Ice Age Dynamics Hypothesis

(Discussion Waterloo U February17, 2011)
The opportunity to review and discuss the Ice Age Hypothesis was much appreciated. The validity of the hypothesis which addresses only the temperature cycles in the last million years rests on a number of assumptions that need further checking.
Initiation of the cooling trend at the peak of the warming trend

1.     Proposition: The Ice Age is initiated by excessive fresh water dilution of the Arctic Ocean and far North Atlantic preventing formation of the dense (cold, salt) water thought to derive the Ocean conveyor.
Question: Does warming of the Tropical Ocean drive result in a sufficient increase in precipitation into the Arctic region generate a flow off surface fresh water off Greenland sufficient to stop the sinking of cold dense water thought to drive the Ocean Conveyor?

2.     Proposition: The major increase in precipitation in the Arctic reverses the flow through the Bering Strait eliminating a source of sensible heat into the Arctic.
Question: What is responsible for the flow of water through the Bering Strait into the Arctic Ocean and how does this affect the Arctic heat balance?

3.     Proposition: The Gulf Stream without the current induced by the sinking of cold dense water is no longer drawn northward and follows a more conventional surface gyre circulation at lower latitude.
Question: Is the sinking of the cold dense water off Greenland responsible diverting the Gulf Stream into the Arctic? 

4.     Proposition: The loss of the sensible heat of the Gulf Stream and the flow through the Bering Strait results in cooling of the Arctic Ocean.  This factor coupled with the continued high regional precipitation induced by the still very warm tropical ocean greatly increases the quantity and seasonal persistence of snow in the region amount, the increased albedo reinforcing the cooling effect. 
Question: Is the Gulf Stream when not drawn into the Arctic region by sinking of the cold dense water driven entirely by the action of the Westerly winds or does thermal expansion of water by solar heating in the Gulf of Mexico contribute by raising the water elevation in that region providing a continually regenerated hydraulic head that must flow somewhere?

5.     Proposition: The closing of the Isthmus of Panama 3 million years ago eliminated leakage of warm Gulf of Mexico water into the Pacific Ocean increasing the flow of warm water into the North Atlantic.
Question: The Ice Age cycle chart shows an immediate response coincident with the closing of Panama but if linked why is it only in the last million years that the cycle frequency changed from 40,000 years to 120,000 years coupled with a doubling of the magnitude of the cooling.

6.     Proposition: Matichenkov orbital cycles do not correlate well with Ice Age cycles and while they may provide a ‘nudge’ marginally influencing the cycles, terrestrial influences are dominant.
Question: What does a statistical correlation show?

Process Postulated for Termination of the Ice Age

1.     Proposition: Water evaporated in the tropics is transferred to the Arctic (and Antarctic) where it is fixed as ice, the tropical surface water thereby increases in salinity  and when carried poleward by the ocean gyres it cools and intermittently sinks into the deep ocean water this sinking being counter-balanced by rising deep water elsewhere The magnitude and persistence of this effect increases as the sea level Falls, temperatures cool and the salt content of the ocean surface increases eventually reaching a critical level where circulation can be sustained and sufficient nutrients and carbon dioxide is released the 100,000 year accumulation to sustain warming trend. 
Question: Do sediments or deep ocean analysis provide any evidence of such a process occurring?

2.     Proposition: The atmospheric concentration of CO2 decreases over the 100,000 year cooling period of the Ice Age and there is a reduction in the inventory of terrestrial biomass.
Question: Where and how is this CO2 stored?

3.     Proposition: In the postulated that in the absence of deep water circulation during most of the cooling period a small proportion of the biological mass in the surface water settles into the deep water and is decomposed by bacterial action liberating nutrients and building up a high CO2 concentration in the bottom water that is partially and periodically released due the overturning of the ocean initiated by sinking cold salt surface masses delivered to cold regions of the ocean by the ocean gyres.
Question: Where else could the carbon be stored?

4.     Proposition: Renewed deep water circulation at the end of the cooling cycle leads to release of CO2 and nutrients that encourage an extensive phytoplankton bloom reinforcing the warming effect of additional CO2.
Query: How can this effect be substantiated?