[gregallan]

If you're saying that moles/m^3 of CO2 might be constant while pmm of CO2 is increasing, that implies that atmospheric pressure at sea level is dropping. And it isn't.

[nonbel]

I'm not saying it is constant. Where do you see that?

Also, who says the pressure isn't dropping? Can that even be measured to detect such a small difference?

And the volume and/or temperature of the troposphere could change instead.

Finally, what about water vapor compensating?

[rabidrat]

The temperature is increasing, though...

[yongjik]

"Atmospheric pressure" is basically "total mass of air on top of us, per surface area". So it doesn't (directly) depend on temperature.

Edit: Sorry, should be "total weight of air". My physics is rusty.

[nonbel]

If you took the same mass of air and put it in two tropospheres, one is 2 km high and the other 20 km high. Would there be the same surface pressure?

[yongjik]

You cannot put air at 2 km and then at 20 km high! Of course the second layer will just flow down until it's supported by the first layer, which is in turn supported by the ground. So your question doesn't really make physical sense.

[nonbel]

I agree, everything is much more complicated than your original comment implied.

[yongjik]

I... I just explained why everything adds up to what my original comment said... (sigh)