Climate Cycling on Early Mars Caused by the Carbonate-Silicate Cycle

Abstract

For decades, scientists have tried to explain the evidence for fluvial activity on early Mars, but a consensus has yet to emerge regarding the mechanism for producing it. One hypothesis suggests early Mars was warmed by a thick greenhouse atmosphere. Another suggests that early Mars was generally cold but was warmed occasionally by impacts or by episodes of enhanced volcanism. These latter hypotheses struggle to produce the amounts of rainfall needed to form the martian valleys, but are consistent with inferred low rates of weathering compared to Earth. Here, we provide a geophysical mechanism that could have induced cycles of glaciation and deglaciation on early Mars. Our model produces dramatic climate cycles with extended periods of glaciation punctuated by warm periods lasting up to 10 Myr, much longer than those generated in other episodic warming models. The cycles occur because stellar insolation was low, and because CO2 outgassing is not able to keep pace with CO2 consumption by silicate weathering followed by deposition of carbonates. While CO2 by itself is not able to deglaciate early Mars in our model, we assume that the greenhouse effect is enhanced by substantial amounts of H2 outgassed from Mars' reduced crust and mantle. Our hypothesis can be tested by future Mars exploration that better establishes the time scale for valley formation.

14 pages, 2 figures, EPSL accepted

References in corpus (4)

• Global modelling of the early Martian climate under a denser CO2 atmosphere: Water cycle and ice evolution
• Warming early Mars with CO2 and H2
• Outgassing History and Escape of the Martian Atmosphere and Water Inventory
• Testing the Early Mars H2-CO2 Greenhouse Hypothesis with a 1-D Photochemical Model

Cited by in corpus (8)

• A warmer and wetter solution for early Mars and the challenges with transient warming
• Thermodynamic and Energetic Limits on Continental Silicate Weathering Strongly Impact the Climate and Habitability of Wet, Rocky Worlds
• Habitability of Earth-like stagnant lid planets: Climate evolution and recovery from snowball states
• Warming Early Mars with Climate Cycling: The Effect of CO2-H2 Collision-induced Absorption
• Subsistence of ice-covered lakes during the Hesperian at Gale crater, Mars
• An Energy Balance Model for Rapidly and Synchronously Rotating Terrestrial Planets
• The influence of surface $C{O}_2$ condensation on the evolution of warm and cold rocky planets orbiting Sun-like stars
• The Drake Equation as a Function of Spectral Type and Time