Terraforming is a nice long term thing but I would think some underground habitats could be built in the short term. If there's some water ice, oxygen, and use

Terraforming is a nice long term thing but I would think some underground habitats could be built in the short term. If there's some water ice, oxygen, and useful minerals such as iron that can be harvested, a colony could be almost self-sustaining once they've set up their solar power, smelters, digging equipment and fabricating tools. Probably about a thousand people would be the tipping point. I'm imagining a turn-key colony that initially accommodates 1,000 people and can expand arbitrarily, that is robotically prepared, then the humans arrive to a heated, lighted, oxygenated, self-sufficient habitat. Once this has been standardized, it's a matter of dropping these in various spots around the planet, not too far apart, humanity can then colonize the planet in 1,000 person increments. It's not a solution for our climate problems back on Earth, obviously, but it's a way to ensure some redundancy, should the Earth become uninhabitable through climate catastrophe or war. Or an asteroid strike.