Elon Musk, the billionaire founder and CEO of the private spaceflight company SpaceX, wants to help establish a Mars colony of up to 80,000 people by ferrying explorers to the Red Planet for perhaps $500,000 a trip.
(...) we've put all our eggs in one basket. If we were on many worlds and were to mess up down here, there's a way for the human species to continue. I don't for a moment propose that the Earth is a disposable planet, and we have to put enormous efforts into making sure we don't muss up down here. But there is a chance.
This does not follow. One possible (although very unlikely) result of climate change is a much more severe situation resulting in a Venus like situation (although not as high as temp and not as much nasty stuff in the atmosphere). If that happens, Mars will be much easier to survive on than Earth, since with a lot of energy from nuclear power, extremely cold environments are much more hospitable than extremely hot environments. Current models makes such a strong runaway result unlikely, but it is a possibility.