Venus may have sustained shallow liquid-water oceans and habitable surface temperatures for up to three billion years of its early history, according to computer climate modeling published by researchers at the NASA Goddard Institute for Space Studies (GISS) in New York. The findings, which offer a sharp warning about atmospheric power, suggest that an ocean-bearing Venus could have remained clement for nearly three billion years if liquid water formed early, though no lander has yet drilled an ancient seafloor to confirm the scenario.
NASA Climate Simulations Test Early Venus Habitability
Researchers Michael Way and Anthony Del Genio used NASA’s ROCKE-3D general circulation model to run 45 experiments simulating different stages of Venusian history, according to published studies in JGR: Planets. The team varied surface pressure, topography, soil, rotation, and solar radiation to see whether an ancient ocean could survive as the Sun grew brighter over time. In the optimistic scenario tested by the GISS team, a primordial magma ocean cooled within a few million years, allowing steam to condense into rain and pool into liquid surface water. The simulations incorporated topography from NASA’s Magellan mission and assumed a slow solar day lasting 117 Earth days.
Did you know? Although Venus rotates once relative to the stars in 243 Earth days—and does so backwards compared to most planets—its movement around the Sun means noon to noon takes about 117 Earth days, creating an unusually long dayside heating cycle.
Dayside Cloud Feedback and Slow Rotation
The slow rotation rate of Venus plays a decisive role in the climate models. According to Anthony Del Genio, long heating over the dayside drives warm, wet air upward, where it condenses into a persistent bank of thick clouds near the point facing the Sun. These clouds act like an umbrella, reflecting a substantial fraction of incoming solar energy back into space before it can heat the ground and ocean. This dayside cloud feedback allowed simulated wet worlds to handle more sunlight than a faster-spinning planet could tolerate. Consequently, representative modeled scenarios yielded global mean surface temperatures falling roughly between 20 and 50 degrees Celsius.
Competing Models Challenge the Ancient Ocean Hypothesis
Not all planetary models point to a temperate past. A 2021 Nature study led by Martin Turbet tested a different starting point by simulating a hot steam atmosphere directly following a magma ocean rather than assuming surface liquid water already existed. In Turbet’s simulations, water vapor moved toward the nightside and formed high clouds there, trapping outgoing infrared energy instead of shielding the dayside. Under those conditions, the surface failed to cool enough for steam to condense into rainfall, leaving Venus too hot from the beginning. Furthermore, a 2025 Nature Astronomy analysis of modern volcanic gas estimates suggests the interior is far drier than typical terrestrial volcanic gases, adding weight to the argument that Venus may have lost its water before it could enter the mantle.
Future Missions Aim to Settle the Debate
Definitive proof of an ancient Venusian ocean remains out of reach until spacecraft can directly sample the planet’s chemistry and geology.
Frequently Asked Questions
Did NASA prove that Venus definitely had an ocean?
No. The research relies on climate simulations to test whether an ocean-bearing Venus could remain clement if liquid water formed early. It does not establish that an ocean actually existed.
What caused Venus to become so hot today?
Researchers suggest that massive volcanic outpourings could have released carbon dioxide faster than surface weathering could remove it, thickening the atmosphere, accelerating evaporation, and driving a runaway greenhouse effect.
How long could early Venus have remained habitable?
The GISS modeling indicates that representative clement scenarios could remain stable for nearly three billion years, with habitable surface conditions lasting up to two billion years of its early history.
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