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Earth history 2
1) Changes in the atmosphere, such as variations in greenhouse gases, solar radiation levels, volcanic activity, and ice sheet size can impact climate by altering the Earth's energy balance. 2) Scientific evidence shows that small variations in the Earth's orbit and axis (known as the Milankovitch cycles) have paced climate changes over hundreds of thousands of years by changing the distribution of solar energy received in different latitudes and seasons. 3) Positive feedback loops involving greenhouse gases, ice sheets, and temperature amplified the effects of the Milankovitch cycles in the past, driving the Earth into ice ages. However, human emissions are now the dominant factor changing climate through increased greenhouse gases.
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Earth history 2
- 1. EARTH HISTORY 2 Changesin Atmosphere ppt. by Robin D. Seamon
- 2. CLIMATE VARIABLES VIDEO: IanStewart ‘Atmosphere’ (50 min)
- 3. It’s all connected!Changes in one affects the other:
- 5. CLIMATE CHANGES Atmosphere: gaslayer 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
- 6. 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
- 7. • Life affectsgas 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/
- 8. 2. Variations insolar 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 VIDEO: CC 4- Climate change, chaos & little Ice Age (10 min)
- 9. 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
- 10. EXAMPLES: • Mountains vs.plains • Large continent vs. several smaller ones • Connection of two continents block off ocean currents- Isthmus of Panama
- 11. • IN PAST-tectonic movement caused big storage of Carbon- fossil fuels TODAY: Coal mines Carboniferous Era VIDEO: Formation of Fossil Fuels (2:30)
- 12. 4. Volcanic eruptions& LIPs • spew gases into the atmosphere- changes chemistry (LIFE) http://www.bbc.co.uk/news/world-asia-29399306 Mt Ontake 9/27/2014
- 13. • LIP- largeigneous provinces Places where igneous large rock beds indicate a flow of lava from cracks in the crust
- 14. • Can blockout 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)
- 15. MODERN EXAMPLES: 1815 Mt.Tambora: Year without a Summer 1991: Mt. Pinatubo: global temp down 0.9˚F for 3 yrs
- 16. 5. Cryosphere: icelayer http://www.toppforskningsinitiativet.org/en/programmer-1/program-2 http://rramu0153.wordpress.com/
- 17. • During iceages, sea levels are lower • water/run-off is trapped in ice • not in water cycle = DRIER VIDEO NASA Sea Ice 2008 (3:00)
- 18. • Albedo: amountof ice affects temperature: • more ice: more sunlight is reflected back off Earth • less ice: Earth absorbs more solar Energy • Carbon sink: ice keeps dead organisms from decomposing (more carbon) is absorbed than released http://www.earthgauge.net/2011/system-dynamics
- 19. 6. Milankovitch Cyclevariation in intensity of sunlight due to slight variation in Earth’s orbit • Pace setter for cycles of warming & cooling
- 20. http://www.bgs.ac.uk/discoveringGeology/climateChange/ge neral/causes.html?src=topNav http://www.southwestclimatechan ge.org/figures/milankovitch Orbital shape: (eccentricity) Earth’s orbitchanges from it’s elliptical shape; 100,000 yrs Orbital axis wobble: Changes in tilt causes strength of seasons 20,000- 40,000 yrs VIDEO: Orbital Forcing (1 min)
- 21. 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
- 22. • Natural Causes •Cold oceans absorb CO • Warm oceans release CO • CH (methane) from decay 2 2 4
- 23. • 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)
- 24. http://en.wikipedia.org/wiki/Climate_change#mediaviewer/Fil e:NSFmonsoonsandclimatesince200AD.jpg Human civilizations affectedby climate changes: VIDEO 2: 300 yrs of fossil fuels in 300 sec (5:30) VIDEO 1: Climate 101 with Bill Nye (4:30)
- 25. CO2 carbon dioxide CH4methane H2O water C O 1 2 C H 1 4 H O 2 1 1 carbon atom, 2 oxygen atoms 1 carbon atom, 4 hydrogen atoms 2 hydrogen atoms, 1 oxygen atom
- 26.
- 27. How do scientistsmeasure atmosphere from earlier in Earth’s history? Radiometric Dating in: Rocks & sediment • Sea floor cores composition & past temperature • Loess composition & past temperature
- 28. Ice core data •Layer size, pattern, & • Composition VIDEO : Drilling back to the Future (6:20)
- 29. Ancient Fossils foraminifera inancient sea beds
- 30. Glaciers – moraine sediments Evidenceleft of past sea levels • On shore • In ancient coral beds
- 31.
- 32. Pleistoscene Epoch: mostrecent Epoch in Earth’s history- glacier cycles • Before that: long eras of warm climate
- 33. Late 19th Century: •Patterns were seen, but tools not there to date stuff • Palynology: study of pollen • Each species distinctive & durable • Show patterns of where plants lived in the past • (hot-cold range) SO SCIENTISTS STUDIED:
- 34. • Saw fossilhoards 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???
- 35. • 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
- 36. • 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
- 37. 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
- 38. • Said patternsmatched Ice Age cycle predicted by Milankovitch • Didn’t match the Big 4 glaciations • Needed to dig farther for pattern?
- 39. • 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
- 40. • 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
- 41. 1. Sea levelchanges 2. Temperature of deep sea cores SO: Orbital variations verified in: ??? How could something as small as angle of sunlight cause ice Ages???
- 42. • Global Cooling:1970’s Emiliani predicts start of a new Ice Age soon • warned that greenhouse warming caused by humans could overwhelm orbital shifts • Magnetic Reversals: new dating technique verified age of rocks & core samples being studied
- 43. 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)
- 44. • Ratio ofoxygen in ice can measure temperature inside cloud it was formed • (warmer air= heavier isotope of O)
- 45. • 1950’s USCamp Century created in Greenland (Cold War) • 1966 -1 mile down • Ice core showed last 100,000 yrs THEORIES CONFIRMED 1971-1980: VIDEO: Camp Century Truthloader (4:30)
- 46. • 1968 USByrd Station created in W. Antarctica • Confirmed Ice Age happened at same time in N & S (GLOBAL GLACIATION)
- 47. • Showed samesaw-tooth curve pattern seen in deep sea cores: Brief warmth Longer cold http://www.skepticalscience.com/trend_and_variation.html
- 48. Nicholas Shackleton 1973used magnetic reversal dates & deep core samples • Confirmed sea levels coincides with Ice Sheets • matched Milankovitch cycles • deep sea drilling • loess SO: 100,000 yr cycle verified in:
- 49. • Earth’s climatesystem has evolved in the past so change is possible • Feedback mechanisms: natural responses that add to the system ??? How was Milankovitch Cycle a pace maker to trigger Ice Ages??? ??? What were the feedback mechanisms that amplified the Mil. Cycle???
- 50. • 1980’s scientistsnoticed CO levels went up or down with the temperature in the past • Russiann Vostok Station (1957 +) cores • CO & CH during Ice Age • CO & CH in warm periods ??? GAS KEY ??? 2 2 4 42
- 51. • 1980’s globalwarming becomes a political issue ??? Could swing in greenhouse GASES amplify orbital shifts ???
- 52. • Greenhouse warming& other human influences strong enough to change the natural trend • Could launch Earth into a wholly new climate trend (new pattern) • 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 FACTS: Scientists Warn:
- 54.
- 55. Changes in Feedback? •In past glaciations it appears that: • Sunlight • Temperature • CO & CH from oceans Making a warming loop until Mil. Cycle turns the cycle towards cooling 2 4 CO & CH increase 2 4Ice melts- albedo decreases Temperature increases
- 56. Temperature CO & CH24 CO & CH2 4 Temperature FASTER SLOWER
- 57. THEN orbital shift: •Sunlight • Temperature • CO & CH from oceans Making a cooling loop until Mil. Cycle turns the cycle towards warming 2 4 CO & CH decrease 2 4Ice forms- albedo increases Temperature decreases decreased
- 58. 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 temperature first 2
- 59. NEW: • Gas levelsrising faster than anything seen for millions of years & natural feedbacks are kicking in • Drying forests • Warmer seas • Methane from Arctic melt
- 60. CONCLUSION • Geological recordverifies 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)
- 61. *********************** VIDEO: Ian Stewart:Cryosphere (50 min)
- 62.