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Javier
#1
From HERE


Quote:During this period the climatic periodicity transitioned from 41,000 to 100,000 years between ice ages. Why this change happened is the mystery scientists want to resolve

There is no mystery. There is no transition. They are just not looking properly at the data. The world has been cooling relentlessly since the Oligocene. Orbital changes have been responsible for the alternation of warm (interstadials or interglacials) and cold (stadials or glacials) periods by increasing or decreasing high latitude insolation. Interstadials took place every obliquity oscillation (41 ky), but as the planet cooled the amount of extrapolar ice during glacials grew to a point when obliquity alone was not enough to melt the ice. Then an obliquity oscillation was skipped and the time between two interglacials became 82 ky. At times of high eccentricity the planet returns briefly to a 41 ky period (MIS7 and MIS15 at 200 and 600 ka). The result is that interglacials take place with an average periodicity of 73 ky. That’s why there are 11 interglacials in the past 800 ky. If it was a 100 ky periodicity there should be only 8, but there are 11. During the past glacial two obliquity oscillations were skipped. That glacial lasted then 123 ky. The reason was that the second obliquity oscillation did not have the correct orbital configuration to produce an interglacial. Eccentricity was low and the peaks in obliquity and precession were not properly aligned.

The planet is so cold that it has become tricky to escape glaciation, but that is not a mystery. It is all in the data. We can predict that the next interglacial will take place in about 70 kyr. Once the Holocene is over we should have over 60,000 years of ice age.


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