A couple of years ago, I read the mars series from kim stanley robinson. Now NASA held a debate on martian terraforming.
Should we do it? Well, that gets down to a question that we've never had to face on Earth before: the distinction between nature and life. On Earth there is no meaningful distinction between nature and life, even in the remotest, coldest deserts. We see that distinction for the first time when we look beyond the Earth, when we look at the moon. There's nature; there's no life. When we look at Mars, we also see nature, probably no life. It's different from the moon, and we lack the word that distinguishes between something that's dead, and something that was never alive. The moon was never alive. Mars is dead. The question in my mind is - should we bring it back to life?
2007-06-25: This seems a bit optimistic
I believe it's a 50% chance that young children now alive will walk on martian meadows...will swim in martian lakes
2015-06-06: terrible music but nice martian terraforming viz

https://www.youtube.com/watch?t=262&v=WjNssEVlB6M

2018-02-22: Adding a magnetic shield
In a talk at the NASA Planetary Science Vision 2050 Workshop at the agency’s headquarters, Green presented simulations, models, and early thinking about how a Martian magnetic field might be re-constituted and the how the climate on Mars could then become more friendly for human exploration and perhaps communities. It consisted of creating a “magnetic shield” to protect the planet from those high-energy solar particles. The shield structure would consist of a large dipole—a closed electric circuit powerful enough to generate an artificial magnetic field. Simulations showed that a shield of this sort would leave Mars in the relatively protected magnetotail of the magnetic field created by the object. A potential result: an end to large scale stripping of the Martian atmosphere by the solar wind, and a significant change in climate. “The solar system is ours, let’s take it. And that, of course, includes Mars. But for humans to be able to explore Mars, together with us doing science, we need a better environment.”