It could be all accumulated at the poles as ice. That’s at least one plausible theory. Most freshwater on earth is on the poles too. On Mars it would be hidden under millennial of dust, so really hard to say as long no rover checks there or we do it in person. From afar it’s really hard to tell
margenreich t1_iu3z8a6 wrote
Reply to comment by mojojojo31 in A recently released set of topography maps provides new evidence for an ancient northern ocean on Mars. The maps offer the strongest case yet that the planet once experienced sea-level rise consistent with an extended warm and wet climate, not the harsh, frozen landscape that exists today. by Wagamaga
It could be all accumulated at the poles as ice. That’s at least one plausible theory. Most freshwater on earth is on the poles too. On Mars it would be hidden under millennial of dust, so really hard to say as long no rover checks there or we do it in person. From afar it’s really hard to tell