Just one point
Hi Guys
I'm with Nick, reluctantly. I've hung out for a Wet Mars for a long time, but a cold White Mars is looking more realistic. Only uncertainty is whether there was a "faint young Sun" as some solar wind models imply a higher primordial mass for the Sun over the first Gyr or so. This would've kept the isolation within ~ 10% of the present day. But Mars is cold now, and would still be cold then. We just can't assume it was colder.
Adam