Southern pole sea ice expansion drives ice ages , along with orbital effects.
“According to Lee’s models, it has to do with the fact that the planet has been generally cooler over the past million years than it was prior to that. The models show that, when the Earth was generally warmer than today, precession-related sea ice expansion in the Southern Hemisphere is less likely to occur. That allows the obliquity cycle to dominate the global temperature signature. After a million years ago, when Earth became a bit cooler on average, the obliquity signal starts to take a back seat to the precession/eccentricity signal.”
Southern pole sea ice expansion drives ice ages , along with orbital effects.
“According to Lee’s models, it has to do with the fact that the planet has been generally cooler over the past million years than it was prior to that. The models show that, when the Earth was generally warmer than today, precession-related sea ice expansion in the Southern Hemisphere is less likely to occur. That allows the obliquity cycle to dominate the global temperature signature. After a million years ago, when Earth became a bit cooler on average, the obliquity signal starts to take a back seat to the precession/eccentricity signal.”
https://watchers.news/2017/01/26/orbit-variations-ice-age-study/
“Hemispheric sea ice distribution sets the glacial tempo”—Jung-Eun Lee, Aaron Shen, Baylor Fox-Kemper, Yi Ming—Geophysical Research Letters (AGU) - Accepted January 7, 2017 - DOI: 10.1002/2016GL071307