[Tervuren]

Looking at the incredibly wide spread of creatures that need wouldn't survive extreme that you find buried all over the world - I'd warrant that the ideal climate is slightly cooler than our hottest regions, and warmer than our coldest. The ideal climate would have little weather differences, as there would be less temperature clashes across the globe.

In my opinion, something "sheilded" the Earth, keeping it much more uniform - when this was broken, we get very localized changing conditions all over the world.