The general idea has been known for a long time:
Berner, Lasaga, and Garrels
"The carbonate-silicate geochemical cycle and its effect on
atmospheric carbon dioxide over the past 100 million years" http://shadow.eas.gatech.edu/~jean/paleo/Berner_1983.pdf
I haven't looked into it super-closely, but it seems to me that Schuiling
et al. might be underestimating the cost. Still, though, even if the cost
is 2x higher than estimated, it's still cheap compared to the end of the
world.
In particular, they make the point that CO2 capture does *not* need to be
done right at the smokestack. One CO2 molecule looks a lot like another,
and the atmosphere is well mixed. So CO2 molecules are fungible. You
can capture them wherever it's most convenient. Also you don't need
to take it out overnight. A time scale of a few years is just fine,
especially compared to the alternative, which is hundreds of years.
If this is anywhere close to right, it solves important political problems
as well as operational problems. Climate deniers rely on saying either
there's no problem, or there's nothing we can do about it (or both). It
changes the discussion completely is there is something that can be done
at a not-completely-crazy cost.
So we make a rule that says if you want to put X amount of fossil
carbon into the air, you have to find enough olivine or wollastonite
or whatever to compensate for at least /twice/ that much, grind it
to dust and disperse it somewhere. If this has beneficial side-effects
(fertilizer) so much the better.
I worry that the deleterious side-effects have not been fully
accounted for. Olivine can turn into things like chrysotile,
which is another name for asbestos, which you might not want
to be dispersing in enormous quantities.
If it works out, this is a nice free-enterprise free-market solution.
Note that "free enterprise" does not mean I am free to dump my sewage
into your yard. The same goes for CO2. Right now the cost of dumping
CO2 is an externality; we need to make the polluters internalize this
cost.
This would add a noticeable (but not catastrophic) amount to the cost
of burning fossil carbon. This makes people unhappy, but still it's
better than the end of the world. It has a nifty free-market side
effect, namely making renewables more attractive.