Earth History: Changes in Earth's Atmosphere

1. EARTH HISTORY 2
Changes in Atmosphere
ppt. by Robin D. Seamon

2. CLIMATE VARIABLES
VIDEO: Ian Stewart ‘Atmosphere’ (50 min)

3. It’s all connected! Changes in one affects the other:

5. 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

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 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/

8. 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 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- large igneous provinces
Places where igneous large rock beds indicate a
flow of lava from cracks in the crust

14. • 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)

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: ice layer
http://www.toppforskningsinitiativet.org/en/programmer-1/program-2
http://rramu0153.wordpress.com/

17. • 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)

18. • Albedo: amount of 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 Cycle variation 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 orbit changes
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 affected by
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
CH4 methane
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. PALEOCLIMATOLOGY
-study of ancient climate

27. 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

28. Ice core data
• Layer size, pattern, &
• Composition
VIDEO : Drilling back to the Future (6:20)

29. Ancient Fossils
foraminifera in ancient
sea beds

30. Glaciers –
moraine sediments
Evidence left of past sea levels
• On shore
• In ancient
coral beds

31. HISTORY OF
PALEOCLIMATOLOGY

32. Pleistoscene Epoch: most recent 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 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???

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 patterns matched 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 level changes
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 of oxygen in ice can measure temperature
inside cloud it was formed
• (warmer air= heavier isotope of O)

45. • 1950’s US Camp 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 US Byrd Station created in W. Antarctica
• Confirmed Ice Age happened at same time in
N & S (GLOBAL GLACIATION)

47. • Showed same saw-tooth curve pattern seen in
deep sea cores:
Brief warmth
Longer cold
http://www.skepticalscience.com/trend_and_variation.html

48. Nicholas Shackleton 1973 used 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 climate system 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 scientists noticed 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 global warming 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. http://www.science20.com/virtual_worlds/blog/is_global_warming_real
ly_a_recovery_from_regional_cooling-121820
http://www.forbes.com/sites/alexknapp/2013/09/10/the-daily-mail-is-wrong-the-
earth-keeps-warming/
SEA ICE
SEA LEVEL

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 & CH2 4
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 levels rising faster than anything seen for
millions of years & natural feedbacks are
kicking in
• Drying forests
• Warmer seas
• Methane from Arctic melt

60. 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)

61. ***********************
VIDEO: Ian Stewart: Cryosphere (50 min)

62. 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