Max™ wrote:Without an atmosphere to transport energy around the planet the night side would be very cold, and gases don't radiate as effectively as they convect.
You seem to be missing my point, though,that convection doesn't change the ultimate energy balance at all. Instead of what I've been saying, let me try to put it in the same terms as you. Once a everything is in equilibrium, we should have Pin = Pout, representing the total rate at which energy enters and leaves the planet-atmosphere system. The only way for energy to get in from space, or back out to it, is radiation.
Let's take Rt to represent all the power given off as radiation from anywhere on the planet or its atmosphere. So if all of it escapes directly into space, we should have Rt = Pout = Pin. But if we add greenhouse gases, some portion of the radiation being given off by the planet is not going to escape, and so now Pout / Rt < 1. Then we get Rt > Pin.
If we assume albedo isn't changed we would still have the same value for Pin, agreed? So adding greenhouse gases has meant that Rt has had to increase; the planet-atmosphere system is giving off more radiation than it did in the case without them. If we expect the radiation emitted is mainly thermal, that means the temperature in at least some part of the system must have gone up.
Note: of course this is an ideal case since any gas absorbing radiation is likely to change the albedo a bit. But this is where the different spectra come in: carbon dioxide doesn't interact with light from the star nearly so much as it does with infrared from the planet, so will change Pout / Rt much more than Pin, and you'll still get the same kind of result.
This is the idea of global warming in its most basic form. With all the extra things that have been brought up, I've found it somewhat hard to tell if you have any objections with this concept itself, or simply the details of how climate scientists calculate the values, or something else.