Here’s a recent webinar on terraforming Mars from the NASA MAVEN Mission to Mars youtube channel. The TL;DR is that it will be monumentally difficult, but sooner or later we are likely to try it. In the meantime, we shouldn’t get hung up on the feasibility of the endeavour as we make plans for exploring and colonizing Mars.
Along the way is a great deal of information on the history of Mars, including the questionable relevancy of its lack of magnetic field, and details on what it would take to terraform a planet.
Humans love the idea of a rebel. But only the idea. Take action too far outside the box of current experience and you begin to hear the Greek Chorus of naysayers heckling you, gleefully glomming onto anything that might pull you back within accepted norms.
Such has been the case recently regarding a paper in the journal Nature Astronomy, which reported that there does not appear to be enough CO2 on Mars to allow for terraforming. I can’t count the number of articles that have floated through my various feeds starting with the mocking phrase “Sorry Elon…” Google it yourself and see what I mean.