characteristics distinct from other areas. </li></ul></ul><ul><ul><li>Transition </li></ul></ul><ul><li>Scale of Climate </li></ul><ul><ul><li>Microclimate </li></ul></ul><ul><ul><li>Topoclimates </li></ul></ul><ul><ul><li>Lake effect snow </li></ul></ul><ul><ul><li>Urban heat-island effect </li></ul></ul>
    • 21. 8.2 Climates of the Past <ul><li>Ice Ages </li></ul><ul><ul><li>Glaciation (cold period) </li></ul></ul><ul><ul><li>Interglacial (warmer period) </li></ul></ul><ul><ul><li>Pleistocene </li></ul></ul><ul><ul><li>Q: Why does the ice move in various directions in difference regions of the continent? </li></ul></ul>
    • 22. 8.2 Climates of the Past <ul><li>Modern Research </li></ul><ul><ul><li>Radiometric techniques </li></ul></ul><ul><ul><li>Ocean sediment </li></ul></ul><ul><ul><ul><li>Calcium carbonate and shells </li></ul></ul></ul><ul><ul><ul><li>Oxygen-isotope record </li></ul></ul></ul><ul><ul><li>Holocene </li></ul></ul>
    • 23. 8.2 Climates of the Past <ul><ul><li>Q: Has the general trend of temperature on Earth been warmer or colder during the Holocene? </li></ul></ul>
    • 24. 8.2 Climates of the Past <ul><li>Methods for Revealing Climates of the Past </li></ul><ul><ul><li>Paleoclimates </li></ul></ul><ul><ul><li>Oxygen-Isotope Ratio of Calcium carbonate and shells </li></ul></ul><ul><ul><li>Ice cores </li></ul></ul><ul><ul><li>Dendrochronology </li></ul></ul><ul><ul><li>Palynology </li></ul></ul>
    • 25. 8.2 Climates of the Past <ul><li>Methods for Revealing Climates of the Past (con’t) </li></ul><ul><ul><li>Palynology: </li></ul></ul><ul><ul><ul><li>pollen-analysis </li></ul></ul></ul><ul><ul><ul><li>A core is drilled and removed to show the layers of the sediment. </li></ul></ul></ul><ul><ul><ul><li>Organic material can be radiocarbon dated. </li></ul></ul></ul><ul><li>Paleoclimatologists reconstruct the climate </li></ul>
    • 26. 8.3 Rates of Climate Change <ul><li>Altithermal </li></ul><ul><ul><li>7000 ya (years ago) </li></ul></ul><ul><ul><li>Warmer than today </li></ul></ul><ul><li>What was the evidence? </li></ul><ul><ul><li>Ice record from Antarctica and Greenland (oxygen-isotope. </li></ul></ul><ul><ul><li>Rapid change (few years or a decade) </li></ul></ul><ul><ul><li>Positive feedback system </li></ul></ul>
    • 27. 8.4 Causes of Climate Change <ul><li>Orbital Variations (Milankovitch Cycles) </li></ul><ul><ul><li>Eccentricity: </li></ul></ul><ul><ul><ul><li>100,000 years </li></ul></ul></ul><ul><ul><ul><li>Shape of Earth’s orbit </li></ul></ul></ul><ul><ul><li>Obliquity </li></ul></ul><ul><ul><ul><li>41,000 years </li></ul></ul></ul><ul><ul><ul><li>Tilt of Earth’s axis 24.5 o - 22 o </li></ul></ul></ul><ul><ul><li>Precession </li></ul></ul><ul><ul><ul><li>21,000 years </li></ul></ul></ul><ul><ul><ul><li>Distance to the sun </li></ul></ul></ul>
    • 28. 8.4 Causes of Climate Change <ul><li>Changes in Earth’s Atmosphere </li></ul><ul><ul><li>Volcanic Activity </li></ul></ul><ul><ul><ul><li>Tambora (1815, 1816) </li></ul></ul></ul><ul><ul><ul><li>Krakatoa (1883) </li></ul></ul></ul><ul><ul><ul><li>Mount Pinatubo (1991) </li></ul></ul></ul><ul><ul><li>Greenhouse Gases </li></ul></ul>
    • 29. 8.4 Causes of Climate Change <ul><li>Greenhouse Gases </li></ul><ul><ul><li>Carbon Dioxide (CO 2 ) </li></ul></ul><ul><ul><ul><li>Blocks outgoing longwave radiation </li></ul></ul></ul><ul><ul><ul><li>CO 2 and ice sheets </li></ul></ul></ul><ul><ul><ul><li>Increasing trend (~ 380 ppm as of 2007). </li></ul></ul></ul><ul><ul><li>Methane (CH 4 ) </li></ul></ul><ul><ul><ul><li>Very effective, however, currently very low. </li></ul></ul></ul><ul><ul><li>CFC’s </li></ul></ul><ul><ul><li>Nitrous Oxides (N 2 O) </li></ul></ul>
    • 30. 8.4 Causes of Climate Change <ul><li>Which greenhouse gas has the longest residence time? </li></ul>
    • 31. 8.4 Causes of Climate Change <ul><li>Changes in the Ocean </li></ul><ul><ul><li>ENSO </li></ul></ul><ul><ul><li>Thermohaline Circulation </li></ul></ul><ul><li>Changes in Landmasses </li></ul><ul><ul><li>Shifting land masses (e.g. Continent over the poles) </li></ul></ul><ul><ul><li>New land blocking oceanic or atmospheric circulation </li></ul></ul><ul><ul><li>Change in albedo </li></ul></ul>
    • 32. 8.4 Causes of Climate Change <ul><li>Impact Events </li></ul><ul><ul><li>Asteroids </li></ul></ul><ul><ul><li>Comets </li></ul></ul><ul><ul><li>Tunguska Event </li></ul></ul><ul><ul><li>65 mya </li></ul></ul><ul><ul><li>Near Earth Objects (NEO) </li></ul></ul>
    • 33. 8.5 Predicting Future Climates <ul><li>Little Ice Age (1560-1850) </li></ul><ul><li>General Circulation Models (GCM’s) </li></ul><ul><li>Milankovitch Cycles </li></ul><ul><li>Greenhouse Gases </li></ul><ul><li>Global warming: most scientists believe that global warming is occurring. </li></ul>
    • 34. 8.5 Predicting Future Climates <ul><li>Global warming </li></ul><ul><ul><li>most scientists believe that global warming is occurring. </li></ul></ul><ul><ul><li>Most mountain glaciers are retreating </li></ul></ul>
    • 35. 8.6 The Issue of Global Warming <ul><li>The climate changes naturally </li></ul><ul><li>However, the vast majority of scientists content that humans are affecting our atmosphere. </li></ul><ul><li>IPCC (Intergovernmental Panel on Climate Change) </li></ul><ul><ul><li>“ very likely that emissions of greenhouse gases from anthropogenic activities have caused” … most of the observed increase in globally-averaged temperature since the mid-20 th century. </li></ul></ul>
    • 36. 8.6 The Issue of Global Warming <ul><li>On what continent has the observed temperature fluctuated the most during this time period, and which one the least? </li></ul>
    • 37. 8.6 The Issue of Global Warming <ul><li>Recommendations for the Future </li></ul><ul><ul><li>Global Scale </li></ul></ul><ul><ul><li>Simple things we can do that will help reduce our negative impact on Earth’s fragile environment: </li></ul></ul><ul><ul><ul><li>Use car pools and mass transit </li></ul></ul></ul><ul><ul><ul><li>Drive smaller cars </li></ul></ul></ul><ul><ul><ul><li>Use more energy-efficient lighting and appliances </li></ul></ul></ul><ul><ul><ul><li>Recycle </li></ul></ul></ul>
    • 38. Physical Geography End of Chapter 8: Global Climates and Climate Change

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