During the past million years Polar Ice Cycles regulated temperature by snowing more during warm times and adding ice and albedo and snowing less during cold times and letting ice and albedo reduce. There is 800 thousand years of data from Ice Antarctic cores on the previous chart. The oldest time is on the bottom on the right and the more recent ten thousand years is on the top on the left.
The last 800 thousand years was very cold most of the time, with some major warm periods in between the longer, very cold, major ice ages. The warm periods occurred when Ice Extent was low and oceans were warm and Polar Sea Ice was thawed and much snowfall replenished the ice volume.
The long cold periods occurred when the Ice Extent was large and oceans were cold and the Polar Oceans were Frozen and the frozen oceans did not provide enough snowfall to maintain ice volume. The ice sheets melted during the long cold periods and when the ice sheets became thin enough, ice retreated and allowed Earth to warm again.
Temperature in this time period is being regulated by something different that was not around during the earlier time without Polar Ice.