We may not ship the entire population off to the red planet, but as our environment gets more and more dangerous, the technologies we develop to live on the Martian surface will help us here, too.
When Earth's sky turns red and the clouds become flaking black soot, when the air chokes human animals like a gulp of vaporized chlorine and the plants are pulled from their roots by the wind—people will wonder where we can go. They will consider a better time or a better place, and they will do what humans do. They will look for any way to survive. But will they actually go to the equally uninhabitable dunes of Mars?