For the most part, the resources that we need to survive are renewable if we use them responsibly. And the things that aren’t renewable we can be quite economical about using and should last centuries if not millennia into the future, when hopefully we have better technology to give us alternatives.

We do not need to terraform the Sahara to save Earth. The point is that if you’re so gung-ho about terraforming things, how about you start with a smaller challenge that’s closer to supply lines and labor?

Going to Mars is just a bad plan, period. There’s nothing on Mars for us. Going to the Moon, fine, the low gravity and the Helium-3 and the short distance I can definitely see an argument being made for it. But Mars? There’s no reason whatsoever to go there.