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14 Cards in this Set
- Front
- Back
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Who first proposed a link between insolation and ice coverage and roughly when? |
Croll, 18th century |
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What is the yardstick for glacial movement and how is it defined? |
Equilibrium point - where ablation equals accumulation |
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What is Milankovitch's hypothesis? |
Only summer insolation determines glacial advance/regression |
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What are the three Miankovitch cycles, their rough time periods and, where possible, their maximum/minimum values? |
1. Obliquity - 22.1° to 24.5°, 41Ka (currently 23.5°) 2. Eccentricity - 0 to 0.06, 100-400Ka (currently 0.017) 3. Precession - solstice aphelion to perihelion, 25.7Ka (currently aphelion) |
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What is the overall change in insolation due to eccentricity changes? |
0.5W/m2 |
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What is the result of a summer solstice at the aphelion? |
Cooler summers and warmer winters in the northern hemisphere. |
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What is the interaction between eccentricity and precession? |
Eccentricity modulates the effects of precession. Low eccentricity results in little effect of changing precession. |
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What are the three ideal situations for glaciation? |
1. Low tilt 2. High eccentricity 3. Solstice at aphelion |
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What was Milankovitch's big hypothesis? |
The incoming solar radiation at 65°N is the principle forcer of glacial-interglacial switches. |
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Which study vindicated this? |
Hays et al, 1976 |
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What are there three challenges to Milankovitch's hypothesis? |
1. 100-kyr problem 2. Middle Pleistocene Transition (MPT) 3. Stage 11 problem |
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Explain the 100kyr problem. How is it resolved? |
Why, if the forcing due to Milankovitch cycles is so weak (around 0.5W/m2) do they result in such huge changes? Must be climatic effects involved too. |
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Ditto for the MPT |
Why did the glacial period shift form 41kyr to 100kyr in the middle-pleistocene without a change in orbit? Change in subglacial conditions - exposure of precambrian bedrock - higher friction substrate causing thicker ice sheets (Clark et al, 2006) |
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And finally the Stage 11 problem |
Why, if climate forcing was so weak on a 400kyr cycle, did termination 5 result in a huge deglaciation? Must be due to climate systems we don't fully understand. |
