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A model for the evolution of CO2 on Mars
R M Haberle1, D Tyler, C P McKay
1Space Sciences Division, NASA/Ames Research Center, Moffett Field, California 94035, USA. haberle@humbabe.arc.nasa.gov
Icarus
|May 1, 1994
Summary
Mars
Area of Science:
- Planetary Science
- Climate Modeling
- Atmospheric Science
Background:
- Understanding Mars's past climate is crucial for astrobiology.
- Previous models have struggled to reconcile early Mars with present conditions.
Purpose of the Study:
- To model the evolution of carbon dioxide (CO2) on Mars.
- To determine conditions necessary for a warm, wet early Mars.
Main Methods:
- Constructed a CO2 evolution model incorporating weathering, regolith uptake, polar cap formation, and atmospheric escape.
- Calculated surface temperatures using a modified energy balance model accounting for solar luminosity and greenhouse effects.
Main Results:
- No model scenario supports a warm, wet early Mars evolving to present conditions without external factors.
- Relaxing the early Mars constraint suggests initial CO2 inventories of 0.5-1.0 bar.
- Polar cap formation significantly impacts climate evolution, acting as a critical control on surface pressure.
Conclusions:
- A warm, wet early Mars requires either a brighter early sun, additional greenhouse gases, or lower polar albedo.
- The critical initial amount of CO2 for climate stability is estimated between 1 and 2 bar.
- Polar cap dynamics play a pivotal role in Mars's climate history.