On the Possible Evolutionary History of the Water Ocean on Venus

TL;DR

This study explores Venus's potential past water ocean evolution using a 1D climate model, suggesting it may have been habitable for up to 4.6 billion years under certain conditions, informing planetary habitability research.

Contribution

It introduces a 1D radiative-convective model analysis of Venus's water history, considering parameters like albedo and humidity, and discusses implications for habitability and exoplanet studies.

Findings

Venus could have hosted a water ocean for up to 1 billion years under specific conditions.

3D calculations suggest the ocean might have persisted over 4.6 billion years.

Runaway greenhouse effects require additional factors beyond solar luminosity increase.

Abstract

We have investigated the possible evolutional history of the water ocean on Venus, adopting the one dimensional radiative-convective model,including the parameters as albedo and relative humidity. Under this model, it has the possibility that the habitable zone could include Venus. It could continue for $\sim 1$ Gy in faint young solar flux increasing, with modest parameters such as albedo = 0.3, relative humidity (RH=1), and $p_{n0}=10^5 $Pa. If we relax parameters considering the 3-Dimensional calculations, the ocean could exist there longer than $\sim$ 4.6 Gy. In such cases, we have to consider the cause of runaway other than just solar luminosity increasing. It is important to investigate Venus history for the coming future of Earth and observations of exoplanets for their historical habitable zones.