It's casually assumed sometimes that if we destroy earth through climate change or some other human made catastrophe, we might be able to move to Mars. Of course we'd need to make Mars habitable first, but assuming that we can, it's one option to surviving if we totally ruin our home planet.
In this Ted Talk stellar astronomer Lucianne Walkowicz, who works on NASA's Kepler mission which searches for places in the cosmos that might support life, explains why that is such a bad idea.
"We're at a tipping point in human history, a species poised between gaining the stars and losing the planet we call home." she begins.
Walkowicz worries that in talking about colonizing Mars we'll forget about earth, instead concentrating and focusing our attentions on how to get to Mars in the hope that exploring that will save us. When, actually, we should be looking at how to save earth before we even consider fleeing to another planet.
Firstly she says that "compared to Earth Mars is a pretty terrible place to live" but also she says that the more the Kepler mission looks for planets like earth, the more you come to appreciate the wonder and uniqueness of our own planet.
"It is hubris to believe that interplanetary colonization alone will save us from ourselves, but planetary preservation and interplanetary exploration can work together." she notes. "If we truly believe in our ability to bend the hostile environments of Mars for human habitation, then we should be able to surmount the far easier task of preserving the habitability of the Earth."
To compliment Walkowicz's Ted Talk, the video below from Wired explains why the human body itself, even if technology is, isn't ready for the Mars environment just yet.