To be fair, you dont actually have to terraform a planet to colonize it, theres nothing physics defying with having a civilization of people living in airtight buildings with controlled climate inside indefinitely. It still isnt a solution to climate change for any number of obvious reasons, but I dont know that anyone that seriously wants to see a mars colony start in their lifetime actually intends to terraform the place first. Terraforming gets thrown around casually in science fiction, but to actually reshape the entire surface and climate of a planet that way, even if we had the requisite technology and infrastructure right now, would be a process that would probably take millennia at best and be incredibly destructive to any infrastructure existing on the surface during that time. If you want to build a mars colony now, rather than at some point where we’re ancient history after human civilization has finished what would be to them the largest and longest construction project ever, then you pretty much have to accept Mars’s climate conditions for what they are and build around them rather than try to change them.