Humans are extremely adaptable, for example there's people who work in extreme conditions underwater, what would be considered absolutely unbearable and torture is normal. More information on saturation diving: https://www.youtube.com/watch?v=HfiHc_rh4EY

We're already slowly adapting to higher CO2 levels by sitting mostly indoors that have elevated CO2 from 500 to 800 with ranges up to 1500 (taken from my measurements at home).

Claiming that it would be toxic doesn't pass the most basic checks that humanity experience already.

There's probably a lot of genetic variation. For some it could be detrimental in 50 years, for others not so much. And for some swath in the middle it could be less than ideal.

> We're already slowly adapting to higher CO2 levels by sitting mostly indoors that have elevated CO2 from 500 to 800 with ranges up to 1500 (taken from my measurements at home).

But won't that 1500 be even higher indoors as CO2 in the atmosphere increases?

Just because they do it doesn't make such short run adaptations healthy or sustainable.

Huh. Are you denying the upper safe level of serum bicarbonate? Just because we can tolerate 800 ppm of CO2 doesn't mean we can keep pushing it forever; there is clearly a limit. I suggest actually reading the paper.

Diving is not a 24x7 activity, and so it doesn't relate.