Circumpolar Ocean Stability On Mars 3 Billion Years Ago

By Keith Cowing
Status Report
October 3, 2023
Filed under , , , , , , ,
Circumpolar Ocean Stability On Mars 3 Billion Years Ago
3D GCM output at 40◦ obliquity and H2=10% for the rain precipitation, snow and ice fraction at the surface, snowfall, sea/ground surface temperature. Black contour lines represent surface elevation level (-2000, 0, 2000 and 8000 meters) and the red contour line is the paleo-shoreline (-3900 meters). — astro-ph.EP

What was the nature of the Late Hesperian climate? Warm and wet or cold and dry? Formulated this way the question leads to an apparent paradox since both options seem implausible. A warm and wet climate would have produced extensive fluvial erosion but few valley networks have been observed at the age of the late Hesperian.

A too cold climate would have kept any northern ocean frozen most of the time. A moderate cold climate would have transferred the water from the ocean to the land in the form of snow and ice. But this would prevent tsunami formation, for which there is some evidence. Here, we provide new insights from numerical climate simulations in agreement with surface geological features to demonstrate that the Martian climate could have been both cold and wet.

Using an advanced General Circulation Model (GCM), we demonstrate that an ocean can be stable, even if the Martian mean surface temperature is lower than 0∘C. Rainfall is moderate near the shorelines and in the ocean. The southern plateau is mostly covered by ice with a mean temperature below 0∘C and a glacier return flow back to the ocean.

This climate is achieved with a 1 bar CO2 dominated atmosphere with 10\% H2. Under this scenario 3 Ga, the geologic evidence of a shoreline and tsunami deposits along the ocean/land dichotomy are compatible with ice sheets and glacial valleys in the southern highlands.

Schmidt F., Way M. J., Costard F., Bouley S., Séjourné A., Aleinov I

Comments: 7 pages, 3 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (
Cite as: arXiv:2310.00461 [astro-ph.EP] (or arXiv:2310.00461v1 [astro-ph.EP] for this version)
Focus to learn more
Journal reference: Proceedings of the National Academy of Sciences, 2022, 119, e2112930118
Related DOI:
Focus to learn more
Submission history
From: Frédéric Schmidt
[v1] Sat, 30 Sep 2023 18:44:13 UTC (2,396 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻