These schemes are all insane. Just imagine the damage done to the environment by:

1) Tens of millions of fans floating in the ocean and blowing air on the ice.

2) Oceans being flooded with massive amounts of green algea, sucking up CO2 and producing who knows what out of it.

3) Filling the skys with sulfer aerosols to block out the sun.

There is no way CO2 can be worse than any of those.