Whole planet coupling between climate, mantle, and core: Implications for the evolution of rocky planets

TL;DR

This paper explores how interactions between climate, mantle, and core influence the evolution of rocky planets, affecting their habitability and magnetic field generation, with implications for understanding Earth and Venus.

Contribution

It highlights the importance of planetary coupling processes in determining long-term planetary evolution and habitability, emphasizing the need for further research to constrain these interactions.

Findings

Cooler climates promote plate tectonics and core cooling.

Plate tectonics sustains long-term climate stability and magnetic fields.

Venus's hot climate results from lack of plate tectonics and core cooling.

Abstract

Earth's climate, mantle, and core interact over geologic timescales. Climate influences whether plate tectonics can take place on a planet, with cool climates being favorable for plate tectonics because they enhance stresses in the lithosphere, suppress plate boundary annealing, and promote hydration and weakening of the lithosphere. Plate tectonics plays a vital role in the long-term carbon cycle, which helps to maintain a temperate climate. Plate tectonics provides long-term cooling of the core, which is vital for generating a magnetic field, and the magnetic field is capable of shielding atmospheric volatiles from the solar wind. Coupling between climate, mantle, and core can potentially explain the divergent evolution of Earth and Venus. As Venus lies too close to the sun for liquid water to exist, there is no long-term carbon cycle and thus an extremely hot climate. Therefore plate tectonics cannot operate and a long-lived core dynamo cannot be sustained due to insufficient core cooling. On planets within the habitable zone where liquid water is possible, a wide range of evolutionary scenarios can take place depending on initial atmospheric composition, bulk volatile content, or the timing of when plate tectonics initiates, among other factors. Many of these evolutionary trajectories would render the planet uninhabitable. However, there is still significant uncertainty over the nature of the coupling between climate, mantle, and core. Future work is needed to constrain potential evolutionary scenarios and the likelihood of an Earth-like evolution.