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GEOG 2210 > Test 1: > Flashcards

Test 1: Flashcards

1
Q

What is the difference between weather and climate

A

Weather
- daily

Climate
-over a period of time

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2
Q

Why can we not rely on climate records?

A
  1. They are short
    - measure up to 250 years max
  2. They are sparse
    - biased around the N. atmosphere
  3. measurement systems change consistently
    - new advancing technology
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3
Q

what is equilibrium

A

-inputs = outputs

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4
Q

Definition: Response Time:
- how is it measured?

A

= time it takes the climate system to respond to some imposed change in forcing

measured:
- by the time it gets to 50%

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5
Q

what if the forcing is slower?

A

=climate system tracks the forcing

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6
Q

what if the forcing is faster?

A

= little response
eg. volcanoes

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7
Q

the length of “on” time is (directly or indirectly) related to the magnitue of response

A

Directly related

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8
Q

Definition: Flux Response

A

= the flux intensity of a forcing
- there can be a lag (eg. heat and H2O)

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9
Q

T/F: system components have DIFFERENT reaction time to the same forcing

A

TRUE

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10
Q

Climate forcing in cycles can result in cyclic responses from the climate system. What is this known as:

A

Feedbacks: response of a system to a change in itself

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11
Q

T/F: Responses will only track/closely follow the force(s), not lag behind

A

FALSE: Some responses will track/closely follow and some will lag behind.

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12
Q

What feedback amplifies?

a) Positive
b) Negative

A

a) Positive

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13
Q

What feedback reduces or dampens?
a) Positive
b) Negative

A

b) Negative

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14
Q

The Earth’s system is known as a:
a) Positive
b) Negative

A

b) Negative

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15
Q

Definition: Threshold

A

= the system can persist to a certain point (the threshold)

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16
Q

Definition: Weather

A

= the state of atmosphere at a point in time

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17
Q

Definition: Climate

A

= Statistics of weather over long-term
-mean
-variability/trends
“What’s expected”

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18
Q

What measures climate + a main component? Where should you not put this device?

A

Weather stations
- use electronic thermometers (more sensitive than mercury thermometers)

Not good beside a tree
-absorbs radiation
(For rain gauges, the tree can block certain areas)

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19
Q

How has measuring atmospheric climate advanced over time

A
  1. kites
  2. balloons
  3. satellites
  4. radiotelescopes
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20
Q

How old is the Earth?

a) 4.45B years
b) 4.55B years
c) 4.58B years
d) 4.75B years

A

b) 4.55B years

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21
Q

What are the climate system’s components?

A
  • air
  • H2O / ice
  • land
    -vegetation
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22
Q

What are the 2 fundamental climate forces?

A
  1. Tectonic forces
  2. Orbital forces
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23
Q

What are the 2 tectonic climate forces?

Are these slow/fast processes

A
  • earth’s internal heat
  • change topography

= slowest process

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24
Q

What are orbital forces?

A

= variations in earth-sun geometry

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25
Q

If the force source is the Sun, what changes/responses can you expect?

A

Changes in:
- plate tectonics
- earth’s orbit
sun’s strength

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26
Q

If the force source is the Sun, what climate variation can you expect?

A

Changes to:
- glaciers: –> H2O levels
- vegetation
- ocean
- land surface

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27
Q

Why is there more solar reflection at the south poles?

A

Because of Antarctica (a large continental landmass)

the greater angle of incidence, the more reflection (ie. at the n/s latitudes)

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28
Q

T/F: the N hemisphere gets more sunlight than the equator for a short amount of time.

A

FALSE: the SOUTH hemisphere gets more sunlight than the equator for a short amount of time.

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29
Q

Why is land more variable than water?

A

Soil has a higher thermal conductivity than water (therefore water gets colder with little sunlight)

Water mixes from prevailing winds + gravity

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30
Q

T/F: Warm air condenses into clouds and will go polewards

A

TRUE: heat transfers polewards

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31
Q

Definition: Proxy Records
+ give an example

A

= give insight into climate of that time period
- existed long before weather stations

Eg. ice cores, pollen, glaciers, tree rings, 18O, etc

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32
Q

What are the 2 stable isotopes of Oxygen?

A

Oxygen 16 and Oxygen 18

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33
Q

T/F: O18 is heavier than O16

A

TRUE: b/c it has more neutrons

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34
Q

T/F: 16O is more rare in the atmosphere

A

FALSE: 18O is more rare b/c it is harder to evaporate

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35
Q

If there is more 18O, what does this imply about the climate?

A

= warmer climate

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36
Q

What is the best available record for over 99% of geological time? Why?

A

Sediments - b/c it is composed of chemical, physical, and biological material that is usually deposited in water

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37
Q

Pros and Cons to using deep-sea sediments for interpreting climate?

A

Pros:
- deep ocean waters = stable with continuous deposition

Cons:
- record = only to 100M years due to plate tectonics
(takes 100M years for subduction to occur)

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38
Q

Definition: Loess

A

= silt-sized grains transported by wind to specific regions of the earth
- contain some clay and sand

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39
Q

MIDTERM: How would you interpret climate from Loess deposits?

A

Deposits will give data for the last 3M years
- deposits coincide when climates are cold and dry
- oldest deposits = bottom

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40
Q

Why were there no Loess deposits in Canada?

A

b/c there were ice sheets

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41
Q

What ways can you interpret climate using glacial ice?

A
  1. air bubbles - determine composition of atmosphere
  2. dust
  3. see 18O water - determine temperature
  4. pollen / organic matter - see wind direction
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42
Q

What are 2 limitations to using glacial ice to interpret climate?

A
  1. the big time scale are only in Greenland and Antarctica
  2. currently disappearing
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43
Q

How can we use tree rings to measure climate?

A

= measure the amount fo 18O
18O = enriched (lots) = warm climate

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44
Q

How can we use Geoducks to interpret climate?

A
  1. long lived (up to 168 years)
  2. growth rings are produced in the winter
  3. abundant along the west coast
  4. shell growth = sensitive to climate (sea ocean temperature)
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45
Q

MIDTERM: What are the 3 Dating Climate Records?

A
  1. Radiometric
  2. Counting
  3. Correlative
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46
Q

What components are looked at with Radiometric dating?

A

= based on radioactive decay of unstable isotopes
Older: Uranium, Lead
Recent: Carbon to Nitrogen

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47
Q

Explain how Carbon can get converted to Nitrogen

A
  1. 14C (unstable isotope) is formed when 14N is hit by a neutron (cosmic radiation
    - 14N loses 1 proton
    - 14C wants to revert back to 14N
  2. 14C bonds with O = CO2
  3. CO2 - taken up by plants + animals
  4. Look at the rate of decay from 14C to 14N
    - measure how much 14C is left when transitioning
  5. 14C decays back into 14N by either
    - finding another proton = 14N
    - when an organism dies
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48
Q

What is the half life of 14C?

a) 5580
b) 5560
c) 5780
d) 5790

A

c) 5780 years (5000-6000 years)

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49
Q

What happens to the 14C that was once 14N?

A

= it disappears into the atmosphere

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50
Q

What happens to the lead that was once Uranium?

A

= the lead stays as a solid (stable), which can be measured

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51
Q

How do you perform counting dating?

A
  • can count annual (or sub-annual) layering
    (1 band = 1 year)
    Eg. trees, coral, speleothems, lake sediments
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52
Q

How do you perform correlative dating?
+ give an example

A

= relating an unknown proxy series to a known chronology
“happen at the same time as other things”
-find the same species in 1 sediment that was dated and compare to 1 unknown

Eg. Index fossils
- we can associate samples with others we beleive are in the same time scale

Eg. earth’s magnetic polarity

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53
Q

Pros and Cons of using Index fossils:

A

Pros:
Widespread - can compare fossils from other continents / locations

Cons:
Need to be short lived fossils
- Need fossils that pop up in sediment for a short amount of time and then disappeared.
- can associate that fossil / species with a specific time frame
-better to know it was their 100 years vs if it was 100-10 000 years.

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54
Q

How would you use Earth’s magnetic polarity to describe climate?
- Give an example

A
  • orbital variations have a known periodicity + have a measureable impact on climate
  • earth’s polarity has reduced over time + reverses episodically
  • match magnetic polarity with rock and time, then with the climate

Eg. Magma with Iron comes up and redirects N/S

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55
Q

What are the problems with using weather stations?

A
  1. only data btwn 50-200 years
  2. changed instrumentation
  3. difference between ground-based and satellite-based
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56
Q

How much data can be interpreted by tree rings?

A

= can get data from the last 1K years

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57
Q

How are speleothems used to interpret climate?

A

= from stalagmites from the ground

  • data from the last 700K years
    (long record but mixing could occur = unreliable)
  • not certian if rings in sediment are annual or not
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58
Q

Definition: Half-life

A

= time it takes for 50% of parent isotope to decay into the daugther isotope

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59
Q

What are the 2 categories of Climate Models

A
  1. Physical: ocean/atmosphere, ice, land surface
  2. Geochemical: biochemical components of the earth’s system
60
Q

Definition: Physical Climate Models

A

= models that create a simulation of the Earth’s climate (based on our best understanding on the physics and our best computing power)

  • tracks change of energy (energy into system - energy out of system)
61
Q

MIDTERM: What are the 2 reasons why we use Physical Climate Models?

A
  1. Can test hyps in models that we can’t do in real life
    - test hyps about observed climate change in the past
  2. Make predictions about the future
    - can do predictions in the present (instead of waiting for it to happen naturally)
    Eg. predictions about climate change
62
Q

For any system, we can say the Change of Energy is equal to

A

= Energy into the system - energy out of system

63
Q

What are the 4 steps to the “Simplest Equilibrium Model of the Earth”

A

Step 1: 1-D climate model: Add layers to the atmosphere
- no land-masses / oceans

Step 2: Add latitudinal differences (equator = more solar radiation)
- exchange energy / mass horizontally
- head from equator moves to the poles

Step 3: 2-D energy balance model
- = temperature distribution

Step 4: 3D climate model: add seasonal cycle - increasing levels of complexity
- make the system cover the whole earth
- add more vertical levels
- add an ocean, plants, ice, clouds

64
Q

Definition: Geochemical Models

A

= Models used to track Earth’s chemicals as they flow through the climate system.
Eg. sediments, ions, C, O, N, etc

  • often coupled to vegetation models
  • driven by physical models

-tracks fluxes:
input flux –> reservoir size –> output flux

65
Q

In the “Simplest Equilibrium Model”, what is Step 2?

A

Step 2: Add latitudinal differences
- equator gets more solar radiation
- exchange energy / mass horizontally
- heat from equator moves to the poles

66
Q

In the “Simplest Equilibrium Model”, what is Step 1?

A

Step 1: 1-D climate model: Add layers to the atmosphere
- no land-masses / oceans

67
Q

In the “Simplest Equilibrium Model”, what is Step 3?

A

Step 3: 2-D energy balance model
- = temperature distribution

68
Q

In the “Simplest Equilibrium Model”, what is Step 4?

A

Step 4: 3D Climate Models: add seasonal cycle - increasing levels of complexity
- make system cover the whole earth
- add more vertical levels
- add an ocean, plants, ice, clouds

69
Q

T/F: Geochemical Models track fluxes

input flux –> reservoir size –> output flux

A

TRUE

70
Q

MIDTERM: Definition: Residence Time

A

= amount of time it takes for an element to move from 1 reservoir to another
“avg time it takes for a chemical to pass through a reservoir”

71
Q

What are 2 problems supporting why the Earth wasn’t always habitable?

A
  1. Early sun was 25% less bright than the present
    = runaway ice house: freezing of all surface water
    - Faint Young Sun Paradox
  2. Venus receives about half the surface sunlight but is way hotter.
    “less sun, but is hotter”
    - water helps reglate surface temp
72
Q

Where can you find Carbon on Earth?

A
  • rocks
  • coal
  • gas + oil
  • vegetation
  • atmosphere («1%)
    (vs Venus: has 96% CO2 = hotter)
73
Q

How much Carbon is in the atmosphere?

A

«1%

74
Q

Definition: The Greenhouse Effect

A

= CO2 absorbs longwave radiation

75
Q

Definition: Faint Sun Paradox

A

= assumes the Early Sun was 25-30% less bright

  • should’ve resulted in freezing of all surface water –> runaway ice house”
  • high albedo
  • no clouds + liquid water b/c water is all frozen
76
Q

What is the theory of why the Earth wasn’t frozen for 3B years?
+ what is the assumption?

A

Assumption: something happened that made the earth warm back then, that isn’t happening now

= Thermostat Hypthesis
- some process heats the earth when it’s cold (and vise versa)

77
Q

What is the theory of why the Earth wasn’t frozen for 3B years?
+ what is the assumption?

A

Assumption: something happened that made the earth warm back then, that isn’t happening now

= Thermostat Hypthesis
- some process heats the earth when it’s cold (and vise versa)
- assume it’s the GHG Effect

78
Q

Explain how Volcanic Activity could be the Earth’s Thermostat.

A

Early in Earth’s History - Lots of Volcanic Activity
–> High CO2 in atmosphere = warming temperature

As the sun got brighter = slower warming
–> High rates of weathering –> less CO2 in atmosphere = relative cooling

79
Q

How many years woudl it take to absorb all carbon in volcanoes if all volcanic activity stopped?

a) 0.5 years
b) 1.0 years
c) 1.5 years
d) 2.0 years

A

c) 1.5 years

80
Q

What is believed to be the balance between carbon in the atmosphere and in the reservoirs?

A

= Chemical Weathering

Warmer:
= CO2 rise –> more organic acids form (more erosion / weathering)

Colder:
= more CO2 kept in the atmosphere

81
Q

What are the 3 important factors for chemical weathering?

A
  1. Temperature (cold = less weathering)
  2. Precipitation (More water = more weathering)
  3. Vegetation (more organic acids = more chemical weathering)
82
Q

What environment would be optimal for lots of chemical weathering

A
  1. Warm Temperature
  2. More Precipitation / Water
  3. More Vegetation ( More organic acids = more chemical weathering)
83
Q

What would happen to chemical weathering if there were no plants?

A

No plants = no organic acids = Chemical weathering = 1000x slower than today

84
Q

Why would chemical weathering NOT be earth’s thermostat?

A

Initial change would be colder, not warmer

-w/ less sun: cold environment, slower hydrologic cycle + less vegetation = less chemcial weathering

85
Q

What are 3 Alternative Hypotheses with not much evidence?

A
  1. Early Sun = bigger
  2. Solar Wind = stronger
  3. Decreased Surface Albedo (darker surface)
    - less continental area
    - no vegetation
86
Q

What is the most potent GHG?

a) CH4
b) NH3 - ammonia
c) Water Vapour

A

c) Water Vapour

87
Q

What are the issue of why the Water Vapour Feedback is NOT the Thermostat?

A

It is a Positive Feedback
- the others would be negative

(more evaporation = more heat trapped = more heating = more evaporation = …)

88
Q

Definition: Gaia Hypothesis

A

: Life = Earth’s Thermostat

  • life regulates the climate of the earth in order to maintain a life-supporting cliamte
    (insects, plants, people, etc)
  • Vegetation: critical role in the Carbon Cycle
89
Q

What are 3 problems with the Gaia Hypothesis?

A
  1. There was probably no life present during the early Faint Sun period
  2. There is no selection pressure
  3. US (people) - people do not regulate the climate
90
Q

What was the results of the thermostat” malfunction

A

= signs of near global glaciation (850-550M years before present) = glaciers

91
Q

What happened to the carbon after glaciation?

A

= carbon was left in the atmosphere = frozen

92
Q

Out of all the options, what is most likely to be the Earth’s Thermostat (and responsible for warming of the earth’s atmosphere)?

A

= Carbon in Plate Tectonics

93
Q

Definition: Continental Drift Hypothesis

A

= Continents started as a supercontinent, Pangaea, and drifted into their current positions

94
Q

What is the evidence for Continental Drift?

A
  1. Continents fit together
    - SA + Africa
  2. Rock Type and Structural Similarities
    - fossil evidence in different continents
  3. Paleoclimatic Evidence:

Mountains:
- appalachian mountians has the same rock type found in africa
-common age mountains

Glaciation
- glaciation: in areas that are now tropical (eg. africa - could’ve been further south to explain glaciation)
- common glaciation evidence: spread out from antarctica into other continents

95
Q

What is Wegner’s Dilemma? + who solved this?

A

= good evidence on continental drift, but no mechanism
- solved by: Hess (Marine Geologist)

96
Q

What was Hess’ findings?

A
  • saw sea floor spreading when making a detailed map of the sea floor
  • saw areas of magma getting out of earth’s core

-Earth’s upper mantle has convection = sea-floor spreading
Evidence:
- see episodic reversals in volcanoes (iron would point north)

97
Q

How would the climate during Pangaea differ from today?

A
  1. continents were in different climate zones in the past
  2. ocean circulation was different
    - 1 big water mass: oceans were not divided
  3. CO2 outgassing may have been different
  4. Past Glaciation
98
Q

What is the Polar Position Hypothesis?

A

= past glaciation occured when the continents were near the poles (for episodic glaciation)

99
Q

Why is the Polar Position Hypothesis inconsistent?
+ what new hypothesis can we make?

A

= there were no ice sheets in continents that were in the polar region

New hyp: High latitude is probably necessary “but not a sufficient condition” for glaciation
- need GHGs

100
Q

What is the Missing Component for Polar Position Hypothesis? How?

A

=GHGs

101
Q

What are the 2 hypotheses of why GHGs were so abundant?

A
  1. Sea floor spreading hyp (BLAG)
  2. Uplift weathering hyp - Control of CO2 by Chemcial Weathering
102
Q

What is the BLAG Hyp?

A

= rapid seafloor spreading caused more CO2 emissions

-rates of speading = highly variable

103
Q

In the BLAG hypothesis, what will happen if there is FAST sea floor spreading?

A

= more precipitation
–> more vegetation
–> more chemical weathering
= take CO2 from atmosphere (reduces)

104
Q

In the BLAG hypothesis, what will happen if there is SLOW sea floor spreading?

A

= colder climate
–> less vegetation + less precipitation
= CO2 is added to the atmosphere (warmer)

105
Q

What is the Uplift-Weathering Hypothesis?

A

= Control of CO2 by Chemcial Weathering
“Chemical Weathering is the INITIAL DRIVER of climate change, not consequence”

  • rate of chem weathering: determined by availability of fresh rock
  • young sediments weather more quickly
106
Q

Why do young sediments weather more quickly?

A

= becuase they are highly prone to rapid weathering
- steep slopes
- mass weathering
- high precipitation
- glaciers ( turn rock into silt = highly weatherable)

107
Q

At what 2 main plate boundaries do mountains form? + what are mountains impact on CO2

A
  1. Subduction zones
  2. Continental collisions

Mountains forming take CO2 out of the atmosphere

108
Q

How can you interpret climate using Wind River Basins?

A
  1. Morains = 200-130K years BP
  2. Basins are the same identical in rock composition
    - but rock is varibale in age
109
Q

Why don’t periods of rapid uplift lead to runaway ice house conditions?

A

becuase there is continuous mountain building

110
Q

What was the Earth’s climate 100M years ago

A
  1. Seal level: 100m higher
  2. Central SA, N Africa + Australia = flooded
  3. Polar regions = warmer climate
    - found tropical fossils at poles
  4. Dinosaurs
111
Q

Why is the S pole warmer than the N pole?

A
  1. Antarctica is on land, arctic = on water
  2. Antarctica = higher elevation
112
Q

What are the 2 ways of how Paleoclimate is estimated? + examples

A
  1. Temp sensitive plants + animals
  2. Geo-chemcial markers (18O in plankton shells)
113
Q

Definition: Foraminifera

A
  1. bottom dwelling
  2. shells made of CaCO3
114
Q

MIDTERM: What are the 3 categories of error?

A
  1. Model Physics
    -model = wrong
    -computers = inaccurate (not refined)
  2. Boundary Conditions
    - continent positions + atmosphere components change
    - sun position = wrong
    -changes in prognostic variables: variables that were once static (height of mountains, sea level depth, glaciers etc)
  3. Reference Climate
    - wrong target
115
Q

What is the Ocean Heat Transport Hypothesis?

A

: 2/3 heat = transported by atmosphere + 1/3 = by oceans

116
Q

What did looking at pristine shells imply about the climate

A

= it reconstructed the Cretaceous climate as it suggests tropical climate was approximately 5 deg C warmer than previously realized
- shells decrease quicker in warmer water

117
Q

What is Climate sensitivity important for?

A
  1. Ice sheets
  2. Polar bears
  3. Sea level change
    - Global mean sea level = fluctuates by 100m or more over long time scale
118
Q

Definition: LMSL (Local Mean Sea Level)

A

= mean sea level (compared to a local benchmark)
-affected by ocean currents, height of land, amount of water

119
Q

What sea level is affected by ocean currents, heigh of land, and amount of sea level?

a) LMSL
b) Eustatic Sea Level

A

a) LMSL

120
Q

What sea level is affected by total amount of water and volume of ocean basins

A

b) Eustatic Sea Level

121
Q

Define: Eustatic Sea Level

A

= mean global sea level
- across the globe
-affected by the total amount of water and volume of ocean basins

122
Q

What would happen if there is low Eustatic Sea level?

A

= erosion from continents deposited at the margin

123
Q

What would happen if there were high Eustatic sea levels?

A

= erosion inland deposits in the continental shelf

124
Q

The Cretaceous sea level is estimated to range from 100-300m above modern levels.

What are the 5 reasons that cause this uncertainty?

A
  1. decreased volume of ocean basins

1a) decreased mid ocean ridge forming = slow spreading –> larger basin = deeper ocean = lower sea level
1b) fast sea floor spreading –> magma spreads faster + faster subduction = fat profile = higher sea level

  1. collision of continent effects
    - eustatic sea level drops when the basin is bigger (collision = uplift in a plateau and a downfall (aka the root)
  2. transfer of continental sediments
    = fan: river dumping sediments
  3. water stored in ice sheets:
    - hard to find the exact amount
    -antarctic ice can result in a 66m sea level rise (but can decrease as ice has a higher volume than H2O)
  4. thermal expansion of sea water
    - water expands when warmed
    But, water has cooled to 5-15 deg C in the last 100M years = 7m drop in sea level
125
Q

What would a decreased mid ocean ridge forming change sea level?

A

decreased mid ocean ridge forming = slow spreading –> larger basin = deeper ocean = lower sea level

126
Q

How would fast sea floor spreading change sea level?

A

fast sea floor spreading –> magma spreads faster + faster subduction = fat profile = higher sea level

127
Q

If these ice objects melted, how much sea level rise can we expect?

  1. Antarctica Ice
  2. Greenland Ice sheet
  3. Alpine Glaciers
A
  1. Antarctica Ice = 66m
  2. Greenland Ice sheet = 6m
  3. Alpine Glaciers = 1m
128
Q

What are the 5 Uncertainties of sea level change complicated by?

A
  1. Weight of water depresses ocean floor
  2. Continentental margins rise and fall
  3. Shape of Earth (Geoid)
    - has changed
  4. Gravitational Variations
129
Q

What ended the Cretaceous period?

A

= a meterorite landing in the Upperton Peninsula

130
Q

What did the meterorite landing in the Upperton Peninsula result in? (Hint: 3 stages)

A
  1. Immediate warming
    - shockwaves flattened everything around it
    - seismic wave = 10^11
  2. Cooling
    - soot blocked light = global cooling effect
  3. Warming
    - Increase CO2 from wildfires –> warming
131
Q

What is the Paleocene-eocene thermal maximum (PETM)?

A

=55Mya the cliamte suddenly warmed even more
-lasted 150K years
-see depletion of 18O in oceans from sediments (= 18O is evaporated)

132
Q

What are 3 evidences of cooling?

A
  1. Growing Glaciers
  2. Southern beech trees growing in antarctica (found fossil wood)
  3. Change in fossil record of leaf shape
    - jagged edge leaves / finely toothed= colder climate
    - smooth = warmer climate
133
Q

What are jagged edge leaves / finely toothed leaves associated with?

A

= colder climate

134
Q

What are the 2 main processes that affect 18O?

A
  1. Ocean temperature
  2. Size of continental ice sheets
    - ice sheets forming = depleted in 18O (ocean = enriched)
    b/c ocean loses 16O, as 18O is stays behind (dense)
135
Q

MIDTERM: Definition: Fractionation

A

= a change in the relative abundance of a stable isotope during a chemical / physical process

Fractionation points: freezing, evap, melting, condensation, infiltration, runoff, taken up by trees (carbon - by leaf stomata)

-water fractionation = driven by temperature

-tropics = less depleted in 18O than in Arctic
because of precipitation recycling / fractionation

136
Q

T/F: Tropics are more depleted in 18O than in the Arctic

A

True: tropics = more depleted in 18O than in Arctic
because of precipitation recycling / fractionation

137
Q

T/F: In colder climates, there will be more 18O in oceans

A

TRUE

138
Q

When ice sheets formed 40My BP, ocean 18O increased from +0.75% to ___%.

a) 2.5%
b) 3.5%
c) 4.5%
d) 5.5%

A

b) 3.5%

139
Q

For shells made of CaCO3, what may happen in warm water?

A

= shells may uptake Mg to make shells instead

140
Q

MIDTERM: What are 3 reasons why the earth is getting colder?

A
  1. Geography (do not believe)
    - continental plates move around
    -disproven by the Polar position hyp
  2. Ocean Gateway Hyp (do not believe)
    =opening and closing of ocean gates changed poleward transport of heat and silt
    –> give opposite predictions

a) Pacific ocean (fresh, high precip) does not mix with Atlantic (large evap –> more salty / dense)
- at Drake’s passage (S. America + Antarctica)
- may resulted in cooling of S. Pole
(but does not significantly change the cliamte outside of antarctica)
-reduce poleward fluxes

b) Closing of Panama
= should’ve resulted in warming
- enhanced poleward fluxes

  1. GHGs
    a) BLAG
    b) Uplift Weathering
141
Q

Explain the Ocean Gateway Hypothesis and why it is disproven.

A

=opening and closing of ocean gates changed poleward transport of heat and silt

a) Pacific ocean (fresh, high precip) does not mix with Atlantic (large evap –> more salty / dense)
- at Drake’s passage (S. America + Antarctica)
- may result in cooling S. Pole
-glaciation coincides with opening of Drake’s passage
(but does not significantly change the cliamte outside of antarctica)
-reduce poleward fluxes

b) Closing of Panama
= should’ve resulted in warming
- enhanced poleward fluxes

Disproven:
= give opposite predictions
Antarctica –> reduce poleward fluxes
Panama –> enhanced poleward fluxes
- neither = cause for glaciation (but important for ocean circulation)

142
Q

Could decreased GHGs by BLAG cause the observed cooling?

A

= can result in early cooling, but predicts recent warming that hasn’t happened
- slow sea floor spreading does not explain cooling

143
Q

What are the 3 Key Assumptions associated with Uplift Weatering as the cause for cooling

A

Assumes: it takes out CO2 from atmosphere and stored into permanent reservoir in ocean as sediments

  1. More high elevation terrain
    - uplift of Tibetan plateau: think CO2 gets stored in ocean basins
    - no evidence of collisions in previous 250Mya
  2. Unusual rates of fragmentation
    a) Physical: transfer of CO2 from dissolved and back into atmosphere
    b) Chemical: 2nd transfer of CO2 = turned into a solute and stored
  3. Fresh sediments weathering quickly
    - than older sediments
144
Q

What cliamte can you expect if Oceans are depleted in 18O

A

= warmer climate (taken out onto land)

145
Q

Why is unusual chemical weathering difficult to measure?

A
  1. dissolved ions come from hydrolysis or dissolution
  2. too many rivers to measure
  3. human land-use complicates modern signal
146
Q

Why is Palea signal more difficult to measure?

A

= exposing fresh sediment –> high chemical weathering
(although there may be no fresh(new) mountains in the headwaters)

GEOG 2210 (3 decks)

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