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.
The Mars colony could be useful to test the tools necessary to overcome the hostile climate, and it could make their development (possibly mass development) a higher priority.
So in case the Earth climate starts to change very rapidly, we would have a choice to use already developed and tested equipment, built in existing factories, instead of trying to invent it amidst global chaos.