NCPA - National Center for Policy Analysis

Seeding Oceans With Iron Could Reduce Atmospheric CO2

November 14, 2000

Seeding the oceans with iron could potentially trap several hundred million tons of the greenhouse gas carbon dioxide (CO2) from the air each year, scientists report in Nature. Moreover, the world's fisheries could expand if the process is commercially exploited, as some firms hope to do.

  • In an experiment conducted last year between Tasmania and Antarctica, researchers released three and a half tons of dissolved iron over about 30 square miles of sea.
  • The addition of iron, an essential element lacking in vast, barren stretches of the Pacific and Antarctic oceans, caused an estimated 10-fold rise in the amount of phytoplankton -- one celled plants that live near the surface.
  • The patch eventually covered 660 square miles, pulling perhaps several thousand tons of carbon dioxide from the air.

The response far exceeded predictions and persisted for more than six weeks. Previous blooms created in the tropics dissipated in half that time.

The phytoplankton could sink to the ocean bottom, reducing atmospheric CO2, a heat-trapping gas implicated in global warming. The cold ocean water sinks to great depths, where it can remain for centuries.

Using computer models incorporating the results from the experiment, Andrew J. Watson, a geochemist at the University of East Anglia in Norwich, England, found the effect was consistent with changes in past geological periods when iron dust blown from the continents enriched the southern seas, causing plankton blooms that appear to have reduced atmospheric CO2 levels.

Several companies are planning to fertilize the sea with iron, both to attack global warming and to stimulate fisheries. And the United States Department of Energy is considering partially underwriting a proposal from the University of Hawaii and Greensea Ventures to conduct a larger test of the iron-fertilizing process west of the Galápagos Islands.

Source: Andrew C. Revkin, "Antarctic Test Raises Hope on Earth Warming; Iron-Fed Plankton Absorbs Greenhouse Gases," New York Times, October 12, 2000.


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