Past and Present Climates

1. Past and Present Climates Lynn Gribble 6/9/09

2. Eco Tip #8: Water • Up to 40% of bottled water comes from the same source as tap water, but is sold back to consumers at hundreds of times the cost. • More than 17 million barrels of oil last year were used to produce and transport bottled water – Enough fuel for more than 1 million U.S. cars for a year - and generated more than 2.5 million tons of carbon dioxide. ( http://www.thinkoutsidethebottle.org/ )

3. Climate • Defn: The collective state of the atmosphere for a given location over a specific amount of time • Location: global, hemispheric, continental, regional, city… • Time: usually however long there is an accurate record • Averages and extremes

4. Climate Controls (Review) • Latitude – distance from equator associated with warmer climate • Elevation – higher altitudes associated with colder temps • Topography – vegetation modulates temperature • Proximity to large bodies of water – coastal cities vary less in temperature • Prevailing atmospheric circulation

5. Climate Zones • Köppen Scheme: classification scheme which separates the globe into 24 climate zones. (6 main zones with sub-categories) Figure 14-3

6. Type A: Tropical Humid • High average temperature • Small annual temperature range • Abundant rainfall Figure 14-4

7. Type B: Dry Climates • Potential evaporation and transpiration exceeds precipitation • Includes both warm climates and cold ones (desserts and poles) Figure 14-5

8. Type C: Moist Subtropical and Mid Latitude • Humid and mild winters • Warm average temperature • Large annual temperature range Figure 14-6

9. Type D: Severe Mid-Latitude • Tend to be located in eastern regions of continents • Great temperature range • Usually have snow on the ground for extended periods Figure 14-10

10. Type E: Polar Climates • Pole-ward of the Arctic and Antarctic circle • Extremely cold with little precipitation (not considered dessert b/c precip>evap) Figure 14-12

11. Type F:Highland • Wide variety of climates due to wide variety of latitude, altitude, and exposure to solar energy • Various precipitation based on orientation

12. 5 Minute Break! • Exam #2 Thursday • Onwards to Past Climate  • (For a really easy, fun read about the past, I recommend “A Short History of Nearly Everything” by Bill Bryson)

13. Past Climate • Historical Climate: the period of the past in which humans have kept record of climate. • Instrumental Climate: the period of the past in which specialized scientific instruments were used to keep record of climate • Paleo-climate: climate records from pre-history

14. Tree Rings • Dendrochronology • Tree ring width varies due to temperature and moisture changes • Gives information about temperature and precip changes • Qualitative (relative) Figure 14-15

15. Pollen Records • Pollen Degrades slowly therefore this along with radio-carbon dating is a good proxy for climate records. • Also different • types of pollen • Gives information • about changing • plant types Figure 14-17

16. Air Bubbles and Dust in Ice • Accurate concentration of atmospheric gases from the past • Dust indicates volcanic activity, and source regions for air masses and therefore circulation patterns Figure 14-18

17. Marine Sediments and Fossils • Calcium Carbonate is useful for tracking relative amounts of oxygen isotopes (indicates relative cold or warm periods) • Plant and animal fossils give good idea of climate based on the type of life that a given time period supported

18. UAlbany studies in paleo-climate include: • John Delano (AGEO 105 – Intro to Envi Sci): • Early Earth Environments – how these environments impacted the evolution of sustainable life • Bombardment history • Brad Linsley (AGEO 450 – Climate Change): • Generation of time series from Pacific Ocean corals and sediment cores • Mathias Vuille: • Paleo-climatology in tropical mountain glaciers (Andes) • Glacial recession prediction

19. Change Mechanisms • Volcanic Eruptions lead to cooler climates. Why? Ash and soot from eruption block sloar radiation causing cooling • Asteroid Impacts , depending on impact location could cause extended darkness, global fires, acid rain, ozone loss, and huge tsunamis. • Solar Variability: 11 year sun spot cycle • Fewer sunspots = less energy, cooling • "Little Ice Age“ (~300 yrs ago) little to no sunspots

20. Change Mechanisms • Milankovitch Cycles • Eccentricity: Shape of earth’s orbit • 100,000 year cycle • Procession: “wobble” around axis of rotation • 23,000 year cycle • Tilt/Obliquity: change in angle of inclination • 41,000 year cycle

21. Change Mechanisms • Milankovitch Cycles • D:\Media\Active_Figures\71_Orbital_Fluctuations\A_71.html Figure 14-25A

22. Change Mechanisms • Changes in Ocean Currents • Plate Tectonics : continental movements • Pangea – Tropical , flat super continent • (today’s high latitude continents and mountains could contribute to cooling) • “The fact that natural factors caused climate changes in the past does not mean that the current climate change is natural. By analogy, the fact that forest fires have long been caused naturally by lightning strikes does not mean that fires cannot also be caused by a careless camper. “

23. So what does our past climate look like?