Originally Posted by Xephyr
The amount of gas there is. Venus has much more gas than Earth.
You might be able to ballpark it. The problem is the uncertainty. A 20 degree C uncertainty (for example - real uncertainty may be different) is plenty good enough to distinguish Earth climate from Venus climate (which is more than 400 deg. C hotter at the surface), but it's not enough to gauge impact on humans, since 20 degrees makes a huge
bloody difference to our lives. So gas volume considerations are enough to tell us we'll never look like Venus. They aren't enough to tell us what we really want to know.