New findings suggest that pouring iron into the ocean could help absorb excess greenhouse gases — unless, that is, it doesn't help at all.

Interpretations of the study, in which researchers measured carbon that fell to the deep ocean after being consumed by plankton, differed widely among media outlets, underscoring the controversial and scientifically tricky nature of iron fertilization.

Some scientists and entrepreneurs say that artificially-added iron can be used to spur blooms of CO2-gobbling plankton — a quick, effective and relatively cheap weapon in the fight against climate change. Other scientists and environmentalists argue that ocean dynamics are too poorly understood to support such radical action, except in small-scale tests designed to provide baseline data.

The battle reached a new level this month, when an Indo-German research team aboard the Polarstern announced their plans to conduct iron fertilization tests in the Scotia Sea, only to be accused of carelessly flouting United Nations laws. The German government temporarily halted the project before approving it on Monday.

In the latest study, published Wednesday in Nature, researchers observed naturally-occurring iron fertilization around the Southern Ocean's Crozet islands, where eroding, iron-rich volcanic rocks fed an Ireland-sized plankton bloom that lasted for two months. Three times more carbon fell to the deep ocean than in a nearby, bloom-free region — a significant difference, but less than expected.

The findings were widely reported, and interpreted in wildly differing ways.

"Legal or not, this kind of 'ocean engineering' may not suck enough carbon out of the atmosphere to reverse climate change," reported the New Scientist.

"Seeding the oceans with iron is a viable way to permanently lock carbon away from the atmosphere and potentially tackle climate change," said the Guardian.

"Proposals to combat global warming by sowing the sea with iron to promote carbon-gobbling plankton may be badly overblown," opined Agence-France Presse.

"Pumping iron into the ocean could help slow climate change," headlined the Telegraph.

At present, it's impossible to know who's right. Only more research will bring a verdict.

In a press release, study co-author Gary Fones, a University of Portsmouth marine geochemist, warned against excessive caution of the sort displayed by the German government in nearly grounding the Polarstern expedition.

“Efforts to find a solution to global warming are under threat by those people who are most concerned about climate change," he said. "But legitimate experiments like this one are crucial to learning more about the effects of iron fertilisation and will help scientists evaluate the merits of such a scheme.”

*Citation: "Southern Ocean deep-water carbon export enhanced by natural iron fertilization." By Raymond T. Pollard, Ian Salter, Richard J. Sanders, Mike I. Lucas, C. Mark Moore, Rachel A. Mills, Peter J. Statham, John T. Allen, Alex R. Baker, Dorothee C. E. Bakker, Matthew A. Charette, Sophie Fielding, Gary R. Fones, Megan French, Anna E. Hickman, Ross J. Holland, J. Alan Hughes, Timothy D. Jickells, Richard S. Lampitt, Paul J. Morris, Florence H. Nedelec, Maria Nielsdottir, Helene Planquette, Ekaterina E. Popova, Alex J. Poulton, Jane F. Read, Sophie Seeyave, Tania Smith, Mark Stinchcombe, Sarah Taylor, Sandy Thomalla, Hugh J. Venables, Robert Williamson and Mike V. Zubkov. Nature, Vol. 457 No. 7229, Jan. 28, 2009

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*Image: Nature

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