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Earth History 2: Changes in Atmosphere

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Changes of atmosphere in Earth's history

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Earth History 2: Changes in Atmosphere

  1. 1. EARTH HISTORY 2 Changes in Atmosphere ppt. by Robin D. Seamon
  2. 2. CLIMATE VARIABLES
  3. 3. It’s all connected! Changes in one affects the other:
  4. 4. CLIMATE CHANGES Atmosphere: gas layer of the earth; it’s where weather happens Climate: weather patterns shown over time ** if the atmosphere changes so does the climate** QUESTION: What creates change in climate? ANSWER: Changes in atmosphere
  5. 5. 1. Biotic processes (life) ** • Respiration: breathing in/out O and CO • Transpiration: release of H 0 and CO • Waste products • Recycling of gases after death 2 2 2 2
  6. 6. • Life affects gas cycles: • Carbon Cycle • Water Cycle • Cloud formation • Weathering EXAMPLE: 2.4 bya The Great Oxidation Event (put oxygen into atmosphere) http://guardianlv.com/2014/02/australian-crystal-found-is-4-4-billion-years-old/
  7. 7. 2. Variations in solar radiation • amount affects photosynthesis, precipitation, wind patterns, temperature (AFFECTS LIFE) • Sun has cycles of solar storms (flares) & sun spots which could affect earth & it’s life EXAMPLE: 1550-1850 Little Ice Age Thames River: HENDRICK AVERCAMP'S LITTLE ICE AGE
  8. 8. 3. Plate tectonics • shape of the continents determine ocean & wind currents • How heat is transferred • How much moisture http://www.bgs.ac.uk/discoveringGeology/climateChange/general/causes.html?src=topNav
  9. 9. EXAMPLES: • Mountains vs. plains • Large continent vs. several smaller ones • Connection of two continents block off ocean currents- Isthmus of Panama
  10. 10. • IN PAST- tectonic movement caused big storage of Carbon- fossil fuels Carboniferous Era TODAY: Coal mines VIDEO: Formation of Fossil Fuels (2:30)
  11. 11. 4. Volcanic eruptions & LIPs • spew gases into the atmosphere-changes chemistry (LIFE) Mt Ontake 9/27/2014 http://www.bbc.co.uk/news/world-asia-29399306
  12. 12. • LIP- large igneous provinces Places where igneous large rock beds indicate a flow of lava from cracks in the crust
  13. 13. • Can block out sunlight, preventing photosynthesis (LIFE) • Meteor induced http://news.nationalgeographic.com/news/2013/13/130212--chicxulub-asteroid-dinosaurs-volcano-mass-extinction-environment- science/ VIDEO: Large Igneous Province formation (2:00)
  14. 14. MODERN EXAMPLES: 1815 Mt. Tambora: Year without a Summer 1991: Mt. Pinatubo: global temp down 0.9˚F for 3 yrs
  15. 15. 5. Cryosphere: ice layer http://www.toppforskningsinitiativet.org/en/programmer-1/program-2 http://rramu0153.wordpress.com/
  16. 16. • During ice ages, sea levels are lower • water/run-off is trapped in ice • not in water cycle = DRIER VIDEO NASA Sea Ice 2008 (3:00)
  17. 17. • Albedo: amount of ice affects temperature: • more ice: more sunlight is reflected back off Earth • less ice: Earth absorbs more solar Energy http://www.earthgauge.net/2011/system-dynamics • Carbon sink: ice keeps dead organisms from decomposing (more carbon) is absorbed than released
  18. 18. 6. Milankovitch Cycle variation in intensity of sunlight due to slight variation in Earth’s orbit • Pace setter for cycles of warming & cooling
  19. 19. http://www.bgs.ac.uk/discoveringGeology/climateChange/ge neral/causes.html?src=topNav Orbital shape: (eccentricity) Earth’s orbit changes from it’s elliptical shape; 100,000 yrs http://www.southwestclimatechan ge.org/figures/milankovitch Orbital axis wobble: Changes in tilt causes strength of seasons 20,000- 40,000 yrs VIDEO: Orbital Forcing (1 min)
  20. 20. 7. Greenhouse Gases • More greenhouse gases = thicker blanket, holding in solar radiation (warmer) • Fewer greenhouse gases = thinner blanket, trapping less solar radiation= (cooler) http://www.ib.bioninja.com.au/standard-level/topic-5-ecology-and-evoluti/ 52-the-greenhouse-effect.html
  21. 21. • Natural Causes • Cold oceans absorb CO 2 • Warm oceans release CO 2 • CH (methane) from decay 4
  22. 22. • Human contributions • Release of carbon into the air through burning of fossil fuels & cement manufacture increases the greenhouse layer • Aerosol increase (tiny particles in atmosphere)
  23. 23. Human civilizations affected by climate changes: http://en.wikipedia.org/wiki/Climate_change#mediaviewer/Fil e:NSFmonsoonsandclimatesince200AD.jpg VIDEO 1: Climate 101 with Bill Nye (4:30) VIDEO 2: 300 yrs of fossil fuels in 300 sec (5:30)
  24. 24. PALEOCLIMATOLOGY -study of ancient climate
  25. 25. How do scientists measure atmosphere from earlier in Earth’s history? Radiometric Dating in: Rocks & sediment • Sea floor cores composition & past temperature • Loess composition & past temperature
  26. 26. Ice core data • Layer size, pattern, & • Composition VIDEO : Drilling back to the Future (6:20)
  27. 27. Ancient Fossils foraminifera in ancient sea beds
  28. 28. Glaciers – moraine sediments Evidence left of past sea levels • On shore • In ancient coral beds
  29. 29. HISTORY OF PALEOCLIMATOLOGY
  30. 30. Pleistoscene Epoch: most recent Epoch in Earth’s history- glacier cycles • Before that: long eras of warm climate
  31. 31. Late 19th Century: • Patterns were seen, but tools not there to date stuff SO SCIENTISTS STUDIED: • Palynology: study of pollen • Each species distinctive & durable • Show patterns of where plants lived in the past • (hot-cold range)
  32. 32. • Saw fossil hoards of nuts showed hazel trees farther N 5,000 yrs ago • Sea level change: • (ice locks up ice from water cycle, lowering ocean levels during Ice Ages) • Coastal crust showed sea level changes with a long time between Ice Ages ??? How were Ice Ages triggered???
  33. 33. • Traditional View: Earth only had 4 big glaciations, based on surface strata • Moraines: rocks & sediments carried & deposited by a glacier at its farthest edges http://www.mediahex.com/Moraine
  34. 34. • Astronomy 1920’s & 1930’s • Milutin Milankovitch’s Theory (Serbian) Saw patterns in Earth’s orbit that he thought coincided with Ice Ages in Earth’s past • 20,000 yr cycle (inclination) • 100,000 yr cycle (eccentricity) • Conflicted with traditional view so most scientists dismissed
  35. 35. Reliable Dates & Temperatures 1955-1971 • Absolute dating- new tool: radiometric dating • Cesare Emiliani (Italian) 1955 recorded temp variations from the amount of oxygen in ancient sea shells
  36. 36. • Said patterns matched Ice Age cycle predicted by Milankovitch • Didn’t match the Big 4 glaciations • Needed to dig farther for pattern?
  37. 37. • Wallace Broecker (US) 1968 studied ancient coral reef beds • Different elevations showed that the sea levels went up and down with Ice Sheets • Used radiometric dating Uranium • Matched Milankovitch cycles
  38. 38. • George Kukla (Czech Republic) 1977 studied loess to confirm existence of dozens of Ice Ages • Loess wind-blown dust accumulations that were found in clay quarry on land
  39. 39. SO: Orbital variations verified in: 1. Sea level changes 2. Temperature of deep sea cores ??? How could something as small as angle of sunlight cause ice Ages???
  40. 40. • Global Cooling: 1970’s Emiliani predicts start of a new Ice Age soon • He warned that greenhouse warming caused by humans could overwhelm orbital shifts • Magnetic Reversals: new dating technique verified age of rocks & core samples being studied
  41. 41. Ice Core Samples • Samples of ancient air! • Show past atmosphere composition • Show aerosols (small particles in air) • Scientists can count layers yearly • Can be checked with major known eruptions (like Pompeii in 79CE) VIDEO 1: Drilling for Ice (3:20)
  42. 42. • Ratio of oxygen in ice can measure temperature inside cloud it was formed • (warmer air= heavier isotope of O)
  43. 43. THEORIES CONFIRMED 1971-1980: • 1950’s US Camp Century created in Greenland (Cold War) • 1966 -1 mile down • Ice core showed last 100,000 yrs VIDEO: Camp Century Truthloader (4:30)
  44. 44. • 1968 US Byrd Station created in W. Antarctica • Confirmed Ice Age happened at same time in N & S (GLOBAL GLACIATION)
  45. 45. • Showed same saw-tooth curve pattern seen in deep sea cores: Brief warmth Longer cold http://www.skepticalscience.com/trend_and_variation.html
  46. 46. Nicholas Shackleton 1973 used magnetic reversal dates & deep core samples • Confirmed sea levels coincides with Ice Sheets • matched Milankovitch cycles SO: 100,000 yr cycle verified in: • deep sea drilling • loess
  47. 47. ??? How was Milankovitch Cycle a pace maker to trigger Ice Ages??? • Earth’s climate system has evolved in the past so change is possible • Feedback mechanisms: natural responses that add to the system ??? What were the feedback mechanisms that amplified the Mil. Cycle???
  48. 48. ??? GAS KEY ??? • 1980’s scientists noticed CO levels went up or 2 down with the temperature in the past • Russiann Vostok Station (1957 +) cores • CO & CH during Ice Age • CO & CH in warm periods 2 4 2 4
  49. 49. ??? Could swing in greenhouse GASES amplify orbital shifts ??? • 1980’s global warming becomes a political issue
  50. 50. Scientists Warn: • Greenhouse warming & other human influences strong enough to change the natural trend • Could launch Earth into a wholly new climate trend (new pattern) FACTS: • Climate Sensitivity CO levels in past 750,000 yrs at 180-280 parts per million • In 2012: levels were at 400 ppm and rising (methane too) 2
  51. 51. http://www.science20.com/virtual_worlds/blog/is_global_warming_real ly_a_recovery_from_regional_cooling-121820 SEA ICE http://www.forbes.com/sites/alexknapp/2013/09/10/the-daily-mail-is-wrong-the-earth- keeps-warming/ SEA LEVEL
  52. 52. Changes in Feedback? • In past glaciations it appears that: • Sunlight • Temperature • CO & CH from oceans 2 4 Making a warming loop until Mil. Cycle turns the cycle towards cooling CO & CH increase Temperature increases Ice melts- 2 4 albedo decreases
  53. 53. Temperature CO & CH 2 4 Temperature CO & CH 2 4 FASTER SLOWER
  54. 54. THEN orbital shift: • Sunlight • Temperature • CO & CH from oceans 2 4 Making a cooling loop until Mil. Cycle turns the cycle towards warming CO & CH decrease decreased Temperature decreases Ice forms- 2 4 albedo increases
  55. 55. IN THE PAST: • Temp increased b/c of sun angle shift • Sun angle shift started the loop, increasing the greenhouse gases & warmth NEW: • Orbital shift isn’t triggering the warming trend • extra greenhouse gases are starting the process • NOW- CO levels are increasing the 2 temperature first
  56. 56. NEW: • Gas levels rising faster than anything seen for millions of years & natural feedbacks are kicking in • Drying forests • Warmer seas • Methane from Arctic melt
  57. 57. CONCLUSION • Geological record verifies with independent methods & data the process computer models are predicting: • Disruption of climate from its recent patterns ??? What will the changes be??? This is where the ARGUMENTS BEGIN… VIDEO: Crash Course-Climate Change (10:00)
  58. 58. RESOURCES http://www.aip.org/history/climate/cycles.htm http://en.wikipedia.org/wiki/Climate_change http://www.bgs.ac.uk/discoveringGeology/climateC hange/general/causes.html?src=topNav

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