We're Already Colonizing Mars
slate.com
slate.com
It would be disappointing if Mars was home to some limited form of life and it all suffered the same bad fate as many Earth species. But everything is a tradeoff.
That being said, I personally don't see Mars colonization (or whatever you want to call it) a realistic solution to humanity's problems.
And then goes on to say that we should be focused on Earth... Can't we do both? Mars colonization is so far down the list of things killing our planet, and seems like a sane response to too-slow societal change.