And they also vary CO2 levels systematically by geography as well; if that was enough for a detectable effect on IQ, then the lower CO2 levels around Denver should make the rest of us at lower altitudes, such as sea level, look obviously handicapped. If you believe the altitude point refutes effects of oxygen, then it must refute effects of carbon dioxide and nitrogen as well...
Which is part of my original point about implausible effect sizes: the causal effect is underidentified, but whether it’s oxygen or CO2 or nitrogen, it is so large that we should be able to see its repercussions all over in things like the weather (or altitude, yes).
It seems possible (I know of no evidence for or against) that human bodies adapt slowly to differences in O2 and CO2 level. In that case, newcomers to Denver might be smarter or stupider for a while, but after (say) a few months they might be back to baseline, but short-term fluctuations (e.g., sitting for a few hours in an office with slightly depleted O2 and slightly raised O2) could still have detectable cognitive effects.
The magnitude of the variation isn’t nearly the same in the O2 vs CO2 cases. “16% O2 reduction is lost in the noise” is devastating evidence against the theory “0.2% O2 reduction has significant cognitive effects”, but “16% CO2 reduction is lost in the noise” is weaker evidence against the theory “66% and 300% CO2 increases have significant cognitive effects”.
I’m not arguing with you about implausible effect sizes, though. We should especially see significant seasonal effects in every climate where people typically seal up buildings against the cold or the heat for months at a time.
And they also vary CO2 levels systematically by geography as well; if that was enough for a detectable effect on IQ, then the lower CO2 levels around Denver should make the rest of us at lower altitudes, such as sea level, look obviously handicapped. If you believe the altitude point refutes effects of oxygen, then it must refute effects of carbon dioxide and nitrogen as well...
Which is part of my original point about implausible effect sizes: the causal effect is underidentified, but whether it’s oxygen or CO2 or nitrogen, it is so large that we should be able to see its repercussions all over in things like the weather (or altitude, yes).
It seems possible (I know of no evidence for or against) that human bodies adapt slowly to differences in O2 and CO2 level. In that case, newcomers to Denver might be smarter or stupider for a while, but after (say) a few months they might be back to baseline, but short-term fluctuations (e.g., sitting for a few hours in an office with slightly depleted O2 and slightly raised O2) could still have detectable cognitive effects.
The magnitude of the variation isn’t nearly the same in the O2 vs CO2 cases. “16% O2 reduction is lost in the noise” is devastating evidence against the theory “0.2% O2 reduction has significant cognitive effects”, but “16% CO2 reduction is lost in the noise” is weaker evidence against the theory “66% and 300% CO2 increases have significant cognitive effects”.
I’m not arguing with you about implausible effect sizes, though. We should especially see significant seasonal effects in every climate where people typically seal up buildings against the cold or the heat for months at a time.