Venus could never have had oceans

Using a climate model, scientists including Jeremy Leconte, CNRS researcher at the Laboratory of Astrophysics of Bordeaux, show that oceans could never have formed on Venus. Their work is published on October 14, 2021 in the journal Nature.

  • 13/10/2021

Venus © NASA / JPL-Caltech Venus © NASA / JPL-Caltech

Whether Venus, one of the Solar System's four terrestrial planets, ever had oceans remains an unsolved puzzle. Although an American study hypothesized that it did, this is now challenged by scientists in a paper published on October 14, 2021 in the journal Nature, involving Jérémy Leconte, CNRS researcher at the Laboratory of Astrophysics of Bordeaux (LAB – CNRS and University of Bordeaux).

Using a state-of-the-art climate model, the research team has come up with an alternative scenario to the American study. Shortly after its birth 4.5 billion years ago, the young Venus was covered with magma. To form oceans, the temperature of its atmosphere would have had to decrease enough for water to condense and fall as rain over a period of several thousand years, as happened on Earth.

However, although the Sun at that time was 30% fainter than it is now, this would not have been sufficient to reduce the young planet's temperature to a point where oceans could form.

Venus, chances of rain: 0%

Such a fall in temperature would only have been possible if the surface of Venus had been shielded from solar radiation by clouds. The researcher's climate model, however, showed that clouds would have preferentially formed on the night side of Venus, where they couldn't shield the surface from sunlight since that side receives none.

On the contrary, instead of acting as a shield, the clouds helped maintain high temperatures by causing a greenhouse effect that trapped heat in the planet's dense atmosphere. According to this climate model, the high surface temperatures prevented any rainfall, and, as a result, the oceans were never able to form.

Data collected by future space missions aiming to study Venus, such as the Envision mission planned for 2030 as well as the Davinci and Veritas missions scheduled for 2029, should make it possible to test these theoretical results.

Artist's impression illustrating the lack of water on Venus © Manchu

*In France, researchers from the  Laboratory of Astrophysics of Bordeaux (LAB - CNRS and University of Bordeaux) and the Laboratoire « atmosphère et observations spatiales » (LATMOS/IPSL – CNRS, University Versailles St Quentin and Sorbonne University) took part in this work. The study was led by the University of Geneva, Switzerland.

Source: CNRS

Bibliographic reference

Day–night cloud asymmetry prevents early oceans on Venus but not on Earth. Martin Turbet, Emeline Bolmont, Guillaume Chaverot, David Ehrenreich, Jérémy Leconte and Emmanuel Marcq.

Scientific contact

Jérémy Leconte
CNRS researcher at the Laboratory of Astrophysics of Bordeaux