What atmospheric requirement is suggested by matching ancient Martian water volume to Earth's Arctic Ocean?
Atmospheric pressure substantially greater than current models estimate for that era
When scientists estimate the volume of water necessary to form the vast, recognizable shorelines observed, the inferred water volume can be comparable to Earth's major bodies of water, such as the Arctic Ocean. For water to remain liquid across such a massive surface area, particularly if the planet was otherwise cold, the atmospheric pressure exerted on the surface must have been significantly higher than what is typically calculated in current models for that early era. This discrepancy between the required pressure to sustain the inferred ocean and the pressure predicted by current atmospheric evolution models suggests a major revision might be needed for understanding how quickly and catastrophically Mars lost its early, dense atmosphere.
