I think the average pressure should stay about the same because the mass stays the same, but if it compresses maybe the pressure goes up in low-lying areas and goes down at higher altitudes.
According to Wikipedia, CO2 can liquify at around 5 atmospheres, though it has to be pretty cold at that pressure. The phase diagram shows it as a liquid around room temperature (300K or so) at about a hundred atmospheres. Which makes a liquid ocean of CO2 is at least sort of plausible if the temperature drops far enough.
No, and the other comments about gas laws and volume are overthinking it a bit. Pressure at the surface is caused by the weight of the atmosphere. On earth, a column of air extending from sea level to space, with cross sectional area one square inch, weighs 15 pounds.
Neither the temperature or volume of the atmosphere changes its weight. (Ok, I suppose a hotter atmosphere has more volume and extends higher into space and weighs slightly less, as it is farther from the planet on average, but I assume that’s a fairly negligible effect)
You forget things like condensation/solidification of things like CO2 in lower temperatures, so atmosphere composition would change dramatically, and so would overall 'weight' of the column to space you mention.
Anyway as other mention it doesn't change that much in survability, having 116 days long single Venus-day would mean temperature differences would be extreme, probably in hundreds of degrees.
You beat me to it. Just posted a comment saying the same thing. I think if we solidified the CO2 we would have an easier time dealing with it, but IDK. Then again, we might be able to get to work now by just suspending some blimps in the upper atmosphere. They could use solar energy to sequester the CO2 and start lowering the pressure & temperature.
I read an SF story a few years ago where the idea was to sequester the carbon of Venus into blocks of diamond. A minor bit of (ahem) atmosphere in a pretty good novel . . . just don't remember the title.
While the equation you give is valid, I think it is probably not that useful given the "volume" is open to space and so we can't solve this equation.
I think more useful is a static equilibrium, specifically that d(pressure)/d(altitude)=-density(pressure,temperature)*gravity(altitude).
Which gives you roughly an exponential falloff with altitude if you assume gravity is constant (which is fine if it's a small fraction of planet radius) and molecular weight and temperature are constant (that's definitely not true but oh well)
EDIT: for the question asker: reducing the temperature would have a first order effect of just making the density gradient steeper, but surface pressure would be the same. The second order effect might be that the surface absorbs some CO2, which would actually reduce surface pressure.
It's not, though, the Venus atmosphere does not behave like an ideal gas all around, it transitions into a supercritical dense liquid towards the ground.
According to Wikipedia, CO2 can liquify at around 5 atmospheres, though it has to be pretty cold at that pressure. The phase diagram shows it as a liquid around room temperature (300K or so) at about a hundred atmospheres. Which makes a liquid ocean of CO2 is at least sort of plausible if the temperature drops far enough.
https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Car...