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Yet Another Reason Ocean Iron Fertilization Isn't Such a Great Idea

Diatoms may end up hogging too much of the iron dumped into the ocean for the procedure to have much long-term effect.
Photo: Wikipedia

Ocean iron fertilization has been touted as a way to geoengineer our way out of the climate problem. But the more it's researched, the more dumping tons of iron into the ocean in the hopes of creating a carbon-sucking algal bloom seems like a risky bet. A new study adds to the pile, finding that iron fertilization efforts could be thwarted by some of ocean's smallest organisms.

New analysis by the Department of Energy's Argonne National Laboratory suggests that diatoms may end up hogging too much of the iron dumped into the ocean for the procedure to have much long-term effect. Diatoms apparently have a propensity to take in more iron than they need for photosynthesis, storing the rest in their skeleton and shell, thereby reducing the amount of iron available for other plankton.

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The research, published in Nature Communications, used x-rays to fill in gaps in our knowledge of how much iron gets trapped in the sinking skeletons of diatoms and is taken out of the food chain.

In the short term this isn't a big deal, but over time, the analysis speculates, the growth in diatoms could starve out other plankton, spurring on the growth of microbes that don't need as much iron, thereby reducing the amount of algal blooms that can absorb carbon dioxide—exactly contrary to the whole point of ocean iron fertilization.

While not necessarily the final word on the viability of ocean iron fertilization, it does raise an important question about a procedure that has some very vocal proponents, not afraid to try to prove the technique's worth using some dodgy methods.

Last October, entrepreneur Russ George (the former CEO of Planktos, a for-profit company trying to commercialize ocean iron fertilization) conducted what has been described as a rogue science experiment in the waters off British Columbia.

George dumped 100 tons of iron dust into the waters just south of the Alaskan Gulf. He managed to produce a 3,861 square mile plankton bloom—as he hoped to. Controversially, George got the approval of a local indigenous council for the experiment, though they said afterwards they thought he was conducting a "salmon enhancement project" not an experiment in geoengineering.

How risky is ocean iron fertilization? Back in 2009, the Royal Society made a comprehensive assessment of different climate modification techniques. They found that while it is not as risky as some other techniques, such as pumping sulfate particles into the atmosphere to reflect the incoming solar radiation, ocean iron fertilization has a "high potential for unintended and undesirable ecological side effects" and has not been proven effective.