Question: "What caused it to be warmer then than it is now?"  Context: "During the Eocene (56 million years ago - 33.9 million years ago), the continents continued to drift toward their present positions. At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the world and keeping global temperatures high. But when Australia split from the southern continent around 45 Ma, the warm equatorial currents were deflected away from Antarctica, and an isolated cold water channel developed between the two continents. The Antarctic region cooled down, and the ocean surrounding Antarctica began to freeze, sending cold water and ice floes north, reinforcing the cooling. The present pattern of ice ages began about 40 million years ago.[citation needed]"  Answer:
The answer to this question is:
warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the world