I read a Short Sharp Shock many years ago and thought it extremely original and very inventive, the first of the Mars Trilogies seemed too much like a story of partner conquest for me (not unlike the Stingray relationship of Troy and Marina), so I passed it over after the first half of the book.
The eventual move by humans to inhabit Mars I would guess is not going to happen before the end of this century, making the 'prediction' some 80 years out, but of course the need of everyone to feel they have to 'own' their part of the land is synonymous with every part of mans history on this planet, so it could all work out pretty much as Robinson writes. Doom and gloom books are ten a penny at our local emporium and so the trilogy offering does dull compared to the gems once a selction have been taken home for perusal.
Almost all the chemicals used in getting the rockets off the lauchpad and into space are not 'natural', they can almost certainly be made using something other than fossil fuels.
As for colonisation, it used to be a question of exploration for the sake of it, because it was 'there'. Now the monetry aspects of the next step of mankind makes that exploration insignificant compared to the risk.
No planet near us can be colonised safely, a virus outbreak, act of vandalism, or the simplest fracture of the needed amosphere makes the need to look at a nearer solution vital.
Once a group of poeple have spent a few years at the bottom of the ocean, or perched on Everest we will have some probability of success on another planet. Its not going to happen just because some astronauts spent a few days walking on the moon, and can live for a year on a space station..
agreed, rocket lox/hydrogen are renewables, but hydrazine?
i was thinking more in terms of metal ores, once "rich" ones exhausted, metals become harder to extract. Also petrochemicals (plastics) etc, but lots of stuff can be synthesised from plants, and solar energy is plentiful.
i still can't see any incentive, not at present, can you?.