I'd think even a dinosaur-killer-stricken earth with all kinds of climate and other problems would still be a lot more pleasant to live on than Mars. I mean, if

I'd think even a dinosaur-killer-stricken earth with all kinds of climate and other problems would still be a lot more pleasant to live on than Mars. I mean, if you imagine an Earth that's been totally ruined in every imaginable way you're basically describing Mars, but still better because at least there's 1G of gravity and a really good built-in radiation shield.