It’s fine to think about and have concern with these questions.

I’ll be the first to admit that I don’t know the answer to your question/ assumption that

1) co2 will continue to increase linearly,

and

2) the complex system that is earth does not have a mechanism to store co2 at greater rates, and

3) humans cannot adapt to life at 5000.

As someone who has not spent his entire life on these topics, this seems like it could be a credible question to explore.

Going to your If/Then statement: if you are claiming crisis the onus is on you to prove this.

Thus far, humans have never been safer from climate.

Using the term crisis today is counter-productive in many ways.