The difference between e-mail and regular mail is that computers handle e-mail, and computers never decide to come to work one day and shoot all the other computers.
To be clear, geoengineering won't solve global warming. It's not a 'techno-fix.' It would be enormously risky and almost certainly lead to troubling unforeseen consequences.
Blended-reality technology could play in a limited, walled-garden world, but history suggests that it won't really take off until it offers broad freedom of use.
Neodymium is one of 17 'rare-earth metals,' and these elements have turned out to be critical to the rapidly-growing green technology industries.