> Most of the earths history didn't even have ice caps.

Most of Earth's history also didn't have humans. Or animals, even.

Fortunately over the course of Earth's history, the planet managed to develop a climate that was favourable to human life, and now we've gone and destabilised that.

It's not that Earth is immediately inhospitable to human life, but it is disrupting everything that we thought that we could count on. Countries that developed around an abundance of water suddenly have droughts. Other countries get way more water than they're used to. Or it gets more extreme: droughts followed by massive floods.