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Climate System > Lec 7 - Greenhouse Gases and Ice > Flashcards

Lec 7 - Greenhouse Gases and Ice Flashcards

1
Q

What two important GHGs are found in ice cores?

A

methane and carbon dioxide

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2
Q

What rhythm is matched by fluctuations in CO2?

A

the 100ky rhythm of ice sheets

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3
Q

How does CO2 interact with ice sheets?

A
  • driver of changes
  • feedback of changes
  • combo of driver and feedback to ice sheets
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4
Q

How do ice sheets form?

A

As snow accumulates, fluffy layers are compressed until ice crystals form, stopping airflow and making a solid sheet

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5
Q

What are the features of the Cryosphere?

A
  • low specific heat
  • high albedo
  • limited moisture/texture
  • polar distribution, highly seasonal
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6
Q

What is the albedo of the Cryosphere?

A

0.6-0.9

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7
Q

What is the ice-albedo feedback?

A

planet warms = ice melts, exposing underlying material = lower surface albedo = more light absorbed at surface = more warming

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8
Q

What are 2 climatic effects of sea ice?

A
  1. cuts of heat flux from warm ocean and cold Arctic atmosphere
  2. in summer, melting ice keeps the surface water cool
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9
Q

What are some traits of the hydrosphere relevant to climate?

A
  • low albedo
  • large heat capacity
  • limited roughness
  • high moisture
  • 70% of surface
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10
Q

What is the structure of the ocean?

A
  • mixed layer at surface (0-50m)
  • deep ocean - colder with depth, less mixing
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11
Q

How can we learn about HOW Carbon has been moved around in the past

A

isotope ratios! Different pathways use different isotopes

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12
Q

What forms of Carbon can we track?

A
  • organic and inorganic
  • ratios of 12C and d13C
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13
Q

What Carbon isotope do plants prefer?

A

C12 (rather than C13)

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14
Q

How do we know that CO2 is related to ice sheets?

A

comparing to climate archives !

ice cores and marine 18O records

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15
Q

During glaciation, where does all the atmospheric carbon go?

A

Carbon reservoirs and transfer!
- Deep ocean!

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16
Q

During interglaciations, what types of C and O are common in the oceans vs land?

A

oceans have less 18O, more 13C

17
Q

During glaciations, what types of C and O are common in the ocean?

A

high 18O, low 13C

18
Q

In what 3 ways does Carbon get into the deep ocean during glaciation?

A
  • changes to solubility with temperature (cold water = bigger C reservoir capacity)
  • Biological transfer (carbon pump – more photosynthesis = more downward movement of C)
  • changes in deep water circulation
19
Q

What is the biological transfer of Carbon into the oceans (carbon Pump)?

A

plankton photosynthesizing and dying = trapping Carbon in deep ocean
- if organic carbon is oxidised in the ocean into gas again, it can be upwelled

20
Q

How do changes in deep water circulation affect C reservoirs during glaciation?

A
  • controls how deep carbon can be pumped into the ocean
  • water during last glacial max didn’t go as deep as it does today
21
Q

What was the last glacial max like?

A
  • 21kya
  • ice sheets 2km high over NA
  • global sea level 110-125m lower
  • icy, cold, dry
  • more southern tundra systems
22
Q

What 3 ice sheets covered NA 21kya?

A
  • Cordilleran
  • Laurentide
  • Greenland
23
Q

What evidence do we have for the most recent glaciation?

A
  • Global Climate Models
  • Geologic evidence (bedrock rebound)
  • sediment records (sediment size, glacial dirt)
  • pollen (climatic preferences)
24
Q

What do sediment records tell us about the most recent glacial max?

A
  • evidence of glaciers due to formation left behind (moraines, eskers, silt, boulders)
  • sediment records carried by wind (more fine dust than interglacial layers!)
25
Q

What are some examples of pollen habitat preferences?

A
  • prairie grasses/herbs prefer dry, open areas
  • spruce pollen is more abundant in cool/north areas compared to oak
26
Q

What regions were most drastically affected by glaciation?

A
  • areas closest to ice
  • ex North Atlantic (colder, more icce)
  • American Pacific Northwest was cooler and drier, but Southwest was wetter due to jetstream placement
27
Q

What are jet streams?

A

relatively narrow bands of strong wind in the atmosphere
- blows west to east
- follows parallel to temperature boundary

28
Q

During the last glacial max, what were areas far from ice sheets like?

A
  • cooler temperatures (even if no ice)
  • drier
  • lower sea level
  • tropics cooler to unknown extent
29
Q

Why don’t we know how much cooler the tropics were during the last glacial max?

A
  • too far from ice sheets to be affected by ice
  • BUT same insolation as today!
  • GHGs would have caused the cooling, but unclear how much

Climate System (11 decks)

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