CLIMATE: L7 + 8 Linking the themes

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  • Created by: Elena
  • Created on: 03-04-14 14:48
Earth's cyclical climate change trends driven by two main external forcing factors:
i) orbital parameters - croll/milankovitch ii) the solar output
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Impacts of incoming radiation are however affected by what?
internal forcing factors (distrib of land and oceans)
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importance of internal forcing functions and fine resolution records - eg ocean. EXPLAIN HEINRICH EVENTS/ ICEBERG ARMADAS
when ice sheets break up at end of glaciation - release pulses of cold water - a fine resolution record
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Give example of the 6 times these heinrich layers have been identified
Detected in N Atlantic sediment cores between 70-14BP. H1 = 14-15 ka BP H2 = 20-21 ka BP H3 = 27-29 ka BP H4 = 35-39 ka BP H5 = 50-54 ka BP H6 = 66-69 ka BP
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Which are older.. ice cores or ocean cores?
ocean cores
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Describe climate's flickering switch
High frequency climate oscillations. 20 interstadials of relatively mild climate during last cold age 80-20kaBP.
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What are daansgard-oeschger events?
show gradual cooling followed by abrupt warming. ASYMMETRIC. Temp changes of 7 degrees.
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How can we match ice core and ocean core records?
Bond cycles. After large warming, the next daansg. oesch. cycle wouldn't be as hot, and the next cooler still. After 3/4 D-O events there would be HUGE WARMING and sequence would then continue.
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So what specifically is a bond cycle?
a cooling cycle 10-15,000 yrs long.
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DO FLICKERING EVENTS INFLUENCE LONG TERM CLIMATE?
yes
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What are the causes of sub milankovitch events
Autovariation and external forcing eg sunspot activity
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What is autovariation?
eg laurentide ice sheet growth and collapse. As calving ends, ice sheet retreats from deep water. Increase in ocean salinity, strengthens thermohaline circulation, more warm water from gulf stream - rise in temps. CLIMATE OUT OF PHASE.
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What are the two causes of this autovariation (what models)
MacAyeal model (internal) and Denton model (external)
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What about sunspot activity? principle.
low sunspot number = low solar magnetic activity. reduction in galactic cosmic rays reaching atmosphere. reduced 14C production.
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Deglaciation was punctured by what event?
the younger dryas. ended abruptly with 7 degrees warming in a few years.
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What was the younger dryas?
an event forced by freshwater outburst from glacial lake agassiz. Meltwater originally routed from misissippi to gulf of mexico. BUT ICE SHEET RETREAT - drained instead into labrador sea. impact on gulf stream. freshwater input shut down NADW
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What about the younger dryas in britain?
grampian highlands, NW highlands, Pennines, snowdonia, lake district: reconstructed based on geomorphological & lithostratigraphical evidence = moraines, drift limits, cored sequences in lake basins.
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Card 2

Front

Impacts of incoming radiation are however affected by what?

Back

internal forcing factors (distrib of land and oceans)

Card 3

Front

importance of internal forcing functions and fine resolution records - eg ocean. EXPLAIN HEINRICH EVENTS/ ICEBERG ARMADAS

Back

Preview of the front of card 3

Card 4

Front

Give example of the 6 times these heinrich layers have been identified

Back

Preview of the front of card 4

Card 5

Front

Which are older.. ice cores or ocean cores?

Back

Preview of the front of card 5
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