There are several other proposed solutions. Cutting carbon and taxing it was near the bottom of the list as prioritized by this group of researchers:
http://fixtheclimate.com/component-1/the-result-prioritization/
So why have they sorted the options so that the most unrealistic ones are all at the top?
I can't see any other reason than that these people want to make sure that absolutely nothing is done. Even if they were just incompetent, we would expect the options to end up in a more or less
random order.
I mean, let's look at the top of their list:
1. Research into marine cloud whitening.
First we note that this calls for research into a hitherto completely unproven technology, where we don't know either if it could work, or what unintended consequences it would have. Then, it's pretty obvious that even if it would work, it would be politically impossible to carry this out on the scale that would clearly be necessary.
2. Technology-led policy response
The completely
amazing idea of improving technology and using whatever (unspecified) technology we might discover. That's just
brilliant! I wish I was clever enough to think of that. Awesome stuff.
3. Research into stratospheric aerosol insertion
See 1.
4. Research into carbon storage.
See 1 again, but at least this option has the advantage that if we were to discover that it was doable, it
might actually be politically viable (except, of course, we can't know that as we don't know how it would be done, if it could be done).
5. Planning for adaptation.
As if this was not already being done. Hint: it's one of the major focuses of the Copenhagen discussions.