A key argument for making Mars habitable seems to be as a hedge for humanity in case we destroy mother earth. Is anyone in the space sciences looking seriously at how the human race could survive subterranean?
A lot of the technology that can be used to colonize Mars or the Moon can also be used on Earth to live subterranean. We cannot expect to live on the surface of the Moon or Mars without having to worry about the radiation from the Sun. Therefore, a number of engineers are looking at ways to turn Lunar and Martian caves into dwelling places for humans - either as explorers or permanent colonists. There are programs in place to develop sub-Lunar and sub-Martian settlements, which would be useful here on Earth in the event that the surface was no longer habitable.