I definitely agree in principle, but on the other hand, it's really hard to imagine an event that would render Earth less hospitable than Mars. In general, these catastrophes would just make Earth more like Mars.
Nuclear war? Mars is a desolate wasteland that's bombarded with ionizing radiation from space (because it lacks both a sufficient atmosphere and a magnetic field to protect it).
Asteroid impact? Unless it eliminates all of our atmospheric oxygen, ozone, hydrogen and nitrogen and drops the average surface temperature to -55°C, we're still better off here.
Pandemic? If we can protect a colony from the environment of Mars, we should be able to keep at least that many people safe from a pandemic. (Just stick your Mars-bubble in Antarctica if nothing else. It's a lot like Mars except it has better temperatures, an atmosphere that you can breathe if you need to and the water is more readily available.)
Nuclear war? Mars is a desolate wasteland that's bombarded with ionizing radiation from space (because it lacks both a sufficient atmosphere and a magnetic field to protect it).
Asteroid impact? Unless it eliminates all of our atmospheric oxygen, ozone, hydrogen and nitrogen and drops the average surface temperature to -55°C, we're still better off here.
Pandemic? If we can protect a colony from the environment of Mars, we should be able to keep at least that many people safe from a pandemic. (Just stick your Mars-bubble in Antarctica if nothing else. It's a lot like Mars except it has better temperatures, an atmosphere that you can breathe if you need to and the water is more readily available.)