[dr_lew]

Why not CO2 permafrost, protected by the soil? I don’t understand how water ice would sublimate so quickly at those temperatures. I guess they would say solar radiation, but in my earth experience, that takes several days, even at earth temperatures.

[dr_lew]

... I mean, it seems like they're saying that this ice lasted millions of years protected by a few centimeters of loose soil, and then disappeared in a few hours when exposed to sunlight.

Hmmm, this is interesting: Therefore, there must be a much larger unidentified CO2 reservoir in the martian subsurface, possibly adsorbed CO2 in the regolith [9,10], to buffer the much larger atmosphere, or it means the total budget of CO2 is present in the atmosphere, and that Mars has today much less CO2 than other telluric planets.

I suppose the Mars people are right, just because they're the experts, but honestly I don't entirely trust them.

[Dead Corpse]

Don’t forget lower pressure as well.