Iron fertilization. This is the name given to the process where iron filings are intentionally sprayed (or added) to the ocean.Why? The idea is that the iron, stimulates the growth of plankton, that in term removes CO2 from the atmosphere.
The good news? It actually works. Plankton does absorb CO2. When it dies, it sinks to the bottom of the ocean, taking the carbon with it.
The bad news? The amount of carbon involved is tiny. Too tiny. More CO2 would be released collecting the iron and sending out to sea than would be absorbed by the plankton.
So, back to the drawing board!
To read more on this go to the page: http://en.wikipedia.org/wiki/Iron_fertilization