Top Facts on Ocean Awesomeness
It is unclear why the diatoms incorporate iron in their shells. Ingall suggested it could be because the element is freely available, which makes the diatoms hog it in order to place other types of plankton at a disadvantage.
"Just like someone walking through a buffet line who takes the last two pieces of cake, even though they know they'll only eat one, they're hogging the food," said Ingall in a statement.
That would mean little iron is available for other types of plankton more efficient at capturing carbon dioxide from the atmosphere. The ecology of the ocean would shift, from a plankton bloom that is better at removing carbon to a bloom dominated by diatoms that are best at removing iron.
These are theories that need further testing, and the lack of knowledge is exactly why George's solo iron fertilization experiment in an important salmon feeding ground earned him a swift rebuke from environmentalists.
Other better monitored experiments have come out with unclear results about the benefits of fertilization. The experiments usually happen in the Southern Ocean, which is one of the largest sinks in the world for anthropogenic carbon dioxide. Every year in the fall, sea ice starts forming around the continent of Antarctica. The water immediately below the layer of ice becomes salty and dense, and it sinks even as waters from the ocean depths, high in nutrients and carbon dioxide, rise to the surface. And when the sea ice melts in the spring, plankton thrive in the nutrient-rich waters and the ocean becomes green-hued.