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The case for a wet, warm climate on early Mars
J B Pollack1, J F Kasting, S M Richardson
1NASA Ames Research Center, Moffett Field, California 94035, USA.
Icarus
|January 1, 1987
Summary
Early Mars may have had a warm, wet climate due to a dense carbon dioxide (CO2) atmosphere. This required 1-5 bars of CO2, sustained by volcanic activity and carbonate rock decomposition, but eventually dwindled as Mars cooled.
Area of Science:
- Planetary Science
- Climate Modeling
- Geochemistry
Background:
- Early Mars is theorized to have had a dense carbon dioxide (CO2) atmosphere.
- A wet and warm climate is hypothesized for early Mars.
Purpose of the Study:
- To investigate the atmospheric pressure and climate conditions necessary for a warm, wet early Mars.
- To assess the plausibility of a sustained dense CO2 atmosphere through geochemical modeling.
Main Methods:
- Utilized a one-dimensional radiative-convective climate model.
- Developed a geochemical model for the early Martian CO2 cycle, including silicate weathering and volcanic outgassing.
- Estimated weathering and recycling time constants for early Mars.
Main Results:
- 1-5 bars of CO2 pressure were calculated as necessary to maintain temperatures above water's freezing point.
- Silicate weathering and volcanic CO2 resupply (via carbonate decomposition) suggest a CO2 recycling time constant of approximately 10^7 years.
- A total surficial CO2 inventory of 2-10 bars is estimated to be required for sustained warm conditions.
Conclusions:
- A dense CO2 atmosphere, sustained by volcanism, could have enabled a warm, wet early Mars.
- The climate likely cooled as Mars' internal heat engine diminished.
- Spectroscopic detection of carbonates could validate this theory.