About 15 years ago, when everyone first started to notice things
getting warmer, some crazy scientists thought you cold suck the evil
carbon dioxide out of the atmosphere by fertilizing the ocean with
iron. The scientists were eventually shown to not be crazy -- iron
really is in short supply in many open ocean areas and can be the
element limiting phytoplankton growth. But the practical aspects of
fertilizing large amounts of the ocean were thought to be marginal at
best.
Now here's a paper in Science last week that shows pretty clearly it
ain't gonna happen. You'd have to keep dumping iron in the same spot,
over and over, costing a fortune and probably poisoning other aspects
of the oceans. So much for quick fixes.