Of interest is that fact that 1 million years ago when the article says things began to change is also when the every 100,000 year Ice Age/warming pattern began. That ought to get some study.
I have been for many years now. Geological evidence shows those cycles have been happening much longer than that. Unfortunately we can just recently only go back roughly 2.7 million years with the ice core samples. Whats interesting is that at around 1 million years ago they were more frequent at about every 40k than they are now at about every 124k. The cycle has slowed in frequency over time.
But there are many factors that could have caused this change the article mentions. The equator could have physically been in a different location around earth. The biggest climate influence could have changed which would be the ocean currents. Extraterrestrial events, Volcanic activity, many different things that coincidentally could have happened at the same time, Etc.
Something else interesting is that the earth timeline has been in a cold cycle much more than a warm cycle to the tune of about 85% glacial to 15% interglacial cycles. The cold glacial periods last a lot longer than the relatively short warm interglacial periods. So we had better enjoy it while we can, the interglacial summer is about over. :)