for the "White Mars" hypothesis -- at least none with regard to the famous (albeit imaginary) Hoffman Flows of CO2.

His conceptual breakthrough was not those flows, however. Instead, he demonstrated the likelihood that the surface of Mars has mostly always been cold, usually colder than it is today. That fundamental realization is changing most workers' understanding of Martian history, which in turn is affecting notions of Martian biology. If Mars has always been cold, and there was no early "clement" era, the question is: could Mars have developed native biology, and how could there be Martian biology today?

Despite the "Cold Mars" model, however, there are signs all over the planet of massive volcanism and volcanic resurfacing, some of it very recent. Now you can't have that kind of volcanic activity on the surface without a hot interior. Despite the lack of indisputable evidence that Mars is currently volcanically active, signs of recent volcanism are too strong to dismiss.

So. We may find that a cold surface has been affected -- throughout the planet's history -- by an active interior (which may have provided periodic "clement" conditions in some regions some of the time, and that would have very interesting implications for biology.)

But there were no CO2 flows. Ever.

Cheers, BRFelix