The way I think of it is: If you had to terraform a planet, which one would you choose? Option 1: a bombed-out Earth with runaway global warming, acidic ocean

The way I think of it is: If you had to terraform a planet, which one would you choose? Option 1: a bombed-out Earth with runaway global warming, acidic oceans, the end result of mass extinctions where there's dramatically less species diversity and some planet-wide ecologies have utterly collapsed. Option 2: Mars. I would at least hope the answer is obvious. No matter how much we trash Earth, it's still vastly more habitable than Mars or any other planet or moon in this solar system. The human species might not survive what we do to it, but parking a small repository of humans in orbit or on the Moon that would be capable of repopulation is still easily the winning species-survival strategy over terraforming Mars. (Though I suspect it's probably even better to keep that repository someplace on Earth.)