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GEOG 2210 > EXAM > Flashcards

EXAM Flashcards

1
Q

What were the features defining the (most recent) glacial world?

A

=more ice, less gas
1. Continents in ucrrent configurations
2. mountains and plateaus where they are today
3. !!ginormous ice sheets!! (defining feature)
4. less GHGs (CO2 in atmosphere)
- not sure why less CO2 +CH4

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2
Q

Definition: Cold based glacier

A

= on ice (therefore it moves slowly forward)
- ablation occurs by calving

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3
Q

CLIMAP: how big were the ice sheets?
What are the 3 main points of contentions?

A
  1. Did ice sheets reach their max extents at the same time?
    - “did the 3 big ice sheets grow at the same time”
    - Evidence (benthic foraminifera)= yes
  2. How extensive were marine ice sheets?
    - “how big”
    - Not sure
  3. How thick were the ice sheets?
    “ how much CO2 came out of the atmosphere”
    - CLIMAP - predicts ice was thick
    : dry glaciers - less slip, stqay above ablation line = grow taller
  • Current thinking - thinner: looking at how fast it retreated
    : look at isostatic rebound but more extensive
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4
Q

What are “prolific produces of rock debris”?

A

=Glaciers

  • this gives good evidence on the previous glaciers, but looking at the glacier soils and dirt.
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5
Q

What happened with the ice sheets 9K years ago?

A

= they did not grow, even though solar insolation decreases

  • This is because of tilt and precession (the solar forcing doesn’t decrease as fast to cause another galciation)
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6
Q

Why are there no sand loess deposits in Canada?

A

= because it was covered in ice

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7
Q

What are white sands associated with?

A

= glaciation

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8
Q

What can be trapped in ice cores?

A
  • ice bubbles
  • pollen
  • dust
  • Na ions
  • NaCl ions
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9
Q

What are 2 characteristics of Pine plants?

A
  1. prolific produces of pollen
  2. can’t self pollinate: can only with those that are wind borne
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10
Q

T/F: The climate ouside of the ice affected regions were also affected in the N and S hemisphere

A

TRUE

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11
Q

In the southern hemisphere, the cliamte changed NORTH/SOUTH of ice affected regions?

A

SOUTH

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12
Q

How much colder were the tropics? + why does this matter?

A

CLIMAP: says it was 1-2 deg C colder

Why it matters:
- tropics are not directly affected by ice, therefore it must be responding to GHGs
= the change in temperature shows how sensitive is the earth

  • If it was a lot colder,
    = we would be highly sensitive to rise in CO2.
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13
Q

T/F: Terrestrial environments experience small amounts of cooling.

A

FALSE, Large amounts of cooling

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14
Q

LOW LATITUDES in Terrestrial environments experience __ - __ deg C of adiabatic cooling?
+ what type of adiabatic cooling is this?

A

3-4 deg C

assume wet adiabatic lapse rate (if it was dry, it would be 6-10 deg C)

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15
Q

What is the problem with CLIMAP’s estimate of the climate in the tropics?

A

= estimate is too small
- tropical plankton is less sensitive to temperature than to food availability
- small changes in community structure were due to increased food availability

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16
Q

What is the problem of Glacial data’s estimate of the cliamte in the tropics?

A

= estimate is too big
- glaical seas were lower back then
- mountains were higher

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17
Q

What is today’s world climate compared to the cliamte in the tropics?

A

= in the middle
- not as sensitive as terrestrial suggests but more than CLIMAP suggests

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18
Q

What is the Climate sensitivity to GHGs?

A

= approx 1 deg C / 30 ppm

Reasoning:
- tropical cooling was approx 30 deg C
- Atmosphere CO2 was 90ppm lower

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19
Q

Modern CO2 is ___ ppm higher than pre-industrial

A

140ppm

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20
Q

How can you tell when ice sheets melt?

A

= use carbon dating

  • Deglacial processes ended 10K years ago
    (10K years ago: Max tilt, summer coincided with perihelion)

Radio carbon dating in corals
- come from atmosphere + into the mixing layer in the ocean
- deep ocean had older carbon compared to atmosphere

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21
Q

When did max tilt occure at the same time when summer coincided with perihelion?

A

10K years ago

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22
Q

Describe the Deglacial two-step.

A

= suggests complex ice dynamics
- shows the amount of H2O added as a function of time (glaciation)

  1. fast part of glaciation
  2. slow part of clatiation (Younger dryas)
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23
Q

What provides evidence of local melting?

A

=planktic foraminifera in meltwater regions

foraminifera will be 18O depleted when glacial ice melts into the ocean
(b/c glacial ice is highly depleted in 18O)

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24
Q

What are the 5 lines of evidence for younger dryas?

A
  1. pollen archives
  2. atlantic foraminifera
    = pollen from the oceans
  3. temperature proxies (chironomids)
    - shed outside skin
    -sensitive to temp
  4. moraines (glacial readvances)
  5. ice cores
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25
Q

T/F: there was less ice accumulation in the interglacial period and rapid ice accumulation during the younger dryas

A

FALSE,
- rapid ice accumulation in interglacial
- less ice accumulation during younger dryas

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26
Q

What caused the Younger Dryas

A

= the Younger Dryas cooling remains an enigma

Possibility: changes in flow of meltwater
Fresh + Salt water have diff densities = cap –> prevents N atlantic water

Cons:
- still a lot of water coming from the Gulf of Mexico
- no evidence in Arctic, no mass of fresh water coming in at once

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27
Q

Why is the change in flow of meltwater not a plausible explanation for causing the Younger Dryas?

A
  • still a lot of water coming from the Gulf of Mexico
  • no evidence in Arctic, no mass of fresh water coming in at once
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28
Q

Define: Deglacial Climate Feedbacks + give 2 examples

A
  • deglacial climate initated by rising insolation
  • needs positive feedbacks to amplify the signal

2 examples
= ice dynamics could have caused rapid thinning
1. lifting
= sea level will rise, ocean will life up tongue of glacier and glacier may lift and slip into the ocean (as well as calf)
2. glacier grinds bedrock

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29
Q

How are deglacial lakes and floods formed?

A

= ice accumulates mass > depresses underlying bedrock = lakes form at the front of glacier

floods can form after a dam (1 major floor of many small floods)

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30
Q

What are the 4 channeled scablands?

A
  1. V-shape valleys - from rivers
  2. U - shaped valleys - from glaciers
  3. square shaped valleys
  4. ripples
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31
Q

T/F: stronger monsoons are associated with increased solar forcing

A

TRUE

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32
Q

If the wind blows in one way, in what direction is is the mass transport?

A

= the mass transport is 90 deg in the direction of the prevailing winds

–> wind blows in one way, the ocean transport is 90 deg
- brings up deep water and monsoon associated species

33
Q

Geological evidence suggest even stronger monsoons than the theory predicts. Why is this so?

A
  1. stength of monsoons are based on the strength of the winds
    Why? more feedbacks happen in the monsoon system
  2. precipitation recycling by vegetation enhances moisture transport.
    - see max precipitation at 10-15 deg N (with vegetation, there will be more precipitation higher north)
34
Q

At the LGM, what regulated high latitude cliamtes?

A

=ice sheets
- as ice sheets melt, isolation dominates

35
Q

What changes occured after ice sheets melted after the LGM in high latitudes

A
  1. vegetation migrated N following glacial retreat
  2. diff species migrated at diff rates in diff directions
36
Q

Define the “No Analog Problem”

A
  1. postglacial vegetation assemblages exist nowhere today:
    eg. midwestern forests (spruce, ash, etc)
  2. unique climate
    there is no similar cliamte regime that exists today
  3. unique vegetation history
    = vegetation responding individualistically to HUGE changes in climate
37
Q

Describe the Hypsithermal Era
+ provide 2 potential causes

A

=mid holocene temperatures were the highest in the last 100K years

  • no ice, 5% brighter

Causes:
1. sea ice feedbacks
= high latitude warming amplified by albedo changes

  1. role of vegetation - vegetation feedbacks
    = high latitudes amplied by albedo changes
    - vegetation responds to warmer temperatures
38
Q

Why does vegetation matter for monsoons?

A

=plants transpire and then wind blows it more inland = monsoons occur further inland

39
Q

T/F: After the Hypsithermal era, there was a period of renewed warming

A

FALSE, renewed cooling

40
Q

Describe the renewed cooling period, following the hypsithermal era

A

= isolation has decreased 5%
- ice cores from arctic
- marine sediment cores in N. Atlantic
- glacial advances in high arctic
- treeline retreat: further north / further upslope

41
Q

Definition: Millenial Oscillations

A

= range from 1-9K years
- strongest / mainly during glacial periods
- is quasi-cyclical
-out of phase between hemispheres
-decreases in 18O are matched by increases in dust
- no obvious cause

2 parts:
1. Stadials: the cold part of the cycles
2. the warm(er) phases in between the stadials

42
Q

With millenial oscillations, decreases in 18O are matched by increases in dust. Why is this important

A

There is more -ve oxygen in oceans when its colder, and less when its warmer

43
Q

How can we get information on the N atlantic oscillations?

A

= look at sedmient drift
- have high resolution
- accumulation rates are 10x higher than most ocean records

44
Q

Why are most ocean records not sufficiently resolved?

A
  • accumulation rates 1-2cm / K years
  • bioturbulation in top 5-10 cm
45
Q

Why is detecting and dating elsewhere hard?

A

= not easy to do
- climate resolution too slow
- dating inaccuracies are approx 1K years

46
Q

T/F: there is little to no evidence for interglacial oscillations

A

TRUE

47
Q

What are the 5 potential causes of Millenial Oscillations?

A
  1. Stochastic resonance
    = red noise w/ a weak preference for millenial variability
  2. Solar variability
    - stronger sun = less production of radiocarbon
    - cycles: 420 years or 2100 year
  3. Ice Sheet Instability
    = ice dynamics along ocean margins impact a- 1K year signal
    - ice sheets vary on diff continents

3a. Build up ice
= glacier stalls out, geothermal heat will melt glacial ice = calving + ice retreat

3b. sea level rise: positive feedback loop
- sea level will rise when ice melts from being calved off in the ocean
- short / long scale sea level change

  1. GHG forcing
    - insufficient data
  2. Ocean Heat Transport
    - only affects coastal regions
48
Q

Why are millenial oscillations important to understand?

A

= because they are much faster than orbital changes

49
Q

Is the current warming natural?

A

= probably not
- unpredictable
- only occured during ice ages

50
Q

EXAM: Describe the Savannah hyp

A

= African forests dried out to form patchy savannas. This influenced humans to evolve and stand to look around

51
Q

EXAM: Describe the variability Selection Hyp

A

= rapid evolution occured in response to a changing environment
- early pleistocene: 41K time scale glaciers
- late pleistocene: 100K time scale glaciers
(alternate from dry to wet conditions)

therefore, needed to adapt under those variable conditions

52
Q

What conclusion can be drawn from the Savannah Hyp and Variability Selection Hyp? What is a challenge of this?

A

= evidence supports a transition from forested to savanna conditions at the point of rapid evolution

Challenge:
- can’t tell if there is a slow evolution and then a rapid selection (not enought evidence)

53
Q

What are the 2 suggestions of why farming started at the end of the last glaciation?

A
  1. Warmer wetter climate made it possible
  2. The younger dryas made it necessary
    - agriculture is a solution (when it got cold and dry)
54
Q

What can we look at to discover how humans had a profound impact on land cover

A

= pollen records

55
Q

Describe the OverKill Hyp

A

= humans had the tools and experience to kill more animals to the point of extinction

= humans changed the climate so much to drive large mammals to extinction
“early agriculture had an impact on GHGs and climate”

56
Q

Why is the last glaciation event unlike every other glaciation event?

A

= CO2 and CH4 started to rise after the last glaciation event, whereas the other glaciation events saw that they went lower

57
Q

Describe the Early Anthropogenic Hyp.

A

=deforestation associated with early farming efforts released CO2
+ rice paddies and livestock released CH4
(half life of CH4 is short)

58
Q

T/F: the Half life of CH4 is short

A

TRUE, it is 25 years

59
Q

How can humnas raise CO2 by a significant amount?

A

= they can’t. They need unknown feedbacks to amplify

60
Q

Describe the Medieval Warming Period

A

= climate warmed from 1000-1300 CE
- mostly focused in N Atlantic
(europe got warmer)
- globally asyncronous (suggests some warming in certain places)

61
Q

T/F: THe Medival Warming period was globally synchronous

A

FALSE, globally asynchronous

62
Q

What happened 100 years after the Medieval Warming Period?

A

The Little Ice Age

63
Q

Describe the Little Ice Age

A

= climate cooled from 1400-1900 CE
- widespread evidence in the N Hemisphere

areas covered in ice now have vegetation in the present day

64
Q

How can we use Map Lichen to understand if an area is glaciated?

A
  • grows radially - can date using their diameter
    = bigger diameter = suggests its not glaciated
  • get scraped off by ice / killed from snow
65
Q

What are the 3 lines of evidence that the recent climate warming was unprecidented and there was a medieval warming period

A
  1. Quelccaya ice cap peru
    in 1975: 1500 years of annually recovered data
    1991: unprecedented ice melt (only melt water)
    - the melting lost the annual signal
  2. Tree Rings
  3. Corals
    after 1850, it gets warmer
66
Q

What are the 5 Causes of Preindustrial Climate Changes? + what is the best answer

A

Best answer: All contribute (except orbital forcing)

  1. Orbital forcing
    - too slow
    - could cause about half of observed cooling before the Medieval Warming Period
    - could also contributed to anomalous warming during the Medieval Warming Period
  2. Bipolar seesaw
    - Dansgaard-Oeschger oscillations could enhance orbital forcing (only in glacial periods)
    - could also contributed to anomalous warming during the Medieval Warming Period
  3. solar variability
    - sunspot variability could affect the climate

Direct Measurement: satellites measure 0.11% variability in solar output

Indirect Measreuments: look at # of sunspots
- max height of ice extent ( in ice age) = lowerest number of sunspots
- end of ice age = lots of sun spots

  1. Volcanoes
    - volcanic emissions exert a strong cooling affect

EXAM: if it is the extratropics, it only affects the hemisphere, what is the volcano affect in different positions on earth?
- Eruptions > 25 deg N/S, hemispheric impact is only in THAT hemsiphere
- tropical eruptions = global impact

  1. GHGs
    - natural (solar + volcanic)
    - people (land cover change)
    - black death = small pop density = less need for land cover = less need for trees to take up CO2
67
Q

EXAM: At what location do volcanos have a hemispheric impact (only in that hemispehre)

A

When Eruptions are > than 25 deg N/S

68
Q

EXAM: At what location do volcanos have a global impact

A

= in the tropics

69
Q

Describe El Nino (southern Oscillation)

A

= wind blows from east to west, warms up
- every now and then, the circulation cell breaks down (eg. water sloshes back)
- specific to the pacific - because of the size of the pacific ENSO

70
Q

T/F: Pacific decadal oscillations spatially look at el nina

A

FALSE, El nino

71
Q

Global T has risen __ deg C since 1850

A

1 deg C

72
Q

The Global T has risen 1 deg C since 1850. How much of that is natural? GIve potential sources

A

Biggest impact:

  1. Rising CO2
    - fron land clearing
    - from burning fossil fuels (smoking gun)
  2. Rising Methane
    - cows
    - rice patties
  3. Halo-carbon
    - CFCs: deplete ozone
73
Q

Definiton: The Smoking Gun

A

= we know burning fossil fuels are really old because it has no C14 (transitioned back into 14N)
- all carbon in fossil fuels are depleted in C13 (high C12:C13 ratio)

74
Q

Definition: Climate Sensitivity
+ what aare the 2 ways to estimate cliamte sensitivity

A

= a measure of how responsive the surface temp of the earth is to a chnage radiative forcing deg C/ (W/m2)

2 methods:
1. GCMs: Climate Model Estimates
- run models of potential scenarios

  1. Paleoclimate estimates
    - look at time where CO2 was high + low
    - don’t know a lot (only 4 data points: LGM, cretaceous, paleocene-eocene thermal maximum (PETM)
75
Q

Why isn’t the earth warmer if the temp rose to 1 deg C +GHG are now 60%?

A

= ignores 2 factors:

  1. Ocean Heat Capacity
    Total warming commitment approx 2 deg C
    = aka if we stopped emitting today, it would still increase by 2 deg C because of the amounts we already emitted.
    - b/c it takes time for the oceans to absorb extra heat and the next location for absorption is the atmosphere
  2. Aerosol Cooling
    - sulphate aerosols have a net cooling affect
    = will offset
76
Q

If the temp rises fast, what does it say about the climate in response to GHGs

A

= that the climate is sensitive to GHGs

77
Q

If the temp rise is natural / gradual, what does it say about the climate?

A

= it is insensitive to GHGs

78
Q

What is the current disequilibrium? What are some fast and slow respondings?

A

= current emission rates are much faster than tectonic/orbital/glacial changes

Fast responding:
- atmosphere
- land surface / vegetation
- upper ocean

Slow responding:
- ice sheets
- deep ocean

79
Q

Why can we not look at the past to run models for climate disequilibrium?

A

= because there is

GEOG 2210 (3 decks)

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