Present-day Venus is an inhospitable place with surface temperatures
approaching 750 K and an atmosphere 90 times as thick as Earth's.
Billions of years ago the picture may have been very different. We have
created a suite of 3-D climate simulations using topographic data from
the Magellan mission, solar spectral irradiance estimates for 2.9 and
0.715 Gya, present-day Venus orbital parameters, an ocean volume
consistent with current theory, and an atmospheric composition estimated
for early Venus. Using these parameters we find that such a world could
have had moderate temperatures if Venus had a rotation period slower
than ~16 Earth days, despite an incident solar flux 46 − 70% higher than
Earth receives. At its current rotation period, Venus's climate could
have remained habitable until at least 715 million years ago. These
results demonstrate the role rotation and topography play in
understanding the climatic history of Venus-like exoplanets discovered
in the present epoch.
https://doi.org/10.1002/2016GL069790
https://doi.org/10.1002/2016GL069790
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