The only time hospitable to human life in last 100,000 years is the last 10,000 years

There was ice over most of earth until 12,000 years ago for the previous 100,000 years. So, even in recent history the only time mankind could grow and develop civilizations has been the last 10,000 years. So, maybe the best way to put this is most of the time the Earth is not habitable by human civilizations. That is not to say that "No one could survive" it just means in the last 100,000 years (previous to 12,000 years ago) nothing beyond small tribes of hunter gatherers likely could survive.

So, after looking at this our seeming assumption that life should be the way it has been in the 20th century is erroneous if you look at the ice during the last 100,000 years before the last 12,000 years. So, it appears most of the time here on earth it is either too hot or too cold for civilizations to develop past hunter gatherer tribes. This is the "normal" on Earth and not what we have experienced the past several hundred years here on earth.

IF it is either too cold or too hot or too windy (or all three in succession to grow food) then civilizations cannot or could not develop no matter how long mankind actually has been on earth except during a cycle like we presently have had for around 10,000 to 12,000 years now.

So, the most predictable thing about Earth is that temperatures vary wildly over time. So, I think the assumption that weather should be any one thing is erroneous. The systems of climates the last 2.6 million years have been all over the place. Just look at the little Ice Age from around 1300 to 1800 off and on. And now, temperatures could be spiking from humans or a combination of humans and just natural Earth cycles. It's really hard to say after looking at the last 112,000 years and further back.