Recent climate models suggest that in the past the planet could have had liquid water oceans and a mild climate. It may have been habitable for as long as 3 billion years before succumbing to some sort of climate catastrophe that triggered the runaway greenhouse.

Can Venus be made habitable?

Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere: ... Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere via removal or conversion to some other form.

Can a human survive on Venus?

Most astronomers feel that it would be impossible for life to exist on Venus. Today, Venus is a very hostile place. It is a very dry planet with no evidence of water, its surface temperature is hot enough to melt lead, and its atmosphere is so thick that the air pressure on its surface is over 90 times that on Earth.