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exosphere -> thermosphere -> mesosphere -> stratosphere -> troposphere (
gas reflectors
aerosols (sulfates, soot, organic carbon, dust) in stratosphere, volcanic ash,
gas absorbers
thermohaline circulation
conveyor belt

1Dr Heumann's Lectures

1.1Thermohaline circulation

1.1.1Greenhouse gases

1.1.2El Nino, La Nina, and Arctic Oscillation

  • 5 yr cycles
  • Reduced trade wind, warm water in pacific- El Nino
  • Opposite of El Nino La Nina
  • Arctic Oscillation - dominant pattern of non-seasonal sea-level pressure variations north of 20N

1.1.3Causes for short + long term climate change in last 200 yrs
  • 1) tectonic, volcanos (short term)
  • 2) earth's orbit
  • 3) sun strength (long term)/11 year sunspot activity (short term)
  • 4) greenhouse gases (long term) - water, co2,
  • 5) land use change (long term)
  • 6) tropospheric aerosols (long term)
  • 7) greenhouse gases (long term)
  • 1) del atmosphere
  • 2) del ice
  • 3) del vegetation
  • 4) del ocean
  • 5) del land
  • 6) thermohaline circulation (long term)
  • 7) el nino (short term) term

1.1.4Solar radiation effects and sunspot activity

  • greenhouse affect: longwave heat radiation, not shortwave solar radiation

1.1.5Energy distribution of Earth's surface

  • albedo: 31% (percent light reflected out)

1.1.6Negative Feedback

  • CO2-> photosynthesis

1.1.7Positive feedback

  • respiration, temp, co2
  • soil water, evapotranspiration, precipitation
  • albedo, temp, snowcover

1.2The Players

1.2.1Louis Aggasiz
  • Spokesperson he expanded on

From 1787-1832...
- the Swiss mountaineers
- Kuhn, Swiss Minister, erratic boulders sign of glaciation
- Hutton, Scottish Father of Modern Geology, erratic boulders sign of glaciation
- Parraudin, Swiss mountaineer/hunger, striations are caused by glaciers, clearly shown by receding glaciation aorund him
- Venetz, Swiss Engineer, characterized/systemized glaciar movements, deduced glaciers far more extensive
- Esmark, Norway Prof, deduced glaciers far more extensive
- Charpentier, German/Swiss geologist, categorized evidence (convinced by venetz)
- Bernhardi, German proff, paper: ice cap spread over europe won him over
  • Charpentier showed him in person

1.2.2Reverend Professor William Buckland
  • One of most respected geologists at the time
  • believed that the "objective of geology was to confirm the evidence of natural religion and to show that the facts developed by it are consistent with the accounts of creation and deluge recorded by the mosaic writings of the bible"
  • important to win over won him over
  • one trip to the mountains with Agassiz and a couple of years and then a second trip

1.2.3Charles Lyell
  • founder of ice raft theory to explain both erratic boulders and ice-rafted boulders won him over
  • Buckland convinced him by showing him some moraines
  • explained things he couldn't explain before

1.3Early Evidence

1.3.1Ice-Rafted Boulders Explanation
  • boulders were frozen in ice rafts in high lakes and drifted around
  • this truly happens and no contradiction lies here
  • since ice rafted boulders are not smooth, there is no evidence that they were carried by glaciers

1.3.2Erratic Boulders

Erratic Boulders
Giant boulders resting in a place far from their bedrock orign Explanation
  • boulders were frozen in icebergs and carried away Contradiction
  • doesn't explain rocks at high altitudes Explanation
  • glaciers smoothed them out

1.3.3Striated rocks Explanation
  • glaciers scratched them as they moved over them

1.3.4polished rocks

  • rocks seen when glaciers recently melted or rocks recently uncovered
  • very smooth, not caused by weathering (weathering erodes) explanation
  • ice and smaller debris polished the rocks


  • makeup of the till doesn't match the bedrock: evidence of the extent of glaciers
    terminal moraine
    debris that is dumped by the glacier like a conveyor belt
    lateral moraine
    moraine is on the edges of glaciar
    carried along by the glacier and melted at the end (in lateral moraines)
    recessional moraine
    periodic perpendicular ridges - caused by temporary halts
    medial moraine
    in center of valley where two glaciers meet



  • Lyell said techtonic activity caused it (higher altitude, lower temps)
  • James Geike said this was impossible, too slow


  • too minimal

1.4.3co2 levels

  • no one knew co2 levels would've dropped

1.4.4volcanic eruptions

  • too temporary

1.4.5astronomical theory

  • see below

1.4.6astronomical theory
12 hrs daylight, 12 hrs darkness everywhere (fall and spring)
summer solstice
longest day in the northern hemisphere
100k-400k yrs
20-23 degree tilt, 41k yrs
timing of seasons, shifts the solstices/equinoxes around the orbit every 21k yrs
lines of latitude that mark the tilt of the earth (i.e. change with obliquity)
point at which earth is closest to sun
point at which earth is furthest from sun
  • first to propose astronomical theory
  • 'precession of the equinox' - whichever hemisphere had a longer winter would have an ice age
  • based on differences in number of hours of daylight in summer vs winter (i.e. long winters cause it)
  • had the eccentricity as a constant. on
  • Jean le Rond D'Alembert: showed that equinoxes shift (winter in northern hemisphere is close to sun, but in 11k yrs, winter will be on the opposite side of the ellipse) sayers
  • Alexander von Humboldt: avg temp is controlled by radiation, not by hrs of sunlight, so temp is still balanced out per year (radiation balances!) Croll
  • precession AND ecentricty caused ice ages
  • thought that an extra cold winter could start an ice age
  • positive feedback
  • believed in hemispherical ice ages (if earth is far from sun, high eccentricity, and northern hemisphere is pointing away, precession, then ice age during the aphelion)
  • believed that if currents changed, moving war water/moisture/air away from north towards south, then this could amplify ice age
  • Geikie Bros: supported it cuz they had evidence that multiple ice ages occurred, as predicted by Lyell upon
  • Adhemar - read his book in a library 25 yrs later
  • Le Verrier - published on eccentricity sayers
  • Charles Lyell - Croll said 80-150k year cycles, but Lyell found evidence at Niagra falls showing 30k
  • Newton Winchell - 10k-15k evidence (mississippi)
  • precession, eccentricty, and axial tilt
  • cooler summer in high latitudes responsible (less ice melting)
  • goal 1: geometry of orbit and how it changed over time
  • goal 2: calculate how much solar radiation strikes the surface (each planet, each season, each latitude)
  • goal 3: mathematical models of earth's past climates (650k yrs back at 55, 60, 65 lines)
  • goal 4: feedback: how much ice sheets would respond to change in solar radiation
  • wladimir Koppen: climate zones: "reduction of heat during summer was decisive factor in causing glaciation", matched euro erosion with mil's cycles
  • Alfred Wegener: Continental drift, cited Mil in "Climates of Geological Past"
  • Albert Penck and Eduard Bruckner: Mil's graph matched well with these guys glacier history maps work on
  • Adhmar, Croll
  • Ludwig Pilgrim: did most of the calculations 7 yrs earlier sayers
  • Ingo Shafer - fossils in alpine terrace dated to contradict Mil's ice age - impossible for mollusks in an ice age
  • Meteorologists - theory failed to incorporate role of atmosphere and ocean
  • Richard Flint and Meyer Rubin - radiocarbon dating: ice sheet reached maximum extent 18k yrs ago
  • Discovery of 25k yr old peat layer in illinois shattered Milakovitch thoery

1.5revival of Milaknovitch

1.5.1Sea Terraces

  • New Guinea terraces (top to bottom: 125k, 105k, and 82k) lined well with Mil's warm periods at 45 deg North (not at 65 deg North, where Mil had 40k year cycle, didn't predict 105k)
  • Mil's theory should place more emphasis on precession
  • players: Matthews, Brown University, New Guinea; Broecker: fossil reefs (florida keys), found 80k and 120k, matches Matthews' New Guinea data to Mil

1.5.2Magnetic Timeline

  • Brickards
  • Players: Bernard Brunhes (Brickyards) and Matuyama
  • Now possible to date any core that had a magnetic signal
  • Potassium-Argon dating

1.5.3Loess and George Kukla

  • 5 soil-Loess cycle matching w/5 magnetic reversals: 100k yrs,
  • Loess: from outwash streams of glaciers
  • Kukla concluded: "cooling phase of climatic cycle lasted much longer than the warming phase. transitions from dusty polar desert phases to deciduous forest pahses were soabrupt that they appeared in the quarry walls as distinct lines"
  • proved Penck+Bruckner, and Koppen+Wegner wrong
  • "Mesolella at Brown and Kuukla in Czech found ways of modifying Milankovitch theory to account for 100k cycle. Both pointed out that the dominant cycle in the eccentricty curves (close to 100k) was a good match for climatic pulse
  • intensity of radiation during a season: precession
  • amplitude of radiation: eccentricity
  • Mesolella: summer was critical season
  • Kukla: Winter radiation critical

1.5.4Climate Project: Hayes and Imbrie

  • Two objectives:
    • 1) Map earth's surface over last ice age
    • 2) Measure Pleistocene Oscillations
      period of repeated glaciations (as many as 11 large ones)
      after Pleistocene, -11,700 yrs to today - no glaciation
      Pleistocene Interglacial
      any period where oak and other deciduous trees are widespread in europe
      Start of Pleistocene
      date at which oldest cold water fossil found (1.8 million years ago)
      Age of earth
      4.6 billion years
      Age of oceans
      3.8 billion years
      Age of dinosaurs
      65 million years ago
  • Results - - 1) climate oscillations have 4 frequency components: 41k axial tilt, 23k and 19k precession, 100k eccentricity
    • Imbrie: ice sheets lag 8k years behind axial tilt
    • ice sheets also lag behind 23k precession cycle


1.6.1Laurentide ice sheet (North America) features
Terminal Moraine
pile of till that marks the furthest extent of the ice sheet or glaciar
Kettle ponds
lakes formed by melted icebergs (carried by outwash streams)
long 'railway like' deposits left by streams flowing under glaciers
almond shape formed by receding glacier glacier features
ridge between two valleys (caused by, respectively, two receding glaciers)
valley carved out into a bowl (think circus -> amphitheater)
hanging valley
waterfall: light glacier runs into heavy glacier
glacial lakes
form in cirques or behind/between recessional moraines definitions/ideas
global rise in sea level (due to polar ice caps) - think 'ecstatic about flordia drowning'
rebound of lithosphere (land) in response to weight of ice sheets removed
lake champlain formation
; result of isostasy - used to be salt water
cordilleran ice sheet
north america, eastern side connected with laurentide ice sheet.
lake missoula
formed behind ice dam, emptied suddenly, connected to cordilleran ice sheet
glacier ice dam flooding
may be result of many great floods recorded in history

1.7human migration

area untouched by glaciers - place where plants/animals live
south america migration
last continent, 10k yrs ago
hawai'i migration
300 AD
Fiji migration
1500 BC
New Zealand
1000 AD
Canada/US Migration
12k yrs ago

Asia Migration
:30k yrs ago

1.8Little Ice Age


  • 1350-1850
  • 2-3 degree C change
  • high weather volatility

1.8.2Warm period

  • 900-1300, 7 degrees warmer than today
  • Optimism, cereal grains, <3 God
  • Viking migration, Newfoundland migration, Swedes to russia

1.8.3Causes of Lil Ice Age

  • Less radiation (only 0.5%)
  • Sulfur deposits (volcanos)
  • Thermohaline circulation stopping due to influx of fresh water (normally surface currents from equator to the north)
    Maunder Minimum
    Temp decrease in middle of lil ice age: due to decreased sunspots
  • 1645-1715

1.8.4Beginnings of Lil Ice Age

  • 1315-1320: Extreme rain
  • 1.5 mil died in famine
  • cereal died

1.8.5Greenland + Vikings + Newfoundland

  • settled during warm period
  • food: pre ice age: 20% marine, 80% land. Ice age: 20% land, 80% marine (land animals died + erosion + fragile land)
  • failed to adapt to inuits (who had excellent fishing techniques)
  • Massive deforestation
  • Also made it over to the tip of newfoundland (seasonal settlement, animals kept inside houses)
  • Inuits migrated from Northern Canada to Greenland
    = No cargo ships from Norway
  • Vikings sucessful cuz 1) great ships and 2) predictable climate
  • Leif sailed westward to northern newfoundland


  • settled in 864 - not during warm period
  • Eric the Red kicked out of iceland, moved to greenland


  • experienced cool period during the warm period
  • Southwest US
  • experienced drought, crop failures, overpopulation


  • Frost fair on River Thames (1607-1814) - London
  • Washington cross delaware
  • Hudson River frozen (Manhattan $\rightarrow$ Long Island


  • Cereal $\rightarrow$ potatoes (UK)
  • Farming economy (veggies for meat)
  • France + Pope Innocent didn't like potatoes
  • Unable to burn potato farms in war
  • Irish potato monoculture $\rightarrow$ potato famine
  • More resistant (cold, wet, dry) and more diverse


  • Varnish, hard wood (maunder minimum), geometry


  • production of decreased in northern europe $\rightarrow$ northern europeans migrated to america
  • vines 300 south to where they were in warm period
  • American Immigrants: English, Irish, Scots, Dutch, Swedes, Poles


  • Napolean (snow in September)
  • Spanish Armada
  • American Revolution
  • victory or defeat often is hinged on climate

1.8.13French revolution

  • 1787: coldest winter
  • french wanted bread, grain, and cereal

1.8.14Volcanos Tambora - 1815
  • Most powerful volcanic eruption
  • Caused 'year without a summer'
  • brown snow in italy - 1883
  • loudest sound in history
  • temp dropped 1.2 degrees in Iceland - 1783
  • Ash fallout
  • French revolution 6 yrs later
  • Coldest winter on record
  • killed quarter of population in Iceland (Iceland population not stable until after WW2)
  • Sulfur didn't circulate to southern hemisphere

1.8.15Glacier growth

  • Agaissiz presented theory of ice age when glaciers were receding

1.8.16end of lil ice age - 1850

  • perhaps fewer volcanos
  • perhaps greenhouse gas fluctation
  • perhaps natural fluctuation in thermohaline circulation
  • perhaps less radiation

1.9other definitions

younger dryas
cold snap 11k years ago, lasted 1.2k yrs. freshwater influx stopped thermohaline circulation

1.9.1centers of domestication

  • 1) Central New World - [corn, bean, potato, yam, squash, banana, llama, dog, pig, turkey]
  • 2) Middle East - [wheat, barley, lentils, pea, pig, goat, donkey, horse, camel, dog, chicken]
  • 3) China - [rice, soybean, millet, yam, pig, chicken, water buffalo]

1.9.2mammoth extinction

  • 1) clovus point spear
  • 2) ice age ending
  • 3) disease