There was no antarctic ice sheet 3-4M years ago.

Prior global warming periods are attributed to obviously natural processes. Curious that current warming MUST BE OUR FAULT when past episodes (of thus far unexplained origin) were far more dramatic melting antarctic ice sheets completely.

NZ Herald

[...]Twelve million years ago, at the bottom of the core, it was cold, says Naish. The bottom looks pretty similar to the top, which represents a million or so years.

The middle of the core, however, is much more dynamic and variable. Scientists can see periods where the ice sheet and ice shelf disappeared, around three to four million years ago[...]