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Does Ocean Fertilization Sequester Carbon?

Wed Jan 28 2009

Ocean fertilization: dead in the water?

The team observed that some 270 tonnes of iron triggered a two- to threefold increase in biological productivity over an area the size of Ireland. But sediment probes revealed that the export of carbon to the deep ocean was nowhere near as massive as the Kerguelen study, and lab experiments, had suggested.

Although the study design allowed for only a rough estimate of carbon sequestration, the findings are sobering. Previously, scientists had cautioned that removing 30% of the carbon released every year as a result of human activity would require treating an ocean area ten times larger than the entire Southern Ocean, the most fertile waters for iron seeding. Scaled up, the CROZEX results imply that even if the world’s total ocean surface had a craving for iron, satisfying that would not have a large effect on the levels of atmospheric CO2.

This research may confirm the fears that have been previously stated by many, chiefly that the opportunity for iron fertilization varies greatly from location to location, and probably more importantly, that these induced blooms do not actually lead to carbon sequestration. With this information, I’d also like to see if the carbonate cycle or pH are being affected, or what the time to volatilization might be (partial pressure measurements?), at least at lab scale conditions replicating observed phenomena. In any case, this is probably not good news for those hoping fertilization is an easy answer.

The research article is available here and is recommended for people who aren’t afraid to read some less filtered science.

Also, related: Ocean Fertilization Experiment Underway, Under Scrutiny