Sigh, I wish I could agree.

What you are describing is the Earth 2100 forecast from the 2010 documentary on ABC. A "longish" gradual depopulation and slide back into a 19th century low-population world.

Five years ago I would have still agreed with this as being the "most likely" scenario. Based on what we can SEE happening to the Climate System, I no longer think this.

Warming HAS ACCELERATED and we are already feeling its effects. It's going to keep getting worse for centuries but we are going to get a MASSIVE spike of warming by 2050.

Hansen is forecasting +3C by 2050, in just 30 years.

I think it will be between +4C and +5C because of all the CO2 dumped into the atmosphere from the BURNING of the Boreal Forests. I think the CO2 level will be between 600ppm and 700ppm by 2050.

We are on the EDGE, "right now".

By the end of 2025 we will know who is right.

I think the human population by 2100 will be under 100 million (60%), under 50 million (25%), under 25 million (10%), under 10 million (5%).

I think your estimate of 1 billion "Post Climate Crisis" survivors in 2100 is OPTIMISTIC. As DIRE as your forecast seems, it is still, IMHO, a FALSE HOPE.

It gives people the impression that they have MORE TIME than they really do. It's the "frogs in a pot" version of COLLAPSE, where the number of frogs gradually goes down as the pot warms up.

It gives an "illusion" of control. By making it seem that it will be possible to "pull through" if you start "gearing down" NOW and creating "local communities" that you can count on as things gradually fall apart.

The gradual collapse you envision is possible only if warming is no greater than +4C by 2100.

If we have +4C of warming by 2050 then Collapse is going to be FAST, ROUGH, and BRUTAL.

When the FOOD starts running out, EVERYWHERE.

The DYING will be ABRUPT and VIOLENT.

We will KNOW for CERTAIN if I'm right, by the end of this year. 2025 at the latest.