Ah Alex, may your stomach roast in Hell ! :-) I rather liked Baghdad Bob, but hope that I don't go down in history in the same boat as he!

I'm sure the final answer for Mars will involve some water and some CO2. In a sense, my "victory" will be in moving the Mars establishment away from a 100% water model for everything on Mars. For now, I continue to argue the 100% CO2 model, partly as a devil's advocate, partly to see IF it is possible (my null hypothesis), and partly because it arouses such strong reactions in certain people.

The next paper is well under way, and should address many of the issues about thermal gradients. We actually have a surprising bank of data on this for Mars, although it is hidden as other sorts of information, like the relationship between magnetic anomalies and impacts, which yields a Curie-point depth, or the flexural rigidity of the crust, which yields a softening isotherm. These all point to much lower heat flow than the conventional model.

The flexural rigidity also answers the heat-flow history, since the age of a load can be (roughly) estimated from crater ages. Sure, if you go back far enough, you can shallow subsurface liquid water under a frozen cryosphere, but you STILL stabilise liquid CO2 at shallower depths than liquid water at any past time or in any geothermal anomaly.