re: Geo-engineering option
I'm leery of any of the "macroengineering" ideas for solving climate problems. The "dump iron into the ocean" idea falls into this category.
Reducing emissions (build nukes) is like turning down a rheotstat slowly. We don't know enough about the machine to whack it with a monkey wrench.
There are also liability issues. Whoever did something like this would be blamed for every damn storm for the next fifty years.