That's a super-optimistic view of colonization and terraforming of Mars, from a book that is generally super-optimistic about the future of humankind in space (its subitle is "Colonizing the Galaxy in Eight Easy Steps"). Published in 1992 and 1994 (1994 paperback has an introduction by Arthur C. Clarke), I bought a copy a few months ago and have kept it nearby for occasional browsing. Savage's scope and vision are truly amazing, even if many of the things he proposes would not be exactly "easy" and some of them probably not even necessary. Even if many details are not realistic (some may not even be physically possible), this is not science fiction either - he did extensive research into many technologies to flesh out the plans with details that at least aspire to practicality - with some examples succeeding more than others.-Marshall T. Savage, The Millennial Project, page 246
His early plan includes building floating colonies in tropical waters and using OTEC's (ocean thermal energy converter) to extract energy from the temperature differential between deep water and surface water. He proposes that such colonies could become self-sufficient and eventually even generate surplus energy and food (from mariculture) for export. The foundation that sponsors the development of these ocean-based colonies would use the profits and the knowledge gained to move on to colonies in space, on the Moon, and on Mars, and eventually beyond the solar system. Would people join such a project as residents of ocean-based colonies, space colonies, etc.? I don't know - there are social and political implications here too of course. Savage certainly has a utopian agenda.
I haven't read the whole book yet, in part because I am both impressed and skeptical. I'm probably most impressed by the fact that he has taken the long view and developed and documented such a boldly optimistic plan, whether it's practical or not. So I guess I need to suspend my disbelief on such things as his "Bifrost" (Earth-based mass driver) space launch system and just read the whole book for its scope and optimism.