CHAOTIC OBLIQUITY AND THE NATURE OF THE MARTIAN CLIMATE

Recent calculations of the Martian obliquity suggest that it varies ch aotically on timescales longer than about 10(7) years and varies betwe en about 0 and 60-degrees. We examine the seasonal water behavior at o bliquities between 40 and 60-degrees. Up to several tens of centimeter s of water may sublime from the polar caps each year, and possibly mov e to the equator, where it is more stable. CO2 frost and CO2-H2O clath rate hydrate are stable in the polar deposits below a few tens of mete rs depth, so that the polar cap could contain a significant CO2 reserv oir. If CO2 is present, it could be left over from the early history o f Mars; also, it could be released into the atmosphere during periods of high obliquity, causing occasional periods of more-clement climate.