CO2 overload in blood suggests toxic atmosphere within 50 years
doi.org
doi.org
There's an awful lot of distance from "can" and "potential" to "toxic".
You also still failed to articulate your argument.
I don't think you want to make this about intelligence.
That said, the authors note that many people regularly do indeed experience long periods of higher CO2 levels, and that this may in part explain the HCO3− blood level trend they're seeing and has to be taken into consideration.
They also note "more recent studies of humans and animals have shown harmful effects of CO2 exposure at [1000 to 3000 ppm CO2], such as changes in heart rate, kidney calcification, oxidative stress, neural damage and inflammation".
The first 440 ppm you’ll get for free. This used to be lower and has risen steeply in the last 100 years and continues to do so.
See the historical graph at https://www.co2levels.org/
Hypercapnia
My personal experience is that when the CO2 levels hit over 1200 in a room, it feels more cozy like a bar or crowded place. With all the up and downsides. Would hate to live in a world where this fog is a constant, as it impedes thinking.
Sounds great, at this point doesn't really seem to be anything I can do as an individual except enjoy the ride, because it's now a race to see whether swarms of killer AI robots do us in, the global economy collapses, the ocean currents fail, and if none of those happen the air will end up killing us all anyway.
Sounds like I might as well try and enjoy it while it lasts. Cheers!
key phrase being "There's a big difference between seeing high concentrations of carbon dioxide as indicative of poor ventilation and seeing high concentrations of carbon dioxide itself as detrimental to cognitive function."
When you click through the actual title is: Carbon dioxide overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years
But if you read that abstract, it's about diagnosing blood diseases, and suggests based on surveys of different studies of current people's blood levels that levels above 30mEq/L be flagged as out of normal. It doesn't discuss harms or outcomes.
So even "potentially toxic" seems baseless.
To add: desertification and more or less removing the support systems for modern population levels can easily happen with what's going on. But the oceans won't boil first. Everything else will die first.
That said, we're more likely looking at more of a prehistoric scenario, near as I can suss, which would be more like, 'most high-metabolism creatures can't hack it, but at least you get some really cool massive dragonflies!'. This is emphatically a place we've been before, and, given all the prehistoric carbon now in every breath, a place we will likely be seeing again, and soon.
I'm very sorry about your planet and you have my condolences.