In a catastrophic events on the same scale as the asteroid impact that wiped out the dinosaurs, mankind's best chance of survival may lie in off-world colonies. Many scientists think Mars would be viable option, due to its similarity to Earth. What would it take to make it habitable? Futurism website made an infographic, explaining the steps: Please Register or Log in to view the hidden image! Source: http://futurism.com/wp-content/uploads/2016/04/Terraforming-Mars_v6.jpg
Never really had much faith in any terraforming process, but who knows what technological advances will enable us to do: If we can theoretically achieve such a goal in a 1000 years, great! I'm all for it!
Kim Stanley Robinson's excellent Mars trilogy explores terraforming in great detail. While he undoubtedly takes some liberties with the facts for the purposes of the story there is a lot of sound science in the work and a good exploration of the ethics of terraforming. I thoroughly recommend it. Red Mars, Green Mars, Blue Mars.
