I’ve been having an interesting discussion with The Hockey Schtick and with Ronan Connolly on the new Gobal Warming Solved site (Archived here). What’s remarkable is the level of agreement. We agree that the atmosphere absorbs and emits radiation (mainly infrared). We agree that one can define an effective emission height in the atmosphere at which the temperature matches the equilibrium non-greenhouse temperature (yes, I realise that the actual emission is more complicated than this – see Eli Rabett’s post, for example). We agree that one can approximate the temperature gradient in the lower atmosphere (troposphere) using the adiabatic lapse rate (yes, I realise that the environmental lapse rate can differ from this – see Science of Doom’s post, for example). One can then estimate the surface temperature by working from the effective emission height (at which the temperature is known) down along the lapse to the surface (i.e., Tsurf = Teq + h dT/dz – using the absolute value of the gradient.)
Where we differ is what we call this process. I call it the greenhouse effect. I believe most others call it the greenhouse effect. The greenhouse gases set the effective emission height in the atmosphere, the lapse rate then sets the surface temperature. Ronan Connolly and The Hockey Schtick appear to call this something else and, consequently, conclude that the greenhouse effect is small, or negligible. An additional consequence of this is that they then conclude that since the greenhouse effect is negligible, adding more greenhouse gases to the atmosphere won’t warm the surface. This is where we differ greatly. Since I maintain that the greenhouse gases are setting the effective emission height in the atmosphere and that adding more will raise this height (which seems obvious, given that having none should mean that it’s on the surface of the planet), adding greenhouse gases should warm the surface.
What seems remarkable is that both The Hockey Schtick and Ronan Connolly seem to be a terminology away from being convinced of the greenhouse effect. They just don’t realise this yet. If they could recognise that the process they describe is actually the greenhouse effect, and if they could recognise the consequences of this realisation, it could be quite an epiphany. Wouldn’t it be great to undergo such an epiphany? The realisation that you now understand something better than you thought you had. Of course, I can’t really bring myself to continue my discussion with them as I’m no longer really sure what we disagree about. We disagree about the name, but it seems that overall we agree about the actual process. So, how does one have a discussion about the existence, or not, of the greenhouse effect when both sides are describing the same process?