EARTH HISTORY 2Changes in Atmosphere

ppt. by Robin D. Seamon

CLIMATE VARIABLES

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

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

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

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• 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/

2. Variations in solar radiation• amount affects photosynthesis, precipitation,

wind patterns, temperature (AFFECTS LIFE)• Sun has cycles of solar

storms (flares) & sun spots which couldaffect earth & it’s life

EXAMPLE: 1550-1850 Little Ice Age

Thames River: HENDRICK AVERCAMP'S LITTLE ICE AGE

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

EXAMPLES:• Mountains vs. plains• Large continent vs. several smaller ones• Connection of two continents block off

ocean currents- Isthmus of Panama

• IN PAST- tectonic movement caused big storage of Carbon- fossil fuels

TODAY: Coal mines

Carboniferous Era

4. Volcanic eruptions & LIPs• spew gases into the atmosphere-

changes chemistry (LIFE)

http://www.bbc.co.uk/news/world-asia-29399306

Mt Ontake9/27/2014

• LIP- large igneous provincesPlaces where igneous large rock beds indicate a flow of lava from cracks in the crust

• 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/

MODERN EXAMPLES:1815 Mt. Tambora: Year without a Summer1991: Mt. Pinatubo: global temp down 0.9˚F for 3 yrs

5. Cryosphere: ice layer

http://www.toppforskningsinitiativet.org/en/programmer-1/program-2

http://rramu0153.wordpress.com/

• During ice ages, sea levels are lower • water/run-off is trapped in ice • not in water cycle = DRIER

• 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

6. Milankovitch Cycle variation in intensity of sunlight due to slight variation in Earth’s orbit

• Pace setter for cycles of warming & cooling

http://www.bgs.ac.uk/discoveringGeology/climateChange/general/causes.html?src=topNav

http://www.southwestclimatechange.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

seasons20,000- 40,000 yrs

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

• Natural Causes• Warm oceans absorb CO • Cold oceans release CO• CH (methane) from decay

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• 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)

http://en.wikipedia.org/wiki/Climate_change#mediaviewer/File:NSFmonsoonsandclimatesince200AD.jpg

Human civilizations affected by climate changes:

PALEOCLIMATOLOGY-study of ancient climate

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

Ice core data• Layer size, pattern, & • Composition

Ancient Fossils

foraminifera in ancient sea beds

Glaciers –moraine sediments

Evidence left of past sea levels• On shore• In ancient

coral beds

HISTORY OF PALEOCLIMATOLOGY

Pleistoscene Epoch: most recent Epoch in Earth’s history- glacier cycles• Before that: long eras of warm climate

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:

• 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???

• 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

• 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

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

• Said patterns matched Ice Age cycle predicted by Milankovitch

• Didn’t match the Big 4 glaciations• Needed to dig farther for pattern?

• 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

• 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

1. Sea level changes2. Temperature of deep sea cores

SO: Orbital variations verified in:

??? How could something as small as angle of sunlight cause ice Ages???

• 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

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)

• Ratio of oxygen in ice can measure temperature inside cloud it was formed

• (warmer air= heavier isotope of O)

• 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:

• 1968 US Byrd Station created in W. Antarctica• Confirmed Ice Age happened at same time in

N & S (GLOBAL GLACIATION)

• Showed same saw-tooth curve pattern seen in deep sea cores:

Brief warmth

Longer cold

http://www.skepticalscience.com/trend_and_variation.html

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:

• 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???

• 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 ???

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• 1980’s global warming becomes a political issue

??? Could swing in greenhouse GASES amplify orbital shifts ???

• 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)

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FACTS:

Scientists Warn:

http://www.science20.com/virtual_worlds/blog/is_global_warming_really_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

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 & CHincrease

2 4Ice melts-albedo

decreases

Temperature increases

Temperature

CO & CH 2 4CO & CH 2 4

Temperature

FAST

ER

SLO

WER

THEN orbital shift:• Sunlight • Temperature • CO & CH from oceans

Making a cooling loop until Mil. Cycle turns

the cycle towards warming

2 4

CO & CHdecrease

2 4Ice forms-albedo

increases

Temperature decreases

decreased

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 first2

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

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…

RESOURCEShttp://www.aip.org/history/climate/cycles.htm

http://en.wikipedia.org/wiki/Climate_change

http://www.bgs.ac.uk/discoveringGeology/climateChange/general/causes.html?src=topNav