Those buggers at Space.com are screwing with the URL's

http://www.space.com/scienceastronomy/070125_mars_atmosphere.html

always be deeply suspicious when the URL contains a string of dots! ....

http://www.space.com/scienceastronom...tmosphere.html

This leads us back to the problem of the missing CO2 on Mars. Logic says that it is still present, somewhere. Observation has failed to find it. You can hide a surprising quantity of CO2 in deeply-buried and dispersed carbonate dust. This seems to be part of the story. I tried to push the clathrate/liquid CO2 reservoir side of things and met stiff resistance from the Mars community. (I think, now that EVEN more data has come in on the side of a deep-frozen arid, permafrost-dominated Mars, I might have better success).

The other options are that Mars NEVER had a thick CO2 atmosphere (lost it as fast as it formed?) or that it had one and lost it in a single or a set of catastrophic impacts, like Hellas basin, or jearly strong erosion by the Solar wind (You can't get by with slow, steady erosion, because you need the atmosphere to be gone by around 3.0 to 3.5 Ga)

Personally, I think these guys are still trying to find the "holy grail" - water and life on Mars, and not neccesarily doing science.