During mid Pleistocene, somewhere between 1.2 million years ago and 700,000 years ago, glacial cycles are said to have changed from every 41,000 years to a cycle of 100,000 years. We are informed the reason why this happened is unclear. One theory is that the growth of the Atlantic ice sheet – and an expansion of sea ice around the Antarctic, triggered ice expansion in the northern hemisphere. Somehow. One thing left to the side is that somewhere between 1.2 and 0.7 million years ago there waas a reversal of earth’s magnetic field. A super excursion event. This was a reversal that did not swing back. It was permanent, it is thought – unlke Laschamp.
The press release goes on to say the latest study contributes to our understanding of what causes ice ages. You might ponder that one. Funnily enough, during the last so called 100,000 year episode the earth was quite warm and bountiful for a large part of the time. There were very cold episodes, at the end of the last interglacial, then around 73,000 years ago, and again around 40,000 and 33,000 years ago, coinciding with Laschamp, and the onset of the Late Glacial Maximum etc. Not exactly conforming to the 100,000 year model.