I know we won't settle Mars this century; it will be a permanent scientific outpost, not a colony and will be a ghost town planet generations after we pour billions and even trillions into it. 

We will settle and terraform Antarctica and Greenland as the ice melts, and it will melt rapidly into the 22nd century. We will build dikes to try to save New York City, and I see that eventually we would add on to and replace the sea coast we lose, and fill in the backwaters with freshwater lakes behind the new sea coast