This is the fundamental Paradox of Mars.

Mars today is dry and cold. Every possible form of measurement agrees on this from chemical analysis of Mars rocks to spectroscopy of its surface and atmosphere.

The Paradox of Mars: In the past, the sun was fainter and Mars should have been colder, yet features indicative of water flow can be seen on the planet. How can it possibly have been warmer in the past?

The conventional answer to the paradox is to propose an exotic cocktail of greenhouse gases that allow the early Martian atmosphere to have been warm and wet. This explains the Distributary Valley Networks. The later outburst "floods" are explained by very peculiar models of subsurface water recycling on a cold planet, although some workers continue the warm wet atmosphere to later times, despite the evidence of very low erosion rates post Noachian times. These "explanations" lead to further paradoxes of why the Earth did not overheat, and how the water recyling occurred.

The White Mars solution to the Paradoxis that Mars was never warm and wet, except transiently in the Noachian due to major impacts. This explains the Noachian Distributary Valley Networks. The later "floods" are explained as density flows emerging from collapsed terrain where CO2-rich ices degas and supply vapour support to the flow, like in Terrestrial volcanic pyroclastic flows. There are no further paradoxes.

      Created: May 2002
      Last modified: May 2002
      Authorised by:  Head, Earth Sciences

      Maintained by: Nick Hoffman
      Email: nhoffman@unimelb.edu.au