The population of Greenland is: 56309
The population of Namibia is: 1820916

I've been to Namibia. Swakopmund is a pleasant little town on the Atlantic coast and Windhoek is a respectable city (fascinating iron-nickel meteor display in the town center).

Like most people on this website, I've flown over Greenland travelling to nicer places. Greenland is almost all ice except for the coasts. I suspect it is easier to live in Gusev Crater than central Greenland.

The Greenland versus Mars argument has a weakness in that Greenland's inhabitants have the option of going somewhere else. This is where the whole concept of "economics" gets very slippery. Case in point: Most of Northern Queensland, Australia is uninhabited. There are places in Queensland that should be major cities, e.g. Normanton. Normanton should be a major sea port because of its strategic location on the Gulf of Carpentaria and being next to a significant river. Normanton was once a moderate sized city when the copper mines were still going strong but depopulated after the copper ran out (it's still a nice place to visit). The Queensland and/or Australian government blundered when they built the rail lines from Mt. Isa (the mines there are rich with galena) to Townsville rather than to Normanton. Townsville's population base was secure due to sugar cane plantations. A rail line from central Queensland to Normanton would have kept Normanton alive and thus better served Australia's strategic and economic interests. It might also have kept the towns of Croydon and Georgetown fully populated since they depended on Normanton. It only takes a little bit of economic incentive to encourage people to stay put. However if that incentive goes away then people will simply leave to places where life is easier.

Anyway, once a colony has been estabilished on Mars with an initial group of 1000 people, they're staying put (they won't have the option of return). They will not be like the former inhabitants of Normanton who could simply get on their horses or in their carriages and ride south to Brisbane. The situation on Mars will be very similar to Newfoundland and Jamestown in the 17th century. Jamestown almost died in its early history. The people there were mostly poor Englishman with little wilderness experience. The indians were fairly ferocious and made life difficult. After things got grim, the folks living in Jamestown probably wanted to return to England but didn't have the option. You might counter argue that 17th century Virginia is much more inhabitable than 21st century Mars. However the technology available to a 21st century American is vasty better than the technology of a 17th century Englishman. Again the economics is slippery.

Gary