Terra's Big Neighbor

[iancampbell]

Yes, of course there would be a strong greenhouse effect at sea level. As a more severe version of this, it is thought that the conditions at an altitude of about 40km in Venus's atmosphere are relatively benign. (As far as temperature and pressure are concerned, anyway.)

That is an excellent point. Venus does have Earthlike conditions (pressure, temperature) at higher altitude. I wonder how you'd move them to ground level. You'd end up with the problems of the big solar-thermal mass of the ground and ocean right under your feet but...

If you can get those Earth-like conditions someplace on Venus, then you can probably get it elsewhere.

Yup. I was postulating a rather less severe Venus-type hothouse (maybe 450K and 10 bar at sea level, and much more water) with a suitably high upland area or several, leaving livable conditions at ground level but in a limited number of places of relatively small area.

Actually, I stole the idea from Niven; his world of Plateau with Mount Lookitthat is pretty much like this. Except for the height of the plateau; he sets it at 40km high, which is probably impossible. (The crush strength of rocks isn't high enough.)