"So some of mankind could actually survive the next few centuries here and beyond."

 Most people on earth tend to be thinking in the present moment. 

How do I make enough money to feed myself and my family?

How do I get food, shelter, clothing and a roof over my head and maybe a car?

This is basically where most people are on earth. Hand to mouth.

I cannot fault them for this at all.

However, we are now in a place where JUST thinking like this will cause human extinction in this century or the next by a variety of potential causes.

So, unless enough people move in a direction to prevent human extinction, human extinction will occur some time between now and the next several hundred years.

From my present point of view: (and this could change obviously any moment by unexpected actions of one or more of mankind) is that the maximum amount of people on earth left in 2100 AD is under 1 billion people.

What happens to the rest of the people on earth?

Global Climate changes.

IF you have been watching the droughts and the flash flooding in the U.S. , Europe and China you should not be surprised by my statement at all.

And as the atmosphere heats up even more moisture can stay in the atmosphere raining down in flash flooding more than is happening right now and many other effects as well worldwide.

I was there when Yellowstone flooded in June. My wife and I were very lucky to drive out from Old Faithful Lodge area through Gardiner. So, I saw first hand much of the flooding from a location in between Livingston and Gardiner. We drove out the road that washed away completely near Gardiner by the way.

The maximum amount of water carried ever by the Yellowstone River was about 31,000 units per second around the 1990s I believe. The first day we were next to the river nearer to Livingston the water went to 33,600 units per second. But, within the week the amount of water was 87,000 plus units per second so almost 3 times the previous record of all time.

The point of all this is this: "Once you have seen first hand just how extreme things can get lately you aren't ever going to forget it!"