MARS may once have been scoured by dry-ice glaciers. This suggestion
comes from a member of the team of scientists which proposed that the youthful
Mars was kept warm enough for water by clouds of dry ice—frozen carbon dioxide
(This Week, 22 November 1997, p 6).
Raymond Pierrehumbert of the University of Chicago says dry ice crystals in
the Martian atmosphere would inevitably fall as CO2 snow at the
poles—just as water snow falls at the Earth’s poles. On Earth, water is
returned to the atmosphere when glaciers flow back to warmer climes and
melt.
On Mars, dry-ice glaciers would replenish the dry-ice clouds, says
Pierrehumbert. “We are going to have to invent the field of Martian dry-ice
glaciology,” he says.
