In this show they are claiming that severe climate change happened within a lifetime. Maybe a single drought, but general climate change can't be resolved to that level a million years ago. That led me to search for some science.
Two-legged ape-like things have been scampering around the Earth for 8 million years. Like the show says, if you put them all into one movie, you'd have the Hobbit. Probably not much conversation, though.
On a scale that large we've had some pretty severe climate change. That's because we're talking about massive plate tectonics movement. This reference was good.
This is a really cool graph, wish I had one! The warm and cold zones synch exactly with the Wilson Cycles, which are the opening and closing of the continents. As I've always said, when the continents are all schmooshed together big things happen that make our current situation happy. That's why I've always voted for low carbon sensitivity because the past would have completely baked us. During warm periods giant reptiles rule, and in the cold it's the time for giant mammals. It's all a matter of how the animals handle heat.
So, the Arctic ice sheets nailed themselves in place 50 million years ago, about the time T-rex said good-bye. No meteor required. We get cold because the deep sediments stop baking and the ocean currents become efficient heat pipes, just like the cooler on your processor.
Now we are into this bounce, but this started millions of years ago. I've told you already, the bounce is determined by isostatic rebound. It's this mess that messed with humanids.
Note that we only get ice sheets up in the North. Can't do too much more to Antarctica. The whole trade winds band tightens up. The oceanic heat pipes dry up. All of this knocked out the weaker two-legs, and gave rise to huge migrations, where you had to have some brains. And you had to survive.
Of course, none of this can compare to the certain doom that we dumb humans are facing...blah.... blah. I'm going up north soon to go cottaging at 40 below. Now, that's survival!