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GEOG 2210 > Test 2 > Flashcards

Test 2 Flashcards

1
Q

What are the 2 fundamental motions that affect us?

A
  1. Rotation on its axis
  2. Revolution around the sun
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2
Q

What does the Earth’s rotation control?

A

= controls our day / night

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3
Q

What does the Earth’s Revolution around the sun influence?

A

= controls the summer/winter

Summer:
=closer to sun
- longer sunlight

Winter:
= farther from sun
- sunlight is diffused

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4
Q

MIDTERM: What are the 3 Properties that fluctuate?

A
  1. Tilt
  2. Eccentricity
  3. Axel Precession (“Wobble”)
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5
Q

Definition: Tilt

A

“a metronome”
- oscillates between 22.2 and 24.5 degrees
1 cycle takes 41 000 years

= in phase between hemispheres

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6
Q

MIDTERM: how long is 1 cycle of Tilt

A

= 41, 000 years

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7
Q

What is our current tilt? is it increasing or decreasing?

A

23.5 degrees
= decreasing (tilt is getting more vertical)

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8
Q

Definition: Eccentricity

A

“more circular / elliptical”
= sometimes closer and farther to sun
=how elliptical is the earth’s orbit around the sun

  • may be due to the Gravitational pull of Saturn and Jupiter

Controlled by 2 dominent periodcites:
- 100,000 and 413,000

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9
Q

MIDTERM: How long is 1 cycle of eccentricity?

A

100,000 years

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10
Q

Definition: Axel Precession

A

= wobble on the axis

Period: 23, 000 years

= out of phase between hemispheres

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11
Q

MIDTERM: How long is 1 period of Precession?

A

23, 000years

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12
Q

MAX Tilt + Precession coincide with Perihelion or Aphelion?

A

Perihelion = closest to the sun

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13
Q

Where can you find MAX Warming?

A
  • in the N hemisphere
    = when the summer solstice coincides with perihelion
  • MAX Tilt + precession
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14
Q

What do the 3 fluctuating properties result in?

A

= these result in a shift in position of the equinoxes (and solstices) around the Earth’s orbit every 23,000 years

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15
Q

What happens every 23,000 years?

A

= the shift in the position of the equinoxes (and solstices) around the Earth’s orbit

results in a differing amount of sun in the summer

= precession

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16
Q

Definition: Aphelian

A

= when the Earth is in the farthest position from the Sun

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17
Q

Definition: Perihelion

A

= when the Earth is in the closest position towards the sun

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18
Q

What is the importance of orbital properties?

A

= these determine how much radiation is received

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19
Q

Definition: Insolation

A

= Radiation received at the top of the Earth’s atmosphere

Units: Watts per square metre (W/m2)

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20
Q

T/F: The N/S Hemisphere gets more sunlight all year round and the Equator gets more short term

A

FALSE

The Equator gets more sunlight all year round

The N/S Hemisphere gets more short term sunlight

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21
Q

____ has a stronger affect at higher latitudes than ____

a) Tilt
b) Precession

A

Tilt has a stronger affect at higher latitudes than Precession

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22
Q

Out of tilt, precession, and eccentricity, which is the least important?

A

Eccentricity = least important
- approximately 0.2% incoming solar radiation
- small difference in sunlight

Tilt + Precession:
- approximately 10% difference in long-term mean

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23
Q

Tilt is in phase / out of phase between hemispheres?

A

In phase

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24
Q

T/F: Tilt affects the N/S hemispheres differently.

A

FALSE: It affects both hemispheres equally

Both hemispheres get hotter when they face the sun

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25
Q

T/F: Pression affects the N/S hemispheres differently

A

TRUE:

When the S hemisphere is warm, the N hemisphere is cold

When 1 hemisphere is in aphelion, the other is perihelion.

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26
Q

If summer occurs at perihelion it will be dimmer/brighter, but longer/shorter

A

If summer occurs at perihelion, it will be brighter but shorter

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27
Q

What is the caloric isolation seasons

A

= divide year into halves based on total isolation

182 brightest days vs 182 dimmest days

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28
Q

T/F: Tilt is more important at high latitudes

A

TRUE

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29
Q

T/F: Pression is more important at high latitudes

A

FALSE: Pression is more important at low latitudes

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30
Q

Definition: Time Series Analysis

A

= a set of tools and techniques for analyzing time series data
eg. data from tree rings, climate data

eg. Spectral Analysis:
= used to identify dominent frequences of variability
“how strong is the variability”

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31
Q

Definition: Spectral Analysis

A
  • a ,method for time series analysis
    = used to identify dominant frequences of variability
    “how strong is the variability
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32
Q

Why does the real-world spectra never look like the model?

A
  1. because the 41,000 and 23,000 have changed over time
  2. hard to tell with oceans because of mixing
  3. we tend to under sample (aka aliasing)
    - a problem with most climate records. eg ice sediments / oceans
    - results in missing data
  4. the paleorecord = imperfect,
    - cliamte differs in different locations
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33
Q

Definiton: Aliasing

A

=mis-identification of signal frequency during sampling
- aka undersampling
- results in missing data

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34
Q

What data is not under sampled?

A

Data from tree rings

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35
Q

Over the years, how has our tectonic scale changed the earth’s orbit?

A
  1. rotation on the axis is slower
  2. precession = slightly slower
  3. tilt cycle = longer
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36
Q

How are Monsoon Circulations caused?

A

= when there is a really high heat difference from the ocean and land

Oceans have a higher heat capacity than continents
= drived large-scale advection of moisture

Continents are hotter in the summer and colder in the winter (creating summer and winter monsoons)

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37
Q

T/F: Oceans have a lower heat capacity than continents

A

FALSE: Oceans have a HIGHER heat capacity than continents

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38
Q

How are Summer Monsoons formed?

A

In the summer,
- continents = warmer
-oceans = colder

  • air on continents warm up from the evaporation over oceans, resulting in rain –> monsoon
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39
Q

How are Winter Monsoons formed?

A

In the winter,
- continents = colder
- oceans = warmer

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40
Q

Where are Monsoons strongest? and Why?

A

= in the N Hemisphere

  1. B/c there are more continental land masses than in the S hemisphere
    - creates a stronger affect
  2. B/c there are more mountains
    - mountains amplify rising air
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41
Q

Describe the Coriolis Effect

A

In the N Hemisphere:
- Objects moving N will deflect to the right
- Objects moving S will deflect to the left

The opposite will occur in the S Hemisphere.

  • this increases towards the poles
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42
Q

What happens do the the motion of a rotating surface?

A

= objectes in motion will be deflected due to differences in linear velocity

  • causes the coriolis effect
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43
Q

With the coriolis effect, in the N hemisphere, objects moving N will deflect to the ____

a) left
b) right

A

a) right

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44
Q

With the coriolis effect, in the N hemisphere, objects moving S will deflect to the ____

a) left
b) right

A

b) left

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45
Q

Definition: Orbital Monsoon Hyp

A

= orbital changes in solar radiation should influence the intensity of monsoon rains

In the N hemisphere,
hotter summers + more tilt = stronger monsoons

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46
Q

What creates the strongest monsoons?

A

In the N hemisphere with hottest summer + MAX Tilt

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47
Q

What evidence from N. Africa can help explain monsoons?

A

A more intense monsoon = higher lake levels
- water pushed up into N Africa (goes up North)

Less Intense = lower / no lakes
- weak monsoon = pushes up less strong

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48
Q

What are the 3 underlying assumptions for evidence in N. Africa?

A
  1. threshold response
    = when solar radiation goes up, it does not go past a threshold
  2. monsoon strength “a” isolation > threshold (alpha = a)
  3. lake levels “a” strength of monsoon
    = are proportional
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49
Q

Definition: stinky mud

A

= when fresh water with high organic content dumps into less dense salt water resulting in a cap of organic debris

  • fresh H2O (less dense) = from nile river
  • mediterranean (more dense)= salt water

= this results in “a cap” = prevents oxygen going down into the deep water –> results in anaeobic decomposition (aka stinky mud)

low salinity lid separates from Oxygen-rich deep water

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50
Q

What happens to the fresh H2O diatoms in the Summer?

A

Summer = high evaporation

Fresh H2O diatoms (from continental lakes)
- Diatoms = single-celled algae (a common marine phytoplankton) is exposed to wind erosion

  • These diatoms end up in the N. Atlantic from fresh water lakes that dry up.
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51
Q

Definition: Diatoms

A

= single-celled algae
- a common marine phytoplankton
- deliver 23,000 years

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52
Q

MIDTERM: Definition: CLIMAP

A

= when different people come together to map 1 point in time

53
Q

MIDTERM: What are the 3 lines of evidence for the Orbital Monsoon Hyp

A
  1. stinky mud in the Mediterranean
    - anaerobic when fresh H2O comes up
  2. pond filling in N. Africa
  3. Fresh water diatoms
    - strong monsoons = winds blow into N. Africa
    –> deliver water from atlantic to ponds
    –> weak winds / monsoons - lakes dry out
54
Q

When looking at the N African Paleorecord, Sediment cores fro the Atlantic ocean south of the Equator shows a _________ year cycle

A

23,000 year cycle

55
Q

What evidence is there to support a 23,000 year cycle of the N African Paleorecord?

A
  1. Monsoon Phasing
    - the last monsoon maximum lagged isolation peak by approximately 2K years.
    = expect to be out of sync between hemispheres. B/c
  2. a delay because of ice sheets
  3. misalignment betewen monsoons and equinox
    - sun comes up but it takes time for the system to warm up
  4. Regional Evidence
    = there are different monsoons across the world
  • Asian monsoon = the most powerful
  • Brazillian monsoon = most important in S hemispheres.
    (big delivery of water from ocean to terrestrial regions)
56
Q

How does Monoon Phasing support how the N. African Paleorecord has a 23,000 year cycle

A
  1. Monsoon Phasing
    - the last monsoon maximum lagged isolation peak by approximately 2K years.

= expect to be out of sync between hemispheres.

B/c
1. a delay because of ice sheets

  1. misalignment betewen monsoons and equinox
    - sun comes up but it takes time for the system to warm up
57
Q

How does regional evidence support how the N. African Paleorecord has a 23,000 year cycle.

A

Regional Evidence
= there are different monsoons across the world

  • Asian monsoon = the most powerful
  • Brazillian monsoon = most important in S hemispheres.
    (big delivery of water from ocean to terrestrial regions)
58
Q

Precession is expected to be out of phase between the hemispheres. What does this mean for teh N and S hemispheres?

A

When the N Hemisphere is in Perihelion, the S Hemisphere is in Aphelion

59
Q

What can give a record of monsoons?

A

Speleothems
= are also out of phase
(18O is enriched in brazil, and it is depleted in china

-dry in N hemisphere + wet in S hemisphere
= driven by precession

When there is more energy in the system,
= more 18O is evaporated and ending up in the terrestrial
- 18O evaporates and ends up in ice cores/speleothems/tree rings

Cold Climates:
- have more 18O in the ocean

60
Q

What happens when tilt coincides with Perihelion?

A

=summers will be hotter
=winters will be colder

61
Q

What happens when summers coincide with perihelion?

A

= it points towards the sun and the S. hemisphere has warmer summers

62
Q

What is the conclusion of the orbital monsoon hyp?

A

= it has passed so many tests that it merits the higher status of a theory
- every prediction has been proven true for orbital monsoons and orbital fluctuations
“almost considered fact”

63
Q

Why does the orbital monsoon hyp matter?

A

= relates to rising CO2

64
Q

T/F: In the summer, the land heats up faster than the ocean

A

TRUE:
= mountains + large continental bases help
(= stronger at low latitudes)

65
Q

What can we assume about Monsoons on Pangaea (200My ago)

A

-large continents at low latitudes were driven by monsoons
- low latitudes = assume driven by precession

66
Q

How can you interpret deep lake sediments?

A

= use varves: layers in rock
- normalluy annual
- abundant in carbon

67
Q

How can you interpret shallow sediments?

A

= use fish remains
- get fish scales, located on shallow sediments

68
Q

How can you interpret dried out sediments?

A

= using oxidized cracked footprints

69
Q

What are 3 ways to look at sediments?

A
  1. deep lake sediments: varves
  2. shallow lake sediments: fish remains
  3. dried out sediments: oxidized cracked footprints
70
Q

T/F: tectonic scale processes are shorter than orbital scale processes

A

FALSE: tectonic scale processes are LONGER than orbital scale processes

71
Q

How do plate tectonics affects monsoons?

A
  • lots of uplifting from mountains result in cooling –> dampen monsoons

Now, monsoon systems is weaker (b/c of plate tectonics)
+ the threshold for monsoons is surpassed more often in the past. Less in the present

72
Q

Describe how ice accumulation occurs?

A

Glaciers develop wherever
(polar position hyp = glaciers occur at high latitudes)

  1. accumulation exceeds ablation
  2. accumulation occurs up to the Mean Annual Temperature (below 10 deg C)
  3. High Temp = limits accumlation
    - due to increased rain (rain helps melt ice)
  4. Low Temp = limits accumulation
    - due to low moisture (cool air doesn’t warm water = low moisture)

MAX accumulation: a rate of 0.5m per year

73
Q

How does High T limit accumulation

A

= increased rain
- rain helps melt ice

74
Q

How does Low T limit accumulation

A

= low moisture
(cold air doesn’t warm the water = low moisture)

75
Q

MIDTERM: What are the 3 main mechanisms of Ice accumulation?

A
  1. Solar warming
  2. Advection
    - wind from polar
  3. Calving
76
Q

Defintion: Ice Mass balance

A

= the difference between accumulation and ablation
aka “mass balance”

accumulation - typically in winter
ablation - typically in summer

Net positive mass balance:
- alpine at high elevation

Net negative mass balance:
- low elevations

Ice extent = ice balance over time

77
Q

Defintion: Ice extent

A

ice balance over time

78
Q

What does it mean for glaciers if our climate is static

A

Climate = static
- meaning glaciers will continue to gain mass and deliver across a slope

79
Q

Do glaciers grow in the winter or summer? Why not the other?

A

= winter

Winter:
- high latitude winters ae always cold
- insolation is always low in winter

Summer:
- hot summers will melt snow, no matter how much falls
-hot summers drive interglacial cycles more than winter
-low insolation results in less ice ablation

80
Q

MIDTERM: Milankovitch Theory

A

= hypothesized that the 65 deg N is the most critical latitude
- has large land masses
-latitude where ice develop first and melts lask

conclusion: ice sheets grow when summer insolation at 65 deg N = minimal (grow at N hemisphere)
- low tilt
- in N hemispere: Summer solstice at aphelion
-orbit = more eccentric (more elliptical)

overall hypothesis: the earth-sun geometry drove what is happening with glaciation

81
Q

In what conditions can ice sheets grow (Milankovitch theory)

A

= when summer insolation at 65 deg N is minimal
- grow in the N hemisphere ( when summer solstice is at aphelion)
- low tilt
-orbit is more eccentric = elliptical

82
Q

What happens when solar insolation is high?

A

= more melting

83
Q

What do Ice Sheet Models display?

A

= consider a 2D model of ice growth at high latitudes

84
Q

Definition: Phase lags?

A

= the delay in 1 cycle relative to another

85
Q

What is the phase lag between 65 deg N and ice volume?

A

= about 10K years

86
Q

What are the bedrock responses to ice sheets?

A
  1. ice builds up on continental terrain
  2. will depress the surface underneath (aka the underlying bedrock)

= this will lower the ice sheet

  1. when the sun melts the ice sheet, the land will spring back, resulting in a cycle.

1 cycle is 30, 000 years

= a positive feedback loop

87
Q

How long is 1 cycle of the bedrock response to ice sheets?

A

30, 000 years

88
Q

What did Milankovitch not hypothesize?

A
  1. glaciers can self maintain at a certain height (when glaciers get big enough)
    - if below, they melt
  2. insolation lags: lag between insolation and ice volume
  3. phase lags
    - didn’t anticipate that the phase lags are different between tilt and precession
89
Q

Definition: Insolation Lags

A

= lag between insolation and ice volume

90
Q

Are bedrock responses to ice sheets a positive / negative feedback loop?

A

= 2 positive feedback

-more ice building at a certain height = more growth

-more ice melting = below the standard ground level = more ice melting

91
Q

When was the start of the Pleistocene?

A

= 2.75MYA

92
Q

How long is the lag between glaciation and non-glaciation, and then what has it shifted to?

A

41K years and then it shifted to 100K years

93
Q

What are 3 hypotheses of the shift in period between glaciation and non-glaciation?

A
  1. there are two 41K cycles, not one 100K
  2. b/c they were wet based glaciers that transitioned into dry-based
    -sediments don’t exist anymore because of many wet-based glaciers
  3. didn’t predict that CO2 drops
    (ice sheets grow with lower insolation, then CO2 grops making ice sheets grow = colder - positive feedback loop)
94
Q

Explain how wet-based glaciers can transition into dry-based glaciers?

A

Wet based glaciers:
- easy to slip over mud / sediments

-lots of wet based glaciers = less sediments + mud
= leads glaciers to grind over bedrock (= dry based glaciers)

95
Q

Are CO2 levels and ice growth a positive or negative feedback loop?

A

= positive
- ice sheets grow with lower insolation
- CO2 drops = ice sheets grow
= colder –> ice sheets grow

96
Q

What are ice flow models based on?

A

=based on esitmated rates of accumulation physics of ice flow

97
Q

MIDTERM: Ice bubbles are trapped (or not entrained/ exchange with the surface below ____m?

A

35m

98
Q

What 2 areas could explain the missing CO2 from the atmosphere? What is the most proabbly answer?

A
  1. Vegetation
  2. Deep Ocean

Best Guess Deep Ocean

99
Q

Why do we NOT think that CO2 went into vegetation?

A
  • terrestrial vegetation reduced by 25% (probably less vegetation during glaciation
  • during warmer climates, soils don’t store as much carbon

-all carbon from vegetation is also missing
(so there is missing CO2 from biosphere and atmophere)

100
Q

Why DO we think that the missing CO2 from the atmosphere went into the Deep ocean?

A

= looked at the benthicforaminifera
- live at the bottom of the ocean + absorb CO2 from the atmosphere

= showed a signal between 13C and temp have a feedback where temp amplifies 13C. Temp tracks carbon

101
Q

T/F: 13C tracks temp

A

FALSE: Temp tracks carbon

102
Q

What is the global mean 13C from benthic foraminifera?

A

= -0.35% to -0.4%

103
Q

What is the difference between Carbon 12, Carbon 13 and Carabon 14?

A

12C = stable and common (98.9%)
13C = stable but rare (1.1%)
14C = unstable (reerts to 14N)

104
Q

What are 3 ways Carbon could get into Oceans?

A
  1. Increased CO2 Solubility
  2. Biological transfer from surface waters
  3. Changes in feep water circulation
  4. increased CO2 solubility
    =oceans absorb CO2 when it gets colder
    - colder fluids exchange gas more readily than warmer
    - colder water dissolves CO2 more readily
    - salty water = less readily than fresh water

= net effect: 14PPM is removed
- ice core reconstructions suggest approximately 90PPM

  1. Biological transfer from surface waters
    - surface waters = more productive (more plants that photosynthesize) –> more photosynthesis = more pumped into the deep ocean
    = increased transport of carbon
  • may be less evaporation + less clouds = more photosynthesis?
  • most photosynthesis in shallow waters against continental margins (nutrients are from rivers in the form of dust in colder regions)

-most productivity at poles
Iron fertilization Hyp:
= stronger glacial winds + increased aridity = more iron-rich dust into the oceans
- dust from continents are fertilizing plants in ocean
= limited by iron, the dust storms fertilize the oceans = more productivity = moving carbon out of the atmopshere

  1. Changes in deep water circulation
    =the LGM led the oceans heat transport to sped up –> increased CO2 into deep ocean
    - associated with glacial periods
    - no mechanisms (if there is enough chnage in terrestrial env during, you don’t need ocean fertilization, you existing Carbon and pump it down faster = reduced level of CO2
  • less N atlandtic deep water formation + more antarctic deep water formation
    = more deep water formation coincides with glacial (less with interglacial)
    -stronger antarctice overturning = more production _ downward C pumping

-Polar Alkalinity Hyp:
= Antarctic deep water is more corrosive = more carbonates (and then they will react with CO2 = less CO2 in atmosphere)

105
Q

How can we estimate the age of ice and age of air bubbles?

A

= how ever long it takes for 35+ m of ice to form

  • approx 200 - 2000 years
106
Q

What is the Iron Fertilization Hyp

A

= stronger glacial winds and increased aridity –> mnore iron-rich dust entering oceans
=dust from continents are fertilizing plants in the ocean

  • productivity is limited by iron (dust storms fertilize the oceans = more productivity = moving more carbon out of the atmosphre)
107
Q

Where is Methane = produced?

A

= anoxic environments
(w/out oxygen)

  1. wetlands
    - Wetland hyp = stronger monsoons = more wetlands
  2. permafrost
108
Q

What are the orbital scale climate roles of CO2 and CH4?

A
  1. 23K year cycle
    -mostly in phase with isolation (monsoons + methane)
  2. 41K year cycle lags isolation
  3. no signal at 100K
109
Q

Are GHGs a forcing or feedback?
AKA is temp a driver or is methane a driver?

A

= Probably both

  • GHGs amplify the effect of isolation on glaciation at 23,000 year scale
    (not as much at 100K scale
  • glaciation afffect GHG abundance at 41,000 year scale

-reason = unknown (zeev thinks it is tilt)

110
Q

T/F: Once you change the ice sheet, you can change the climate

A

= TRUE:

Ice sheets are an internal forcing

111
Q

How are Ice sheets internal forcing agents?

A
  1. high elevation
    - ice sheets have high elevation
    -thin air above
  2. high albedo (positive feedback: ice = high albedo –> reflects heat = colder –> more ice growth )
  3. Low temp (takes a lot of energy to turn water into ice)
  4. low moisture
    - takes a lot of energy to sublimate and melt ice
112
Q

During glacial periods, are deep oceans high/low in 18O and 13C

A
  • high 18O
    -low 13C
113
Q

During interglacial periods, are deep oceans high/low in 18O and 13C?

A
  • low 18O
    -high 13C

12C gets back into atmosphere and into plants

114
Q

Describe the Polar Alkalinity Hyp

A

=antarctic deep water is more corrosive = more carbonates

(and then they will reactice with CO2 = less CO2 in the atmosphere)

115
Q

What is the Wetland Hyp?

A

stronger monsoons = more wetlands

116
Q

What are the 2 Milankovitch theories?

A
  1. Milankovitch cycles change both ice and GHGs
    = changes in solar forcing = change decay and growth of ice and the composition of GHGs
  2. Milankovitch cycles change growth and decay of ice sheets. The change of ice sheets then cause GHGs
117
Q

What cycle is driving Summer isolation?

A

= 23K year

118
Q

What cycle is driving ice volume in the Early Pleistocene?

A

= 41K year - probably driven by something at high latitudes

119
Q

What cycles is driving ice volume in the Late Pleistocene?

A

= huge strength at the 100K scale

  • could be some lags of the 41year cycle
120
Q

What are the 3 possibilities for the 41K year glacial world (in the Early Pleistocene)?

A
  1. insolation variability weak at 23K year
    -summer insolation increases at 23K year are cancelled by shorter summers
    - high tilt = hotter summers
  2. interhemispheric cancellation of 23K year signal
    - N and S hemisphere glaciers have a 23K year signal
    = signals cancel out
    - but if it is a 23K, it should be out of phase (eg. S has huge ice sheets and N has none) == but this is wrong
    - N Hem ice did vary at the 41K year preiod based on the Benthic Foraminifera (strong variation at the 41K year)
  3. CO2 feedback at 41K year
    - b/c of a positie feedback from CO2
    - GHGs amplify the effect of insolation on glaciation at the 23K year scale
    - glaciation affects the GHG abundance at the 41K year scale

prediction
- a 41K year cycle at high latitudes where there is a lot of permafrost – canada

121
Q

Definition: Glacial Flour

A

= glaciers grind fown sediment

122
Q

How has the climate signal tranferred south?

A

= evidence of 100K year cycles in pollen records

-led to the South pacific mystery

123
Q

T/F: high ice volume has less grasses

A

FALSE: high ice volume has lots of grasses

124
Q

Define the South Pacific Mystery

A

= why/how is the N hemisphere ice signal transferred south?

125
Q

What are the 3 predictions of how the N ice signal transferred south?

A
  1. Changes in sea level
    - sea level drops
    = atmospheric cooling
    = oceans get further away –> the ocean affect is diminished
  2. Changes in deep water circulation
    -thermohaline circulation
    -changes in 13C
    -may have less heat transfer = S gets colder
  3. Changes in GHGs
    - ice ages = less methane /CO2 = colder cliamte
    - more cooling at polar regions
126
Q

Why do N icew sheets vary at the 100K year?

A

= ice interations with bedrock

  1. could take 100K years for the ice to push bedrock down
  2. ice sheet sliding
    - Early Pleistocene: water under ice sheet = good for sliding
    - Milankovitch driven
    - all mud is gone = no sliding = no small glaciers form = the ice will get bigger/taller = restricted to N and do not melt becuse they are above the equilibrium line
127
Q

What is the supporting evidence to why N ice sheets vary at the 100K year?

A

= Moraines

128
Q

What is the most probable of the least likely reasons of why N ice sheets varied at the 100K year?

A

= interactions with GHGs
- b/c ice does not completely melt between 41K year cycles, CO2 effect is amplified

this should have resulted in a 82,000 year cycle

129
Q

Glacial cycles at 41K year (and especially the 100K year) are proabbly controlled by _______

A

timing of ablation

GEOG 2210 (3 decks)

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