Greenland basin of attraction

Greenland Basin of Attraction

During a glacial circumstances favor stacking ice in the Greenland basin of attraction. During an inter glacial the opposite occurs. Also consider what the massive weight of the ice does to the shape of the basin over time. Slope or curve changes of the basin probably help determine when a transition occurs. Over time the Greenland basin will tend to sink during a Glacial under the added weight. Ice at lower elevations may more easily melt and sea water may undermine the ice if the land is pushed down far enough.

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5 thoughts on “Greenland basin of attraction

  1. I was impressed with your comments on Dr. Curry’s blog. As a result I am going to investigate ocean currents correlations with polar ice melts.

    Realizing that a correlation has been made with the TH Conveyor interruption in the NH and the YD event, I think that it’s full significance is unappreciated, along with the effect of the PDO on global mean temp. This all point to ocean currents as the gorilla of climate change. The mechanism of raising GMT by spreading out surface heat is demonstrated in M-cycle correlation to paleo GMT reconstructions. After all, M-cycles are just means for spreading heat in more even distribution across the globe. There is no actual change in the Sun’s radiance or annual proximity in any of the M-cycles. The fact that GMT is raised in more even distributions of surface heat means that the opposite is also true, that the globe is overall colder when heat is concentrated. If this is true then physics would demand an explanation by either the concentration causing an increase in albedo or heat loss by penetration of increased depth into the oceans, or both. Albedo perhaps is also increased by higher density cloud formation in the equatorial regions (the areas also of highest insolation).

    Albedo is clearly increased some by increased polar ice. We also know that this is self-reinforcing. More cooling causes more ice which causes more cooling. And the opposite is true; lakes in the ice catch more heat, more receded glaciers make more heat absorbing surfaces behind, etc… Although this makes the dynamic sensitive it does not make it chaotic. With a steady sun and no variance beyond night and day and seasons there is no engine for chaos. If M-cycles were the only mode of variation in heat distribution we would see only a gradual glaciation cycles spanning thousands of years in sink with M-cylces.

    Enter ocean currents… Ocean currents are powerful and unpredictable. The fact that a warmed surface’s decrease in density creates a thermal barrier to convection means that the ocean is driven by chaotic wind, river flows and Earth rotation, all weak forces. The dominant ocean current we know is driven by polar ice melt, alternating at each pole’s summer, a chaotic pulse motor.

    Now, putting ice caps together with ocean currents means that the more extreme the seasons are the more extreme the ice melts and the greater power behind the TH Conveyor. This means more heat distribution, which means more ice melt which means more currents. We have a run-away de-glaciation. Any event that interrupts the ice melt for more than a year could cease the TH conveyor and lead to a reverse run-away cooling, which progressively weakens the current and heat distribution. The closer the Earth is to an M-cycle insolation minimum the lessor the event necessary to trigger glaciation since the ocean current is the dominant force at that point keeping the ice caps in check. The opposite is also true, explaining at least the last ice-age’s abrupt ending as Earth was entering a peak distribution of heat through it’s M-cycle.

    • “Now, putting ice caps together with ocean currents means that the more extreme the seasons are the more extreme the ice melts and the greater power behind the TH Conveyor.” Interesting idea about the speed of the melts. Applying this to sea ice, we could have snap freezes in the Fall, trapping heat under the ice for a longer period or longer (more) venting from ocean to atmosphere with a delayed freeze. Something to do with the time sensitivity of the sea ice formation and significant ice out conditions. My question is, does more extreme seasonal temperature variations favor or disfavor ice sheet and sea ice formation?

      • Good question. I think the whole power behind M-cycle warming is their supply of annular variation in insolation and thus providing a pumping mechanism for ocean currents through alternate polar melt. I read today that interruption in the north Atlantic wing of the TH conveyor has been associated multiple paleo-dips, not just the YD. It is speculated that there is an alternate stability track for the TH during glaciation, I guess it would be fair to call it the normal one (seeing that it runs that way 90% of last million years). As Kim posted on JC.com, “I hope the warming is from Gaia, otherwise we are running out of fuel to keep doing the heavy lifting.”

      • I also read confirmation that the TH is extremely sensitive. It is thought to be powered by high density (recently evaporated) cooling surface water as it moves north finding itself both cold and more saline than under-layer and thus falling down. This is why the concern about fresh water melt dilution effecting the system. I believe that simple force of gravity of falling ice run-off and melt is an even more powerful downward force. After all, as it falls through the ocean surface that displacement is a lot more concentrated downward force that a gradual imbalance in salt content.

  2. Draining of the Laurentide Ice Sheet I am thinking short circuited the NA TC down from Greenland to lower Nova Scotia for the YD, due to high melt runoff, to the preferred route. This route was normal during glaciation since it had much more cold water flow than Greenland during Ice Age summers. .

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