Mars feels like a really important backup plan

If there’s even a small chance that Earth is fucked from global warming, we need to be able to go to Mars. I heard a cool concept that we can basically artificially create global warming on Mars by putting greenhouse gases in the atmosphere.

Unless it’s life or death, I personally wouldn’t move to a planet with less than a million people on it (imagine Austin is the entire world, that feels like the bare minimum for me).

How much money and time would it take to get a million people to Mars?