Earth’s Orbit and Ice Sheets

2 June 2022
Astronomy

At https://phys.org/news/2022-05-theoretical-accounts-sun-rotation-magnetic.html … some new evidence on the sun, its rotation, and its generation of magnetic fields. A new model has been created, mainly to explain the chemical structures.

At https://tallbloke.wordpress.com/2022/05/27/scientists-shine-new-light-on-role-of-earths-orbit-in-the-fate-of-ancient-ice-sheets/ … which is said to solve the 100,000 year problem. The lack of an obvious explanation for the periodicity of the Ice Ages over the last one million years where it is thought the ice sheets come and go at that time scale, mainly as a result of oxygen isotopes of marine algae. Something is clearly wrong, it would seem, as the 41,000 year cycle is the stronger. In fact, they admit the 41,00 year dominates but when we look at 41,000 years ago we find the Laschamp excursion, or reversal of the magnetic field. This is not necessarily anything to do with an Ice Age, which kicked in around 30,000 years ago, if these dates are realistic. The blog is derived from https://phys.org/news/2022-05-scientists-role-earth-orbit-fate.html …  and ultimately is derived from a new study at https://www.science.org/doi/10.1126/science.abm4033

The comments are interesting, especially the input by Ned Nikolov, a PhD. He says the new research delivers more of the same confusion on the topic, on what caused the Ice Ages. He is clearly not onboard with the Milankovitch cycles. See for example https://tallbloke.wordpress.com/2022/01/03/ned-nikolov-dispelling-tghe-milankovitch-myth/ … in which he says eccentricity has only a small effect on global temperatures. The idea is highly exaggerated. Variations in the orbit have a negligible effect, is what he is implying. Also, obliquity, another assumption subsumed in ice sheet advance and retreat calculations, concerns the angle and tilt of the axis relative to the plane of the ecliptic, is poorly understood as it has recently been found that Jupiter also plays a role. See https://iopscience.iop.org/10.5847/1538-3881/ab5365/pdf … In fact, Jupiter, Saturn, Venus, and the Moon, all affect earth’s obliquity. Chinese astronomers were puzzled by this back in AD173. They were measuring earth’s tilt. Obliquity can, and has been, changing abruptly for millennia, causing climatic change -= as well as changes in the precession of the earth’s axis of rotation. Even George Dodwell is mentioned, and a discussion on his theory at Tall Bloke’s talk shop .

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